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431 lines
17 KiB
431 lines
17 KiB
/*
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* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*/
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package javax.sql.rowset.spi;
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import javax.sql.*;
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/**
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* The synchronization mechanism that provides reader/writer capabilities for
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* disconnected <code>RowSet</code> objects.
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* A <code>SyncProvider</code> implementation is a class that extends the
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* <code>SyncProvider</code> abstract class.
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* <P>
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* A <code>SyncProvider</code> implementation is
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* identified by a unique ID, which is its fully qualified class name.
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* This name must be registered with the
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* <code>SyncFactory</code> SPI, thus making the implementation available to
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* all <code>RowSet</code> implementations.
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* The factory mechanism in the reference implementation uses this name to instantiate
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* the implementation, which can then provide a <code>RowSet</code> object with its
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* reader (a <code>javax.sql.RowSetReader</code> object) and its writer (a
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* <code>javax.sql.RowSetWriter</code> object).
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* <P>
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* The Jdbc <code>RowSet</code> Implementations specification provides two
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* reference implementations of the <code>SyncProvider</code> abstract class:
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* <code>RIOptimisticProvider</code> and <code>RIXMLProvider</code>.
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* The <code>RIOptimisticProvider</code> can set any <code>RowSet</code>
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* implementation with a <code>RowSetReader</code> object and a
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* <code>RowSetWriter</code> object. However, only the <code>RIXMLProvider</code>
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* implementation can set an <code>XmlReader</code> object and an
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* <code>XmlWriter</code> object. A <code>WebRowSet</code> object uses the
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* <code>XmlReader</code> object to read data in XML format to populate itself with that
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* data. It uses the <code>XmlWriter</code> object to write itself to a stream or
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* <code>java.io.Writer</code> object in XML format.
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*
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* <h3>1.0 Naming Convention for Implementations</h3>
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* As a guide to naming <code>SyncProvider</code>
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* implementations, the following should be noted:
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* <UL>
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* <li>The name for a <code>SyncProvider</code> implementation
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* is its fully qualified class name.
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* <li>It is recommended that vendors supply a
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* <code>SyncProvider</code> implementation in a package named <code>providers</code>.
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* </UL>
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* <p>
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* For instance, if a vendor named Fred, Inc. offered a
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* <code>SyncProvider</code> implementation, you could have the following:
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* <PRE>
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* Vendor name: Fred, Inc.
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* Domain name of vendor: com.fred
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* Package name: com.fred.providers
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* SyncProvider implementation class name: HighAvailabilityProvider
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*
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* Fully qualified class name of SyncProvider implementation:
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* com.fred.providers.HighAvailabilityProvider
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* </PRE>
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* <P>
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* The following line of code uses the fully qualified name to register
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* this implementation with the <code>SyncFactory</code> static instance.
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* <PRE>
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* SyncFactory.registerProvider(
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* "com.fred.providers.HighAvailabilityProvider");
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* </PRE>
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* <P>
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* The default <code>SyncProvider</code> object provided with the reference
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* implementation uses the following name:
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* <pre>
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* com.sun.rowset.providers.RIOptimisticProvider
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* </pre>
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* <p>
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* A vendor can register a <code>SyncProvider</code> implementation class name
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* with Oracle Corporation by sending email to jdbc@sun.com.
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* Oracle will maintain a database listing the
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* available <code>SyncProvider</code> implementations for use with compliant
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* <code>RowSet</code> implementations. This database will be similar to the
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* one already maintained to list available JDBC drivers.
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* <P>
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* Vendors should refer to the reference implementation synchronization
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* providers for additional guidance on how to implement a new
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* <code>SyncProvider</code> implementation.
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*
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* <h3>2.0 How a <code>RowSet</code> Object Gets Its Provider</h3>
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*
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* A disconnected <code>Rowset</code> object may get access to a
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* <code>SyncProvider</code> object in one of the following two ways:
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* <UL>
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* <LI>Using a constructor<BR>
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* <PRE>
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* CachedRowSet crs = new CachedRowSet(
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* "com.fred.providers.HighAvailabilitySyncProvider");
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* </PRE>
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* <LI>Using the <code>setSyncProvider</code> method
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* <PRE>
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* CachedRowSet crs = new CachedRowSet();
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* crs.setSyncProvider("com.fred.providers.HighAvailabilitySyncProvider");
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* </PRE>
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* </UL>
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* <p>
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* By default, the reference implementations of the <code>RowSet</code> synchronization
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* providers are always available to the Java platform.
