moses.message
Class Message

java.lang.Object
  |
  +--moses.message.Message

All Implemented Interfaces:

java.lang.Cloneable

public class Message

extends java.lang.Object

implements java.lang.Cloneable

This class represents in a single object all the messages that can possibly circulate between agent-controller, controller-controller and controller-external_member.

The class only offers two methods concerned with serialization and deserialization of a message to and from a DataInput(Output)Stream (Java default serialization mechanism is not an efficient alternative).

The class has a polymorphic behavior. It declares a pool of variable, representing all the possible fields in all the possible messages, and a number of indicator flags (int). Depending on the value of the flags, only certain variables in the pool actually store values (the rest are null).

All the messages start with an integer value, indicating the number of bytes that follow in the message (body length). It follows a byte value indicating the type of message (all types are defined in moses.util.Const class), followed by an int value indicating the message unique sequence number. The subsequent values depend on the type of the message.
A list of all messages and their serial layout is presented bellow:

agent-controller communication:
-------------------------------------------------------------------------
send
|I:b-size|B:type|I:seq_no|B:p_type|S:source|S:dest|...
SND| SPLD| |S:s_payload|
OPLD| |O:o_payload|
BPLD| |I:plen |B[]:b_payload|
send_exp
|I:b-size|B:type|I:seq_no|B:p_type|S:source|S:dest|...
SNDE| SPLD| |S:s_payload|S:s_lname|
OPLD| |O:o_payload|S:s_lname|
BPLD| |I:plen |B[]:b_payload|S:s_lname|
send_ack
|I:b-size|B:type|I:seq_no|
ACK
send_cert
|I:b-size|B:type|I:seq_no|S:source|O:cert|
CERT
send_self_cert
|I:b-size|B:type|I:seq_no|S:source|O:cert||I:plen |B[]:sign |
SCERT
adopt
// |I:b-size|B:type|I:seq_no|B:a_type|B:l_type|S:source|S:pwd|S:law|S:arg1|S:arg2| |I:b-size|B:type|I:seq_no|B:l_type|S:source|S:pwd|S:law|S:arg1|S:arg2|B[]:sign ("sign" saves the certifeid list see CertVerifierList) |
ADOPT
reconnect
|I:b-size|B:type|I:seq_no|S:source|S:pwd|
RECON
test
|I:b-size|B:type|I:seq_no|S:source|S:arg1|S:arg2|
TEST
change_password
|I:b-size|B:type|I:seq_no|S:pwd|S:opwd|
CHPWD
change_password_answer
|I:b-size|B:type|I:seq_no|B:status|
CHPWDA
adopt_answer
|I:b-size|B:type|I:seq_no|B:status|
ADANS
adopt_answer_certified
|I:b-size|B:type|I:seq_no|O:cert||I:plen |B[]:sign |
ADANSC

controller-controller communication:
-------------------------------------------------------------------------
forward
|I:b-size|B:type|I:seq_no|B:p_type|S:source|S:dest|
FWD| SPLD| |S:s_payload |S:s_hash|S:s_lname|S:d_hash|
OPLD| |O:o_payload |S:s_hash|S:s_lname|S:d_hash|
BPLD| |I:plen|B[]:b_payload|S:s_hash|S:s_lname|S:d_hash|
controller
|I:b-size|B:type|I:seq_no|
CNTR

controller_cert
|I:b-size|B:type|I:seq_no|S:source|O:cert||I:plen |B[]:sign |
CNTRCERT

create
// |I:b-size|B:type|I:seq_no|B:a_type|B:l_type|S:dest|S:pwd|S:law|S:arg1|S:arg2|S:source|S:s_lname|S:s_hash|
|I:b-size|B:type|I:seq_no|B:l_type|S:dest|S:pwd|S:law|S:arg1|S:arg2|S:source|S:s_lname|S:s_hash|
CRT

