(Go) REST Read Response with Stream API

Demonstrates how to make a REST call that returns a binary body, and to receive the body through a stream API.

Chilkat Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

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

    rest := chilkat.NewRest()

    // Connect to the Amazon AWS REST server.
    bTls := true
    port := 443
    bAutoReconnect := true
    success := rest.Connect("s3.amazonaws.com",port,bTls,bAutoReconnect)

    // ----------------------------------------------------------------------------
    // Important: For buckets created in regions outside us-east-1,
    // there are three important changes that need to be made.
    // See Working with S3 Buckets in Non-us-east-1 Regions for the details.
    // ----------------------------------------------------------------------------

    // Provide AWS credentials for the REST call.
    authAws := chilkat.NewAuthAws()
    authAws.SetAccessKey("AWS_ACCESS_KEY")
    authAws.SetSecretKey("AWS_SECRET_KEY")
    authAws.SetServiceName("s3")
    success = rest.SetAuthAws(authAws)

    // Set the bucket name via the HOST header.
    // In this case, the bucket name is "chilkat100".
    rest.SetHost("chilkat100.s3.amazonaws.com")

    // Send the request to download the JPG.
    success = rest.SendReqNoBody("GET","/starfish.jpg")
    if success != true {
        fmt.Println(rest.LastErrorText())
        rest.DisposeRest()
        authAws.DisposeAuthAws()
        return
    }

    // Read the response header.
    responseStatusCode := rest.ReadResponseHeader()
    if responseStatusCode < 0 {
        fmt.Println(rest.LastErrorText())
        rest.DisposeRest()
        authAws.DisposeAuthAws()
        return
    }

    fmt.Println("Response status code = ", responseStatusCode)

    // We expect a 200 response status if the JPG data is coming.
    // Otherwise, we'll get a string response body with an error message(or no response body).
    if responseStatusCode != 200 {
        errResponse := rest.ReadRespBodyString()
        if rest.LastMethodSuccess() != true {
            fmt.Println(rest.LastErrorText())
        } else {
            fmt.Println(*errResponse)
        }

        rest.DisposeRest()
        authAws.DisposeAuthAws()
        return
    }

    bodyStream := chilkat.NewStream()
    // Set a 10 second read timeout for the stream. 
    // (Give up if no data arrives within 10 seconds after calling a read method.)
    bodyStream.SetReadTimeoutMs(10000)

    // Create a background thread task to read the response body (which feeds
    // it to the bodyStream object.)
    c := make(chan *chilkat.Task)
    go rest.ReadRespBodyStreamAsync(bodyStream,true,c)
    readResponseBodyTask := <-c

    // Start the task. 

    // The application can now read the bodyStream...
    for (bodyStream.EndOfStream() != true) {

        // Read the next chunk of bytes (whatever is immediately available,
        // or wait for more data (up to 10 seconds because we set the stream's ReadTimeoutMs property)
        nextChunk := bodyStream.ReadBytes()
        if bodyStream.LastMethodSuccess() != true {
            fmt.Println("Failed to receive more response data.")
            // Make sure the background task is aborted/cancelled.
            success = readResponseBodyTask.Cancel()
            readResponseBodyTask.DisposeTask()
            rest.DisposeRest()
            authAws.DisposeAuthAws()
            bodyStream.DisposeStream()
            readResponseBodyTask.DisposeTask()
            return
        }

        // OK.. the app has the next chunk of the body, and may do whatever it wishes with it...
    }

    readResponseBodyTask.DisposeTask()

    fmt.Println("Successfully received the entire response body.")

    rest.DisposeRest()
    authAws.DisposeAuthAws()
    bodyStream.DisposeStream()
    readResponseBodyTask.DisposeTask()