JSON Database (Java)

A minimal client–server key–value store that saves data as JSON.
It supports nested keys (JSON path as an array) and arbitrary JSON values (objects, arrays, numbers, booleans, null, strings).
The server is concurrent, safely handles multiple clients, and persists data to disk.

Features

• JSON over TCP: client sends one JSON request per connection; server replies with one JSON response and closes the socket.
• Operations:
  • get — read by key or path
  • set — create/update value at key/path
  • delete — remove key/path
  • exit — stop the server
• JCommander — parse -t/-k/-v and -in <file> modes
• Nested keys: key can be a string ("name") or an array ["person","surname"].
• Any JSON value: store objects, arrays, numbers, booleans, null, or strings.
• Persistence: data is stored at src/server/data/db.json.
• Concurrency: multiple clients; get is concurrent, set/delete are serialized via a ReadWriteLock.
• Predictable logs (for tests/CI):
  • Server: Server started!
  • Client: Client started!, Sent: ..., Received: ...

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Arguments

The arguments will be passed to the client in the following format:

java Main -t <type> -k <key> [-v <value>]

• -t specifies the type of request (get, set, or delete).
• -k specifies the key.
• -v specifies the value (only needed for set requests).
• -in specifies the file name at /client/data directory which contains request

For example:

• java Main -t set -k "text" -v "Here is some text to store on the server"
• java Main -in "userRequest.json"

Preview