Architecture

The importance of Conceptual Integrity

Conceptual integrity is the quality of a system where all the concepts and their relationships with each other are applied in a consistent way throughout the system.

 

Fred Brooks in his classic The Mythical Man-Month talks about conceptual integrity - 

"I will contend that conceptual integrity is the most important consideration in system design. It is better to have a system omit certain anomalous features and improvements, but to reflect one set of design ideas, than to have one that contains many good but independent and uncoordinated ideas."

"Conceptual integrity in turn dictates that the design must proceed from one mind, or from a very small number of agreeing resonant minds." 

 

Conceptual Integrity does not emerge from democracy; see A Camel is a Horse designed by a committee. The result of a democratic approach is a compromise that does not meet the needs of any single person or the customer.

 

Conceptual integrity is extremely important in product designs. See an API that is very easy to use, even without documentation? See a website that achieves the same task in the same way across various web pages? See the employees in an organization articulate the product concepts in a consistent manner? These are all results of conceptual integrity that has been successfully achieved.

 

So, how does one achieve it. Fred brooks offers an elegant and obvious solution:

"... the most important action is the commissioning of some one mind to be the product's architect, who is responsible for the conceptual integrity of all aspects of the product perceivable by the user."

"For quite large products, one mind cannot do all of the architecture, even after all implementation concerns have been split off. So it is necessary for the system master architect to partition the system into subsystems. The subsystem boundaries must be at those places where interfaces between the subsystems are minimal and easiest to define rigorously. Then each piece will have its own architect, who must report to the system master architect with respect to the architecture."

 

Of course, managers need to recognize the importance of conceptual integrity, and organize to ensure its realization ...

  

Middleware as Underwear

I attended a talk recently about an application that consumers can use to make better shopping decisions across various ecommerce sites. The architect for the application began his presentation by talking about the infrastructure (or middleware) that was used to build the application, which included the 'cloud', 'NoSQL'. The presentation was attended by several engineers in the valley, and was well received, until a member of the audience asked - how was the choice of infrastructure influenced by the customer need for better and faster shopping decisions? As it happened, the benefit was really to the company in minimizing its operating costs, and the application could have better served the customer with a different style.

This reminded me of an article by Jack Wileden and Alan Kaplan titled Middleware as Underwear: Toward a More Mature Approach to Compositional Software Development. With a catchy title, it highlights the role of infrastructure in application development, that is much like the underwear should not dictate the type of clothes someone wears, the middleware in an application should not be the center of attention and dictate the application design.

The article further goes on and identifies other similarities between middleware and underwear

1. Excessive fascination with it suggests immaturity

2. In general, it should be kept hidden from public view. Not even seams should be apparent.

3. It should never dictate, limit or prevent changes in what is publicly visible.

4. In most circumstances, it should be as simple as possible.

5. It must be reliable. Failures can have embarrassing, and often painful, consequences.

Read the complete article for more details

 

A camel is a horse designed by committee

An individual makes the case for a product (horse). It is introduced to few people who realize its potential. The stakeholders engage and define a process and committee (one representative from each stakeholder), with no one in lead. The committee develops a camel (the individual has probably moved on).

Per Wikipedia "Design by committee is a term referring to a style of design and its resultant output when a group of entities comes together to produce something (often the design of technological systems or standards), particularly in the presence of poor leadership. The defining characteristics of "design by committee" are needless complexity, internal inconsistency, logical flaws, banality, and the lack of a unifying vision."

An approach that produces something closer to a horse

1. Let the product germinate and bloom with the individual
2. Let the shoot emerge and support the individual with a small set of people who collaborate
3. Incrementally let the product grow the realties of the world and support it with more people
4. Keep the individual at the core maintaining the vision
5. Keep the committee far away

 

 

Vitruvius on Architecture - The Education of the Architect

Marcus Vitruvius Pollio was a Roman architect and engineer who lived around 80 - 15 BC. He is best known for his Ten Books on Architecture, a treatise on Architecture, dedicated to his patron Caesar, as a guide for building projects.

The ten books provides a great perspective on various aspects of architecture. In Book 1, Vitruvius writes about the education of an architect, which is summarized below.

The Education of the Architect

1. An architect should be equipped with knowledge of many branches of study and varied kinds of learning. This knowledge comes from the combination of practice and theory,

2. The architect should be thorough in this knowledge, which comes from both scholarship as well as manual skill. One without the other does not make an effective architect.

3. One who calls himself an architect should be well-versed in both defining the architecture of something, but also be able to demonstrate its significance through scientific principles. For this, an architect not only needs to have the natural abilities, but also be amenable to instruction.

4. An architect needs to be able to describe the architecture (e.g. through drawings) and be well versed in the tools (e.g. geometry).

5. An architect needs to be a philosopher and not self-assuming. Philosophy makes him courteous, just, and honest without avariciousness. This is very important, for no work can be rightly done without honesty and incorruptibility. He should not be grasping nor have his mind preoccupied with the idea of receiving perquisites.

6. An architect needs a good understanding of the functional attributes of technologies used in building. Vitruvius refers to bronze vessels, which were placed in under the seats in theatre in accordance with the musical intervals to improve the fidelity of sound affects.

7. An architect should be aware of environmental constraints. Vitruvius talks about the need for architects to be aware of law regulations that can constrain the design of buildings.

8. People have no right to call themselves architects hastily, without having climbed from the bottom of the steps of the knowledge necessary, then educating themselves by the knowledge of many subjects, and reaching the heights of the architecture profession. In essence, it takes time and experience to become an architect.

9. It is difficult for someone to gain expertise in the breadth of areas needed for a good architect. Good architects are therefore rare. While an architect may not be the best in all these areas, they will be good in understanding and focusing on the principles that brings these areas together. They will depend on the experts in these areas when necessary. What is interesting to note is the realization of the need for architects to understand domains and work with domain experts closely.

More on Architecture by Vitruvius in upcoming posts.