Unicode 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>."

Chilkat Unicode C++ Downloads

Download Chilkat for Unicode C++

Unicode C++

#include <CkRestW.h>
#include <CkUrlW.h>
#include <CkStreamW.h>
#include <CkTaskW.h>
#include <CkStringBuilderW.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    CkRestW rest;

    // 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:
    CkUrlW url;
    url.ParseUrl(L"http://www.nytimes.com/pages/business/index.html");

    bool bAutoReconnect = true;
    success = rest.Connect(url.host(),url.get_Port(),url.get_Ssl(),bAutoReconnect);

    // Send the GET request (This sends the GET request, but does not read the response.)
    success = rest.SendReqNoBody(L"GET",url.path());
    if (success != true) {
        wprintf(L"%s\n",rest.lastErrorText());
        return;
    }

    // Read the response header.
    int responseStatusCode = rest.ReadResponseHeader();
    if (responseStatusCode < 0) {
        wprintf(L"%s\n",rest.lastErrorText());
        return;
    }

    wprintf(L"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
        const wchar_t *errResponse = rest.readRespBodyString();
        if (rest.get_LastMethodSuccess() != true) {
            wprintf(L"%s\n",rest.lastErrorText());
        }
        else {
            wprintf(L"%s\n",errResponse);
        }

        return;
    }

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

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

    // Start the task. 
    success = readResponseBodyTask->Run();

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

    CkStringBuilderW sbBody;
    bool exitLoop = false;
    while (!exitLoop && (bodyStream.get_EndOfStream() != true)) {

        const wchar_t *bodyText = bodyStream.readString();
        if (bodyStream.get_LastMethodSuccess() == true) {
            sbBody.Append(bodyText);
            if (sbBody.Contains(L"</head>",false)) {
                exitLoop = true;
            }

        }
        else {
            exitLoop = true;
        }

    }

    // Cancel the remainder of the task...
    readResponseBodyTask->Cancel();

    delete readResponseBodyTask;

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

    wprintf(L"----\n");
    wprintf(L"%s\n",sbBody.getAsString());
    wprintf(L"----\n");
    wprintf(L"Successfully received the body up to the desired point.\n");
    }