WSO2 ESB - Data Mapper Mediator

Scenario:

Tools:

• WSO2 ESB 5.0.0
• WSO2 Developer Studio ESB Tool 5.0.0

Creating the ESB configuration project

1. 1. Open the WSO2 Developer Studio ESB Tool.

1. 2. Right click on the Project Explorer area, click New, and then click  ESB Solution Project 
2. 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.

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   5. Right click DataMappingExample project workspace file, click New, and then click REST API, to create a new REST API project in WSO2 ESB.
2. 6. Select Create A New API Artifact, and then click Finish as shown below.
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   7. 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.
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   8. Drag and drop a Data Mapper mediator and a Respond mediator as shown below. 
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   9. 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. 
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7. 10. Double click on the Data Mapping mediator. You can see a dialog box to create a registry resource project.
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9. 11. Enter a name for the configuration, and point the Registry Resource project to save it.
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11. 12. This configuration name is the prefix used for the configuration files that you deploy to the ESB server related to the Data Mapper. Since you created an ESB 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.
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12. 13. Click  OK. You view the following Data Mapper diagram editor in the new WSO2 Data Mapper Graphical perspective. 
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15. 14. Create an XML file by copying the following sample content of a food menu and save it in your local file system.

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

1. <?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>

2. 14. Right-click on the top title bar of the Input box and, click Load Input. The operation palettes that appear on the left-hand side allows you to provide the input message format to begin the mapping
   • 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. 
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15. Click the file system link in Select resource from, select the XML file you saved in your local file system and click Open.  
You view the input format loaded in the Input box in the editor.
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   Select XML as the Resource Type.
5. 16. Create another XML file by copying the following sample content of a food menu, and save it in your local file system.
6. Use this sample XML message to load the output format to the Data Mapper editor. 
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9. <?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>

11. 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.
    Click the file system link in Select resource from, select the XML file you saved in your local file system, and click Open.  You view the input format loaded in the Output box in the editor as shown below.

14. 18. Check the Input and Output boxes with the sample messages, to see if the element types (Ex:Arrays, Objects and Primitive values) are correctly identified or not. Following signs will help you to identify them correctly. 
15. {} - represents object elements
16. [] - represents array elements
17. <> - represents primitive field values
18. A - represents XML attribute values
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20. 19. Do the mapping as preferred using operators as shown in the example below.
21. You can only connect primitive data values such as Strings, numbers, boolean and etc. You cannot map Array and object values.
22. 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)
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26. 20. Press Ctrl+S keys in each tab, to save all the configurations

Deploying the configurations

1. 1. 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.
2. 2. Open the WSO2 Developer Studio ESB Tool.
3. 3. Expand the C-APP project the was created when you created the ESB solution project (Ex: DataMapperExampleCompositeApplication) and double-click on the POM file. You view the following screen to select project files into the C-APP.
4. Configuration: Script file that is used to execute the mapping.
5. Input schema: JSON schema which represents the input message format.
6. Output schema: JSON schema which represents the output message format.
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8. 4. You need to refresh the screen to view the registry resource files. Once you refresh the screen, you can see all the artifacts in the workspace.
9. Select the REST API file and the three registry resource files containing the mapping configuration, input schema, and output schema.
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11. 5. Click on the Data Mapper mediator.  You can see 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).
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15. 6. To Export as a C-APP right click on the DataMapperExampleCompositeApplication and select export. Then you can see below dialog box.
    
    Select Composite Application Archive [CAR] and click next.
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17. 7.  Give export destination and click finish.
18. 8. Go to ESB management console (https://localhost:9443/carbon/).
19. 9. Go to carbon Applications in main tab and select Add. Click Choose File and give the C-App which we have already exported and finally click Upload.
    
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Invoking the created REST API

1. 1. Open Postman REST client.
2. 2. Enter the following details to create the client message, enter the content of the XML file as the payload in the text area provided, and click send as below.

1. • URL:  http://<ESB_HOST>:<ESB_PORT>/convertMenu (Ex: http://172.17.0.1:8280/convertMenu)
   • Method: POST
   • Body: raw xml/application
• Message: Enter the input
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5. You view the expected JSON message received as shown below. 
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