Using XML and Frameworks to Develop

Information Systems

Toacy C. de Oliveira, Carlos J. P. de Lucena

Departamento de Informatica, Pontificia Universidade Catolica do Rio

de Janeiro

Rua Marques de Sao Vicente 225, Rio de Janeiro, RJ, 22453 900, Brazil

 

Key words: reuse, framework, domain analysis, XML, object

oriented.

 

Abstract: To accomplish the software development time and cost

constraints this development should take place in an environment

that helps the designer to deal with the large amount of concepts

obtained during the domain analysis phase and the semantic gap

between those concepts and the object oriented design model due to

their different levels of abstraction. This paper describes the main

features of an environment designed to support the development of

IS software based on framework reuse and XML specifications.

 

The cost and time to market constraints imposed on modern

software development oblige application designers to leave the made

from scratch approach and adopt a reuse enabled support to software

development. As a consequence during the system development

proven solutions such as Components [6] and Frameworks [7] must

 

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be composed with an application initial specification to obtain

the final design/code. It is also important that the act of achieving

this application initial specification be handled by a process that

captures domain knowledge and guides the application designer to

map/trace its translation to any design representation, such as Object

Oriented Design, from where the final specification can be extracted.

In this paper we report the ongoing development of an environ

ment that uses a Domain and Reuse Driven approach to the software

and development problem. This work is an extension of the approach

presented in [19] with the introduction of the XML/XMI standards

[10] to represent the designs involved. Another change to the approach

is the use of a framework design language to be able to deal with

generic framework specifications.

It is also important to mention that such an approach should be

based upon some characteristics:

n Compatibility — It must use market standards to provide

compatibility/integration with other systems.

n Code Legibility — During development the compilation/

debugging is usually done with a market IDE such as Borland

JBuilder and IBM VisualAge, so the user must understand the final

code.

n Focused on OO — The user must only know OOP techniques.

n UML — Due to OMG standards.

n Upgradable — Reuse actions such as inheritance, composition,

patterns, frameworks and aspects can evolve.

With these characteristics in mind our approach adopts market

standards like UML and XMI that are used as the basis of the repre

sentation of the diagrams involved. The approach begins by making

a thorough analysis to determine the common and different aspects

of the domain with the FODA Method [4] and Use Cases [13] to

reduce the so called “Semantic Gap”. After that the application

designer creates a class diagram based on the previous models that

will be used as the application ICEIS 2001 — Information Systems

Analysis and Specification.

In the reuse phase we have a modification of the traditional

software development approach where reuse should be handled. From

this phase a XMI representation of the domain specification is

 

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obtained to facilitate the composition manipulation of this

specification with the reuse specification (also expressed in XMI)

that is stored in a reuse repository.

After the choice of the reuse specification, which is done

empirically, the environment user will be guided to execute reuse

actions, stated as class redefinition clauses, pattern usage or

composition that have been defined by the reusable artifact designer.

Section 2 describes the approach overview and its adaptations to the

current processes. In Section 3 we describe how domain information

is collected. In Section 4 the reuse approach is depicted. Section 5

reports on a Rental System development used as a case study. In the

last section we present our conclusions.

 

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реферат .

 

Plain Talk About Computers

Al Fasoldt

The Syracuse Newspapers

 

It’s time for some plain talk about computers, this week and next.

If you find computers baffling, stick with me.

We’ll start by getting the jargon out of the way.

“PC” means personal computer, but it actually stands for the kind

of personal computer IBM invented. So that’s why you hear people

talk about “IBM compatible” computers — PCs made by other

companies that are like the ones made by IBM. More than 2,000

companies make PCs worldwide, and IBM is just one of a few dozen

really big PC manufacturers these days.

The only other kind of computer widely used in homes is the

Macintosh. It’s not like IBM’s PC. Despite what anyone tells you, it

doesn’t matter whether you use a PC or a Mac. But you need to know

that they work differently. If you have a Mac, you need Mac software;

if you have a PC, you need PC software.

“Software” is jargon for instructions that tell computers what to

do. Software is “soft” (unlike hardware) because you can’t touch it.

