Class WireMessage (0.7.0)

public abstract class WireMessage

Generic representation for a wire message, generally executed by calling send.

Inheritance

java.lang.Object > WireMessage

Inherited Members

Object.clone()

Object.equals(Object)

Object.finalize()

Object.getClass()

Object.hashCode()

Object.notify()

Object.notifyAll()

Object.toString()

Object.wait()

Object.wait(long)

Object.wait(long,int)

Static Methods

getParameters(DataInputStream input)

protected static byte[][] getParameters(DataInputStream input)

Extracts parameters/arguments from the user input.

Parameter

Name	Description
input	`DataInputStream` The data stream containing the user request.

Returns

Type	Description
byte[][]	A byte array of user-defined parameters to be bound.

Exceptions

Type	Description
Exception	If reading fails in any way.

Constructors

WireMessage(ConnectionHandler connection, int length)

public WireMessage(ConnectionHandler connection, int length)

Parameters

Name	Description
connection	`ConnectionHandler`
length	`int`

Fields

connection

protected ConnectionHandler connection

Field Value

Type	Description
ConnectionHandler

inputStream

protected DataInputStream inputStream

Field Value

Type	Description
DataInputStream

length

protected int length

Field Value

Type	Description
int

outputStream

protected DataOutputStream outputStream

Field Value

Type	Description
DataOutputStream

Methods

getHeaderLength()

protected int getHeaderLength()

How many bytes is taken by the payload header. Header is defined here as protocol definition + length. Most common value here is four bytes, so we keep that as default. Effectively, this is how much of the message you "don't" want to read from the message's total length with readAll.

Returns

Type	Description
int	The remaining length to be processed once "header" information is processed.

getIdentifier()

protected abstract String getIdentifier()

Used for logging.

Returns

Type	Description
String	Message Identifier (int for Bootstrap, char otherwise).

getMessageName()

protected abstract String getMessageName()

Used for logging.

Returns

Type	Description
String	The official name of the wire message.

getPayloadString()

protected abstract String getPayloadString()

Used for logging.

Returns

Type	Description
String	Payload metadata.

nextHandler()

public void nextHandler()

Some messages may have some more context and require some order. This handles state machine setting for ConnectionHandler.

Exceptions

Type	Description
Exception

read(int length)

public String read(int length)

Reads a fixed-length string from the saved stream. The string still needs to be null-terminated, but the read is more efficient, as we can read the entire string in one go instead of continuously checking for a null-terminator.

Parameter

Name	Description
length	`int` The number of bytes to read.

Returns

Type	Description
String	the string.

Exceptions

Type	Description
IOException	if an error occurs while reading from the stream, or if no null-terminator is found at the end of the string.

readAll()

protected String readAll()

Read the remainder of the received message. To be called once metadata for the message is read. Metadata is designated as type, length, etc.

Returns

Type	Description
String	The remainder of the message in String format.

Exceptions

Type	Description
Exception	If reading fails in any way.

readString()

public String readString()

Reads a null-terminated string from a DataInputStream. Note that though existing solutions for this exist, they are either not keyed exactly for our use case, or would lead to a more combersome addition to this codebase. Also note the 128 byte length is chosen from profiling and determining that it exceeds the 90th percentile size for inbound messages.

Returns

Type	Description
String	the string.

Exceptions

Type	Description
IOException	if an error occurs while reading from the stream, or if no null-terminator is found before the end of the stream.

send()

public void send()

Once the message is ready, call this to send it across the wire. Effectively a template pattern.

Exceptions

Type	Description
Exception	If the sending fails.

sendPayload()

protected abstract void sendPayload()

Override this method to include post-processing and metadata in the sending process. Template method for send.

Exceptions

Type	Description
Exception	If any step in output message fails.

toString()

public String toString()

Returns

Type	Description
String

Overrides

Object.toString()