This is a simple demo app that shows how you can use the OpenTok Java SDK to archive (or record) Sessions, list archives that have been created, download the recordings, and delete the recordings.
First, download the dependencies using npm in this directory.
$ npm install
Next, 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.
$ export API_KEY=0000000
$ export API_SECRET=abcdef1234567890abcdef01234567890abcdef
Finally, start the app using node
$ node index.js
Visit http://localhost:3000 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 application (index.js).
Start by visiting the host page at http://localhost:3000/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.get('/host', function(req, res) {
var sessionId = app.get('sessionId'),
// generate a fresh token for this client
token = opentok.generateToken(sessionId, { role: 'moderator' });
res.render('host.ejs', {
apiKey: apiKey,
sessionId: sessionId,
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: 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:3000/start
URL. The route handler for this URL is shown below:
app.get('/start', function(req, res) {
opentok.startArchive(app.get('sessionId'), {
name: 'Node Archiving Sample App'
}, function(err, archive) {
if (err) return res.send(500,
'Could not start archive for session '+sessionId+'. error='+err.message
);
res.json(archive);
});
});In this handler, the startArchive() method of the opentok instance is called with the sessionId
for the session that needs to be archived. 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 optional second argument is for options like name, which is stored with
the archive and can be read later. The last argument is the callback for the result of this
asynchronous function. The callback signature follows the common node pattern of using the first
argument for an error if one occurred, otherwise the second parameter is an Archive object. As long
as there is no error, a response is sent back to the client's XHR request with the JSON
representation of the archive. 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:3000/stop/:archiveId URL where :archiveId represents the ID the client receives
in the 'archiveStarted' event. The route handler for this request is shown below:
app.get('/stop/:archiveId', function(req, res) {
var archiveId = req.param('archiveId');
opentok.stopArchive(archiveId, function(err, archive) {
if (err) return res.send(500, 'Could not stop archive '+archiveId+'. error='+err.message);
res.json(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 archiveId 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 req.param('archiveId') expression 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 public/js/host.js file. Read about the
OpenTok.js JavaScript library to learn more.
With the host view still open and publishing, open an additional window or tab and navigate to http://localhost:3000/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.get('/participant', function(req, res) {
var sessionId = app.get('sessionId'),
// generate a fresh token for this client
token = opentok.generateToken(sessionId, { role: 'moderator' });
res.render('participant.ejs', {
apiKey: apiKey,
sessionId: sessionId,
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 public/js/participant.js file.
Start by visiting the history page at http://localhost:3000/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.get('/history', function(req, res) {
var page = req.param('page') || 1,
offset = (page - 1) * 5;
opentok.listArchives({ offset: offset, count: 5 }, function(err, archives, count) {
if (err) return res.send(500, 'Could not list archives. error=' + err.message);
res.render('history.ejs', {
archives: archives,
showPrevious: page > 1 ? ('/history?page='+(page-1)) : null,
showNext: (count > offset + 5) ? ('/history?page='+(page+1)) : null
});
});
});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. 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 an
optional object to specify a count and offset. 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.ejs 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.get('/download/:archiveId', function(req, res) {
var archiveId = req.param('archiveId');
opentok.getArchive(archiveId, function(err, archive) {
if (err) return res.send(500, 'Could not get archive '+archiveId+'. error='+err.message);
res.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 getArchive() method of the opentok instance is used. The first
parameter is required and it is the archiveId. We use the same technique as above to read that
archiveId from the URL. The second parameter is a callback function, whose signature has arguments
for the error object and the resulting archive instance. Lastly, we send a redirect response back to
the browser with the archive's URL so the download begins.
The code for the delete route handler is shown below:
app.get('/delete/:archiveId', function(req, res) {
var archiveId = req.param('archiveId');
opentok.deleteArchive(archiveId, function(err) {
if (err) return res.send(500, 'Could not stop archive '+archiveId+'. error='+err.message);
res.redirect('/history');
});
});Once again the archiveId is retrieved from the URL of the request. This value is then passed to the
deleteArchive() method of the opentok instance. The callback only has an argument for an error
in case one occurred. 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.