U.S. patent application number 13/155098 was filed with the patent office on 2011-09-29 for rendezvousing resource requests with corresponding resources.
This patent application is currently assigned to Microsoft Corporation. Invention is credited to Richard L. Hasha, Gopala Krishna R. Kakivaya, Thomas Lee Rodeheffer.
Application Number | 20110238841 13/155098 |
Document ID | / |
Family ID | 35517374 |
Filed Date | 2011-09-29 |
United States Patent
Application |
20110238841 |
Kind Code |
A1 |
Kakivaya; Gopala Krishna R. ;
et al. |
September 29, 2011 |
RENDEZVOUSING RESOURCE REQUESTS WITH CORRESPONDING RESOURCES
Abstract
The present invention extends to methods, systems, and computer
program products for rendezvousing resource requests with
corresponding resources. Doubly linked sorted lists are traversed
using modulo arithmetic in both directions. Sorted lists can be
partitioned based on a multiple proximity metrics. Node routing
tables provide a logarithmic index to nodes within the ID space of
the federation infrastructure to facilitate more efficient routing.
Messages can be routed to nodes within a ring and proximally routed
to nodes in other partitioned rings.
Inventors: |
Kakivaya; Gopala Krishna R.;
(Sammamish, WA) ; Hasha; Richard L.; (Seattle,
WA) ; Rodeheffer; Thomas Lee; (Mountain View,
CA) |
Assignee: |
Microsoft Corporation
Redmond
WA
|
Family ID: |
35517374 |
Appl. No.: |
13/155098 |
Filed: |
June 7, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11220756 |
Sep 7, 2005 |
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13155098 |
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10971451 |
Oct 22, 2004 |
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11220756 |
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Current U.S.
Class: |
709/226 |
Current CPC
Class: |
H04L 45/54 20130101;
H04L 45/02 20130101; H04L 45/04 20130101 |
Class at
Publication: |
709/226 |
International
Class: |
G06F 15/173 20060101
G06F015/173 |
Claims
1. In a federation infrastructure, a method for creating and
maintaining a node distribution data structure that references each
of a plurality of nodes in the federation infrastructure, the
method comprising: an act of a computer system, which includes at
least one processor, accessing a federation infrastructure
comprising plurality of nodes organized into a root ring and a
plurality of sub-rings below the root ring that each group the
plurality of nodes based on proximity criterion, each node
including: a corresponding numeric identifier uniquely selected
from a range of numeric values and that determines a sorted order
of the plurality of nodes in each of the rings; and a corresponding
routing table that represents separate routing information for the
root ring of nodes and for each of the plurality of sub-rings for
which said node is a member, the separate routing information
referencing a plurality of routing nodes within each ring for which
said node is a member and of which said node has knowledge; an act
of accessing a first routing table from a first node to identify a
first plurality of routing nodes of which the first node has
knowledge, the first node being a member of a plurality of the
sub-rings and storing the separate routing information for the root
ring and each of the plurality of the sub-rings; an act of
subsequently accessing each routing table from each of the
plurality of nodes in the federation infrastructure by recursively
accessing at least a second routing table from at least one of the
routing nodes for which the first node has knowledge; and based on
the accessed each routing table from each of the plurality of
nodes, an act of forming a node distribution data structure that
references each of the plurality of nodes in the federation
infrastructure.
2. The method as recited in claim 1, wherein the plurality of
routing nodes within each ring for which said node is a member are
members of the same proximal ring.
3. The method as recited in claim 1, wherein the node distribution
data structure is used to address a message to at least one other
node in the federation infrastructure.
4. The method as recited in claim 1, wherein the node distribution
data structure is used to determine at least one node from a set of
nodes to address a message to.
5. The method as recited in claim 2, further comprising sending a
plurality of messages instead of a single message.
6. The method as recited in claim 1, wherein each of the plurality
of sub-rings represent different proximal rings that sort the
plurality of nodes based on different proximity criteria.
7. The method as recited in claim 6, wherein the node distribution
data structure is used by the first node to address a message to at
least one other node in the federation infrastructure that is a
member of a different proximal ring.
8. The method as recited in claim 1, wherein the node distribution
data structure comprises a connectivity graph.
9. The method as recited in claim 1, further comprising: an act of
receiving at the first node an indication that a message is to be
sent to from the first node to each of the plurality of nodes of
the federation infrastructure; and an act of sending the message to
each of the plurality of nodes using the node distribution data
structure.
10. The method as recited in claim 1, wherein the corresponding
routing table includes, for each ring for which said node is a
member: a predecessor node identified by a predecessor numeric
identifier sorted immediately prior to said corresponding numeric
identifier within said ring; a successor node identified by a
successor numeric identifier sorted immediately subsequent to said
corresponding numeric identifier within said ring; a plurality of
neighbor nodes identified by a first sequence of numeric
identifiers sorted immediately prior to said corresponding numeric
identifier within said ring and a second sequence of numeric
identifiers sorted immediately subsequent to said corresponding
identifier within said ring; and an index of other nodes, each
having a logarithmically-increasing distance from said node within
said ring.
11. In a federation infrastructure, a system configured to create
and maintain a node distribution data structure that references
each of a plurality of nodes in the federation infrastructure, the
system comprising: at least one processor; and one or more computer
storage media having stored thereon computer executable
instructions that, when executed by the at least one processor,
implement a method comprising: an act of accessing a federation
infrastructure comprising plurality of nodes organized into a root
ring and a plurality of sub-rings below the root ring that each
group the plurality of nodes based on proximity criterion, each
node including: a corresponding numeric identifier uniquely
selected from a range of numeric values and that determines a
sorted order of the plurality of nodes in each of the rings; and a
corresponding routing table that represents separate routing
information for the root ring of nodes and for each of the
plurality of sub-rings for which said node is a member, the
separate routing information referencing a plurality of routing
nodes within each ring for which said node is a member and of which
said node has knowledge; an act of accessing a first routing table
from a first node to identify a first plurality of routing nodes of
which the first node has knowledge, the first node being a member
of a plurality of the sub-rings and storing the separate routing
information for the root ring and each of the plurality of the
sub-rings; an act of subsequently accessing each routing table from
each of the plurality of nodes in the federation infrastructure by
recursively accessing at least a second routing table from at least
one of the routing nodes for which the first node has knowledge;
and based on the accessed each routing table from each of the
plurality of nodes, an act of forming a node distribution data
structure that references each of the plurality of nodes in the
federation infrastructure.
12. The system as recited in claim 11, wherein the plurality of
routing nodes within each ring for which said node is a member are
members of the same proximal ring.
13. The system as recited in claim 11, wherein the node
distribution data structure is used to address a message to at
least one other node in the federation infrastructure.
14. The system as recited in claim 11, wherein the node
distribution data structure is used to determine at least one node
from a set of nodes to address a message to.
15. The system as recited in claim 13, further comprising sending a
plurality of messages instead of a single message.
16. The system as recited in claim 10, wherein each of the
plurality of sub-rings represent different proximal rings that sort
the plurality of nodes based on different proximity criteria.
17. The system as recited in claim 16, wherein the node
distribution data structure is used by the first node to address a
message to at least one other node in the federation infrastructure
that is a member of a different proximal ring.
18. The system as recited in claim 10, wherein the node
distribution data structure comprises a connectivity graph.
19. The system as recited in claim 11, further comprising: an act
of receiving at the first node an indication that a message is to
be sent to from the first node to each of the plurality of nodes of
the federation infrastructure; and an act of sending the message to
each of the plurality of nodes using the node distribution data
structure.
20. One or more computer storage devices having stored thereon
computer executable instructions that, when executed by at least
one processor of a computer system, implement a method for creating
and maintaining a node distribution data structure that references
each of a plurality of nodes in the federation infrastructure, the
method comprising: an act of the computer system accessing a
federation infrastructure comprising plurality of nodes organized
into a root ring and a plurality of sub-rings below the root ring
that each group the plurality of nodes based on proximity
criterion, each node including: a corresponding numeric identifier
uniquely selected from a range of numeric values and that
determines a sorted order of the plurality of nodes in each of the
rings; and a corresponding routing table that represents separate
routing information for the root ring of nodes and for each of the
plurality of sub-rings for which said node is a member, the
separate routing information referencing a plurality of routing
nodes within each ring for which said node is a member and of which
said node has knowledge; an act of accessing a first routing table
from a first node to identify a first plurality of routing nodes of
which the first node has knowledge, the first node being a member
of a plurality of the sub-rings and storing the separate routing
information for the root ring and each of the plurality of the
sub-rings; an act of subsequently accessing each routing table from
each of the plurality of nodes in the federation infrastructure by
recursively accessing at least a second routing table from at least
one of the of routing nodes for which the first node has knowledge;
and based on the accessed each routing table from each of the
plurality of nodes, an act of forming a node distribution data
structure that references each of the plurality of nodes in the
federation infrastructure.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/220,756, filed Sep. 7, 2005, and entitled
"Rendezvousing Resource Requests With Corresponding Resources,"
which is a continuation of U.S. patent application Ser. No.
10/971,451, filed Oct. 22, 2004, and entitled "Rendezvousing
Resource Requests With Corresponding Resources." The contents of
each of the foregoing applications are herein incorporated by
reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. The Field of the Invention
[0003] The present invention relates to accessing resources and,
more particularly, to rendezvousing resource requests with
corresponding resources.
[0004] 2. Background and Relevant Art
[0005] Computer systems and related technology affect many aspects
of society. Indeed, the computer system's ability to process
information has transformed the way we live and work. Computer
systems now commonly perform a host of tasks (e.g., word
processing, scheduling, and database management) that prior to the
advent of the computer system were performed manually. More
recently, computer systems have been coupled to one another and to
other electronic devices to form both wired and wireless computer
networks over which the computer systems and other electronic
devices can transfer electronic data. As a result, many tasks
performed at a computer system (e.g., voice communication,
accessing electronic mail, controlling home electronics, Web
browsing, and printing documents) include electronic communication
between a number of computer systems and/or other electronic
devices via wired and/or wireless computer networks.
