Package net.sf.eBus.messages

Class EMessage

java.lang.Object

net.sf.eBus.messages.EMessageObject

net.sf.eBus.messages.EMessage

All Implemented Interfaces:

java.io.Serializable

Direct Known Subclasses:

ENotificationMessage, EReplyMessage, ERequestMessage, ESystemMessage

public abstract class EMessage
extends EMessageObject
implements java.io.Serializable

EMessage is the base class for all eBus messages and contains the message subject and timestamp. Application messages do not extend this class directly but one of the subclasses: ENotificationMessage, ERequestMessage, or EReplyMessage.

Note: messages are limited to 31 fields. This is due to eBus binary serialization format. This number is decreased to 29 fields for sub-classes because EMessage used two fields: subject and timestamp. The work-around to this limitation is to group fields into an EField subclass, which is allowed to have 31 fields of its own. So if a message class uses two EField subclasses, it may contain up to 62 fields with 31 in each field subclass.

Note: a EMessage subclass may be used as a message field itself. That means that a message may contain another message as a field.

This class is immutable.

See EMessageObject for detailed explanation of the required builder inner class.

Author:

Charles Rapp

See Also:

EMessageHeader, EMessageObject, ENotificationMessage, ERequestMessage, EReplyMessage, EField, Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	EMessage.Builder<M extends EMessage,B extends EMessage.Builder<M,?>>	Base class for all EMessage builders.
static class	EMessage.MessageType	Messages are divided into four types: notification, request, reply and system.

Field Summary

Fields

Modifier and Type	Field	Description
static int	MAX_SUBJECT_LENGTH	eBus subjects are restricted to 512 characters.
java.lang.String	subject	The required message subject.
long	timestamp	The message timestamp in Java millisecond epoch time.

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	EMessage(EMessage.Builder<?,?> builder)	Creates a new eBus message based on the given message builder.

Method Summary

Modifier and Type	Method	Description
boolean	equals(java.lang.Object o)	Returns true if o is a non-null EMessage instance with a subject and timestamp equal to this EMessage instance and false otherwise.
int	hashCode()	Returns the message header hash code.
boolean	isApplicationMessage()	Returns true if this is an application message and false otherwise.
boolean	isSystemMessage()	Returns true if this is a system message and false otherwise.
EMessageKey	key()	Returns the unique message key based on the message class and subject.
EMessage.MessageType	messageType()	Returns the message type.
java.time.Instant	timestampAsInstant()	Returns message timestamp as an Instant rather than as an epoch millisecond long.
java.lang.String	toString()	Returns message subject and timestamp as a string.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

MAX_SUBJECT_LENGTH

public static final int MAX_SUBJECT_LENGTH

eBus subjects are restricted to 512 characters. eBus messages with subjects exceeding this limit cannot be created or de-serialized.

See Also:

Constant Field Values

subject

public final java.lang.String subject

The required message subject. The subject and the message class are used to route this message to the intended eBus clients.

timestamp

public final long timestamp

The message timestamp in Java millisecond epoch time.

Constructor Detail

EMessage

protected EMessage(EMessage.Builder<?,?> builder)

Creates a new eBus message based on the given message builder. builder is guaranteed to contain a valid message configuration at this point.

Parameters:

builder - contains the eBus message configuration.

Method Detail

equals

public boolean equals(java.lang.Object o)

Returns true if o is a non-null EMessage instance with a subject and timestamp equal to this EMessage instance and false otherwise.

Overrides:

equals in class java.lang.Object

Parameters:

o - comparison object.

Returns:

true if the message fields are equal and false otherwise.

hashCode

public int hashCode()

Returns the message header hash code.

Overrides:

hashCode in class java.lang.Object

Returns:

the message header hash code.

toString

public java.lang.String toString()

Returns message subject and timestamp as a string.

Overrides:

toString in class java.lang.Object

Returns:

the message as text.

key

public EMessageKey key()

Returns the unique message key based on the message class and subject.

Returns:

the unique message key based on the message class and subject.

messageType

public EMessage.MessageType messageType()

Returns the message type.

Returns:

the message type.

isSystemMessage

public boolean isSystemMessage()

Returns true if this is a system message and false otherwise. Only eBus is allowed to transmit a system message.

Returns:

true if this is a system message and false otherwise.

isApplicationMessage

public boolean isApplicationMessage()

Returns true if this is an application message and false otherwise.

Returns:

true if this is an application message and false otherwise.

timestampAsInstant

public java.time.Instant timestampAsInstant()

Returns message timestamp as an Instant rather than as an epoch millisecond long.

Returns:

message timestamp as Instant.