Data Change Notification With Payload and Without Payload

Understand the differences between DCN with payload and DCN without payload.

• DCN without payload – calls MBO operations, where the name used in the DCN request matches that of the MBO definition.

  

  1. The DCN requester sends an MBO operation execution request, along with operation parameters, to Unwired Server.
  2. Unwired Server executes the operation, (effectively calling the EIS operation), and updates the cache database (CDB), if needed, depending on the operation's cache update policy.
  3. Unwired Server returns a DCN status message to the requester.
  Note: Be careful when naming MBO operations in Unwired WorkSpace, for example, an EIS-affecting operation named "delete" may be easily confused with the direct cache-affecting operation named :delete.
• DCN with payload – calls only the two direct cache-affecting operations (:upsert or :delete), which always exist for an MBO, and are not related to user-defined MBO operations.
  • :upsert – the message must contain name/value pairs for every required attribute, and the name must exactly match the MBO attribute name.
  • :delete – provide only the name/value pairs for the primary key column(s).
  These operations respectively insert or update, or delete a row in the CDB. Calling either of these operations does not trigger any other refresh action. A typical sequence of events might be:

  

  1. Some event initiates the DCN request (a database trigger for example).
  2. The Unwired Server cache could be updated directly from the EIS, or the DCN request could originate from a source other than the EIS. The actual data (payload) is applied to the cache, through either an :upsert (update or insert) or a :delete operation.
  3. Unwired Server returns a DCN status message to the requester.

• Performance Considerations for DCN With Payload Versus Without Payload
  Performance is one factor to consider when determining whether to implement DCN with or without payload.