[0006] However, to utilize a network resource to perform a
computerized task, a computer system must have some way to identify
and access the network resource. Accordingly, resources are
typically assigned unique identifiers, for example, network
addresses, that uniquely identify resources and can be used to
distinguish one resource from other resources. Thus, a computer
system that desires to utilize a resource can connect to the
resource using the network address that corresponds to the
resource. However, accessing a network resource can be difficult if
a computer system has no prior knowledge of a network address for a
network resource. For example, a computer system can not print a
document at a network printer unless the computer system (or
another networked computer system) knows the network address of the
network printer.
[0007] Accordingly, various mechanisms (e.g., Domain Name System
("DNS"), Active Directory ("AD"), Distributed File Systems ("DFS"))
have been developed for computer systems to identify (and access)
previous unknown resources. However, due to the quantity and
diversity of resources (e.g., devices and services) that are
accessible via different computer networks, developers are often
required to develop applications that implement a variety of
different resource identification and access mechanisms. Each
different mechanism may have different coding requirements and may
not provide a developer with all the functionality that is needed
in an application.
[0008] For example, although DNS has a distributed administration
architecture (i.e., centralized management is not required), DNS is
not sufficiently dynamic, not self-organizing, supports a weak data
and query model, and has a fixed set of roots. On the other hand,
AD is sufficiently dynamic but requires centralized administration.
Further, aspects of different mechanisms may not be compatible with
one another. For example, a resource identified using DNS may not
be compatible with DFS routing protocols. Thus, a developer may be
forced to choose the most suitable mechanism and forgo the
advantages of other mechanisms.
[0009] Mechanisms for identifying resources can be particularly
problematic in peer-to-peer networks. DNS provides a lookup
service, with host names as keys and IP addresses as values, that
relies on a set of special root servers to implement lookup
requests. Further, DNS requires management of information (NS
records) for allowing clients to navigate the name server
hierarchy. Thus, a resource must be entered into DNS before the
resource can be identified on a network. On larger scale networks
where nodes frequently connect and disconnect form the network
relying on entry of information is not always practical.
Additionally, DNS is specialized to the task of find hosts or
services and is not generally applicable to other types of
resources.
[0010] Accordingly, other mechanisms for resource identification
and access have been developed to attempt to address these
shortcomings. A number of mechanisms include distributed lookup
protocols that are more scalable than DNS. These mechanisms use
various node arrangements and routing algorithms to route requests
to corresponding resources and to store information for lookup.
[0011] At least one of these mechanisms utilizes local multi-level
neighbor maps at each node in a network to route messages to a
destination node. This essentially results in an architecture where
each node is a "root node" of a corresponding tree of nodes (the
nodes in its neighbor map). Messages are incrementally routed to a
destination ID digit by digit (e.g., ***6=>**46=>,
*346=>2346, where *s represent wildcards). The routing
efficiency of these types of mechanisms is O(log N) routing hops
and require nodes to maintain a routing table of O(log N) size.
[0012] At least one other of these mechanisms assigns nodes a
unique ID that is taken from a linear ring of numbers. Nodes
maintain routing tables that contain pointers to their immediate
successor node (according to ID value) and to those nodes whose ID
values are the closest successor of the value ID+2.sup.L. The
routing efficiency of these types of mechanisms is also O(log N)
routing hops and require nodes to maintain a routing table of O(log
N) size.
[0013] At least one further mechanisms requires O(log N.sup.1/d)
routing hops and requires nodes to maintain a routing table of O(D)
size. Thus, the routing efficiency of all of these mechanisms
depends, at least in part, on the number of nodes in the
system.
[0014] Further, since IDs (for at least some of the mechanisms) can
be uniformly distributed around a ring, there is always some
possibility that routing between nodes on the ring will result in
some inefficiency. For example, routing hops can cross vast
geographic distances, cross more expensive links, or pass through
insecure domains, etc. Additionally, when message routing involves
multiple hops, there is some chance that such events will occur
multiple times. Unfortunately, these mechanisms do not take into
account the proximity of nodes (physical or otherwise) with respect
one another. For example, depending on node distribution on a ring,
routing a message from New York to Boston could involve routing the
message from New York, to London, to Atlanta, to Tokyo, and then to
Boston.
[0015] Accordingly, at least one other more recent mechanism takes
proximity into account by defining proximity as a single scalar
proximity metric (e.g., IP routing hops or geographic distance).
These mechanisms use the notion of proximity-based choice of
routing table entries. Since there are many "correct" node
candidates for each routing table entry, these mechanisms attempt
to select a proximally close node from among the candidate nodes.
For these mechanisms can provide a function that allows each node
to determine the "distance" of a node with a given IP address to
itself. Messages are routed between nodes in closer proximity to
make progress towards a destination before routing to a node that
is further away. Thus, some resources can be conserved and routing
is more efficient.
[0016] Unfortunately, these existing mechanisms typically do not
provide for, among other things, symmetric relationships between
nodes (i.e., if a first node considers a second node to be its
partner, the second node considers the first node as a partner as
well), routing messages in both directions (clockwise and
counterclockwise) on a ring, partitioning linked lists of nodes
based on a plurality of proximity metrics, and routing messages
based on a plurality of proximity metrics proximity. Therefore
systems, methods, computer program products that utilize these
mechanisms to rendezvous resource requests with a corresponding
resource would be advantageous.
BRIEF SUMMARY OF THE INVENTION
[0017] The foregoing problems with the prior state of the art are
overcome by the principles of the present invention, which are
directed towards methods, systems, and computer program products
for rendezvousing resource requests with corresponding resources.
In some embodiments, the nodes of a federation infrastructure are
partitioned. A sorted linked list containing node IDs that have
been assigned to nodes in the federation infrastructure is
accessed. Proximity categories that represent a plurality of
different proximity criterion for partitioning the sorted link list
are accessed. The sorted linked list is partitioned into one or
more first sub lists based on a first proximity criterion, each of
the one or more first sub lists containing at least a subset of the
node IDs from the sorted linked list. A first sub list, selected
from among the one or more first sub lists, is partitioned in to
one or more second sub lists based on a second proximity criterion,
each of the one or more second sub lists containing at least a
subset of node IDs contained in the first sub list.
[0018] In other embodiments, for example as depicted in FIG. 3, a
node routing table is populated. An immediate predecessor node is
inserted into the routing table. An immediate successor node is
inserted into the routing table. Appropriate neighborhood node
identifiers are inserted into the routing table, the neighborhood
nodes identified from the sorted linked list in both the first
direction and in a second opposite direction based on a
predetermined or estimated neighborhood range and neighborhood
size. Appropriate routing nodes identifiers are inserted into the
routing table, the routing nodes identified from the sorted linked
list in both the first and second directions based on the number
base and field size of the ID space for the federation
infrastructure, the routing nodes representing a logarithmic index
of the sorted link list in both the first and second
directions.
[0019] In yet other embodiments, a node routing table can be
populated taking proximity criteria in to account. A predecessor
node for each hierarchically partitioned routing ring the current
node participates in is inserted into a routing table, each
hierarchically partitioned routing ring being partitioned in
accordance with corresponding proximity criteria and containing at
least subsets of the bi-directional linked list of a parent ring. A
successor node for each hierarchically partitioned routing ring the
current node participates is inserted into the routing table.
Appropriate neighborhood nodes for each hierarchically partitioned
routing ring the current node participates in are inserted into the
routing table. Appropriate routing nodes for each hierarchically
partitioned routing ring the current node participates in are
inserted into the routing table.
[0020] In further other embodiments, a message is routed,
potentially based on one or more proximity criteria defining a
corresponding one or more classes of nodes, towards a destination
node. A receiving node receives a message along with a destination
number indicating a destination node and optionally one or more
proximity criteria. The receiving node, potentially among nodes in
a current class of nodes, determines it is at least one of
numerically further from the destination number than a
corresponding predecessor node and numerically further from the
destination number than a corresponding successor node. It is
determined that the destination is not in a neighborhood set of
nodes, potentially among nodes in the current class of nodes,
corresponding to the receiving node.
[0021] An intermediate node from a routing table corresponding to
the receiving node is identified, the intermediate node being
numerically closer to the destination number than other routing
nodes in the corresponding routing table. The message is sent to
the intermediate node. The intermediate node can continue routing
the message. The message eventually reaches the destination node
when a node that receives the message is numerically closer to the
destination number than either its successor or predecessor nodes.
In embodiments that route based on one or more proximity criteria,
this numerical closeness may be with respect to nodes in a selected
class of nodes.
[0022] Thus, routing a message based on proximity criteria includes
routing to a destination node (ID) by progressively moving closer
to the destination node within a given proximal ring (class of
nodes) until no further progress can be made by routing within that
ring. Determining that no further progress can be made occurs when
the destination number lies between the current node's ID and its
successor or predecessor nodes' IDs. At this point, the current
node starts routing via its partner nodes in the next larger
proximal ring in which it participates. This process of
progressively moving towards the destination node by climbing along
the partitioning path towards the root ring terminates when the
destination node is reached.
[0023] These and other objects and features of the present
invention will become more fully apparent from the following
description and appended claims, or may be learned by the practice
of the invention as set forth hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] To further clarify the above and other advantages and
features of the present invention, a more particular description of
the invention will be rendered by reference to specific embodiments
thereof which are illustrated in the appended drawings. It is
appreciated that these drawings depict only typical embodiments of
the invention and are therefore not to be considered limiting of
its scope. The invention will be described and explained with
additional specificity and detail through the use of the
accompanying drawings in which:
[0025] FIG. 1 illustrates an example of a federation
infrastructure.
[0026] FIG. 2 illustrates an example of a computer architecture
that facilitates routing request indirectly to partners.