exception
|I:b-size|B:type|I:seq_no|B:ex_po|...
EXC|
FWD|B:p_type|S:source|S:dest|...
SPLD| |S:s_payload |S:d_hash|S:fcause|
OPLD| |O:o_payload |S:d_hash|S:fcause|
BPLD| |I:plen|B[]:b_payload|S:d_hash|S:fcause|
//ADOPT|B:a_type|B:l_type|S:source|S:pwd|S:law|S:arg1|S:arg2|S:fcause| // CRT|B:a_type|B:l_type|S:dest|S:pwd|S:law|S:arg1|S:arg2|S:source|S:s_lname|S:s_hash|S:fcause| CRT|B:l_type|S:dest|S:pwd|S:law|S:arg1|S:arg2|S:source|S:s_lname|S:s_hash|S:fcause|

controller-external_member communication:
-------------------------------------------------------------------------

submit
|I:b-size|B:type|I:seq_no|B:p_type|S:source|S:dest|I:sport|...
SBMT| SPLD| |S:s_payload|
OPLD| |O:o_payload|
BPLD| |I:plen |B[]:b_payload|
submitp
|I:b-size|B:type|I:seq_no|B:p_type|S:source|S:dest|I:sport|...
SBMTP| SPLD| |S:s_payload|S:pwd|
OPLD| |O:o_payload|S:pwd|
BPLD| |I:plen |B[]:b_payload|S:pwd|
submitc
|I:b-size|B:type|I:seq_no|B:p_type|S:source|S:dest|I:sport|...
SBMTC| SPLD| |S:s_payload|O:cert|
OPLD| |O:o_payload|O:cert|
BPLD| |I:plen |B[]:b_payload|O:cert|I:plen |B[]:sign |

error_message
|I:b-size|B:type|I:seq_no|I:status|
ERR

exmember
|I:b-size|B:type|I:seq_no|S:dest||I:sport|
EXM

Field Summary

java.lang.String	arg1 Holds the adoption argument supplied by the actor.
java.lang.String	arg2 Holds an extra adoption argument; not used at present time.
byte[]	b_payload Holds the byte array payload of this message according to the type of the message; null otherwise.
moses.security.LGICert	cert Holds the LGI certificate when such a certificate is exchanged during a particular message.
java.lang.String	d_hash The hash of the destination law.
static int	DEFAULT_AS Minimum default size of a message; it represents the preallocated space for a ByteArrayOutputStream
static int	DEFAULT_MAXS The maximum size allowed for a message.
java.lang.String	dest Holds the moses name of the destination of this message.
int	ex_po This field contains the type of the payload of the original message reported during an exception message.
java.lang.String	fcause Holds the failure cause during an exception message.
int	l_type Holds the type of the law referenced in this message; it is either Const.IMM or Const.URL.
java.lang.String	law Holds the law URL
java.lang.Object	o_payload Holds the Object payload of this message according to the type of the message; null otherwise.
java.lang.String	opwd Holds the old reconnection password during changing the password.
int	p_type Maintains the payload type: String, Object and byte array.
java.lang.String	pwd Holds the reconnection password of the actor.
java.lang.String	s_hash This field contains the hash of the law of the source of the message.
java.lang.String	s_lname The name of the law of the source of the message; necessary only as a suggestion, when the destination is not in the portal.
java.lang.String	s_payload Holds the String payload of this message according to the type of the message; null otherwise.
int	seq_no Maintains the message sequence number.
byte[]	sign Holds the signature of a self-certificate when such a certificate is exchanged during a particular message.
java.lang.String	source Holds the moses name of the source of this message.
int	sport Sender port for a submitted message.
int	status Status answer the controller reports to the actor.
int	type Variable maintaining the type of the message being sent.

Constructor Summary

Message()
The default constructor, allocates and initializes all necessary structures for a message.

Method Summary

moses.message.Message	copy() Copy itself into a new Message object.
static void	main(java.lang.String[] args)
void	read(java.io.DataInput dis) Read (deserializing) method: Considering the layout presented in the description of this class, first read the first Integer coming from the DataInputStream argument.
void	write_cached(java.io.DataOutput dos) Version of write method where data to serialized is assumed to have been previously cached in the "recv" byte array (perhaps from a previous read).
void	write(java.io.DataOutput dos) Write(serializing) method: initially resets a ByteArrayOutputStream object then proceeds in writing all the data into the byte array, according to the message layout.

