Detailed explanation about the enricher in Mule with example

2.  Enricher is used if the target system needs more information than
the source system can provide.
 It enriches the mule message by calling external system or do
some transformation to existing payload and save it into some
scope of variable like session or outbound or invocation and the
transformation happened in en-richer scope doesn't affect the
actual payload.

3.  Set-property: Save some information extracted from payload or
original payload to some invocation or flow scope variable.
 NOTE: Mule currently supports enrichment of flow variables and
message headers only.
Example:
 Consider a message from a source system contains a zip code but
the target system needs the two letter state. A message enricher
can be used to lookup the state using the zip (postal code) from an
enrichment resource. The enricher calls out to the enrichment
resource with the current message (containing the zip code) then
enriches the current message with the result.

4. Example Flow:

5.  This is a very simple flow with one-way inbound and outbound
endpoints, and which acts as part of an order processing pipeline. This
flow uses an enricher to add a state flow variable to the current
message with the state that the flow ref returns. The ‘target’ attribute
defines how the current message is enriched using
a MessageEnricher which uses the same syntax as expression
evaluators.

6. Description:
 1. The http endpoint receives an xml input as a payload with H-No,
street, city and zip elements.
 2. In message enricher we modified the payload as zip and
forwarded the same to sub flow to retrieve the state for that particular
zip.
 3. The flow reference in the processor chain of the enricher receives
the state as a payload which enricher assigns to a new target flow
variable named state.
 4. The payload sent from the enricher is the same as the input
payload and the new state variable is added to the xml using Data-
Mapper.

7. Output:

8.  The enricher element also supports more advanced use cases
where the message returned by the enrichment resource isn’t just a
simple string which is exactly what we need to enrich the current
message with; often you may want to enrich your message with just
part of the information from the result of the invocation of an
external service.
More Complex Enrichment

9.  In this particular example the ‘Get State’ endpoint receives the
full message, and we are supposed to use a part of that
payload. Here we mention the part of the payload in the Source
section of the Message Enricher and that is saved in the target
section.

10.  The “enrichment resource” can be any message processor,
outbound connector, processor-chain or flow-ref. If using an
outbound-connector then of course it should have a request-
response exchange pattern.

11. Thank You All