Chapter 6 Connectors

A connector module (also called a resource adapter), is a Java component that enables applications to interact with enterprise information systems (EISs). EIS software includes various types of systems: enterprise resource planning (ERP), mainframe transaction processing, and non-relational databases, among others. To install a connector module you deploy it, as you do for other Java modules.

A connector connection pool is a group of reusable connections for a particular EIS. To create a connector connection pool, specify the connector module (resource adapter) that is associated with the pool.

A connector resource is a program object that provides an application with a connection to an EIS. To create a connector resource, specify its JNDI name and its associated connection pool. Multiple connector resources can specify a single connection pool. The application locates the resource by looking up its JNDI name. The JNDI name of a connector resource for an EIS is usually in the java:comp/env/eis-specific subcontext. Application Server 9 implements JMS by using a connector module (resource adapter)

This chapter covers:

Connector Connection Pools

The following table describes connection pool settings:

Parameter	Description
Initial and Minimum Pool Size	The minimum number of connections in the pool. This value also determines the number of connections placed in the pool when the pool is first created or when application server starts.
Maximum Pool Size	The maximum number of connections in the pool.
Pool Resize Quantity	When the pool shrinks toward the minimum pool size it is resized in batches. This value determines the number of connections in the batch. Making this value too large will delay connection recycling; making it too small will be less efficient.
Idle Timeout	The maximum time in seconds that a connection can remain idle in the pool. After this time expires, the connection will be removed from the pool.
Max Wait Time	The amount of time the application that has requested a connection will wait before getting a connection time-out. Because the default wait time is long, the application might appear to hang indefinitely.
On Any Failure	If you select the checkbox labelled Close All Connections, if a single connection fails, then the application server will close all connections in the pool and then reestablish them. If you do not select the checkbox, then individual connections will be reestablished only when they are used.
Transaction Support	Use the Transaction Support list to select the type of transaction support for the connection pool. The chosen transaction support overrides the transaction support attribute in the resource adapter associated with this connection pool in a downward compatible way. In other words, it can support a lower transaction level than that specified in the resource adapter or the same transaction level as that specified in resource adapter, but it cannot specify a higher level. The None selection from the Transaction Support menu indicates that the resource adapter does not support resource manager local or JTA transactions and does not implement `XAResource` or `LocalTransaction` interfaces. For JAXR resource adapters, you need to choose None from the Transaction Support menu. JAXR resource adapters do not support local or JTA transactions. Local transaction support means that the resource adapter supports local transactions by implementing the `LocalTransaction` interface. Local transactions are managed internal to a resource manager and involve no external transaction managers. XA transaction support means that the resource adapter supports resource manager local and JTA transactions by implementing the `LocalTransaction` and `XAResource` interfaces. XA transactions are controlled and coordinated by a transaction manager external to a resource manager. Local transactions are managed internal to a resource manager and involve no external transaction managers.
Connector Validation	Select the Enabled checkbox if you want the connection pool to be validated before being passed on to the application.

Before creating a connection pool, you need to deploy the connector module (resource adapter) associated with the pool. You can deploy a connector module using the Admin Console or by using the asadmin command. For information about the asadmincommand see, asadmin(1M)

To view, create, edit, or delete connection pools in the Admin Console, click Resources > Connectors > Connector Connection Pools. You can add properties (a name-value pair) to a connector connection pool. Alternatively, you can use the following asadmin commands to create and delete connection pools:

Connector Resources

A connector resource provides an application with a connection to an Enterprise Information System (EIS). Every connector resource is associated with a connection pool. To view, create, edit, or delete connector resources, click Resources > Connectors > Connector Resources in the Admin Console. Alternatively, you can use the following asadmin commands to create and delete connection resources:

Administered Object Resources

An administered object provides an application with specialized functionality, such as access to a parser specific to the resource adapter and its associated EIS. To view, create, edit, or delete administered objects, click Resources > Connectors > Admin Object Resources in the Admin Console.