org.opendaylight.controller.cluster.access.concepts

Class Message<T extends org.opendaylight.yangtools.concepts.WritableIdentifier,C extends Message<T,C>>

java.lang.Object

org.opendaylight.controller.cluster.access.concepts.Message<T,C>

Type Parameters:

T - Target identifier type

C - Message type

All Implemented Interfaces:

Serializable, org.opendaylight.yangtools.concepts.Immutable, org.opendaylight.yangtools.concepts.MutationBehaviour<org.opendaylight.yangtools.concepts.Immutable>

Direct Known Subclasses:

Request, Response

@Beta
public abstract class Message<T extends org.opendaylight.yangtools.concepts.WritableIdentifier,C extends Message<T,C>>
extends Object
implements org.opendaylight.yangtools.concepts.Immutable, Serializable

An abstract concept of a Message. This class cannot be instantiated directly, use its specializations Request and Response.

Messages have a target and a sequence number. Sequence numbers are expected to be assigned monotonically on a per-target basis, hence two targets can observe the same sequence number.

This class includes explicit versioning for forward- and backward- compatibility of serialization format. This is achieved by using the serialization proxy pattern. Subclasses are in complete control of what proxy is used to serialize a particular object on the wire. This class can serve as an explicit version marker, hence no further action is necessary in the deserialization path.

For the serialization path an explicit call from the user is required to select the appropriate serialization version. This is done via toVersion(ABIVersion) method, which should return a copy of this object with the requested ABI version recorded and should return the appropriate serialization proxy.

This workflow allows least disturbance across ABI versions, as all messages not affected by a ABI version bump will remain working with the same serialization format for the new ABI version.

Note that this class specifies the Immutable contract, which means that all subclasses must follow this API contract.

Author:

Robert Varga

See Also:

Serialized Form

Method Summary

Modifier and Type	Method and Description
protected com.google.common.base.MoreObjects.ToStringHelper	addToStringAttributes(com.google.common.base.MoreObjects.ToStringHelper toStringHelper) Add attributes to the output of toString().
protected abstract C	cloneAsVersion(ABIVersion targetVersion) Create a copy of this message which will serialize to a stream corresponding to the specified method.
long	getSequence() Get the logical sequence number.
T	getTarget() Get the target identifier for this message.
ABIVersion	getVersion()
String	toString()
C	toVersion(ABIVersion toVersion) Return a message which will end up being serialized in the specified ABIVersion.
protected Object	writeReplace()

Methods inherited from class java.lang.Object

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

Method Detail

getTarget

@Nonnull
public final T getTarget()

Get the target identifier for this message.

Returns:

Target identifier

getSequence

public final long getSequence()

Get the logical sequence number.

Returns:

logical sequence number

getVersion

@Nonnull
public final ABIVersion getVersion()

toVersion

@Nonnull
public final C toVersion(@Nonnull
                                  ABIVersion toVersion)

Return a message which will end up being serialized in the specified ABIVersion.

Parameters:

toVersion - Request ABIVersion

Returns:

A new message which will use ABIVersion as its serialization.

cloneAsVersion

@Nonnull
protected abstract C cloneAsVersion(@Nonnull
                                             ABIVersion targetVersion)

Create a copy of this message which will serialize to a stream corresponding to the specified method. This method should be implemented by the concrete final message class and should invoke the equivalent of Message(Message, ABIVersion).

Parameters:

targetVersion - target ABI version

Returns:

A message with the specified serialization stream

Throws:

IllegalArgumentException - if this message does not support the target ABI

toString

public final String toString()

Overrides:

toString in class Object

addToStringAttributes

@Nonnull
protected com.google.common.base.MoreObjects.ToStringHelper addToStringAttributes(@Nonnull
                                                                                           com.google.common.base.MoreObjects.ToStringHelper toStringHelper)

Add attributes to the output of toString(). Subclasses wanting to contribute additional information should override this method. Any null attributes will be omitted from the output.

Parameters:

toStringHelper - a MoreObjects.ToStringHelper instance

Returns:

The MoreObjects.ToStringHelper passed in as argument

Throws:

NullPointerException - if toStringHelper is null

writeReplace

protected final Object writeReplace()