Web Api Is not returning after action is successfully invoked.

Question

0.00/5 (No votes)

See more:

Web Api is not returning after action is successfully invoked.

Here is the action I am trying to Invoke

C#

   public class TestController : ApiController{
        // GET api/test
        public string[] Get()
        {
            string[] names = new string[3] {"Matt", "Joanne", "Robert"};
            using (SpeechSynthesizer ss = new SpeechSynthesizer())
            {
                ss.Rate = -2;
                var word = "Test This Two";

                var filePath = HttpContext.Current.Request.MapPath("~/Content/sounds/" + word + ".wav");
                ss.SetOutputToWaveFile(filePath);
                ss.Speak(word);
                ss.SetOutputToNull();
                ss.Dispose();
            }
            return names;
        }
}

From the browsers perspective, the page continues to cycle, waiting for a response, after this method has successfully returned the string array.

Does anyone know why this method is not returning results to the browser? Is it possible that an asynchronous thread is still running? I have debugged this method and it is invoked and returns successfully.

Cheers,
robNo.

Update

This is a test, and I am expecting the results to contain the static array. All I am trying to accomplish is making sure I can use the System.Speech assembly on my hosting environment, but first I am trying to make it work locally.

Update 2

I commented out the using statement and I successfully received the static array as xml in the browser. Therefore, its the System.Speech code that is causing the problems

I did finally received an error message on the browser: An asynchronous module or handler completed while an asynchronous operation was still pending.

This error is odd to me, because according to what I can gathered from MSDN, the SpeechSynthesizer methods I am using are synchronous, which is what I want.

Posted 30-Apr-13 8:28am

RobNO

Updated 30-Apr-13 9:23am

v5

Add a Solution

Comments

Richard C Bishop 30-Apr-13 14:39pm

How are you capturing the response?

RobNO 30-Apr-13 14:43pm

I am simply using the direct url in the browser (e.g. http://localhost:61303/api/test), but unfortunately I never receive my response, which is why I am confused because when I debug this method it returns successfully.

Richard C Bishop 30-Apr-13 14:47pm

If you do not have anything on your page to capture the response, you will never get it. Are you using SOAP to communicate with the API and using the response from that?

RobNO 30-Apr-13 14:50pm

I am using Asp.net Web Api which is based around HTTP. I should be seeing the results (the static string array) in XML on the browser.

db7uk 30-Apr-13 14:42pm

I doubt it. not sure that calling the speech synthesizer is right also... are you expecting this to be heard on the website?

Anyway, what does the response show you in fiddler? what happens if you just return a string value "test" without the array. are you wanting the array to appear or the sound?

RobNO 30-Apr-13 14:46pm

This is a test, and I am expecting the results to contain the static array. All I am trying to accomplish is making sure I can use the System.Speech assembly on my hosting environment, but first I am trying to make it work locally.

Keith Barrow 30-Apr-13 14:44pm

Have you examined the response in Fiddler or a similar tool?

RobNO 30-Apr-13 14:46pm

Yes, the response is always pending.

Keith Barrow 30-Apr-13 14:49pm

Got to check the easy stuff first! I assume it works if the using block is commented?

RobNO 30-Apr-13 14:53pm

Yes, this code works without using the Using syntactical sugar

Keith Barrow 30-Apr-13 14:56pm

Can't check this right now, but I *think* you are getting an error with ss.Dispose(); which is redundant.
The using block disposes the object for you.

RobNO 30-Apr-13 14:58pm

Tried that and it didnt help. However I did comment all of the using statment and I did successfully receive the static array. My browser finally returned an error message: An asynchronous module or handler completed while an asynchronous operation was still pending.

Keith Barrow 30-Apr-13 15:07pm

The Dispose isn't the problem it works OK with a StreamWriter. Your code inside the using block is blocking the return operation (which was my first thought and asking about the using block). Something inside the using block is taking too much time. The best thing to do is to put a breakpoint on ss.Rate= 2; and step through each step to see what is taking the time. More than likely the using block this should be done on a separate thread/asynchonously anyway.

RobNO 30-Apr-13 15:11pm

I already debugged this method and it successfully runs through everything, without exceptions or prolonged blocks.

Why should the using block run on a separate thread?

Keith Barrow 30-Apr-13 15:24pm

From what I can determine from your code, you are writing a speech-synthesised voice to file. At the very least the file write is relatively long lived and will block the return until it has done its work. For a web API this isn't good as it blocks server resources.

RobNO 30-Apr-13 15:31pm

Yeah, and it is fine in my circumstance if it takes a second to write to a file and then give the response back.

However, Not to get carried away from the original question but I thought I read running new threads on a web server isn't good practice either because if there are many threads running then resources get tied up similarly to what I am currently doing.

Keith Barrow 30-Apr-13 16:00pm

Its all a question of balance I suppose. I was watching a web-api course last night (my sum experience with it), and he claimed blocking the thread like this was a bad plan. Not sure if the threading model is different, or I misunderstood :/

RobNO 30-Apr-13 16:09pm

Yea, a balance for sure. Thanks for all your help. I really appreciated it!

Keith Barrow 30-Apr-13 16:29pm

No Worries

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Keith Barrow · Answer 1 · 2013-04-30T09:56:00

C#

public string[] Get()
{
    string[] names = new string[3] { "Matt", "Joanne", "Robert" };
    using (SpeechSynthesizer ss = new SpeechSynthesizer())
    {
        //ss.Rate = -2;
        //var word = "Test This Two";

        //var filePath = HttpContext.Current.Request.MapPath("~/Content/sounds/" + word + ".wav");
    //    //ss.SetOutputToWaveFile(filePath);
        ss.Speak("Hello World");
    //    //ss.SetOutputToNull();
    //    //ss.Dispose();
    }
    return names;
}

Can't claim to know why but comment out the bold line and this works perfectly, uncomment it and you hear the text, but no response. Something in the synthesiser must be conflicting with the Web API Framework or taking too long to respond. Between this and the comments, I can't be much more help I'm afraid. Personally, I'd look at making the synth call asynchronous.