AT&T Best Practices Guide for App Development

When considering the various best practices surrounding the design of Mobile Web Experiences and Architectures, such works as the W3C’s Mobile Web Application Best Practices guide, or the excellent Mobile Web Best Practices site, and of course, the seminal text, Mobile First, are likely to come to mind. The concepts and strategies presented in these works are a staple in the design of many modern Mobile Web Experiences and are without question an invaluable resource. In addition to these and other similarly related works, another new and valuable resource has been made available from a very important player in the Mobile Space indeed – an actual Wireless Carrier, AT&T.

Recently, I was contacted by a representative of the AT&T Developer Program informing me of the research conducted by the AT&T Research Labs and, the subsequent resources made available by AT&T as a result of their findings. Since I was unaware of this work, I was very interesting in learning more and, after reading the introductory statements, I was quite eager to apply AT&T’s recommendations as well; to quote specifically:

We quickly saw that a few, simple design approaches could significantly improve application responsiveness.

Having read through the material in it’s entirety (provided below) I must say I am rather impressed. The information provided has very real and practical implications on the design of Mobile Web Applications. Specifically, I found the clear and concise explanation of the underlying implementation of the Radio Resource Control (RRC) protocol to be particularly relevant and useful. RRC is by far one of the most important design factors to consider in terms of battery life and Application responsiveness and, as the research suggests, this may not have been common knowledge.

By far, the most interesting and notable aspect of the AT&T Research Lab’s work in this area is the fact that all of the information provided is applicable in the context of all Wireless Carriers, not just AT&T. That is, the recommendations given, such as those regarding the RRC State Machine, for example, are all based on carrier-independent standards and protocols implemented by all Wireless Carriers. As such, understanding the implementation specifics and recommendations provided is certain to prove valuable for all users of your Application, regardless of their Carrier.

If you haven’t all ready, I highly recommend reading and applying the principles provided by AT&T’s research to your current and future Mobile Web Application Designs.

AT&T Research Labs: Mobile Application Resources

Build Efficient Apps
Profiling Resource Usage for Mobile Applications: A Cross-layer Approach

January 15, 2012 Browsers / Design Patterns / HTML5 / JavaScript / Software Engineering / UX Design
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Configuring iOS HTTP Monitoring

When developing Web Applications for the Mobile Web Experience it is often useful to have a clear view into all HTTP requests and responses sent between the client and server. This is quite simple to accomplish when developing Web Applications for the Desktop as, the browser is running locally so any standard HTTP Monitor will suffice. And, while it is a normal part of a typical development workflow to run an application locally the majority of the time, testing on each target device is obviously an essential part of the process as well.

Luckily, with Charles, on iOS this is quite simple to accomplish.

Configuration

To configure Charles to proxy all requests from an iOS device, simply follow these basic steps:

  1. From your iOS Device, open Settings.
  2. Go to Wi-Fi, select your Network and select the Blue “arrow” icon.
  3. Scroll to HTTP Proxy and select the Manual Button.
  4. In the Server field, enter the IP address of your development machine.
  5. In the port field, enter port 8888 (the default port to which Charles binds).
  6. Leave Authentication set to Off.

And that’s all there is to it. Now, open Mobile Safari and go to your Web Application’s URL (or any page on the web for that matter). On your development machine, in Charles you will receive a prompt with the IP Address of your Mobile Device, click “Allow” and you are all set. When you are done working, make sure to turn off HTTP Proxy on your device.

Additional Note

While this article may be focused on Mobile Web Applications, these same configurations apply to all HTTP traffic from any application on your device that requires resources over the web.

December 16, 2011 Browsers
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External Templates in jQote2

The jQote2 API Reference provides plenty of useful examples which are sure to help users get up and running quickly. I found it a bit unclear, though, as to how templates could be loaded externally as, in the reference examples, templates are defined within the containing page. For the sake of simplicity this approach certainly makes sense in the context of examples. However, in practice, templates would ideally be loaded externally.

While jQote2 provides a perfect API for templating, it does not provide a method specifically for loading external templates; this is likely due to the fact that loading external templates could easily be accomplished natively in jQuery. However, since this is a rather common development use case, having such a facility available would be quite useful.

After reviewing the comments I came across a nice example from aefxx (the author of jQote2) which demonstrated a typical approach to loading external templates which was simular to what I had been implementing myself.

