How will caching be controlled
It's possible that an XMLHttpRequest response will be cached by the browser. Sometimes, that's what you want and sometimes it's not, so you need to exert some control over caching. With cache control, we're talking about GET-based requests. Use GET for read-only queries and other request types for operations that affect server state. If you use POST to get information, that information usually won't be cached. Likewise, if you use GET to change state, you run the risk that the call won't always...
Event Handling Behind the Scenes
If you've not worked with a modern user interface framework such as Java's Swing, you might wonder how JavaScript events work. The answer is that, behind the scenes, the operating system tells the browser what the user's doing, and the browser then passes this information to the script. For instance, the operating systemmonitoring keyboard and mouse inputmight notice that the user hit X while the keyboard focus was on the browser window. It will then notify the browser, and the browser will...
Lace
Lace Chat http socket7.net lace handles Periodic Refreshes to show all users' chat messages. The timer is set on startup to periodically call the get function, which initiates theXMLHttpRequest Call Chapter 6 for new messages this.timerlD setlnterval function thisObj.get true , interval get performs a straightforward query of the server this.httpGetObj.open 'POST', this.url, true charset UTF-8' this.httpGetObj.onreadystatechange function thisObj.handleGet system this.httpGetObj.send pa ram If...
Code Example HTMLHttpRequest Library
HTMLHttpRequest is a cross-browser remoting component. It works by wrapping around a real, concrete remoting objecteither an xMLHttpRequest object or aniFrame, only one of which will be set. The construction code below makes extensive use of feature-dependent behavior to decide, at each stage, whether to proceed with a particular strategy. There is also some use of feature-dependent behavior to ensure that Opera and IE5 don't follow a particular path. function HTMLHttpRequest myName,callback...
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JSON Message
JSON Messages see later in this chapter are being used by several Ajax Stub frameworks because Ajax Stubs need to share data between browser and server i.e., inbound arguments and outbound return values. These objects should be standard JavaScript objects in the browser and standard Java or PHP or whatever-your-language-choice objects on the server. In between, it's most convenient to transfer them as strings. JSON defines a standard way to convert objects in many languages to and from a string...
Constraints on external domains
On discovering XMLHttpRequest, a common reaction is to start dreaming up an interface that pulls in content from popular web sites and mashes it altogether to into one big Web 2.0 souffl . Unfortunately, it's not so simple because of a key security rule imposed by all major browsers XMLHttpRequest can only access content from the originating server. If your application lives atittp aiax.shop admin, then your XMLHttpRequest objects can happily and shouldn't be able to reach http books.aiax.shop...
Solution Iph
Track XMLHttpRequest calls as they proceed from browser to server and back again. xMLHttpRequest is a fairly basic component that needs to be augmented or wrapped for better control over asynchronous dialogue. Furthermore, it is useful to keep all these wrappers in a collection. Note that this pattern is fairly low level, and the details should generally be encapsulated in a wrapper library. The standard mechanism for Call Tracking requires an XMLHttpRequest wrapper. Consider the implementation...
A AnthemNETforASPNET x
Anthem.NET is Jason Diamonds' new version of a long-established Ajax library, now a SourceForge open source project. Athem.NET provides a set of Ajax-enabled controls inherited from ASP.NET server controls, with most Ajax behaviors pre-built, avoiding lots of client JavaScript. It supports Viewstate so that you can actually modify server controls either Anthem controls or ASP.NET controls inside an Anthem controle.g., panel in your server-side code, in C or VB without having to mess about in...
Google Suggest
Google Suggest http www.google.com webhp complete 1 features Suggestions, so when you type A, the browser pops up a list of popular searches beginning with A. To prevent against excessive queries, Google Suggest uses Submission Throttling. Zuggest is a Live Search Chapter 14 showing Amazon results as you type Figure 10-5 . So type Ab and you'll get results like Basic Ab Workout for Dummies and Absolutely Fabulous. The results are images as well as text, so it would be expensive to search for...
RealWorld Examples Nxt
Frederico Caldeira Knabben's FCKEditor http www.fckeditor.net is a feature-rich, open source Cross-Browser Component you can pull into your own projects Figure 14-15 . It also has some server-side integration and web remoting support. m - ' ' - - --- rt-wvy i tktiL t i .ritt T lt JCt Cam -nAimi, Lntiifii 4r mill WML licK pi v m wi LjhiIIV he .r ii hy Onfc gt H ft fldi - Mftl frtdtrd Cikk-ia K lei All i -Vi 14.5.5.2. Jotspot, Dojo Rich Text Editor Jotspot is a wiki host that allows editing in...
