org.lsst.ccs.bus.messages

Class BusMessage<T extends Serializable,D>

java.lang.Object

org.lsst.ccs.bus.messages.BusMessage<T,D>

Type Parameters:

T - Template class for the embedded object. It must be Serializable.

D - Template class for the encoded object

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

CommandMessage, LogMessage, StatusMessage

public abstract class BusMessage<T extends Serializable,D>
extends Object
implements Serializable

Base class for messages sent on the buses. Concrete implementations (command, status and log messages) will be sent on the appropriate bus. Each BusMessage wraps a Serializable Object to be sent over the buses. Of this Object it contains its byte code representation and its Encoded version. The return value of the encoding process depends on the different subclasses. Refer to their documentation for more information. Clients receiving this message can choose to use the encoded version of the embedded Object (which is always available), or, if they have the class definition of the embedded Object, use the de-serialized version of the Object. The embedded object is serialized and encoded when the BusMessage is serialized, i.e. right before being shipped over the buses. Additional information contained by the BusMessage:

• class name: the class of the embedded object
• AgentInfo : the information of the Agent from which the message originated
• creation timestamp : the timestamp in CCS milliseconds of when the BusMessage was created

This information can be used to filter on the bus messages.

Author:

LSST CCS Team

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
BusMessage(T obj) Build a BusMessage from the provided Object.

Method Summary

Modifier and Type	Method and Description
protected abstract D	encodeObject(T obj) Subclasses must provide a specific implementation of the encoding process.
String	getClassName() Get the class name of the embedded object.
D	getEncodedData() Get the Encoded version of the embedded Object.
T	getObject() Get the original version of the embedded Object.
AgentInfo	getOriginAgentInfo() The Origin of the BusMessage, the bus registration name of the Agent from which it originated.
long	getTimeStamp() Get the timestamp in CCS milliseconds of when the message was created.
void	setOriginAgentInfo(AgentInfo agent) Sets the origin for this BusMessage.
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

BusMessage

public BusMessage(T obj)

Build a BusMessage from the provided Object. The provided object can be null, in which case no serialization or encoding occurs.

Parameters:

obj - The Serializable object to be sent over the buses.

Method Detail

encodeObject

protected abstract D encodeObject(T obj)

Subclasses must provide a specific implementation of the encoding process.

Parameters:

obj - The Serializable object embedded in the BusMessage.

Returns:

The encoded version of the embedded object.

getClassName

public String getClassName()

Get the class name of the embedded object.

Returns:

The class name of the embedded Object.

getEncodedData

public D getEncodedData()

Get the Encoded version of the embedded Object.

Returns:

The Encoded version of the embedded Object.

getObject

public T getObject()

Get the original version of the embedded Object.

Returns:

The de serialized version of the embedded Object

Throws:

RuntimeException - if the embedded object cannot be de-serialized.

getOriginAgentInfo

public AgentInfo getOriginAgentInfo()

The Origin of the BusMessage, the bus registration name of the Agent from which it originated.

Returns:

The origin of this BusMessage.

setOriginAgentInfo

public final void setOriginAgentInfo(AgentInfo agent)

Sets the origin for this BusMessage. This method should only be used internally, by the MessagingLayer Architecture. It must not be used by users/developers.

Parameters:

agent - The origin of the BusMessage.

getTimeStamp

public long getTimeStamp()

Get the timestamp in CCS milliseconds of when the message was created.

Returns:

The creation time in CCS milliseconds.

toString

public String toString()

Overrides:

toString in class Object