Using Data Mapper Mediator in WSO2 EI

Prerequisites

Set up the following prerequisites before you begin.

• Download and run WSO2 EI. For instructions on running the WSO2 ESB server, see Running the Product.
• Install the WSO2 Developer Studio ESB Tool 5.0.0 to use the Data Mapper mediator, which supports the data mapping editor. For instructions on installing this, see Installing Enterprise Integrator Tooling.  
• Download and launch a REST client into your web browser. For example, this guide uses the Postman REST client to send the requests to WSO2 ESB and receive the responses.

Introduction

This sample demonstrates how to create a mapping configuration for different data formats using the Data Mapper mediator. It uses a simple WSO2 ESB configuration with only a Data Mapper mediator, and a Respond mediator to check the converted message. The input employee message in XML format, and the output engineer message in JSON format, which is sent to the client as the response.

Creating the ESB configuration project

Follow the steps below to create an ESB configuration project to contain the Data Mapping configurations using the WSO2 Developer Studio ESB Tool.

1. Open the WSO2 Developer Studio ESB Tool.

2. Right click on the Project Explorer area, click New, and then click EI Solution Project as shown below.

   WSO2 EI Tooling now provides this new option to create an EI Solution Project for you to define all different configurations you need for the project using a wizard.

   

3. Enter a name for the project, and untick Create Connector Exporter Project (since you do not need Connectors in your configuration) in the following wizard page.
    
4. Click Finish.You view the following project files created in the Project Explorer tab.
   
5. Right click EIDataMappingProject workspace file, click New, and then click REST API as shown below, to create a new REST API project in WSO2 ESB.
   
   
   Select Create A New API Artifact, and then click Finish as shown below.
   
6. Enter a name for the Synapse API Artifact, enter /convertMenu for Context to configure the REST API project to listen for POST requests on the /convertMenu URL, and then click Finish as shown below.
   
7. Drag and drop a Data Mapper mediator and a Respond mediator as shown below. 
   
   
8.  Click on the API Resource, and then click on its Properties tab, and select True as the value for the Post method as shown below, to create the API resource listening to POST requests.
   
9. Double click on the Data Mapping mediator, to configure it. You view a dialog box to create a registry resource project.

10. Enter a name for the configuration, and point the Registry Resource project to save it as shown below.

    This configuration name is the prefix used for the configuration files that you deploy to the EI server related to the Data Mapper. Since you created an EI Solution project, it directly points you to that project to save in it. Otherwise, you need to click the Create new project link, to create a new Registry Resource project and then point to it.

    

11. Click OK. You view the following Data Mapper diagram editor in the new WSO2 Data Mapper Graphical perspective.

    You can switch to another perspective by either selecting another in top toolbar tags or by clicking Window->Perspective->Open Perspective->Other in the top menu bar.

    
    

12.  Create an XML file by copying the following sample content of a food menu, and save it in your local file system.

    Use this sample XML message to load the input format to the Data Mapper editor.   

    <?xml version="1.0" encoding="UTF-8"?>
    <breakfast_menu>
        <food>
            <name>Belgian Waffles</name>
            <price>$5.95</price>
            <description>Two of our famous Belgian Waffles with plenty of real maple syrup</description>
            <calories>650</calories>
            <orgin>Belgian</orgin>
            <veg>true</veg>
        </food>
        <food>
            <name>Strawberry Belgian Waffles</name>
            <price>$7.95</price>
            <description>Light Belgian waffles covered with strawberries and whipped cream</description>
            <calories>900</calories>
            <orgin>Belgian</orgin>
            <veg>true</veg>
        </food>
        <food>
            <name>Berry-Berry Belgian Waffles</name>
            <price>$8.95</price>
            <description>Light Belgian waffles covered with an assortment of fresh berries and whipped cream</description>
            <calories>900</calories>
            <orgin>Belgian</orgin>
            <veg>true</veg>
        </food>
        <food>
            <name>French Toast</name>
            <price>$4.50</price>
            <description>Thick slices made from our homemade sourdough bread</description>
            <calories>600</calories>
            <orgin>French</orgin>
            <veg>true</veg>
        </food>
        <food>
            <name>Homestyle Breakfast</name>
            <price>$6.95</price>
            <description>Two eggs, bacon or sausage, toast, and our ever-popular hash browns</description>
            <calories>950</calories>
            <orgin>French</orgin>
            <veg>false</veg>
        </food>
    </breakfast_menu>

13. Right-click on the top title bar of the Input box and, click Load Input as shown below. The operation palettes that appear on the left-hand side allows you to provide the input message format to begin the mapping. 
    

14. Select XML as the Resource Type as shown below.

    You can select one out of the following resource types, to load the input and output message formats to Data Mapper.

    • XML: to load a sample XML message and WSO2 Data Mapper Editor will generate the JSON schema to represent the XML according to the WSO2 Data Mapper Schema specification.  
    • JSON: to load a sample JSON message. 
    • CSV: to load a sample JSON/CSV message.  For CSV you need to provide the column names as the first record.
    • XSD: to load an XSD schema file, which defines your XML message format.
    • JSONSCHEMA: to load a JSON schema for your message according to the WSO2 Data Mapper schema specification.
    • CONNECTOR: to map a message, which is an output of a Connector. Select the Connector Type  in the Input box, and it will list down all available connectors. Then, select the operation from the menu that appears in front of Data Mapper mediator. 

    

15. Click the file system link in Select resource from, select the XML file you saved in your local file system in step 12, and click Open. 
    You view the input format loaded in the Input box in the editor as shown below. 

