Codebrocken: Mojo

Mittwoch, 1. Februar 2012

webOS: Detecting Enyo on phones

With the trojan horse maps update for all webOS devices, every device has the option of running Enyo applications. Which is great, but how can you determine whether the user has updated his phone or not?

Arthur Thornton posted a very nice solution in the webOS developer forums.

In the likely situation that no update to older devices is pushed out including enyo, here is a solution...it isn't pretty, but it will get the job done.

The very first thing you need to do is mention in your app description that your app requires "updated system software" included in the Maps app. This way, the users should know to expect this as a requirement, and even though many users don't read the description (grr...) you're still covered by mentioning this.

Then use the following code in your app:

index.html

Code:
<!doctype html>
<html>
  <head>
    <title></title>
    <meta name="viewport" content="height=device-height" />
    <script src="C:\Program Files (x86)\HP webOS\SDK\share\framework\enyo\1.0\framework\enyo.js" type="text/javascript"></script>
  </head>
  <body>
    <script type="text/javascript">
      if (typeof enyo == "undefined")
        window.location = "./requiresEnyo.html";
      else
        new MyApp().renderInto(document.body);
    </script>
  </body>
</html>

requiresEnyo.html

Code:
<!doctype html>
<html>
  <head>
    <title>Install Maps and Enyo</title>
    <meta name="viewport" content="height=device-height" />
    <script src="/usr/palm/frameworks/mojo/mojo.js" type="text/javascript" x-mojo-version="1" />
  </head>
  <body>
    <div style="padding: 5px">
      Attention: This application requires an updated version of the system software which is not available on your phone. To install this updated software, you must install the updated Maps app by tapping the below button (will open the App Catalog):
    </div>
    <div class="palm-button" onclick="installEnyo()">Install</div>
    <script>
      window.onload = function() {
        PalmSystem.stageReady(); // required for page to load
      };
      function installEnyo() {
        window.location = "http://developer.palm.com/appredirect/?packageid=com.palm.app.maps";
      }
    </script>
  </body>
</html>

Note that this loads Mojo (which will obviously be on the device) in a separate HTML file *if* enyo isn't already on the device (i.e. a Pre2). This was tested to work on my Pre2.

Also note that to put enyo in your app, your users must be using webOS 1.4.5 or newer because the maps app has a minimum webOS version of 1.4.5 (and thus, users prior to 1.4.5 won't see it in the Catalog and won't be able to update) due to (I'm assuming) using the version 2.0 packaging format.

If you have your app currently deployed to users running webOS versions prior to 1.4.5, you will have to retain a Mojo version in it (because the app can still be updated even if you change minimum OS version to 1.4.5 unless changes have recently gone into effect to fix that; this doesn't cause issues for the Maps app because technically, that app is not update-capable on devices prior to the Pre3 without the workaround they came up with).

Arthur Thornton
webOS Application Engineer
Appstuh

Samstag, 21. Januar 2012

webOS: Open a socket

If you use Enyo or Mojo for your webOS application development, you cannot connect to a server that runs anything else than a http protocol. This limitation comes from webOS programs effectively running inside a web browser. Therefore they can make only http requests using XmlHttpRequest calls.

But webOS Version 2.X introduced support for node.js. Programs can use this library to open a socket to any server using any protocol. The downside is, that you have to do a little bit of work to get this thing moving: you have to write your own javascript service.

This code opens a connection to port 28820 on host 172.20.1.65 and sends the string "HELLO" with a line break. When it receives an response, it is written to the console.

// import node.js net library
var net = IMPORTS.require('net');

// constructor for service assistant
var socketAssistant = function() {
};

// function is called by framework to execute the service
socketAssistant.prototype.run = function(future) {
    // future contains the result of the function call
    // use it to transfer information to your program
    future.result = {
        reply : "Hello " + this.controller.args.name + "!"
    };

    // check if the node.js net library has been loaded
    if (!net) {
        console.error("net == NULL");
    }

    // create a new client connection
    var client = net.createConnection(28820, '172.20.1.65');

    // event handler when data arrives from the server
    client.on("data", function(data) {
        console.error("Received data: " + data.toString());
    });

    // event handler called after a connection has been established
    client.on("connect", function() {
        console.error("Connection established !");
        client.write("HELLO\n"));
    });

    // event handler called in case of an error
    client.on('end', function() {
        console.error("Connection killed.");
    }); 
};

The code is pretty simple but does not contain the framework needed to integrate it into a service. That is fodder for another post soon. Meanwhile take a look at the SDK documentation for writing javascript services.

Older versions of webOS only support node.js 0.2.3. Version 3.0.4 of webOS made an update to node.js 0.4.12 (see release notes). Be aware of that fact when using the node.js functions.

See the node.js (version 0.2.3) documentation for what you can do with the connection.