Dojo’s improved RPC and new REST services can be used with a wide array of web services. One particular use is Amazon’s Simple Storage Service (S3). Dojo can connect to Amazon S3’s with a trivial proxy and be used as a normal RPC service. Not only that, Amazon S3 is a REST service and therefore it can be used as a data store with Dojo’s new REST implementation of dojo.data, JsonRestStore. You can read and write to your S3 database using the convenient Dojo Data API, and use the data store in Dojo widgets.

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Some sites can defer most, if not all, of their JavaScript-driven progressive enhancements until well after the page has loaded. Even so-called “lightweight” libraries like JQuery are far too heavy for some environments…not because they (like Dojo) pull in all the code needed to use them, but because they do it all up-front. Often the best time to pay the expense of loading, parsing, and executing JavaScript code is when the user takes an action that needs the enhancement to run. Dojo already gives you the best tools available anywhere to defer loading modules until you actually use them; other than those provided by dojo.js itself…but what about dojo.js? What if even the small size of Dojo is too big for your page? This need to load as fast as possible and defer work is never greater than in mobile applications. The best-performing thing to do is always to hand-write all the code you’ll need and never use more script than that…but there are complications. Not being able to share your code between developers (let alone between pages) can be a huge disadvantage. The code is also likely to be slow, buggy, and unmaintainable. There’s a real reason why toolkits like Dojo are so incredibly popular: they make much of this pain go away at the cost of initial download size. Why would anyone want to invite the pain back?

So we need some middle ground: a common, expected API surface area combined with a trivial initial footprint to ensure that pages load as fast as possible. How small could we make such a thing? Turns out, 6K.

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I was doing some research on script loading speed tests. Each script load required the page to be refreshed, making it difficult to log the time to Firebug and get an average. It was certainly too much trouble to write some PHP scripts and connect to a database; and possibly even worse would be having to pull out a pencil and paper and write the times down. I’m not even sure I have a pencil.

The obvious solution was to write the data to a cookie. I also thought the solution was universal enough to blog about so others could use it too.

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SMS is a great way to push small amounts of text to mobile users. But what happens when your application needs to send more than 140 characters of information? Most modern phones, including Apple’s iPhone, support the ability to launch the mobile web browser using the URL embedded in the SMS message. Your application can create a short URL that points to the content you need to send and send the URL in the body of the SMS instead of the content itself. The user experience varies from phone to phone. On the iPhone, the user simply touches the link; on other phones, there is usually a menu option that will activate the url.

The URL is subject to the same size limits as any other SMS message. Keeping the URL as short as possible is key, allowing you to send descriptive text along with the message to give the user an idea as to what they will be viewing when they click the link. URL shortening services like tinyurl will keep your URL to around 25 characters. Twitter users are no doubt familiar with this idea, whether they send Tweets from their phone or not.

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A very useful feature of Dojo is the dojox.data.ServiceStore data store. It allows you to layer a dojo.data API on top of any web service, opening up a world of uses from your own client-side components. Kris Zyp briefly mentioned the topic in his recent article on JsonRestStore, and the past couple of weeks have seen a bunch of refinements to the component to get it ready for next month’s Dojo 1.2 release. Let’s take a quick look at how to make it work with the web service of your choice.

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I recently came across a situation where I needed to manage a set of nodes and widgets to perform a number of visual operations as well as manage some data between the client and a server back end. While this was a custom operation, it was common to a number of different places within the app. Initially, things were quite simple and I managed with a few functions and connections primarily using dojo.query(). In the end, I ended up with a simple way to make a dijit._Templated widget that uses its source node as a template instead.

Widgets can easily take advantage of existing source nodes to define how they might end up rendering. They might use the source nodes to define a data set. They could be widgets that manage a number of child widgets as is done with the various Dijit Layout widgets. However, under normal circumstances, a widget’s source node is replaced by the nodes generated from its template or the original source nodes are moved to a container node within your template. What we are looking for is a way to define a flyweight widget that can encapsulate behaviors and data, provides for dynamic template generation, and retains the utility of dojoAttachPoints and dojoAttachEvents from the templating system.

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A few weeks ago, some of the guys at SitePen were commenting that I was using Flash on my personal web site for a Flickr Badge. I responded that if Dojo had similar functionality, I would easily replace the badge. A couple of weeks later, Peter Higgins and Bryan Forbes of SitePen rose to the task and created dojox.image.FlickrBadge.

This weekend I had a chance to put their work to the test, and I’m impressed. Using the new Flickr badge is quite easy:

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jabsorb is lightweight Ajax framework that uses JSON-RPC to communicate method calls from JavaScript to the Java server. Because of Dojo’s pluggable RPC and SMD capabilities, Dojo can easily be used to communicate method calls to the jabsorb server framework. Together, Dojo and jabsorb provide a very simple solution for integrating a UI with a Java back-end. Here we will see a quick demonstration of making a Java object available for remote calls from Dojo.

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Non-trivial data often has structures that cannot be well-defined with normal linear, acyclic data descriptions. Data that consists of cycles, many-to-one relationships, and non-local references often requires custom strategies for serialization and transfer of the data over JSON. Dojo 1.2 has added support for JSON referencing with the dojox.json.ref module. This module provides support for several forms of referencing including circular, multiple, inter-message, and lazy referencing using id, path, and combined referencing forms.

These references can be automatically generated on serialization and resolved on deserialization. JSON referencing is designed to decouple the topology of data structures from the meaning of the data structures in a way that is consistent with runtime object models of modern OO languages (foremost JavaScript). Separating graph connectedness concerns allows referencing and dereferencing to be handled by dojox.json.ref with minimal or no knowledge of and integration with higher level JSON consumers and producers, and permits more extensive JavaScript serialization capabilities.

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Part 1 of this guide on Dojo charting covered a basic charting example and the options available in defining our chart type. Today we will examine the options for defining our axes and data sets.

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