    

16. Create another XML file by copying the following sample content of a food menu, and save it in your local file system. 
    

    Use this sample XML message to load the output format to the Data Mapper editor.   

    <?xml version="1.0" encoding="UTF-8"?>
    <menu>
        <item>
            <name>Belgian Waffles</name>
            <price>$5.95</price>
            <calories>650</calories>
            <orgin>Belgian</orgin>
            <veg>true</veg>
            <description>Two of our famous Belgian Waffles with plenty of real maple syrup</description>
        </item>
        <item>
            <name>Strawberry Belgian Waffles</name>
            <price>$7.95</price>
            <calories>900</calories>
            <orgin>Belgian</orgin>
            <veg>true</veg>
            <description>Light Belgian waffles covered with strawberries and whipped cream</description>
        </item>
        <item>
            <name>Berry-Berry Belgian Waffles</name>
            <price>$8.95</price>
            <calories>900</calories>
            <orgin>Belgian</orgin>
            <veg>true</veg>
            <description>Light Belgian waffles covered with an assortment of fresh berries and whipped cream</description>
        </item>
        <item>
            <name>French Toast</name>
            <price>$4.50</price>
            <calories>600</calories>
            <orgin>French</orgin>
            <veg>true</veg>
            <description>Thick slices made from our homemade sourdough bread</description>
        </item>
        <item>
            <name>Homestyle Breakfast</name>
            <price>$6.95</price>
            <calories>950</calories>
            <orgin>French</orgin>
            <veg>false</veg>
            <description>Two eggs, bacon or sausage, toast, and our ever-popular hash browns</description>
        </item>
    </menu>

17. Right-click on the top title bar of the Output box and, click Load Output as shown below. The operation palettes that appear on the left-hand side allows you to provide the output message format.
    
    
18. Click the file system link in Select resource from, select the XML file you saved in your local file system in step 16, and click Open.  
    You view the input format loaded in the Output box in the editor as shown below. 
    
    
19. Check the Input and Output boxes with the sample messages, to see if the element types (i.e. (Arrays, Objects and Primitive values) are correctly identified or not. Following signs will help you to identify them correctly.
    
    • {} - represents object elements
    • [] - represents array elements
      
    • <> - represents primitive field values
    • A - represents XML attribute values

20. Do the mapping as preferred using operators as shown in the example below.  

    You can only connect primitive data values such as Strings, numbers, boolean and etc. You cannot map Array and object values.

    The mapping done in the below example is that, name is mapped via uppercase operator and calories undergoes a mathematical calculation to get the output as follows:

    output calories =Round( (calories*1.13) + 6.75)

    

21. Press Ctrl+S keys in each tab, to save all the configurations. 

Deploying the configurations

After creating the Data Mapper configurations, follow the steps below to deploy the created REST API and the configurations in the WSO2 ESB server by including them in a C-App.

1. Open the WSO2 Developer Studio ESB Tool.
   

2. Expand the C-APP project that was created when you created the EI Solution project (i.e. EIDataMappingProjectCompositeApplication), and double-click on the POM file. You view the following screen to select project files into the C-APP. 

   You need to refresh the screen to view the registry resource files . Once you refresh the screen, you view all the artifacts in the workspace. 

    

   

3. Click the refresh button in the top right-hand corner to load newly added registry files, as shown below.

   

4. Select the REST API file and the three registry resource files containing the mapping configuration, input schema, and output schema as shown below. 
    
   • Configuration: Script file that is used to execute the mapping.
   • Input schema: JSON schema which represents the input message format.
   • Output schema: JSON schema which represents the output message format.
   
5. Click on the Data Mapper mediator.  You view the following in the Properties tab of the Data Mapper mediator configuration as shown below.
   
   • Configuration: Script file that is used to execute the mapping.
   • Input Schema: JSON schema, which represents the input message format.
   • Output Schema: JSON schema, which represents the output message format.
   • Input Type: Expected input message type (xml/json/csv).
   • Output Type: Target output message type (xml/json/csv).

   

   If your mapping failed during runtime, check if the input type and output type are set correctly in the mediator configuration.

6. Start WSO2 ESB server. For instructions, see Running the Product.
7. Click the Servers Tab in the  WSO2 Developer Studio ESB Tool, and click the No servers are available. Click this link to create a new server... link as shown below.  
   
8. Click WSO2, click WSO2 Carbon remote server, and then click Next  as shown below.  
   
   
9.  Enter the URL of WSO2 ESB for Server URL, and click Finish as shown below.
   You view the WSO2 ESB server added in the Servers tab as shown below.  
   
10. Right-click on WSO2 Carbon remote server at localhost, and then click Add & Remove.
11. Select the C-App in the Available: box, click Add to move it to the Configured: box, and then click Finish as shown below.  
    You view the C-App added to the WSO2 ESB server as shown below.  
     
12. Log in to the WSO2 ESB Management Console using the following URL and admin/admin credentials: https://<ESB_HOST>:<ESB_PORT>carbon/
13. Click Main, and then click APIs in the Service Bus menu. You view the deployed  REST API invocation URL as shown below.  
    

Invoking the created REST API

Follow the steps below to test invoking the created REST API.

1. Open Postman REST client.
2. Enter the following details to create the client message, enter the content of the XML file you created in step 12 as the payload in the text area provided, and click Send as shown below. 
   
   • URL: http://<ESB_HOST>:<ESB_PORT>8280/convertMenu
   • Method: POST
   • Body: raw xml/application
   • Message: Enter the inpu

   
   You view the expected JSON message received as shown below.