August 21, 2006

"LOGICAL VS. PHYSICAL DESIGN: DO YOU KNOW THE DIFFERENCE?"

The physical aspects of our information resources are well understood by developers; e.g., computer hardware/software, DBMS files, manual files, screens, reports, forms, etc. The logical side of our resources is a bit more nebulous, yet just as important, if not more so, than their physical counterparts. Think about it. In its simplest form, logical information resources include data and process components. The physical components describe "how" it will be implemented. For example, companies have been implementing payroll systems for many years prior to the advent of the computer. We have seen payroll implemented manually, then with time clocks and punch cards, followed by automation on mainframes, minis and PC's. We have also seen such innovations as "direct deposit" to expedite paying employees, and electronic government reporting. All of these devices are simply a physical variation of a theme. Its a lot like music; the composition represents the logical and the orchestration represents the physical. For example, Paul McCartney of the Beatles wrote one "Yesterday," yet hundreds of renditions of it have been recorded by different artists over the years.

The physical implementation is ultimately based on available technology and, as such, changes dynamically. In contrast, the logical side represents the inherent nature of a business and only changes if the business changes, which is considerably less volatile than the physical.

It is important to understand that logical design is a precursor to physical design. In other words, the physical implementation must serve the business, not the other way around. Too often this is a false assumption and developers spend an inordinate amount of time and money devising a technical solution without fully understanding the logical design. This is commonly referred to as "the cart before the horse" phenomenon. The logical design of information resources always precedes physical design. Failure to do so is an exercise in futility.

RE-ENGINEER?

I now hear pundits in the industry saying companies have to re-engineer their systems in order to implement SOA (Service Oriented Architecture). Are we really re-engineering or are we simply introducing a new physical implementation? Frankly, it is the latter. In an earlier bulletin, I described this logical/physical phenomenon as implemented by a large Fortune 500 conglomerate; see:

No. 8 - "Is Software Hard?" - Jan 24, 2005

Basically, the company devised a standard Payroll System to be implemented by all of their divisions on a worldwide basis. They first produced a complete logical design of the system, followed by a single physical implementation (the recommended standard to be used). Recognizing some of their divisions might need to use other computer equipment, they provided the logical design for these divisions to implement. This resulted in multiple physical implementations of the same logical payroll system, all working harmoniously together. This included implementations using IBM MVS, VM, Honeywell GCOS, UNIVAC Exec, HP MPE, and DEC VAX/VMS. What this illustrates is that a logical design can be implemented many different ways, not just one. The conglomerate didn't have multiple systems; only one, with multiple physical implementations.

The reason developers are more imbued in physical design as opposed to logical design is rather obvious; the physical components are much more tangible than the logical components. Because people can "touch and feel" something, they are more likely to relate to it. As a small example, there are those people who can read a set of blueprints and comprehend what a house or building will look like. But in contrast, there are those who need to walk through a physical model in order to assimilate what the structure will look like.

It is because of our natural inclination to assimilate the physical design, and not the logical, that people find it easier to describe screen or report layouts as opposed to business requirements.

TYPES OF INFORMATION RESOURCES

As I have described many times in the past, there are three types of information resources: Business components (the consumers of the information), Systems components (representing processing), and Data components (the facts and events of the business). There are logical and physical dimensions to all three:

BUSINESS COMPONENTS

Logical: Functions - a prescribed scope of duties and responsibilities.

Physical: Jobs/Positions (one job may implement multiple functions, and one function may be implemented by multiple jobs), and Human/Machine Resources.

SYSTEM COMPONENTS

Logical: Systems, and Sub-Systems (representing a business process).

Physical: Procedures (both manual and automated), Steps (tasks), Programs, Modules/Subroutines

DATA COMPONENTS

Logical: Data Bases (logical), Objects (logical files), Views (logical records), Data Elements, Inputs and Outputs.

Physical: Data Bases (physical), Files (manual and computer), Records, Data Elements, Inputs and Outputs.

You'll notice that Data Elements, Inputs, and Outputs are listed as both Logical and Physical. Logically, Data Elements have a single definition (representing a single fact or event) but can be implemented physically many different ways. For example, "Ship Date" has one logical definition but can be expressed many different ways;

20060403
04032006
040306
03 Apr 2006
April 3, 2006
04/03/2006

Inputs represent how data is collected and Outputs represent how information is conveyed. As in the Payroll System example mentioned earlier, Inputs and Outputs were defined logically first, then implemented physically to suit a particular physical environment. Inputs and Outputs are designed logically for Sub-Systems, and physically for Procedures, Steps, Programs, etc.

