Can you write REAL applications with AJAX?

Phil Sarin Advanced UI Software April 15, 2009

Problem: Many web apps stink

Rich Internet Applications (RIAs) • • • Easy deployment and maintenance “Desktop-like” interactivity Willing to sacrifice some “webness” (e.g., bookmarks)

RIA Approaches • • Browser plug-in ▫ Flash/Flex, Java Swing, Silverlight ▫ Potentially greater interactivity, higher barrier to adoption ▫ Concerns about openness/control In browser, no plug-ins ▫ AJAX ▫ Lower barrier to adoption ▫ Cross-browser mayhem?

Questions for today • • • Can we approach AJAX development like “regular” GUI development?

What are the approaches/tradeoffs?

What’s likely to become popular?

What is AJAX?

What is AJAX?

AJAX event handling

Some History

History: Hill Climbing

RIA: Which hill to climb?

Approaching RIAs from two hills

HTTP

Origins in early web sites Built around the HTTP protocol Generating HTML

Direct Manipulation

Origins in desktop GUIs Built around user events Laying out graphical objects

The HTTP Hill

The HTTP Hill

Static Pages

• • • Server fetches and returns a web page Initially just text-based With Mosaic, pictures too

The HTTP Hill

Dynamic Pages

• • Server-side ▫ CGI (mostly perl) Client-side ▫ Javascript

The HTTP Hill

“Frameworks”

• • • • MVC support (Struts 1 & 2, Rails, Django) Easier HTML generation (JSP, ERB, Freemarker, …) State/sessions Javascript libraries (Prototype, DOJO, jQuery)

The HTTP Hill

Pros/Cons (prior to AJAX)

+ + + Very cheap for simple sites Reasonably flexible ▫ Mail clients!

Web-friendly ▫ Bookmarkable ▫ Indexable Slow feedback Minimal interactivity Cross-browser mayhem

The Direct Manipulation Hill

The Direct Manipulation Hill

The Direct Manipulation Hill

GUI Toolkits

• • Common widget set across applications Standalone or client-server

The Direct Manipulation Hill for Internet applications

Browser Plug-Ins

• • Flash, Java, Silverlight Took a long time to catch on

The Direct Manipulation Hill

Pros/Cons

+ + + + Timely feedback Programming power (behaviors, constraints – at least possible) Common widgets (consistency, usability) Flash/etc: more consistent runtime platform Flash/etc: needs a plug-in Cross-platform issues still exist Proprietary runtime platform

Where does AJAX fit in?

Where does AJAX fit in?

Both hills!

AJAX on the HTTP Hill • • • • • Tactical features ▫ Autocomplete ▫ Drag and drop AJAX-aware code ▫ Raw Javascript/HTML/CSS ▫ Or with a library Okay for some applications Too limiting for RIAs Not the focus of this talk

Direct Manipulation AJAX

AJAX on the Direct Manipulation Hill • • • • Separate development environment from runtime environment.

Runtime environment: HTML/Javascript/CSS (AJAX) Development environment: toolkit in another language Two approaches: thin and fat

Thin Client AJAX Approach

Example: Google Maps (pretend it’s a thin client app)

A Grid of Images

Example: Google Maps

Sequence

Thin Client Pros and Cons + Simple programming: ignore the network + All your code runs server-side + Programmers love it!

+ Undo, behaviors, constraints: all possible!

Scalability (server-side state, lots of requests) Slow feedback: network hop for each user action

Fat Client AJAX Approach

Example: Google Maps

Sequence

Wait a second… • • No AJAX calls involved in moving the map around!

▫ Mostly Javascript.

▫ New image requests are synchronous Example AJAX call: adding an intermediate destination

Fat Client Pros and Cons + Scalable (client-side state, fewer HTTP calls) + Fast feedback + Undo, behaviors, constraints possible… …but undo more complex than on the desktop More complicated: network-aware, distributed

Example AJAX Toolkits • • • • Google Web Toolkit: Fat Client ▫ Write in Java, compiled to Javascript Cappuccino: Fat Client Echo2: Thin Client ▫ Write in Java ▫ No HTML/CSS (proprietary stylesheet language) Echo3 (Java – Beta): hybrid ▫ Thin widgets in Java ▫ Fat widgets in Javascript

So, is AJAX viable for RIAs?

Fat AJAX Thin AJAX

Feedback Speed

Winner (tied) Plugin (Flash, Swing) Winner (tied)

Interactive Potential Scalability Cross-platform Consistency Momentum Ease of Programming

Winner (tied)

Google does a lot of work for you.

?

Winner Winner Winner (tied) Winner

Adobe does a lot of work for you.

Thin vs Fat AJAX?

