Oracle Workflow Developer's Guide Release 2.6.3 Part Number B10284-02 |
![]() |
![]() |
![]() |
![]() |
![]() |
||
Previous | Next | Contents | Index | Glossary |
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 communication by scheduling agent listeners for local inbound agents and propagation for local outbound agents. You can use Oracle Enterprise Manager to schedule propagation and the Workflow Manager component of Oracle Applications Manager to run agent listeners. You can also view the distribution of event messages on different agents in Workflow Manager, as well as reviewing queue details for those agents. For more information, please refer to the Oracle Applications Manager online help, Oracle Enterprise Manager Support, Oracle Application Developer's Guide - Advanced Queuing or Oracle Streams Advanced Queuing User's Guide and Reference, Distributed Management, Oracle Enterprise Manager Administrator's Guide, and Setting Up the Business Event System, Oracle Workflow Administrator's Guide.
You can also use the Event System Local Queues page to review the local queues used by the Business Event System as well as the messages currently being held on those queues. See: Reviewing Local Queues.
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. The following table shows which services you can use for various protocols, depending on your database version.
Database Version | SQLNET Protocol | HTTP/HTTPS Protocols | Integration with Third Party Messaging Solutions |
---|---|---|---|
Oracle8i Database | Oracle Advanced Queuing | Oracle Message Broker | Oracle Message Broker |
Oracle9i Database and higher | Oracle Advanced Queuing | Oracle Advanced Queuing | Oracle Advanced Queuing Messaging Gateway feature |
<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.
Event messages within the Oracle Workflow Business Event System are encoded in a standard format defined by the datatype WF_EVENT_T. You should 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.
Additionally, Oracle Workflow provides a queue handler called WF_EVENT_OMB_QH, which you can use if you implement Oracle Message Broker with Oracle8i Database to propagate messages between systems by another protocol such as HTTP. See: Setting Up the WF_EVENT_OMB_QH Queue Handler, Oracle Workflow Administrator's Guide and Mapping Between WF_EVENT_T and OMBAQ_TEXT_MSG, 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.
Agent groups can only be used for inbound communication. All agent groups have a direction of In, and only individual agents with a direction of In can be members of an agent group.
You must associate each agent group with a system to which it belongs. However, you can include agents on other systems within the group.
Ensure that you run an agent listener for each agent within the group to receive inbound messages.
Note: You cannot run an agent listener for an agent group. Agent listeners can be run only for individual agents.
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 mailesr, 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. For more information, please refer to the Oracle Applications Manager online help, Oracle Enterprise Manager Support, Oracle Application Developer's Guide - Advanced Queuing or Oracle Streams Advanced Queuing User's Guide and Reference, Distributed Management, Oracle Enterprise Manager Administrator's Guide, and Setting Up the Business Event System, Oracle Workflow Administrator's Guide.
Note: Oracle Workflow also includes three additional agents named WF_REPLAY_IN, WF_REPLAY_OUT, and WF_SMTP_O_1_QUEUE, which are not currently used.
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 |
For communication between two systems that both have Oracle Workflow installed, Oracle Workflow provides an external system registration procedure that you can use to automatically copy the inbound agent definitions for the other system into the Event Manager of your local system. See: Registering External Systems.
If your local Workflow-enabled system will communicate with a non-Workflow system, the non-Workflow system must provide its own external propagation agents to handle Business Event System event messages.
To Create or Update an Agent Group
Previous | Next | Contents | Index | Glossary |