-----Original Message-----
From: Frank W. Zammetti [mailto:[EMAIL PROTECTED]
Sent: 04 December 2005 04:18
To: Sonali Kulkarni; Struts User
Subject: Re: Integrating Struts in DWR??
Sorry about that, I obviously screwed up in QC... the latest build of
AjaxChat IS NOT A PROPER WEBAPP. My build script is obviously not
working right as far as the distro task goes, and I didn't notice.
Please use the v1.0 alpha, NOT alpha2, which is, AFAIK, correct. It
does have some bugs, but they shouldn't bother you if you are just
checking the AJAX stuff out.
I will correct the latest version tomorrow and cut a new
release... it
is ready to be called 1.0 GA at this point anyway, so it's
just as well.
Alternatively, you could check out from CVS HEAD right now, which
should work fine, but you'll have to compile first.
Frank
Sonali Kulkarni wrote:
Hi Frank,
I downloaded ajaxchat.zip from
link
http://sourceforge.net/project/showfiles.php?group_id=49385&pa
ckage_id=171010&release_id=375018
<http://sourceforge.net/project/showfiles.php?group_id=49385&p
ackage_id=171010&release_id=375018>
But I could not find abt jsp files in the zip, Hence cannot run the
application.
I am planning to run it in Tomcat. Where can I get the
complete source code
for the application, that I can run, and study.
Thanks,
Sonali
On 12/3/05, *Frank W. Zammetti* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Some of the questions you ask here are really more for
you to decide...
there aren't any canned answers. That being said, I'll
do my best...
To begin with, I highly suggest checking out the
numerous articles on
AJAX out there to get a firm grasp on what it really
is, and if I may be
so bold, start with my own:
http://www.omnytex.com/articles
This will show one way AJAX can be integrated with
Struts. You can also
check out my AjaxChat example app on the Struts Apps
SourceForge site:
http://struts.sourceforge.net
The short answer is that AJAX, generically, is nothing
but an HTTP
request. As far as whatever is on the server is
concerned, be it a
Struts apps or something else, it doesn't look any
different than any
other request. Well, I suppose more accurately, it
doesn't *have* to
look any different. If you simply pass simple
parameters from the
client and forego XML, then to Struts there's no difference.
If you want to use XML and Struts, then you will at
this point have to
do your own parsing. With Struts 1.3, it would be
trivial to add a
Command to the processing chain to parse an incoming
XML message and
translate it to request parameters... come to think of
it, that exists
already:
http://sourceforge.net/projects/strutsws
Although that's for Web Services, the underlying theory
is identical.
There is a 1.3 version, courtesy of Marco Mistroni, but
you can see my
original version with the customized RP. The same
thing would work
nicely for AJAX, although one can envision other ways
of doing it too.
You could just as well have this function in your
servlet... it's
just a
matter of getting the body content of the HTTP request,
which would be
XML, parsing it and doing what you'd always do. If
this interests you,
have a look at the code in CVS HEAD here:
http://javawebparts.sourceforge.net
I'll probably cut a release this weekend, but the code
in CVS for the
AjaxTags component in the sample app does exactly
that... an AJAX
request is made with XML in the HTTP body, and a
servlet in this case
gets it (via the handy RequestHelpers.getBodyContent()
method) and then
uses Digester to parse it.
Everything I've talked about here is "naked" AJAX,
i.e., without the
help of any particular library. AJAX is really quite
simple, aside
from
a few gotchas, but there are some very robust libraries
that will help
with more than the basics in most cases. They all seem
to have a
slightly different focus from one another, so if you'd
prefer to go that
route, some (of the many!) to look at are:
http://javawebparts.sourceforge.net/javadocs/javawebparts/tagl
ib/ajaxtags/package-summary.html
<http://javawebparts.sourceforge.net/javadocs/javawebparts/tag
lib/ajaxtags/package-summary.html>
This is the AjaxTags component of Java Web Parts...
this is a little
different than the rest in that it makes enabling
specific events very
easy. All it requires is adding custom tags to your page, and
configuring various AJAX events via XML config file.
