Using functions generated with globals

Learn how to use the functions and global records in the stub file to write client applications that use the Web service.

If you have generated stub files for compatibility with your existing GWS client application using GLOBALS, the globals file contains record definitions and the function prototypes obtained from the WSDL.

For example, the information about the Add function from the ws_calculator.inc file, allows you to write code in your own .4gl module that uses this operation as part of your client application.

Using parameters and return values

You call the Add function in your client application, defining variables for the parameters and return values. The input variables for our example are simple integers.

FUNCTION myWScall()  
  DEFINE op1 INTEGER
  DEFINE op2 INTEGER
  DEFINE result INTEGER
  DEFINE wsstatus  INTEGER
  ...
  LET op1 = 6 
  LET op2 = 8
  CALL Add(op1, op2) 
    RETURNING wsstatus, result ...
  DISPLAY result

Using global records

An alternative option is to call the Add_g function instead, using the global records Add and AddResponse directly. If the input variables are complex structures like records or arrays, you are required to use this function.

FUNCTION myWScall()
  DEFINE wsstatus INTEGER
  ...
  LET Add.a = 6
  LET Add.b = 8
  LET wsstatus = Add_g()
  ...
  DISPLAY AddResponse.r

In this case, the status is returned by the function, which has also put the result in the AddResponse global record.

See Tutorial: Writing a Client Application for more information. The demo/WebServices subdirectory of your Genero installation directory contains complete examples of Client Applications.

Using asynchronous calls

If you don't want your application to be blocked when waiting for the response to a request, it is recommended that you first call AddRequest_g; this will send the request using the global Add record to the server. It returns a status of 0 (zero) if everything goes well, -1 in case of error, or -2 if you tried to resend a new request before the previous response was retrieved.

FUNCTION sendMyWScall()
  DEFINE wsstatus INTEGER
  ...
  LET Add.a = 6
  LET Add.b = 8
  LET wsstatus = AddRequest_g()
  IF wstatus <> 0 THEN
    DISPLAY "ERROR :", wsError.code
  END IF
  ...

You can then call AddResponse_g to retrieve the response in the AddResponse global record of the previous request. If the returned status is 0 (zero), the response was successfully received; -1 means that there was an error, and -2 means that the response was not yet received and that the function needs to be called later.

FUNCTION retrieveMyWScall()
  DEFINE wsstatus INTEGER
  ...
  LET wsstatus = AddResponse_g()  
  CASE wstatus
    WHEN -2
      DISPLAY "No response available, try later"
    WHEN 0
      DISPLAY "Response is :",AddResponse.r  
    OTHERWISE
      DISPLAY "ERROR :", wsError.code
  END CASE
  ...

You can mix the asynchronous call with the synchronous one as they are using two different requests. In other words, you can perform an asynchronous request with AddRequest_g, then a synchronous call with Add_g, and then retrieve the response of the previous asynchronous request with AddResponse_g.

Important:

In development mode, a single BDL Web Service server can only handle one request at a time, and several asynchronous requests in a row without retrieving the corresponding response will lead to a deadlock. To support several asynchronous requests in a row, it is recommended that you are in deployment mode with a GAS as the front-end.