BMis

Version: v0.5.0

In-memory data platform.

BMis starts as a minimal key-value engine and is evolving toward a networked database with persistence, messaging, and distributed capabilities.

Current status

v0.5.0 — TypeScript interactive CLI plus a TCP server over a shared in-memory key-value store, with unit tests for the database, parser, command executer, RESP encoder, and TCP server. On start, BMis listens on 127.0.0.1:6379. Clients send one plain-text command per line; replies are RESP. The local CLI remains available. The database layer uses an injectable Storage backend (defaults to in-memory). Values are stored with type metadata — strings and lists are supported and can be inspected with TYPE. Integer strings can be incremented or decremented with INCR and DECR. Lists support LPUSH, RPUSH, LPOP, RPOP, LRANGE, LLEN, LINDEX, LSET, LTRIM, RPOPLPUSH, and LPOS. Keys can expire via EXPIRE, SET ... EX, or remaining TTL can be queried with TTL; expired keys are removed lazily on GET, TTL, and TYPE, and SET clears expiration when overwriting a key.

Command	Args	Description	Example
SET	key, value [EX seconds]	Store a key-value pair, optionally with expiration	SET session active EX 60 → OK
GET	key	Retrieve a value by key	GET name → Mayur (or null if missing or expired)
DEL	key [key ...]	Remove one or more keys	DEL name city → 2 (count of keys deleted)
EXISTS	key [key ...]	Count how many keys exist	EXISTS name missing → 1
EXPIRE	key, seconds	Set a key's time-to-live in seconds (0 expires immediately)	EXPIRE session 60 → 1 (or 0 if key missing)
TTL	key	Get remaining TTL in seconds	TTL session → 60 (or -1 / -2; see below)
TYPE	key	Get the type of a key	TYPE name → string (or list / none)
INCR	key	Increment an integer string value by 1	INCR counter → 11 (creates key as 1 if missing)
DECR	key	Decrement an integer string value by 1	DECR counter → 9 (creates key as -1 if missing)
LPUSH	key, value [value ...]	Prepend one or more values to a list	LPUSH fruits apple banana → 2
RPUSH	key, value [value ...]	Append one or more values to a list	RPUSH fruits apple banana → 2
LPOP	key	Remove and return the first list element	LPOP fruits → apple (or null if missing)
RPOP	key	Remove and return the last list element	RPOP fruits → orange (or null if missing)
LRANGE	key, start, stop	Return a range of list elements (inclusive)	LRANGE fruits 0 -1 → full list
LLEN	key	Get the length of a list	LLEN fruits → 3 (or 0 if missing)
LINDEX	key, index	Get a list element by index	LINDEX fruits 0 → apple (or null if out of range)
LSET	key, index, value	Set a list element at index	LSET fruits 1 mango → OK
LTRIM	key, start, stop	Trim a list to the given inclusive range	LTRIM fruits 1 2 → OK
RPOPLPUSH	source, destination	Pop the last element of source and prepend it to destination	RPOPLPUSH source dest → C (or null if source is missing)
LPOS	key, element [RANK rank] [COUNT count]	Return the index of an element, or a list of indexes when COUNT is set	LPOS users John → 1 (or null if missing)

Commands are case-insensitive. For SET, everything after the key is the value (spaces allowed), unless EX seconds is appended to set expiration in the same command.

