(Xojo Plugin) 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 Xojo Plugin Download

Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

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

Dim rest As 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:
Dim url As New Chilkat.Url
Dim success As Boolean
success = url.ParseUrl("http://www.nytimes.com/pages/business/index.html")

Dim bAutoReconnect As Boolean
bAutoReconnect = True
Dim success As Boolean
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) Then
    System.DebugLog(rest.LastErrorText)
    Return
End If

// Read the response header.
Dim responseStatusCode As Int32
responseStatusCode = rest.ReadResponseHeader()
If (responseStatusCode < 0) Then
    System.DebugLog(rest.LastErrorText)
    Return
End If

System.DebugLog("Response status code = " + Str(responseStatusCode))

// We expect a 200 response status.
If (responseStatusCode <> 200) Then

    // 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
    Dim errResponse As String
    errResponse = rest.ReadRespBodyString()
    If (rest.LastMethodSuccess <> True) Then
        System.DebugLog(rest.LastErrorText)
    Else
        System.DebugLog(errResponse)
    End If

    Return
End If

Dim bodyStream As 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.)
Dim readResponseBodyTask As 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.

Dim sbBody As New Chilkat.StringBuilder
Dim exitLoop As Boolean
exitLoop = False
While Not exitLoop And (bodyStream.EndOfStream <> True)

    Dim bodyText As String
    bodyText = bodyStream.ReadString()
    If (bodyStream.LastMethodSuccess = True) Then
        success = sbBody.Append(bodyText)
        If (sbBody.Contains("</head>",False)) Then
            exitLoop = True
        End If

    Else
        exitLoop = True
    End If

Wend

// Cancel the remainder of the task...
success = readResponseBodyTask.Cancel()

// Ensure we're disconnected from the server.
Dim maxWaitMs As Int32
maxWaitMs = 50
success = rest.Disconnect(maxWaitMs)

System.DebugLog("----")
System.DebugLog(sbBody.GetAsString())
System.DebugLog("----")
System.DebugLog("Successfully received the body up to the desired point.")