what is event header in Context

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what is event header in Context

When we publish an event, whether there is an common event header attached on each event. 

Gerardo Pardo's picture
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Joined: 06/02/2010
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All data published by DDS has a common header called the SampleInfo which contains things like the timestamp, sequence number, indetification of the source, etc. See SampleInfo. Beyond this there is no "event header per se". However in DDS you get to define the data-types so when you define the event type you can define any "header fields" you see fit. 

Note also that unlike other pub-sub messaging technologies DDS can do content filtering / routing on the whole body of the message, so there is no real differentiation between putting things on a "message header" versus the body. This is a powerful concept because you do not need to anticipate at design-time which things belong to the "header" or the "body" just define the event type with all the information you need.