Meetup in Tokyo #28 - JVM非同期プログラミング - https://line.connpass.com/event/78912/ の登壇資料です

1. 이희승 (@trustin) ／ 開発1センター ／ LINE
Building Asynchronous
Microservices with Armeria
Armeriaで始める非同期Microservice開発

2. Why build another
microservice framework?

3. Asynchrony
●
Most web frameworks are blocking and synchronous.
– 1000 concurrent requests require 1000 threads.
– In modern systems, a service sends requests to another backend.
– Threads are busy doing nothing but just waiting for the backend.
– Request queue is not consumed fast enough.
– Result:
●
Fragile system that falls apart even on a tiny backend failure
●
Inefficient system that takes more memory and CPU than what it actually does

4. Reactive Streams
●
Should we really buffer everything until a response is sent?
– Retrieving 100,000 rows from a table
●
Why should a client send many requests to reduce the server memory
pressure?
– Retrieving 1,000 rows 100 times
●
What if we want to stream infinitely?
– Stock quotes
●
Our protocol is not a problem here.
– Our ‘blocking’ programming model is blocking ‘us’.

5. Better RPC support
●
RPC has been hardly a 1st-class citizen in web
frameworks.
– Distinction from RPC-level and HTTP-level failure
– Access logs with RPC-level details
– Debugging console
●
What if …
– We build a microservice framework with RPC at its core?

6. More reasons back in 2015
●
Leverage Java 8 syntax
– Lambda expressions
– Default interface methods
– Static interface methods
●
Provide ‘working’ HTTP/2 implementation
– ‘H2C’ support (HTTP/2 over ‘C’leartext)
– OpenSSL-based faster TLS connection

7. Better UX for devs
●
This is the last yet most important part.
●
Nobody wants a framework that’s hard to use.
●
Can we design …
– a user-friendly asynchronous programming API
– … with modest learning curve?

8. Our answer – Armeria
●
HTTP/2
– Both ciphertext and cleartext, a.k.a. h2 and h2c
●
Reactive
– Implements Reactive Streams API
●
Ability to mix different types of services in a single server
– gRPC, Thrift, REST services
– Legacy webapps via embedded Tomcat or Jetty
●
High-performance
– Netty with /dev/epoll transport and BoringSSL SSLEngine
●
Easy to learn and fun to use (hopefully)

9. Armeria by examples
HTTP / REST

10. Hello, world!

11. Hello, world – Parameterized

12. Hello, world – Annotated

13. With CompletableFuture

14. Streaming a million integers

16. There are more!
●
Query parameters
●
Request and response converters
●
Exception handlers
●
Content type negotiation
●
Regular-expression path mapping
●
Aims to be on-par or better than <your favorite web framework>

17. Armeria by examples
Thrift and gRPC

18. gRPC & Thrift basics
a. Write an IDL file – .proto or .thrift
b. A compiler compiles it into .java files.
c. Implement interfaces generated at ‘b’.

19. gRPC

20. Thrift

21. Decorating services
Separation of concerns

22. Intercepting an HTTP request

23. Intercepting a RPC request
●
Complete access to the RPC call information
●
Override the parameters and methods

24. Decorator as core extension mechanism
●
Request throttling
●
Metric collection
●
Distributed tracing (Zipkin)
●
HTTP content encoding
●
HTTP authn/z
●
CORS
●
Circuit breakers
●
Automatic retries
●
…

25. Distributed tracing with Brave·Zipkin

26. Playing better with RPC
Armeria documentation service

27. Armeria documentation service
●
Enabled by adding DocService to ServerBuilder
●
Browse and invoke RPC services in an Armeria server
●
Supports both gRPC and Thrift
●
We have a plan to add:
– Support for plain HTTP, like Swagger
– Metric monitoring console
– Runtime configuration editor, e.g. logger level

30. ●
Share the URL to reproduce a call.

31. All the pieces fit together
The ultimate all-in-one micro(?) service

33. What about client-side?

34. Armeria client API
●
Similar experience to the server-side API
– e.g. Common type, Decorators, RPC-friendliness
●
Client-specific stuff
– Circuit breakers
– Automatic retries
– Client-side load balancing
– Retrofit integration

36. Got interested?

37. Let’s build Armeria together!
●
Use it.
●
Ask questions.
●
Request new features.
●
Tell us what rocks and sucks.
●
Consider joining the effort.

38. Meet us at GitHub and Slack
●
https://github.com/line/armeria
●
https://line-slacknow.herokuapp.com/line-armeria/