Github user bhupeshchawda commented on a diff in the pull request:
https://github.com/apache/apex-malhar/pull/353#discussion_r72930798
--- Diff: docs/operators/enricher.md ---
@@ -0,0 +1,169 @@
+POJO Enricher
+=============
+
+## Operator Objective
+This operator receives an POJO ([Plain Old Java
Object](https://en.wikipedia.org/wiki/Plain_Old_Java_Object)) as an incoming
tuple and uses an external source to enrich the data in
+the incoming tuple and finally emits the enriched data as a new enriched
POJO.
+
+POJOEnricher supports enrichment from following external sources:
+
+1. **JSON File Based** - Reads the file in memory having content stored in
JSON format and use that to enrich the data. This can be done using FSLoader
implementation.
+2. **JDBC Based** - Any JDBC store can act as an external entity to which
enricher can request data for enriching incoming tuples. This can be done using
JDBCLoader implementation.
+
+POJO Enricher does not hold any state and is **idempotent**,
**fault-tolerance** and **statically/dynamically partitionable**.
+
+## Operator Usecase
+1. Bank ***transaction records*** usually contains customerId. For further
analysis of transaction one wants the customer name and other customer related
information.
+Such information is present in another database. One could enrich the
transaction's record with customer information using POJOEnricher.
+2. ***Call Data Record (CDR)*** contains only mobile/telephone numbers of
the customer. Customer information is missing in CDR. POJO Enricher can be used
to enricher
+CDR with customer data for further analysis.
+
+## Operator Information
+1. Operator location: ***malhar-contrib***
+2. Available since: ***3.4.0***
+3. Operator state: ***Evolving***
+3. Java Packages:
+ * Operator:
***[com.datatorrent.contrib.enrich.POJOEnricher](https://www.datatorrent.com/docs/apidocs/com/datatorrent/contrib/enrich/POJOEnricher.html)***
+ * FSLoader:
***[com.datatorrent.contrib.enrich.FSLoader](https://www.datatorrent.com/docs/apidocs/com/datatorrent/contrib/enrich/FSLoader.html)***
+ * JDBCLoader:
***[com.datatorrent.contrib.enrich.JDBCLoader](https://www.datatorrent.com/docs/apidocs/com/datatorrent/contrib/enrich/JDBCLoader.html)***
+
+## Properties, Attributes and Ports
+### <a name="props"></a>Properties of POJOEnricher
+| **Property** | **Description** | **Type** | **Mandatory** | **Default
Value** |
+| -------- | ----------- | ---- | ------------------ | ------------- |
+| *includeFields* | List of fields from database that needs to be added to
output POJO. | List<String\> | Yes | N/A |
+| *lookupFields* | List of fields from input POJO which will form a
*unique composite* key for querying to database | List<String\> | Yes | N/A |
--- End diff --
Will composite key work for JSON?
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