#114 Aggregator pattern; tests; description

eip-aggregator/README.md

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+---
+layout: pattern
+title: EIP Aggregator
+folder: eip-aggregator
+permalink: /patterns/eip-aggregator/
+categories: Enterprise integration
+tags:
+ - Java
+ - Difficulty-Intermittent
+ - Enterprise integration
+---
+
+## Intent
+Sometimes in enterprise systems there is a need to group incoming data in order to process it as a whole. For example
+you may need to gather offers and after defined number of offers has been received you would like to choose the one with
+the best parameters. 
+
+Aggregator allows you to merge messages based on defined criteria and parameters. It gathers original messages, 
+applies aggregation strategy and upon fulfilling given criteria, releasing merged messages.
+ 
+![alt text](./etc/aggregator.gif "Splitter")
+
+## Applicability
+Use the Aggregator pattern when
+
+* You need to combine multiple incoming messages 
+* You want to process grouped data
+
+## Credits
+
+* [Gregor Hohpe, Bobby Woolf - Enterprise Integration Patterns](http://www.enterpriseintegrationpatterns.com/patterns/messaging/Aggregator.html)
+* [Apache Camel - Documentation](http://camel.apache.org/aggregator2.html)
+