Messages typically consist of a payload and a message
header which contains any other message data required for the Service Engine to
understand and process the message (for example, security information). Again, we
can see that this provides a loosely coupled model in which Service Engines have no
prior knowledge of other Service Engines. This therefore allows the JBI architecture
to be flexible, and allows different component vendors to develop standard
based components.
Normalized Message Router enables technology for allowing messages to
be passed between loosely coupled services such as Service Engines.
The figure below gives an overview of the message routing between a client
application and two service engines, in this case the EE and SQL service engines.
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In this figure, a request is made from the client to the JBI Container. This request
is passed via NMR to the EE Service Engine. The EE Service Engine then makes
a request to the SQL Service Engine via NMR. The SQL Service Engine returns a
message to the EE Service Engine again via NMR. Finally, the message is routed back
to the client through NMR and JBI framework. The important concept here is that
NMR is a message routing hub not only between clients and service engines, but also
for intra-communication between different service engines.
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