It’s like a set of directions — turn left, go two miles, turn right at

the light — written in a language a computer can understand. Usually,

 

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these “directions” are stored on a magnetic disk, either a small one

that can fit in your pocket or a larger one you can’t see that’s inside

the computer.

The small one has a hard plastic cover, but the disk itself is

bendable, so it’s called a “floppy” disk. The bigger one isn’t bendable,

and it’s called a “hard” disk. Last week I explained some of the jargon

that gets in the way when you’re trying to understand computers.

This week I’ll unravel the mystery of using a computer for the most

common task — writing. I’ll concentrate on how PCs work, since

most of us use PCs.

Everyone who uses a modern computer has a word processor.

Even if you didn’t buy a word processing program separately, you

still have the one your computer came with. You might know your

word processor as Write or Works or something else — maybe

WordPerfect or Microsoft Word.

The idea of a word processor seems simple. You type something,

and, when you’re through, you save what you wrote. You might also

print what you wrote.

But those steps aren’t simple at all unless you’ve done them

hundreds of times. Here are the basics:

Sometimes, before you can even start typing, you have to tell

the word processor you want to write something. (This seems odd to

me. What does the word processor think you want to do, make a

ham sandwich? But that’s how computers are — dumb as a lamp post.)

So you click your mouse on the word “File” at the top of the screen

and then on the word “New”. Your word processor should then show

you a fresh area where you can type. (Cranky work processors might

ask you what kind of document — what kind of writing thing — you

want to create. If so, click on whatever choice seems right. You’ll

have time to worry about those different types some other time.)

By now, you’ve got an area on the screen that has stuff at the top

and maybe at the sides and even at the bottom. Ignore all that junk.

It doesn’t do anything basic. Just type.

If you make a mistake, you can hit the Backspace key and get rid

of it, or you can work like the pros and double click on the word

that’s wrong. Doing that makes the word stand out. (It’s “selected”,

in nerd talk.) Whatever you type automatically takes the place of

the highlighted word.

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When you’ve finished writing, you have to tell the computer to

save what you wrote. Someone might tell you that word processors

automatically save what you write, but don’t believe what you hear.

(They might, and they might not, and they especially might not when

you really need to find that letter you wrote to the IRS.)

So you need to click your mouse on the word “File” again and

then click on the word “Save”. Then the fun starts. You’ll see a small

window with a lot of gibberish nearby. Ignore everything that doesn’t

make sense. Just type something that will remind you of what you

just wrote. (If you have a new PC or one that was new within the

last year, you can type something really long and strange. If you have

an old PC, you’ll have to type something short. But the main thing is

to type something that will jog your memory six months from now.)

A quick tech note: Whatever you wrote is on your screen, right?

But once you save it using the method I just told you about, it’s also

on your computer somewhere. (Don’t worry about where it is — we’ll

get to that next week.) So that means you can stop what you’re doing

and get rid of the word processor without losing what you wrote.

You get rid of the word processor by clicking on that old familiar

word, “File”, and then clicking on “Exit”. Hotshot users will tell you

there are fancier ways to get the word processor to go away, but don’t

listen to them. They’ll just confuse things.

Suppose you want to get the thing you wrote back up on your

screen? That can be a chore. We’ll see why next week.

These instructions won’t do any good if they’re just lying around

loose. So they’re strung together into programs. Just like TV

programs, software programs have a point where they stop and a point

where they end, with anything imaginable in between.

Programs need to be organized, too. They’re put in the computer’s

version of a filing cabinet. They’re kept in computer files and

computer folders.

You’ve probably seen something on your computer screen that

looks like a real folder. If you click your mouse button twice — called

double clicking — when the pointer is on top of a computer folder,

the folder opens up so you can see what’s inside it. (You might even

see more folders inside the first folder. There’s no limit.)

This idea of using a computer mouse to “open” something runs

pretty deep in the computer world. Even programs can be opened —

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in fact, that’s the word all the software companies use. When you

“open” a program, you get it going. You run it, in other words.

Another thing you open on a computer is a window. These days,

every program uses a window in one way or another. Sometimes

the window is the full size of your screen and sometimes it’s very small.

A window is a box. “Window” is a better term than “box” because

real windows give you a view of things, and computer windows do,

too. You can view a letter to Aunt Nellie or a page on the World Wide

Web or just about anything else.

