com.aquenos.epics.jackie.common.protocol

Class ChannelAccessCancelSubscriptionServerMessage

java.lang.Object

com.aquenos.epics.jackie.common.protocol.ChannelAccessMessage

com.aquenos.epics.jackie.common.protocol.ChannelAccessSubscriptionMessage

com.aquenos.epics.jackie.common.protocol.ChannelAccessCancelSubscriptionServerMessage

public final class ChannelAccessCancelSubscriptionServerMessage
extends ChannelAccessSubscriptionMessage

Representation of a CA_PROTO_EVENT_ADD message that is sent from a server to a client. This message is sent in response to a subscription cancellation request.

For some historic reasons, the server sends this message instead of a CA_PROTO_EVENT_CANCEL message in response to a ChannelAccessCancelSubscriptionClientMessage. The only way to tell this message apart from a ChannelAccessSubscriptionServerMessage is by its payload size. This message always has a zero payload size, while the ChannelAccessSubscriptionServerMessage always has a non-zero payload size.

Author:

Sebastian Marsching

See Also:

ChannelAccessCommand.CA_PROTO_EVENT_ADD, ChannelAccessSubscriptionClientMessage, ChannelAccessSubscriptionServerMessage, ChannelAccessCancelSubscriptionClientMessage

Field Summary

Fields inherited from class com.aquenos.epics.jackie.common.protocol.ChannelAccessMessage

command, originalMessageHeader

Constructor Summary

Constructors

Constructor and Description
ChannelAccessCancelSubscriptionServerMessage(ChannelAccessValueType dataType, int count, int sid, int subscriptionId) Creates a CA_PROTO_EVENT_ADD message.

Method Summary

Modifier and Type	Method and Description
protected static ChannelAccessCancelSubscriptionServerMessage	deserialize(ChannelAccessMessageHeader messageHeader, ByteSource byteSource) Constructs a message from a header and a byte source.
boolean	equals(java.lang.Object obj) Tells whether the specified object represents the same message.
int	getChannelSID() Returns the channel ID that is used by the server to identify the channel.
int	getCount() Returns the number of elements the value in this message's payload has.
ChannelAccessValueType	getDataType() Returns the data type of the value in this message's payload.
int	getSubscriptionId() Returns the client-assigned subscription ID.
int	hashCode() Returns a hash code value for this message.
protected void	serialize(ByteSink byteSink, ChannelAccessVersion version, int maxPayloadSize, java.nio.charset.Charset charset) Serializes this message to a byte sink.
java.lang.String	toString() Returns a string representation of this message.
protected void	verify(ChannelAccessVersion version, int maxPayloadSize, java.nio.charset.Charset charset) Verifies that this message can be serialized.

Methods inherited from class com.aquenos.epics.jackie.common.protocol.ChannelAccessMessage

addByteArrayToStringBuilder, calculatePaddingSize, getCommand, getOriginalMessageHeader, hasOriginalMessageHeader, serializeHeader, verifyHeader

Methods inherited from class java.lang.Object

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

Constructor Detail

ChannelAccessCancelSubscriptionServerMessage

public ChannelAccessCancelSubscriptionServerMessage(ChannelAccessValueType dataType,
                                                    int count,
                                                    int sid,
                                                    int subscriptionId)

Creates a CA_PROTO_EVENT_ADD message. This constructor should be used to create a message that is sent from a server to a client in response to a ChannelAccessCancelSubscriptionClientMessage sent by the client.

Parameters:

dataType - data type sent in the client's request.

count - count sent in the client's request.

sid - the channel identifier used by the server.

subscriptionId - client-assigned subscription ID. This ID must be the same ID that was sent with the client's request.

Method Detail

getDataType

public ChannelAccessValueType getDataType()

Returns the data type of the value in this message's payload. This should always match the data type that the client requested. Returns null if the specified data-type is unknown to this implementation.

