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

Styling Sort Icons Using Font Awesome for Primefaces' Data Table

So far, Primefaces has used image sprites for displaying the sort icons. This leads to a problem if we want to make a different style for these icons; for example, I would make the icon "arrow up" more blurry at the first time the table loading because I want to highlight the icon "arrow down". I found a way that I can replace these icons with Font Awesome icons. We will use "CSS Pseudo-classes" to achieve it. The hardest thing here is that we should handle displaying icons in different cases. There is a case both "arrow up" and "arrow down" showing and other case is only one of these icons is shown. .ui-sortable-column-icon.ui-icon.ui-icon-carat-2-n-s { background-image: none; margin-left: 5px; font-size: 1.1666em; position: relative; } .ui-sortable-column-icon.ui-icon.ui-icon-carat-2-n-s:not(.ui-icon-triangle-1-s)::before { content: "\f106"; font-family: "FontAwesome"; position: ...

PSMDB - A MongoDB alternative for having Encryption At Rest

Encryption is the most popular tool for securing data both in transit and at rest. - For protecting data in transit, we can configure to use the TLS connection - For protecting data at rest, we can use Percona Server for MongoDB (PSMDB), an open-source alternative for MongoDB Enterprise. License PSMDB Docker images follow the SSPL license. Therefore, it is not a problem when I only have my containers deployed in on-premises environments. Running MongoDB Replication on OpenShift I have successfully installed the replication by following the guide Install Percona Server for MongoDB on OpenShift . In order to make it work properly with my needs, I disabled some features from the default deployment. See the detail in this change Basically, I needed to create a CRD (Custom Resource Definition) to let OpenShift/Kubernetes what PSMDB is. Then, I deployed the Operator pod. Finally, I deployed the PSMDB StatefulSet. I used NFS shares for Persistent Volumes. Create CRD for PSMDB 2 git clone http...

Building Axon.ivy Projects on Bitbucket Pipelines

Read me if you don't know what Axon.ivy (Ivy) is. Motivation - Ivy projects are designed to be built on a continuous integration (CI) server like Jenkins - Today, Bitbucket supports for CI with Bitbucket Pipelines - We're using Bitbucket. Then, why not? It must be very cool and convenient for us if we can centralize our CI and VCS (version control system) tools in one place. Here is an approach We have to use a maven plugin called project-build-plugin to build ivy projects. This plugin requires an instance of Ivy engine during building time. Bitbucket Pipelines allows us to specify our own docker image as a build environment. What we need to do is to prepare our docker image with needed stuffs such as JDK, Maven, Ivy engine, etc. Step 1. Prepare Docker images For testing purpose, I already created two docker images: Maven and Axon.ivy engine. They are now available on Docker Hub This image for Maven using Oracle JDK 8 This image for Axon.iv...

Creating a Chatbot with RiveScript in Java

Motivation "Artificial Intelligence (AI) is considered a major innovation that could disrupt many things. Some people even compare it to the Internet. A large investor firm predicted that some AI startups could become the next Apple, Google or Amazon within five years" - Prof. John Vu, Carnegie Mellon University. Using chatbots to support our daily tasks is super useful and interesting. In fact, "Jenkins CI, Jira Cloud, and Bitbucket" have been becoming must-have apps in Slack of my team these days. There are some existing approaches for chatbots including pattern matching, algorithms, and neutral networks. RiveScript is a scripting language using "pattern matching" as a simple and powerful approach for building up a Chabot. Architecture Actually, it was flexible to choose a programming language for the used Rivescript interpreter like Java, Go, Javascript, Python, and Perl. I went with Java. Used Technologies and Tools Oracle JDK 1.8...

Improving the execution time of CI pipelines

Executing a large number of tests, especially integration tests, takes a lot of time. For instance, the pipeline of one of our projects for each Pull Request previously took nearly 30 minutes, including over 1 thousand test cases. This article guides you through several good techniques that we have discovered and applied to improve the time-consuming process. Parallel stages Analyze the current phases in your pipeline and categorize them in parallel. For example, we can separate the build and verify code of Node.js and Maven modules simultaneously in our Jenkins pipelines. Please mind using the setting failFast whether you want to abort the pipeline immediately. Read more: Parallel stages with Declarative Pipeline 1.2 (jenkins.io) Parallel test execution If you use Maven, t he plugin maven-failsafe-plugin is used to execute integration tests during phases integration-test and verify the build lifecycle. It allows us to execute tests in parallel. There are many settings related ...

vhandit

Search This Blog