A window usually has a bar along the top that works a little like

a billboard (because it advertises the program) and a lot like a grab

handle (because it lets you move the window). Move the window by

putting the mouse pointer on top of that bar and holding the mouse

button down while you move the mouse. The window travels right

along with your pointer.

The jargon for the part of the window that works like a grab

handle is “title bar” or “menu bar”.

This isn’t so hard, is it? Next week we’ll dig a little deeper.

I promise it will be painless. Modern computers give you two ways

to deal with documents. You can do something with the document —

you can click on it, for example — or you can find the program that

created the document and figure out how to deal with it.

Guess which way is easier?

Yet most computer users pick the harder way. That’s because most

of us know that computers can’t do anything without software, and

that means they need programs. And that must mean we need

programs, too. It means we have to struggle around the menus on

our computers to find the right programs in order to get something

done.

Wrong. This week, in the final installment in my miniseries on

the basics of using computers, I’ll tell you why that’s wrong. I’ll also

explain how to take advantage of the first technique. I promise you’ll

save both time and effort.

Here’s the idea: Documents — letters you write in your word

processor, financial statements you fiddle with in your personal

finance program, images you capture off a Web page — are the real

things in computing. Programs are just so much twaddle.

 

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What this means in simple terms is that the things you work

with, the stuff you want to see in your folders and on your desktop,

are documents. You want to see that e mail letter you got from your

daughter, as a clickable icon. You want to see an icon for last month’s

budget statement. You want to be able to click on the icon of a picture

and have it open on your screen.

Right? Isn’t that the way you want to work with your computer?

Then why do most of us do it the hard way? Why do we look

through a jumble of icons for the right program and then perform

the comedy routine of running it, going to a menu, choosing Open,

searching through the list that comes up, backing out of that list to

look somewhere else, and finally locating what we want?

Because we are creatures of habit. Because that’s how most of

us learned how to use a PC in the first few weeks of that new

adventure.

Here’s how to shed that habit. There are three simple steps, if

you’re using Windows 95 or a Macintosh.

n Try to save documents in only a few locations. Microsoft, maker

of Windows, uses a folder named My Documents for all documents

created by any of its Office 95 and Office 97 programs. It’s a good

idea, because documents are easy to find when they’re in one place.

Carry that one step further by saving your other documents in the

same kind of central folder whenever possible.

n Create a shortcut (or an alias, if you use a Mac) to your central

documents folder on your desktop. This puts your documents a click

or two away.

n Open that folder and double click on the document you want

to open.

Simple, right? You save a lot of steps and a great deal of time

because you let the computer do all the associating of programs and

documents. By focusing on the documents, you’re paying attention

to the important (and, sometimes, irreplaceable) items on your disk

drive. And you’re letting the computer handle the rest.

A few tips to guide newcomers before we leave this subject:

n File associations aren’t always done automatically. You can

create them yourself.

 

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You can create your own file associations in both Windows 3.x

(the old version) and Windows 95. (And, of course, in the heavy

duty version, Windows NT.) This idea — that you can change the way

the operating system responds when you click on an icon — is a very

powerful feature of a modern PC. I’ll describe some ways to do this

shortly.

n

File associations sometimes conflict with each other.

File associations in Windows PCs are based not on some esoteric

code within a file but on something almost absurdly simple —

the characters at the end of the name of a file. These characters are

called the filename extension. They always follow the last period in

a filename. (In Windows 3.x, there can be only one period in a filename,

but in Windows 95 and Windows NT there can be many.) MyFile.txt is

an example, as are MYFILE.TXT and This is my note to Mom on Mother’s

Day, 1997.doc and even What.Kind.Of.Fool.Am.I.README.TXT

(a name that works fine in modern versions of Windows!).

Because the operating system relies on filename extensions to

know which program should open a file, and because some extensions

(such as TXT and DOC) are quite common, you’ll find an occasional

program that insists on opening a file that “belongs” to another

program. Or you’ll want to fix a conflict when a new program you’ve

installed changes the associations you’ve been using. A full explana

tion of how to deal with this awaits another article, but we’ll take

a short tour of how to handle this problem below.

First, how do you create your own file associations?

