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README.md
archiving.py
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README.md

OpenTok Archiving Sample for Python

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

Running the App

First, we highly recommend setting up a virtualenv.

$ virtualenv venv
$ source venv/bin/activate

Next, download the dependencies using Pip, from the current directory:

(venv)$ pip install -r requirements.txt

Then add your own API Key and API Secret to the environment variables. There are a few ways to do this but the simplest would be to do it right in your shell.

(venv)$ export API_KEY=0000000
(venv)$ export API_SECRET=abcdef1234567890abcdef01234567890abcdef

Finally, start the server.

(venv)$ python archiving.py

Visit http://localhost:5000/ 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.

Walkthrough

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 application (archiving.py).

Creating Archives – Host View

Start by visiting the host page at http://localhost:5000/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:

@app.route("/host")
def host():
    key = api_key
    session_id = session.session_id
    token = opentok.generate_token(session_id)
    return render_template('host.html', api_key=key, session_id=session_id, token=token)

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: api_key, session_id 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:5000/start URL. The route handler for this URL is shown below:

@app.route("/start", methods=['POST'])
def start():
    has_audio = 'hasAudio' in request.form.keys()
    has_video = 'hasVideo' in request.form.keys()
    output_mode = OutputModes[request.form.get('outputMode')]
    archive = opentok.start_archive(session.session_id, name="Python Archiving Sample App",
                                    has_audio=has_audio, has_video=has_video, output_mode=output_mode)
    return archive.json()

In this handler, the start_archive() method of the opentok instance is called with the session_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 has_audio, has_video, and output_mode values are read from the request body; these define whether the archive will record audio and video, and whether it will record streams individually or to a single file composed of all streams. In this case, as in the HelloWorld sample app, there is only one session created 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 is returned from the json() method. 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:5000/stop/<archive_id>> URL where <archive_id> represents the ID the client receives in the 'archiveStarted' event. The route handler for this request is shown below:

@app.route("/stop/<archive_id>")
def stop(archive_id):
    archive = opentok.stop_archive(archive_id)
    return archive.json()

This handler is very similar to the previous one. Instead of calling the start_archive() method, the stop_archive() 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 archive_id argument from the route matcher is used to retrieve it.

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 static/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:5000/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:

@app.route("/participant")
def participant():
    key = api_key
    session_id = session.session_id
    token = opentok.generate_token(session_id)
    return render_template('participant.html', api_key=key, session_id=session_id, token=token)

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 static/js/participant.js file.

Past Archives

Start by visiting the history page at http://localhost:5000/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:

@app.route("/history")
def history():
    page = int(request.args.get('page', '1'))
    offset = (page - 1) * 5
    archives = opentok.get_archives(offset=offset, count=5)

    show_previous = '/history?page=' + str(page-1) if page > 1 else None
    show_next = '/history?page=' + str(page+1) if archives.count > (offset + 5) else None

    return render_template('history.html', archives=archives, show_previous=show_previous,
                            show_next=show_next)

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 (defaulting to 1 if its not present) and then casted into 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 get_archives() method of the opentok instance. This method optionally takes the offset and count that was just calculated. 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 templates/history.html 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:

@app.route("/download/<archive_id>")
def download(archive_id):
    archive = opentok.get_archive(archive_id)
    return redirect(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 get_archive() 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:

@app.route("/delete/<archive_id>")
def delete(archive_id):
    opentok.delete_archive(archive_id)
    return redirect(url_for('history'))

Once again the archive_id is retrieved from the URL of the request. This value is then passed to the delete_archive() 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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