Class SyncProvider
- java.lang.Object
-
- javax.sql.rowset.spi.SyncProvider
public abstract class SyncProvider extends Object
The synchronization mechanism that provides reader/writer capabilities for disconnected RowSet
objects. A SyncProvider
implementation is a class that extends the SyncProvider
abstract class.
A SyncProvider
implementation is identified by a unique ID, which is its fully qualified class name. This name must be registered with the SyncFactory
SPI, thus making the implementation available to all RowSet
implementations. The factory mechanism in the reference implementation uses this name to instantiate the implementation, which can then provide a RowSet
object with its reader (a javax.sql.RowSetReader
object) and its writer (a javax.sql.RowSetWriter
object).
The Jdbc RowSet
Implementations specification provides two reference implementations of the SyncProvider
abstract class: RIOptimisticProvider
and RIXMLProvider
. The RIOptimisticProvider
can set any RowSet
implementation with a RowSetReader
object and a RowSetWriter
object. However, only the RIXMLProvider
implementation can set an XmlReader
object and an XmlWriter
object. A WebRowSet
object uses the XmlReader
object to read data in XML format to populate itself with that data. It uses the XmlWriter
object to write itself to a stream or java.io.Writer
object in XML format.
1.0 Naming Convention for Implementations
As a guide to namingSyncProvider
implementations, the following should be noted: - The name for a
SyncProvider
implementation is its fully qualified class name. - It is recommended that vendors supply a
SyncProvider
implementation in a package namedproviders
.
For instance, if a vendor named Fred, Inc. offered a SyncProvider
implementation, you could have the following:
Vendor name: Fred, Inc. Domain name of vendor: com.fred Package name: com.fred.providers SyncProvider implementation class name: HighAvailabilityProvider Fully qualified class name of SyncProvider implementation: com.fred.providers.HighAvailabilityProvider
The following line of code uses the fully qualified name to register this implementation with the SyncFactory
static instance.
SyncFactory.registerProvider( "com.fred.providers.HighAvailabilityProvider");
The default SyncProvider
object provided with the reference implementation uses the following name:
com.sun.rowset.providers.RIOptimisticProvider
A vendor can register a SyncProvider
implementation class name with Oracle Corporation by sending email to [email protected]. Oracle will maintain a database listing the available SyncProvider
implementations for use with compliant RowSet
implementations. This database will be similar to the one already maintained to list available JDBC drivers.
Vendors should refer to the reference implementation synchronization providers for additional guidance on how to implement a new SyncProvider
implementation.
2.0 How a RowSet
Object Gets Its Provider
A disconnected Rowset
object may get access to a SyncProvider
object in one of the following two ways: - Using a constructor
CachedRowSet crs = new CachedRowSet( "com.fred.providers.HighAvailabilitySyncProvider");
- Using the
setSyncProvider
methodCachedRowSet crs = new CachedRowSet(); crs.setSyncProvider("com.fred.providers.HighAvailabilitySyncProvider");
By default, the reference implementations of the RowSet
synchronization providers are always available to the Java platform. If no other pluggable synchronization providers have been correctly registered, the SyncFactory
will automatically generate an instance of the default SyncProvider
reference implementation. Thus, in the preceding code fragment, if no implementation named com.fred.providers.HighAvailabilitySyncProvider
has been registered with the SyncFactory
instance, crs will be assigned the default provider in the reference implementation, which is com.sun.rowset.providers.RIOptimisticProvider
.
3.0 Violations and Synchronization Issues
If an update between a disconnectedRowSet
object and a data source violates the original query or the underlying data source constraints, this will result in undefined behavior for all disconnected RowSet
implementations and their designated SyncProvider
implementations. Not defining the behavior when such violations occur offers greater flexibility for a SyncProvider
implementation to determine its own best course of action. A SyncProvider
implementation may choose to implement a specific handler to handle a subset of query violations. However if an original query violation or a more general data source constraint violation is not handled by the SyncProvider
implementation, all SyncProvider
objects must throw a SyncProviderException
.
4.0 Updatable SQL VIEWs
It is possible for any disconnected or connectedRowSet
object to be populated from an SQL query that is formulated originally from an SQL VIEW
. While in many cases it is possible for an update to be performed to an underlying view, such an update requires additional metadata, which may vary. The SyncProvider
class provides two constants to indicate whether an implementation supports updating an SQL VIEW
. -
NONUPDATABLE_VIEW_SYNC
- Indicates that aSyncProvider
implementation does not support synchronization with an SQLVIEW
as the underlying source of data for theRowSet
object. -
UPDATABLE_VIEW_SYNC
- Indicates that aSyncProvider
implementation supports synchronization with an SQLVIEW
as the underlying source of data.
The default is for a RowSet
object not to be updatable if it was populated with data from an SQL VIEW
.