[0027] FIG. 3 illustrates an example binary relationship between
nodes in a federation infrastructure in the form of a sorted list
and corresponding ring.
[0028] FIG. 4 illustrates an example ring of rings that facilitates
proximal routing.
[0029] FIG. 5 illustrates an example proximity induced partition
tree of rings that facilitates proximal routing.
[0030] FIG. 6 illustrates a suitable operating environment for the
principles of the present invention.
[0031] FIG. 7 illustrates an example flow chart of a method for
populating a node routing table that takes proximity criteria into
account
[0032] FIG. 8 illustrates an example flow chart of a method for
partitioning the nodes of a federation infrastructure.
[0033] FIG. 9 illustrates an example flow chart of a method for
populating a node routing table.
[0034] FIG. 10 illustrates an example flow chart of a method for
numerically routing a message towards a destination node.
[0035] FIG. 11 illustrates an example flow chart of a method for
proximally routing a message towards a destination node.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] The foregoing problems with the prior state of the art are
overcome by the principles of the present invention, which are
directed towards methods, systems, and computer program products
for rendezvousing resource requests with corresponding resources.
In some embodiments, the nodes of a federation infrastructure are
partitioned. A sorted linked list containing node IDs that have
been assigned to nodes in the federation infrastructure is
accessed. Proximity categories that represent a plurality of
different proximity criterion for partitioning the sorted link list
are accessed. The sorted linked list is partitioned into one or
more first sub lists based on a first proximity criterion, each of
the one or more first sub lists containing at least a subset of the
node IDs from the sorted linked list. A first sub list, selected
from among the one or more first sub lists, is partitioned in to
one or more second sub lists based on a second proximity criterion,
each of the one or more second sub lists containing at least a
subset of node IDs contained in the first sub list.
[0037] In other embodiments, for example as depicted in FIG. 3, a
node routing table is populated. An immediate predecessor node is
inserted into the routing table. An immediate successor node is
inserted into the routing table. Appropriate neighborhood node
identifiers are inserted into the routing table, the neighborhood
nodes identified from the sorted linked list in both the first
direction and in a second opposite direction based on a
predetermined or estimated neighborhood range and neighborhood
size. Appropriate routing nodes identifiers are inserted into the
routing table, the routing nodes identified from the sorted linked
list in both the first and second directions based on the number
base and field size of the ID space for the federation
infrastructure, the routing nodes representing a logarithmic index
of the sorted link list in both the first and second
directions.
[0038] In yet other embodiments, a node routing table can be
populated taking proximity criteria in to account. A predecessor
node for each hierarchically partitioned routing ring the current
node participates in is inserted into a routing table, each
hierarchically partitioned routing ring being partitioned in
accordance with corresponding proximity criteria and containing at
least subsets of the bi-directional linked list of a parent ring. A
successor node for each hierarchically partitioned routing ring the
current node participates is inserted into the routing table.
Appropriate neighborhood nodes for each hierarchically partitioned
routing ring the current node participates in are inserted into the
routing table. Appropriate routing nodes for each hierarchically
partitioned routing ring the current node participates in are
inserted into the routing table.
[0039] In further other embodiments, a message is routed,
potentially based on one or more proximity criteria defining a
corresponding one or more classes of nodes, towards a destination
node. A receiving node receives a message along with a destination
number indicating a destination node and optionally one or more
proximity criteria. The receiving node, potentially among nodes in
a current class of nodes, determines it is numerically further from
the destination number than a corresponding predecessor node and
numerically further from the destination number than a
corresponding successor node. It is determined that the destination
is not in a neighborhood set of nodes, potentially among nodes in
the current class of nodes, corresponding to the receiving
node.
[0040] An intermediate node from a routing table corresponding to
the receiving node is identified, the intermediate node being
numerically closer to the destination number than other routing
nodes in the corresponding routing table. The message is sent to
the intermediate node. The intermediate node can continue routing
the message. The message eventually reaches the destination node
when a node that receives the message is numerically closer to the
destination number than either its successor or predecessor nodes.
In embodiments that route based on one or more proximity criteria
this numerical closeness may be with respect to nodes in a selected
class of nodes.
[0041] Thus, routing a message based on proximity criteria includes
routing to a destination node (ID) by progressively moving closer
to the destination node within a given proximal ring (class of
nodes) until no further progress can be made by routing within that
ring. Determining that no further progress can be made occurs when
the destination number lies between the current node's ID and its
successor or predecessor nodes' IDs. At this point, the current
node starts routing via its partner nodes in the next larger
proximal ring in which it participates. This process of
progressively moving towards the destination node by climbing along
the partitioning path towards the root ring terminates when the
destination node is reached.
[0042] Embodiments within the scope of the present invention
include computer-readable media for carrying or having
computer-executable instructions or data structures stored thereon.
Such computer-readable media may be any available media, which is
accessible by a general-purpose or special-purpose computer system.
By way of example, and not limitation, such computer-readable media
can comprise physical storage media such as RAM, ROM, EPROM, CD-ROM
or other optical disk storage, magnetic disk storage or other
magnetic storage devices, or any other media which can be used to
carry or store desired program code means in the form of
computer-executable instructions, computer-readable instructions,
or data structures and which may be accessed by a general-purpose
or special-purpose computer system.
[0043] In this description and in the following claims, a "network"
is defined as one or more data links (of possibly different speeds)
that enable the transport of electronic data between computer
systems and/or modules (e.g., hardware and/or software modules).
When information is transferred or provided over a network or
another communications connection (either hardwired, wireless, or a
combination of hardwired or wireless) to a computer system, the
connection is properly viewed as a computer-readable medium. Thus,
any such connection is properly termed a computer-readable medium.
Combinations of the above should also be included within the scope
of computer-readable media. Computer-executable instructions
comprise, for example, instructions and data which cause a
general-purpose computer system or special-purpose computer system
to perform a certain function or group of functions. The computer
executable instructions may be, for example, binaries, intermediate
format instructions such as assembly language, or even source code.
In some embodiments, hardware modules, such as, for example,
special purpose integrated circuits or Gate-arrays are optimized to
implement the principles of the present invention.
[0044] In this description and in the following claims, a "node" is
defined as one or more software modules, one or more hardware
modules, or combinations thereof, that work together to perform
operations on electronic data. For example, the definition of a
node includes the hardware components of a personal computer, as
well as software modules, such as the operating system of the
personal computer. The physical layout of the modules is not
important. A node can include one or more computers coupled via a
network. Likewise, a node can include a single physical device
(such as a mobile phone or Personal Digital Assistant "PDA") where
internal modules (such as a memory and processor) work together to
perform operations on electronic data. Further, a node can include
special purpose hardware, such as, for example, a router that
includes special purpose integrated circuits.
[0045] Those skilled in the art will appreciate that the invention
may be practiced in network computing environments with many types
of node configurations, including, personal computers, laptop
computers, hand-held devices, multi-processor systems,
microprocessor-based or programmable consumer electronics, network
PCs, minicomputers, mainframe computers, mobile telephones, PDAs,
pagers, routers, gateways, brokers, proxies, firewalls,
redirectors, network address translators, and the like. The
invention may also be practiced in distributed system environments
where local and remote nodes, which are linked (either by hardwired
data links, wireless data links, or by a combination of hardwired
and wireless data links) through a network, both perform tasks. In
a distributed system environment, program modules may be located in
both local and remote memory storage devices.
[0046] Federation Architecture
[0047] FIG. 1 illustrates an example of a federation infrastructure
100. The federation infrastructure 100 includes nodes 101, 102,
103, that can form different types of federating partnerships. For
example, nodes 101, 102, 103 can be federated among one another as
peers without a root node. Each of nodes 101, 102, and 103 has a
corresponding ID 171, 182, and 193 respectively.
[0048] Generally, the nodes 101, 102, 103, can utilize federation
protocols to form partnerships and exchange information (e.g.,
state information related to interactions with other nodes). The
formation of partnerships and exchange of information facilitates
more efficient and reliable access to resources. Other intermediary
nodes (not shown) can exist between nodes 101, 102, and 103 (e.g.,
nodes having IDs between 171 and 193). Thus, a message routed, for
example, between node 101 and node 103, can be pass through one or
more of the other intermediary nodes.
[0049] Nodes in federation infrastructure 100 (including other
intermediary nodes) can include corresponding rendezvous protocol
stacks. For example, nodes 101, 102, and 103 include corresponding
rendezvous protocol stacks 141, 142, and 143 respectively. Each of
the protocols stacks 141, 142, and 143 includes an application
layer (e.g., application layers 121, 122, and 123) and other lower
layers (e.g., corresponding other lower layers 131, 132, and 133).
Each layer in a rendezvous protocol stack is responsible for
different functionality related to rendezvousing a resource request
with a corresponding resource.
[0050] For example, other lower layers can include a channel layer,
a routing layer, and a function layer. Generally, a channel layer
is responsible for reliably transporting a message (e.g., using
WS-ReliableMessaging and Simple Object Access Protocol ("SOAP"))
from one endpoint to another (e.g., from node 101 to node 103). The
channel layer is also responsible for processing incoming and
outgoing reliable messaging headers and maintaining state related
to reliable messaging sessions.
[0051] Generally, a routing layer is responsible for computing the
next hop towards a destination. The routing layer is also
responsible for processing incoming and outgoing addressing and
routing message headers and maintaining routing state. Generally, a
function layer is responsible for issuing and processing rendezvous
protocol messages such as join and depart requests, pings, updates,
and other messages, as well as generation of responses to these
messages. The function layer processes request messages from the
routing layer and sends back corresponding response messages, if
any, to the originating node using the routing layer. The function
layer also initiates request messages and utilizes the routing
layer to have the requests messages delivered.