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* If no other pluggable synchronization providers have been correctly
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* registered, the <code>SyncFactory</code> will automatically generate
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* an instance of the default <code>SyncProvider</code> reference implementation.
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* Thus, in the preceding code fragment, if no implementation named
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* <code>com.fred.providers.HighAvailabilitySyncProvider</code> has been
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* registered with the <code>SyncFactory</code> instance, <i>crs</i> will be
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* assigned the default provider in the reference implementation, which is
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* <code>com.sun.rowset.providers.RIOptimisticProvider</code>.
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*
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* <h3>3.0 Violations and Synchronization Issues</h3>
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* If an update between a disconnected <code>RowSet</code> object
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* and a data source violates
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* the original query or the underlying data source constraints, this will
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* result in undefined behavior for all disconnected <code>RowSet</code> implementations
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* and their designated <code>SyncProvider</code> implementations.
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* Not defining the behavior when such violations occur offers greater flexibility
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* for a <code>SyncProvider</code>
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* implementation to determine its own best course of action.
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* <p>
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* A <code>SyncProvider</code> implementation
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* may choose to implement a specific handler to
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* handle a subset of query violations.
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* However if an original query violation or a more general data source constraint
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* violation is not handled by the <code>SyncProvider</code> implementation,
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* all <code>SyncProvider</code>
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* objects must throw a <code>SyncProviderException</code>.
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*
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* <h3>4.0 Updatable SQL VIEWs</h3>
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* It is possible for any disconnected or connected <code>RowSet</code> object to be populated
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* from an SQL query that is formulated originally from an SQL <code>VIEW</code>.
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* While in many cases it is possible for an update to be performed to an
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* underlying view, such an update requires additional metadata, which may vary.
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* The <code>SyncProvider</code> class provides two constants to indicate whether
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* an implementation supports updating an SQL <code>VIEW</code>.
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* <ul>
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* <li><code><b>NONUPDATABLE_VIEW_SYNC</b></code> - Indicates that a <code>SyncProvider</code>
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* implementation does not support synchronization with an SQL <code>VIEW</code> as the
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* underlying source of data for the <code>RowSet</code> object.
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* <li><code><b>UPDATABLE_VIEW_SYNC</b></code> - Indicates that a
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* <code>SyncProvider</code> implementation
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* supports synchronization with an SQL <code>VIEW</code> as the underlying source
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* of data.
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* </ul>
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* <P>
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* The default is for a <code>RowSet</code> object not to be updatable if it was
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* populated with data from an SQL <code>VIEW</code>.
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*
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* <h3>5.0 <code>SyncProvider</code> Constants</h3>
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* The <code>SyncProvider</code> class provides three sets of constants that
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* are used as return values or parameters for <code>SyncProvider</code> methods.
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* <code>SyncProvider</code> objects may be implemented to perform synchronization
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* between a <code>RowSet</code> object and its underlying data source with varying
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* degrees of of care. The first group of constants indicate how synchronization
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* is handled. For example, <code>GRADE_NONE</code> indicates that a
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* <code>SyncProvider</code> object will not take any care to see what data is
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* valid and will simply write the <code>RowSet</code> data to the data source.
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* <code>GRADE_MODIFIED_AT_COMMIT</code> indicates that the provider will check
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* only modified data for validity. Other grades check all data for validity
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* or set locks when data is modified or loaded.
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* <OL>
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* <LI>Constants to indicate the synchronization grade of a
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* <code>SyncProvider</code> object
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* <UL>
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* <LI>SyncProvider.GRADE_NONE
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* <LI>SyncProvider.GRADE_MODIFIED_AT_COMMIT
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* <LI>SyncProvider.GRADE_CHECK_ALL_AT_COMMIT
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* <LI>SyncProvider.GRADE_LOCK_WHEN_MODIFIED
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* <LI>SyncProvider.GRADE_LOCK_WHEN_LOADED
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* </UL>
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* <LI>Constants to indicate what locks are set on the data source
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* <UL>
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* <LI>SyncProvider.DATASOURCE_NO_LOCK
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* <LI>SyncProvider.DATASOURCE_ROW_LOCK
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* <LI>SyncProvider.DATASOURCE_TABLE_LOCK
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* <LI>SyncProvider.DATASOURCE_DB_LOCK
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* </UL>
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* <LI>Constants to indicate whether a <code>SyncProvider</code> object can
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* perform updates to an SQL <code>VIEW</code> <BR>
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* These constants are explained in the preceding section (4.0).