5.0 SyncProvider
Constants
The SyncProvider
class provides three sets of constants that are used as return values or parameters for SyncProvider
methods. SyncProvider
objects may be implemented to perform synchronization between a RowSet
object and its underlying data source with varying degrees of care. The first group of constants indicate how synchronization is handled. For example, GRADE_NONE
indicates that a SyncProvider
object will not take any care to see what data is valid and will simply write the RowSet
data to the data source. GRADE_MODIFIED_AT_COMMIT
indicates that the provider will check only modified data for validity. Other grades check all data for validity or set locks when data is modified or loaded. - Constants to indicate the synchronization grade of a
SyncProvider
object- SyncProvider.GRADE_NONE
- SyncProvider.GRADE_MODIFIED_AT_COMMIT
- SyncProvider.GRADE_CHECK_ALL_AT_COMMIT
- SyncProvider.GRADE_LOCK_WHEN_MODIFIED
- SyncProvider.GRADE_LOCK_WHEN_LOADED
- Constants to indicate what locks are set on the data source
- SyncProvider.DATASOURCE_NO_LOCK
- SyncProvider.DATASOURCE_ROW_LOCK
- SyncProvider.DATASOURCE_TABLE_LOCK
- SyncProvider.DATASOURCE_DB_LOCK
- Constants to indicate whether a
SyncProvider
object can perform updates to an SQLVIEW
These constants are explained in the preceding section (4.0).- SyncProvider.UPDATABLE_VIEW_SYNC
- SyncProvider.NONUPDATABLE_VIEW_SYNC
- Since:
- 1.5
- See Also:
-
SyncFactory
,SyncFactoryException
Field Summary
Modifier and Type | Field | Description |
---|---|---|
static int | DATASOURCE_DB_LOCK | Indicates that a lock is placed on the entire data source that is the source of data for the |
static int | DATASOURCE_NO_LOCK | Indicates that no locks remain on the originating data source. |
static int | DATASOURCE_ROW_LOCK | Indicates that a lock is placed on the rows that are touched by the original SQL statement used to populate the |
static int | DATASOURCE_TABLE_LOCK | Indicates that a lock is placed on all tables that are touched by the original SQL statement used to populate the |
static int | GRADE_CHECK_ALL_AT_COMMIT | Indicates a high level optimistic synchronization grade with respect to the originating data source. |
static int | GRADE_CHECK_MODIFIED_AT_COMMIT | Indicates a low level optimistic synchronization grade with respect to the originating data source. |
static int | GRADE_LOCK_WHEN_LOADED | Indicates the most pessimistic synchronization grade with respect to the originating data source. |
static int | GRADE_LOCK_WHEN_MODIFIED | Indicates a pessimistic synchronization grade with respect to the originating data source. |
static int | GRADE_NONE | Indicates that no synchronization with the originating data source is provided. |
static int | NONUPDATABLE_VIEW_SYNC | Indicates that a |
static int | UPDATABLE_VIEW_SYNC | Indicates that a |
Constructor Summary
Constructor | Description |
---|---|
SyncProvider() | Creates a default |
Method Summary
Modifier and Type | Method | Description |
---|---|---|
abstract int | getDataSourceLock() | Returns the current data source lock severity level active in this |
abstract int | getProviderGrade() | Returns a constant indicating the grade of synchronization a |
abstract String | getProviderID() | Returns the unique identifier for this |
abstract RowSetReader | getRowSetReader() | Returns a |
abstract RowSetWriter | getRowSetWriter() | Returns a |
abstract String | getVendor() | Returns the vendor name of this |
abstract String | getVersion() | Returns the release version of this |
abstract void | setDataSourceLock(int datasource_lock) | Sets a lock on the underlying data source at the level indicated by datasource_lock. |
abstract int | supportsUpdatableView() | Returns whether this |
Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Field Detail
GRADE_NONE
public static final int GRADE_NONE
Indicates that no synchronization with the originating data source is provided. A SyncProvider
implementation returning this grade will simply attempt to write updates in the RowSet
object to the underlying data source without checking the validity of any data.
- See Also:
- Constant Field Values
GRADE_CHECK_MODIFIED_AT_COMMIT
public static final int GRADE_CHECK_MODIFIED_AT_COMMIT
Indicates a low level optimistic synchronization grade with respect to the originating data source. A SyncProvider
implementation returning this grade will check only rows that have changed.
- See Also:
- Constant Field Values
GRADE_CHECK_ALL_AT_COMMIT
public static final int GRADE_CHECK_ALL_AT_COMMIT
Indicates a high level optimistic synchronization grade with respect to the originating data source. A SyncProvider
implementation returning this grade will check all rows, including rows that have not changed.
- See Also:
- Constant Field Values
GRADE_LOCK_WHEN_MODIFIED
public static final int GRADE_LOCK_WHEN_MODIFIED
Indicates a pessimistic synchronization grade with respect to the originating data source. A SyncProvider
implementation returning this grade will lock the row in the originating data source.
- See Also:
- Constant Field Values
GRADE_LOCK_WHEN_LOADED
public static final int GRADE_LOCK_WHEN_LOADED
Indicates the most pessimistic synchronization grade with respect to the originating data source. A SyncProvider
implementation returning this grade will lock the entire view and/or table affected by the original statement used to populate a RowSet
object.