[0052] Generally, an application layer processes non-rendezvous
protocol specific data delivered from the function layer (i.e.,
application messages). The function layer can access application
data from the application layer and get and put application data in
rendezvous protocol messages (e.g., pings and updates). That is,
the function layer can cause application data to be piggybacked on
rendezvous protocol messages and can cause the application data to
be passed back to the application layer in receiving rendezvous
protocol nodes. In some embodiments, application data is used to
identify resources and resource interests. Thus, an application
layer can include application specific logic and state that
processes data received from and sent to the other lower layers for
purposes of identifying resources and resource interests.
[0053] Federating Mechanisms
[0054] Nodes can federate using a variety of different mechanisms.
A first federating mechanism includes peer nodes forwarding
information to all other peer nodes. When a node is to join a
federation infrastructure, the node utilizes a broadcast/multicast
discovery protocol, such as, for example, WS-Discovery to announce
its presence and issues a broadcast/multicast find to detect other
nodes. The node then establishes a simple forwarding partnership
with other nodes already present on the network and accepts new
partnerships with newly joining nodes. Thereafter, the node simply
forwards all application specific messages to all of its partner
nodes.
[0055] A second federating mechanism includes peer nodes that most
efficiently transmit application specific messages to their
destination(s). When a new node is to join a federation
infrastructure, the new node utilizes a broadcast/multicast
discovery protocol, such as, for example, WS-Discovery to announce
its presence and issues a broadcast/multicast find to detect other
nodes that are part of the federation infrastructure. Upon
detecting another node, the new node establishes a partnership with
the other node. From the established partnership, the new node
learns about the presence of other nodes already participating in
federation infrastructure. It then establishes partnerships with
these newly-learned nodes and accepts any new incoming partnership
requests.
[0056] Both node arrivals/departures and registrations of interest
in certain application specific messages are flooded through the
federation infrastructure resulting in every node having global
knowledge of other partner nodes and registrations of interest in
application specific messages. With such global knowledge, any node
can send application specific messages directly to the nodes that
have expressed interest in the application specific message.
[0057] A third federating mechanism includes peer nodes indirectly
forwarding all application specific messages to their
destination/s. In this third mechanism, nodes are assigned
identifiers (ID's), such as, for example, a 128-bit or 160-bit ID.
The node responsible for a maintaining registration of interest in
a given application specific message can be determined to be the
one whose ID is closest to the one obtained by mapping (e.g.,
hashing) the destination identity (e.g. URI) of the application
specific message to this 128-bit or 160-bit ID-space.
[0058] In this third mechanism, node arrivals and departures are
flooded over the entire fabric. On the other hand, registrations of
interest in certain application specific messages are forwarded to
the nodes determined to be responsible for maintaining such
registration information. For scalability, load balancing, and
fault-tolerance, the node receiving registration of interest in
certain application specific messages can reliably flood that
registration information within its neighborhood set. The
neighborhood set for a specified node can be determined to be the
set of nodes having IDs within a predefined range on either side of
the ID of specified node.
[0059] Similar to the second mechanism, a newly joining node
utilizes a broadcast/multicast discovery protocol, such as, for
example, WS-Discovery to announce its presence and issues a local
broadcast/multi-cast find to detect a node that is already part of
the federation infrastructure. The new node establishes a
partnership with the discovered node and uses that partnership to
learn about the presence of other new nodes participating in the
federation infrastructure. The new node then establishes further
partnerships with the newly discovered nodes and accepts any new
incoming partnership requests. The new node accepts incoming
registrations of interest in certain application layer specific
resources from its partners for which it is responsible and may
flood them over its neighborhood set. Thus, messages can generally
be forwarded to their final destination via intermediary routing
nodes (e.g., that a newly joining node has partnered with or that a
partner node is aware of).
[0060] In response to receiving an incoming application specific
message, the new node forwards the message to the partner node that
may be responsible for maintaining the registration information for
the destination specified in the message. Thus, when using this
third mechanism, every node in the federation infrastructure has
global knowledge of all other nodes but the registration
information is efficiently partitioned among the nodes. Application
specific messages are transmitted to their final destination via
only the partner's nodes that may have the responsibility for
maintaining registration information of interest in those
application specific messages. Thus, indirection is accomplished by
forwarding only to the partner node that has global knowledge of
the registration information of interest for the message being
processed. This is in contrast to the first mechanism where the
indirection is accomplished by forwarding to all the partner
nodes.
[0061] A fourth federating mechanism includes peer nodes that route
messages to other peer nodes. This fourth mechanism differs from
the third mechanism at least in that both node arrivals/departures
and registrations of interest in certain application specific
messages are all routed instead being flooded. Routing protocols
are designed to guarantee rendezvous between application specific
messages and the registration messages that express interest in
those application specific messages.
[0062] FIG. 2 illustrates an example of a computer architecture 200
that facilitates routing requests indirectly to partners. Computer
architecture 200 depicts different types of computer systems and
devices potentially spread across multiple local discovery scopes
participating in a federation infrastructure.
[0063] Workstation 233 can include a registered PnP provider
instance. To inform its partners of the presence of this PnP
provider instance, workstation 233 routes registration request 201
over the federation infrastructure. Registration request 201 is
initially forwarded to laptop 231, which in turn forwards
registration request 201 to message broker 237, which in turn
forwards registration request 201 to message gateway 241. Message
gateway 241 saves the registration information registration request
201 in its database and returns success message 204 to workstation
233.
[0064] Subsequently, another registered provider instance, this
time that of running services, comes alive within the workstation
233. This time the node is aware that message gateway 241 is
responsible for registrations and forwards registration request 205
to message gateway 241 directly. Message gateway 241 saves the
registration information registration request 205 in its database
and returns success message 206 to workstation 233.
[0065] Subsequently, the printer 236 (e.g., a UPnP printer) is
powered on and sends announcement 207. Server 234 detects
announcement 207 and routes registration request 208 to message
broker 237. Message broker 237 forwards registration request 208 to
message gateway 241. Message gateway 241 saves the registration
information registration request 208 in its database and returns
success message 210 to server 234.
[0066] Subsequently, personal computer 242 issues lookup request
211 to discover all devices. Since personal computer 242 doesn't
know where to forward lookup request 211, it routes lookup request
211 through workstation 243. As registration and lookup requests
are routed to the same destination, the routing protocol
essentially guarantees rendezvous between the two requests
resulting in workstation 243 forwards find request 211 to message
gateway 241. Message gateway 241 looks up the registration
information maintained by it and forwards find request 211 to both
the workstation 233 and server 234. Workstation 233 and server 234
send response messages 214 and 216 respectively to personal
computer 242.
[0067] This fourth mechanism works by routing (instead of flooding)
a request to the node (message gateway 241) that has global
knowledge of the registrations specified in a request. This fourth
mechanism, as will be described in further detail below,
essentially guarantees that routing can be accomplished in O(log N)
hops, where N is the number of nodes participating in the
federation infrastructure. Since this fourth mechanism efficiently
partitions both node partnership and registration information, it
scales to very large networks, even the Internet.
[0068] Although a number of federating mechanisms have been
described, it would be apparent to one skilled in the art, after
having reviewed this description, that other federation mechanisms
are possible.
[0069] Relationship Between Nodes in a Federation
[0070] Accordingly, a federation consists of a set of nodes that
cooperate among themselves to form a dynamic and scalable network
in which information can be systematically and efficiently
disseminated and located. Nodes are organized to participate in a
federation as a sorted list using a binary relation that is
reflexive, anti-symmetric, transitive, total, and defined over the
domain of node identities. Both ends of the sorted list are joined,
thereby forming a ring. Thus, each node in the list can view itself
as being at the middle of the sorted list (as a result of using
modulo arithmetic). Further, the list is doubly linked so that any
node can traverse the list in either direction.
[0071] Each federating node can be assigned an ID (e.g., by a
random number generator with duplicate detection) from a fixed set
of IDs between 0 and some fixed upper bound. Thus, adding 1 to an
ID of the fixed upper bound results in an ID of zero (i.e., moving
from the end of the linked list back to the beginning of the linked
listed. In addition, a 1:1 mapping function from the value domain
of the node identities to the nodes themselves is defined.
[0072] FIG. 3 depicts an example linked list 304 and corresponding
ring 306. Given such a ring, the following functions can be
defined: [0073] RouteNumerically(V, Msg): Given a value V from the
value domain of node identities and a message "Msg," deliver the
message to node X whose identity can be mapped to V using the
mapping function. [0074] Neighborhood(X, S): Neighborhood is the
set of nodes on the either side of node X with cardinality equal to
S.
[0075] When every node in the federation has global knowledge of
the ring, RouteNumerically(V, Msg) is implemented by directly
sending Msg to the node X, whose identity is obtained by applying
the mapping function to V. Alternately, when nodes have limited
knowledge of other nodes (e.g., only of immediately adjacent
nodes), RouteNumerically(V, Msg) is implemented by forwarding the
message to consecutive nodes along the ring until it reaches the
destination node X.
[0076] Alternately (and advantageously), nodes can store enough
knowledge about the ring to perform a distributed binary search
(without having to have global knowledge or implement routing
between immediately adjacent nodes). The amount of ring knowledge
is configurable such that maintaining the ring knowledge has a
sufficiently small impact on each node but allows increased routing
performance from the reduction in the number of routing hops.
[0077] As previously described, IDs can be assigned using the
"<" (less than) relation defined over a sufficiently large,
bounded set of natural numbers, meaning its range is over a finite
set of numbers between 0 and some fixed value, inclusive. Thus,
every node participating in the federation is assigned a natural
number that lies between 0 and some appropriately-chosen upper
bound, inclusive. The range does not have to be tight and there can
be gaps between numbers assigned to nodes. The number assigned to a
node serves as its identity in the ring. The mapping function
accounts for gaps in the number space by mapping a number falling
in between two node identities to the node whose identity is
numerically closest to the number.
[0078] This approach has a number of advantages. By assigning each
node a uniformly-distributed number, there is an increased
likelihood that all segments of the ring are uniformly populated.
