Hello!

This is a simple app for the college that uses Replication as a technique to deal with Fault Tolerance in distributed systems scenario.

Testing

If it's possible, I recommend you to use Python 3.5+ to run this application.

Creating a virtual environment

Make sure that you have virtualenv installed in your machine too. After that, create an environment and give a name to him, like this:

virtualenv venv

Activating

With your virtual environment created. Activate him with:

source venv/bin/activate

Installing dependencies

With your environment activated, try to use pip to install the libraries:

pip install -r requirements.txt

Running

First let the pyro name server running to start the server:

python -m Pyro4.naming

Open another terminal, than activate your environment to start the master server:

python server.py

The same could be do with the client:

python client.py

Choose the desired option from the client menu:

• 1 - to echo a message
• 2 - list all messages
• 0 - exit the app

Then you can open as many server terminals you want, and close them just by pressing CTRL + C at the terminal and the data will still be consistent using the running servers

Deactivating environment

If you close the terminal everything should be closed, but if you wish to close the environment, try to use:

deactivate

To do

• Allow call echo method on echo server, it takes as arg the message to be returned as a echo
• Get already echoed messages list, this operation allow call getListOfMsg at echo servers to get the list of messages already sent by the clients
• Reply the operations to other replica servers, the server can call a replica to other replica servers
• Client can call the echo method on master server and this server can foward this call with the message to replica servers
• Tell the replica server quantity on server start

Requirements

• Allow N replica servers
• Every server (master and replicas) should mantain all received message that can be called by the client with getListOfMsg method
• If master server is down, the calling of echo method and getListOfMsg should be done to the next replica server and not be perceived by the user
• Instantiate the server before the client
• Ensure the server code is unique

Optional

• The replica servers quantity should be equal the quantity the code is executed by the command line or steps below
• Use a list of remote object name that represent the replica server
• Allow users to kill the first server of list
• The first name of list could be the master server
• When a new server is instantiated with a especific name of object, it should be added to the end of list