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https://github.com/sakurasound/final_messenger


https://github.com/sakurasound/final_messenger

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README 

        
Currently trying to fix up… There are bugs… I will try to get as many fixed as i can before end of semester.



There already are two jars for you to use to run the client and server



call "java -jar Client.jar to run client"

call "java -jar Server.jar  " to run the server



if you want to build the files use ant to build the files...

if you want to run the resulting build, for now you go into the 

bin folder and call java Client or java Server  



***** HOW IT WORKS *****

CLIENT

Client is a running process (single threaded) that allows the user

to type in a series of commands to interact with a server.

There are 10 different commands that have been implemented (or waiting)

How to use them can be seen in the menu of the client class



Server - Adds server information to the system. Can optionally add 

         a name of a data store that you want to communicate with

Show   - (Yet to be implemented) Shows the open data stores on server

Insert - Allows user to insert a record into a data store on a server

Delete - Allows user to delete a record from a data store on a server

Find   - Allows user to find set of records from a data store 

Test   - Allows user to ping a server to see if it is up and running

Switch - Allows user to switch to a different data store on the same 

         server. If no name give, switches to the temporary store on

         the server. If a name is given, allows user to create a new

         data store with the next operation on the server

Link   - Allows user to link two servers together. (This is based on names

		 given in the record store using insert).

Unlink - Allows user to unlink two servers using alias names on server

Register Allows user to register themself to a server to accept incoming

         messages

Unregis - Allows user to unregister themselves, so they cannot accept

          incoming messages

Send   - Allows user to send another client a message

List   - Allows user to see registered users (not fully implemented)

         Currently uses regex and the server_name (port number right now).

Kill   - Allows user to kill a data store if name is given, otherwise

         kills all data stores currently running on the server, and then

         shuts down server

Help   - Does just what the name suggests

Close  - Closes client



SERVER

The server is a multithreaded process that has several key components

ServerThread  - The main thread of execution, responsible for accepting

                requests from clients using a non-blocking mechanism

Demultiplexor - Takes request from client, and places it in proper 

                record store (data store). These data stores are accessed

				via ConcurrentHashMap.

RecordStore   - Referred to as a data store, these thread(s) is responsible for

                a set of records (persistent or transient). Accepts requests

                sent from the Demultiplexor, and runs them. Resulting messages

                are sent to the client directly from the RecordStore.

                If a name was given to this record store, it persists on close

                and information is stored in the data folder, with a .dat extension

                Each job turns into an appropriate task. Records are stored in 

				a CopyOnWriteArrayList to allow concurrency on reads

				during writes. We allow reads during writes, but only one write

				at a time in order to maintain some lineage with the data

				(no branching of list history).

ReadTask      - These thread(s) are responsible for reads on a data store

WriteTask     - These thread(s) are responsible for writes on a data store

DeleteTask    - These thread(s) are responsible for deletes on a data store



***** PROTOCOL USED *****

Messages being passed between client and server utilize the JAXB

(Java Xml Bindings) protocol. There are a series of message objects

that are passed between the client and server carrying information.

The messages are serialized to XML before being passed through the

sockets. The idea behind this is that in a scenario where you have

clients and servers running and do not know the implementation of

the other side (client running python, server running java), it 

allows for the data to be defined in a way where it is still able

to function regardless of language. 



comm.msg

IMMessage

LinkMessage

DeleteMessage - Called when deleting a record from a data store

ReadMessage   - Called for finding messages on a data store

WriteMessage  - Called for adding a new message to a data store

ErrorMessage  - Called when an error arises on server

TestMessage   - Called when pinging for server existance

KillMessage   - Called when wanting to kill a data store or server



comm.resp

DeleteResponseMessage     - Sent when Delete was successful

ReadListMessage           - Sent when Find message was successful

ReadResponseMessage       - Sent after receiving ReadListMessage was 

                            Successful

WriteResponseMessage      - Sent when adding new record was successful

TestResponseMessage       - Sent when a server receives a ping message

KillResponseMessage       - Sent when closing a data store on server is 

                            successful

BatchKillResponseMessage  - Sent when closing all data stores and server is

                            successful.



****** TESTING USED ********

A series of tests were written using JUnit4 that primarily tested the 

durability of the RecordStore, the message passing system, as well as

each of the tasks. A few multithreaded tests were written too, but due

to the complexity of these types of tasks, they are somewhat trivial.



Improvement: for the next iteration, I need to clean up the clientlist 

             bug and tune up the updating system... i know there are some

             bugs to be removed for those two...