As the various logical components are defined, they are then linked to the physical components implementing them, thereby demonstrating how the physical solution satisfies the logical problem. To do so, a Repository is needed to map such relationships.

THE LOGICAL BUSINESS

This differentiation between logical and physical is vital for successful design. To illustrate:

• By having a logical model of the business (functions), we can determine a suitable physical implementation of jobs, and human/machine resources.

• By having a logical model of a system (sub-systems with logical inputs, outputs, and files) we can determine a suitable physical implementation.

• By having a logical model of a data base (objects), we can determine a suitable physical design of the data base.

It is the failure to prepare such logical designs that inevitably leads to problems in physical design later on, particularly when it is necessary to prove that a physical solution solves a logical design (aka, "Design Correctness"). Before we embark on a costly re-engineering project (whether it be to implement SOA or whatever the next technological innovation will be), perhaps it would be wise to first take stock of our logical components so we know what we are ultimately implementing.

But let's take it a step further; if we can logically model a type of business (such as a bank, insurance company, etc.), then it shouldn't be too difficult to develop standard templates for implementing businesses physically. This was the point of a past article:

No. 23 - "Using Logical Models as Templates" - May 09, 2005

This suggests corporate success is greatly influenced by who has the best physical implementation of the logical model.

CONCLUSION

The logical model is stable; it will only change if the business changes (due to mergers, acquisitions, diversification, new products/services, etc.). The physical model is much more dynamic, and is ultimately driven by changes in technology. The physical model is certainly not irrelevant, but I believe we have become too bound to it. A logical model represents independence of our physical environment, thus permitting mobility and portability to new physical environments. If done properly, new physical models can be implemented less painfully than they are today. In fact, a good logical model expedites the implementation of the physical model.

Logical design has been an inherent part of the "PRIDE" Methodologies for IRM for a long time. In "PRIDE"-EEM (Enterprise Engineering Methodology), Phase 2 is used to define the logical model of the business (functions). In "PRIDE"-ISEM (Information Systems Engineering Methodology), Phase 2 is used to define the logical model of a system (sub-systems). In "PRIDE"-DBEM (Data Base Engineering Methodology), Phase 2 is used to define the logical data base model for a system; Phase 3 is used to define the logical data base model for the enterprise. Of course, phases for physical design are also included.

Some see logical design as a pipe dream. I see it as a practical reality. The problem though is thinking in terms of logical models. Most developers today think only in terms of the physical aspects of our information resources. Devising a logical model requires someone more in tune with the business as opposed to technology. This used to be the forte of the Systems Analyst which, regrettably, is an obsolete job description. Instead, it defaults to Enterprise Architects who should be more adept at seeing the bigger picture.

OUR BRYCE'S LAW OF THE WEEK therefore is...
"Whereas logical information resources will remain relatively static, the physical resources will change dynamically."

"BRYCE MANAGEMENT ANALYSIS" SERVICE INTRODUCED

We've just introduced a new free service for managers to perform a self-analysis of their style of management, including leadership and corporate culture. Check it out at:

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IN OUR "DOWN THE ROAD" SECTION

The British Academy of Management will be holding their 2006 Conference at The Waterfront Hall and Hilton Hotel, in Belfast, Northern Ireland on September 12th-14th. For information, contact Clare Saunders in their London office at +44 (0)20-7383-7770 or visit their web page at: http://bam.ac.uk/

The Society for Information Management will be holding their SIMposium 2006 on September 17-20 at the Fairmont Hotel in Dallas, Texas. For information, contact SIM headquarters in Chicago at 312/527-6734

Verify 2006, the International Software Test Conference, will be held October 10th-11th in Washington, DC at the Crown Plaza Hotel Crystal City. For information, call 703/725-3051.

The International Institute of Business Analysis will be holding their World Congress for Business Analysts (in conjunction with ProjectWorld 2006) on November 6th-9th at the Caribe Royale Hotel in Orlando, FL. For information, call 212/661-3500 x 3702 or visit their web site at: www.iirusa.com/baw

If you have got an upcoming IRM related event you want mentioned, please e-mail the date, time and location of the event to timb001@phmainstreet.com

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While there, look for our new MS PowerPoint presentation describing both the book and the training program.