Ajax Patterns Demos
The Ajax Patterns Demos appear in many patterns as Refactoring Illustrations and also in the Solution section. They're all online at http aiaxifv.com run , and it would be worth trying them out. In addition, the full code base can be downloaded from that location its installation is explained in the Appendix B. It includes the demos as well as completed code foChapter 2. Note the demos have been tested on Firefox 1.5 and IE6, though most of them work on comparable browsers as well. The...
A JavaScript Object Notation JSON and JSONRPC
JSON is a fat-free XML alternative and JSON-RPC http www.ison-rpc.org is a remote procedure protocol, akin to XML-RPC, with strong support for JavaScript clients. See JSON Message Chapter 9 . Implementations http www.json-rpc.org impl.xhtml exist for several server-side platforms such as Java, Python, Ruby, or This document was created by an unregistered ChmMagic, please go to http www.bisenter.com to register it. Thanks Perl. Individual packages and licenses for each platform. Original concept...
A AjaxCaller from May
AjaxCaller is a basic, threadsafe wrapper around XMLHttpRequest that is mainly for Ajax newcomers packaged with the Ajax Patterns demos. See TestAjaxCaller RESTful calls to the server GET POST PUT DELETE with plain-text or XML routed to a callback operation Aimed at Ajax newcomersinstead of optimizing performance or footprint, the library aims to be a readable code base and provides debugging support Open source license Creative Commons by Michael Mahemoff http softwareas.com , with some ideas...
Code Example FCKEditor
This example introduces the FCKEditor API and looks at some of the internals. To use FCKEditor in your own project, first create a regular textarea lt textarea FCKEditor can then replace the text editor with a rich editor var commentsEditor new FCKeditor comments commentsEditor. ReplaceTextarea To track usage, register an initialization handler for the global FCKEditor module, which applies to all editor instances. Here you probably want to set up an event handler that will fire when a user...
Metaphor Xrh
Think of a physical templatea document with most content already present, with a few blanks to populate with current values. Chapter 12. Code Generation and Reuse THERE ARE TWO GENERAL PROGRAMMING PATTERNS IN THIS CHAPTER. SERVER-SIDE CODE GENERATION IS one technique people are using to avoid working directly with HTML and JavaScript. Cross-Browser Component is a component that's been developed for portability across the major browsers.
Backbase Portal
The Backbase Portal Demo contains a page full of Portlets Chapter 15 arranged in three columns, each with its own menu. The menu contains all of the Portlets on the page, and choosing a Portlet causes it to move over to the top of the column. One-Second Motion is used to animate the Portlet's movement, allowing users to see that thePortlet has flown in to the top of a column from elsewhere on the page.
Code Refactoring AjaxPatterns Unique URL Sum
This example refactors the Basic Sum Demo http ajaxify.com run sum using both the Page-URL and IFrame-URL techniques. There are actually four implementations here Unique URL Sum Demo http ajaxify.com run sum uniqueURL uses the Page-URL technique so that when state changes, the URL will change. Polling URL Sum Demo enhances the Unique URL Sum Demo by adding a polling mechanism, so that when the URL changes, the state will also change. Thus, the URL-state synchronization occurs in IFrame URL Sum...
Code Example AjaxPatterns TestAjaxCaller
The example referenced in the Solution, earlier, covers most typicalxMLHttpRequest usage. In practice, many people adopt Ajax frameworks and libraries rather than calling XMLHttpRequest directly. That's the approach taken with all of the Ajax Patterns demos, which use a library called ajaxCaller.js that was developed in parallel to the demos themselves. It's a fairly basic library, but offers a simple interface for the functionality that's typically required of XMLHttpRequest. In this section,...
Chapter Display Manipulation
FOR AN END USER, THE MOST OBVIOUS THING ABOUT AJAX IS ITS VISUAL APPEARANCE. AJAX APPS TEND to look richer, and the interface tends to update smoothly, more like a desktop app than a conventional web app. This chapter describes the two main technologies for updating the user interface. Display Morphing focuses on changes to a single element, whilePage Rearrangement involves changes to the page structure. Along the way, we'll look at the Document Object Model DOM . DOM manipulation is key to...
Detecting errors
Sometimes, a request doesn't come back as you expected it, or maybe not at all. You scripted the call wrong, or there's a bug in the server, or some part of the infrastructure just screwed up. Thinking asynchronously is the first step to dealing with these problems, because at least your application isn't blocked. But you need to do more than that. To detect a server error, you can check the response status using xMLHttpRequest'sstatus flag. This is just a standard HTTP code. For example, if...