rust-microservice-example

Second evaluation of Rust web ecosystem - Simple Microservice with Hyper, Serde, Futures

Motivation

Since my last evaluation of the Rust web ecosystem in Summer 2017 and post Futures 0.2 release, this repository is another evaluation sample of the current state of the art. Basic requirements to write simple microservices:

• Low friction setup for a http server, with support for HTTP 1.1 & 2.0
• Easy setup routing with optional support for middleware
• Easy setup for execution contexts, e.g. easy switch between thread pools and single threaded execution
• Implementation with std-lang features of a domain's bounded context: Services, Repositories, Entities, Value Objects
• Straight forward serialization/deserialization for compound types w/o own impls for a wide range of std types.
• Fully support asynchronous I/O from Service down to repositories, client calls, heavy computations, aggregations, etc.

Evaluation results

• Setting up a http server with hyper is still a frictionful job, because determining the correct version is hard:
  • Current 0.11 release is lacking HTTP 2 and bases on Futures 0.1 which in turn is missing executors
  • Master is upcoming 0.12 which has support for HTTP 2, but still locked in Futures 0.1 because tokio is not upgraded to Futures 0.2, yet.
  • Support for middleware is still a manual job
  • Documentation and examples are work in progress for 0.12.
  • Implementation of an impl Service is not as easy as passing a function to fn service_fn
• Routing support is easy
• Switching between execution context is easy thanks to hyper::server::Http::executor
• Implementing simple services, repositories and wiring dependencies still a hurdle due to lifetimes, but managable. More help in the future with Rust 2018 for more lifetime ellision Issue 4493
• Serde is still rock solid and good companion.
• Full asynchronous I/O support is questionable, since other crates not rebased upon Futures 0.2, yet.
  • Async/Await is still available only in nightly.
  • Tokio is still not on Futures 0.2 and according to hyper's issue tracker will wait until 0.3 or merge into Std library.

Not evaluated

• Async/Futures support for typical storage connectors: MySQL, PostgreSQL, MongoDB, ElasticSearch
• Async/Futures support for typical serialization protocols: Protobuf, Thrift, Avro