Returns:

data-type of the value or null if the numeric identifier cannot be mapped to a data type known by this implementation.

getCount

public int getCount()

Returns the number of elements the value in this message's payload has. This should always match the element count that the client requested.

Returns:

number of value elements.

getChannelSID

public int getChannelSID()

Returns the channel ID that is used by the server to identify the channel. This integer may be zero or negative.

Returns:

server-side ID for the channel.

getSubscriptionId

public int getSubscriptionId()

Returns the client-assigned subscription ID. The subscription ID is used by the client in order to map events sent in response to a subscription to the respective subscription. This must always be the ID that was sent by the client. This number might be negative or zero.

Returns:

client-assigned subscription identifier.

serialize

protected void serialize(ByteSink byteSink,
                         ChannelAccessVersion version,
                         int maxPayloadSize,
                         java.nio.charset.Charset charset)

Description copied from class: ChannelAccessMessage

Serializes this message to a byte sink. This method is only intended to be used by ChannelAccessMessageCodec.

Specified by:

serialize in class ChannelAccessMessage

Parameters:

byteSink - byte sink that is used for writing the serialized data.

version - protocol version to stay compatible with. This is the protocol version of the peer the message is sent to.

maxPayloadSize - maximum size of the payload.

charset - encoding to use for serializing the string data (e.g. channel names, error strings, string data-values).

verify

protected void verify(ChannelAccessVersion version,
                      int maxPayloadSize,
                      java.nio.charset.Charset charset)

Description copied from class: ChannelAccessMessage

Verifies that this message can be serialized. This method is only intended to be used by ChannelAccessMessageCodec.

Overrides:

verify in class ChannelAccessMessage

Parameters:

version - protocol version to stay compatible with. This is the protocol version of the peer the message is sent to.

maxPayloadSize - maximum size of the payload.

charset - encoding to use for serializing the string data (e.g. channel names, error strings, string data-values).

equals

public boolean equals(java.lang.Object obj)

Description copied from class: ChannelAccessMessage

Tells whether the specified object represents the same message.

Two messages are considered equal if they are of the same type and have the same headers and payload. For comparing the types, the actual Java type and not just the Channel Access command is compared.

Overrides:

equals in class ChannelAccessMessage

Parameters:

obj - reference object with which this object is compared.

Returns:

true if obj is a message that is of the same type and has the same headers and payload as this message. false if obj is null or of a different type than this message or differs in the headers or payload.

hashCode

public int hashCode()

Description copied from class: ChannelAccessMessage

Returns a hash code value for this message. This method is supported for the benefit of hash tables. The hash code is calculated as a combination of the hash codes of this messages headers (including the Channel Access command) and its payload (if present).

If two messages are equal (as indicated by the return value of ChannelAccessMessage.equals(Object)), they also have the same hash code. However, the fact that two messages have the same hash code does not imply that they are equal.

Overrides:

hashCode in class ChannelAccessMessage

Returns:

hash code suitable for use by a hash table.

toString

public java.lang.String toString()

Description copied from class: ChannelAccessMessage

Returns a string representation of this message. The string representation contains the messages command, its header fields (if relevant for the command type) and its payload if present.

Overrides:

toString in class ChannelAccessMessage

Returns:

string representation of this message.

deserialize

protected static ChannelAccessCancelSubscriptionServerMessage deserialize(ChannelAccessMessageHeader messageHeader,
                                                                          ByteSource byteSource)

Constructs a message from a header and a byte source. This method is only intended for use by ChannelAccessMessageCodec.

Parameters:

messageHeader - CA message header.

byteSource - byte source for reading the message's payload (if any).

Returns:

message constructed from the data in the header and the payload read from the byte source (if headerOnly is false).

Throws:

java.nio.BufferUnderflowException - if there is not enough data in the byte source to read the complete payload.

ShortPayloadException - if the message's payload size is less than the size needed for the data type and count.