Skip to main content

Different aspects of software design

Yesterday while talking about goals of software design with some learning participants, we had an interesting discussion about the various aspects of software design. It is analogous to designing a housing complex. There is the macro level design of the buildings, gardens, club house, and jogging track. Then within every building we design the floor plan and the elevation. Each apartment has it's interiors designed separately. Beyond these designs, we also design the electrical systems, drainage systems, etc. The purpose of each design is different.

Similarly in an enterprise software system, we have various aspects of design. Some of them are:

  1. Enterprise and deployment design
  2. Component design
  3. Class design
  4. User Interface design

Each of these deals with a different aspect of the software system and has different goals.

Enterprise design  addresses high level components like naming and directory servers, application server, messaging server, databases, clusters, high level components and their deployment. The purpose of enterprise and deployment design is to create a deployment that fulfills the performance, budget, connectivity, and scalability needs of the enterprise. An enterprise designed must understand the capability of application servers, databases, clusters and other services such as naming and directory services. He must be able to balance requirement with capabilities and costs. An enterprise designer needs to figure out which components get deployed on which servers and how they interact with each other.

Component design usually addresses using and creating reusable components. While creating a software system, we often have to make build vs. buy decisions for certain reusable components. If we come across functionality that we feel can be reused across projects, then we factor out that functionality into a separate component. Each component should ideally have clear responsibilities which should be represented by the public interface of a facade class. This facade class will serve as the point of interaction for the rest of the software system.

Class design deals with flexibility, extensibility, and maintainability. It is all about identifying classes, assigning responsibilities, and understanding how the classes will interact with each other to fulfill their responsibilities. Here is where we deal with concepts like loose coupling, inheritance, polymorphism, and software design patterns. To learn more about object oriented class design, you can refer to the free (under development) course on object oriented analysis and design hosted on our site.

User Interface design addresses usability issues of a software system. Through usability design we ensure that the user interface is intuitive and easy to use. It should be easy and quick to do common tasks, and impossible to do things the user is not allowed to do. It should present information in a way that is easy to use.

All of these are various aspects of software design. Each has a specific goal and a process to achieve good design. 

Comments

Popular posts from this blog

Running your own one person company

Recently there was a post on PuneTech on mom's re-entering the IT work force after a break. Two of the biggest concerns mentioned were : Coping with vast advances (changes) in the IT landscape Balancing work and family responsibilities Since I have been running a one person company for a good amount of time, I suggested that as an option. In this post I will discuss various aspects of running a one person company. Advantages: You have full control of your time. You can choose to spend as much or as little time as you would like. There is also a good chance that you will be able to decide when you want to spend that time. You get to work on something that you enjoy doing. Tremendous work satisfaction. You have the option of working from home. Disadvantages: It can take a little while for the work to get set, so you may not be able to see revenues for some time. It takes a huge amount of discipline to work without a boss, and without deadlines. You will not get the benefits (insuran

Some thoughts on redesigning education

Some time back I read a blog post on redesigning education. It asked some very good questions. Stuff which I had been thinking of myself. I left my thoughts on the blog, but I would also like to start a conversation around these ideas with those who read this blog as well. I would like to know what other people think of the issue of redesigning (college) education. I have often thought about how college education can be improved. To answer this question, we first have to ask a very basic question. What is the purpose of education? To me, we need education for 3 things: To learn more about the world around us To lead positive constructive lives To earn a good living / fulfill our ambitions I think education has to a large extent evolved to fulfill #3 (with a bias towards earning a comfortable living). The semester system, along with multiple choice tests, and grading, has made our education system into an assembly line. Students are pushed into the assembly line, given classes, admini

Testing Groovy domain classes

If you are trying to test Grails domain class constraints by putting your unit test cases in the 'test/unit' directory, then your tests will fail because the domain objects will not have the 'valdate' method. This can be resolved in two ways: Place the test cases inside test/integration (which will slow things down) Use the method 'mockForConstraintsTests(Trail)' to create mock method in your domain class and continue writing your test cases in 'test/unit' What follows is some example code around this finding. I am working on a Groovy on Grails project for a website to help programmers keep up and refresh their skills. I started with some domain classes and then moved on to write some unit tests. When we create a Grails project using grails create-app , it creates several directories, one of which is a directory called 'test' for holding unit tests. This directory contains two directories, 'unit', and 'integration' for uni