A brief overview about Software Design and Software architecture

What is Software Design and Architecture? How they relate and differ each other?

To try to understand Software Design/Architecture, we can do an analogy using a project of a house, for example:

Software Architecture

As an architect, you would have high level concerns, such as:

• How many people does it needs to support?
• How many rooms does it have?
• How are they connected / accessible?
• What would be the best house position, angle, size?
• What is the region where the house is located?
• What materials should I use for that region?

These are higher level questions and show interactions of many “components” on a wide scope.

So during the architecture we need to know:

• The big picture of the problem we need to solve.
• What are the possible solutions.
• Define how the “overall” solution would look like.
• Raise the Necessary requirements for an stable and long living solution.
• Define the quality tradeoffs.

What is a quality trade-off?

A tradeoff happens when to make an improvement you must sacrifice some other quality, for example: Adding security layer even if it costs some performance, makes the application safer.

What are important skills for a Software Architect?

• Tech Skills: Having good years of experience programing with different languages, databases, frameworks, solving problems in different scales, etc are mandatory.
  • Design patterns.
  • Code standards.
  • Distributed processing.
  • Network.
  • Event Oriented and Object Oriented Programing.
  • …Any other Technology close to your professional scope. Example: An architect for mobile apps, must know cloud computing, mobile programing (i.e. Java), UI and so on.

• Business knowledge: An architect must be close to the business in order to clearly understand their needs and find the better approach to create a successful solution.

• Organizational skills: Handle multiple concerns: Security, Performance, Business requirements, technical limitations, deadlines, etc.

• Soft skills: It’s true that we use computers to create our applications, but we actually work with people for people. It’s important to maintain good relationship with colleagues from the team and other departments. Make the work environment pleasant and collaborative. Happy people produce more and do not get sick so often.

• Know what is available: Do not get stuck on your technologies and ideas. Always try to find out what is happening in the market, which technologies are available, what can you use? I mean, you do not need to know everything in details, but it comes handy when you have a problem to solve and plenty of alternatives to nail it.

As an Architect it is necessary to interact, collect feedback and meet the stakeholders expectations.

Who are the Stakeholders and how the Software Architect interacts to them?

• Developers: The role of Architect is to provide a direction, organization and conceptual integrity for the developers towards to achieve the company goals in the better way possible.

• Project Managers: The architect must inform the Project Manager about risks, dependencies, impact, task’s responsible and so.

• Clients: Clients are the reason the system exists, cause they are funding it. The Architect must keep communication with clients to collect feedback and assure the system is being build according to their expectations.

• End users: Users do not care (and might not even understand) how the software is built, but they care it is working properly. An architect must know the software is meeting to end users expectations and support the proper functional and no functional requirements to improve it.

Software Design

Still considering the house project as example, the “Design” involves a low level scope, which means, we can can go on details for a given component.

Considering we need to build the kitchen, now the questions are:

• How would the person interact with the kitchen?
• How many sinks and which sizes we would need?
• For plumbing, which pipes should we use, and in which disposition?
• What will be the best material for this type of kitchen?
• How would be better electrical wires connections to use, and how many plugs and sockets?

When we enter in “implementation” details of a “component” we are talking about the design.

But what are the Stages of the Software Design?

Stage 1: Conceptual Design

This part is closer to the software behavior and functional validation.

• Concept validation: Collect and validate customer requirements.
• Conceptual mockups: Create mockups to help you visualize your problems in the earlier stage.
• Validate mockups: Show, validate and adapt your mockups with the customers.
• Create the CRC cards: Class Responsibility Collaborator cards will help you identify classes and components in your system and how they interact each other.
• Reveal “hidden” questions: During the previous steps, many questions might come to you. Bring them to the customer, before moving forward.

What is CRC (Class Responsibility Collaborator)?

This technique helps you see the relations between classes or components.

• Class or Component: The class or components that interact with other class or components.
• Responsibilities: The responsibilities of this component.
• Collaborators: Components this component interacts with.

Stage 2: Technical Design

This part is closer to the software implementation.

• Go into details: Turn the conceptual design into a more precise design, for example, start the UML class diagram.
• Programing Define code structure and turn mockups into classes and then an application.

Categories of objects

During the technical design, many types of objects will be evidenced:

• Entity Objects: Real world entities that know their rules and attributes. Example: Customer.
• Boundary objects: Objects responsible to collect / send information to other systems. Example: Gateway, ContactForm.
• Control objects: Objects that control other objects. Example: “Mediator”.

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