AVA

AVA is a framework for microservice development.

Overview

AVA provides the core requirements for distributed systems development including RPC and Event driven communication. The micro philosophy is sane defaults with a pluggable architecture. We provide defaults to get you started quickly but everything can be easily swapped out.

Features

AVA abstracts away the details of distributed systems. Here are the main features.

• Core - AVA Framework Core functionality provides the basis for developing and improving third-party integration. It offers the basic functionality that is needed to connect to a database system, blockchain, RESTful APIConfig, etc.

• Tools -

• Service Discovery - Automatic service registration and name resolution. Service discovery is at the core of micro service development. When service A needs to speak to service B it needs the location of that service. The default discovery mechanism is multicast DNS (mdns), a zeroconf system.

• Load Balancing - Client side load balancing built on service discovery. Once we have the addresses of any number of instances of a service we now need a way to decide which node to route to. We use random hashed load balancing to provide even distribution across the services and retry a different node if there's a problem.

• Message Encoding - Dynamic message encoding based on content-type. The client and server will use codecs along with content-type to seamlessly encode and decode Go types for you. Any variety of messages could be encoded and sent from different clients. The client and server handle this by default. This includes protobuf and json by default.

• Request/Response - RPC based request/response with support for bidirectional streaming. We provide an abstraction for synchronous communication. A request made to a service will be automatically resolved, load balanced, dialled and streamed. The default transport is gRPC.

• Async Messaging - PubSub is built in as a first class citizen for asynchronous communication and event driven architectures. Event notifications are a core pattern in micro service development. The default messaging system is an embedded NATS server.

Contents

Contents of this repository:

Directory	Description
Core	Logger, Configuration, Version, Time, Serializer, .....
Tools	avaEnum, avaWrapper
Broker	PubSub messaging; NATS, NSQ, RabbitMQ, Kafka
Client	RPC Clients; gRPC, HTTP
Codec	Message Encoding; BSON, Mercury
Registry	Service Discovery; Etcd, Gossip, NATS
Selector	Load balancing; Label, Cache, Static
Server	RPC Servers; gRPC, HTTP
Transport	Bidirectional Streaming; NATS, RabbitMQ
Wrapper	Middleware; Circuit Breakers, Rate Limiting, Tracing, Monitoring

Getting Started

See the docs for detailed information on the architecture, installation and use of AVA.