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From "Jonathan Anstey (JIRA)" <>
Subject [jira] Commented: (CAMEL-1106) Add enrich() processor to implement Content Enricher pattern
Date Wed, 11 Feb 2009 20:11:59 GMT


Jonathan Anstey commented on CAMEL-1106:

This feature has been added in CAMEL-209 so I'm closing this one.  

> Add enrich() processor to implement Content Enricher pattern
> ------------------------------------------------------------
>                 Key: CAMEL-1106
>                 URL:
>             Project: Apache Camel
>          Issue Type: New Feature
>          Components: camel-core
>    Affects Versions: 2.0.0
>            Reporter: Fintan Bolton
>            Assignee: Jonathan Anstey
>             Fix For: 2.0.0
>         Attachments:
> Add an enrich() processor with the following overloaded variants:
> 	from(<SourceURI>).enrich(<EnricherURI>)...
> 	from(<SourceURI>).enrich(<EnricherURI>, <Aggregator>)...
> 	from(<SourceURI>).enrich(<EnricherURI>, <Aggregator>, <CachingFlag>)...
> Motivation:
> -----------
> The motivation for this feature comes from a problem that Mark Fynes encountered while
trying to integrate an Artix Data Services example with Camel. The Artix DS example had multiple
inputs, but it turns out that it is difficult to represent an Artix DS transform with multiple
inputs in Camel.
> After thinking about it for a bit, I realized that the problem can be solved using the
Content Enricher EIP pattern. Currently, however, writing a Camel content enricher mostly
involves rolling your own code. The aim of the 'Content Enricher Pattern' is to generalize
the solution of Mark's problem so that you can create a content enricher quickly and easily
in the future.
> Use Case 1 - Enriching from a flat file:
> ----------------------------------------
> In the original example that Mark worked on, there were two sources of input:
> 1. A stream of credit card transactions (e.g. containing a Name, Credit Card Number,
TransactionAmount, and so on). This input can be represented by the start of a Camel route,
e.g. from(<SourceURI>).
> 2. An XML file containing credit ratings for different customers (e.g. a list of associations
between Names and credit ratings). This input represents the data that will be fed in through
the content enricher processor.
> The two sources of input could be handled by a new 'enrich()' processor, which is specified
as follows:
> 	from(<SourceURI>).enrich(<EnricherURI>, <Aggregator>, <CachingFlag>)...
> Where the <SourceURI> specifies the source of incoming credit card transactions
(e.g. from a message queue), <EnricherURI> specifies the flat file containing the credit
ratings, <Aggregator> is a Camel aggregator, and <CachingFlag> indicates whether
the flat file (from <EnricherURI>) should be read only once (true) or every time a transaction
comes in (false).
> For the <Aggregator>, probably the most generally useful implementation would be
a ListAggregator that combines the incoming exchange and the enricher exchange into a java.util.List
instance. The value list.get(0) would return the exchange from <SourceURI> and list.get(1)
would return the exchange from the <EnricherURI>.
> If you chain enrichers as follows:
> 	from(<SourceURI>)
> 		.enrich(<EnricherURI01>, listAggregator)
> 		.enrich(<EnricherURI02>, listAggregator)
> 		...
> You would obtain a list with list.get(0) from <SourceURI>, list.get(1) from <EnricherURI01>,
and list.get(2) from <EnricherURI02>.
> If you consider ListAggregator to be a good default, you could define the following overloaded
variants of enrich:
> 	enrich(<EnricherURI>)
> 	enrich(<EnricherURI>, <Aggregator>)
> 	enrich(<EnricherURI>, <Aggregator>, <CachingFlag>)
> Where the default value of <CachingFlag> probably ought to be true(?).
> Demo
> -------
> The attached ZIP file contains a partial demo of this functionality. To run the demo,
unzip the archive and run the command, 'mvn test'.

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