com.WebServiceEngine.GetHTTPServiceRequest

Get a handle for an incoming HTTP service request.

Syntax

com.WebServiceEngine.GetHTTPServiceRequest(
   timeout INTEGER)
  RETURNS com.HttpServiceRequest
  1. timeout defines the timeout in seconds.

It returns a com.HttpServiceRequest object.

Usage

The com.WebServiceEngine.GetHTTPServiceRequest() class method returns a com.HttpServiceRequest object to handle an incoming HTTP request, or NULL if no request arrives during the specified timeout.
  • timeout seconds to wait for a request. Use -1 for infinite wait. Returns NULL on timeout.

  • In case of error, the method throws an exception and sets the status variable. Depending on the error, a human-readable description of the problem is available in the sqlca.sqlerrm register. See Error handling in GWS calls (status).

    Even if the exception is trapped, the GWS HTTP server is not in a valid state anymore, and you must close the application properly before exiting the program.
    Note:

    This is not an issue in production environments as the Genero Application Server (GAS) and GWSProxy will detect the ended DVM, return an HTTP error code to the client app, and any new request will start a new DVM in a clean state via GWS proxy and the pool configuration.

  • Any new call to this function will raise an error until the previous HTTP request is handled by sending a response back to the client, or destroyed.
Error conditions (summary)
  • -15565: Invalid/unsupported HTTP request
    • Thrown for invalid or unsupported HTTP methods. Supported methods are GET, PUT, POST, HEAD, and DELETE.
  • -15575: GAS disconnected the Web Services program
    • Thrown when the Genero Application Server disconnects the WS program.
  • -15552: URL charset conversion failure
    • Thrown when the server cannot convert UTF-8 URLs to the runtime (fglrun) locale charset.
    • Recommendation: run the Web Services server program in UTF-8.

Example

This example demonstrates using com.WebServiceEngine.getHTTPServiceRequest(10) to handle incoming requests. In the WHILE loop, if no request arrives within 10 seconds the call returns NULL and the current time is output. When a request arrives (for example, curl localhost:8090/service_request), it replies with 200 and includes the request URL. The loop is wrapped in a TRY/CATCH to handle disconnects, using the status variable to report errors (status == -15575).

Key points:

  • getHTTPServiceRequest(10): waits up to 10 seconds (use -1 to wait indefinitely).
  • req IS NULL: timeout heartbeat (prints time).
  • req.sendTextResponse(..., req.getUrl()): sends 200 response including the request URL.

# service_request.4gl
IMPORT com

MAIN
  DEFINE req com.HttpServiceRequest
  DISPLAY "Server started"
  CALL com.WebServiceEngine.Start()
  TRY
    WHILE TRUE
      LET req = com.WebServiceEngine.getHTTPServiceRequest(10)
      IF req IS NULL THEN
        DISPLAY "HTTP request timeout...: ", CURRENT YEAR TO FRACTION
      ELSE
         CALL req.sendTextResponse(200,NULL,SFMT("It works (%1)", req.getUrl()))
      END IF
    END WHILE
    CATCH
      IF status == -15575 THEN
        DISPLAY "Disconnected : ",sqlca.sqlerrm
      ELSE
        DISPLAY SFMT("ERROR : %1 - %2",status,sqlca.sqlerrm)
      END IF
  END TRY
END MAIN