# JMS Header Fields

EMS supports the predefined JMS header fields.

For more information, see JMS Message Header Fields.

Note: The `JMSTimestamp` JMS header field is a special case.

The JMS header `JMSTimestamp` corresponds to the time when the message was created. If this header field is not present when the `tibemsd` receives the message, it sets `theJMSTimestamp` to the current time.

TIBCO FTL messages do not have destinations or subjects, or a mandatory set of predefined header fields. Instead, message fields and their values are set for individual messages.

If the `export_headers` is defined as `true` in the common EMS transport properties, the EMS server converts the JMS header fields and their values to TIBCO FTL fields and values and adds them to the outgoing message. This allows TIBCO FTL to use content matchers on the fields.

If the `export_headers` property is `false`, then the JMS header fields and their values are not included in the exported TIBCO FTL message. This includes the destination name. That is, if `export_headers = false` for the transport, then the message exported to TIBCO FTL will not contain the destination name.

When converting the JMS header fields to TIBCO FTL message fields, header fields are given the prefix `_emshdr`:. For example, the JMSDeliveryMode header field is assigned the field name `_emshdr:JMSDeliveryMode` when inserted into the TIBCO FTL message.

The following table presents the mapping of JMS header fields to TIBCO FTL message field name and types (that is, the name and type of the corresponding field in the exported message).

JMS Header Name | TIBCO FTL Field Name | FTL Field Type
--- | --- | ---
`JMSDestination` | `_emsHdr:JMSDestination` | char*
`JMSDeliveryMode` | `_emsHdr:JMSDeliveryMode` | tibint64_t
`JMSPriority` | `_emsHdr:JMSPriority` | tibint64_t
`JMSMessageID` | `_emsHdr:JMSMessageID` | char*
`JMSTimestamp` | `_emsHdr:JMSTimestamp` | tibint64_t
`JMSCorrelationID` | `_emsHdr:JMSCorrelationID` | char*
`JMSType` | `_emsHdr:JMSType` | char*
`JMSDeliveryTime` | `_emsHdr:JMSDeliveryTime` | tibint64_t
`JMSExpiration` | `_emsHdr:JMSExpiration` | tibint64_t
`JMSRedelivered` | `_emsHdr:JMSRedelivered` | tibint64_t
JMSReplyTo | `_emsHdr:`JMSReplyTo | char*

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