For instance, if
you want to fire an AJAX event when a <div> is clicked,
and then you
want a function that will populate another <div> from
what the server
returns, this is a trivial exercise with AjaxTags, and
it's all driven
by config file so there is no coding involved, aside
from adding a tag
or two to your page. This is my own creation, so obviously I'll
push it
a little more than the rest, but I truly do believe it
offers something
than most other options do not and you probably should
at least check it
out and see if it meets your needs.
http://dojotoolkit.com/
This is the one people are starting to really get
behind, and from what
I can see there is good reason for it. This is one of
the ones that
will give you more than just AJAX, and that might be
very appealing
to you.
DWR of course you already know about.
http://prototype.conio.net/
Prototype is actually more of a foundation as there are
other libraries
that use it. So certainly check out some of those
libraries, but
Prototype on its own might be something you want to use.
There is no canonical answer at present for integrating
with Struts, but
the point is there probably doesn't ever have to be
one... it's just an
HTTP request. Oh, there could be something added to
Struts to handle
automatic parsing of XML and stuffing it into an
ActionForm, that might
not be a bad idea, but since you have access to the
request object
anyway in an Action, you can do everything that Struts
would ever do
for
you so it would probably be unnecessary to add it to Struts.
To the question of whether AJAX is appropriate or
not... first, from a
security standpoint, AJAX is no different from every
form you submit,
every window.location call you make, every image you
GET, etc. The same
security concerns that arise in those instances are
present with AJAX.
AJAX has a limitation in that it can't make requests to
domains other
than the one that served the page it's on, so in a
sense it's MORE
secure. But the bottom line is you secure AJAX the
same way you secure
your webapps generally.
If your wondering if it's worth it, that of course is
for you to answer.
There are some cases where it absolutely makes things
better, but it
comes with some baggage... unless you spend a lot of
time worrying about
graceful degredation, your app will now *require*
scripting. This might
not be a problem for you, but it might be. AJAX is
also a problem for
accessability. In some cases this is a major problem,
but even when
it's not it's something we should all think about. It
also raises the
level of expertise your app requires to maintain.
I'm personally a fan of AJAX. I've been doing AJAX for
over 5 years
(keep in mind that AJAX is really more a philosophy and
an approach than
it is any specific technology... I haven't used
XMLHttpRequest for very
long, but I accomplished the same types of things in an
app 5 years
ago). I believe the age of the "classic" web, where
scripting is
optional and apps redraw entire screens, is dead. AJAX
itself is
nothing knew, but the mindset that accompanies it
largely is, so if
your
asking *me* if its a good idea in the first place, I'd
say absolutely
yes, assuming two things... first, that the way you
want to apply it
makes sense; anything can be used in a pointless way of
course!, and
second, that you understand and can accept all the
caveats that go along
with it.
Hope that helps!
Frank
Sonali Kulkarni wrote:
> So, does it mean that is it not a good idea to use DWR with
Struts just as
> yet?
>
> If so, what would be the best way to integrate AJAX
into our Struts
> application?
>
> Ours is a full-blown *financial* banking Struts application.
Please also let
> me know if it is a good idea to use AJAX in the first place,
considering (1)
> the security risks imposed, especially for a financial
application (2) ease
> of integrating AJAX with Struts. (some of the
questions i have,
for starters
> are... how do i pass the request object from the
javascript to my
action
> class method, ... how do i handle errors returned etc)
>
> Thanks for your time! Any replies would be appreciated!
>
>
> On 12/3/05, Frank W. Zammetti < [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
>
>>From the DWR web site:
>>
>>http://getahead.ltd.uk/dwr/server/struts
>>
>>Just reading through it quickly, that's just about
what I would have
>>suggested too in terms of separating out core logic
from Actions and
>>letting your Actions and DWR servlet call them as
needed. There
might
>>be some better approaches, but it sounds like the DWR team is
looking
>>for those approaches themselves.
>>
>>Frank
>>
>>Sonali Kulkarni wrote:
>>
>>>Please suggest if there are any good links, or some
working examples
>>
>>that
>>
>>>explain how Struts could be integrated into the DWR (AJAX)
framework.
>>
>>Any
>>
>>>help would be appreciated. There is hardly any
online support or
>>>documentation.
>>>
>>>Thanks!
>>>
>>
