CoralDB

An extremely simple in-memory key-value database for distributed applications and microservices, CoralDB has been designed with simplicity in mind. It works as a remote dictionary that can perform search, insertion, deletion and retrieval of string-string key-value pairs. Being an in-memory system, operations are handled extremely fast. For long term storage, cyclical checkpoint saves are executed.

Building and installation

• To build CoralDB, clone this repository and run make in it. C++11 is required.
• To install CoralDB, run make install.
• To uninstall CoralDB, simply run make uninstall. You will also manually have to delete any checkpoint files you may have created while using CoralDB.

Usage

CoralDB can be used both as a local or a remote database. In both cases, running coraldb starts the CoralDB server on the default CoralDB port (26725) using the file coraldb.db on your home directory as its checkpoint file. Check coraldb --help for information on how to launch CoralDB with a custom configuration.

Programs can connect to CoralDB to access the database system using its port and IP address (localhost for local systems). To communicate with CoralDB, 6 commands can be used, sent via a normal TCP socket stream. Sent messages must be terminated using the \r\n character sequence. Also, messages may not contain the \r\n character sequence, even within quotes. Messages sent by CoralDB always end with said character sequence, too.

A client must establish a new connection to CoralDB every time it wants to store a different value. Likewise, CoralDB closes the connection after a response has been sent to the client.

Command Index

Command	Description
SET	Inserts or updates a value into the database.
GET	Fetches a value from the database.
PROBE	Checks if a key exists the database.
DROP	Removes a key-value pair from the database.
PING	Checks if the database is online.
CHECKPOINT	Forces a database checkpoint save.
SETKEY	Sets the database password.
DELKEY	Removes the database password.
KEY	Authenticates with the database password.

SET

Usage: SET key "value"

SET stores "value" in key. Keys may not have whitespace in them. Values must be enclosed in double-quotes ("). Double-quotes inside a value may be escaped using the \" character sequence.

• Responses:
  • OK. for successful operations.
  • ERROR. for unsuccessful operations.

GET

Usage: GET key

GET gets the value stored in the key key. If no value had been assigned to said key, the operation fails.

• Responses:
  • "value" for successful operations, where value is the value retrieved. Note that the value is enclosed in double-quotes.
  • ERROR. for unsuccessful operations.

PROBE

Usage: PROBE key

PROBE succeeds if the key exists within the database, otherwise it fails.

• Responses:
  • FOUND. for successful operations.
  • NOT-FOUND. for unsuccessful operations.

DROP

Usage: DROP key

DROP deletes the key key from the database. The operation succeeds even if the key didn't previously exist.

• Responses:
  • OK. for successful operations.
  • ERROR. for unsuccessful operations.

PING

Usage: PING

PING can be used to check if CoralDB is alive.

• Responses:
  • OK. for successful operations.

CHECKPOINT

Usage: CHECKPOINT

CHECKPOINT can be used to trigger a checkpoint save.

• Responses:
  • OK. once the checkpoint save has finished.

SETKEY

Usage: SETKEY password

SETKEY can be used to protect the database behind a password. Once a password is set, unauthenticated commands will be rejected with the WRONG-KEY. error message after a random number of seconds.

• Responses:
  • OK. once the password has been set.

DELKEY

Usage: DELKEY

SETKEY can be used to remove the database password.

• Responses:
  • OK. once the password has removed.

KEY

Usage: KEY password <command>

KEY can be used to authenticate your request with a password. It's mandatory for databases that have previously set a password. To use the KEY command, prepend it to another command. For example, if you want to run GET mydata on a database protected behind the 123456 password, run KEY 123456 GET mydata.

Example Session

In this example, \r\n at the end of lines are omitted.

Client:  SET color1 "blue"
CoralDB: OK.
Client:  SET color2 "red"
CoralDB: OK.
Client:  SET color1 "other red, better than blue"
CoralDB: OK.
Client:  GET color2
CoralDB: "red"
Client:  DROP color2
CoralDB: OK.
Client:  GET color2
CoralDB: ERROR.

CoralDB Libraries

While coding your own CoralDB connector is a really easy task (that's what CoralDB was designed for), a number of CoralDB libraries for your favourite programming languages may exist. They can be found in the Libraries directory of this repository. If you write your own, please let me know so I can add it here!

I need help! I want to contribute!

If you need help on using CoralDB, please open an issue here and I will try to address it as soon as possible.

Contributions are also more than welcome! Feel free to submit pull requests!

License

CoralDB is released under the BSD 2-Clause License.