A cgi Strategy

David W. Brooksdbrooks1@unl.edu

http://dwb.unl.edu

• Pre-history

• Overview of tasks

• HyperCard Model

• RunRev I

• RunRev II

• Current

Tools

• Videodisc Drivers

• AP Chemistry

• Graduate Advisor

• NSF Proposals

• Courses (Web only)

13 Videodisc Sides

Redox

AP Chemistry

Graduate Advisor

NSF Proposals

All forms including budgets with computation and built-in rules.

Courses

Courses had full administration [“add” students; take quiz items; complete and submit essays; see progress].

Everything on-line except for grades.

Bread & butter.

HyperCard Model

• Works exceptionally well

• Overnight restart

• Backup

• Data storage work arounds

For example, 30K limit on return size but no (important) limit on file/script size.

So, when large amount of data to return (i.e., > 30 K), write html to a file and then upload the written file.

Use multiple storage fields.

Store scripts in buttons or other objects.

Two servers• dwb.unl.edu (OS 9)

• chemmovies.unl.edu (OS X)

~ 15 gbytes/month each

Bottom of the line iMacs

The Servers

Will be replaced with xserves shortly after my return

Days are Numbered

Choices:

• retire

• find a new delivery option

LifeChanging

Event

Shafer book (earlier)RunRev Workshop

[met Rinaldi and felt it to be an almost religious experience -- like meeting a saint]

Jacque Landman Gay session on cgi

No practice; thought would be just like HC. Went home really hyped.

(2% never get the word.)

RunRev Approach IBy mid-March I had figured out that I couldn’t write to a field, and that appleEvents were a problem with Apache.

Discovered acgi Dispatcher

Had stacks going just as in HC and was well on my way to implementing a 1-for-1 conversion of RunRev replacing HC.

Had done LOTS of testing.

In September, disaster struck.

I had software not mentioned running my theory course. Students submitted essays. I still have better evaluation tools than, say, BlackBoard. Things went haywire.

Bottom line: acgi Dispatcher has a 211 byte limit (2048). I really need 215.

Ended up getting Randy Sargent (who programs robots for Martian landings among other things) to write a script that would allow enough input. Worked, but was kind of nasty.

I showed up at RevCon West 2005 with one course stack working -- doing everything!

I was anticipating going back to Lincoln to convert all of our courseware and other materials to what amounts to a HC upgrade.

Got some advice -- but I don’t remember from whom about making a change to use sockets.

But then I heard a talk from Jerry Daniels [an unreconstructed hippie from Austin] about using xml-like files.

His comments made a hugeamount of sense. I had seenhim show very impressivetools in 1/04, too. His “Inspect”stack tool is fantastic.

I decided to reconsider my entire strategy.

I had considered mySQL. I had sat in on two courses in the Spring of 2005 (Steckelberg, Reichenbach).

The notion of creating xml-like files had a great deal of appeal. Jerry convinced me it would be fast enough.

In June 2005, I began looking at a new approach

RunRev Approach II

Use a RunRev cgi script

Store data in xml-like files

That’s where I am today.

The xml-tools in the Darwin engine used in Mac OS didn’t seem to work for me.

I bought the 3rd party tools from Sons of Thunder (Ken Ray) but it didn’t seem to do what I wanted.

I reverted to kind.

Fake xml

Line 1 lists all elements

Line 2 defines file

Line 3 and last line identify encompassing element

Other lines are elements, data.

put ExtractXMLRecord(quizItemRecordPath) into

quizItemRecord

function extractXMLRecord recordPath put URL("file:"&recordPath) into xxx replace numtochar(13) with linefeed in xxx put line 1 of xxx into recordKeys put recordKeys into recordName["theKeys"] delete line 1 to 4 of xxx repeat with x = 1 to the number of words of recordKeys put word x of recordKeys into currentKey put "</"&currentKey&">" into currentCloseTag get offset(currentCloseTag,xxx) put quote&(word x of recordKeys)&quote into label put char 1 to (it-1) of xxx into recordName[value(label)] delete char 1 to it of xxx delete line 1 to 2 of xxx end repeat return recordNameend extractXMLRecord

The net result of this is that all of the data is taken from elements and placed into an array in which it can be manipulated.

Any changes can be recorded.

on rebuildXMLRecord recordName, mainTag, recordPath put recordName["theKeys"] into keysList put keysList&LF into yyy put "<?xml version='1.0' ?>"&LF after yyy put "<"&mainTag&">"&LF after yyy repeat with y = 1 to the number of words of keysList put word y of keysList into currentKey put quote&currentKey&quote into label put "<"&currentKey&">"&LF&recordName[value(label)] after yyy repeat while ((last char of yyy = LF) or (last Char of yyy = return)) delete last char of yyy end repeat put LF&"</"&currentKey&">"&LF after yyy end repeat put "</"&mainTag&">" after yyy put yyy into URL("file:"&recordPath)end rebuildXMLRecord

Systematic Element NamingFirst Character

“L”; data normally would be edited from a single line text-entry field in a WebForm

“F”; data normally would be edited from a textarea entry field in a WebForm

“A”; some kind of data list (with structure)“C”; data calculated or extracted and maybe should

not be editable.

By having systematic naming, the files can be Web-edited using generic tools.

Hidden Fields

Key info is place in hidden fields.

Courses

CalculatedTopic List

Blue indicatesquestion

Content

Buttons atbottom accessassessment.

Green linksmean contenton UNLServer.

Item

Assessment

Assessment

Time Stamp

Used to prevent resubmitting answer. Since the feedback is immediate, prevents using back button, changing answer, and submitting for regrade.These are recorded in the question file.

Performance

Times vary from 5 milliseconds (tool script of some sort) to ~1,000 mseconds. Typical transactions take less 100 mseconds (on an iMac like the one running dwb.unl.edu).

So far, performance has not been a problem. Also, there are several ways to think about improving performance.

Favorites

Problems

Having trouble with automatic e-mailing. Hopefully some variation or extension of a solution provided by André Garzia will start working.

Issues

When to use a Web cgi and when to use a Web appliance.Used to have 30-40 stacks for teaching HC. Devin Asay has developed similar stacks for RunRev. We have made these into a Web appliance; should be available soon.We may start a writing project for grades 1-3 kids wih writing difficulties based upon earlier HC ROBO-Writer.

Thanks

Thanks for giving me the opportunity to describe our work. I’ll try to entertain questions, and will be very pleased to receive any suggestions you my have.

Go Rev!