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 to create a graphical mapping configuration and generates the files required to execute this graphical mapping configuration by 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 you need for that, which gives the data mapping capability into the ESB profile of WSO2 EI.

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 ESB profile message flow and uses the configured Data Mapper Engine to execute the transformation and adds the output message to the ESB profile message flow.

The Data Mapper mediator is a content-aware mediator.

Prerequisites

You need to install the WSO2 Integration Studio to use the Data Mapper mediator. For instructions on installing this Plugin, see Installing WSO2 Integration Studio.

Syntax

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

Configuration

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 the WSO2 Integration Studio plugin, 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 the WSO2 Integration Studio plugin, 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)
Output Type	Target output message type (XML/JSON/CSV)

Components of Data Mapper

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

Data Mapper Tooling

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 three configuration files are needed by the Data Mapper engine.

Input schema file
Output schema file
Mapping configuration file

These three files are generated by the Data Mapper Tool and saved in a Registry Resource project, which you deploy in a WSO2 server 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) get deployed.

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="http://schemas.xmlsoap.org/soap/envelope/">
<soapenv:Header>
    <axis2ns11:LimitInfoHeader xmlns:axis2ns11="urn:partner.soap.sforce.com">
        <axis2ns11:limitInfo>
            <axis2ns11:current>42336</axis2ns11:current>
            <axis2ns11:limit>83000</axis2ns11:limit>
            <axis2ns11:type>API REQUESTS</axis2ns11:type>
        </axis2ns11:limitInfo>
    </axis2ns11:LimitInfoHeader>
</soapenv:Header>
<soapenv:Body>
    <axis2ns11:records xmlns:axis2ns11="urn:partner.soap.sforce.com" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="sf:sObject">
    <sf:type xmlns:sf="urn:sobject.partner.soap.sforce.com">Account</sf:type>
    <sf:Id xmlns:sf="urn:sobject.partner.soap.sforce.com">001E0000002SFO2IAO</sf:Id>
    <sf:CreatedDate xmlns:sf="urn:sobject.partner.soap.sforce.com">2011-03-15T00:15:00.000Z</sf:CreatedDate>
    <sf:Id xmlns:sf="urn:sobject.partner.soap.sforce.com">001E0000002SFO2IAO</sf:Id>
    <sf:Name xmlns:sf="urn:sobject.partner.soap.sforce.com">WSO2</sf:Name>
</axis2ns11:records>
</soapenv:Body>
</soapenv:Envelope>

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 WSO2 EI 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, t o 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. For 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.