Convert a JSON Message to SOAP and SOAP to JSON

This tutorial uses the WSO2 API Manager Tooling Plug-in and the PhoneVerification API created in Create and Publish an API .

The API Gateway has a default mediation flow for the API invocation requests that it receives. You can extend this default mediation flow to do additional custom mediation for the messages in the API Gateway. An extension is provided as a synapse mediation sequence. You can design sequences using a tool such as the WSO2 API Manager Tooling Plug-in and then store the sequence in the Gateway's registry.

Let's see how to convert message types using custom sequences. In this tutorial, we convert a JSON payload to SOAP before sending it to a SOAP backend. Then we receive the response in SOAP and convert it back to JSON.

Log in to the API Publisher and click the PhoneVerification API.
Click the Edit icon to go to its edit mode.
Create the following resource and add it to the API.
After the resource is added, expand it and edit the parameter as follows. This parameter is used to pass the payload to the backend.
Next, let's write a sequence to convert the JSON payload to a SOAP request. We do this because the backend accepts SOAP requests.
Navigate to the Implement page and change the endpoint of the API to http://ws.cdyne.com/phoneverify/phoneverify.asmx?WSDL. Once the edits are done, click Save.
Download and install the WSO2 API Manager Tooling Plug-in if you have not done so already. Open Eclipse by double clicking the Eclipse.app file inside the downloaded folder.
Click Window > Open Perspective > Other to open the Eclipse perspective selection window. Alternatively, click the Open Perspective icon shown below at the top right corner.
On the dialog box that appears, click WSO2 APIManager and click OK.
On the APIM perspective, click the Login icon as shown below.
On the dialog box that appears, enter the URL, username and password of the Publisher server.
On the tree view that appears, expand the folder structure of the existing API.
Right-click on the In sequence folder and click Create to create a new In sequence.
Name the sequence JSONtoSOAP.
Your sequence now appears on the APIM perspective. From under the Mediators section, drag and drop a PayloadFactory mediator to your sequence and give the following values to the mediator.
Similarly, add a Property mediator to the same sequence and give the following values to the property mediator. This mediator changes the payload type of the outgoing message to soap+xml. More information about the Property mediator can be found here.
Save the sequence, which is in XML format (e.g., JSONtoSOAP.xml). This will be the In sequence for your API. Next, create an Out sequence.
Right-click on the Out sequence folder and click Create to create a new Out sequence.
Name the sequence SOAPtoJSON.
Add a Log mediator to the sequence and give the following values. Note that the property value provided is a string literal.
Similarly, add a PayLoadFactory mediator with the following values. This mediator in the out sequence is used to transform the SOAP message content returned from the backend into JSON.
Finally, add a Property mediator with the following values. This mediator changes the payload type of the incoming message to json.
Save the sequence, which is in XML format (e.g., SOAPtoJSON.xml). This will be the Out sequence for your API.
Click the Push all changes to the server icon shown below to commit your changes to the Publisher server.
Log back in to the API Publisher, click the Edit link associated with the API and navigate to the Implement tab. Select the Enable Message Mediation check box and engage the In and Out sequences that you created earlier.
Save the API.
You have created an API, a resource to access the SOAP backend and engaged sequences to the request and response paths to convert the message format from JSON to SOAP and back to JSON. Let's subscribe to the API and invoke it.
Log in to the API Store and subscribe to the API and create an access token if you have not done so already.
Go to the API Console tab and expand the POST method.
Give the payload in the body parameter in JSON format and click Try it out. Here's a sample JSON payload: {"request":{"PhoneNumber":"18006785432","LicenseKey":"0"}}
Note that you get a JSON response to the JSON request whereas the backend accepts SOAP messages. The request and response are converted by the sequences that you engaged.

In this tutorial, you converted a message from JSON to SOAP and back to JSON using In and Out sequences.