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OpenTok Archiving Sample for .NET

This is a simple demo app that shows how you can use the OpenTok .NET SDK to archive (or record) Sessions, list archives that have been created, download the recordings, and delete the recordings.

Note: These instructions assume you will be using Visual Studio. Since the application runs as a self hosted OWIN-compatible console application, you should open Visual Studio using 'Run as administrator'. The sample projects are contained inside the OpenTok.sln solution at the top level.

Running the App

First, add your own API Key and API Secret to the Application Settings. For your convenience, the App.config file is set up for you to place your values into it.

    <add key="API_KEY" value="000000" />
    <add key="API_SECRET" value="abcdef1234567890abcdef" />

Next, make sure the Archiving project is set as the Solution's Startup project. This can be done by opening the Properties of the solution, and selecting it under Common Properties > Startup Project.

Lastly, the dependencies of the application are referenced using NuGet. Package Restore is a feature of NuGET 2.7+ and as long as your installation of Visual Studio has the NuGet extension installed with a later version, the package should be installed automatically on launch. Otherwise, use the NuGET Packge Restore guide.

Choose Start (Ctrl+F5) to run the application.

Visit http://localhost:8080 in your browser. You can now create new archives (either as a host or as a participant) and also play archives that have already been created.


This demo application uses the same frameworks and libraries as the HelloWorld sample. If you have not already gotten familiar with the code in that project, consider doing so before continuing.

The explanations below are separated by page. Each section will focus on a route handler within the main module (MainModule.cs).

Creating Archives – Host View

Start by visiting the host page at http://localhost:8080/host and using the application to record an archive. Your browser will first ask you to approve permission to use the camera and microphone. Once you've accepted, your image will appear inside the section titled 'Host'. To start recording the video stream, press the 'Start Archiving' button. Once archiving has begun the button will turn green and change to 'Stop Archiving'. You should also see a red blinking indicator that you are being recorded. Wave and say hello! Stop archiving when you are done.

Next we will see how the host view is implemented on the server. The route handler for this page is shown below:

    Get["/host"] = _ =>
        dynamic locals = new ExpandoObject();

        locals.ApiKey = opentokService.OpenTok.ApiKey.ToString();
        locals.SessionId = opentokService.Session.Id;
        locals.Token = opentokService.Session.GenerateToken();

        return View["host", locals];

If you've completed the HelloWorld walkthrough, this should look familiar. This handler simply generates the three strings that the client (JavaScript) needs to connect to the session: ApiKey, SessionId and Token. After the user has connected to the session, they press the 'Start Archiving' button, which sends an XHR (or Ajax) request to the http://localhost:8080/start URL. The route handler for this URL is shown below:

Post["/start"] = _ =>
Archive archive = opentokService.OpenTok.StartArchive(
    name: ".NET Archiving Sample App",
    hasAudio: (Boolean)(this.Request.Form.hasAudio),
    hasVideo: (Boolean)(this.Request.Form.hasVideo),
    outputMode: (this.Request.Form.outputMode == "composed" ? OutputMode.COMPOSED : OutputMode.INDIVIDUAL)
return archive;

In this handler, the StartArchive() method of the OpenTok instance is called with the Id for the session that needs to be archived. The remaining arguments are a set of optional properties for the Archive. The Name is stored with the archive and can be read later. The hasAudio, hasVideo, and outputMode values are read from the request body. In this case, as in the HelloWorld sample app, there is only one session created, which is stored in the OpenTokService, and it is used here and for the participant view. This will trigger the recording to begin. The response sent back to the client's XHR request will be the JSON representation of the archive, which Nancy knows how to serialize from the object. The client is also listening for the archiveStarted event, and uses that event to change the 'Start Archiving' button to show 'Stop Archiving' instead. When the user presses the button this time, another XHR request is sent to the http://localhost:8080/stop/:archiveId URL where :archiveId represents the ID the client receives in the 'archiveStarted' event. The route handler for this request is shown below:

    Get["/stop/{id}"] = parameters =>
        Archive archive = opentokService.OpenTok.StopArchive(;
        return archive;

This handler is very similar to the previous one. Instead of calling the StartArchive() method, the StopArchive() method is called. This method takes an archive ID as its parameter, which is different for each time a session starts recording. But the client has sent this to the server as part of the URL, so the expression is used to retrieve it from the route matched segment.

