JMS Header Setter mediation primitive

Use the Java Messaging Service Header Setter primitive to create, modify, copy or delete JMS message headers.

Introduction

You can use the JMS Header Setter mediation primitive to provide a mechanism for managing JMS headers in the message. You can change, copy, add, or delete JMS headers by setting the mediation primitive properties.

If you want multiple header changes you can set multiple actions. Multiple actions are acted on sequentially, in the order in which they are specified; this means that header changes can build on each other.

You can create new JMS headers by specifying header field values. You can search for JMS headers that already exist in the Service Message Object by specifying the header name to match on. If a matching header is found, it can then be deleted from the message, copied to another location in the SMO, or have the value set. If a matching header is not found, a new header can be created using a specified header field value.

The JMS Header Setter mediation primitive has one input terminal (in), one output terminal (out) and a fail terminal (fail). The in terminal is wired to accept a message and the other terminals are wired to propagate a message. If the mediation is successful, the out terminal propagates the modified message. If an exception occurs during the transformation, the fail terminal propagates the original message, together with any exception information contained in the failInfo element.

The JMS Header Setter mediation primitive uses the given header name to determine where to look in the SMO. There are two different types of JMS Header, distinguished by name and their location in the SMO.

Standard JMS Headers, which have their own schema in the SMO, located at /headers/JMSHeader.
Any other headers are User Headers and are listed at /headers/properties.

Usage

You can use the JMS Header Setter mediation primitive to ensure that when a JMS message is sent to another system, via the JMS binding, the headers that are sent with the message are correctly set.

Because the operations you define occur sequentially, a later operation can depend on an earlier operation. For example, you could create a new header, copy it to elsewhere in the SMO and then delete it from the list of headers it was initially appended to.

You can also use the JMS Header Setter mediation primitive to help to filter messages, using the Message Filter mediation primitive. You might want to find a particular header and make it available to be used in the filtering.

When sending JMS messages, the JMS specification places limitations on setting some standard headers. The following table lists the standard JMS headers and indicates how they can be set. Those headers that are generated automatically ignore any value present in the SMO JMS header.

Table 1. How to set a header in IBM Process Server, in priority order
Header field	How to set in Process Server (in priority order)
JMSDestination	SMO target address header or admin console or import binding configuration
JMSDeliveryMode	Import binding configuration or SMO JMSDeliveryMode header
JMSExpiration	Asynchronous invocation qualifier. For more information, see Asynchronous reliability qualifiers.
JMSPriority	Import binding configuration or SMO JMSPriority header
JMSMessageID	Generated automatically
JMSTimestamp	Generated automatically
JMSCorrelationID	Import binding configuration or SMO JMSCorrelationID header
JMSReplyTo	Import binding configuration
JMSType	Import binding configuration or SMO JMSType header
JMSRedelivered	Generated automatically