Http Server in COBOL

Here’s the translation of the HTTP Server example from Go to COBOL, formatted for Hugo:

In COBOL, creating a basic HTTP server is not as straightforward as in more modern languages. COBOL was not designed for network programming or web services. However, we can demonstrate a conceptual equivalent that shows how to handle incoming requests and send responses.

       IDENTIFICATION DIVISION.
       PROGRAM-ID. HTTP-SERVER.
       ENVIRONMENT DIVISION.
       INPUT-OUTPUT SECTION.
       FILE-CONTROL.
           SELECT CLIENT-SOCKET ASSIGN TO DYNAMIC WS-CLIENT-SOCKET
           ORGANIZATION IS LINE SEQUENTIAL.
       DATA DIVISION.
       FILE SECTION.
       FD CLIENT-SOCKET.
       01 CLIENT-DATA PIC X(1024).
       WORKING-STORAGE SECTION.
       01 WS-CLIENT-SOCKET PIC X(50).
       01 WS-REQUEST    PIC X(1024).
       01 WS-RESPONSE   PIC X(1024).
       
       PROCEDURE DIVISION.
       MAIN-PROCEDURE.
           PERFORM OPEN-SERVER
           PERFORM HANDLE-REQUESTS UNTIL 1 = 2
           PERFORM CLOSE-SERVER
           STOP RUN.

       OPEN-SERVER.
           DISPLAY "Starting server on port 8090"
           * Here we would initialize the server socket
           * This is conceptual as COBOL doesn't have built-in networking

       HANDLE-REQUESTS.
           PERFORM ACCEPT-CONNECTION
           PERFORM PROCESS-REQUEST
           PERFORM SEND-RESPONSE

       ACCEPT-CONNECTION.
           * In a real implementation, this would wait for a client connection
           DISPLAY "Waiting for client connection..."
           ACCEPT WS-CLIENT-SOCKET

       PROCESS-REQUEST.
           * Read the client's request
           READ CLIENT-SOCKET INTO WS-REQUEST
               AT END 
                   DISPLAY "End of client data"
               NOT AT END
                   PERFORM ROUTE-REQUEST

       ROUTE-REQUEST.
           EVALUATE WS-REQUEST
               WHEN "/hello" PERFORM HELLO-HANDLER
               WHEN "/headers" PERFORM HEADERS-HANDLER
               WHEN OTHER PERFORM NOT-FOUND-HANDLER

       HELLO-HANDLER.
           MOVE "hello" TO WS-RESPONSE

       HEADERS-HANDLER.
           * In COBOL, we don't have easy access to HTTP headers
           * This is a simplified version
           MOVE "Content-Type: text/plain" TO WS-RESPONSE

       NOT-FOUND-HANDLER.
           MOVE "404 Not Found" TO WS-RESPONSE

       SEND-RESPONSE.
           * In a real implementation, this would send data back to the client
           DISPLAY "Sending response: " WS-RESPONSE

       CLOSE-SERVER.
           DISPLAY "Closing server"
           * Here we would close the server socket

This COBOL program demonstrates a conceptual HTTP server. It includes the main components of request handling, routing, and response generation. However, it’s important to note that this is a simplified representation and not a fully functional HTTP server.

In COBOL:

We use the FILE-CONTROL and FILE SECTION to handle I/O operations, which in this case represent our network communication.
The WORKING-STORAGE SECTION defines our variables, including the request and response data.
The PROCEDURE DIVISION contains the main logic of our server.

The server runs in an infinite loop (PERFORM HANDLE-REQUESTS UNTIL 1 = 2), accepting connections, processing requests, and sending responses.

To run this COBOL program, you would typically compile it and then execute the resulting program. The exact commands would depend on your COBOL compiler and environment.

Remember, this is a conceptual translation. Implementing a real HTTP server in COBOL would require extensive use of external libraries or system calls, which are beyond the scope of this example.

Exit in COBOL

Execing Processes in COBOL

Learn X By Example

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Http Server in COBOL