Now you have understood the three main routes that are used to create the Host experience of creating an archive. Much of the functionality is done in the client with JavaScript. That code can be found in the Content/js/host.js file. Read about the OpenTok.js JavaScript library to learn more.

Creating Archives - Participant View

With the host view still open and publishing, open an additional window or tab and navigate to http://localhost:8080/participant and allow the browser to use your camera and microphone. Once again, start archiving in the host view. Back in the participant view, notice that the red blinking indicator has been shown so that the participant knows his video is being recorded. Now stop the archiving in the host view. Notice that the indicator has gone away in the participant view too.

Creating this view on the server is as simple as the HelloWorld sample application. See the code for the route handler below:

    Get["/participant"] = _ =>
        dynamic locals = new ExpandoObject();

        locals.ApiKey = opentokService.OpenTok.ApiKey.ToString();
        locals.SessionId = opentokService.Session.Id;
        locals.Token = opentokService.Session.GenerateToken();

        return View["participant", locals];

Since this view has no further interactivity with buttons, this is all that is needed for a client that is participating in an archived session. Once again, much of the functionality is implemented in the client, in code that can be found in the Content/js/participant.js file.

Past Archives

Start by visiting the history page at http://localhost:8080/history. You will see a table that displays all the archives created with your API Key. If there are more than five, the older ones can be seen by clicking the "Older →" link. If you click on the name of an archive, your browser will start downloading the archive file. If you click the "Delete" link in the end of the row for any archive, that archive will be deleted and no longer available. Some basic information like when the archive was created, how long it is, and its status is also shown. You should see the archives you created in the previous sections here.

We begin to see how this page is created by looking at the route handler for this URL:

    Get["/history"] = _ =>
        var page = ? (int) : 1;
        var offset = (page - 1) * 5;
        ArchiveList archives = opentokService.OpenTok.ListArchives(offset, 5);

        string showPrevious = page > 1 ? "/history?page=" + (page - 1).ToString() : null;
        string showNext = archives.TotalCount > (offset + 5) ? "/history?page=" + (page + 1).ToString() : null;

        dynamic locals = new ExpandoObject();
        locals.Archives = archives;
        locals.ShowPrevious = showPrevious;
        locals.ShowNext = showNext;

        return View["history", locals];

This view is paginated so that we don't potentially show hundreds of rows on the table, which would be difficult for the user to navigate. So this code starts by figuring out which page needs to be shown, where each page is a set of 5 archives. The page number is read from the request's query string parameters as a string and then cast to an int. The offset, which represents how many archives are being skipped is always calculated as five times as many pages that are less than the current page, which is (page - 1) * 5. Now there is enough information to ask for a list of archives from OpenTok, which we do by calling the ListArchives() method of the OpenTok instance. The first parameter is the offset, and the second is the count (which is always 5 in this view). If we are not at the first page, we can pass the view a string that contains the relative URL for the previous page. Similarly, we can also include one for the next page. Now the application renders the view using that information and the partial list of archives.

At this point the template file views/History.cshtml handles looping over the array of archives and outputting the proper information for each column in the table. It also places a link to the download and delete routes around the archive's name and its delete button, respectively.

The code for the download route handler is shown below:

    Get["/download/{id}"] = parameters =>
        Archive archive = opentokService.OpenTok.GetArchive(;
        return Response.AsRedirect(archive.Url);

The download URL for an archive is available as a property of an Archive instance. In order to get an instance to this archive, the GetArchive() method of the OpenTok instance is used. The only parameter it needs is the archive ID. We use the same technique as above to read that archive ID from the URL. Lastly, we send a redirect response back to the browser so the download begins.

The code for the delete route handler is shown below:

    Get["/delete/{id}"] = parameters =>
        return Response.AsRedirect("/history");

Once again the archive ID is retrieved from the URL of the request. This value is then passed to the DeleteArchive() method of the OpenTok instance. Now that the archive has been deleted, a redirect response back to the first page of the history is sent back to the browser.

That completes the walkthrough for this Archiving sample application. Feel free to continue to use this application to browse the archives created for your API Key.

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