Here’s how to do it in Windows 3.x (Windows 3.1 and 3.11).

(There are two ways, but I’ll describe the easiest method.) Run File

Manager. Click once on a file within one of File Manager’s windows

that has the filename extension you want to associate with a program.

(In other words, if you want all READ.ME files to be opened by

a certain program — all files with a ME extension, in other words —

click once on any file that has ME as its extension.) Then click on the

File menu, then on Associate.... Choose one of the programs listed in

the box that opens, or use Browse... to choose a program from any

location on your system. That’s all there is to it.

Here’s how to do it in Windows 95 and NT. (There are many

ways, but, again, I’ll keep it simple.) Double click on the icon for any

 

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file that does not have a file association. Windows will open a dialog

(a window) that asks you to choose a program that can open the file.

Click on the checkbox at the bottom of that dialog to tell Windows it

should always use the program you choose. Find the program in the

list, or browse to a program that’s not listed, then select it. That’s it.

What if file associations conflict with each other?

A common example for old timers is the DOC filename extension.

Old MS DOS texts (and some modern ones) use DOC as the extension

for documents that explain how a program works. These old style DOC

texts are nearly always ASCII texts — plain texts, without any word

processor codes. With the ascendancy of Microsoft Word, DOC has

become the standard filename extension for Word documents. If you

double click on a DOC file, and if you have Microsoft Word installed

on your PC, Word will open the file.

This is fine if the file is a Word document, but a waste of time if

the file is a plain ASCII text. (Word takes a long time opening files

anyway. And, although it will, all on its own, figure out that a file

with a DOC extension is not a Word file at all but an ASCII text, it

has the gall to stop and ask you if the file is really a standard text!

This behavior can be changed, however; look in the configuration

options.)

So plain texts are better opened in Notepad (or in a replacement

for Notepad, which I’ll discuss shortly). In Windows 3.x, you’re stuck

with a couple of choices. You can run your text editor, then manually

open the file from the File menu, or you can drag the icon for the file

over to the text editor window and drop it there. In Windows 95 and

NT, you can add an option to the context menu of the type of file

you’re dealing with. I’ll deal with that another time in some detail.

But if you want to try your hand at it now, just open an Explorer

window (a folder window, in other words), choose View, then Options,

then File Types, and navigate to the type of file you want to add an

association to. Follow the prompts when you find it to create a new

action (use Open with when you add an action, for example).

A personal note: Ordinarily, I’d say at this point that you might

want to associate Notepad with such files as READ.ME, but I don’t

recommend Notepad to anyone. There are dozens of good replace

ments for Notepad for both old and new versions of Windows, so

 

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take my advice and pick up a good Windows text editor and dump

Notepad.

 

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Steganography Revealed

Kristy Westphal

SecurityFocus

Over the past couple of years, steganography has been the source

of a lot of discussion, particularly as it was suspected that terrorists

connected with the September 11 attacks might have used it for covert

communications. While no such connection has been proven,

the concern points out the effectiveness of steganography as a means

of obscuring data. Indeed, along with encryption, steganography is

one of the fundamental ways by which data can be kept confidential.

This article will offer a brief introductory discussion of stegano

graphy: what it is, how it can be used, and the true implications it

can have on information security.

 

What Is Steganography?

While we are discussing it in terms of computer security,

steganography is really nothing new, as it has been around since

the times of ancient Rome. For example, in ancient Rome and Greece,

text was traditionally written on wax that was poured on top of stone

tablets. If the sender of the information wanted to obscure

the message — for purposes of military intelligence, for instance —

they would use steganography: the wax would be scraped off and the

message would be inscribed or written directly on the tablet, wax

would then be poured on top of the message, thereby obscuring not

just its meaning but its very existence.

According to Dictionary.com, steganography (also known as

“steg” or “stego”) is “the art of writing in cipher, or in characters,

which are not intelligible except to persons who have the key;

cryptography”. In computer terms, steganography has evolved into

the practice of hiding a message within a larger one in such a way

that others cannot discern the presence or contents of the hidden

message[3]. In contemporary terms, steganography has evolved into

 

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a digital strategy of hiding a file in some form of multimedia, such as

an image, an audio file (like a .wav or mp3) or even a video file.