AppletTalk.com

Leigh · Guest

I'm building a data entry application using Java servlets.
I had hoped to use drop down boxes to provide the user with
data entry selections pulled from a database into an html
form, but am now questioning, given the latency with which
the data loads to the browser, whether drop down boxes are
viable for providing a large number of select options.

I've put identical examples of the problem on two different
web/database hosts for review (I wanted to test on different
hosts to rule out a problem with the database server and the
web/tomcat server). One host uses SQL Server and Tomcat 3x,
the other is using PostgreSQL 7.23 and Tomcat 4.124. I'd
appreciate anyone who could take a look at these examples
and comment on whether what I'm trying to do via drop down
boxes seems feasible, and if not, well, suggestions on another
tack would be welcome.

Here are the two examples, but please don't be too impatient
because both pages can take upwards of 10 seconds to load.

http://128.32.224.162/Devt/servlet/autest

http://librarian.www7.kc.aoindustries.com/servlet/autest

In these two examples, the servlet has gone to the database
to load the author names to a Vector, and then the author
names are written to the browser by iterating through the
vector three times (I am not going to the database three
times). A single box using the MULTIPLE attribute will not
work in this case because the sequence of the selections
is significant. Also, if these option boxes are part of an
edit screen, the list has one of the names pre-selected,
so technically, the three lists could all be slightly different
from each other.

Here is the servlet code that produced the autest html
above: http://128.32.224.162/misc/optionBox/aucode.html .

I have read the discussion at
http://www.cs.tut.fi/~jkorpela/forms/countries.html
and yet cannot believe that what I'm trying to do is not
being done successfully by others.

Am I misguided in thinking drop down boxes are an
attractive means of making these selections available
to the user? Or am I just doing it wrong?

Last week I posted to comp.infosystems.www.authoring.html
but there's been no discussion there. If anyone over here
has ideas I'd love to hear them.

leigh

Ps. appreciated the recent middle-tier discussion.
I keep my business logic in java in the middle and
have been able to move my applications pretty easily
back and forth between SQL Server and PostgreSQL
(platform at work vs. platform at home). My applications
are comparatively small, however.

Christophe Vanfleteren · Guest

Graeme Hill wrote:

Graeme Hill · Guest

I would first of all run the servlet WITHOUT drawing the drop down boxes,
but still doing your database retreival.

If that is fast, then you should think about using a different selection
method, i.e. a search instead or a series of letters A-Z that displays
everything starting with A, B etc. Very long drop down boxes become
self-defeating as it takes users too long to find what they want.

If it slow, even without the drop down box I would :
(a) Look your indexing, use views etc - speed up the SQL
(b) Perhaps vectors are slow ? All of my recent work in this kind of thing
uses an array of strings (or objects) instead of a vector as you can run
through that extremely fast.

Best thing to do is find out what is fast, and what is slow, and go on
from there.

On Thu, 22 Jan 2004, Leigh wrote:

Leigh · Guest

Hey, it's great to get some feedback!

As for whether bringing the data to the
browser is faster when the option boxes are
not present, yes, pages that have as much
data loading, but not to option boxes, are
really fast. I'm pretty sure the option boxes
are the culprit here.

I've considered a few different schemes to
get the data from the user if I can't speed
up the option boxes. I could just use one
pickbox with a MULTIPLE attribute, and then ask
the user to sequence the authors later. This has
the added advantage of not requiring an arbitrary
number of permitted authors to be designated.

Also I've considered JavaScript (though am
unfamiliar it)-- I could just grab the resultset
and then use JavaScript to set it up for the browser.
It's something I should explore.

Thanks for the comments!
Still happy to hear any others!

leigh

Luke Webber · Guest

"Leigh" <leigh (AT) berkeley (DOT) edu> wrote

Manfred W. · Guest

The size of the whole page is about 177kb which is rather large for a HTML
page
and would load very slowly over dialup link. (Don't know what the server
connection is)

For me it seems to be on the server side, because if a load the whole file
from harddisk it is
shown in the browser nearly instantenously (IE6 and Firebird 0.7)

I daubt that any copying of data via JavaScript would be any faster.

Manfred

Leigh wrote:

Graeme Hill · Guest

Fair comment - I've not really used vectors much so it was a bit of a
shot in the dark.

As others have said, if the data retrieval and vector creation on its own
is fast, then the original poster should look at how he is displaying the
data. Any list that long or HTML source that big should be looked at again.

On Thu, 22 Jan 2004, Christophe Vanfleteren wrote:

Luke Webber · Guest

"Graeme Hill" <graeme (AT) hoofieuk (DOT) uklinux.net> wrote

Luke Webber · Guest

"Luke Webber" <luke (AT) webber (DOT) com.au> wrote

Leigh · Guest

Luke Webber wrote:

Luke Webber · Guest

"Leigh" <leigh (AT) library (DOT) berkeley> wrote

Leigh · Guest

You won't believe it, but it turned out to be
the Vectors I'm using!!!!!!

Check this out, it only takes a couple seconds to load,
and it's *five* boxes with all the original html.

http://128.32.224.162/Devt/servlet/autest5

Something Luke said about messing around with the
ResultSet got me thinking, and after some experiments,
I've discovered is that it's actually much, much faster
to work with the result set directly rather than read
results into a Vector and then do manipulation. And
that it's faster to go to the database five separate
times to get the SAME list, than it is to go once,
stick the results in a Vector, and then use the
Vector for iteration through the list.

Totally counter-intuitive to me. But thank god
I made some progress, and I have this group to
thank for that! My users thank you too! Everyone,
I appreciated everyone's comments.

leigh

Graeme Hill wrote:

Chris Smith · Guest

Leigh wrote:

Christophe Vanfleteren · Guest

Chris Smith wrote:

Leigh · Guest

Well, it's good to hear this. Maybe I am doing
something wrong in my use of Vectors. But they
just don't seem that complicated! I read each row
of the result set into an object, then stick the
object in a vector. I use a for loop to iterate
through the vector, casting each object as appropriate.

I'll post some code in the next couple days. Cuz if
I'm doing something wrong with the Vectors I'd just
as soon figure it out now rather than later.

thanks for the feedback!

leigh

Christophe Vanfleteren wrote: