Hati

v0.3.0-dev

IN DEVELOPMENT. DO NOT USE IN PRODUCTION.

Hati is a simple distributed (in-memory and persistent) key/value store and a message broker.

Hati is meant to work in trusted networks - where all nodes operators know each other and can be trusted.

Once connected as a client to Hati server you can publish commands which will be processed by the server and published over the Hati network - Hati nodes can be connected to each other creating network of nodes but it is prefectly fine to run Hati as a single instance.

Current version

[req] [req]  
  ^     ^
  v     v
[Hong Kong]

v2.0.0

[req][req] [req][req] [req][req]
    ^          ^           ^
    v          v           v
[London]  [Hong Kong] [New York]
    ^          ^          ^
    |----------|----------|

Current features

• TCP server
• JSON-RPC server
• Storing data in in-memory storage type - with sharding
• Storing data in hdd

Configuration

While starting Hati hati start there are configurational flags available to be set.

• --tcp - indicates if should start TCP server, by default it is off
• --tcp-host - determines bind host for TCP server, default value is 0.0.0.0
• --tcp-port - bind port for TCP server, default value is 4242
• --rpc - indicates if should start JSON-RPC server, by default it is off
• --rpc-host - bind host for JSON-RPC server, default 0.0.0.0
• --rpc-port - bind port for JSON-RPC server, default 6767
• --data-dir - absolute path to directory where Hati can store files, default /current/path/to-hati/data
• --cpu-num - number of CPU cores which should be used by Hati, by default it will set for as many as available

Protocol Commands

Key-Value Storage

SET <type> <ttl> <key> <value>\n - save key with provided value to the selected storage type.

Hati offers two storage types: memory and hdd . By default <ttl> is set to zero 0 which means that value will be stored on the hard-drive. Ttl value is in ms, if higher than 0 Hati can guarantee that value will be stored at minimum for provided ttl value and will be removed from the storage shortly (as soon as possible) after that.

HAS <type> <key>\n - check if provided key exist in given storage type

GET <type> <key>\n - get value for provided key in given storage type

DELETE <type> <key>\n - get value for provided key in given storage type

FLUSHALL <type>\n - flush (delete) all data from given storage type

JSON-RPC Methods

Storage

• Storage.Set - set key and value
  • type - storage type: memory / hdd
  • key
  • value
  • ttl
• Storage.Has - check if provided key exist
  • type - storage type: memory / hdd
  • key
• Storage.Get - get key
  • type - storage type: memory / hdd
  • key
• Storage.Delete - delete key
  • type - storage type: memory / hdd
  • key
• Storage.FlushAll - deletes all keys
  • type - storage type: memory / hdd
• Storage.Count - returns number of keys
  • type - storage type: memory / hdd

Message broker

• Broker.

To do

Below you can find list of features planned to be released in upcoming versions. Please keep in mind that non of these list is a set stone and items can be added/removed but it gives overall image of what are the plans for the near future.

v1.0.0

• Configuration options via CLI flags
• Memory and persistent (LevelDB) key-value storage
• TCP server
• JSON-RPC server
• TCP and JSON-RPC commands:
  • SET, GET, HAS, DELETE, FLUSHALL, COUNT
  • CREATEROUTER, CREATEQUEUE, PUBLISH, ACK, GETROUTER, GETQUEUE, LISTROUTER, LISTQUEUE, FLUSH
• TCP server cancel context for graceful shutdown
• RPC server cancel context for graceful shutdown
• Graceful shutdown of HDD storage
• Implement TTL
• CLI command to export/import backup of persistent storage
• Message broker
• Command to return server statistics
  • Number of keys for each storage type
  • Number of keys in each shard
  • Active TCP connections
  • Message broker statistics
• Communication via UNIX socket
• Access protected by credentials

v1.1.0

• Rebuilding persistent storage if number of shards has changed
• TLS support for TCP

v2.0.0

• Nodes clustering
• Data synchronization between nodes
  • TCP
  • P2P (? - TBD)