The <type> element is an assembly of descriptors of the constraints a component type declares towards a container and includes declaration of service dependencies, Logger establishment criteria, Configuration, Parameters and Context establishment criteria, in addition to human-readable information about the component type.

Configuration instances supplied to the builder shall correspond to the type DTD. The structure of a Type XML document is described below:

  <!--
  Example of a component meta info external XML form. The 
  element contains the information required to construct an 
  instance of org.apache.avalon.meta.info.Type.  It 
  includes information about the component type, the service 
  it provides, and the services it is dependent on.
  -->

  <type>


    <!--
    Definition of a single component info descriptor.
    -->

    <info>

      <!-- the name of the component (character restrictions apply) -->

      <name>my-component</name>

      <!-- the implementation version -->

      <version>1.2.1</version>

      <!-- the set of attributes associated with the type
         (attribute names and values are examples only) -->

      <attributes>

         <attribute key="color" value="blue"/>
         <attribute key="quantity" value="35"/>

      </attributes>

    </info>

    <!--
    The set of logging categories the component uses. 
    -->

    <loggers>

      <logger name="store"/>
      <logger name="store.cache"/>
      <logger name="verifier"/>
    
    </loggers>


    <!-- 
    Declaration of the context constraints for the compoent type. 
    The "type" attribute is the name of an interface derived from the default
    context interface org.apache.avalon.framework.context.Context 
    -->

    <context type="MyContextInterface">

      <!-- 
      Declaration of an entry in a context object, the "key" is
      the key used by a component to locate the context entry,
      the "type" is the classname of value (typically an interface)
      or primitive type.  The default value is java.lang.String.
      The "optional" attribute is a boolean value derived from the 
      TRUE or FALSE that indicates if the context value must be 
      provided or not (default is FALSE). 
      -->

      <entry key="base" type="java.io.File"/>
      <entry key="mode" optional="TRUE"/>

    </context>

    <!--
    Declaration of the set of services that this component is capable 
    of supplying.  Each service declared under the services element
    may be referenced by other component info descriptions as a 
    dependency.  A container is responsible for the assembly of 
    components based on the connection of supplier components to 
    consumer components via a common service description. 
    -->

    <services>

      <!-- 
      The service element declares the classname of an service 
      interface and the version identifier that qualify as the service 
      version.  The default version value is 1.0.
      -->

      <service>

        <reference type="SimpleService" version="3.2">

        <attributes>

           <!--
           Attributes qualifying as service implementation may be included
           as supplementary information to the attributes declared under
           a ServiceDefinition.
           -->

        </attributes>

      </service>

    </services>


    <!-- 
    Declaration of the set of dependencies that this component type has on 
    component suppliers.  Dependency declarations define the role name 
    that the component will use to access a service via a service
    or component manager.  A dependency may be declared as optional by 
    setting the optional attribute value to TRUE.  The default value 
    for optional is FALSE.
    -->

    <dependencies>

      <!-- 
      A dependency declaration. In the following example the optional 
      attribute is redundant as it is equivalent to the default value
      but is included here for completeness.
      -->
  
      <dependency optional="FALSE"
  
        key="my-transformer"
        type="org.apache.cocoon.api.Transformer
        version="1.1">

        <!-- the set of attributes associated with the dependency -->

        <attributes>

           <!-- 
           ServiceDefintion constraints may be included under the 
           attributes element.
           -->

        </attributes>

      </dependency>

    </dependencies>

  </type>