U.S. patent application number 10/341107 was filed with the patent office on 2003-08-28 for systems and methods for dynamic querying.
Invention is credited to Shinn, Matthew, White, Seth, Woollen, Rob.
Application Number | 20030163460 10/341107 |
Document ID | / |
Family ID | 27616681 |
Filed Date | 2003-08-28 |
United States Patent
Application |
20030163460 |
Kind Code |
A1 |
Shinn, Matthew ; et
al. |
August 28, 2003 |
Systems and methods for dynamic querying
Abstract
A user can generate queries dynamically at runtime without
having to redeploy the appropriate EJB or hard-code the query into
the user application. A properties object can be generated to
accept the query settings from the user. These settings can be
extracted at runtime when the appropriate finder method is invoked,
such that the desired query statement, such as a SQL statement, can
be generated and executed against the database. This description is
not intended to be a complete description of, or limit the scope
of, the invention. Other features, aspects, and objects of the
invention can be obtained from a review of the specification, the
figures, and the claims.
Inventors: |
Shinn, Matthew; (San
Francisco, CA) ; White, Seth; (San Francisco, CA)
; Woollen, Rob; (San Francisco, CA) |
Correspondence
Address: |
Sheldon R. Meyer
FLIESLER DUBB MEYER & LOVEJOY LLP
Fourth Floor
Four Embarcadero Center
San Francisco
CA
94111-4156
US
|
Family ID: |
27616681 |
Appl. No.: |
10/341107 |
Filed: |
January 13, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60349432 |
Jan 18, 2002 |
|
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Current U.S.
Class: |
1/1 ;
707/999.003; 707/E17.005 |
Current CPC
Class: |
Y10S 707/99933 20130101;
Y10S 707/99944 20130101; G06F 16/24 20190101 |
Class at
Publication: |
707/3 |
International
Class: |
G06F 007/00 |
Claims
What is claimed is:
1. A system for dynamically generating a query to be executed on a
database, comprising: a properties object adapted to contain
settings for a query as specified by a user; a finder method for
initiating the query; and a server capable of querying the
database, the server capable of receiving a call from the finder
method and reading the settings from the properties object in order
to generate the appropriate SQL query statements to be sent to the
database.
2. A system according to claim 1, further comprising: a user
interface adapted to allow a user to specify the settings in the
property object.
3. A system according to claim 1, further comprising: a client
containing the properties object and the finder method.
4. A system according to claim 1, further comprising: a bean
associated with the database upon which the finder method can be
invoked.
5. A system according to claim 1, further comprising: an element in
a deployment descriptor for enabling dynamic querying.
6. A method for dynamically generating a query to be executed
against a database, comprising: generating a properties object
containing settings for a query; invoking a finder method;
extracting the settings from the properties object and parsing the
finder method in order to generate a query statement; and executing
the query statement on the database.
7. A method according to claim 6, wherein: generating a properties
object occurs at runtime.
8. A method according to claim 6, wherein: extracting the settings
from the properties object and parsing the finder method in order
to generate a SQL query statement occurs at runtime.
9. A method according to claim 6, further comprising: enabling
dynamic querying by setting an element in a deployment
descriptor.
10. A method according to claim 6, further comprising: allowing the
user to specify the settings for the query at runtime.
11. A method for generating dynamic queries, comprising: specifying
settings to be used in generating the query using a user interface;
generating a properties object to hold the settings; invoking a
finder method; and parsing the finder method and reading the
settings from the property object in order to generate the
query.
12. A system for generating dynamic queries, comprising: means for
generating a properties object to hold settings to be used in
generating a query; means for invoking a finder method; and means
for parsing the finder method and reading the settings from the
property object in order to generate the query.
13. A computer-readable medium, comprising: means for generating a
properties object to hold settings to be used in generating a
query; means for invoking a finder method; and means for parsing
the finder method and reading the settings from the property object
in order to generate the query.
14. A computer program product for execution by a server computer
for generating dynamic queries, comprising: computer code for
generating a properties object to hold settings to be used in
generating a query; computer code for invoking a finder method; and
computer code for parsing the finder method and reading the
settings from the property object in order to generate the
query.
15. A computer system comprising: a processor; object code executed
by said processor, said object code configured to: generate a
properties object to hold settings to be used in generating a
query; invoke a finder method; and parse the finder method and
reading the settings from the property object in order to generate
the query.
16. A computer data signal embodied in a transmission medium,
comprising: a code segment including instructions to generate a
properties object to hold settings to be used in generating a
query; a code segment including instructions to invoke a finder
method; and a code segment including instructions to parse the
finder method and reading the settings from the property object in
order to generate the query.