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* <UL>
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* <LI>SyncProvider.UPDATABLE_VIEW_SYNC
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* <LI>SyncProvider.NONUPDATABLE_VIEW_SYNC
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* </UL>
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* </OL>
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*
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* @author Jonathan Bruce
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* @see javax.sql.rowset.spi.SyncFactory
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* @see javax.sql.rowset.spi.SyncFactoryException
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*/
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public abstract class SyncProvider {
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/**
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* Creates a default <code>SyncProvider</code> object.
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*/
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public SyncProvider() {
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}
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/**
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* Returns the unique identifier for this <code>SyncProvider</code> object.
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*
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* @return a <code>String</code> object with the fully qualified class name of
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* this <code>SyncProvider</code> object
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*/
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public abstract String getProviderID();
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/**
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* Returns a <code>javax.sql.RowSetReader</code> object, which can be used to
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* populate a <code>RowSet</code> object with data.
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*
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* @return a <code>javax.sql.RowSetReader</code> object
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*/
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public abstract RowSetReader getRowSetReader();
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/**
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* Returns a <code>javax.sql.RowSetWriter</code> object, which can be
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* used to write a <code>RowSet</code> object's data back to the
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* underlying data source.
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*
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* @return a <code>javax.sql.RowSetWriter</code> object
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*/
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public abstract RowSetWriter getRowSetWriter();
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/**
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* Returns a constant indicating the
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* grade of synchronization a <code>RowSet</code> object can expect from
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* this <code>SyncProvider</code> object.
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*
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* @return an int that is one of the following constants:
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* SyncProvider.GRADE_NONE,
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* SyncProvider.GRADE_CHECK_MODIFIED_AT_COMMIT,
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* SyncProvider.GRADE_CHECK_ALL_AT_COMMIT,
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* SyncProvider.GRADE_LOCK_WHEN_MODIFIED,
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* SyncProvider.GRADE_LOCK_WHEN_LOADED
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*/
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public abstract int getProviderGrade();
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/**
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* Sets a lock on the underlying data source at the level indicated by
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* <i>datasource_lock</i>. This should cause the
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* <code>SyncProvider</code> to adjust its behavior by increasing or
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* decreasing the level of optimism it provides for a successful
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* synchronization.
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*
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* @param datasource_lock one of the following constants indicating the severity
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* level of data source lock required:
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* <pre>
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* SyncProvider.DATASOURCE_NO_LOCK,
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* SyncProvider.DATASOURCE_ROW_LOCK,
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* SyncProvider.DATASOURCE_TABLE_LOCK,
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* SyncProvider.DATASOURCE_DB_LOCK,
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* </pre>
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* @throws SyncProviderException if an unsupported data source locking level
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* is set.
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* @see #getDataSourceLock
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*/
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public abstract void setDataSourceLock(int datasource_lock)
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throws SyncProviderException;
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/**
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* Returns the current data source lock severity level active in this
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* <code>SyncProvider</code> implementation.
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*
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* @return a constant indicating the current level of data source lock
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* active in this <code>SyncProvider</code> object;
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* one of the following:
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* <pre>
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* SyncProvider.DATASOURCE_NO_LOCK,
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* SyncProvider.DATASOURCE_ROW_LOCK,
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* SyncProvider.DATASOURCE_TABLE_LOCK,
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* SyncProvider.DATASOURCE_DB_LOCK
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* </pre>
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* @throws SyncProviderException if an error occurs determining the data
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* source locking level.
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* @see #setDataSourceLock
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*/
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public abstract int getDataSourceLock()
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throws SyncProviderException;
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/**
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* Returns whether this <code>SyncProvider</code> implementation
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* can perform synchronization between a <code>RowSet</code> object
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* and the SQL <code>VIEW</code> in the data source from which
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* the <code>RowSet</code> object got its data.