And so, I wrote a simple jQuery Plug-in which provides a tested, reusable solution for loading external templates. After having leveraged the Plugin on quite a few different projects, I decided to open source it as others may find it useful as well.

Using the Plugin

Using the jQote2 Template Loader plugin is rather straight forward. Simply include jQuery, jQote2 and the jquery.jqote2.loader-min.js script on your page.

As a basic example, assume a file named example.tpl exists, which contains the following template definition:

We can load the example.tpl template file described above via $.jqoteload as follows:

After example.tpl has been loaded, from another context we can access the compiled templates via their template element id. In this example "articles_tpl".

You can grab the source and view the example over on the jQote2 Template Loader Github page.

December 12, 2011 APIs / Design Patterns / HTML5 / JavaScript
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DHTMLX Touch 1.0 Released

Last week, shortly after I blogged about the release of jQuery Mobile 1.0, I received an email informing me of the release of another Mobile Web Framework: DHTMLX Touch 1.0.

Being that I was unfamiliar with DHTMLX Touch (as I have been using jQuery Mobile almost exclusively), I was quite interested to learn more; and, having tried the Examples and reviewed the Documentation, I was rather impressed by DHTMLX Touch.

And so, if you haven’t already, check it out.

November 23, 2011 HTML5 / JavaScript
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Function Overwriting in JavaScript

Whether intentional, or simply a by-product of it’s design, Javascript, being a dynamic language, allows for a level of expressiveness which most any seasoned programmer would come to appreciate. Javascript naturally provides the ability to implement some rather intriguing and quite unique patterns; one of which is the ability to overwrite a function at runtime.

Function Overwriting

Function Overwriting (also known as “Self-Defining Functions” or “Lazy Defining Functions”) provides a pattern which, as stated above, allows for overwriting a function’s definition at runtime. This can be accomplished from outside of the function, but also from within the function’s implementation itself.

For example, on occasion a function may need to perform some initial piece of work, after which, all subsequent invocations would result in unnecessarily re-executing the initialization code. Typically, this issue is addressed by storing initialization flags or refactoring the initialization code to another function. While such a design solves this problem, it does result in unnecessary code which will need to be maintained. In JavaScript, perhaps a different approach is in order: we can simply redefine the function after the initialization work has been completed.

A possible candidate use-case for Function Overwriting is Feature Detection as, detecting for specific feature support in the Browser typically only needs to be tested once, at which point subsequent tests are unnecessary.

Below is a basic example of implementing Function Overwritting in the context of an abstraction of the HTML5 Geolocation API.

Considerations

Since functions are objects in Javascript, it is important to keep in mind that if you add a property or method to a function (either statically or via the function’s prototype), and then overwrite the function, you will have effectively removed those properties or methods as well. Also, if the function is referenced by another variable, or by a method of another object, the initially defined implementation will be preserved and the overwriting process will not occur. As such, be mindful when implementing this pattern. As a general rule of thumb, I typically only implement Function Overwriting when the function being redefined is in a private scope.

Concluding Thoughts

As you can see, Function Overwriting provides a convenient facility for optimizing code execution at runtime. There are many use-cases for dynamically overwriting functions and, where appropriate, they can certainly provide value in terms of performance and code maintainability.

Below you can find an example which demonstrates two basic Function Overwriting implementations. Simply load the page and add some breakpoints in Firebug to test the execution paths; both before and after overwriting each function occurs, or you can simply view the source.
Example

November 19, 2011 Browsers / Design Patterns / HTML5 / JavaScript / Object Oriented Design / Refactoring
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Refreshing listviews in jQuery Mobile

When dynamically creating or updating a list in jQuery Mobile; either via AJAX or by other means, one must take care to explicitly invoke the target listview widget to “refresh” in order to instruct the framework to apply the augmented markup and styles to the corresponding elements of the underlying list.

For example, consider the following simplified example which creates an li element for each item in an Array:

While this will create the list items and add them to the target listview ul element, JQM will not auto enhance the newly added items unless instructed to do so. I imagine this is due to a necessary design decision as, constantly monitoring the DOM for changes would certainly incur a performance hit.

In order to correct this, we just need to invoke .listview("refresh"); after appending the new elements to the list. This will notify JQM to apply the expected enhancements. And so, the following example will result in the expected list enhancements being applied:

You can try an example which demonstrates both of the above implementations here.

November 18, 2011 APIs / HTML5 / JavaScript
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