Further, successor, predecessor, and neighborhood computations can
be done efficiently using modulo arithmetic.
[0079] In some embodiments, federating nodes are assigned an ID
from within an ID space so large that the chances of two nodes
being assigned the same ID are highly unlikely (e.g., when random
number generation is used). For example, a node can be assigned an
ID in the range of 0 to b.sup.n-1, where b equals, for example, 8
or 16 and n equals, for example, 128-bit or 160-bit equivalent
digits. Accordingly, a node can be assigned an ID, for example,
from a range of 0 to 16.sup.40-1 (or approximately 1.461502E48).
The range of 0 to 16.sup.40-1 would provide, for example, a
sufficient number of IDs to assign every node on the Internet a
unique ID.
[0080] Thus, each node in a federation can have: [0081] An ID which
is a numerical value uniformly distributed in the range of 0 to
b.sup.n-1; and [0082] A routing table consisting of (all arithmetic
is done modulo b.sup.n): [0083] Successor node (s); [0084]
Predecessor node (p); [0085] Neighborhood nodes (p.sub.k, . . . ,
p.sub.1, p, s, s.sub.1, . . . , s.sub.j) such that Neighborhood
nodes s.sub.j.s.id>(id+u/2), j.gtoreq.v/2-1, and
p.sub.k.p.id<(id-u/2), and k.gtoreq.v/2-1; and [0086] Routing
nodes (r.sub.-(n-1), . . . , r.sub.-1, r.sub.1, . . . , r.sub.n-1)
such that r.sub..+-.i=RouteNumerically(id.+-.b.sup.i, Msg). where b
is the number base, n is the field size in number of digits, u is
the neighborhood range, v is the neighborhood size, and the
arithmetic is performed modulo b.sup.n. For good routing efficiency
and fault tolerance, values for u and v can be u=b and
v.gtoreq.max(log.sub.2(N), 4), where N is the total number of nodes
physically participating in the federation. N can be estimated from
the number of nodes present on a ring segment whose length is
greater than or equal to b, for example, when there is a uniform
distribution of IDs. Typical values for b and n are b=8 or 16 and
n=128-bit or 160-bit equivalent digits.
[0087] Accordingly, routing nodes can form a logarithmic index
spanning a ring. Depending on the locations of nodes on a ring, a
precise logarithmic index is possible, for example, when there is
an existing node at each number in the set of id.+-.b.sup.i where
i=(1, 2, . . . (n-1)). However, it may be that there are not
existing nodes at each number in the set. IN those cases, a node
closest to id.+-.b.sup.i can be selected as a routing node. The
resulting logarithmic index is not precise and may even lack unique
routing nodes for some numbers in the set.
[0088] Referring again to FIG. 3, FIG. 3 illustrates an example of
a binary relation between nodes in a federation infrastructure in
the form of sorted list 304 and corresponding ring 306. The ID
space of sorted list 304 is in the range 0 to 2.sup.8-1 (or 255).
That is, b=2 and n=8. Thus, nodes depicted in FIG. 3 are assigned
IDs in a range from 0 to 255. Sorted list 304 utilizes a binary
relation that is reflexive, anti-symmetric, transitive, total, and
defined over the domain of node identities. Both ends of sorted
list 304 are joined, thereby forming ring 306. This makes it
possible for each node in FIG. 3 to view itself as being at the
middle of sorted list 304. The sorted list 304 is doubly linked so
that any node can traverse the sorted list 304 in either direction.
Arithmetic for traversing sorted list 304 (or ring 306) is
performed modulo 2.sup.8. Thus, 255 (or the end of sorted list
304)+1=0 (or the beginning of sorted list 304).
[0089] The routing table indicates that the successor to ID 64 is
ID 76 (the ID immediately clockwise from ID 64). The successor can
change, for example, when a new node (e.g., with an ID of 71) joins
or an existing node (e.g., ID 76) leaves the federation
infrastructure. Likewise, the routing table indicates that the
predecessor to ID 64 is ID 50 (the ID immediately counters
clockwise from ID 64). The predecessor can change, for example,
when a new node (e.g., with an ID of 59) joins or an existing node
(e.g., ID 50) leaves the federation infrastructure.
[0090] The routing table further indicates that a set of
neighborhood nodes to ID 64 have IDs 83, 76, 50 and 46. A set of
neighbor nodes can be a specified number of nodes (i.e.,
neighborhood size v) that are within a specified range (i.e.,
neighbor range u) of ID 64. A variety of different neighborhood
sizes and neighbor ranges, such as, for example, V=4 and U=10, can
potentially be used to identify the set of neighborhood nodes. A
neighborhood set can change, for example, when nodes join or leave
the federation infrastructure or when the specified number of nodes
or specified range is changed.
[0091] The routing table further indicates that ID 64 can route to
nodes having IDs 200, 2, 30, 46, 50, 64, 64, 64, 64, 76, 83, 98,
135, and 200. This list is generated by identifying the node
closest to each number in the set of id.+-.2.sup.i where i=(1, 2,
3, 4, 5, 6, 7). That is, b=2 and n=8. For example, the node having
ID 76 can be identified from calculating the closest node to
64+2.sup.3, or 72.
[0092] A node can route messages (e.g., requests for access to
resources) directly to a predecessor node, a successor node, any
node in a set of neighborhood nodes, or any routing node. In some
embodiments, nodes implement a numeric routing function to route
messages. Thus, RouteNumerically(V, Msg) can be implemented at node
X to deliver Msg to the node Y in the federation whose ID is
numerically closest to V, and return node Y's ID to node X. For
example, the node having ID 64 can implement RouteNumerically(243,
Msg) to cause a message to be routed to the node having ID 250.
However, since ID 250 is not a routing node for ID 64, ID 64 can
route the message to ID 2 (the closest routing node to 243). The
node having ID 2 can in turn implement RouteNumerically(243, Msg)
to cause the message to be routed (directly or through further
intermediary nodes) to the node having ID 250. Thus, it may be that
a RouteNumerically function is recursively invoked with each
invocation routing a message closer to the destination.
[0093] Advantageously, other embodiments of the present invention
facilitate partitioning a ring into a ring of rings or tree of
rings based on a plurality of proximity criteria of one or more
proximity categories (e.g., geographical boundaries, routing
characteristics (e.g., IP routing hops), administrative domains,
organizational boundaries, etc.). It should be understood a ring
can be partitioned more than once using the same type of proximity
criteria. For example, a ring can be partition based on a continent
proximity criteria and a country proximity criteria (both of a
geographical boundaries proximity category).
[0094] Since IDs can be uniformly distributed across an ID space (a
result of random number generation) there is a high probability
that any given segment of a circular ID space contains nodes that
belong to different proximity classes provided those classes have
approximately the same cardinality. The probability increases
further when there are a sufficient number of nodes to obtain
meaningful statistical behavior.
[0095] Thus, neighborhood nodes of any given node are typically
well dispersed from the proximality point of view. Since published
application state can be replicated among neighborhood nodes, the
published information can be well dispersed as well from the
proximality point of view.
[0096] FIG. 4 illustrates a ring of rings 400 that facilitates
proximal routing. Ring 401 can be viewed as a master or root ring,
and contains all the nodes in each of the rings 402, 403, and 404.
Each of the rings 402, 403, and 404 contain a subset of nodes from
ring 401 that are partitioned based on a specified proximity
criterion. For example, ring 401 may be partitioned based on
geographic location, where ring 402 contains nodes in North
America, ring 403 contains nodes in Europe, and ring 404 contains
nodes in Asia.
[0097] In a numerical space containing 65,536 (2.sup.16) IDs,
routing a message from a North American node having an ID 5,345 to
an Asian node having an ID 23,345 can include routing the message
within ring 402 until a neighbor node of the Asian node is
identified. The neighbor node can then route the message to the
Asian node. Thus, a single hop (as opposed to multiple hops) is
made between a North American node and an Asian node. Accordingly,
routing is performed in a resource efficient manner.
[0098] FIG. 5 illustrates an example proximity induced partition
tree of rings 500 that facilitates proximal routing. As depicted,
partition tree of rings 500 includes a number of rings. Each of the
rings represents a partition of a sorted linked list. Each ring
including a plurality a nodes having IDs in the sorted linked list.
However for clarity due to the number of potential nodes, the nodes
are not expressly depicted on the rings (e.g., the ID space of
partition tree 500 may be b=16 and n=40).
[0099] Within partition tree 500, root ring 501 is partitioned into
a plurality of sub-rings, including sub-rings 511, 512, 513, and
514, based on criterion 571 (a first administrative domain boundary
criterion). For example, each component of a DNS name can be
considered a proximity criterion with the partial order among them
induced per their order of appearance in the DNS name read right to
left. Accordingly, sub-ring 511 can be further partitioned into a
plurality of sub-rings, including sub-rings 521, 522, and 523,
based on criterion 581 (a second administrative domain boundary
criterion).
[0100] Sub-ring 522 can be further partitioned into a plurality of
sub-rings, including sub-rings 531, 532, and 533, based on
criterion 572 (a geographic boundary criterion). Location based
proximity criterion can be partially ordered along the lines of
continents, countries, postal zip codes, and so on. Postal zip
codes are themselves hierarchically organized meaning that they can
be seen as further inducing a partially ordered sub-list of
proximity criteria.
[0101] Sub-ring 531 can be further partitioned into a plurality of
sub-rings, including sub-rings 541, 542, 543, and 544, based on
criterion 573 (a first organizational boundary criterion). A
partially ordered list of proximity criterion can be induced along
the lines of how a given company is organizationally structured
such as divisions, departments, and product groups. Accordingly,
sub-ring 543 can be further partitioned into a plurality of
sub-rings, including sub-rings 551 and 552, based on criterion 583
(a second organizational boundary criterion).
