(C) HTTP GET -- Read Response from Stream

Demonstrates how to send an HTTP GET for a web page, and then read the response from a Stream. The purpose is to fulfill a situation such as the following: "I have a URL and just want the <head> </head> portion of the HTML. This would avoid having to download a potentially enormous web page just to get at header information, such as the <styles>."

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#include <C_CkRest.h>
#include <C_CkUrl.h>
#include <C_CkStream.h>
#include <C_CkTask.h>
#include <C_CkStringBuilder.h>

void ChilkatSample(void)
    {
    HCkRest rest;
    HCkUrl url;
    BOOL bAutoReconnect;
    BOOL success;
    int responseStatusCode;
    const char *errResponse;
    HCkStream bodyStream;
    HCkTask readResponseBodyTask;
    HCkStringBuilder sbBody;
    BOOL exitLoop;
    const char *bodyText;
    int maxWaitMs;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    rest = CkRest_Create();

    // In this example, we'll get the web page at http://www.nytimes.com/pages/business/index.html
    // The domain is "www.nytimes.com", and the path is "/pages/business/index.html"

    // If we have only the full URL to begin with, it can be loaded into the Chilkat URL object to
    // access the parts:
    url = CkUrl_Create();
    CkUrl_ParseUrl(url,"http://www.nytimes.com/pages/business/index.html");

    bAutoReconnect = TRUE;
    success = CkRest_Connect(rest,CkUrl_host(url),CkUrl_getPort(url),CkUrl_getSsl(url),bAutoReconnect);

    // Send the GET request (This sends the GET request, but does not read the response.)
    success = CkRest_SendReqNoBody(rest,"GET",CkUrl_path(url));
    if (success != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkRest_Dispose(rest);
        CkUrl_Dispose(url);
        return;
    }

    // Read the response header.
    responseStatusCode = CkRest_ReadResponseHeader(rest);
    if (responseStatusCode < 0) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkRest_Dispose(rest);
        CkUrl_Dispose(url);
        return;
    }

    printf("Response status code = %d\n",responseStatusCode);

    // We expect a 200 response status.
    if (responseStatusCode != 200) {

        // If the response status code is not 200, we could check for a redirect status code and 
        // then follow it, read the entire response (as shown here), or just call rest.Disconnect
        errResponse = CkRest_readRespBodyString(rest);
        if (CkRest_getLastMethodSuccess(rest) != TRUE) {
            printf("%s\n",CkRest_lastErrorText(rest));
        }
        else {
            printf("%s\n",errResponse);
        }

        CkRest_Dispose(rest);
        CkUrl_Dispose(url);
        return;
    }

    bodyStream = CkStream_Create();
    // Set a 10 second read timeout for the stream. 
    // (Give up if no data arrives within 10 seconds after calling a read method.)
    CkStream_putReadTimeoutMs(bodyStream,10000);

    // Create a background thread task to read the response body (which feeds
    // it to the bodyStream object.)
    readResponseBodyTask = CkRest_ReadRespBodyStreamAsync(rest,bodyStream,TRUE);

    // Start the task. 
    success = CkTask_Run(readResponseBodyTask);

    // Read the HTTP response body until the "</head>" is seen, or until
    // the end-of-stream is reached.

    sbBody = CkStringBuilder_Create();
    exitLoop = FALSE;
    while (!exitLoop && (CkStream_getEndOfStream(bodyStream) != TRUE)) {

        bodyText = CkStream_readString(bodyStream);
        if (CkStream_getLastMethodSuccess(bodyStream) == TRUE) {
            CkStringBuilder_Append(sbBody,bodyText);
            if (CkStringBuilder_Contains(sbBody,"</head>",FALSE)) {
                exitLoop = TRUE;
            }

        }
        else {
            exitLoop = TRUE;
        }

    }

    // Cancel the remainder of the task...
    CkTask_Cancel(readResponseBodyTask);

    CkTask_Dispose(readResponseBodyTask);

    // Ensure we're disconnected from the server.
    maxWaitMs = 50;
    CkRest_Disconnect(rest,maxWaitMs);

    printf("----\n");
    printf("%s\n",CkStringBuilder_getAsString(sbBody));
    printf("----\n");
    printf("Successfully received the body up to the desired point.\n");


    CkRest_Dispose(rest);
    CkUrl_Dispose(url);
    CkStream_Dispose(bodyStream);
    CkStringBuilder_Dispose(sbBody);

    }