Controls Versioning Model

Overview

There are important use cases for controls where the various related artifacts (interfaces, extensions, implementations) are developed by different people/organizations, and as those artifacts evolve over time it becomes useful to be able to specify versioning information and require certain version values. The controls programming model features a number of annotations to support this.

Defining a Version

package org.apache.beehive.controls.api.versioning;

public @inteface Version
{
    int major();
    int minor() default 0;
}

The @V'*_ersion annotation:

  • Is allowed on control interfaces (annotated with @C_*'ontrolInterface).
  • Defines a version of the control interface and is the basis of controls versioning.
  • Is retained in interface class file (not BeanInfo!)

Specifying Version Restrictions/Requirements

package org.apache.beehive.controls.api.versioning;

public @interface VersionRequired
{
    int major;
    int minor default -1;
}

The @V'*_ersionRequired annotation:

  • Is allowed on control extensions and controls field declarations.
  • Defines the minimum versions of the control interface that this extension or field requires.
  • Major version mandatory, minor is optional (default is to not require any specific minor ver).
  • When extension or client is compiled, version requirement is enforced against the control interface found at that time.
  • When extension's control bean is is classloaded, version requirement is statically enforced against the control interface found at that time. 
public @interface VersionSupported
{
    int major;
    int minor default -1;
}

The @V_*'ersionSupported annotation:

  • Is allowed on control implementations.
  • Defines the maximum versions of the control interface that this implementation supports.
  • Major version mandatory, minor is optional (default is to support all minor versions).
  • When implementation is compiled, version requirement is enforced against the control interface found at that time.
  • When implementation is classloaded, version requirement is statically enforced against the control interface found at that time.

Open Issues

  • Static runtime enforcement may run into problems in complex classloader situations (where interfaces and impls come from different classloaders). Perhaps add a way to disable runtime checks?
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