Notification System (Twitter clone)

Notification System (Twitter clone) is a distributed system to handle sending and receving of notifications. It's divided in three type of process:

• Client (./src/client/app_client.cpp): the client process is used by users to follow other users, send and receive notifications.
• Front-end (./src/frontend/app_frontend.cpp): this process goal is to allow the communications between Client apps and ReplicaManager servers.
• ReplicaManager (./src/server/app_server.cpp): implements passive replication. It's responsible to process the requests, send back responses and keep all the data consistency among all backup replicas.

Contributors

• Alencar da Costa
• Filipe Faria Dias
• Raphael Scherpinski

Tech

This repo uses a number of known techs to work properly:

• C++ (std=C++11)
• Sockets API (POSIX)
• ncurses (v6.2)

Compilation

1. In case you haven't installed nurses yet, you can install it by running this command sudo apt-get install libncurses-dev
2. Then, to compile all three apps run: make in the root directory of the project
3. The executable can be found at ./build

Apps execution

Client

In the root directory of the project run ./build/app_client <username>. <username> is the identifier of the user you want to log in and must starts with @ and have at least 4 characters.

Example: ./build/app_client @alencar

It's super important to config the terminal that you are going execute the client process, in order to be able to visualize the client app correctly. The terminal must have at least 24 rows and 100 columns.

How to use the client app

The client app is very simple, it has three commands: Send requests/commands: To send a request/command to the notification server, it's required to select the command input box and, to do so, you can press the key c. This will move the cursor to the command box and then you can start writing your commands. In order to send the typed command press Enter and to leave the command box press F1.

Currently, there are two commands available: SEND and FOLLOW. To follow other user the command to use is: FOLLLOW <username> where <username> is the identifier of the user you want to follow. Remember: the identifier begins with @ and has at least 4 characters. Example: FOLLOW @student. To send a notification to all your followers execute SEND <message> where <message> is your notification message. Example: SEND Hello, world!.

Read old notifications: In order to read old notifications that were scrolled down in the Notification Box, you can press n and use the keys Up arrow and Down arrow to navigate in the Notification Box. To leave the notification box you need to press F1.

Close the app: To close the app you can press the key F1 when you are outside any box.

Front-end

In the root directory of the project run ./build/app_frontend. The front-end will init and try to start a server in one available addresses that were confiured in the file /src/GlobalConfig.hpp.

ReplicaManager

To init the first ReplicaManager that will automatically start as leader run ./build/app_server <port>. It will start the internal communication TCP server at 0.0.0.0:<port> and the notification server at 0.0.0.0:8080. You can change the IP used by replicas and port used by the notification server in the file src/server/config.hpp by changing the value of the defined macros DEFAULT_IP and DEFAULT_SERVER_PORT.

And to init other backup replicas yu can run ./build/app_server <port> <current_leader_port> where <port> is the port used by the new replica for the internal communication and <current_leader_port> is the port where the current leader replica is listening. Examples: ./build/app_server 3333 // start leader TCP server at port 3333 ./build/app_server 4545 3333 // start leader TCP server at port 4545 and connects to the leader at port 3333

Persistence

In case you want to access the persistence file, you can open the file named Users.db.