Published: Thursday, July 08, 1999
Building an Internet Database Drilldown
Application,
Part 2
Read
Building an Internet Database Drilldown
Application,
Part 1
Read
Building an Internet Database Drilldown
Application,
Part 3
Webmaster's Note:
In this article, Roger creates a Session-level Connection object. This is not the best thing to do.
Placing large objects in Session level variables can be disadvantageous. Please refer to the following
articles for more information on Session level variables:
Making the database connection ... well
not quite yet.
Can I do this the easy
way?
I looked at several editor options when creating the
ASP pages for
the drilldown application. I've tried FrontPage (various versions) several
times. But I
keep putting it away. A few things about it drive me crazy. First of all, I
don't want my
editor to reformat my pages for me. I write code that I think is well laid
out and
understandable. Just about every time I get it looking just right, I hit the
save button
and FrontPage turns something like this:
| <form method="POST" align="center" action="signup3.asp">
< input type="hidden" name="fname" value="<%=fname%>">
<input
type="hidden" name="lname"
value="<%=lname%>">
<input
type="hidden" name="address"
value="<%=address%>">
<input
type="hidden" name="city"
value="<%=city%>">
<input type="hidden"
name="state" value="<%=state%>">
<input
type="hidden" name="zip"
value="<%=zip%>">
<input
type="hidden" name="phone"
value="<%=phone%>"> |
into this jumbled mess:
| <form method="POST" align="center" action="signup3.asp"> <input type="hidden" name="fname" value="<%=fname%>"><input type="hidden"
name=" lname" value="<%=lname%>"><input type="hidden" name="address"
value=" <%=address%>"><input type="hidden" name="city" value="<%=city%>"><input
type=" hidden" name="state" value="<%=state%>"><input type="hidden" name="zip"
value=" <%=zip%>"><input type="hidden" name="phone" value="<%=phone%>"> |
I'm sure there is an option I can select that will
stop this, but I
usually slam the FrontPage editor shut before I ever get a chance to check
it out.
Then, when you are debugging with FrontPage, and your
browser (such
as Netscape or IE) says you have an error on line 483 of your ASP file, how
do you find
that number in FrontPage? Start at line 1 and count down 482
times.
Visual InterDev is pretty good if you don't mind doing
things
Microsoft's way, which is of course to make the easy thing easy, and the
hard things
impossible. I don't think I am a purist, but when I write code, I want
my
code on the server, not the 47,000 lines of code InterDev adds to your HTML
to create a
simple online form.
I have even tried using the Microsoft Access wizard to
export to
ASP. Right. If you get that thing to create anything like a usable data
entry form that
isn't 20 times the size of a handwritten form, please let me know what magic
you used. And
do I really want my users to rely on an HTML layout form object? I thought
it was my job
to layout HTML.
So, the solution. Notepad. Works great. Lightweight.
Also, I have
started using ASP Express, a shareware product, and it does a really good
job as well. And
you get line numbers!
Global.asa...Session State...Application
Startup...WHAT?
First thing: the global.asa is an optional file. So
you can do
without it, but it does offer some advantages to the ASP developer. It is a
place to store
event scripts and declare objects that have session or
application
scope. The contents of the global.asa are not viewable by users and must be
stored in the
root directory of the application.
Here's what a global.asa with empty event scripts
would look like:
<script
language=vbscript
runat=server>
SUB Application_OnStart
'The Application_OnStart event is executed the first time that an
ASP page within
an application is requested.
END SUB
SUB Application_OnEnd
'This event is called when the application ends. This could be
cause by the
application being inactive for a period of time or the web site being
stopped.
END SUB
SUB Session_OnStart
'This event is executed for each user when they first request a
page within an
application.
END SUB
SUB Session_OnEnd
'This event is called when a user's session ends. This could be
cause by an
explicit end (ie: session.abandon) or the session timeout being
exceeded.
END SUB
</script> |
And here is how the global.asa might be used for an
application that
uses a DSN-less connection to an Access database.
| <SCRIPT
LANGUAGE="VBScript" RUNAT="Server"> |
|
|
| Sub
Application_OnStart() |
|
|
Application("DB_PATH")
= "D:\mydomain\database" |
|
Application("DB_CONNECTION_STRING")="DBQ="&
amp;Application("DB_PATH")
&
"\mydatabase.mdb;DefaultDir="&Application("DB_PATH")
&";
Driver={Microsoft Access Driver(*.mdb)}; DriverId=25;FIL=MS Access;
ImplicitCommitSync=Yes; MaxBufferSize=512; MaxScanRows=8;
PageTimeout=5;Threads=3;
UserCommitSync=Yes;" |
|
Application("DB_CONNECTION_LOGIN")
= "test" |
|
Application("DB_CONNECTION_PASSWORD")
= "1234" |
| End Sub
|
|
|
|
| Sub
Application_OnEnd() |
|
|
' Do not do
anything |
| End Sub |
|
|
|
| Sub
Session_onStart() |
|
|
' Connect to
the database
Set Session("DB_CONNECTION") =
Server.CreateObject("ADODB.Connection")
|
|
Session("DB_CONNECTION").Open
Application("DB_CONNECTION_STRING"),
Application("DB_CONNECTION_LOGIN"),
Application("DB_CONNECTION_PASSWORD") |
| End Sub |
|
|
|
| Sub Session_onEnd()
|
|
|
' A graceful
disconnect
Session("DB_CONNECTION").Close |
|
Set
Session("DB_CONNECTION") = Nothing |
| End Sub |
|
|
|
| </SCRIPT> |
|
As you can see, every new session
looks to the application
for information. You can say that the application object serves all
users,
the session object serves only a single user.
And so, since we have used the global.asa to create a
database connection
with each session, now each page of our ASP need only concentrate on
creating recordsets
and manipulating data. And we are guaranteed (or at least better our chances
of) a
graceful exit when the session ends.
BTW, give it all up if your user won't accept cookies or
can't because
of their browser type. It's just too hard! Session state is maintained by
cookie objects,
even though they may never be written to the client machine. If you have
users that don't
accept cookies, you will need to test for this on your startup page and
redirect them
another page that tells them how to accept them. Or you can scrap the whole
session idea,
and create a new connection on each ASP page. But since no login credentials
have been
saved (no cookies), they will have to login on each and every page. Doesn't
sound like
fun.
Next ... Data
please!
Read
Building an Internet Database Drilldown
Application,
Part 1
Read
Building an Internet Database Drilldown
Application,
Part 3
Directed
Minds is a web
development company specializing in hosting and developing ASP, database and
ecommerce
solutions for large and small organizations.
Roger
Drye is the owner
of Directed Minds. He has been developing Internet solutions for small
and large
companies and government entities for many years.
