hochgi/HTTP-stream-exercise

simple exercise with akka-streams & akka-http

akka-http server with bundled json events generator

Building

clone, cd and:

$ sbt stage

Above will generate following files:

.
└── target
    └── universal
        ├── scripts
        │   └── bin
        │       ├── http-stream-exercise
        │       └── http-stream-exercise.bat
        └── stage
            ├── bin
            │   ├── http-stream-exercise
            │   └── http-stream-exercise.bat
            ├── lib
            │   ├── com.hochgi.http-stream-exercise-0.0.1.jar
            │   └── …
            └── resources
                └── generator-linux-amd64

(you can also use dist instead of stage to get a packaged zip)

Running

Simply execute the script under generated bin dir:

$ bin/http-stream-exercise --help
  -m, --max-line-length  <arg>   Maximum length of lines coming out from
                                 generator (DEFAULT 8192)
  -p, --port  <arg>              Which port to use for the server (DEFAULT 1729)
  -h, --help                     Show help message

As seen in --help, you can pass some custom configs... Defaults should be good enough. default port should be quite unique, so you probably won't need to stop another server running on your machine just to test it.

Querying

Simple GET to localhost:$PORT/stats with optional ?pretty query parameter.

$ curl -s localhost:1729/stats
{"eventTypesCount":{"baz":3,"foo":4,"bar":6},"wordsCount":{"sit":1,"ipsum":3,"lorem":5,"amet":1,"dolor":3},"failCount":6}

or

$ curl -s localhost:1729/stats?pretty
{
  "eventTypesCount": {
    "baz": 5,
    "foo": 6,
    "bar": 10
  },
  "wordsCount": {
    "sit": 4,
    "ipsum": 3,
    "lorem": 6,
    "amet": 1,
    "dolor": 7
  },
  "failCount": 8
}

Possible improvements

• I usually add tests, and think every meaningful project should have tests. Future changes may break functionality unintentionaly, and good tests can save a lot of debugging time in the future.
• In this toy example, there isn't much that can go wrong. But in general, I prefer to avoid mutable shared state. the @volatile private[this] var stats is an example of what I prefer to avoid in larger systems. A more complex but reliable solution, would be to use a publisher that listeners can hook up into, and get latest updates properly.
• I only exposed a single API, and a more extensive solution can have multiple views. We can also think of a usefull API to expose the stream of events as a chunked response, and not just the accumulated value. We can also extend this to fetch events from multiple sources, and aggregate the stats.