1. Ajax and Your CMS -- CMS Watch 页码，1/5
Direct Web Remoting
Ajax and Your CMS
by Jonathan Downes and Joe Walker
03-Apr-2006
If a modern day Rip van Winkle woke up after just a year's sleep, he
would be stunned by the buzz around Ajax today. Technology is
moving very quickly in this space and whether you are a web author,
a CMS developer, or a regular web user, Ajax will make some exciting
changes to your world. (We'll assume you already know about Ajax; if
not, read this introductory primer.)
For the Web CMS world, Ajax offers the possibility for a better user
experience for content authors as well as site visitors. But what of its
limitations? While Ajax delivers many benefits, it also creates a few
challenges. This article will look at some of the benefits and
limitations of Ajax for managing web content.
2 Sides to Ajax in your CMS
Fundamentally, there are two dimensions to examining Ajax and your content
management system.
Ajax in my CMS Interface: Firstly, how is my CMS Vendor applying Ajax to improve
their CMS product to benefit authors and site managers? To the extent that Ajax can
afford a potentially more familiar, desktop feel to a web-based application, this is the
area we would expect most of their attention to be focused at the moment. And
indeed, many vendors are working on Ajax-driven interfaces for their products.
CMS support for creating Ajax-driven web sites: Secondly, what tools is my CMS
vendor providing me with to include Ajax in the sites I produce for my customers?
This area may come later but is vitally important. As Ajax interfaces become
commonplace, your team will want to look at providing them to your customers. It is
one thing to have a greatly improved user interface on your CMS tool, but you do not
want to lose web traffic and sales because your websites have fallen behind on
usability.
What opportunities does Ajax afford?
Single-Page Interface: One of the great things about Ajax is that you don't need a
page refresh every time you want to add some more information to the page. This is
sometimes referred to as a "Single-Page Interface" and is particularly useful where a
large data set is required behind the scenes to enable a function. For example, CMS
vendor Day has long made use of Ajax for their tree navigation, overcoming many of
the technical and graphical challenges with the traditional approach (see screen
below). For example maintaining the state of which branches of the tree are open and
which are closed is very difficult with standard HTML, and is also very inefficient on
the network.
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2. Ajax and Your CMS -- CMS Watch 页码，2/5
Day's expandable nav tree (click to enlarge)
CMS vendor Mediasurface uses Ajax for presenting context-sensitive information. The
screens below illustrate what happens when the 'Edit Item Details' task is selected.
The toolbar, menu bar and task pane on the right are updated directly within the
browser window to present the editor with additional information, the appropriate edit
boxes, and a revised set of options.
Click to enlarge
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3. Ajax and Your CMS -- CMS Watch 页码，3/5
Click to enlarge
Ajax has been successfully used for in line spell checking on the web, and can work
well for auto completion of meta data in a manner similar to Google's Googlesuggest.
Editors will like the fact that they can save changes without the need for a full
"submit," which might generate a new version or prematurely kick off a workflow with
an unnecessary e-mail to somebody. As an approach, Ajax supersedes the frames
approach -- still common in many DM and CM systems -- to providing subparts of an
interface that can be managed independently.
Drag and drop: Ajax has brought with it a seemingly infinite increase in the amount
of information available for the page designer to present to the user. Consequently
there has been a revival and acceleration in the development of web user interface
tools and techniques. One notable opportunity for the content management
applications is the use of drag-and-drop for positioning and ordering of content on a
page, again traditionally the realm of the desktop application. Examples of this type
of interface in action include customising news layout in google news and gadget
layout on Microsoft's live.com. Also Scriptaculous offers some very interesting demos.
Better Performance: This covers a range of issues, but in general Ajax provides a
faster update of page content than does full page refreshing. Since the server is
sending data and not full pages, response times improve, and with layout changes
reflected at the client, the overall load on the server is reduced (although this needs
to be balanced off with the increase in the number of requests being made back to
the server). For authors, this can mean a snappier experience within the tool ?never
a bad thing - and likewise, improve the performance of a CMS-driven site that would
otherwise serve entire pages dynamically.
Nevertheless, it is worth being aware of the user perception issue. If authors can't
see anything happening, they will think that nothing is happening. Ironically, a visible
but slower full page refresh maybe perceived as more responsive than a sub page
update. Inserting the word "loading" or similar while data is being retrieved can really
assist here.
Manage Ajax-enabled snippets: If you are going to use a heavily-Ajax-driven
interface on your websites, then it is worth considering a CMS to manage intra-page
snippets and interaction as discrete elements. In practice it could be difficult to
manage a rich, interactive site that uses single page interfaces without a CMS, since
at this point you are managing content components rather than entire "pages." The
whole notion of "pages" tends to dissipate, which would call for a more component-
oriented -- rather than page-oriented -- CMS for those looking to manage Ajax-driven
websites.