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*
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* @return an <code>int</code> saying whether this <code>SyncProvider</code>
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* object supports updating an SQL <code>VIEW</code>; one of the
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* following:
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* SyncProvider.UPDATABLE_VIEW_SYNC,
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* SyncProvider.NONUPDATABLE_VIEW_SYNC
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*/
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public abstract int supportsUpdatableView();
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/**
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* Returns the release version of this <code>SyncProvider</code> instance.
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*
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* @return a <code>String</code> detailing the release version of the
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* <code>SyncProvider</code> implementation
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*/
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public abstract String getVersion();
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/**
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* Returns the vendor name of this <code>SyncProvider</code> instance
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*
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* @return a <code>String</code> detailing the vendor name of this
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* <code>SyncProvider</code> implementation
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*/
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public abstract String getVendor();
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/*
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* Standard description of synchronization grades that a SyncProvider
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* could provide.
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*/
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/**
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* Indicates that no synchronization with the originating data source is
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* provided. A <code>SyncProvider</code>
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* implementation returning this grade will simply attempt to write
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* updates in the <code>RowSet</code> object to the underlying data
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* source without checking the validity of any data.
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*
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*/
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public static final int GRADE_NONE = 1;
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/**
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* Indicates a low level optimistic synchronization grade with
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* respect to the originating data source.
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*
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* A <code>SyncProvider</code> implementation
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* returning this grade will check only rows that have changed.
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*
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*/
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public static final int GRADE_CHECK_MODIFIED_AT_COMMIT = 2;
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/**
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* Indicates a high level optimistic synchronization grade with
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* respect to the originating data source.
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*
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* A <code>SyncProvider</code> implementation
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* returning this grade will check all rows, including rows that have not
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* changed.
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*/
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public static final int GRADE_CHECK_ALL_AT_COMMIT = 3;
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/**
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* Indicates a pessimistic synchronization grade with
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* respect to the originating data source.
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*
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* A <code>SyncProvider</code>
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* implementation returning this grade will lock the row in the originating
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* data source.
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*/
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public static final int GRADE_LOCK_WHEN_MODIFIED = 4;
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/**
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* Indicates the most pessimistic synchronization grade with
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* respect to the originating
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* data source. A <code>SyncProvider</code>
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* implementation returning this grade will lock the entire view and/or
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* table affected by the original statement used to populate a
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* <code>RowSet</code> object.
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*/
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public static final int GRADE_LOCK_WHEN_LOADED = 5;
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/**
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* Indicates that no locks remain on the originating data source. This is the default
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* lock setting for all <code>SyncProvider</code> implementations unless
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* otherwise directed by a <code>RowSet</code> object.
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*/
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public static final int DATASOURCE_NO_LOCK = 1;
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/**
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* Indicates that a lock is placed on the rows that are touched by the original
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* SQL statement used to populate the <code>RowSet</code> object
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* that is using this <code>SyncProvider</code> object.
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*/
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public static final int DATASOURCE_ROW_LOCK = 2;
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/**
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* Indicates that a lock is placed on all tables that are touched by the original
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* SQL statement used to populate the <code>RowSet</code> object
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* that is using this <code>SyncProvider</code> object.
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*/
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public static final int DATASOURCE_TABLE_LOCK = 3;
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/**
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* Indicates that a lock is placed on the entire data source that is the source of
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* data for the <code>RowSet</code> object
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* that is using this <code>SyncProvider</code> object.
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*/
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public static final int DATASOURCE_DB_LOCK = 4;
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/**
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* Indicates that a <code>SyncProvider</code> implementation
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* supports synchronization between a <code>RowSet</code> object and
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* the SQL <code>VIEW</code> used to populate it.
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*/
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public static final int UPDATABLE_VIEW_SYNC = 5;
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/**
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* Indicates that a <code>SyncProvider</code> implementation
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* does <B>not</B> support synchronization between a <code>RowSet</code>
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* object and the SQL <code>VIEW</code> used to populate it.
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*/
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public static final int NONUPDATABLE_VIEW_SYNC = 6;
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}
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