On Demand Consulting
Author: Ming Li

Abstract

Consider a scenario that you want to transform your XML message to JSON format whose schema is dynamical and cannot be defined in a XSD file. Then you can not just use a map node to do such transformation.
This article mainly describes how to transform an input with XML format to an output with JSON format in a different schema.

Basic Knowledge

1. How to create a given JSON object with MbElement

Here is the given JSON object.
 

  { "Books": [   ?  { "Name": "Steve Jobs",   ?    "ISBN": "1451648537",   ?    "Language": "English",   ?    "Format": [ "Hardcover", "Paperback", "Audiobook CD", "Audible" ] },   ?  { "Name": "Beautiful Whale",   ?    "ISBN": "1419703846",   ?    "Language": "English",   ?    "Format": [ "Hardcover" ] }   ] }  

Here is the code to create this JSON object

  MbElement jsonEle = outMessage.getRootElement().createElementAsLastChild(MbJSON.PARSER_NAME);   MbElement dataEle = jsonEle.createElementAsLastChild(MbJSON.OBJECT, MbJSON.DATA_ELEMENT_NAME, null);   MbElement booksEle = dataEle.createElementAsLastChild(MbJSON.ARRAY, "Books", null);   MbElement book1Ele = booksEle.createElementAsLastChild(MbJSON.OBJECT, MbJSON.ARRAY_ITEM_NAME, null);   book1Ele.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, "Name", "Steve Jobs");   book1Ele.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, "ISBN", "1451648537");   book1Ele.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, "Language", "English");   MbElement book1FormatEle = book1Ele.createElementAsLastChild(MbJSON.ARRAY, "Format", null);   book1FormatEle.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, MbJSON.ARRAY_ITEM_NAME, "Hardcover");   book1FormatEle.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, MbJSON.ARRAY_ITEM_NAME, "Paperback");   book1FormatEle.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, MbJSON.ARRAY_ITEM_NAME, "Audiobook CD");   book1FormatEle.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, MbJSON.ARRAY_ITEM_NAME, "Audible"); MbElement   book2Ele = booksEle.createElementAsLastChild(MbJSON.OBJECT, MbJSON.ARRAY_ITEM_NAME, null);   book2Ele.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, "Name", "Beautiful Whale");   book2Ele.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, "ISBN", "1419703846");   book2Ele.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, "Language", "English"); MbElement book2FormatEle =   book2Ele.createElementAsLastChild(MbJSON.ARRAY, "Format", null);   book2FormatEle.createElementAsLastChild(MbElement.TYPE_NAME_VALUE, MbJSON.ARRAY_ITEM_NAME, "Hardcover");

2. How to access values in a JSON object

  // Get the first book's name - "Steve Jobs"  String book1Name = message.getRootElement().getFirstElementByPath("JSON/Data/Books/Item/Name").getValueAsString();  See KLhttps://odc.supportportal.com/link/portal/5377/31053/Article/27994/How-to-use-XPath-with-JSON-messages-in-Java-nodes  			  // Get the second book's name - "Beautiful Whale"  MbElement booksEle = message.getRootElement().getLastChild().getLastChild().getLastChild();   String book2Name = booksEle.getFirstChild().getNextSibling().getFirstChild().getValueAsString();      

Transformation Sample


Requirement

All XML data is queried from a database, here is the database table

Empid Department FirstName LastName
1 Accounts John Doe
2 Accounts Ram Kumar
3 Accounts Joe Foster
4 Risk John Rowe
5 Risk Rob Conley
6 IT David Dickson
7 IT James Clear
8 IT Phil Viktor
9 IT Alfred Rich

The goal is to transform XML data to a JSON format as below. ?And the department names in JSON object are not supposed to be hard coded.

{
Accounts:{
Person:{
Empid: "1",
FirstName: "John",
LastName: "Doe"
}
Person:{
Empid: "2",
FirstName: "Ram",
LastName: "Kumar"
}
Person:{
Empid: "3",
FirstName: "Joe",
LastName: "Foster"
}
}
Risk:{
Person:{
Empid: "4",
FirstName: "John",
LastName: "Rowe"
}
Person:{
Empid: "5",
FirstName: "Rob",
LastName: "Conley"
}
}
IT:{
Person:{
Empid: "6",
FirstName: "David",
LastName: "Dickson"
}
Person:{
Empid: "7",
FirstName: "James",
LastName: "Clear"
}
Person:{
Empid: "8",
FirstName: "Phil",
LastName: "Viktor"
}
Person:{
Empid: "9",
FirstName: "Alfred",
LastName: "Rich"
}
}
}


Message Flow

We create the message flow starting with an HTTP Input and a map node to simulate the DB query. Then use Java Compute Node to do the transformation. Finally get the output JSON data from an HTTP Reply.



Map


Code in Java Compute Node

Here is the transformation code



Test it in Flow Exerciser




Reference

Creating a JSON message
https://www.ibm.com/support/knowledgecenter/en/SSMKHH_10.0.0/com.ibm.etools.mft.doc/bc28411_.htm

Accessing elements in a message tree from a JavaCompute node
https://www.ibm.com/support/knowledgecenter/en/SSMKHH_10.0.0/com.ibm.etools.mft.doc/ac30330_.htm

Appendix

You can find it in attachment to see the whole example.