net.jxta.platform
Class ModuleClassID

java.lang.Object
  |
  +--net.jxta.id.ID
        |
        +--net.jxta.platform.ModuleClassID

All Implemented Interfaces:

java.lang.Cloneable, java.io.Serializable

public abstract class ModuleClassID

extends ID

This interface defines a Module Class Identifier. A ModuleClassID uniquely identifies a particular local behaviour, that is, a specific API for each execution environment for which an implementation exists.

A ModuleClassID has two components: A base class identifier, and a role identifier. The role identifier may be zero. By convention the API uses the ModuleClassID with a zero role identifier to designate the base class in contexts where only the base class is significant. Nonetheless, a ModuleClassID with a zero role identifier is a valid ModulesClassID wherever a full ModuleClassID is expected. In many cases, only one role in a given class is ever used. Using role zero in such cases is an optimization because it may make the string representation of the ModuleClassID shorter.

Each service of a group, that is, the role it plays in the group, is uniquely identified per the group definition. This identifier may be used by other modules in the group to designate this one, or by the service itself to identify its parameters in a PeerAdvertisement. In addition, by combining its PeerGroupID with its own ModuleClassID, a service may create a predictible identifier unique on their peer, suitable for registering listeners with the EndpointService or other services with similar listener interfaces.

The standard PeerGroup implementation of the java reference implementation assigns to each service its ModuleClassID as its unique service identifier. Most of the times this ModuleClassID is a base classID, but groups that use the same Module Class for more than one service (same behaviour but playing a different role in the group, such as, for example, a data base engine with a different data base), may define multiple roles identified by the same base class identifier but different role identifiers. The standard PeerGroup implementation of the java reference implementation has the notion of main application: a default application which may be started automatically upon instantiating the group. This application implements Module and, therefore, is assigned a ModuleClassID. However applications are not expected to play any specific role in the group. As a result, they are assigned a role identifier allocated at run-time as need to garantee local unicity. As a result main applications cannot expect a predictible ClassID.

A ModuleClassID is optionaly described by a published ModuleClassAdvertisement.

There may be any number of embodiements of a module class. These are module specifications. A module specification represent the network behaviour of a module while its class represents its local behaviour. Different groups may use a common subset of classes, for example, the basic set defined by the platform should always be part of it. Each group may use different and network-incompatible specifications for common classes, optimized for various purposes. The local API of a given class on a given JXTA implementation will be invariant per the spec being used. Therefore, the difference will be transparent to applications which do not depend on the possibly different quality of service.

A ModuleSpecID embeds a base class identifier, which permits to verify that a given Module specification is suitable for its intended use.

Since:

JXTA 1.0

Version:

$Revision: 1.2 $

See Also:

PeerGroup, Module, ModuleClassID, PeerAdvertisement, ModuleSpecAdvertisement, ModuleClassAdvertisement, EndpointService, ID, Serialized Form

Fields inherited from class net.jxta.id.ID

nullID, URIEncodingName, URNNamespace

Constructor Summary

ModuleClassID()

Method Summary

abstract ModuleClassID	getBaseClass() Return a ModuleClassID of the same base class but with the role portion set to zero.
abstract boolean	isOfSameBaseClass(ModuleClassID id) Returns true if this ModuleClassID is of the same base class than the given class.
abstract boolean	isOfSameBaseClass(ModuleSpecID id) Returns true if this ModuleClassID is of the same class than the the given ModuleSpecID.

Methods inherited from class net.jxta.id.ID

clone, getIDFormat, getUniqueValue, getURL, toString

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ModuleClassID

public ModuleClassID()

Method Detail

isOfSameBaseClass

public abstract boolean isOfSameBaseClass(ModuleClassID id)

Returns true if this ModuleClassID is of the same base class than the given class. Note: This method is NOT named "isOfClass" because a ModuleClassID may have two UUID; one that denotes a "base" class proper, and an optional second one that denotes a "Role", or subclass. Compatibility between ClassIDs is based on the "base" portion, hence the "isOfSame" naming. This routine can be used for comparison with a base class since a base class is just a class which role portion happens to be zero.

Parameters:

id - Module class id to compare with

Returns:

boolean true if equals

Since:

JXTA 1.0

isOfSameBaseClass

public abstract boolean isOfSameBaseClass(ModuleSpecID id)

Returns true if this ModuleClassID is of the same class than the the given ModuleSpecID.

Parameters:

id - Module spec id to compare with

Returns:

boolean true if equals

Since:

JXTA 1.0

getBaseClass

public abstract ModuleClassID getBaseClass()

Return a ModuleClassID of the same base class but with the role portion set to zero. aka "the base class".

Returns:

ModuleClassID the base class.