com.aquenos.epics.jackie.common.protocol

Class ChannelAccessSearchClientMessage

java.lang.Object

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

com.aquenos.epics.jackie.common.protocol.ChannelAccessSearchMessage

com.aquenos.epics.jackie.common.protocol.ChannelAccessSearchClientMessage

public final class ChannelAccessSearchClientMessage
extends ChannelAccessSearchMessage

Representation of a CA_PROTO_SEARCH message that is sent from a client to a UDP or TCP server in order to find the location of a channel.

Author:

Sebastian Marsching

See Also:

ChannelAccessCommand.CA_PROTO_SEARCH

Field Summary

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

command, originalMessageHeader

Constructor Summary

Constructors

Constructor and Description
ChannelAccessSearchClientMessage(int cid, ChannelAccessVersion version, boolean doReply, java.lang.String channelName) Creates a new CA_PROTO_SEARCH message that can be sent from a client to a UDP or TCP server.

Method Summary

Modifier and Type	Method and Description
protected static ChannelAccessSearchClientMessage	deserialize(ChannelAccessMessageHeader messageHeader, ByteSource byteSource, boolean headerOnly, java.nio.charset.Charset charset) 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	getChannelCID() Returns the channel ID that is used by the client to identify the channel.
java.lang.String	getChannelName() Returns the channel name that the client is looking for.
ChannelAccessVersion	getVersion() Returns the Channel Access version supported by this client.
int	hashCode() Returns a hash code value for this message.
boolean	isDoReply() Returns the "do reply" flag.
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

ChannelAccessSearchClientMessage

public ChannelAccessSearchClientMessage(int cid,
                                        ChannelAccessVersion version,
                                        boolean doReply,
                                        java.lang.String channelName)

Creates a new CA_PROTO_SEARCH message that can be sent from a client to a UDP or TCP server.

Parameters:

cid - client-side identifier for this channel.

version - Channel Access protocol version supported by the client.

doReply - true if the client also wants to be informed if the requested channel could not be resolved, false if the client only wants to receive messages with the channel location. This flag might be ignored by some servers, which will have the same effect as if it were set to false.

channelName - name of the channel the client is looking for.

Method Detail

getChannelCID

public int getChannelCID()

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

Returns:

client-side ID for the channel.

getChannelName

public java.lang.String getChannelName()

Returns the channel name that the client is looking for.

Returns:

channel name. Might be null if this message instance has been reconstructed without its payload (as part of the payload of an error message).

isDoReply

public boolean isDoReply()

Returns the "do reply" flag. This flag indicates that the client wants to be informed by the server if the server does not know the channel the client is looking for. By default, a server will only reply to a search request if it knows the channel the client is looking for. Even if this flag is set, some servers might ignore it and not reply to search requests that they cannot provide an answer for.

Returns:

true if the client wants to be informed by a server if the channel is not known, false if it only wants to be informed if the channel was found.

getVersion

public ChannelAccessVersion getVersion()

Returns the Channel Access version supported by this client. A server can use this information in order to decide whether to reply to a search request. For example, a server might not reply to a search request if the protocol version supported by the client is too old for the server.

Returns:

Channel Access version supported by the client.

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.

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).

deserialize

protected static ChannelAccessSearchClientMessage deserialize(ChannelAccessMessageHeader messageHeader,
                                                              ByteSource byteSource,
                                                              boolean headerOnly,
                                                              java.nio.charset.Charset charset)

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).

headerOnly - if true this method will not try to read the payload but just read the header. This is useful for reading a message that is sent in the payload of a ChannelAccessErrorMessage. Such a message will have all headers but no payload (even so the payload size might be non-zero).

charset - encoding to use for deserializing the channel name. Usually, channel names should consist of ASCII characters only, however this is not strictly enforced by the protocol, so the encoding might matter.

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.