[0102] Within partition tree 500, each node has a single ID and
participates in rings along a corresponding partition path starting
from the root to a leaf. For example, each node participating in
sub-ring 552 would also participate in sub-rings 543, 531, 522, 511
and in root 501. Routing to a destination node (ID) can be
accomplished by implementing a RouteProximally function, as
follows: [0103] RouteProximally(V, Msg, P): Given a value V from
the domain of node identities and a message "Msg," deliver the
message to the node Y whose identity can be mapped to V among the
nodes considered equivalent by the proximity criteria P.
[0104] Thus, routing can be accomplished by progressively moving
closer to the destination node within a given ring until no further
progress can be made by routing within that ring as determined from
the condition that the destination node lies between the current
node and its successor or predecessor node. At this point, the
current node starts routing via its partner nodes in the next
larger ring in which it participates. This process of progressively
moving towards the destination node by climbing along the
partitioning path towards the root ring terminates when the closest
node to the destination node is reached within the requested
proximal context, as originally specified in the RouteProximally
invocation.
[0105] Routing hops can remain in the proximal neighborhood of the
node that originated the request until no further progress can be
made within that neighborhood because the destination node exists
outside it. At this point, the proximity criterion is relaxed to
increase the size of the proximal neighborhood to make further
progress. This process is repeated until the proximal neighborhood
is sufficiently expanded to include the destination node (ID). The
routing hop made after each successive relaxation of proximal
neighborhood criterion can be a potentially larger jump in proximal
space while making a correspondingly smaller jump in the numerical
space compared to the previous hop. Thus, only the absolutely
required number of such (inter-ring) hops is made before the
destination is reached.
[0106] It may be the case that some hops are avoided for lookup
messages since published application data gets replicated down the
partition tree when it is replicated among the neighborhood nodes
of the destination node.
[0107] To accomplish proximal routing, each federation node
maintains references to its successor and predecessor nodes in all
the rings it participates as a member (similar to successor and
predecessor for a single ring)--the proximal predecessor, proximal
successor, and proximal neighborhood. In order to make the routing
efficient, the nodes can also maintain reference to other nodes
closest to an exponentially increasing distance on its either half
of the ring as routing partners (similar to routing nodes for a
single ring). In some embodiments, routing partner nodes that lie
between a pair of consecutive successor or predecessor nodes
participate in the same lowest ring shared by the current node and
the node numerically closest to it among the successor or
predecessor node pairs respectively. Thus, routing hops towards a
destination node transition into using a relaxed proximity
criterion (i.e., transitioning to a higher ring) only when
absolutely needed to make further progress. Accordingly, messages
can be efficiently rendezvoused with a corresponding federation
node.
[0108] In some embodiments, nodes implement a proximal routing
function to route messages based on equivalence criteria relations.
Thus, given a number V and a message "Msg", a node can implement
RouteProximally(V, Msg, P) to deliver the message to the node Y
whose identify can be mapped to V among the nodes considered
equivalent by proximity criterion P. The proximity criterion P
identifies the lowest ring in the partition tree that is the common
ancestor to all the nodes considered proximally equivalent by it.
It can be represented as a string obtained by concatenating the
proximity criterion found along the path from the root ring to the
ring identified by it separated by the path separator character
`/`. For example, the proximity criterion identifying sub-ring 542
can be represented as "Proximity:/.COM/Corp2/LocationA/Div2". Each
ring in the partition tree 500 can be assigned a unique number, for
example, by hashing its representational string with a SHA based
algorithm. If the number 0 is reserved for the root ring, it can be
inferred that RouteNumerically(V, Msg).ident.RouteProximally(V,
Msg, 0).
[0109] For example, a node in sub-ring 544 can implement
RouteProximally to identify a closer node in sub-ring 531 (e.g., to
a node in sub-ring 513). In turn, sub-ring 531 can implement
RouteProximally to identify a closer node in sub-ring 522.
Likewise, sub-ring 522 can implement RouteProximally to identify a
closer node in sub-ring 511. Similarly, sub-ring 511 can implement
RouteProximally to identify a closer node in ring 501. Thus, it may
be that a RouteProximally function is recursively invoked with each
invocation routing a message closer to the destination.
[0110] Thus, when proximity criterion is taken into account,
routing hops on a path to a final destination can remain within the
proximity of a node that originates a request, while making
significant progress between the originating node and the
destination node in a numerical space, until either the destination
node is reached or no further progress can be made under the chosen
proximity criterion at which point it is relaxed just enough to
make further progress towards the destination. For example,
proximity criterion can be relaxed enough for a message to be
routed from ring 531 up to ring 522, etc.
[0111] Utilizing the above approach to proximity, it is possible to
confine published information to a given ring. For example,
organizations may like to ensure that organization specific
information is not available to entities outside of their trust
domains either (1) implicitly in the form of neighborhood
replication to nodes outside of their domains or (2) explicitly in
the form of servicing lookup requests for such information. The
first aspect is satisfied by replicating published information only
among the nodes neighboring the target ID within the specified
ring. Because all messages originated by a node are routed by
successively climbing the rings to which it belongs towards the
root ring, there is a high likelihood that all lookup requests
originated within an organization will be able to locate the
published information confined to it thereby implicitly satisfying
the second aspect.
[0112] Also, organizations dislike nodes automatically federating
with nodes outside of their trust domain. This can happen, for
example, when a visiting sales person connects his/her laptop
computer to the network in the customer premises. Ideally, the
laptop computer belonging to the sales person wishes to locate
information published in its home domain and/or federate with the
nodes in its home domain starting at its lowest preferred proximity
ring. It will typically not be permitted to federate with the nodes
in the customer's domain. Supporting this scenario requires ability
to locate seed nodes in the home domain. Such seed nodes can be
used for locating information published in the home domain, to join
the home federation, and selectively import and export published
information across domains. Seed nodes are also sometimes referred
as message gateways.
[0113] In other embodiments, an entity publishes references to seed
nodes in the root ring. Seed nodes can be published at the unique
number (such as the one obtained by hashing its representational
string) associated with the ring (as a target ID). Seed node
information can further be on-demand cached by the nodes in various
rings that are on the path to the corresponding target IDs in the
root ring. Such on-demand caching provides for improved performance
and reduction in hotspots that might occur when semi-static
information is looked up quite frequently. Seed node information
can also be obtained via other means such as DNS
[0114] To provide fault tolerance for confined published
information, each node can maintain a set of neighborhood nodes in
all of the rings it participates in. Given the above, the state
maintained by a node can be summarized as follows: [0115] An ID
which is a numerical value uniformly distributed in the range of 0
to b.sup.n-1. [0116] A routing table consisting of (all arithmetic
is done modulo b.sup.n): [0117] For each ring, say ring d, in which
the node participates [0118] Successor node (s.sub.d) [0119]
Predecessor node (p.sub.d) [0120] Neighborhood nodes (p.sub.kd, . .
. , p.sub.1d, p.sub.d, s.sub.d, s.sub.1d, . . . , s.sub.jd) such
that s.sub.jd.s.sub.d.id>(id+u/2), j.gtoreq.v/2-1,
p.sub.kd.p.sub.d.id<(id-u/2), and k.gtoreq.v/2-1. [0121] Routing
nodes (r.sub.-(n-1), . . . , r.sub.-1, r.sub.1, . . . , r.sub.n-1)
such that r.sub..+-.i==RouteProximally(id.+-.b.sup.i, updateMsg, d)
such that s.sub.d.ltoreq.id+b.sup.i.ltoreq.s.sub.d+1 or
p.sub.d+1.ltoreq.id-b.sup.i.ltoreq.p.sub.d as appropriate. [0122]
where b is the number base, n is the field size in number of
digits, u is the neighborhood range, and v is the neighborhood
size.
[0123] Note that a subset of the neighborhood nodes maintained by a
given node in ring "d" can appear again as neighborhood nodes in
the child ring "d+1" in which the given node participates as well.
As such one can derive the upper bound on the total number of
neighborhood nodes maintained by a given node across all the D
rings it participates as D*max(u,v)/2. This considers that only one
reference to a given node is kept and the worst case upper bound is
for a balanced tree.
[0124] It should be noted that when a ring is partitioned into a
plurality of corresponding sibling sub-rings, it is permitted for a
specified node to simultaneously participate in more than one of
the plurality of corresponding sibling sub-rings, for example,
through aliasing. Aliasing can be implemented to associate
different state, for example, from different sub-rings, with the
specified node. Thus, although aliases for a given node have the
same ID, each alias can have distinct state associated with them.
Aliasing allows the specified node to participate in multiple rings
having distinct proximity criteria that are not necessarily common
ancestors of more specific proximity criteria. That is, the
specified node can participate in multiple branches of the
proximity tree.
[0125] For example, a dual NIC (wired and wireless) laptop can be
considered to be proximally equivalent to both other wireless and
wired nodes sharing the same LAN segments as the laptop. But, these
two distinct proximity criteria can be modeled as sub-criteria that
are applicable only after application of a different higher
priority proximity criterion, such as, for example, one based on
organizational membership. As the laptop belongs to the same
organization, the aliased nodes in the two sub-rings representing
1) membership in the wired and 2) membership in the wireless LAN
segments merge into a single node in the ring representing the
organization to which the laptop belongs. It should be understand
that the RouteProximally works as expected without any
modifications in the presence of aliasing.
[0126] Each proximal ring can be configured in accordance with
(potentially different) ring parameters. Ring parameters can be
used to define a neighborhood (e.g., ring parameters can represent
a neighborhood range, a neighborhood size, ping message and depart
message timing and distribution patterns for ping and depart
messages), indicate a particular federating mechanisms (e.g., from
among the above-described first through fourth federating
mechanisms previously described or from among other federating
mechanisms), or define communication specifics between routing
partners in the same proximal ring. Some ring parameters may be
more general, applying to a plurality of different federating
mechanisms, while other ring parameters are more specific and apply
to specific type of federating mechanism.
