IBM BPM, V8.0.1, All platforms > Programming IBM BPM > Enterprise Service Bus programming > WebSphere MQ binding > Access the WebSphere MQ header
Use a mediation flow component to access the WebSphere MQ header
In WebSphere ESB, the MQ Header Setter mediation primitive provides a mechanism for managing MQ headers in a message.
You can change, copy, add, or delete WebSphere MQ headers by setting the mediation primitive properties as shown in Figure 1.
Figure 1. MQ Header Setter mediation primitive
properties 
If you need to change multiple headers, you can set multiple actions. Multiple actions are processed sequentially, in the order you specify. The MQ Header Setter mediation primitive does not provide control of the MQMD header, which you can change using the MessageElementSetter, and Mapping mediation primitives.
Although you can modify all fields of the MQMD within a mediation flow component, the WebSphere MQ binding overrides some of the fields, when the message is sent to WebSphere MQ. The following list of fields, override by default:
- MsgType
- MsgID
- BackoutCount
- ReplyToQ
- ReplyToQMgr
- UserIdentifier
- AccountingToken
- ApplIdentityData
- PutApplType
- PutApplName
- PutDate
- PutTime
- ApplOriginData
- GroupId
- MsgSeqNumber
- Offset
- OriginalLength
You can propagate the following list of MQMD fields by setting the custom property MDCTX=SET_ALL_CONTEXT on the Java Naming and Directory Interface (JNDI) queue definition, as specified in the import or export:
- UserIdentifier
- AppIdentityData
- PutApplType
- PutApplName
- ApplOriginData
You can propagate the following list of MQMD fields by editing message configuration properties on the WebSphere MQ Import binding:
- MsgID - request Message ID options must be set to copy from a SCA message.
- MsgType -
Clear the check box for the property: Set the message type to MQMT_DATAGRAM or MQMT_REQUEST for request-response operations.
- ReplyToQ - Select the check box for the property: Override the reply to queue of request message.
- ReplyToQMgr - Select the check box for the property: Override the reply to the queue of the request message. You can optionally define a queue manager.
You cannot propagate the following MQMD fields to the outbound WebSphere MQ message:
- BackoutCount
- AccountingToken
- PutDate
- PutTime
- Offset
- OriginalLength