Description
CLAIM OF PRIORITY
[0001] This application claims priority to U.S. Provisional Patent
Application No. 60/349,432, filed Jan. 18, 2002, entitled "SYSTEMS
AND METHODS FOR DYNAMIC QUERYING," which is hereby incorporated
herein by reference.
COPYRIGHT NOTICE
[0002] A portion of the disclosure of this patent document contains
material which is subject to copyright protection. The copyright
owner has no objection to the facsimile reproduction by anyone of
the patent document of the patent disclosure, as it appears in the
Patent and Trademark Office patent file or records, but otherwise
reserves all copyright rights whatsoever.
FIELD OF THE INVENTION
[0003] The present invention relates to executing queries against a
database.
BACKGROUND
[0004] The Enterprise JavaBean (EJB) specification, published by
Sun Microsystems, Inc. of Palo Alto, Calif., describes ways in
which a user can execute queries against a database, as well as
ways in which a user can communicate queries to an EJB container.
Presently, the EJB 2.0 specification forces users to hard-code
finder queries into a deployment descriptor for an EJB. A user
develops a query before deploying the EJB. Once the EJB is
deployed, the user is able to execute the query. A problem exists
with this approach, however, in that it is necessary to redeploy
the EJB every time the user wishes to run a new query.
BRIEF SUMMARY
[0005] Systems and methods in accordance with one embodiment of the
present invention can allow a user to dynamically generate a query
to be executed against a database. A properties object can be
generated that holds settings for the query, which can be specified
by a user at runtime. When the query is to be executed, the user or
application can invoke an appropriate finder method. The server
receiving the call from the finder method can extract the
user-specified settings from the properties object and parse the
finder method in order to generate a query statement. The server
can then execute the query statement on the database and return the
appropriate results. The generating of the properties object and
the query statement can happen at runtime.
[0006] Other features, aspects, and objects of the invention can be
obtained from a review of the specification, the figures, and the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a diagram of a system in accordance with one
embodiment of the present invention.
[0008] FIG. 2 is a flowchart showing the steps of a method that can
be used with the system of FIG. 1.
DETAILED DESCRIPTION
[0009] Systems and methods in accordance with one embodiment of the
present invention can allow a user to define a query
programmatically rather than defining the query statically. Static
queries are defined, for example, by hard-coding the static query
into the deployment descriptor for an EJB. Programmatic queries, or
"dynamic queries", allow users to construct and execute queries in
their application code. This can provide several benefits over
static queries which utilize static finder methods.
[0010] One such benefit is the ability to create and execute new
queries without having to update and redeploy an EJB. When
deploying an EJB with static queries, each query is read and parsed
in order to generate the SQL to be sent to the database. Finder
methods can be utilized in executing the query, which can be
defined in the home interface of an entity bean. An example of a
finder method is findByPrimaryKey( ), which can accept an instance
of a primary key and return an instance of that entity type (or
throw an exception). Additional finder methods can be defined in
local home or remote home interfaces, with each finder method being
associated with a query in the deployment descriptor. With dynamic
queries, however, the query and corresponding SQL can be generated
at runtime.
[0011] Another benefit is that the size of an EJB deployment
descriptor is reduced. Since the finder queries can be created
dynamically, they do not have to be statically defined in the
deployment descriptor. For some applications this approach may be a
little slower, but the added flexibility will outweigh the slight
hit in performance for many users.
[0012] One system and method for implementing dynamic queries
utilizes the generation of a class such as an ejbHome class. Such a
class can be used to implement an extra interface with a method
that can execute the query. As shown in FIG. 1, when a user 100
wants to execute a query against a database 112 at runtime, an
object such as a Java properties object 104 can be generated that
can be populated with the settings for the finder method 106, such
as a container-managed or bean-managed finder method. The finder
method 106 can then be invoked on the query home of the appropriate
EJB 108, which can be stored on a server 110 or EJB container in
communication with, and capable of executing SQL queries against, a
database 112. Once the call makes it into the server 110, the
properties object 104 can be inspected and the user settings
extracted. The finder method 106 can be parsed and the SQL query
statement generated that is to be sent to the database 112. The
query is executed and, depending on the user settings, the use of
the results can be determined. One possible result of such a query
is a collection of EJBs. Another possible result is a number of
values or fields on certain EJBs that match the query.