[0127] Ring parameters used to configure a higher level proximal
ring can be inherited in some embodiments by lower level proximal
rings. For example, it may be that ring 543 inherits some of the
ring parameters of ring 531 (which in turn inherited from ring 522,
etc.). Thus, a neighborhood size and neighborhood range associated
with ring 531 is also associated with ring 541.
[0128] However, inherited ring parameters can be altered and/or
proximal rings can be individually configured in accordance with
different ring parameters. For example, it may be that ring 511 is
for an administrative domain that contains a large number of nodes
and thus the above-described fourth federating mechanism is more
appropriate for ring 511. On the other hand, it may be that ring
521 is for a small business with a relatively smaller number of
nodes and thus the above-described second federating mechanism is
more appropriate for ring 521. Thus, the ring parameters associated
with ring 521 can be set to (or inherited parameters changed to)
different values than the ring parameters associated with ring 511.
For example, a ring parameter indicating a particular type of
federating mechanisms can be different between rings 511 and 521.
Similarly parameters defining a neighborhood can be different
between rings 511 and 521. Further, ring 521 can be configured in
accordance with specific parameters that are specific to the
above-described second federating mechanism, while ring 511 is
configured in accordance additional with specific parameters that
are specific to the above-described fourth federating
mechanism.
[0129] Accordingly, proximal rings can be flexibly configured based
on the characteristics (e.g., number, included resources, etc.) of
nodes in the proximal rings. For example, an administrator can
select ring parameters for proximal rings using a configuration
procedure (e.g., through a user-interface). A configuration
procedure can facilitate the configuration of inheritance
relationships between proximal rings as well as the configuration
of individual proximal rings, such as, for example, to override
otherwise inherited ring parameters.
[0130] FIG. 8 illustrates an example flow chart of a method 800 for
partitioning the nodes of a federation infrastructure. The method
800 will be described with respect to the rings of partition a tree
500 in FIG. 5. Method 800 includes an act of accessing a sorted
linked list containing node IDs that have been assigned to nodes in
a federation infrastructure (act 801). For example, the sorted
linked list represented by ring 501 can be accessed. The node IDs
of the sorted linked list (the nodes depicted on ring 501) can
represent nodes in a federation infrastructure (e.g., federation
infrastrucre 100).
[0131] Method 800 includes an act of accessing proximity categories
that represent a plurality of different proximity criteria for
partitioning the sorted linked list (act 802). For example,
proximity criterion representing domain boundaries 561,
geographical boundaries 562, and organizational boundaries 563 can
be accessed. However, other proximity criteria, such as, trust
domain boundaries, can also be represented in accessed proximity
criterion. Proximity categories can include previously created
partially ordered lists of proximity criteria. A ring can be
partitioned based on partially ordered lists of proximity
criteria.
[0132] Method 800 includes an act of partitioning the sorted link
list into one or more first sub lists based on a first proximity
criterion, each of the one or more first sub lists containing at
least a subset of the node IDs from the sorted linked list (act
803). For example, ring 501 can be partitioned into sub-rings 511,
512, 513, and 514 based on criterion 571. Each of sub-rings 511,
512, 513, and 514 can contain a different sub-set of node IDs from
ring 501.
[0133] Method 800 includes an act of partitioning a first sub list,
selected from among the one or more first sub lists, into one or
more second sub lists based on a second proximity criterion, each
of the one or more second sub lists containing at least a subset of
node IDs contained in the first sub list (act 804). For example,
sub-ring 511 can be partitioned into sub-rings 521, 522, and 523
based on criterion 581. Each of he sub-rings 521, 522, and 523 can
contain a different sub-set of node IDs from sub-ring 511.
[0134] FIG. 9 illustrates an example flow chart of a method 900 for
populating a node's routing table. The method 900 will be described
with respect to the sorted linked list 304 and ring 306 in FIG. 3.
Method 900 includes an act of inserting a predecessor node into a
routing table, the predecessor node preceding a current node
relative to the current node in a first direction of a sorted
linked list (act 901). For example, the node having ID 50 can be
inserted into the routing table as a predecessor for the node
having ID 64 (the current node). Moving in a clockwise direction
321 (from end A of sorted linked list 304 towards end B of sorted
linked list 304), the node having ID 50 precedes the node having ID
64. Inserting a predecessor node can establish a symmetric
partnership between the current node and the predecessor node such
that current node is a partner of predecessor node and the
predecessor node is a partner of the current node
[0135] Method 900 includes an act of inserting a successor node
into the routing table, the successor node succeeding the current
node relative to the current node in the first direction in the
sorted linked list (act 902). For example, the node having ID 76
can be inserted into the routing table as a successor for the node
having ID 64 (the current node). Moving in a counter-clockwise
direction 322, the node having ID 76 succeeds the node having ID
64. Inserting a successor node can establish a symmetric
partnership between the current node and the successor node such
that current node is a partner of the successor node and the
successor node is a partner of the current node.
[0136] Method 900 includes an act of inserting appropriate
neighborhood nodes into the routing table, the neighborhood nodes
identified from the sorted linked list in both the first direction
and in a second opposite direction based on a neighborhood range
and neighborhood size (act 903). For example, the nodes having IDs
83, 76, 50, and 46 can be inserted into the routing table as
neighborhood nodes for the node having ID 64 (the current node).
Based on a neighborhood range of 20 and a neighborhood size 4, the
nodes having IDs 83 and 76 can be identified in clockwise direction
321 and the nodes having IDs 50 and 46 can be identified in
counter-clockwise direction 322 (moving from end B of sorted linked
list 304 towards end A of sorted linked list 304). It may be that
in some environments no appropriate neighborhood nodes are
identified. Inserting a neighborhood node can establish a symmetric
partnership between the current node and the neighborhood node such
that current node is a partner of the neighborhood node and the
neighborhood node is a partner of the current node.
[0137] Method 900 includes an act of inserting appropriate routing
nodes into the routing table, the routing nodes identified from the
sorted linked list in both the first and second directions based on
the a number base and field size of the ID space for the federation
infrastructure, the routing nodes representing a logarithmic index
of the sorted link list in both the first and second directions
(act 904). For example, the nodes having IDs 200, 2, 30, 46, 50,
64, 64, 64, 64, 64, 76, 83, 98, 135 and 200 can be inserted into
the routing table as routing nodes for the node having ID 64. Based
on the number base 2 and field size of 8 the nodes having IDs 64,
64, 76, 83, 98, 135 and 200 can be identified in direction 321 and
the nodes having IDs 64, 64, 50, 46, 30, 2, and 200 can be
identified in direction 322. As depicted inside ring 306, the
routing nodes represent a logarithmic index of the sorted link list
304 in both clockwise direction 321 and counter-clockwise direction
322. Inserting a routing node can establish a symmetric partnership
between the current node and the routing node such that current
node is a partner of the routing node and the routing node is a
partner of the current node.
[0138] FIG. 7 illustrates an example flow chart of a method 700 for
populating a node routing table that takes proximity criteria into
account. The method 700 will be described with respect to the rings
in FIG. 5. Method 700 includes an act of inserting a predecessor
node for each hierarchically partitioned routing ring the current
node participates in into a routing table (act 701). Each
predecessor node precedes the current node in a first direction
(e.g., clockwise) within each hierarchically partitioned routing
ring the current node participates in. The hierarchically
partitioned routing rings are partitioned in accordance with
corresponding proximity criteria and contain at least subsets of a
bi-directionally linked list (and possibly the whole
bi-directionally linked list). For example, it may be that a
specified node participates in root ring 501 and sub-rings 511,
522, 523, 531, and 542. Thus, a predecessor node is selected for
the specified node from within each of the rings 501 and sub-rings
511, 522, 523, 531, and 542.
[0139] Method 700 includes an act of inserting a successor node for
each hierarchically partitioned routing ring the current node
participates in into the routing table (act 702). Each successor
node succeeding the current node in the first direction within each
hierarchically partitioned routing ring the current node
participates in. For example, a successor node is selected for the
specified node from within each of the rings 501 and sub-rings 511,
522, 523, 531, and 542.
[0140] Method 700 includes an act of inserting appropriate
neighborhood nodes for each hierarchically partitioned routing ring
the current node participates in into the routing table (act 703).
The neighborhood nodes can be identified in both the first
direction (e.g., clockwise) and in a second opposite direction
(e.g., counter clockwise) based on a neighborhood range and
neighborhood size from the hierarchically partitioned routing rings
the current node participates in. For example, neighborhood nodes
can be identified for the specified node from within each of the
rings 501 and sub-rings 511, 522, 523, 531, and 542.
[0141] Method 700 includes an act of inserting appropriate routing
nodes for each hierarchically partitioned routing ring the current
node participates in into the routing table (act 704). For example,
routing nodes can be identified for the specified node from within
each of the rings 501 and sub-rings 511, 522, 523, 531, and
542.
[0142] In some embodiments, appropriate routing nodes are inserted
for each proximity ring d except the leaf ring (or leaf rings in
embodiments that utilize aliasing), in which the node Y
participates. Appropriate routing nodes can be inserted based on
the following expression(s):
[0143] if Y.s.sub.d.id<Y.id+b.sup.i<Y.s.sub.d+1.id is true,
then use ring d; or
[0144] if Y.p.sub.d.id<Y.id-b.sup.i<Y.p.sub.d+1.id is true,
then use ring d.
[0145] If a ring has not been identified in the previous step, use
the lead (e.g., ring 501) ring as ring d. Now, ring d is the
proximity ring in which node Y should look for the routing partner
closest to z.
[0146] FIG. 10 illustrates an example flow chart of a 1000 method
for routing a message towards a destination node. The method 1000
will be described with respect to the sorted linked list 304 and
ring 306 in FIG. 3. Method 1000 includes an act of a receiving node
receiving a message along with a number indicating a destination
(act 1001). For example, the node having ID 64 can receive a
message indicating a destination of 212.
