Data Mapper Mediator

Data Mapper mediator is a data mapping solution that can be integrated into a mediation sequence. It converts and transforms one data format to another, or changes the structure of the data in a message. It provides WSO2 Integration Studio with a graphical mapping configuration and generates the files required for executing this graphical mapping configuration through the WSO2 Data Mapper engine.

WSO2 Data Mapper is an independent component that does not depend on any other WSO2 product. However, other products can use the Data Mapper to achieve/offer data mapping capabilities. Data Mapper Mediator is the intermediate component, which gives the data mapping capability into WSO2 Micro Integrator.

Data Mapper mediator finds the configuration files from the Registry and configures the Data Mapper Engine with the input message type (XML/JSON/CSV) and output message type (XML/JSON/CSV). Then it takes the request message from the Micro Integrator message flow and uses the configured Data Mapper Engine to execute the transformation and adds the output message to the Micro Integrator message flow.


The Data Mapper mediator is a content-aware mediator.


<datamapper config="gov:datamapper/FoodMapping.dmc" inputSchema="gov:datamapper/FoodMapping_inputSchema.json" inputType="XML" outputSchema="gov:datamapper/FoodMapping_outputSchema.json" outputType="XML"/> 


The parameters available for configuring the Data Mapper mediator are as follows.

Parameter name Description
Mapping Configuration The file, which contains the script file that is used to execute the mapping. You need to create a mapping configuration file using WSO2 Integration Studio and store it either in the Configuration Registry or Governance Registry to select and upload it from here.
Input Schema JSON schema, which represents the input message format. You need to create an input schema file using WSO2 Integration Studio and store it either in the Configuration Registry or Governance Registry to select and upload it from here.
Output Schema JSON schema, which represents the output message format. You need to create an output schema file using the WSO2 Integration Studio plugin, and store it either in the Configuration Registry or Governance Registry to select and upload it from here.
Input Type Expected input message type (XML/JSON/CSV)


By default, the Input type for the Data Mapper is XML regardless of the Input Schema Type. Therefore, based on your requirement, you may need to change the Input Type manually.

Output Type Target output message type (XML/JSON/CSV)


By default, the Output Type for the Data Mapper is XML regardless of the Output Schema Type. Therefore, based on your requirement, you may need to change the Output Type manually.

Components of Data Mapper

WSO2 Data Mapper consists of two components. They are the Data Mapper Tooling and the Data Mapper Engine.

Data Mapper Tooling

The Data Mapper Tooling component is the interface used to create configuration files that are required by the Data Mapper Engine to execute the mapping. Following configuration files are needed by the Data Mapper engine.

  • Input schema file (<data_mapper_name>_inputSchema.json)
  • Output schema file (<data_mapper_name>_outputSchema.json)
  • Mapping configuration file (<data_mapper_name>.dmc)
  • XSLT stylesheet (<data_mapper_name>_xsltStyleSheet.xml) - This is applicable only when using XML to XML transformations.

These files are generated by the Data Mapper Tool and saved in a Registry Resource project, which you deploy in WSO2 Micro Integrator as shown in the example below.

Generated configuration files


  • The .datamapper and .datamapper_diagram files as shown in the example above contain meta data related to the Data Mapper diagram.
    They are ignored when you deploy the project to a server to be used by the Data Mapper Engine.
  • Only the two schema files and the .dmc (Data Mapper Configuration) file gets deployed.
  • The XSLT stylesheet is an auto-generated file that optimizes XML to XML transformation. Optimization of XML to XML transformation is enabled by default.


XML to XML transformation is incorrect
The XML to XML tranformation optimization is enabled by default to increase performance. However, if your XML to XML transformation is not happening as anticipated (e.g, the data mapping related to the XML to XML tranformation is incorrect for certain scenarios), disable the XML to XML tranformation optimization as follows:

  1. Click on the <data_mapper_name>_xsltStyleSheet.xml file.
  2. Change the xmlns:notXSLTCompatible property in the XSLT stylesheet to true.
    This will disable the XML to XML tranformation optimization.

Input and output schema files

Input and output schema files are custom-defined JSON schemas that define the input/output format of input/output messages. The Data Mapper tool generates them when loading the input and output files as shown below.


You can also create the input and output JSON Schemas manually using the Data Mapper Diagram Editor. For instructions, see Creating a JSON Schema Manually.

You can load the following input/output message formats:


When loading a sample input XML file, you cannot have the default namespace (i.e. without a prefix in the namespace element). Also, you need to use the same prefix in all occurrences that refer to the same namespace within one XML file. For example, see the use of the prefix axis2ns11 in the example below.

