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You should define each agent that you will use to communicate events in the Event Manager. Each agent's name must be unique within its system. The agent can be referenced in code within Oracle Workflow by a compound name in the following format:

<agent_name>@<system_name>

For example, the agent WF_IN within the system HUB could be referenced as WF_IN@HUB.

After defining the agents on your local system, you should set them up for event message propagation by scheduling listeners for local inbound agents and propagation for local outbound agents. See: Scheduling Listeners for Local Inbound Agents, Oracle Workflow Administrator's Guide and Scheduling Propagation for Local Outbound Agents, Oracle Workflow Administrator's Guide.

Assigning a Direction to an Agent

• In--Inbound communication to the system. The agent receives messages in a specific protocol and presents them to the system in a standard format.

• Out--Outbound communication from the system. The agent accepts messages from the system in a standard format and sends them using the specified protocol.

Assigning a Protocol to an Agent

A protocol can represent a network standard, such as SQLNET. It can also represent a business-to-business standard that defines the higher-level message format and handshaking agreements between systems in addition to the network standard.

The Business Event System interacts with an agent through an AQ queue. You can use AQ to perform the propagation of messages by the SQLNET protocol which it supports. In Oracle9i Database and higher, AQ also includes Internet access functionality that lets you perform AQ operations over the Internet by using AQ's Internet Data Access Presentation (IDAP) for messages and transmitting the messages over the Internet using transport protocols such as HTTP or HTTPS. Additionally, the Messaging Gateway feature of AQ in Oracle9i Database and higher enables communication between applications based on non-Oracle messaging systems and AQ, letting you integrate with third party messaging solutions. You can also implement other services to propagate messages by different protocols.

To implement a custom protocol, you must perform the following steps:

1. Define AQ queues to hold pending inbound and outbound messages.

2. Provide code that propagates messages to and from the AQ queues.

3. Define a lookup code for the new protocol in the Event Protocol Type (WF_AQ_PROTOCOLS) lookup type, which is stored in the Standard item type. The Event Manager uses the Event Protocol Type lookup type to validate the protocol for an agent. See: To Create Lookup Codes for a Lookup Type.

4. Define agents with the new protocol. See: To Define an Agent.

<schema>.<queue>@<database link>

In this format, <schema> represents the schema that owns the queue, <queue> represents the queue name, and <database link> represents the name of the database link to the instance where the queue is located.

Note: You must enter the database link name exactly as the name was specified when the database link was created. For example, if a database link is named ORA816.US.ORACLE.COM, you must enter that complete name in the address of an agent on that database. You cannot abbreviate the name to ORA816.

The names of the database links that you want to use for the Business Event System should be fully qualified with the domain names. To confirm the names of your database links, use the following syntax:

			SELECT db_link FROM all_db_links

See: Creating Database Links, Oracle Workflow Administrator's Guide.

Assigning a Queue to an Agent

Event messages within the Oracle Workflow Business Event System are encoded in a standard format defined by the datatype WF_EVENT_T. You must assign each agent a PL/SQL package called a queue handler that translates between this standard Workflow format and the format required by the agent's queue. See: Event Message Structure, Oracle Workflow API Reference.

Note: Even if the agent's queue uses WF_EVENT_T as its payload type, a queue handler is still required in order to set native AQ message properties.

Oracle Workflow provides two standard queue handlers, called WF_EVENT_QH and WF_ERROR_QH, for queues that use SQLNET propagation and use the WF_EVENT_T datatype as their payload type. You can use WF_EVENT_QH with queues that handle normal Business Event System processing, while WF_ERROR_QH should be used exclusively with error queues.

Oracle Workflow also provides a standard queue handler called WF_EVENT_OJMSTEXT_QH for queues that use the SYS.AQ$_JMS_TEXT_MESSAGE datatype as their payload type. This queue handler enables communication of JMS Text messages through the Business Event System. See: Mapping Between WF_EVENT_T and SYS.AQ$_JMS_TEXT_MESSAGEE, Oracle Workflow API Reference.

If you want to use queues that require a different format, create a custom queue handler for that format. Your custom queue handler must include a set of standard APIs to enqueue and dequeue messages in the custom format. See: Standard APIs for a Queue Handler.

Standard Agents

• WF_CONTROL - Oracle Workflow internal agent, not for customer use

• WF_DEFERRED - Standard agent for deferred subscription processing

• WF_ERROR - Standard agent for error handling

• WF_IN - Default inbound agent

• WF_JMS_IN - Default inbound agent for JMS Text messages

• WF_JMS_OUT - Default outbound agent for JMS Text messages

• WF_NOTIFICATION_IN - Standard inbound agent for e-mail notification responses

• WF_NOTIFICATION_OUT - Standard outbound agent for e-mail notifications

• WF_OUT - Default outbound agent

You can enable or disable the WF_IN, WF_JMS_IN, WF_OUT, and WF_JMS_OUT agents, but you must not make any other changes to their definitions. You must not make any changes to the definitions of the other agents.

