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DBPool Service

This service creates and stores database connections so that they can be reused. Along with Transaction Service, DBPool manages transactions and synchronizes the transactions in the server with those in the database. DBPool Service provides support for JDBC 2.0 compliant drivers.

Visual Administrator

Runtime Control

The system administrator can manage and create database pools at runtime from the “Runtime” control tab of Visual Administrator.

It provides sufficient information about the existing pools, and an interface to create new ones.

General Tab

When creating new pools, relevant information must be submitted as an input to the following fields of the “Settings” pane:

• Pool name – specifies the name of the database pool
• Aliases – specifies alternative name of a registered pool; thus a single pool can be looked up with different names by a number of applications
• Database URL – specifies the location of the used database
• User – specifies the user that connects to the database
• Password – specifies the password to be associated with the particular user

To create a pool, you must specify an appropriate driver for it. In the “Driver” pane the following parameters must be specified:

• Driver – specifies driver implementation class for JDBC 1.x compliant drivers, and DataSource class for JDBC 2.0 compliant drivers
• Driver files – for JDBC 2.0 compliant drivers this parameter specifies an archive that contains the required files for DataSource object
• Factory – specifies XADataSource factory classname, and is obligatory for JDBC 2.0 compliant drivers
• CpdsName – specifies classname of XADataSource instance (usually the same classname specified in the “Driver” field), and is obligatory for JDBC 2.0 compliant drivers

There are also options to start or stop, delete, or edit pools. These actions are performed by the following options, which are located in the left-hand pane of the “Runtime” tab:

• Start/Stop – this opens a selected pool from the list of registered ones. If the selected pool has been opened, it closes the pool.
• Remove – removes a selected pool
• Change – edits the properties of a selected pool

Additional Tab

The “Driver specific properties” pane in this tab refers to JDBC 2.0-compliant drivers. You can specify properties that are required for the relevant JDBC 2.0-compliant driver you use – for example, serverName , portNumber , and so on. The driver-specific properties are entered  as key-value pairs. In addition, DBPool Service enables support for two types of JDBC 2.0-compliant drivers. The first type of drivers – for example, Oracle and MSSQL drivers, require the XAResource not to be delisted before the transaction is committed or rolled back. The other type of drivers – for example, Merant SequeLink driver, require XAResource delistment before the transaction is completed. The following property refers to this:

• DelistBeforeCompletion – it takes a boolean value (“true” or “false”). Set the value of this property to “false,” if you use a driver of the first type; otherwise, set the property value to “true.”

The following properties refer to connection pooling:

• Default conn – specifies the default number of connections to be established
• Max conn – specifies the maximum number of connections to be established
• Init conn – specifies the number of connections to be created at pool creation time
• Expire timeout – specifies the time in seconds after which a connection is removed from the pool if not used
• Expire thread – specifies the time interval in seconds at which threads are started to check for connections that have expired

Note: These properties may be set only if the “pooling” indicator is set. This means that a cache for connections is used.

The following properties refer to “Transaction Support”:

• Default Isolation – this drop-down menu provides options to choose the transaction isolation level. The available options are
• NONE (default value)
• TRANSACTION_READ_UNCOMMITED
• TRANSACTION_READ_COMMITED
• TRANSACTION_REPEATABLE_READ
• TRANSACTION_SERIALIZABLE XAPool – if the “XAPool” indicator is set, distributed transactions are supported. It is set as default.
• Enable fake 2PC – this option enables distributed transactions when the server is connected to more than one database, or when SAP J2EE Engine 6.20 is running in cluster mode.

Properties

There are no service-specific properties to be set by the system administrator.

Console Administrator

DBPool Service can be administered using the Shell commands from the DBPOOL command group as well.

Note: For information on DBPOOL shell commands, refer to the Shell  Commands Reference section.

Property Files

../cluster/server/services/dbpool/properties
This file does not contain any properties to be set by the system administrator.

Critical Information and Troubleshooting Tips

Special attention must be paid to configuring “Connection Pooling” and “Transaction support” properties of the DBPool Service.

It is recommended that you do not use “Connection Pooling” when the driver itself supports pooling. Such use deteriorates performance. The system administrator must be familiar with the driver-specific features.

The values of other properties in “Connection Pooling” must also be specified in accordance with system resources available to achieve optimal performance.

It is not always appropriate to use the “Transaction Support” properties. When the pool is not used in a transaction, this property must be inactive to achieve better performance. However, this is a rare case. That is why the Transaction support property is active by default.