WebLogic Server 5.1.0 API Reference

bea.jolt.pool
Class SessionPool

java.lang.Object
  |
  +--bea.jolt.pool.Factory
        |
        +--bea.jolt.pool.SessionPool

Direct Known Subclasses:

ServletSessionPool

public class SessionPool

extends bea.jolt.pool.Factory

This class represents a session pool that contains one or more connections (sessions) to a BEA TUXEDO system. Service requests are sent to the BEA TUXEDO system via the session pool that distributes requests across its available connections.

This class provides several methods that are part of the session pool administrative API. When using session pools with BEA WebLogic, administration is done via the BEA WebLogic console. A user does not need to access this administrative API directly.

The call and startTransaction methods are not part of the administrative API. They are used to submit requests to a BEA TUXEDO system.

Multiple service requests can be executed in a single transaction. When a transaction starts, the session pool picks the least busy connection and puts it in transactional mode. All service requests associated with that transaction are then sent via the selected connection. The connection associated with the transaction is not available for other requests until the transaction either commits or aborts. The transaction should commit or abort before a response is sent to the client, otherwise the connection does not return to the pool of available connections.

A session pool attempts to reestablish failed connections. When a connection fails, in-process transactions and requests fail and return errors. The session pool only reestablishes connections, it does not resubmit failed requests.

Refer to the BEA WebLogic Administrators Guide for information on configuring a session pool.

Author:

Copyright (c) 1999 by BEA Systems, Inc. All Rights Reserved.
Copyright © 2000 BEA Systems, Inc. All Rights Reserved.

Constructor Summary

protected

SessionPool(java.lang.String[] addrs, java.lang.String[] saddrs, int minCons, int maxCons, UserInfo usr, boolean keepAlive) Creates a session pool with multiple connections to the BEA Jolt servers.

Method Summary

Result	call(java.lang.String svcname, DataSet input, Transaction tran) Invokes a BEA TUXEDO service.
protected Result	call(java.lang.String svcname, java.lang.String[] input, Transaction tran) Invokes a BEA TUXEDO service.
Connection	getConnection(int index) This method is part of the session pool administrative API.
protected bea.jolt.JoltDefinition	getDefinition(java.lang.String name) Gets a service definition.
int	getMaxConnections() This method is part of the session pool administrative API.
boolean	isSuspended() This method is part of the session pool administrative API.
protected void	log(java.lang.String msg) Logs an error message.
protected DataSet	newDataSet(int initCapacity, boolean flag) A default factory for the DataSet.
protected Result	newResult(int initCapacity) A default factory for the Result.
int	setMaxConnections(int maxCons) This method is part of the session pool administrative API.
Transaction	startTransaction(int timeout) Starts a transaction.

Methods inherited from class bea.jolt.pool.Factory

useException

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SessionPool

protected SessionPool(java.lang.String[] addrs,
                      java.lang.String[] saddrs,
                      int minCons,
                      int maxCons,
                      UserInfo usr,
                      boolean keepAlive)

Creates a session pool with multiple connections to the BEA Jolt servers. Each connection is associated with a server address selected from the primary server address list using a round-robin scheme. The secondary server address list is provided for fail-over. In order to shorten the start-up time, a minimum number of connections can be established at the start-up. The keepAlive parameter keeps the session alive by re-establishing any disconnected connection. This constructor is used by the session pool manager.

Parameters:

addrs - List of server addresses

saddrs - List of secondary server addresses for failover

minCons - Minimum number of connections

maxCons - Maximum number of connections

usr - User authenication info, or null

keepalive - true to keep the session alive

Method Detail

call

protected Result call(java.lang.String svcname,
                      java.lang.String[] input,
                      Transaction tran)
               throws SessionPoolException,
                      ApplicationException,
                      ServiceException,
                      TransactionException

Invokes a BEA TUXEDO service. The name of the service to be invoked is specified as a parameter to this method. Input parameters to the service are passed as an array of Strings. Each String in the array should be formatted as name=value, where name is the name of the service parameter and value is the value of the parameter. Names that do not match a parameter in the BEA TUXEDO service definition are ignored. To specify multiple occurrences of a name append _ to name. For example, to specify the first and second occurrence of a parameter "ACCOUNT_ID", set name to "ACCOUNT_ID_0" and "ACCOUNT_ID_1" respectively. If no input parameters are required for the BEA TUXEDO service, the input parameter should null.

