Reading .js file into JSP code

[Iain Downie]

Anyone out there know of an easy way to fill a Java ArrayList in a JSP from
an
array of strings held in a external JavaScript file? We need to load up a
large number of strings into the page and manipulate with JSP, and feel that
the best way is for the users to have the bulk of the text 'cached' on their
machine in a .js file rather than read from a database every time they
access. The strings will rarely change.

If not, any other better suggestions for cutting the speed of download?

Thanks
Iain

--

_______________ _______________ _______________ ______________
Dr Iain Downie
Web Software Developer, British Trust for Ornithology, The Nunnery,
Thetford, Norfolk IP24 2PU, UK ® Charity No. 216652
Tel: +44 (0)1842 750050, fax: +44 (0)1842 750030 Iain.Downie@bto .org

BirdWeb Gateway: http://www.bto.org/birdweb

[Andrew Thompson]

Re: Reading .js file into JSP code

On Tue, 29 Jun 2004 15:17:25 +0100, Iain Downie wrote:
[color=blue]
> Anyone out there know of an easy way to fill a Java ArrayList
> in a JSP ...[/color]

On the server. Not so much the 'easy' way,
as the 'only' way.
[color=blue]
> ...from an array of strings held in a external JavaScript file?[/color]

If that JS file was on the server,
you could load it and parse it for
the strings, but the *easy* way is
to define the strings as Java Strings
in the JSP, or define the ArrayList
itself in the JSP.

*Whatever* you are trying to achieve,
you are going about it the completely
wrong way.

--
Andrew Thompson
http://www.PhySci.org/ Open-source software suite
http://www.PhySci.org/codes/ Web & IT Help
http://www.1point1C.org/ Science & Technology

[Iain Downie]

Re: Reading .js file into JSP code

After quite a bit of searching, I'm inclined to agree that this is pretty
much impossible, as JavaScript is client and JSP server-side. What I am
trying to *achieve* is get the strings in a file that is as fast as possible
to use, and I thought having that cached on the clients machine would be
best - now know otherwise.

I think I'll have to follow your suggestion and find some way to predefine
the list of strings in JSP, but without constant calls to the database.

Thanks
Iain

"Andrew Thompson" <SeeMySites@www .invalid> wrote in message
news:8t2iar8bcz hc.1c2cce58h4xh o$.dlg@40tude.n et...[color=blue]
> On Tue, 29 Jun 2004 15:17:25 +0100, Iain Downie wrote:
>[color=green]
> > Anyone out there know of an easy way to fill a Java ArrayList
> > in a JSP ...[/color]
>
> On the server. Not so much the 'easy' way,
> as the 'only' way.
>[color=green]
> > ...from an array of strings held in a external JavaScript file?[/color]
>
> If that JS file was on the server,
> you could load it and parse it for
> the strings, but the *easy* way is
> to define the strings as Java Strings
> in the JSP, or define the ArrayList
> itself in the JSP.
>
> *Whatever* you are trying to achieve,
> you are going about it the completely
> wrong way.
>
> --
> Andrew Thompson
> http://www.PhySci.org/ Open-source software suite
> http://www.PhySci.org/codes/ Web & IT Help
> http://www.1point1C.org/ Science & Technology[/color]

[Grant Wagner]

Re: Reading .js file into JSP code

Iain Downie wrote:
[color=blue]
> Anyone out there know of an easy way to fill a Java ArrayList in a JSP from
> an
> array of strings held in a external JavaScript file? We need to load up a
> large number of strings into the page and manipulate with JSP, and feel that
> the best way is for the users to have the bulk of the text 'cached' on their
> machine in a .js file rather than read from a database every time they
> access. The strings will rarely change.
>
> If not, any other better suggestions for cutting the speed of download?
>
> Thanks
> Iain[/color]

Of course this is possible. Given the understanding that a JSP generates HTML
dynamically, it isn't too much of a stretch to understand it can generate
Javascript dynamically as well. So your starting point is:

<script type="text/javascript"
src="somethingT hatMakesAJavasc riptArray.jsp"> </script>

Then somethingThatMa kesAJavascriptA rray.jsp would read the database and generate
code that resembles:

var yourArray = [
"value1",
"value2",
"value3"
// etc
];

Doing this in server-side Javascript would be something like:

<%
// do the database retrieval into resultSet here complete
// with error checking; if resultSet is properly populated
// then proceed with the code below
Response.write( 'var yourArray = [\n');
var lastIndex = resultSet.rows - 1;
for (var i = 0; i < resultSet.rows; i++) {
resultSet.curso r = i;
Response.write( '\t"' + resultSet.theCo lumn + '"');
if (i < lastIndex) {
Response.write( ',');
}
}
Response.write( '];');
%>

But depending on the amount of data involved, downloading this huge array to the
client might not be such a wise idea. Not to mention once the data is "cached"
in a client-side Javascript array, it can't be manipulated by JSP, it has to be
managed by client-side Javascript, something that might be problematic if you're
supporting multiple browsers.