Errors:

• Unknown command → ERR unknown command '<COMMAND>'
• Wrong arity → ERR wrong number of arguments for <COMMAND> command
• Invalid EXPIRE seconds (non-integer or out of range) → ERR value is not an integer or out of range
• Invalid INCR / DECR value (non-integer) → ERR value is not an integer or out of range
• Invalid SET ... EX syntax, or an unknown LPOS option → ERR syntax error
• Invalid SET ... EX seconds → ERR invalid expire time in 'SET' command
• Invalid LPOS rank (non-integer or 0) or non-integer COUNT → ERR value is not an integer or out of range
• Negative LPOS COUNT → ERR count should be > 0
• Wrong type for list operation → WRONGTYPE Operation against a key holding the wrong kind of value
• Missing list for LSET → ERR no such key
• Out-of-range index for LSET → ERR index out of range

Project structure

src/
├── index.ts                      # CLI + TCP server entry point
├── types.ts                      # Shared TypeScript types
├── server/
│   ├── tcp-server.ts             # TCP server (default 127.0.0.1:6379)
│   └── protocol.ts               # RESP encoder for TCP replies
├── database/
│   ├── database.ts               # Typed value store with injectable Storage backend
│   └── storage.ts                # Low-level Map-backed storage layer
└── commands/
    ├── command-executer.ts       # Routes parsed input to command handlers
    ├── parser.ts                 # Parses CLI input into command and args
    ├── commands.ts               # Command registry
    ├── set.ts                    # SET command
    ├── get.ts                    # GET command
    ├── del.ts                    # DEL command
    ├── exists.ts                 # EXISTS command
    ├── expire.ts                 # EXPIRE command
    ├── ttl.ts                    # TTL command
    ├── type.ts                   # TYPE command
    ├── incr.ts                   # INCR command
    ├── decr.ts                   # DECR command
    ├── lpush.ts                  # LPUSH command
    ├── rpush.ts                  # RPUSH command
    ├── lpop.ts                   # LPOP command
    ├── rpop.ts                   # RPOP command
    ├── lrange.ts                 # LRANGE command
    ├── llen.ts                   # LLEN command
    ├── lindex.ts                 # LINDEX command
    ├── lset.ts                   # LSET command
    ├── ltrim.ts                  # LTRIM command
    ├── rpoplpush.ts              # RPOPLPUSH command
    └── lpos.ts                   # LPOS command
tests/
├── database.test.ts              # Database unit tests (node:test)
├── commands.test.ts              # CommandExecuter / CLI command tests
├── parser.test.ts                # CLI input parser tests
└── server/
    ├── protocol.test.ts          # RESP encoder tests
    └── tcp-server.test.ts        # TCP server tests

Requirements

• Node.js (LTS recommended)
• TypeScript (installed via npm install; used as a dev dependency)

Tests use the built-in node:test runner against the compiled dist/ output.

Run

npm install
npm run build
npm start

npm start runs the compiled entry point (node dist/src/index.js). It starts the TCP server on 127.0.0.1:6379 and the interactive CLI. npm test builds first, then runs tests from dist/.

Test

npm test

For a full walkthrough of commands, TCP usage, responses, and errors, see USER_GUIDE.md.

Starts an interactive session (TCP is also listening):

BMIS TCP server listening on 127.0.0.1:6379
Welcome to BMis CLI
Type commands like: SET name Mayur
BMis> SET name Mayur
OK
BMis> GET name
Mayur
BMis> EXISTS name
1
BMis> DEL name
1
BMis> GET name
null
BMis> SET
ERR wrong number of arguments for SET command

Connect with a line-based client (for example nc 127.0.0.1 6379) and send the same commands, one per line. Replies use RESP (+OK, :n, bulk strings, arrays, $-1 for null, and - errors). Inbound RESP, such as from redis-cli, is not parsed yet.

Roadmap (high level)

Incremental versions toward:

• Multiple native data structures (strings and lists supported; hashes pending)
• Key expiration
• TCP networking and client-server communication (plain-text commands on 127.0.0.1:6379 in place)
• RESP-compatible protocol (reply encoding in place; command parsing still plain text)
• Persistence (injectable Storage layer in place)
• Pub/Sub
• Replication and distributed capabilities

See BMis Mission — Redis-Inspired In-Memory Data Platform.md for the full mission and design principles, and BMis — Docker Runtime Standard.md for the intended Docker-first runtime model.

License

ISC