Agile Design

How can you design the software which is built in tiny increments?

How can you ensure that the software has a good structure which is flexible, maintainable and reusable?

ARE'NT YOU GOING TO MISS THE BIG PICTURE?

Not really! In an agile team, the big picture evolves along with the software.

How? With each iteration, the team improves the design of the system so that it is as good as it can be for the system as it is now. They focus on the current structure of the system, making it as good as it can be.

How do we know if the design of software is good?

Avoiding these following symptoms of poor design (design smells) should be a way.

1. Rigidity - The design is hard to change.
2. Fragility - The design is easy to break.
3. Immobility - The design is hard to reuse.
4. Viscosity - It is hard to do the right thing.
5. Needless Complexity - Overdesign
6. Needless Repetition - Mouse abuse
7. Opacity - Disorganized expression

These symptoms are similar in nature to code smells, but they are at a higher level. They are smells that pervade the overall structure of the software rather than a small section of code.

How to avoid design smells?

The principles of object-oriented design that help developers eliminate design smells and build the best designs for the current set of features.

1. SRP - The Single Responsibility Principle
2. OCP - The Open-Closed Principle
3. LSP - The Liskov Substitution Principle
4. DIP - The Dependency Inversion Principle
5. ISP - The Interface Segregation Principle

These principles are not the product of a single mind, but they represent the integration of the thoughts and writings of a large number of software developers and researchers.

Agile teams apply principles to remove smells. They don't apply principles when there are no smells.

Often, a design smell is caused by the violation of one or more of the principles.

Principles are not a perfume to be liberally scattered all over the system. Overconformance to the principles leads to the design smell of Needless Complexity.

Reference:
Image result for agile software development book

Image result for agile software development book

Robert C.Martin, Agile Software Development, Principles, Patterns, and Practices; Section 2, Agile Design.

Comments

Junit - Test fails on French or German string assertion

In my previous post about building a regex to check a text without special characters but allow German and French . I met a problem that the unit test works fine on my machine using Eclipse, but it was fail when running on Jenkins' build job. Here is my test: @Test public void shouldAllowFrenchAndGermanCharacters(){ String source = "ÄäÖöÜüß áÁàÀâÂéÉèÈêÊîÎçÇ"; assertFalse(SpecialCharactersUtils.isExistSpecialCharater(source)); } Production code: public static boolean isExistNotAllowedCharacters(String source){ Pattern regex = Pattern.compile("^[a-zA-Z_0-9_ÄäÖöÜüß áÁàÀâÂéÉèÈêÊîÎçÇ]*$"); Matcher matcher = regex.matcher(source); return !matcher.matches(); } The result likes the following: Failed tests: SpecialCharactersUtilsTest.shouldAllowFrenchAndGermanCharacters:32 null A guy from stackoverflow.com says: "This is probably due to the default encoding used for your Java source files. The ö in the string literal in the J...

How to apply Lean - Kanban for your business

This is the topic of Scrum Breakfast meetup this time, speaker: Ms. Phuong Bui - Technical Project Manager of YOOSE Pte. Ltd. http://www.meetup.com/Scrum-Breakfast-Vietnam-Agile-and-Scrum-Meetup/events/230313727/ Lean comes from Lean manufacturing is a method that focuses on elimination of wastes. In other words, this is a set of principles for archiving the quality, speed and customer alignment. The first time I knew about the term "Lean" is from the book Software Craftsmanship . Sandro recommends if we want to transform our pet projects into a real business, we should get familiar with Lean Startup concepts. In this talk, Ms. Phuong pointed out some major wastes includes information (ex: unclear requirements), processes (ex: waiting), physical environment and people. Knowing what the problems should be the best way to eliminate them. The difference between Single item flow and Batch processing is the second main point; and it is the Lean's idea. Batch pr...

The HelloWorld example of JSF 2.2 with Myfaces

I just did by myself create a very simple app "HelloWorld" of JSF 2.2 with a concrete implementation Myfaces that we can use it later on for our further JSF trying out. I attached the source code link at the end part. Just follow these steps below: 1. Create a Maven project in Eclipse (Kepler) with a simple Java web application archetype "maven-archetype-webapp". Maven should be the best choice for managing the dependencies , so far. JSF is a web framework that is the reason why I chose the mentioned archetype for my example. 2. Import dependencies for JSF implementation - Myfaces (v2.2.10) into file pom.xml . The following code that is easy to find from http://mvnrepository.com/ with key words "myfaces". <dependency> <groupId>org.apache.myfaces.core</groupId> <artifactId>myfaces-api</artifactId> <version>2.2.10</version> </dependency> <dependency> <groupId>org.apache.myfaces.core<...

MS SQL Server Views

"Creates a virtual table whose contents (columns and rows) are defined by a query. Use this statement to create a view of the data in one or more tables in the database. For example, a view can be used for the following purposes: - To focus, simplify, and customize the perception each user has of the database. - As a security mechanism by allowing users to access data through the view, without granting the users permissions to directly access the underlying base tables. - To provide a backward compatible interface to emulate a table whose schema has changed." [1] Beside that, our team used view in order to improve the performance of our web apps when a database has a very complicated relationship between its tables by using ORM Frameworks such as Hibernate. Example code: --create CREATE VIEW placeholders AS SELECT EMPKEY AS empkey, CONNUMB AS connumb, EMPNBR AS empNbr, ACEEMPN AS empFirstName, ACEEMPFN AS empLastName, EMPNAM AS empFullName, ...

Think like a Engineering Manager

Off-boarding Members can leave the company for various reasons, and as a manager, it is important to take action. Hoping for the best is not a strategy. In the case of a low-performing member, I can kindly issue an official warning, set clear objectives for improvement, and re-evaluate the results. If there is a conflict between members, I need to be mindful and go beyond the situation to list our expectations with corresponding actions. Finally, if a member has a big chance to grow at another company, I can have an honest discussion with that member about the trade-offs. Balance at Work As an engineering manager, it is important to balance involvement in meetings and getting your hands dirty on some topics. The goal is to become a companion to teams. Here are my two actions to deal with the situation: Dedicate time for important-but-not-urgent tasks and prioritize them daily. Categorize work into four lines including management, project support, OKRs, and self-study. Management Conduc...

vhandit

Search This Blog