[0013] A method that can be used in accordance with the system of
FIG. 1 is shown in the flowchart of FIG. 2. In the method, a
properties object is generated that contains user-specified
settings for the query or the finder method, as can be implemented
through a user interface of an ejbHome class 200. The appropriate
finder method is invoked when the user or application wishes to
execute the query 202. The settings are extracted from the
properties object and the finder method is parsed in order to
generate the appropriate SQL query statement, although other
database or data source querying language statements may be
generated by the method 204. The SQL query statement is then
executed against the database 206.
[0014] One embodiment can be implemented through a simple API. To
enable the use of dynamic queries, users can add an element to
their deployment descriptor, such as:
[0015] <!ELEMENT enable-dynamic-queries (#PCDATA)>
[0016] The enable-dynamic-queries element can be a sub-element of a
descriptor such as entity-descriptor. The value of
enable-dynamic-queries can be either "true" or "false" in this
embodiment. Invoking a dynamic query when dynamic queries have not
been enabled can result in an exception being thrown, such as
java.rmi. AccessException or javax.ejb.AccessLocalException,
depending on whether it was invoked from a Remote or Local
interface.
[0017] A generated implementation class, such as HomeImpl that can
be used for all EJB 2.0 Container-Managed Persistence (CMP) beans,
can implement a new interface such as QueryHome. A QueryHome
interface can declare a single method, such as:
1 public Object executeQuery(String query, Properties props) throws
FinderException, RemoteException;
[0018] There can also be a local version of QueryHome which may be
referred to as QueryLocalHome. The only difference between the
interfaces can be the "throws" clause of the executeQuery method.
The QueryLocalHome iinterface can declare a single method:
2 public Object executeQuery(String query, Properties props) throws
FinderException, EJBException;
[0019] The application code can make use of this interface as
follows:
3 InitialContext ic = new InitialContext(); FooHome fh =
(FooHome)ic.lookup("fooHome")` QueryHome qh = (QueryHome)fh; String
query = "SELECT OBJECT(e) FROM EmployeeBean e WHERE e.name = `rob`
"; Properties props = new Properties();
props.setProperty(DynamicQuery.MAX_ELEMENTS, "10"); Collection
results = (Collection)qh.executeQuery(query, props);
[0020] All options that can currently be specified for a static
finder can be set in a Properties object passed to the executeQuery
method. The Properties key for all valid options can be defined in
a DynamicQuery interface. A list of some valid entries is as
follows:
4 Property: Value: Description: GROUP_NAME String The name of the
field-group whose fields are to be loaded into the cache upon
execution of the query. Note that in order for this to work, a
finders- load-bean or equivalent option may need to be enabled for
the EJB. MAX_ELEMENTS int The max-elements attribute is used to
specify the maximum number of elements that should be returned by a
multi-valued query. This option can be similar to the maxRows
feature of JDBC. INCLUDE_UPDATES boolean The include-updates tag is
used to specify that updates made during the current transaction
must be reflected in the result of a query. SQL_SELECT_DISTINCT
boolean Used to control whether the generated SQL `SELECT` will
contain a `DISTINCT` qualifier. Use of the DISTINCT qualifier will
cause the RDBMS to return unique rows. RETURN_TYPE String Indicates
the return type of the executeQuery method. Legal values include
Collection, CursoredCollection, and ResultSet. The default value is
java.util.Collection. NEW_TRANSACTION boolean Indicates whether a
new transaction should be started for the execution of the
DynamicQuery ISOLATION_LEVEL String Indicates the isolation level
to be used if a new transaction is started RESULT_TYPE_MAPPING
String Indicates whether EJBObjects or EJBLocalObjects should be
returned. The legal values are Local and Remote. If the query was
executed on QueryHome, EJBObjects will always be returned. If the
query was executed on QueryLocalHome, EJBLocalObjects will be
returned by default. A result-type-mapping of Remote can be
specified in this case if EJBObjects are desired.
[0021] Ideally, dynamic queries execute nearly as fast as static
queries. Dynamic queries can invariably be somewhat slower since
the queries can require parsing at runtime, whereas static queries
are parsed during deployment. The speed of dynamic queries can be
increased, such as by extending them to take query parameters and
caching the parsed query String.
[0022] The foregoing description of preferred embodiments of the
present invention has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise forms disclosed. Many
modifications and variations will be apparent to one of ordinary
skill in the relevant arts. The embodiments were chosen and
described in order to best explain the principles of the invention
and its practical application, thereby enabling others skilled in
the art to understand the invention for various embodiments and
with various modifications that are suited to the particular use
contemplated. It is intended that the scope of the invention be
defined by the claims and their equivalence.
* * * * *