To invoke multiple services in a transaction, create a Transaction object (see startTransaction()) and pass the Transaction object as the parameter to this method. If this service is not part of a transaction this parameter should be null.

If the session pool is suspended or if no connections are available, this method throws a SessionPoolException.

Parameters:

svcname - Name of the BEA TUXEDO service to be invoked

input - String[] of name=value pairs, or null if no input parameters

tran - A Transaction object, or null if no transaction

Returns:

A Result object, or null

See Also:

call(java.lang.String, bea.jolt.pool.DataSet, bea.jolt.pool.Transaction), startTransaction(int)

call

public Result call(java.lang.String svcname,
                   DataSet input,
                   Transaction tran)
            throws SessionPoolException,
                   ApplicationException,
                   ServiceException,
                   TransactionException

Invokes a BEA TUXEDO service. The name of the service to be invoked is passed to this method as a String svcname. Input parameters for the service are passed in input. If no input parameters are required for the service, input should be null. The names of the elements in the input must match the names of the service parameters.

To invoke multiple services in a transaction, create a Transaction object (see startTransaction()) and pass the Transaction object as the parameter tran. If this service is not part of a transaction tran should be null.

If the session pool is suspended or if no connections are available, this method throws a SessionPoolException.

Parameters:

svcname - Name of the service to be invoked

input - DataSet containing service parameters, or null if no input parameters

tran - Transaction object, or null if no transaction

Returns:

Result object, or null

See Also:

ServletSessionPool.call(java.lang.String, javax.servlet.http.HttpServletRequest, bea.jolt.pool.Transaction), ServletSessionPool.call(java.lang.String, javax.servlet.http.HttpServletRequest), startTransaction(int)

startTransaction

public Transaction startTransaction(int timeout)
                             throws SessionPoolException,
                                    TransactionException

Starts a transaction. The transaction starts on one of the connections in the session pool. Once a transaction starts on a connection, that connection cannot service requests other than those associated with the started transaction. The transaction must end (commit, abort or timeout) before the connection returns to the pool of available connections. The transaction timeout value is specified in seconds.

Parameters:

timeout - Transaction time-out value in seconds

Returns:

Transaction object

See Also:

call(java.lang.String, bea.jolt.pool.DataSet, bea.jolt.pool.Transaction), ServletSessionPool.call(java.lang.String, javax.servlet.http.HttpServletRequest, bea.jolt.pool.Transaction)

setMaxConnections

public int setMaxConnections(int maxCons)

This method is part of the session pool administrative API. It changes the maximum number of connections for a session pool. The number of connections in a session pool can only be increased using this method; shrinking the session pool is not allowed. This method returns -1 if the caller attempts to shrink the pool size.

Parameters:

maxCons - New session pool size

Returns:

New spool size, or -1 for errors

getMaxConnections

public int getMaxConnections()

This method is part of the session pool administrative API. It returns the maximum number of connections configured in this session pool. The actual number of established connections might be less than the maximum number configured, since connections are created dynamically depending on load.

Returns:

Configured maximum number of connections

isSuspended

public boolean isSuspended()

This method is part of the session pool administrative API. It checks if this session pool is suspended. A suspended session pool does not accept any new requests.

Returns:

true if the session pool is suspended; otherwise, false

See Also:

SessionPoolManager.suspendSessionPool(java.lang.String, boolean)

getConnection

public Connection getConnection(int index)

This method is part of the session pool administrative API. It returns the connection at index from the session pool. The parameter index must be between zero and maxCons-1 as specified in bea.jolt.pool.SessionPoolManager.createSessionPool.

Parameters:

index - A connection index

Returns:

A Connection object.

getDefinition

protected bea.jolt.JoltDefinition getDefinition(java.lang.String name)

Gets a service definition.

Parameters:

name - Service name

Returns:

A definition object, or null if not found.

newDataSet

protected DataSet newDataSet(int initCapacity,
                             boolean flag)

A default factory for the DataSet. This method should be overriden by the web-server specific method.

newResult

protected Result newResult(int initCapacity)

A default factory for the Result. This method should be overriden by the web-server specific method.

Overrides:

newResult in class bea.jolt.pool.Factory

log

protected void log(java.lang.String msg)

Logs an error message. This method should be overridden, so a web-server specific session can provide its logging facility.

Parameters:

msg - Error message to be logged