DataFlex

Send a Staged REST Request with a Streamed Body

Demonstrates Rest.SendReqStreamBody, which sends a request whose body is read from a Stream, then reads the response in separate steps.

The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background. The staged request model separates sending from reading: a SendReq method transmits the request, ReadResponseHeader reads the status line and headers, and a ReadResp method reads the body. This gives fine control over large or streamed messages compared with the single-call full-request methods.

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DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoRest
    Boolean iBTls
    Boolean iBAutoReconnect
    Variant vBodyStream
    Handle hoBodyStream
    Integer iStatusCode
    String sResponseBody
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    Get Create (RefClass(cComChilkatRest)) To hoRest
    If (Not(IsComObjectCreated(hoRest))) Begin
        Send CreateComObject of hoRest
    End
    Move True To iBTls
    Move True To iBAutoReconnect
    Get ComConnect Of hoRest "example.com" 443 iBTls iBAutoReconnect To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  The file paths are relative to the application's current working directory.  Absolute paths
    //  may also be used.  Supply the paths appropriate to your own environment.

    //  The request body is read from a Stream whose source is a local file.
    Get Create (RefClass(cComChilkatStream)) To hoBodyStream
    If (Not(IsComObjectCreated(hoBodyStream))) Begin
        Send CreateComObject of hoBodyStream
    End
    Set ComSourceFile Of hoBodyStream To "qa_data/upload.json"

    Get ComAddHeader Of hoRest "Content-Type" "application/json" To iSuccess

    //  Send the request, reading the body from the stream.  The 3rd argument is the Stream.
    Get pvComObject of hoBodyStream to vBodyStream
    Get ComSendReqStreamBody Of hoRest "POST" "/api/upload" vBodyStream To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  After sending, read the response status line and header fields.  The return value is the HTTP
    //  status code, or -1 if no response was received.
    Get ComReadResponseHeader Of hoRest To iStatusCode
    If (iStatusCode < 0) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Response status code: " iStatusCode

    //  Read the response body as text.
    Get ComReadRespBodyString Of hoRest To sResponseBody
    Get ComLastMethodSuccess Of hoRest To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln sResponseBody


End_Procedure