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Ajax Patterns and Best Practices

:	Christian Gross
:	Ajax Patterns and Best Practices
:	Apress
:	9781430201311
:	1
:	CHF 36.00
:

:	Informatik
:	English

:	416
:	Wasserzeichen/DRM
:	PC/MAC/eReader/Tablet
:	PDF

Takes a unique angle on Ajax, providing patterns for application development and best practices for integrating Ajax and REST into rich applications

Designed to suit all groups of developers across many platforms, who are interested in the hot new topic of Ajax

Hi h demand for Ajax knowledge. Leading technology companies like Google and Yahoo are looking for developers with intimate knowledge of Ajax

Chapter 1 Introduction to Ajax (p. 1-2)

Asynchronous JavaScript and XML (Ajax)1 is both something old and something new old because already existing technologies are used, but new because it combines these existing technologies into techniques that very few considered previously. Simply put, because of Ajax a new generation of applications and ideas are bubbling on the developer scene. A very brief definition of Ajax is as follows: Ajax is a technology that complements Web 2.0 and the integration of many web services at once.

This brief definition poses more questions than it answers, as now you are likely wondering what Web 2.0 is and what the integration of many web services are. Web 2.0 can be thought of as the Internet economy.2 Think about something as typical as an encyclopedia, and you will start to think about salespeople who carry extremely heavy books and knock on doors. In a Web 2.0 context, an encyclopedia means Wikipedia (http:// www.wikipedia.org). The Wikipedia project is an open effort by humanity to record itself. Whereas for a traditional encyclopedia a set of writers and editors write about certain topics, Wikipedia is created by people who write about what they know. Get enough people together and you get an encyclopedia that is on the Internet. What is thought-provoking about the Wikipedia project is that anybody can edit it, and therefore it usually contains more current and unusual information than a traditional encyclopedia. In some instances Wikipedia s selfcorrecting capabilities have proven to be problematic, but considering the scale and depth of the project, those instances have been exceptions.

The second part of Ajax is the integration of many web services at once. Ajax allows a higher level of interactivity in a HyperText Markup Language (HTML) page than was possible without Ajax technologies. The result is that an Ajax application changes from a web application to a web service manipulation technology. In a traditional web application, navigating content meant changing HTML pages. With Ajax, navigating content means navigating web services that could be generating HTML content, or Extensible Markup Language (XML) content, or other content.

Pictures Are Worth a Thousand Words

The definition explains Ajax, but you are probably still wondering what Ajax does. There is a saying that a picture is worth a thousand words, and the following images and their associated explanations illustrate best what Ajax does. Map.search.ch was one of the first major Ajax applications, and it illustrates the elegance of what an Ajax application can be. In a nutshell, Map.search.ch is used to find restaurants, houses, parking spots, and more throughout Switzerland. When you surf to the website http://map.search.ch, you will see something similar to Figure 1-1.

	Contents at a Glance	6
	Contents	8
	About the Author	14
	About the Technical Reviewer	16
	Acknowledgments	18
	Introduction	20
	CHAPTER 1 Introduction to Ajax	24
	Pictures Are Worth a Thousand Words	25
	Another Ajax Example	31
	Ajax Architecture Basics	33
	It s About the Data	34
	It s About the Navigation	35
	Comparing Ajax to Other Application Types	37
	Rich-Client Local Installation	37
	Rich-Client Web Services	38
	Plain-Vanilla Web Application	39
	Some Final Thoughts	40
	CHAPTER 2 The Nuts and Bolts of Ajax	42
	Ajax for the Impatient	42
	Understanding REST Theory	42
	Implementing the REST Data	44
	Implementing the Ajax Application	45
	Putting Together Ajax and REST	46
	Understanding the Ramifications of Ajax and REST	47
	XMLHttpRequest Details	48
	Using the Factory Pattern	50
	Defining an XMLHttpRequest Factory	51
	Rewriting the Ajax Application to Use a Factory	52
	Making Asynchronous Requests	53
	Making Practical Use of XMLHttpRequest	57
	Implementing an Asynchronous Calling Mechanism	57
	Calling Domains Other Than the Serving Domain	68
	Some Final Thoughts	74
	CHAPTER 3 Content Chunking Pattern	76
	Intent	76
	Motivation	76
	Applicability	77
	Associated Patterns	78
	Architecture	78
	Implementing Order in a Web Application	78
	Defining the Content Within a Content Chunk	82
	Implementation	83
	Implementing the HTML Framework Page	83
	Injecting Content by Using Dynamic HTML	85
	Binary, URL, and Image Chunking	92
	JavaScript Chunking	95
	Pattern Highlights	100
	CHAPTER 4 Cache Controller Pattern	102
	Intent	102
	Motivation	102
	Applicability	104
	Associated Patterns	105
	Architecture	105
	HTML and HTTP Cache Directives	105
	HTTP Expiration Caching Is a Bad Idea (Generally)	107
	Better Approach: Using HTTP Validation	107
	Some Findings Regarding Server-Side Caching	109
	Defining Static HTTP Validation	111
	Defining Dynamic HTTP Validation	112
	Implementation	114
	Implementing the Passive Cache	114
	Implementing the Server Side of the HTTP Validator	123
	Pattern Highlights	131
	CHAPTER 5 Permutations Pattern	134
	Intent	134
	Motivation	134
	Applicability	139
	Associated Patterns	139
	Architecture	139
	Understanding Why the Resource Is Separated from the Representation	140
	Using Cookies and HTTP Authentication to Authorize Access Only	142
	Using Cookies	145
	An Example Book Application	146
	Implementation	151
	Rewriting URLs	151
	An Example Shopping Cart Application	158
	Pattern Highlights	173
	CHAPTER 6 Decoupled Navigation Pattern	176
	Intent	176
	Motivation	176
	Applicability	180
	Associated Patterns	182
	Architecture	183
	Implementation	185
	Implementing the Action Functionality	185
	Defining and Implementing the Common Data Functionality	195
	Implementing the Presentation Functionality	210
	Using HTML Components	215
	Pattern Highlights	2