Standard interfaces and base classes for JDBC
RowSet
implementations. This package contains interfaces and classes
that a standard
RowSet implementation either implements or extends.
Table of Contents
This package specifies five standard JDBC
RowSet interfaces.
All five extend the
RowSet interface described in the JDBC 3.0
specification. It is anticipated that additional definitions
of more specialized JDBC
RowSet types will emerge as this technology
matures. Future definitions
should be specified as subinterfaces using
inheritance similar to the way it is used in this specification.
Note: The interface definitions provided in this package form the basis for
all compliant JDBC RowSet implementations. Vendors and more advanced
developers who intend to provide their own compliant RowSet implementations
should pay particular attention to the assertions detailed in specification
interfaces.
JdbcRowSet - A wrapper around
a ResultSet object that makes it possible to use the result set as a
JavaBeansTM component. Thus,
a JdbcRowSet object can be a Bean that any tool
makes available for assembling an application as part of a component based
architecture . A JdbcRowSet object is a connected RowSet
object, that is, it
must continually maintain its connection to its data source using a JDBC
technology-enabled driver ("JDBC driver"). In addition, a JdbcRowSet
object provides a fully updatable and scrollable tabular
data structure as defined in the JDBC 3.0 specification.
-
CachedRowSetTM>
- A CachedRowSet object is a JavaBeansTM
component that is scrollable, updatable, serializable, and generally disconnected from
the source of its data. A CachedRowSet object
typically contains rows from a result set, but it can also contain rows from any
file with a tabular format, such as a spreadsheet. CachedRowSet implementations
must use the SyncFactory to manage and obtain pluggable
SyncProvider objects to provide synchronization between the
disconnected RowSet object and the originating data source.
Typically a SyncProvider implementation relies upon a JDBC
driver to obtain connectivity to a particular data source.
Further details on this mechanism are discussed in the javax.sql.rowset.spi package
specification.
WebRowSet - A
WebRowSet object is an extension of CachedRowSet
that can read and write a RowSet object in a well formed XML format.
This class calls an XmlReader object
(an extension of the RowSetReader
interface) to read a rowset in XML format. It calls an
XmlWriter object (an extension of the
RowSetWriter interface)
to write a rowset in XML format. The reader and writer required by
WebRowSet objects are provided by the
SyncFactory in the form of SyncProvider
implementations. In order to ensure well formed XML usage, a standard generic XML
Schema is defined and published at
http://java.sun.com/xml/ns/jdbc/webrowset.xsd.
FilteredRowSet - A
FilteredRowSet object provides filtering functionality in a programmatic
and extensible way. There are many instances when a RowSet object
has a need to provide filtering in its contents without sacrificing the disconnected
environment, thus saving the expense of having to create a connection to the data source.
Solutions to this need vary from providing heavyweight full scale
SQL query abilities, to portable components, to more lightweight
approaches. A FilteredRowSet object consumes
an implementation of the Predicate
interface, which may define a filter at run time. In turn, a
FilteredRowSet object is tasked with enforcing the set filter for both
inbound and outbound read and write operations. That is, all filters can be
considered as bi-directional. No standard filters are defined;
however, sufficient mechanics are specified to permit any required filter to be
implemented.
JoinRowSet - The JoinRowSet
interface describes a mechanism by which relationships can be established between
two or more standard RowSet implementations. Any number of RowSet
objects can be added to a JoinRowSet object provided the RowSetobjects
can be related in a SQL JOIN like fashion. By definition, the SQL JOIN
statement is used to combine the data contained in two (or more) relational
database tables based upon a common attribute. By establishing and then enforcing
column matches, a JoinRowSet object establishes relationships between
RowSet instances without the need to touch the originating data source.
Compliant implementations of JDBC
RowSet Implementations
must follow the assertions described in this specification. In accordance
with the terms of the
Java Community Process, a
Test Compatibility Kit (TCK) can be licensed to ensure compatibility with the
specification. The following paragraphs outline a number of starting points for
implementers of the standard JDBC
RowSet definitions. Implementers
should also consult the
Implementer's Guide in the
javax.sql.rowset.spi package for guidelines
on
SyncProvider implementations.
