Exposing Apex Classes as REST Web Services

Steps to expose your Apex class and methods to external applications:

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Define the Apex class with the @RestResource(urlMapping='/yourUrl') annotation

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Define Apex methods with the following annotation depending on the operation you want to provide:

• @HttpDelete eg,@HttpDelete global static Account doDelete(){}

• @HttpGet - should have no parameters. eg,@HttpGet global static Account doGet(){} Note: should have no parameters. This is because GET and DELETE requests have no request body, so there's nothing to deserialize.
  

• @HttpPatch

• @HttpPost

• @HttpPut

Apex REST Methods:

Apex REST supports two formats for representations of resources:

JSON and XML.

JSON representations are passed by default in the body of a request or response, and the format is indicated by the Content-Type property in the HTTP header.

You can retrieve the body as a Blob from the HttpRequest object if there are no parameters to the Apex method.

Eg:

@HttpPost

global static String createCase() {

RestRequest req = RestContext.request;

RestResponse res = RestContext.response;

try{

Blob reqBody = req.requestBody;

System.debug('request body ' + reqBody.toString());

}

catch(Exception e){

return e.getStackTraceString();

}

return 'success';

}

If the Apex method has a non-void return type, the resource representation is serialized into the response body.

These return and parameter types are allowed:

• Apex primitives (excluding sObject and Blob).

• sObjects

• Lists or maps of Apex primitives or sObjects (only maps with String keys are supported).

• User-defined types that contain member variables of the types listed above.

Note: Single Apex class annotated with @RestResource can't have multiple methods annotated with the same HTTP request method. For example, the same class can't have two methods annotated with @HttpGet.

RestRequest and RestResponse objects are available by default in your Apex methods through the static RestContext object. This example shows how to access these objects through RestContext:

RestRequest req = RestContext.request;

RestResponse res = RestContext.response;

method with parameters - POST or PUT, Apex REST attempts to deserialize the data into those parameters and the data won't be deserialized into the RestRequest.requestBody property.

An Apex method with a non-void return type will have the return value serialized into RestResponse.responseBody.

Governor Limits:

Description Synchronous Limit Asynchronous Limit

Total number of callouts

(HTTP requests or web

services calls) in a tnx 100

Maximum cumulative

timeout for all callouts

(HTTP requests or

Web services calls) in

a transaction 120 seconds

Maximum size of callout

request or response (HTTP

request or Web services

call) 16 MB 12 MB

To invoke Apex REST in Mule:

https://help.mulesoft.com/s/article/How-to-invoke-APEX-REST-and-SOAP-method-using-Salesforce-Connector