Sample input XML file:

<?xml version="1.0" encoding="utf-8"?>
<soapenv:Envelope xmlns:soapenv="">
    <axis2ns11:LimitInfoHeader xmlns:axis2ns11="">
            <axis2ns11:type>API REQUESTS</axis2ns11:type>
    <axis2ns11:records xmlns:axis2ns11="" xmlns:xsi="" xsi:type="sf:sObject">
    <sf:type xmlns:sf="">Account</sf:type>
    <sf:Id xmlns:sf="">001E0000002SFO2IAO</sf:Id>
    <sf:CreatedDate xmlns:sf="">2011-03-15T00:15:00.000Z</sf:CreatedDate>
    <sf:Id xmlns:sf="">001E0000002SFO2IAO</sf:Id>
    <sf:Name xmlns:sf="">WSO2</sf:Name>
  • XML: to load a sample XML file
  • JSON: to load a sample JSON file
  • CSV: to load a sample CSV file with column names as the first record
  • JSONSCHEMA: to load a WSO2 Data Mapper JSON schema
  • CONNECTOR: to use Data Mapper with Connectors. Connectors will contain JSON schemas for each operation that defines the message formats to which it will respond and expect. Therefore, when you integrate connectors in a project this Connector option searches through the workspace and find the available Connectors. Then, you can select the respective Connector in the operation, so that the related JSON schema will be loaded for the Data Mapper by the tool.

Mapping configuration file

This is a JavaScript file generated by looking at the diagram you draw in the Data Mapper Diagram Editor by connecting input elements to output elements. Every operation you define in the diagram gets converted to a JavaScript operation.

Data Mapper Engine

You need the following information to configure the Data Mapper Engine:

  • Input message type
  • Output message type
  • Input schema Java Scripting API
  • Output schema
  • Mapping configuration

At the runtime, the Data Mapper Engine gets the input message and the runtime variable map object and outputs the transformed message. The Data Mapper Engine uses the Java Scripting API, to execute the mapping configuration. Therefore, if your runtime is JAVA 7, it uses the Rhino JS Engine and if your runtime is JAVA 8, it uses the Nashorn JS engine.

When you use JAVA 7, there are several limitations in the Rhino engine that directly affects the Data mapper Engine. There are several functions that Rhino does not support. F or example, String object functions like startsWith() and endsWith() . Therefore, the Rhino engine may have limitations in executing those when using custom functions and operators.

Using product-specific runtime variables

Also, the Data Mapper engine allows you to use runtime product-specific variables in the mapping. The intermediate component should construct a map object containing runtime product-specific variables and send it to the Data Mapper Engine, thereby, when the mapping happens in the Data Mapper Engine, these variables become available.

For example, the Data Mapper mediator provides properties like axis2/transport/synapse/axis2client/operation/. . In the Data Mapper diagram, you can use the Property operator and define the scope and the property name and use it in the mapping. Then, the Data Mapper mediator will identify the required properties to execute the mapping and populate a map with the required properties and will send it to the Data Mapper Engine.

Data Mapper element and attribute types

Following are the element and attribute types that are supported by the Data Mapper.

  • {} - represents object elements
  • [] - represents array elements
  • \<> - represents primitive field values
  • A - represents XML attribute values

Data Mapper operations

The operations palette placed in the left-hand side of the WSO2 Data Mapping Diagram Editor displays the operations that the Data Mapper supports as shown below .

You can drag and drop these operations to the Editor area. There are six categories of operations as follows:

  • Links
  • Common
  • Arithmetic
  • Conditional
  • Boolean
  • Type Conversion
  • String

Data Mapping Link: maps elements with other operators and elements.


Constant: defines String, number or boolean constant values.

Custom Function: defines custom functions to use in the mapping.

Properties: uses product-specific runtime variables.

Global Variable: instantiates global variables that you can access from anywhere.

Compare: compares two inputs in the mapping.


Add: adds two numbers.

Subtract: subtracts two or more numbers.

Multiply: multiplies two or more numbers.

Divide: divides two numbers.

Ceiling: derives the ceiling value of a number (closest larger integer value).

Floor: derives the floor value of a number (closest lower integer value).

Round: derives the nearest integer value.

Set Precision: formats a number into a specified length.

Absolute Value: derives the absolute value of a rational number.

Min: derives the minimum number from given inputs

Max: derives the maximum number from given inputs


IfElse: uses a condition and selects one input from given two.


AND: performs the boolean AND operation on inputs.

OR: performs the boolean OR operation on inputs.

NOT: performs the boolean NOT operation on inputs.

Type conversion

StringToNumber: converts a String value to number (“0” -> 0).

StringToBoolean: converts a String value to boolean (“true” -> true).

ToString: converts a number or a boolean value to String.


Concat: concatenates two or more Strings.

Split: splits a String by a matching String value.

Uppercase: converts a String to uppercase letters.

Lowercase: converts a String to lowercase letters.

String Length: gets the length of the String.