MY "PET PEEVE OF THE WEEK" IS "YES MEN"

We've all seen instances where subordinates mindlessly agree with everything the boss has to say; we call these people "Yes Men." I'm not really sure why we have such people. Maybe its because the boss wants to surround himself with clods to bolster his self-esteem. Maybe its because people are afraid of disagreeing with the boss in fear of losing their job. Or maybe its as simple as people no longer know how to engage their brains and allows others to make decisions for them. I tend to think its the latter.

Let me ask you something, what is wrong with a little critical thinking? I get involved with a lot of discussion groups on the Internet, both professional and nonprofit groups and am not afraid to put in my two cents. I'm not always looking for everyone to agree with me; a lot don't. Instead, I thrive on the discourse and find such discussions as fruitful for bringing forth new ideas and finding solutions for problems. Some people are scared to participate in such groups and either remain quiet or simply maintain the party line. I call these types of people "cowards" or "sheep."

One of my favorite movies is "Twelve Angry Men," an old black-and-white courtroom story starring Henry Fonda, Lee J. Cobb, Jack Klugman, and others. The story centers on the dynamics of a jury who must decide the fate of a teenager in the murder of his father. At first, the jury consists of mostly "Yes Men" who simply want to prosecute the teenager and move on with their lives. Fonda wants to discuss the case in more detail before making a snap decision, and is castigated by the others for slowing them down. By discussing the evidence in more detail, the jurors, one by one, determine the teenager is innocent. In particular, there is an interesting scene where one of the jurors changes his vote from guilty to innocent more as a whim as opposed to any specific evidence. This infuriates another jurist who challenges the other to explain why he changed his vote. This is an excellent example of how "Yes Men" can get into trouble, simply because they refuse to engage their brain.

What we need in business today are fewer "Yes Men" and more people who can use their heads. But I guess that requires work.

Such is my Pet Peeve of the Week.

FRAPPER MAP

Friends, I don't know if you've seen it yet, but we've added a Frapper map to the "Management Visions" web site. Frapper is a free mapping service offered by the folks at Rising Concepts, LLC, and allows you to plot yourself on a worldwide map. This is a great way to keep track of our listeners and I encourage you to try it out through our web page or by clicking HERE.

AND FINALLY...

I received an e-mail from a Jeff Faber in Wyoming who wrote me regarding last week's essay entitled, "The I.T. Director's New Tools."
Jeff writes:

"I enjoyed your broadcast last week. I can relate to it in my shop alone. I'm sure others are experiencing this phenomenon as well."

Thanks Jeff for your note,

Yes, there is a huge temptation to solve all of our problems with technology, not management. Some say its thanks to Hollywood for shows such as "Star Trek" who promotes the concept of conquering everything through technology. But I think its more fundamental than this. Comedian George Carlin years ago talked about how we have developed a drug related society. Even as a child we are taught to take a pill for whatever is ailing us. Got a problem? Take a pill he claimed. Its the easy way out. The same is true in the systems world. Got a problem? Get more technology. This has led to a general philosophy in systems development where companies take superficial remedies which may pacify a problem for the moment but causes greater problems later on. I contend that you cannot keep applying Band-Aids when major surgery is required. The mindset in the industry now is that the only legitimate business problems worth addressing are those involving the latest technology. To me, this is a lazy form of thinking. And maybe that's the point Carlin was trying to make; that we don't always do what is right, but what is expedient instead. I believe technology has its place but I'm surprised how companies fail to raise their consciousness and try to think outside of the box. You can solve more problems through good old-fashioned management than you can through the latest technology.

Again, Thanks for your e-mail. Keep those cards and letters coming.

MBA is an international management consulting firm specializing in Information Resource Management. We offer training, consulting, and writing services in the areas of Enterprise Engineering, Systems Engineering, Data Base Engineering, Project Management, Methodologies and Repositories. For information, call us at 727/786-4567. For a complete listing of my essays, see the "PRIDE" Special Subject Bulletins section of our corporate web site.

Our corporate web page is at:

http://phmainstreet.com/mba/

Management Visions is a presentation of M. Bryce & Associates, a division of M&JB Investment Company of Palm Harbor, Florida, USA. The program is produced on a weekly basis and updated on Sundays. It is available in versions for RealPlayer, Microsoft Media Player, and MP3 suitable for Podcasting. See our web site for details. You'll find our broadcast listed in several Podcast and Internet Search engines, as well as Apples' iTunes.

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Copyright © 2006 by M&JB Investment Company of Palm Harbor, Florida, USA. All rights reserved. "PRIDE" is the registered trademark of M&JB Investment Company.

This is Tim Bryce reporting.

Since 1971: "Software for the finest computer - the Mind."

END