Node.js

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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Node.js

NODEJS_PRELUDE

function chilkatExample() {

    var success = false;

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

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

    var bAutoReconnect = true;
    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) {
        console.log(rest.LastErrorText);
        return;
    }

    //  Read the response header.
    var responseStatusCode = rest.ReadResponseHeader();
    if (responseStatusCode < 0) {
        console.log(rest.LastErrorText);
        return;
    }

    console.log("Response status code = " + 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
        var errResponse = rest.ReadRespBodyString();
        if (rest.LastMethodSuccess !== true) {
            console.log(rest.LastErrorText);
        }
        else {
            console.log(errResponse);
        }

        return;
    }

    var 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.)
    // readResponseBodyTask: Task
    var 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.

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

        var 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.
    var maxWaitMs = 50;
    rest.Disconnect(maxWaitMs);

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

}

chilkatExample();