Test task (distributed map)

Distributed storage of map objects

How it works

System has three components:

• master server (manages clients and workers, process commands of distributed map)
• worker (single part of distributed map - stores map entries)
• client (console application - allows to send commands to server)

Commands from clients are sent to the server. Server process commands to store data into and get data from distributed map.

• put key:value (puts entry into distributed map (key - integer, value - string))
• get key (gets value by thie given key from distributed map)
• quit (disconnects client form server)
• shutdown (shutdowns server)

Usage

preconditions:

• docker must be installed

usage:

• build application by running of build.sh
• start master server (run-server.sh) with the given number of workers (by default - 2 workers)
• start clients (run-clients.sh) and send commands to the server

logging:

• system logs to /tmp/distributed_map.log

Consistency guaranties

• all data stored in memeory and workers can be added/removed manually, so
  • if we stop the server, all data will be lost
  • if we manually stop some worker, all data stored in this worker will be lost
  • if we manually start new worker after server is started and some data is stored in distributed map, part of stored data will not be available
• the system has not been tested under high load

Used documentation

• Netty in Action by Norman Maurer, Marvin Allen Wolfthal
• https://netty.io/
• https://docs.docker.com/

Tools and third-party libraries

• Intellij Idea
• Maven
• Netty
• Spring boot
• Logback

How long it takes

~40 hours

Known issues

• use-case "shutdown" doesn't not work correctly (client nodes don't stop)