web sockets - Eric Feminella

The HTML5 Family

“If everyone is moving forward together, then success takes care of itself.” – Henry Ford

The HTML5 Family of Technologies has been receiving considerable coverage lately; and, rightfully so, as, many next generation browsers – specifically those in the Mobile space based on WebKit: Android, iPhone, iPad, Blackberry etc. are now beginning to implement it’s specification, or parts thereof. On the Desktop more HTML5 support is also being seen in the latest versions of Chrome, Firefox, Safari, IE9 and Opera.

The HTML5 Family of technologies will without question play a vital role in the future of the web; and currently, in the mobile Web space, that future is now.

A Brief Overview of the HTML5 Family

For anyone who is unfamiliar with what has been termed “The HTML5 Family“, allow me to provide succinct overview of the technologies which I feel encompass what has already become a rather overloaded term. In general, on a very high level, I would summarize the HTML5 Family simply as follows:

HTML5
CSS3
JavaScript

While the above could be considered the umbrella Technologies upon which The HTML5 Family is based, there are certainly more associated technologies which themselves further augment what could be considered the HTML5 Family, some of which are (based on current specification status at the time of this writing June 22^nd, 2010):

Microdata
Geolocation API
Device APIs
Web Storage (localStorage, sessionStorage) APIs
Web SQL Database API
Web Workers API
Web Sockets API

HTML5

First, HTML5. HTML5 is the next major revision of HTML which aims to advance the open Web through web standards and semantically rich content. HTML5 defines an emphasis on semantic structure and meaning.

In general, HTML5 provides a content model which can be broadly defined into the following categories: Metadata content, Flow content, Sectioning content, Heading content, Phrasing content, Embedded content and Interactive content as well as form-associated elements etc.. HTML5 defines new tags such as canvas,
audio, video, keygen, header, footer, nav, article, aside, datalist and more.

CSS3

CSS3 has been broken out into a collection of modules, each of which have their own specifications and are currently in various states of completion. These modules include such examples as Selectors, Transitions, Animations, Namespaces, Color, Fonts, Advanced Layout, Background and more. Some rather amazing designs can now be created purely in CSS3.

JavaScript

Explaining what JavaScript is may seem like a moot point as it is the language of the browser and therefore, the language of the web. However, it is important to outline some key underlying specifics of the language. In particular, JavaScript is a dynamic, prototypal, object-oriented scripting language. Its prototypal nature is quite different from the classical concepts of traditional object oriented languages. In order to get the most out of the language one needs to understand and embrace prototypalism and dynamism. Many of JavaScript’s true potential can be mistakenly overshadowed by it’s assumed design flaws; however, this needn’t be the case. As long as one understands the fundamental concepts of the language, it’s true potential can be realized to enrich development and allow for a level of expressiveness unmatched in type-safe languages.

Microdata

HTML5 Microdata provides a mechanism which allows machine-readable data to be embedded in HTML documents in the form of annotations, with an unambiguous parsing model. Microdata is compatible with numerous data formats such as JSON. Micro-data is intended to provide a standard to replace other similar concepts such as RDFa, from which browsers and other applications can discover relevant content based on the context of an applications markup. Such examples include markup for contact information, calendar events and more. This markup is understood by HTML5 compatible browsers which can then automatically offer to add the relevant content to the appropriate application. At an implementation level, microdata simply consists of a group of name-value pairs; with the groups being called items, and each name-value pair is a property.

Geolocation API

The HTML5 Geolocation API is rather straightforward; it simply provides a means by which the location of a device can be determined via a native API (as opposed to say, determining the clients IP address). The Geolocation spec is currently in last call status in the W3C.

Device APIs

Device APIs are client-side APIs which allow for direct interaction with native device services such as a device Camera, Calendar, Contacts etc.

Web Storage API

The Web Storage API allows for the persistence of local (permanent) and session based (browser session) data on the client. The API for Web Storage is extremely simple as it is based upon simple Key / Value pairs; with which Keys are simply Strings. Each site contains its own separate storage area.

Web SQL Database

While not a part of the actual HTML5 specification, the Web SQL Database presents some extremely interesting possibilities within Web Applications. The Web SQL Database provides a set of APIs which allow for the manipulation of client-side databases using SQL. The Web SQL Database is based upon SQLite (3.1.19) thus supporting the features as specified therein.

Web Workers API

Web Workers provide a mechanism by which web content can execute scripts in background threads. Web Workers allow for a much needed multi-threaded implementation for web based applications executing in a browser. While somewhat similar, Web Workers are different from threads in that they are primarily intended for executing long running, expensive computations and algorithms so as to facilitate non-blocking UI background processes. One specific aspect of Web Workers which has considerable positive implications for the web moving forward is that they run in native threads as opposed to Green Threads; as is the case in VM architectures. This is quite significant as it essentially means Web Workers can scale vertically. Considering the inevitable proliferation of multi-core desktop and mobile devices, this is certainly something that will prove advantageous.

Web Sockets API

Web Sockets provide native, full-duplex communications channels which operate over a single socket that enables HTML5 compliant browsers to use the WebSocket protocol (exposed via a JavaScript API) for two-way communication with a remote host.

If you are interested in learning more about each of these technologies I recommend the following resources:

Moving forward, I plan to go into further detail for each of these associated HTML5 Family technologies, providing working examples and detailed information as to how each can be utilized to create some very unique and interesting possibilities on the Web.

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