Creating a custom service

In Dynamics 365 for Finance and Operations, we still have custom services available to expose the system's functionality to the external world. Microsoft uses the SysOperation framework, where data contracts are decorated with standard attributes, and it automatically serializes and desterilizes data that is shared between two applications. Any service method can be exposed to the external world by using SysEntryPointAttribute and then specifying the service operation under Application Explorer | AOT | Services.

Create Request Class

[DataContractAttribute]
class ansariRequestClass
{
    private str dataAreaId;

    [DataMember("DataAreaId")]
    public str parmDataAreaId(str _value = dataAreaId)
    {
        if (!prmIsDefault(_value))
        {
            dataAreaId = _value;
        }

        return dataAreaId;
    }

}

Create Response Class

[DataContractAttribute]
class ansariResponseClass
{
    private boolean     success;
    private str         errorMessage;
    private str         debugMessage;

    [DataMember("ErrorMessage")]
    public str parmErrorMessage(str _value = errorMessage)
    {
        if (!prmIsDefault(_value))
        {
            errorMessage = _value;
        }

        return errorMessage;
    }

    [DataMember("Success")]
    public Boolean parmSuccess(Boolean _value = success)
    {
        if (!prmIsDefault(_value))
        {
            success = _value;
        }

        return success;
    }

    [DataMember("DebugMessage")]
    public str parmDebugMessage(str _value = debugMessage)
    {
        if (!prmIsDefault(_value))
        {
            debugMessage = _value;
        }

        return debugMessage;
    }

}

Create a Service class

public class ansariServiceClass
{
    public ansariResponseClass create(ansariRequestClass _request)
    {
        var response = new ansariResponseClass();
        changecompany(_request.parmDataAreaId())
        {
            try
            {
                response.parmDebugMessage("Hello World");
                response.parmSuccess(true);
            }
            catch (Exception::CLRError)
            {
                System.Exception interopException = CLRInterop::getLastException();

                response.parmSuccess(false);
                response.parmErrorMessage(interopException.ToString());
            }

            return response;
        }
    }

}

Create a Service with Service Operations

Create Service Group

Test Using Postman tool, Send Request and Get Response

{           
 "_request":
 {
    "DataAreaId":"DAT"
 }            
}

{
    "$id": "1",
    "ErrorMessage": "",
    "Success": true,
    "DebugMessage": "Hello World"
}