Methods inherited from class java.lang.Object

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

Field Detail

type

public int type

Variable maintaining the type of the message being sent.

seq_no

public int seq_no

Maintains the message sequence number.

p_type

public int p_type

Maintains the payload type: String, Object and byte array.

source

public java.lang.String source

Holds the moses name of the source of this message.

dest

public java.lang.String dest

Holds the moses name of the destination of this message.

s_payload

public java.lang.String s_payload

Holds the String payload of this message according to the type of the message; null otherwise.

o_payload

public java.lang.Object o_payload

Holds the Object payload of this message according to the type of the message; null otherwise.

b_payload

public byte[] b_payload

Holds the byte array payload of this message according to the type of the message; null otherwise.

cert

public moses.security.LGICert cert

Holds the LGI certificate when such a certificate is exchanged during a particular message.

sign

public byte[] sign

Holds the signature of a self-certificate when such a certificate is exchanged during a particular message.

l_type

public int l_type

Holds the type of the law referenced in this message; it is either Const.IMM or Const.URL.

pwd

public java.lang.String pwd

Holds the reconnection password of the actor.

opwd

public java.lang.String opwd

Holds the old reconnection password during changing the password.

law

public java.lang.String law

Holds the law URL

arg1

public java.lang.String arg1

Holds the adoption argument supplied by the actor.

arg2

public java.lang.String arg2

Holds an extra adoption argument; not used at present time.

status

public int status

Status answer the controller reports to the actor.

s_hash

public java.lang.String s_hash

This field contains the hash of the law of the source of the message.

s_lname

public java.lang.String s_lname

The name of the law of the source of the message; necessary only as a suggestion, when the destination is not in the portal.

d_hash

public java.lang.String d_hash

The hash of the destination law.

ex_po

public int ex_po

This field contains the type of the payload of the original message reported during an exception message.

fcause

public java.lang.String fcause

Holds the failure cause during an exception message.

sport

public int sport

Sender port for a submitted message.

DEFAULT_AS

public static final int DEFAULT_AS

Minimum default size of a message; it represents the preallocated space for a ByteArrayOutputStream

See Also:

Constant Field Values

DEFAULT_MAXS

public static final int DEFAULT_MAXS

The maximum size allowed for a message.

See Also:

Constant Field Values

Constructor Detail

Message

public Message()

The default constructor, allocates and initializes all necessary structures for a message. It should be used called to using a message object.

Method Detail

write

public void write(java.io.DataOutput dos)
           throws java.io.IOException

Write(serializing) method: initially resets a ByteArrayOutputStream object then proceeds in writing all the data into the byte array, according to the message layout. After the message has been written and flushed, retrieve the byte array out of ByteArrayOutputStream, then rewrite the first 4 bytes with the length of byte array - 4. Finally, send the byte array into the DataOutputStream argument.

Parameters:

dos - argument specifies the DataOutputStream where to write the message to.

java.io.IOException

read

public void read(java.io.DataInput dis)
          throws java.lang.Exception

Read (deserializing) method: Considering the layout presented in the description of this class, first read the first Integer coming from the DataInputStream argument. Then allocate a new byte array the size of that length and read the remaining data into that byte array. Once the byte array is available, transform it into a ByteArrayInputStream, then int a DataInputStream and read the remaining fields, according to the layout schema. This method maintains the original byte array buffer into a object field, such that a message that has been read can be written back into the connection without expensive serialization (caching functionality). In order to do that, the actual byte array allocated for reading is readInt()+4, and the initial 4 bytes would store the length of data to come.

Parameters:

dis - argument specifies the DataInputStream where to read the message from.

java.lang.Exception

write_cached

public void write_cached(java.io.DataOutput dos)
                  throws java.io.IOException

Version of write method where data to serialized is assumed to have been previously cached in the "recv" byte array (perhaps from a previous read).

It may be useful for forwarding unmodified messages carrying objects .

java.io.IOException

copy

public moses.message.Message copy()

Copy itself into a new Message object. This method is similar in fuctionality to a (deep) clone method.

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

java.lang.Exception