ovo

OVO is an In-Memory Distributed Cache and a Key/Value Storage.

Main features

OVO is a distributed in-memory cache that supports data sharding on multiple instances and data replication. OVO offers these features:

• Multi-Master cluster architecture
• The nodes can be added and removed without stopping the cluster
• Data are replicated on many nodes if the cluster is configured for replication (Twin nodes)
• Keys are strings but every kind of data values can be stored (JSON documents, XML, images, byte arrays, ...)
• Auto-expiration, data will be automatically removed from the storage if the TTL of the object is setted
• Atomic counters
• OVO supports data sharding on many cluster nodes using smart clients

The project is under development.

Building OVO

Latest Build

Build Commands

$ go get github.com/maxzerbini/ovo
$ go build -i github.com/maxzerbini/ovo

Starting OVO

Start a single node

$ ovo

Start a three node cluster

$ ovo -conf=./conf/serverconf.json

$ ovo -conf=./conf/serverconf2.json

$ ovo -conf=./conf/serverconf3.json

Node configuration

The configuration file

The configuration file serverconf.json is a JSON file that defines the addresses and ports used by OVO to listen for HTTP calls and cluster communications. The configuration file defines also other configurations parameters used by the server node. These are the all the configuration parameters:

• Name is the unique node name, if omitted the node will generate a random one
• Host is the hostname or IP address of the HTTP listener, if it's omitted the server binds all the interfaces
• Port is the port of the HTTP listener
• APIHost is the hostname or IP address used for inter-cluster communications, if it's omitted the server binds all the interfaces
• APIPort is the port used for inter-cluster communications
• Twins is a list of node names of the cluster, the twins are the nodes used by the server to replicate its data
• Stepbrothers is a list of node names of the cluster, stepbrothers are the nodes to which the server requests to become a replica
• Debug is a flag that enables internal logging

This is a configuration file example

{
	"ServerNode":
	{
		"Node":
		{
			"Name":"mizard",
			"Host":"192.168.1.102",
			"Port":5050,
			"APIHost":"192.168.1.102",
			"APIPort":5052
		},
		"Twins":[],
		"Stepbrothers":[]
	},
	"Debug":true
}

Cluster configuration

OVO cluster can be formed by two or more nodes. Nodes can be added or removed without stopping the cluster activities. We must configure the node that is added to a cluster so that I can see at least another active node. This is done by providing a description (maybe partial) of the topology. This sample configuration allows us to create a cluster formed by two nodes mizard and righel and in which one is the twin of the other. The node mizard uses the above configuration, while the node righel uses the following configuration.

{
  "ServerNode": {
    "Node": {
      "Name": "righel",
      "Host": "192.168.1.103",
      "Port": 5050,
      "APIHost": "192.168.1.103",
      "APIPort": 5052
    },
    "Twins": ["mizard"],
    "Stepbrothers": ["mizard"]
  },
  "Topology": {
    "Nodes": [
      {
        "Node": {
          "Name": "mizard",
          "Host": "192.168.1.102",
          "Port": 5050,
          "APIHost": "192.168.1.102",
          "APIPort": 5052
        }
      }
    ]
  },
  "Debug": true
}

The temporary configuration file

Every time that the server starts or every time that the cluster topology changes the temporary configuration file is updated and saved. The temporary configuration file resides in the same folder of the configuration file and has the same name but its extension is .temp .

RESTful API

Clients can connect OVO using RESTful API.

The available API set includes these endpoints:

• GET /ovo/keystorage gives the count of all the stored keys
• GET /ovo/keys gives the list of all the stored keys
• GET /ovo/keystorage/:key retrieves the object corresponding to key
• POST /ovo/keystorage puts the body object in the storage
• PUT /ovo/keystorage same as POST
• DELETE /ovo/keystorage/:key removes the object from the storage
• GET /ovo/keystorage/:key/getandremove gets the object and removes it from the storage
• POST /ovo/keystorage/:key/updatevalueifequal updates the object with a new value if the input old value is equal to the stored object value
• POST /ovo/keystorage/:key/updatekeyvalueifequal updates the object end the key with a new values if the input old value is equal to the stored object value
• POST /ovo/keystorage/:key/updatekey changes the key of an object
• GET /ovo/cluster gets the cluster topology
• GET /ovo/cluster/me gets the node details
• POST /ovo/counters sets the value of the counter
• PUT /ovo/counters increments (or decrements) the value of the counter
• GET /ovo/counters/:key gets the value of the counter
• DELETE /ovo/counters/:key delete the counter
• POST /ovo/keystorage/:key/deletevalueifequal delete the object if it's not changed

Client libraries

Go client library

The Go OVO Client can connect a cluster of OVO nodes. The Go client source code can be found here ovoclient.

.Net client library

The .Net OVO Client can connect a cluster of OVO nodes and offers the same API of the Go client. The .Net client source code can be found here ovodotnet. The library can be downloaded from Nuget.org at https://www.nuget.org/packages/OVOdotNetClient/ or using the Nuget Package Manager.

PM> Install-Package OVOdotNetClient

Java client library

The Java client library is under development. The source code is in ovojava.