iluwatar#1627 adding more info in README.md

fanout-fanin/README.md

@@ -1,23 +1,28 @@
 ---
 layout: pattern
-title: FanOut-FanIn 
+title: Fan-Out/Fan-In
 folder: fanout-fanin
 permalink: /patterns/fanout-fanin/
-categories: Concurrency
+categories: Integration
 language: en
 tags:
-- Cloud distributed
-- Performance
+- Microservices
 ---
 
 ## Intent
-The pattern that refers to executing multiple instances of the activity function concurrently. Generally "FanOut" 
-process is splitting the data into multiple chunks that would be passed to the activity function. "FanIn" process is 
-basically aggregating the result from individual instance of activity function and forming a single final result. <br />
+The pattern is used when a source system needs to run one or more long-running process that will fetch some data. 
+Source will not block itself waiting for the reply. <br> The pattern will run the same function in multiple 
+services or machines to fetch the data. This is equivalent to invoking the function multiple times on different chunks of data.  
 
-Each activity function is a long-running process that takes in a chunk of data. A callback function, or a Consumer 
-is passed to the activity function, that will be called when the long-running process gets over. The consumer will 
-process the individual return value from activity function as they are done running into a final result.
+## Explanation
+The FanOut/FanIn service will take in a list of requests and a consumer. Each request might complete at different time.
+FanOut/FanIn service will accept the input params and returns the initial system an ID to acknowledge that the pattern
+service has received the requests. Now the caller will not wait or expect the result in the same connection. 
+
+Meanwhile, the pattern service will invoke the requests that have come. The requests might complete at different time. 
+These requests will be processed in different instances of the same function in different machines or services. As the 
+requests get completed, a callback service everytime is called that transforms the result into a common format, or a single object 
+that gets pushed to a consumer. That caller will be at the other end of the consumer receiving the result.
 
 ## Class diagram
 ![alt-text](./etc/fanout-fanin.png)
@@ -26,6 +31,11 @@ process the individual return value from activity function as they are done runn
 
 Use this pattern when you can chunk the workload or load into multiple chunks that can be dealt with separately.
 
+## Related patterns
+
+- Aggregator Microservices
+- API Gateway
+
 ## Credits
 
 * [Understanding Azure Durable Functions - Part 8: The Fan Out/Fan In Pattern](http://dontcodetired.com/blog/post/Understanding-Azure-Durable-Functions-Part-8-The-Fan-OutFan-In-Pattern)