Oracle Workflow automatically runs agent listener service components for the standard WF_DEFERRED, WF_ERROR, and WF_NOTIFICATION_IN agents in order to perform deferred subscription processing, error handling for the Business Event System, and inbound e-mail processing for notification mailers, respectively. If you want to use the WF_IN, WF_JMS_IN, WF_OUT, and WF_JMS_OUT agents for event message propagation, schedule listeners for WF_IN and WF_JMS_IN and propagation for WF_OUT and WF_JMS_OUT as well. You do not need to schedule propagation for the WF_CONTROL and WF_NOTIFICATION_OUT agents, however, because the middle tier processes that use WF_CONTROL dequeue messages directly from its queue, and notification mailers send messages placed on the WF_NOTIFICATION_OUT queue. See: Scheduling Listeners for Local Inbound Agents, Oracle Workflow Administrator's Guide and Scheduling Propagation for Local Outbound Agents, Oracle Workflow Administrator's Guide.

Note: Oracle Workflow includes three additional agents named WF_REPLAY_IN, WF_REPLAY_OUT, and WF_SMTP_O_1_QUEUE, which are not currently used. Oracle Workflow also includes agents named WF_JAVA_DEFERRED, WF_JAVA_ERROR, WF_WS_JMS_IN, and WF_WS_JMS_OUT, which are currently used only in Oracle Applications.

The following table lists the default properties for the standard WF_CONTROL agent. See: Cleaning Up the Workflow Control Queue, Oracle Workflow Administrator's Guide.

Agent Property	Value
Name	WF_CONTROL
Display Name	Workflow Control Out Queue
Description	Workflow JMS Text Message Queue used to signal messages to middle tier processes
Protocol	SQLNET
Address	<workflow schema>.WF_CONTROL@<local database>
System	<local system>
Queue Handler	WF_EVENT_OJMSTEXT_QH
Queue Name	<workflow schema>.WF_CONTROL
Direction	Out
Status	Enabled

The following table lists the default properties for the standard WF_DEFERRED agent.

Agent Property	Value
Name	WF_DEFERRED
Display Name	WF_DEFERRED
Description	WF_DEFERRED
Protocol	SQLNET
Address	<workflow schema>.WF_DEFERRED@<local database>
System	<local system>
Queue Handler	WF_EVENT_QH
Queue Name	<workflow schema>.WF_DEFERRED
Direction	In
Status	Enabled

The following table lists the default properties for the standard WF_ERROR agent.

Agent Property	Value
Name	WF_ERROR
Display Name	WF_ERROR
Description	WF_ERROR
Protocol	SQLNET
Address	<workflow schema>.WF_ERROR@<local database>
System	<local system>
Queue Handler	WF_ERROR_QH
Queue Name	<workflow schema>.WF_ERROR
Direction	In
Status	Enabled

The following table lists the default properties for the standard WF_IN agent.

Agent Property	Value
Name	WF_IN
Display Name	WF_IN
Description	WF_IN
Protocol	SQLNET
Address	<workflow schema>.WF_IN@<local database>
System	<local system>
Queue Handler	WF_EVENT_QH
Queue Name	<workflow schema>.WF_IN
Direction	In
Status	Enabled

The following table lists the default properties for the standard WF_JMS_IN agent.

Agent Property	Value
Name	WF_JMS_IN
Display Name	Workflow JMS In Queue
Description	Workflow JMS Text Message Queue
Protocol	SQLNET
Address	<workflow schema>.WF_JMS_IN@<local database>
System	<local system>
Queue Handler	WF_EVENT_OJMSTEXT_QH
Queue Name	<workflow schema>.WF_JMS_IN
Direction	In
Status	Enabled

The following table lists the default properties for the standard WF_JMS_OUT agent.

Agent Property	Value
Name	WF_JMS_OUT
Display Name	Workflow JMS Out Queue
Description	Workflow JMS Text Message Queue
Protocol	SQLNET
Address	<workflow schema>.WF_JMS_OUT@<local database>
System	<local system>
Queue Handler	WF_EVENT_OJMSTEXT_QH
Queue Name	<workflow schema>.WF_JMS_OUT
Direction	Out
Status	Enabled

The following table lists the default properties for the standard WF_NOTIFICATION_IN agent. See: Implementing Notification Mailers, Oracle Workflow Administrator's Guide.

Agent Property	Value
Name	WF_NOTIFICATION_IN
Display Name	Workflow Notification In Queue
Description	Workflow inbound notification response queue
Protocol	SQLNET
Address	<workflow schema>.WF_NOTIFICATION_IN@ <local database>
System	<local system>
Queue Handler	WF_EVENT_OJMSTEXT_QH
Queue Name	<workflow schema>.WF_NOTIFICATION_IN
Direction	In
Status	Enabled

The following table lists the default properties for the standard WF_NOTIFICATION_OUT agent. See: Implementing Notification Mailers, Oracle Workflow Administrator's Guide.

Agent Property	Value
Name	WF_NOTIFICATION_OUT
Display Name	Workflow Notification Out Queue
Description	Workflow notification outbound queue
Protocol	SQLNET
Address	<workflow schema>.WF_NOTIFICATION_OUT@ <local database>
System	<local system>
Queue Handler	WF_EVENT_OJMSTEXT_QH
Queue Name	<workflow schema>.WF_NOTIFICATION_OUT
Direction	Out
Status	Enabled

The following table lists the default properties for the standard WF_OUT agent.

Agent Property	Value
Name	WF_OUT
Display Name	WF_OUT
Description	WF_OUT
Protocol	SQLNET
Address	<workflow schema>.WF_OUT@<local database>
System	<local system>
Queue Handler	WF_EVENT_QH
Queue Name	<workflow schema>.WF_OUT
Direction	Out
Status	Enabled

See Also

To Find Agents

To Update or Delete an Agent