• • Thin AJAX: Squeezed out ▫ Insufficient if interactivity matters ▫ Not as easy as an HTTP-oriented application Fat AJAX: How does it compare to plug ins?

▫ Developer adoption?

▫ Application philosophy?

Some Toolkits

GWT: A Toolkit… • • Laying out widgets in a container “panel” Events and handlers // Create a Horizontal Panel HorizontalPanel hPanel = new HorizontalPanel(); // Leave some room between the widgets hPanel.setSpacing(5); // Add some content to the panel for (int i = 1; i < 5; i++) { hPanel.add(new Button("Button " + i)); } http://code.google.com/webtoolkit/doc/1.6/DevGu ideUserInterface.html

…with non-strict abstractions • • • • Styling with CSS Directly embed Javascript Raw HTML Direct DOM manipulation private native void putElementLinkIDsInList(Element elt, ArrayList list) /*-{ var links = elt.getElementsByTagName("a"); for (var i = 0; i < links.length; i++ ) { var link = links.item(i); link.id = ("uid-a-" + i); [email protected]::add(Ljava/lang/Objec t;) (link.id); } }-*/; http://code.google.com/webtoolkit/doc/1.6/DevGu ideUserInterface.html

Cappuccino: A different philosophy “When you program in Cappuccino, you don't need to concern yourself with the complexities of traditional web technologies like HTML, CSS, or even the DOM. The unpleasantries of building complex cross browser applications are abstracted away for you.” http://cappuccino.org/learn/

Javascript as “assembly language” http://280slides.com

Cappuccino vs GWT • • • Philosophical question GWT: RIAs that are part of of the web Cappuccino: RIAs deployed over the web ▫ Alternative to Flash/Flex

Finally

Recommendations • • • • If you’re serious about RIAs, climb the direct manipulation hill.

Don’t limit yourself to Thin AJAX.

AJAX sweet spot: Applications that are part of the web.

AJAX is an implementation alternative for applications deployed over the web.

References 1 adaptive path » ajax: a new approach to web applications. (n.d.). . Retrieved April 8, 2009, from http://www.adaptivepath.com/ideas/essays/archives/000385.php

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Adobe wants to be the Microsoft of the Web at Ted Leung on the Air. (n.d.). . Retrieved April 8, 2009, from http://www.sauria.com/blog/2007/03/01/adobe wants-to-be-the-microsoft-of-the-web/ .

Cappuccino Web Framework - Build Desktop Class Applications in Objective-J and JavaScript. (n.d.). . Retrieved April 15, 2009, from http://cappuccino.org/ .

Comparing the Google Web Toolkit to Echo2. (n.d.). . Retrieved April 9, 2009, from http://www.theserverside.com/news/thread.tss?thread_id=40804 .

References 2 Dare Obasanjo aka Carnage4Life - What Comes After AJAX? (n.d.). . Retrieved April 8, 2009, from http://www.25hoursaday.com/weblog/PermaLink.aspx?guid=11c471d6-ea65 4ed2-b387-c9ec966d8418 .

Developer's Guide - Google Web Toolkit - Google Code. (n.d.). . Retrieved April 9, 2009, from http://code.google.com/webtoolkit/doc/1.6/DevGuide.html

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Echo2 Technical Overview | Echo Web Framework. (n.d.). . Retrieved April 8, 2009, from http://echo.nextapp.com/site/echo2/doc/tov .

Echo2 Tutorial | Echo Web Framework. (n.d.). . Retrieved April 8, 2009, from http://echo.nextapp.com/site/echo2/doc/tutorial.

References 3 Echo2 versus GWT • The Register. (n.d.). . Retrieved April 9, 2009, from http://www.theregister.co.uk/2006/08/24/echo2_framework/ .

Feigin, B. (n.d.). Cappuccino and Objective-J. Retrieved from http://www.cs.cmu.edu/~bam/uicourse/830spring09/Benjamin%20Feigin%20 %20Cappuccino.pptx

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Following up on “The Microsoft of the Web” at Ted Leung on the Air. (n.d.). . Retrieved April 8, 2009, from http://www.sauria.com/blog/2007/03/04/following up-on-the-microsoft-of-the-web/ .

LaszloWhitePaper.pdf. (n.d.). . Retrieved April 8, 2009, from http://www.openlaszlo.org/whitepaper/LaszloWhitePaper.pdf.

References 4 Mesbah, A., & van Deursen, A. (2006). An Architectural Style for Ajax. cs/0608111. Retrieved April 8, 2009, from http://arxiv.org/abs/cs/0608111.Tony C Shan, & Winnie W Hua. (2006).

Taxonomy of Java Web Application Frameworks. In

e-Business Engineering, 2006. ICEBE '06. IEEE International Conference on (pp. 378-385). doi: 10.1109/ICEBE.2006.98.