[api] Design the REST API

[ndragazis]

Copying API requirements from #1:

• Insert / update key-value
• Query a key
• Query sorted list of keys
• Delete a key

Other kv stores to consult:

• etcd
• https://github.com/google/leveldb
• https://github.com/facebook/rocksdb
• https://github.com/geohot/minikeyvalue

[ndragazis]

Etcd REST API

Etcd is a key-value store that used to have a REST API in v2. Let's explore its API. doc: https://etcd.io/docs/v2.3/api/

---

Insert / update of a single key/value pair:

• request: PUT v2/keys/<key>
• payload: value="Hello world"
• response: ...

Query of a single key, returning its value:

• request: GET v2/keys/<key>
• response:

    {
      "action": "get",
      "node": {
          "createdIndex": 2,
          "key": "/message",
          "modifiedIndex": 2,
          "value": "Hello world"
      }
  }

Delete a single key (and its associated value):

• request: DELETE v2/keys/<key>
• response: ...

List all keys under a directory:

• request: GET v2/keys/
• optional query parameter: recursive=true

[ndragazis]

If we pass keys as path-based parameters like etcd, we need to consider URL size limitations.

Browsers typically support URLs with up to 2048 characters. Also URLs support only ASCII characters, so if keys have a UTF-8 encoding, they have to be URL-encoded, which would consume more bytes.

All things considered, we are probably safe with a 255-byte limit on the keys.