Server-side

An example Java integration

On the server side we have a servlet running as if it were part of a company portal. It retrieves the username of the currently signed in user, and then uses the Jabber Guest REST API to create a call link for that user to call whatever number was passed in.

The reason we don't do this directly from the client is that the Jabber Guest REST APIs require admin credentials to use, which of course we would not want to embed in the Java Script of a web application.

Link attributes

Our example servlet is creating a link for the signed in user for a specific destination (extension), and what we do is generate a random request path to make a unique call url, and set an expiration on the link so that it can only be used for one call:

    // Destination is set by "destination" parameter
    String destination = request.getParameter("destination");

    // Set displayName to the user's name
    String displayName = request.getUserPrincipal().getName();
    String requestPath = UUID.randomUUID().toString();

    // Set link to be valid for 10 minutes
    Date validBefore = new Date((new Date()).getTime() + (10 * 60 * 1000));
    Date validAfter = null; // Valid now

Presumably the call is going to be made right away, so we provide a 10 minute window for the link to be active.

The link should also be deleted so we don't clutter up the system with expired links, but the expiration gives us a safeguard there just in case (and so we can show how to use expiration in our example.)

Calling the REST API

The next thing the servlet does is call the REST API on Jabber Guest to create the link we defined above. To do this we can use BASIC authentication and some admin credentials (the servlet reads those in from web.xml -- definitely not recommended for production!)

Step 1 - Create a JSON link object

The link API is very REST-ful, so we need to POST a JSON object to the links url to create a new link. JSON is fairly simple and you can easily build up a string of JSON by hand, but for this demo we're using a lightweight JSON library to keep things simple (https://github.com/ralfstx/minimal-json):

JsonObject linkObject = new JsonObject()
    .add( "isEnabled", true )
    .add( "destination", destination )
    .add( "displayName", displayName )
    .add( "callerName", callerName )
    .add( "requestPath", requestPath );
if (validAfter != null)
    linkObject.add( "validAfter", dateToJSON(validAfter));
if (validBefore != null)
    linkObject.add( "validBefore", dateToJSON(validBefore));

The only real trick there is that we need to get the dates in a nice format - this particular JSON library doesn't do that automatically. So in case you run into this too, here's a snippet for doing that converstion:

private static String dateToJSON(Date d) {
    SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'");
    df.setTimeZone(TimeZone.getTimeZone("UTC"));
    return(df.format(d));
}

Anway, we now have an object that we can get as a JSON string by simple calling toString().

Step 2 - POST JSON to server

The next step is to POST our JSON to the server. Again to keep things simple we're using a library to help us out here, which helps to illustrate the ideas without having to write a bunch of boilerplate helper code. This time we went with the excelent http-request library that can be found here: https://github.com/kevinsawicki/http-request

Before showing the code snippet to create a link, here are a few things to keep in mind:

1. Set the Content-Type header to "application/json" so the server knows we are sending it JSON
2. Success is determined by a 201 code (HTTP code for CREATED)
3. The URL of the created link is returned in the Location header
4. Java doesn't like self-signed certificates by default, which is what Jabber Guest servers come with

That might sound like a lot, but fortunately in code it's really fairly straight forward:

HttpRequest r = HttpRequest
        .post(this.linksUrl)
        .contentType("application/json")
        .accept("application/json")
        .basic(this.accountName,this.accountPassword)
        .trustAllCerts()    // For self signed certs
        .send(linkObject.toString());

// Look for HTTP code 201 ("CREATED")
if (r.code() == 201)
    // Link created, get link URL from Location header
    return r.header("Location");

Note that for production you probably do not want to use "trustAllCerts()" because that will create a "man in the middle" attack vulnerability.

Also note that HTTP code 200 OK does not mean that the link was created, so be careful about that in your own application.