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Manage DHTML/JavaScript components: Starting a large Ajax website from
scratch can certainly make extra work for a skilled JavaScript developer, so there is a
great benefit from building on someone else's work. The Dojo library stands out as an
excellent cross-platform Ajax toolkit, while DWR for Java and SAjax for PHP are
capable libraries with extensive server-side integration. The key question for your
CMS is: how will it manage these components? Web CMS tools are notoriously poor at
managing stylesheet elements and client-side scripting in particular. The rise of Ajax
should prompt some improvements here.
What are the potential drawbacks for the Web Author?
Back Button & Bookmarks: "Single Page" interfaces complicate the relationship
between the URL and the content in the page. Consequently you break two traditional
web expectations, the back button and the bookmark. A number of vendors deal with
this by removing the traditional web buttons from the Ajax user interface. Here the
desktop concept of undo becomes much more relevant and the vendor can more
closely control the navigation of the user within the application. To be sure, many
CMS tools today will not support the back button nor persistent URLs within the
application, although in general they are getting better at this, and URLs that can be
embedded in e-mails are increasingly important in a world where information workers
spend much of their day in Outlook.
It is work noting, however, that there are circumstances when a user would not
expect these features to work even in the traditional web world, for example,
pressing the back button after submitting your credit card details does not undo an
online purchase. Likewise, bookmarking the BBC News home page does not return
you to the same content every day.
Refresh: Related to the above issue is the risk that a page refresh part way through
an Ajax sequence will return the user to a page at the beginning of the sequence. For
example, if you are looking at a specific mail on Gmail and press refresh you are
returned to the Inbox. Here again, most CMS tools -- which are essentially forms-
based applications -- already will tend to create unexpected behavior upon manual
page refresh, but Ajax probably aggravates the problem.
Visual Accessibility: This relates to the use of screen readers like Jaws. Readers
that are designed around traditional Multi-Page Interface sites are going to struggle
with an Ajax rich site. It should be noted that most CMS interfaces are already non-
compliant for all sorts of reasons (use of color for meaning, graphical navigation,
etc.), and many vendors are working on separate, accessible interfaces. Ajax will
compound the challenge for vendors and buyers alike. In time we expect that screen
readers will improve to handle more dynamic pages, and CMS vendors will become
better at allowing their pages to integrate with screen readers, but meanwhile this
presents a real challenge.
Security: Ajax doesn't present terribly new or extraordinary security risks since it
employs technologies that have been around for several years, although it is always
possible on a public-facing site to create vulnerabilities through bad code. A bigger
issue may be that security conscious users that have turned JavaScript off will be
more inconvenienced by Ajax websites than conventional ones. Fortunately, the
number of security issues with major browsers is reducing while the web's
dependence on JavaScript is increasing. The combination of these events means that
fewer and fewer users will turn JavaScript off and many will adopt plug-ins that allow
JavaScript from selective sites.
Clearly the impact of any of these issues is reduced if your CMS is all internal-facing.
Many if not most CMS products on the market today employ JavaScript already. See
DWR for a more detailed discussion.
Preview: Authors always want to preview content before publishing it. So how can
your CMS enable them to preview changes to a text snippet that appears only under
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certain circumstances? This challenge is similar to the problem of previewing pages
destined to be published on highly personalized sites. Some vendors provide authors
capabilities to simulate user behavior to confirm where and how modified content will
appear. Publishers of Ajax-driven sites will want the same.
Browser compatibility: Needless to say this is an issue on public sites, but it also
comes into play on the CMS contributor side, where vendors are just now getting a
decent handle on IE quirks and developing FireFox compatibility. Many of the
technologies used by Ajax websites have been around for several years, but have
been largely ignored by web developers. One of the big reasons for this was the
difficulty developers had in making their solutions work in all browsers. Two recent
factors have changed this to a large extent; browsers have become more standards
based, and libraries like DOJO, DWR and SAjax (see above) do a lot to mask the
nuances.
Some of these issues may dissuade you or your vendor from using Ajax aggressively
at the moment, but history would suggest that it is only a matter of time and of
course some creative technical development before suitable solutions or work-
arounds become available. Perhaps Ajax will even provide radically new approaches
and give us better functionality than we thought possible.
On the whole, Ajax is here to stay. It is still early days, but the number of
unanswered questions appears to be more than matched by the growing amounts of
development energy. While at the moment, content management vendors may be
satisfied to experiment with Ajax in their contributor interfaces, their approaches will
rapidly mature. After coming to appreciate Ajax within their CMS tool interfaces,
content managers will be demanding support tools for Ajax in the templates and sites
they themselves publish. It will be interesting to see how quickly the vendors can
respond.
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About the Author
Jonathan Downes is founder of Prokata a growing resource for leaders
navigating their organizations through the world of information
management.
Joe Walker is an Ajax expert and creator of DWR the most popular open
source Ajax framework for Java.
http://www.cmswatch.com/Feature/143-Direct-Web-Remoting?printable=1 2006-4-5