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kuni katsuya

Dependency injection discourages object-oriented programming? @ Blog of Adam Warski - 0 views

www.warski.org/...es-object-oriented-programming

java javaee6 CDI CdiDependencyInjection OO Object-Oriented procedural DI DependencyInjection

shared by kuni katsuya on 12 Dec 12 - No Cached
  • Dependency injection discourages object-oriented programming?
  • if you’re using DI, and you have an X entity, do you have an XService or XManager with lots of method where X is the first argument?
    • kuni katsuya
      kuni katsuya on 12 Dec 12
       
      evidence of the anti-pattern of procedural design in a java ee6 cdi application
  • previous way is more procedural
    • kuni katsuya
      kuni katsuya on 12 Dec 12
       
      ie. ProductService.ship(Product,Customer)
  • ...12 more annotations...
  • service/manager is a set of procedures you can run, where the execution takes a product and a customer as arguments
  • better
  • OO approach
  • not saying that achieving the above is not possible with a DI framework
  • only that DI
  • encourages the ProductService approach
    • kuni katsuya
      kuni katsuya on 12 Dec 12
       
      well, dependency injection, but moreover, the soa approach to service design tends to force otherwise intelligent software engineers into doing procedural design the services just end up being bags of method calls that implement any type of behavior, with the domain objects or entity beans being reduced to mere data structures with little responsibility or behavior beyond persistence. (which, in this anti-pattern, is typically mostly provided by the repository or dao class! ie. domain object crud)
  • it’s just easier
    • kuni katsuya
      kuni katsuya on 12 Dec 12
       
      ... if you just blindly follow the anti-pattern, of course  ;)
  • many benefits
    • kuni katsuya
      kuni katsuya on 12 Dec 12
       
      with the procedural approach, you also cannot implement polymorphic behavior, for instance
  • builder
  • fluent interface
  • it’s not for small projects
    • kuni katsuya
      kuni katsuya on 12 Dec 12
       
      fuckwhat? small or big matters not. if di is applied poorly, regardless of project size, it's an anti-pattern! disregard these comments!
  • problems with DI frameworks:
    • kuni katsuya
      kuni katsuya on 12 Dec 12
       
      not sure i agree with these points, but will refuse in a later sticky note
kuni katsuya

Dependency Injection in Java EE 6 - Part 1 - 0 views

www.theserverside.com/...-Injection-in-Java-EE-6-Part-1

javaee6 DependencyInjection DI

shared by kuni katsuya on 13 Sep 12 - Cached
  • Dependency Injection in Java EE 6 - Part 1
  • high-level look at CDI, see how it fits with Java EE overall and discuss basic dependency management as well as scoping.
  • CDI is designed to solve
  • ...21 more annotations...
  • highly type-safe
  • consistent
  • portable
  • CDI enhances the Java EE programming model in two more important ways
  • allows you to use EJBs directly as JSF backing beans
  • CDI allows you to manage the scope, state, life-cycle and context for objects in a much more declarative fashion, rather than the programmatic way
  • CDI has no component model of its own
  • set of services that are consumed by Java EE components such as managed beans, Servlets and EJBs.
  • well-defined create/destroy life-cycle that you can get callbacks for via the @PostConstruct and @PreDestroy annotations.
  • Managed beans
  • @ManagedBean
  • annotation
  • CDI also integrates with JSF via EL bean name resolution
  • CDI does not directly support business component services such as transactions, security, remoting, messaging
  • Dependency Injection for Java
  • JSR 330
  • JSR 330 defines a minimalistic API for dependency injection solutions and is primarily geared towards non-Java EE environments.
  • Figure 1 shows how CDI fits with the major APIs in the Java EE platform.
  • none of this uses string names that can be mistyped and all the code is in Java and so is checked at compile time
  • Qualifiers
  • are additional pieces of meta-data that narrow down a particular class when more than one candidate for injection exists
kuni katsuya

Dependency Injection in Java EE 6: Conversations (Part 4) - 0 views

www.theserverside.com/...Java-EE-6-Conversations-Part-4

javaee6 DependencyInjection DI

shared by kuni katsuya on 13 Sep 12 - Cached
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