Agile Methodology:Insights

What Is Agile?

The Agile movement proposes alternatives to traditional project management. Agile approaches are typically used in software development to help businesses respond to unpredictability.

What is Scrum?

Scrum has only three roles: Product Owner, Team, and Scrum Master. These are described in detail by the Scrum Training Series. The responsibilities of the traditional project manager role are split up among these three Scrum roles. Scrum has five meetings: Backlog Grooming (aka Backlog Refinement), Sprint Planning, Daily Scrum (aka 15-minute standup), the Sprint Review Meeting, and the Sprint Retrospective Meeting.Scrum is the most popular way of introducing Agility due to its simplicity and flexibility. Because of this popularity, many organizations claim to be “doing Scrum” but aren’t doing anything close to Scrum’s actual definition. Scrum emphasizes empirical feedback, team self management, and striving to build properly tested product increments within short iterations. Doing Scrum as it’s actually defined usually comes into conflict with existing habits at established non-Agile organizations.

Many books and classes are available from a variety of competing sources of varying accuracy and quality.  One place to start would be the Scrum Training Series, which uses an entertaining approach to cover the most popular way of introducing Agile to teams. You can also download the 6-page illustrated Scrum Reference Card.

What’s Wrong With Traditional Approaches?

In 1970, Dr. Winston Royce presented a paper entitled “Managing the Development of Large Software Systems,” which criticized sequential development. He asserted that software should not be developed like an automobile on an assembly line, in which each piece is added in sequential phases, each phase depending on the previous. Dr. Royce recommended against the phase based approach in which developers first gather all of a project’s requirements, then complete all of its architecture and design, then write all of the code, and so on. Royce specifically objected to the lack of communication between the specialized groups that complete each phase of work.

It’s easy to see the problems with the waterfall method. It assumes that every requirement can be identified before any design or coding occurs. Could you tell a team of developers everything that needed to be in a software product before any of it was up and running? Or would it be easier to describe your vision to the team if you could react to functional software? Many software developers have learned the answer to that question the hard way: At the end of a project, a team might have built the software it was asked to build, but, in the time it took to create, business realities have changed so dramatically that the product is irrelevant. Your company has spent time and money to create software that no one wants. Couldn’t it have been possible to ensure the end product would still be relevant before it was actually finished?

Today very few organizations openly admit to doing waterfall or traditional command and control. But those habits persist.

Why Agile?

Agile development provides opportunities to assess the direction throughout the development lifecycle. This is achieved through regular cadences of work, known as Sprints or iterations, at the end of which teams must present a potentially shippable product increment. By focusing on the repetition of abbreviated work cycles as well as the functional product they yield, agile methodology is described as “iterative” and “incremental.” In waterfall, development teams only have one chance to get each aspect of a project right. In an agile paradigm, every aspect of development — requirements, design, etc. — is continually revisited. When a team stops and re-evaluates the direction of a project every two weeks, there’s time to steer it in another direction.

This “inspect-and-adapt” approach to development greatly reduces development costs and time to market. Because teams can develop software at the same time they’re gathering requirements, “analysis paralysis” is less likely to impede a team from making progress. And because a team’s work cycle is limited to two weeks, stakeholders have recurring opportunities to calibrate releases for success in the real world. Agile development helps companies build the right product. Instead of committing to market a piece of software that hasn’t been written yet, agile empowers teams to continuously replan their release to optimize its value throughout development, allowing them to be as competitive as possible in the marketplace. Agile development preserves a product’s critical market relevance and ensures a team’s work doesn’t wind up on a shelf, never released.

source:http://agilemethodology.org/

Difference between @Component and @Configuration?

@Component and @Configuration are indeed very different types of annotations.

@Component and similar annotations (@Service, @Repository, etc. )and its JSR-330 counterpart @Named allow you to declare beans that are to be picked up by autoscanning with<context:component-scan/> or @ComponentScan they register the bean definition for the classes, so they are roughly equivalent to declaring the specified beans with the <bean ... /> tag in XML. This bean types will adhere to the standard proxy creation policies.

@Configuration annotation was designed as the replacement of the XML configuration file. To create @Configuration annotated beans, Spring will always use CGLIB to subclass the @Configurationannotated class, overriding its @Bean annotated method to replace it with the bean lookup method to make singleton beans to be created only once. (Spring does not use CGLIB to intercept internalmethod calls of normal Spring beans, it creates a separate instance of proxy instead(same way like JDK proxy does). Doing so allows to use proxies to avoid cardinality mismatch - for example a proxy singleton can fetch current session bean, which is not possible with class inheritance only. ). Despite that, @Configuration annotated classes are still able to use annotated(@Autowired, @Inject etc.) fields and properties to request beans (and even other @Configuration annotated beans too) from the container.

Example from 4.12.5 section of the documentation

@Configuration
public class AppConfig {

  @Bean
  public ClientService clientService1() {
    ClientServiceImpl clientService = new ClientServiceImpl();
    clientService.setClientDao(clientDao());
    return clientService;
  }
  @Bean
  public ClientService clientService2() {
    ClientServiceImpl clientService = new ClientServiceImpl();
    clientService.setClientDao(clientDao());
    return clientService;
  }

  @Bean
  public ClientDao clientDao() {
    return new ClientDaoImpl();
  }
}

in the example above only one ClientDao instance will be created.