(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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Chilkat .NET Framework

Chilkat for .NET Core

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

Chilkat.Rest rest = new Chilkat.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:
Chilkat.Url url = new Chilkat.Url();
url.ParseUrl("http://www.nytimes.com/pages/business/index.html");

bool bAutoReconnect = true;
bool success = rest.Connect(url.Host,url.Port,url.Ssl,bAutoReconnect);

// Send the GET request (This sends the GET request, but does not read the response.)
success = rest.SendReqNoBody("GET",url.Path);
if (success != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// Read the response header.
int responseStatusCode = rest.ReadResponseHeader();
if (responseStatusCode < 0) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

Debug.WriteLine("Response status code = " + Convert.ToString(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
    string errResponse = rest.ReadRespBodyString();
    if (rest.LastMethodSuccess != true) {
        Debug.WriteLine(rest.LastErrorText);
    }
    else {
        Debug.WriteLine(errResponse);
    }

    return;
}

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

// Create a background thread task to read the response body (which feeds
// it to the bodyStream object.)
Chilkat.Task 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.

Chilkat.StringBuilder sbBody = new Chilkat.StringBuilder();
bool exitLoop = false;
while (!exitLoop && (bodyStream.EndOfStream != true)) {

    string bodyText = bodyStream.ReadString();
    if (bodyStream.LastMethodSuccess == true) {
        sbBody.Append(bodyText);
        if (sbBody.Contains("</head>",false)) {
            exitLoop = true;
        }

    }
    else {
        exitLoop = true;
    }

}

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

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

Debug.WriteLine("----");
Debug.WriteLine(sbBody.GetAsString());
Debug.WriteLine("----");
Debug.WriteLine("Successfully received the body up to the desired point.");