- See Also:
- Constant Field Values
DATASOURCE_NO_LOCK
public static final int DATASOURCE_NO_LOCK
Indicates that no locks remain on the originating data source. This is the default lock setting for all SyncProvider
implementations unless otherwise directed by a RowSet
object.
- See Also:
- Constant Field Values
DATASOURCE_ROW_LOCK
public static final int DATASOURCE_ROW_LOCK
Indicates that a lock is placed on the rows that are touched by the original SQL statement used to populate the RowSet
object that is using this SyncProvider
object.
- See Also:
- Constant Field Values
DATASOURCE_TABLE_LOCK
public static final int DATASOURCE_TABLE_LOCK
Indicates that a lock is placed on all tables that are touched by the original SQL statement used to populate the RowSet
object that is using this SyncProvider
object.
- See Also:
- Constant Field Values
DATASOURCE_DB_LOCK
public static final int DATASOURCE_DB_LOCK
Indicates that a lock is placed on the entire data source that is the source of data for the RowSet
object that is using this SyncProvider
object.
- See Also:
- Constant Field Values
UPDATABLE_VIEW_SYNC
public static final int UPDATABLE_VIEW_SYNC
Indicates that a SyncProvider
implementation supports synchronization between a RowSet
object and the SQL VIEW
used to populate it.
- See Also:
- Constant Field Values
NONUPDATABLE_VIEW_SYNC
public static final int NONUPDATABLE_VIEW_SYNC
Indicates that a SyncProvider
implementation does not support synchronization between a RowSet
object and the SQL VIEW
used to populate it.
- See Also:
- Constant Field Values
Constructor Detail
SyncProvider
public SyncProvider()
Creates a default SyncProvider
object.
Method Detail
getProviderID
public abstract String getProviderID()
Returns the unique identifier for this SyncProvider
object.
- Returns:
- a
String
object with the fully qualified class name of thisSyncProvider
object
getRowSetReader
public abstract RowSetReader getRowSetReader()
Returns a javax.sql.RowSetReader
object, which can be used to populate a RowSet
object with data.
- Returns:
- a
javax.sql.RowSetReader
object
getRowSetWriter
public abstract RowSetWriter getRowSetWriter()
Returns a javax.sql.RowSetWriter
object, which can be used to write a RowSet
object's data back to the underlying data source.
- Returns:
- a
javax.sql.RowSetWriter
object
getProviderGrade
public abstract int getProviderGrade()
Returns a constant indicating the grade of synchronization a RowSet
object can expect from this SyncProvider
object.
- Returns:
- an int that is one of the following constants: SyncProvider.GRADE_NONE, SyncProvider.GRADE_CHECK_MODIFIED_AT_COMMIT, SyncProvider.GRADE_CHECK_ALL_AT_COMMIT, SyncProvider.GRADE_LOCK_WHEN_MODIFIED, SyncProvider.GRADE_LOCK_WHEN_LOADED
setDataSourceLock
public abstract void setDataSourceLock(int datasource_lock) throws SyncProviderException
Sets a lock on the underlying data source at the level indicated by datasource_lock. This should cause the SyncProvider
to adjust its behavior by increasing or decreasing the level of optimism it provides for a successful synchronization.
- Parameters:
-
datasource_lock
- one of the following constants indicating the severity level of data source lock required:SyncProvider.DATASOURCE_NO_LOCK, SyncProvider.DATASOURCE_ROW_LOCK, SyncProvider.DATASOURCE_TABLE_LOCK, SyncProvider.DATASOURCE_DB_LOCK,
- Throws:
-
SyncProviderException
- if an unsupported data source locking level is set. - See Also:
getDataSourceLock()
getDataSourceLock
public abstract int getDataSourceLock() throws SyncProviderException
Returns the current data source lock severity level active in this SyncProvider
implementation.
- Returns:
- a constant indicating the current level of data source lock active in this
SyncProvider
object; one of the following:SyncProvider.DATASOURCE_NO_LOCK, SyncProvider.DATASOURCE_ROW_LOCK, SyncProvider.DATASOURCE_TABLE_LOCK, SyncProvider.DATASOURCE_DB_LOCK
- Throws:
-
SyncProviderException
- if an error occurs determining the data source locking level. - See Also:
setDataSourceLock(int)
supportsUpdatableView
public abstract int supportsUpdatableView()
Returns whether this SyncProvider
implementation can perform synchronization between a RowSet
object and the SQL VIEW
in the data source from which the RowSet
object got its data.
- Returns:
- an
int
saying whether thisSyncProvider
object supports updating an SQLVIEW
; one of the following: SyncProvider.UPDATABLE_VIEW_SYNC, SyncProvider.NONUPDATABLE_VIEW_SYNC
getVersion
public abstract String getVersion()
Returns the release version of this SyncProvider
instance.
- Returns:
- a
String
detailing the release version of theSyncProvider
implementation
getVendor
public abstract String getVendor()
Returns the vendor name of this SyncProvider
instance
- Returns:
- a
String
detailing the vendor name of thisSyncProvider
implementation