--
| Grant Wagner <gwagner@agrico reunited.com>

* Client-side Javascript and Netscape 4 DOM Reference available at:
*

http://devedge.netscape.com/library/manuals/2000/javascript/1.3/reference/frames.html

* Internet Explorer DOM Reference available at:
*

http://msdn.microsoft.com/workshop/author/dhtml/reference/dhtml_reference_entry.asp

* Netscape 6/7 DOM Reference available at:
* http://www.mozilla.org/docs/dom/domref/
* Tips for upgrading JavaScript for Netscape 7 / Mozilla
* http://www.mozilla.org/docs/web-deve...upgrade_2.html

[kaeli]

Re: Reading .js file into JSP code

In article <cbs1jg$2h1$1$8 302bc10@news.de mon.co.uk>, iain.downie@bto .org
enlightened us with...[color=blue]
> After quite a bit of searching, I'm inclined to agree that this is pretty
> much impossible, as JavaScript is client and JSP server-side. What I am
> trying to *achieve* is get the strings in a file that is as fast as possible
> to use, and I thought having that cached on the clients machine would be
> best - now know otherwise.
>
> I think I'll have to follow your suggestion and find some way to predefine
> the list of strings in JSP, but without constant calls to the database.
>[/color]

Why don't you just use an include file?
Same thing as the JS file concept, but all on the server.
JSP has an include directive.

--
--
~kaeli~
Going to church doesn't make you a Christian any more than
standing in a garage makes you a car.

http://www.ipwebdesign.net/wildAtHeart

http://www.ipwebdesign.net/kaelisSpace

[Iain Downie]

Re: Reading .js file into JSP code


"kaeli" <tiny_one@NOSPA M.comcast.net> wrote in message
news:MPG.1b4b9e 117595fe48989f4 1@nntp.lucent.c om...
[color=blue]
> Why don't you just use an include file?
> Same thing as the JS file concept, but all on the server.
> JSP has an include directive.[/color]

I thought about that, and yes it is possible, but what advantages in
download speed would there be? The original idea was the huge array of
strings would have been held on the clients machine and thus not need as
much download. An include file would always have to be recalled when the JSP
is turned into HTML. The only advantage I can see with includes (in this
case) would be easier coding and a single instance that I can update when
required.

Thanks
Iain

[Andrew Thompson]

Re: Reading .js file into JSP code

On Wed, 30 Jun 2004 08:41:56 +0100, Iain Downie wrote:[color=blue]
> "kaeli" <tiny_one@NOSPA M.comcast.net> wrote in message[/color]
...[color=blue][color=green]
>> Why don't you just use an include file?
>> Same thing as the JS file concept, but all on the server.
>> JSP has an include directive.[/color]
>
> I thought about that, and yes it is possible, but what advantages in
> download speed would there be? The original idea was the huge array of
> strings would have been held on the clients machine and thus not need as
> much download.[/color]

We have now determined that what you wish to
achieve cannot be done with JS, so this thread
should be continued elsewhere.

I will give you a parting thought though.
A signed Java applet can store data on the
client for quick access..

If you choose to use an applet, I suggest you
make a 'follow-up' to this post, but direct
it straight to c.l.java.progra mmer.

HTH

--
Andrew Thompson
http://www.PhySci.org/ Open-source software suite
http://www.PhySci.org/codes/ Web & IT Help
http://www.1point1C.org/ Science & Technology

[Thomas 'PointedEars' Lahn]

Re: Reading .js file into JSP code

Iain Downie wrote:[color=blue]
> After quite a bit of searching, I'm inclined to agree that this is pretty
> much impossible, as JavaScript is client [...]-side. [...][/color]

No, J(ava)Script is a script language. It can be used both client-
and server-side, provided that you have an appropriate server.


PointedEars