如何在 Progress/OpenEdge ABL 中执行 HTTP GET 和 POST？

Question

Progress 文档在 SOAP 上花费了大量的精力，但我很难找到带有 Progress ABL 的简单 HTTP GET/POST 示例。

如何从 URL 获取和发布字符串？

URL 可以是 https:// 吗？

Progress 可以提供 HTTP Basic 或 HTTP Digest 身份验证吗？

Answer 1

对于这个问题的未来旁观者：

Openedge 现在（我相信从 11.5.1 开始）已经内置了对调用基于 REST 的 Web 服务的支持。它们包含在提供的 .pl 存档中，默认情况下该存档不在您的 PROPATH 中，因此需要首先处理（或者可以将存档移动到“更好的位置”）。

propath 可以通过多种方式设置，初始化文件、注册表、编程方式等。这就是在 ABL 中完成的方式（如果这样做，则必须为每个新会话重复）。

PROPATH = PROPATH + ",c:\pathtoprogress\OpenEdge\gui\OpenEdge.Net.pl".

“tty”目录中还有一个版本，以及“src”目录中包含源代码的存档。

这是一个非常基本的示例：

USING OpenEdge.Net.HTTP.IHttpRequest.
USING OpenEdge.Net.HTTP.IHttpResponse.
USING OpenEdge.Net.HTTP.ClientBuilder.
USING OpenEdge.Net.HTTP.RequestBuilder. 

DEFINE VARIABLE oRequest  AS IHttpRequest NO-UNDO.
DEFINE VARIABLE oResponse AS IHttpResponse NO-UNDO.

oRequest = RequestBuilder:Get('http://stackoverflow.com/'):Request. 

oResponse = ClientBuilder:Build():Client:Execute(oRequest).

MESSAGE
    oResponse:StatusCode SKIP   
    oResponse:StatusReason SKIP
    VIEW-AS ALERT-BOX.

11.6 的文档可以在此处找到。

Answer 2

Openedge 内置了用于处理 SOAP 服务的语句，但没有用于 GET/POST 的简单语句。然而，它确实具有一种读/写特定套接字的机制。因此，您可以使用它来构建 HTTP post 例程，或者就此而言，构建一个处理任何其他基于套接字的协议的例程。

有一个例程 - http.p - 将为您执行 GET 操作。如果没有别的事情的话，会让你看看套接字编程是如何工作的。您应该能够很容易地修改它来执行简单的 POST，但使用 SSL 或进入身份验证可能需要相当多的工作。在这种情况下，直接退出 CURL 可能会更容易。

http.p 曾经可以从 freeframework.org 获得，但我刚刚检查过，该域已过期，所以我发布了下面的代码。

/*-----------------------------------------------------------------------*
  File........: http.p
  Version.....: 1.1
  Description : Makes a "Get" request from an HTTP server
  Input Param : pHost = host name (without the "http://")
                pPort = port number (usually 80)
                pURL =  begin with the first slash after the domain name.

  Output Param: pResult = 0 or 1 (character)
                pResponse = http headers returned
                pContent = the document returned.
  Author......: S.E. Southwell, Mario Paranhos -  United Systems, Inc. (770) 449-9696
  Created.....: 12/13/2000
  Notes.......: Will not work with HTTPS.
  Usage:
        define var v-result as char no-undo.
        define var v-response as char no-undo.
        define var v-content as char no-undo.
        {&out} "Hello" skip.
        put stream webstream control null(0).
        run proc/http.p("www.whosplayin.com","80","/",output v-result,output v-response,output v-content).
        {&out} v-result "<hr>" skip
        html-encode(v-response) "<hr>" skip
        html-encode(v-content) "<hr>" skip
        .

  Last Modified: 10/20/01 - SES - Fixed to work in batch mode, or within a UDF.
--------------------------------------------------------------------------*/



&SCOPED-DEFINE HTTP-NEWLINE CHR(13) + CHR(10)
&SCOPED-DEFINE RESPONSE-TIMEOUT 45

DEFINE INPUT PARAMETER pHOST        AS CHAR NO-UNDO.
DEFINE INPUT PARAMETER pPORT        AS CHAR NO-UNDO.
DEFINE INPUT PARAMETER pURL         AS CHAR NO-UNDO.
DEFINE OUTPUT PARAMETER pRESULT     AS CHAR NO-UNDO.
DEFINE OUTPUT PARAMETER pRESPONSE   AS CHAR NO-UNDO.
DEFINE OUTPUT PARAMETER pContent    AS CHAR NO-UNDO.