- 3.1 Role of the
BaseRowSet Class
A compliant JDBC RowSet implementation must implement one or more
standard interfaces specified in this package and and may extend the
BaseRowSet abstract class. For example, a
CachedRowSet implementation must implement the CachedRowSet
interface and extend the BaseRowSet abstract class. The
BaseRowSet class provides the standard architecture on which all
RowSet implementations should be built, regardless of whether the
RowSet objects exist in a connected or disconnected environment.
The BaseRowSet abstract class provides any RowSet implementation
with its base functionality, including property manipulation and event notification
that is fully compliant with JavaBeans
component requirements. As an example, all implementations provided in the
reference implementations (contained in the com.sun.rowset package) use
the BaseRowSet class as a basis for their implementations.
The following table illustrates the features that the BaseRowSet
abstract class provides.
Feature
|
Details
|
Properties
|
Provides standard JavaBeans property manipulation
mechanisms to allow applications to get and set RowSet command and
property values. Refer to the documentation of the javax.sql.RowSet
interface (available in the JDBC 3.0 specification) for more details on
the standard RowSet properties.
|
Event notification
|
Provides standard JavaBeans event notifications
to registered event listeners. Refer to the documentation of javax.sql.RowSetEvent
interface (available in the JDBC 3.0 specification) for
more details on how to register and handle standard RowSet events generated
by compliant implementations.
|
Setters for a RowSet object's command
|
Provides a complete set of setter methods
for setting RowSet command parameters.
|
Streams
|
Provides fields for storing of stream instances
in addition to providing a set of constants for stream type designation.
|
- 3.2 Connected RowSet Requirements
The JdbcRowSet describes a RowSet object that must always
be connected to the originating data source. Implementations of the JdbcRowSet
should ensure that this connection is provided solely by a JDBC driver.
Furthermore, RowSet objects that are implementations of the
JdbcRowSet interface and are therefore operating in a connected environment
do not use the SyncFactory to obtain a RowSetReader object
or a RowSetWriter object. They can safely rely on the JDBC driver to
supply their needs by virtue of the presence of an underlying updatable and scrollable
ResultSet implementation.
-
3.3 Disconnected RowSet Requirements
A disconnected RowSet object, such as a CachedRowSet object,
should delegate
connection management to a SyncProvider object provided by the
SyncFactory. To ensure fully disconnected semantics, all
disconnected RowSet objects must ensure
that the original connection made to the data source to populate the RowSet
object is closed to permit the garbage collector to recover and release resources. The
SyncProvider object ensures that the critical JDBC properties are
maintained in order to re-establish a connection to the data source when a
synchronization is required. A disconnected RowSet object should
therefore ensure that no
extraneous references remain on the Connection object.
- 3.4 Role of RowSetMetaDataImpl
The RowsetMetaDataImpl class is a utility class that provides an implementation of the
RowSetMetaData interface, supplying standard setter
method implementations for metadata for both connected and disconnected
RowSet objects. All implementations are free to use this standard
implementation but are not required to do so.
- 3.5 RowSetWarning Class
The RowSetWarning class provides warnings that can be set
on RowSet implementations.
Similar to SQLWarning objects,
RowSetWarning objects are silently chained to the object whose method
caused the warning to be thrown. All RowSet implementations should
ensure that this chaining occurs if a warning is generated and also ensure that the
warnings are available via the getRowSetWarnings method defined in either
the JdbcRowSet interface or the CachedRowSet interface.
After a warning has been retrieved with one of the
getRowSetWarnings methods, the RowSetWarning method
getNextWarning can be called on it to retrieve any warnings that might
be chained on it. If a warning is returned, getNextWarning can be called
on it, and so on until there are no more warnings.
- 3.6 The Joinable Interface
The Joinable interface provides both connected and disconnected
RowSet objects with the capability to be added to a
JoinRowSet object in an SQL JOIN operation.
A RowSet object that has implemented the Joinable
interface can set a match column, retrieve a match column, or unset a match column.
A JoinRowSet object can then use the RowSet object's
match column as a basis for adding the RowSet object.
Direct link to this page
Package: javax.sql.rowset
Standard interfaces and base classes for JDBC 
BaseRowSet
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CachedRowSet
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RowSetMetaDataImpl
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RowSetWarning
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