Simple Key value Store

This project aims to be a simple and generic key-value store. It can be used as a Java library, or as a small, REST-based webservice. It supports in-memory storage, auditfiles and SQLite databases. It also features with caching when used with SQLite.

REST-based webservice

The REST-based webservice only supports plaintext, string data.

Starting

Command to start the application:

java -cp kvstore_0.7.jar kvstore.web.WebStore -dbFile [file] -serverHost [hostname] -serverPort [port] -backlog [value] -listenUrl [path]

Where the parameters are as follows:

• dbfile: the file that should be used by the key-value store. If it doesn't exists, it will be created.
• serverHost: the hostname or IP of the server to be created.
• serverPort: the listener port of the server.
• backlog: [optional]: this is the backlog value as documented for the Java HttpServer class.
• listenUrl: the URL part for which the server should listen.

For example:

java -cp kvstore_0.7.jar kvstore.web.WebStore -dbFile /home/user/dbfile.db -serverHost 127.0.0.1 -serverPort 8081 -listenUrl /store

will end up with a service on http://127.0.0.1:8081/store URL. The logs will be written to the console.

Usage

The server supports four main HTTP methods: GET, POST, PUT, DELETE. The HTTP return codes corresponds to the state of the processing of the request. The provided test.sh can be used to test the newly started instance. Example usages follow:

# Create new value myKey=myData.
curl -X POST 'myData' http://localhost:8081/store/myKey

# Read the newly created data.
curl http://locahost:8081/store/myKey

# Update the newly created data to myData2.
curl -X PUT 'myData2' http://locahost:8081/store/myKey

# Delete it.
curl -X DELETE http://localhost:8081/store/myKey

Every data is returned and expected to be received with the content type of text/plain. Listing every data or wildcarding is not currently supported.

Usasge as an API

There are two main parts of the key-value store, the Store itself, which expects a Persister instance upon creating the object. The key-value store itself is a generic object, which accepts both as key and value a serializable type, which is then converted to Base64.

Persisters

The currently available persisters are:

• Audit
• Empty
• SQLite

The Audit persister creates an audit file with one of the following operations:

• ADD
• REMOVE

The Empty persister is basically a 'null object', which can be used to start the key-value store in the in-memory mode. It doesn't perform any real persisting operation.

The SQLite persister is used to create a small, one file database to be used to store the data added. By default, it caches the keys to speed up some operations. It also returns a lazy hash map, which feches data only when it is accessed thus eliminating the need of storing the entire database in the memory.