Micro on NATS Microservices with messaging

Who am I? Asim Aslam Working on Micro Previously at Hailo Before then Google @chuhnk asimaslam.com

What is Micro? A microservice ecosystem Simplifying building and managing distributed systems What does that even mean? Building OSS tools that make it easier to write and run micro service applications Written in Go 100% Open Source

Micro A Microservice Toolkit Go Micro - Pluggable RPC framework for writing microservices API - API gateway. Translates HTTP to RPC. Path-to-Service resolution Web - Dashboard and reverse proxy. Web apps as first class citizens CLI - Command line interface. Straight forward. No frills. Sidecar - HTTP interface with all the features of Go Micro Bot - Hubot style bot for ChatOps. CLI Features. A bot? Really? Yea dude!

Go Micro RPC Framework Registry - Service Discovery Selector - Client side load balancer Transport - Synchronous Communication Broker - Asynchronous Communication Codec - Message encoding Client - RPC Client Server - RPC Server

Why NATS? Built for high performance and scale Highly available - client and server side clustering Extremely lightweight - written in Go, no persistence features At most once delivery - fire and forget Simple, focused and made for microservices Written by Derek Collison, with two decades of experience building messaging systems

Micro on NATS NATS Plugins Go-Micro has a pluggable architecture Each feature written as a Go interface. Just implement the interface. Integrate NATS using plugins for: Registry - Service Discovery Transport - Synchronous Communication Broker - Asynchronous Communication

Transport Synchronous Communication Handles request-response Supports bidirectional streaming Socket style semantics; Send(), Recv(), Close() type Transport interface { Dial(addr string, opts ...DialOption) (Client, error) Listen(addr string, opts ...ListenOption) (Listener, error) String() string }

Transport 1. Server Listen - Subscribes to unique topic, wait for pseudo connections 2. Client Dial - Subscribes to unique topic, publishes to Server with reply topic set 3. Server Socket - Pseudo Socket created for every new “connection” 4. Client Socket - Same as server. Send() - Publish, Recv() - Subscribed messages

Broker Asynchronous Communication Publish and Subscribe mechanism Includes notion of Topics and Channels (Queues) Distribute messages between subscribers type Broker interface { …. Connect() error Disconnect() error Publish(string, *Message, ...PublishOption) error Subscribe(string, Handler, ...SubscribeOption) (Subscriber, error) String() string }

Broker 1. Subscribe - Register interest to Topic. Specify Queue to distribute messages 2. Publish - Asynchronously publish to Topic 3. Encoding - Broker encodes Message to JSON

Registry Service Discovery Service discovery using a message bus? What magic is this? type Registry interface { Register(*Service, ...RegisterOption) error Deregister(*Service) error GetService(string) ([]*Service, error) ListServices() ([]*Service, error) Watch() (Watcher, error) String() string }

Broadcast Queries! 1. All services subscribe for queries on a broadcast topic 2. Publish query on broadcast topic with reply address 3. Instances of queried service respond 4. Wait for responses until upper time limit 5. Aggregate and return results

Scaling Like A Boss Cluster per AZ or Region Multi-AZ deployment Fault tolerant of AZ failure Pattern for high availability Multi-region deployment Use DNS latency based routing

Thanks for listening! Micro on NATS blog post blog.micro.mu/2016/04/11/micro-on-nats.html Micro on GitHub Follow on Twitter! github.com/micro @MicroHQ Micro on Web Join the Slack community! micro.mu slack.micro.mu