[0147] Method 1000 includes an act of determining that the
receiving node is at least one of numerically further from the
destination than a corresponding predecessor node and numerically
further from the destination than a corresponding successor node
(act 1002). For example, in direction 322, ID 64 is further from
destination 212 than ID 50 and, in direction 321, ID 64 is further
from destination 212 than ID 76. Method 1000 includes an act of
determining that the destination is not within a neighborhood set
of nodes corresponding to the receiving node (act 1003). For
example, the node with ID 64 can determine that destination 212 is
not within the neighborhood set of 83, 76, 50, and 46.
[0148] The method 1000 includes an act of identifying an
intermediate node from a routing table corresponding to the
receiving node, the intermediate node being numerically closer to
the destination than other routing nodes in the corresponding
routing table (act 1004). For example, the node having ID 64 can
identify the routing node having ID 200 as being numerically closer
to destination 212 that other routing nodes. The method 1000
includes an act of sending the message to the intermediate node
(act 1005). For example, the node having ID 64 can send the message
to the node having ID 200.
[0149] FIG. 11 illustrates an example flow chart of a method 1100
for routing a message towards a destination node based on proximity
criteria. The method 1100 will be described with respect to the
rings in FIG. 4 and FIG. 5. Method 1100 includes an act of a
receiving node receiving a message along with a number indicating a
destination and a proximity criterion (act 1101). The proximity
criterion defines one or more classes of nodes. The receiving node
receives the message as part of a current class of nodes selected
form among the one or more classes of nodes based on the proximity
criterion. For example, the node having ID 172 can receive a
message indicating a destination of 201 and proximity criterion
indicating that the destination node be part of classes represented
by ring 401. The node having ID 172 can receive the message as part
of ring 404.
[0150] Method 1100 includes an act of determining that the
receiving node is at least one of, numerically further from the
destination than a corresponding predecessor node and numerically
further from the destination than a corresponding successor node,
among nodes in a selected class of nodes (act 1102). For example,
within ring 404, the node with ID 172 is further from destination
201 than the node having ID 174 in the clockwise direction and is
further from destination 201 than the node having ID 153 in the
counterclockwise direction.
[0151] Method 1100 includes an act of determining that the
destination is not within the receiving node's neighborhood set of
nodes for any of the one or more classes of nodes defined by the
proximity criterion (act 1103). For example, the node having ID 172
can determine that destination 201 is not in a corresponding
neighborhood set in ring 404 or in ring 401.
[0152] Method 1100 includes an act of identifying an intermediate
node from the receiving node's routing table, the intermediate node
being numerically closer to the destination than other routing
nodes in the routing table (act 1104). For example, the node having
ID 172 can identify the node having ID 194 as being numerically
closer to destination 201 than other routing nodes in ring 404. The
method 1100 includes an act of sending the message to the
intermediate node (act 1105). For example, the node having ID 172
can send the received message to the node having ID 194. The node
having ID 172 can send the received message to the node having ID
194 to honor a previously defined partially ordered list of
proximity criterion
[0153] Node 194 may be as close to destination 201 as is possible
within ring 404. Thus, proximity can be relaxed just enough to
enable further routing towards the destination to be made in ring
401 in the next leg. That is, routing is transitioned from ring 404
to ring 401 since no further progress towards the destination can
be made on ring 404. Alternately, it may be that the node having ID
201 is within the neighborhood of the node having ID 194 in ring
401 resulting in no further routing. Thus, in some embodiments,
relaxing proximity criteria to get to the next higher ring is
enough to cause further routing.
[0154] However, in other embodiments, incremental relaxation of
proximity criteria causing transition to the next higher ring
continues until further routing can occur (or until the root ring
is encountered). That is, a plurality of transitions to higher
rings occurs before further routing progress can be made. For
example, referring now to FIG. 5, when no further routing progress
can be made on ring 531, proximity criteria may be relaxed enough
to transition to ring 511 or even to root ring 501.
[0155] FIG. 6 and the following discussion are intended to provide
a brief, general description of a suitable computing environment in
which the invention may be implemented. Although not required, the
invention will be described in the general context of
computer-executable instructions, such as program modules, being
executed by computer systems. Generally, program modules include
routines, programs, objects, components, data structures, and the
like, which perform particular tasks or implement particular
abstract data types. Computer-executable instructions, associated
data structures, and program modules represent examples of the
program code means for executing acts of the methods disclosed
herein.
[0156] With reference to FIG. 6, an example system for implementing
the invention includes a general-purpose computing device in the
form of computer system 620, including a processing unit 621, a
system memory 622, and a system bus 623 that couples various system
components including the system memory 622 to the processing unit
621. Processing unit 621 can execute computer-executable
instructions designed to implement features of computer system 620,
including features of the present invention. The system bus 623 may
be any of several types of bus structures including a memory bus or
memory controller, a peripheral bus, and a local bus using any of a
variety of bus architectures. The system memory includes read only
memory ("ROM") 624 and random access memory ("RAM") 625. A basic
input/output system ("BIOS") 626, containing the basic routines
that help transfer information between elements within computer
system 620, such as during start-up, may be stored in ROM 624.
[0157] The computer system 620 may also include magnetic hard disk
drive 627 for reading from and writing to magnetic hard disk 639,
magnetic disk drive 628 for reading from or writing to removable
magnetic disk 629, and optical disk drive 630 for reading from or
writing to removable optical disk 631, such as, or example, a
CD-ROM or other optical media. The magnetic hard disk drive 627,
magnetic disk drive 628, and optical disk drive 630 are connected
to the system bus 623 by hard disk drive interface 632, magnetic
disk drive-interface 633, and optical drive interface 634,
respectively. The drives and their associated computer-readable
media provide nonvolatile storage of computer-executable
instructions, data structures, program modules, and other data for
the computer system 620. Although the example environment described
herein employs magnetic hard disk 639, removable magnetic disk 629
and removable optical disk 631, other types of computer readable
media for storing data can be used, including magnetic cassettes,
flash memory cards, digital versatile disks, Bernoulli cartridges,
RAMs, ROMs, and the like.
[0158] Program code means comprising one or more program modules
may be stored on hard disk 639, magnetic disk 629, optical disk
631, ROM 624 or RAM 625, including an operating system 635, one or
more application programs 636, other program modules 637, and
program data 638. A user may enter commands and information into
computer system 620 through keyboard 640, pointing device 642, or
other input devices (not shown), such as, for example, a
microphone, joy stick, game pad, scanner, or the like. These and
other input devices can be connected to the processing unit 621
through input/output interface 646 coupled to system bus 623.
Input/output interface 646 logically represents any of a wide
variety of different interfaces, such as, for example, a serial
port interface, a PS/2 interface, a parallel port interface, a
Universal Serial Bus ("USB") interface, or an Institute of
Electrical and Electronics Engineers ("IEEE") 1394 interface (i.e.,
a FireWire interface), or may even logically represent a
combination of different interfaces.
[0159] A monitor 647 or other display device is also connected to
system bus 623 via video interface 648. Speakers 669 or other audio
output device is also connected to system bus 623 via audio
interface 649. Other peripheral output devices (not shown), such
as, for example, printers, can also be connected to computer system
620.
[0160] Computer system 620 is connectable to networks, such as, for
example, an office-wide or enterprise-wide computer network, a home
network, an intranet, and/or the Internet. Computer system 620 can
exchange data with external sources, such as, for example, remote
computer systems, remote applications, and/or remote databases over
such networks.
[0161] Computer system 620 includes network interface 653, through
which computer system 620 receives data from external sources
and/or transmits data to external sources. As depicted in FIG. 6,
network interface 653 facilitates the exchange of data with remote
computer system 683 via link 651. Network interface 653 can
logically represent one or more software and/or hardware modules,
such as, for example, a network interface card and corresponding
Network Driver Interface Specification ("NDIS") stack. Link 651
represents a portion of a network (e.g., an Ethernet segment), and
remote computer system 683 represents a node of the network.
[0162] Likewise, computer system 620 includes input/output
interface 646, through which computer system 620 receives data from
external sources and/or transmits data to external sources.
Input/output interface 646 is coupled to modem 654 (e.g., a
standard modem, a cable modem, or digital subscriber line ("DSL")
modem) via link 659, through which computer system 620 receives
data from and/or transmits data to external sources. As depicted in
FIG. 6, input/output interface 646 and modem 654 facilitate the
exchange of data with remote computer system 693 via link 652. Link
652 represents a portion of a network and remote computer system
693 represents a node of the network.
[0163] While FIG. 6 represents a suitable operating environment for
the present invention, the principles of the present invention may
be employed in any system that is capable of, with suitable
modification if necessary, implementing the principles of the
present invention. The environment illustrated in FIG. 6 is
illustrative only and by no means represents even a small portion
of the wide variety of environments in which the principles of the
present invention may be implemented.
[0164] In accordance with the present invention, nodes, application
layers, and other lower layers, as well as associated data,
including routing tables and node IDs may be stored and accessed
from any of the computer-readable media associated with computer
system 620. For example, portions of such modules and portions of
associated program data may be included in operating system 635,
application programs 636, program modules 637 and/or program data
638, for storage in system memory 622.
[0165] When a mass storage device, such as, for example, magnetic
hard disk 639, is coupled to computer system 620, such modules and
associated program data may also be stored in the mass storage
device. In a networked environment, program modules depicted
relative to computer system 620, or portions thereof, can be stored
in remote memory storage devices, such as, system memory and/or
mass storage devices associated with remote computer system 683
and/or remote computer system 693. Execution of such modules may be
performed in a distributed environment as previously described.
[0166] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrative and not restrictive. The scope of
the invention is, therefore, indicated by the appended claims
rather than by the foregoing description. All changes, which come
within the meaning and range of equivalency of the claims, are to
be embraced within their scope.
* * * * *