Overview

Plexus personalities give you the capability to customize how your component lifecycle works. You can mix and match personalities within Plexus to meet your needs. There is the core Plexus personality for "Plexus Components" as well as personalities for Avalon and PicoContainer

Which personality you should use depends on your needs. If you are just starting, you will most likely want to use the Plexus personality. However, each personality has it's own pros and cons.

The natural question which might be asked: isn't this a bad idea to mix component personalities? The answer is simple: it is usually better to use single component personality,, but sometimes you have no choice. A component is not necesserly a simple class which you can write in 5 minutes. There are much more complex components: LDAP servers, Servlet Containers, Embeddable databases etc. For example Apache James (Java mail server) and quite a lot of other components which might be useful for someone were writen in accordance with Avalon API. Plexus gives you as possiblity to reuse those components in your applications.

The Relation between Component Profile and Component Personality

Component Personality is an implementation of the contract which must be fulfilled by the container in order to allow it to run components which were written in accordance to that contract (API).

Component Profile provides more convinent, shorter syntax for declaring component descriptors

Each component profile will contain information about the following:

• component factory
• component composer
• lifecycle handler
• manager

  These are used for managing a given component inside the container. Implemenation of those services may already exist or be provided by an implementation of component personality. For example a list of component managers (instantiation strategies) provided by Plexus is quite complete and there is pratically no need for writing new component manager. But situation looks much different for component lifecycles. Avalon and Pico components have their own lifecycles and implemenation of phases of those lifecycles had to be made for Plexus.

  Without component profile users will have to do:

  <component>
    ....
    <component-factory>pico</component-factory>
    <component-composer>noop</component-composer>
    <lifecycle-handler>pico</lifecycle-handler>
  <component>

  with component profile:

  <component>
    ....
    <profile>pico</profile>
  <component>

  It (will be) is possible to override default values of choosen attributes defined in component profile. For example for pico component which should have instaniation-strategy = "per-lookup" you can just do:

  <component>
    ....
    <profile>pico</profile>
    <instantiation-strategy>per-lookup</instantiation-strategy>
  <component>