DEFINE VARIABLE requestString       AS CHAR   NO-UNDO.
DEFINE VARIABLE vSocket             AS HANDLE NO-UNDO.   
DEFINE VARIABLE vBuffer             AS MEMPTR NO-UNDO.
DEFINE VARIABLE vloop               AS LOGICAL NO-UNDO.
DEFINE VARIABLE vPackets            AS INTEGER NO-UNDO.
DEFINE VARIABLE wStatus             AS LOGICAL NO-UNDO.

ASSIGN requestString = "GET " + pURL + " HTTP/1.0" + {&HTTP-NEWLINE} +
          "Accept: */*" + {&HTTP-NEWLINE} + 
          "Host: " + phost + {&HTTP-NEWLINE} + 
          /*"Connection: Keep-Alive" + {&HTTP-NEWLINE} + */
          {&HTTP-NEWLINE}.

/*OPEN THE SOCKET*/
CREATE SOCKET vSocket.
vSocket:SET-READ-RESPONSE-PROCEDURE ("readHandler",THIS-PROCEDURE).
ASSIGN wstatus = vSocket:CONNECT("-H " + phost + " -S " + pport) NO-ERROR.

/*Now make sure the socket is open*/
IF wstatus = NO THEN DO:
    pResult = "0:No Socket".
    DELETE OBJECT vSocket.
    RETURN.
END.

/*Got socket - Now make HTTP request*/

SET-SIZE(vBuffer) = LENGTH(requestString) + 1.
PUT-STRING(vBuffer,1) = requestString.
vSocket:WRITE(vBuffer, 1, LENGTH(requestString)).
SET-SIZE(vBuffer) = 0.

/*Wait for a response*/
ASSIGN vloop = TRUE.  /*Turns off automatically when request is done*/
DEFINE VAR vstarttime AS INTEGER.
ASSIGN vstarttime = etime.

WAITLOOP: DO WHILE vloop:
    PROCESS EVENTS.
    PAUSE 1.
    /* Build in timer in case sending is never set to NO 
       this will terminate the program after 60 seconds
       start-Etime will be reset by WriteData each time there
       is activity on the socket to allow for long transmissions */
    IF vstarttime + ({&RESPONSE-TIMEOUT} * 1000) < ETIME 
     THEN DO:
        MESSAGE "timed out at " + string(etime - vstarttime) + " msec".
        vSocket:DISCONNECT().
        ASSIGN pResult = "0:Failure".
        RETURN.
    END. /*No Response, or timed out*/
END.



/*At this point, pResponse should be populated with the result (up to 32K)*/


vSocket:DISCONNECT().

DELETE OBJECT vSocket.
/*All Done!*/
ASSIGN pResult = "1:Success".
ASSIGN 
 pContent = SUBSTRING(pResponse,INDEX(pResponse,{&HTTP-NEWLINE} + {&HTTP-NEWLINE}),-1)
 .
ASSIGN
 pResponse = SUBSTRING(pResponse,1,INDEX(pResponse,{&HTTP-NEWLINE} + {&HTTP-NEWLINE}))
.

RETURN.


/*Handle the response from the webserver*/
PROCEDURE readHandler:
    DEFINE VARIABLE bytesAvail  AS INTEGER  NO-UNDO.
    DEFINE VARIABLE b           AS MEMPTR   NO-UNDO.
    DEFINE VARIABLE lastBytes   AS INTEGER  NO-UNDO.

    IF vSocket:connected() THEN ASSIGN bytesAvail = vSocket:GET-BYTES-AVAILABLE().

    IF bytesAvail = 0 THEN DO: /*All Done*/
      ASSIGN vloop = FALSE.
      RETURN.
    END.


    /*OK, there's something on the wire... Read it in*/    
    SET-SIZE(b) = bytesAvail + 1.
    vSocket:READ(b, 1, bytesAvail, 1).
    ASSIGN pResponse = pResponse + GET-STRING(b,1).
    SET-SIZE(b) = 0.
END PROCEDURE. /*readHandler*/

Answer 3

Progress Kbase ID：20011：“使用 4GL 套接字通过 HTTP 访问网站的示例代码”也是一个很好的通用示例。

Answer 4

我建议使用上面 Gordon Roberertson 的代码示例，因为 Progress KB 文章中的“WAIT-FOR”被替换为循环。因此，如果出现任何问题，程序将在超时后终止。

请注意，更改 requestString 中的任何内容都可能导致超时。但是，如果您需要登录网络服务器，则可以添加用户代理：

ASSIGN requestString = "GET " + Path + " HTTP/1.0" + {&HTTP-NEWLINE}
               + "Accept: */*" + {&HTTP-NEWLINE}
               + "User-Agent: " + "User Agent String" + {&HTTP-NEWLINE}
               + "Host: " + Host + {&HTTP-NEWLINE}
               + {&HTTP-NEWLINE}.

感谢 Gordon 提供的代码示例。