StartsWith: checks whether a String starts with a specific value. (This is not supported in Java 7.)

EndsWith: checks whether String ends with a specific value. (This is not supported in Java 7.)

Substring: extracts a part of the String value.

Trim: removes white spaces from the beginning and end of a String.

Replace: replaces the first occurrence of a target String with another.

Match – check whether the input match with a (JS) Regular Expression

AI Data Mapper

WSO2 Integration Studio allows you to seamlessly generate the input-output mapping using its sophisticated AI Data Mapping generator. You simply have to load the input and output to the relevant sections as shown below and click Apply. Alternatively, you can manually create the mapping using the graphical drag-and-drop tool.


The AI Data Mapping generator uploads the data to an internal WSO2 server for processing. However, your data is not stored by WSO2.

example one Data mapper diagram


Example 1 - Creating a SOAP payload with namespaces

This example creates a Salesforce login SOAP payload using a JSON payload. The login payload consists of XML namespaces. Even though the JSON payload does not contain any namespace information, the output JSON schema will be generated with XML namespace information using the provided SOAP payload.

example one Data mapper diagram

The sample input JSON payload is as follows.


The sample output XML is as follows.

<soapenv:Envelope xmlns:urn="" xmlns:soapenv="">
      <urn:username><b>[email protected]</b></urn:username>

Example 2 - Mapping SOAP header elements

This example demonstrates how to map SOAP header elements along with SOAP body elements to create a certain SOAP payload, by creating a Salesforce convertLead SOAP payload using a JSON payload. The Convert Lead SOAP payload needs mapping SOAP header information.
E.g. <urn:sessionId>QwWsHJyTPW.1pd0_jXlNKOSU</urn:sessionId>

The sample input JSON payload is as follows.

   "opportunityName":"Partner Opportunity",

The sample output XML is as follows.

<?xml version="1.0" encoding="utf-8"?>  
<soapenv:Envelope xmlns:urn="" xmlns:soapenv="">
     <urn:convertLead >
        <urn:leadConverts> <!-- Zero or more repetitions -->
           <urn:opportunityName>Partner Opportunity</urn:opportunityName>

Example 3 - Mapping primitive types

This example demonstrates how you can map an XML payload with integer, boolean etc. values into a JSON payload with required primitive types, by specifying the required primitive type in the JSON schema.

The sample input XML payload is as follows.

<?xml version="1.0" encoding="UTF-8" ?>

The sample output JSON is as follows.

"name" : "app_name",
"version" : "version",
"manifest_version" : 2,
"description" : "description_text",
"container" : "GOOGLE_DRIVE",
"api_console_project_id" : "YOUR_APP_ID",
"gdrive_mime_types": {
  "": [
      "type": ["image/png", "image/jpeg", "image/gif", "application/",
      "href": "http://your_web_url/",
      "title" : "Open",
      "disposition" : "window"
"icons": {
  "128": "icon_128.png"
"app" : {
  "launch" : {
  "web_url" : ""

Example 4 - Mapping XML to CSV

This example demonstrates how you can map an XML payload to CSV format.


If you specify special characters (e.g., & , &amp; ) within the <text> tag w hen converting from CSV to CSV , they will be displayed as follows by default. - & -> &amp; - &amp; -> &amp;amp; - < -> &lt; - &lt; -> &lt;lt;

To avoid this and to display the exact special characters as text in the returned output, add the following properties in the Synapse configuration.

<property name="messageType" value="text/plain" scope="axis2"/>
<property name="ContentType" value="text/plain" scope="axis2"/>

The sample in put XML payload is as follows.

<?xml version="1.0"?>
<PurchaseOrder PurchaseOrderNumber="001">
    <Name>James Yee</Name>
    <Street>Downtown Bartow</Street>
    <City>Old Town</City>
    <Name>Elen Smith</Name>
    <Street>123 Maple Street</Street>
    <City>Mill Valley</City>
 <DeliveryNotes>Please leave packages in shed by driveway.</DeliveryNotes>

The sample out put CSV is as follows.

James Yee,Downtown Bartow,Old Town,PA,95819,USA
Ellen Smith,123 Maple Street,Mill Valley,CA,10999,USA

Example 5 - Mapping XSD to JSON

This example demonstrates how you can map an XSD payload to JSON format.

example 5 mapping

The sample in put XSD payload is as follows.

<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="">
  <xs:element name="books">
        <xs:element name="book">
              <xs:element type="xs:string" name="id"/>
              <xs:element type="xs:string" name="author"/>
              <xs:element type="xs:string" name="title"/>
              <xs:element type="xs:float" name="price"/>

The sample out put JSON is as follows.

  "books": {
    "book": {
      "id": "001",
      "author": "Writer",
      "title": "Great book on nature",
      "price": "44.95"