Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

https://github.com/daviddenton/fintrospect

Implement fast, type-safe HTTP webservices for Finagle
https://github.com/daviddenton/fintrospect

finagle framework http microservice performance scala techempower

Last synced: about 2 months ago
JSON representation

Implement fast, type-safe HTTP webservices for Finagle

Lists

README 

        


Fintrospect   

   

   

   

   

   




Fintrospect is a Scala web-framework with an intelligent HTTP routing layer, based on the 

Finagle RPC framework from Twitter. Via a shared contract, it provides a simple way to 

implement fast webservice endpoints and HTTP clients which are:



- ```Type-safe``` : auto-marshals request parameters/bodies into the correct primitive and custom types.

- ```Auto-validating``` : enforce the correctness of required/optional request parameters/bodies, generating a BadRequest if the contract is broken.

- ```Auto-documenting``` : runtime generation of endpoint documentation such as Swagger JSON or web sitemap XML. 

Generates JSON Schema for example object formats to be included in these API docs.

- ```Uniform``` : reuse the same contract to define both server endpoints and HTTP clients This also allows extremely low effort fake servers to be created



Additionally, Fintrospect provides a number of mechanisms to leverage these routes:



- Easily build type-safe HTTP responses with a set of custom builders for a wide variety of message formats:

  - JSON: Argo, Argonaut, 

  Circe, GSON, 

  Jackson, Json4S, Play JSON, 

  Spray JSON

    - Auto-marshaling of case classes instances to/from JSON (for `Argonaut`/`Circe`/`Json4S`/`Play`).

    - Implement simple `PATCH`/`PUT` endpoints of case class instances (`Circe` only).

  - Native implementations of XML, Plain Text, HTML, XHTML

  - MsgPack binary format

- Serve static content from the classpath or a directory

- Template ```View``` support (with Hot-Reloading) for building responses with Mustache or Handlebars

- Anonymising headers for dynamic-path based endpoints, removing all dynamic path elements. This allows, for example, calls to particular endpoints to be grouped for metric purposes. e.g. 

```/search/author/rowling``` becomes ```/search/author/{name}```

- Interacts seamlessly with other Finagle based libraries, such as Finagle OAuth2 

- Utilities to help you unit-test endpoint services and write HTTP contract tests for remote dependencies 



## Get it

Fintrospect is intentionally dependency-lite by design - other than Finagle, the core library itself only has a single non `org.scala` dependency. 

No dependency on `Scalaz`, `Cats` or `Shapeless`, so there are no compatibility headaches.



To activate the extension library features (JSON, templates etc), additional dependencies are required - please see here for details.



Add the following lines to ```build.sbt``` - the lib is hosted in Maven Central and JCenter:

```scala

resolvers += "JCenter" at "https://jcenter.bintray.com"

libraryDependencies += "io.fintrospect" %% "fintrospect-core" % "17.0.0"

```



## See the code

See the 

examples or 

cookbook in this repo, or clone the 

full example application repo.



## Learn it

See the full user guide here, or read on for the tldr; example. :)



### Server-side contracts

Adding Fintrospect routes to a Finagle HTTP server is simple. For this example, we'll imagine a Library application (see the example 

above for the full code) which will be rendering Swagger v2 documentation.



#### Define the endpoint

This example is quite contrived (and almost all the code is optional) but shows the kind of thing that can be done. Note the use of the 

example response object, which will be broken down to provide the JSON model for the Swagger documentation. 



```scala

// Response building methods and implicit conversion from ResponseBuilder -> Future[Response] pulled in here

import io.fintrospect.formats.Argo.ResponseBuilder._

import io.fintrospect.formats.Argo.JsonFormat.array



class BookSearch(books: Books) {

  private val maxPages = Query.optional.int("maxPages", "max number of pages in book")

  private val minPages = FormField.optional.int("minPages", "min number of pages in book")

  private val titleTerm = FormField.required.string("term", "the part of the title to look for")

  private val form = Body.form(minPages, titleTerm)



  private def search() = Service.mk[Request, Response] { 

    request => {

      val requestForm = form <-- request

      Ok(array(

        books.search(

            (minPages <-- requestForm).getOrElse(MIN_VALUE), 

            (maxPages <-- request).getOrElse(MAX_VALUE),

            titleTerm <-- requestForm

        ).map(_.toJson)))

    }

  }



  val route = RouteSpec("search for books")

    .taking(maxPages)

    .body(form)

    .returning(Status.Ok -> "we found your book", array(Book("a book", "authorName", 99).toJson))

    .returning(Status.BadRequest -> "invalid request")

    .producing(ContentTypes.APPLICATION_JSON)

    .at(Method.Post) / "search" bindTo search

}

```



#### Define a module to live at ```http://{host}:8080/library```

This module will have a single endpoint ```search```:



```scala

val apiInfo = ApiInfo("Library Example", "1.0", Option("Simple description"))

val renderer = Swagger2dot0Json(apiInfo) 

val libraryModule = RouteModule(Root / "library", renderer)

    .withRoute(new BookSearch(new BookRepo()).route)

Http.serve(":8080", new HttpFilter(Cors.UnsafePermissivePolicy).andThen(libraryModule.toService)) 

```



#### View the generated documentation

The auto-generated documentation lives at the root of the module, so point the Swagger UI at ```http://{host}:8080/library``` to see it.



### Client-side contracts

Declare the fields to be sent to the client service and then bind them to a remote service. This produces a simple function, which can 

then be called with the bindings for each parameter.



Since we can re-use the routes between client and server, we can easily create fake implementations of remote systems without having to 

redefine the contract. This means that marshalling of objects and values into/out of the HTTP messages can be reused.

```scala

  val theDate = Path.localDate("date")

  val gender = FormField.optional.string("gender")

  val body = Body.form(gender)



  val sharedRouteSpec = RouteSpec()

    .body(body)

    .at(Get) / "firstSection" / theDate



  val fakeServerRoute = sharedRouteSpec bindTo (dateFromPath => Service.mk[Request, Response] {

    request: Request => {

      // insert stub server implementation in here

      println("Form sent was " + (body <-- request))

      Ok(dateFromPath.toString)

    }

  })



  Await.result(new TestHttpServer(10000, fakeServerRoute).start())



  val client = sharedRouteSpec bindToClient Http.newService("localhost:10000")



  val theCall = client(

    body --> Form(gender --> "male"), 

    theDate --> LocalDate.of(2015, 1, 1)

  )



  println(Await.result(theCall))

```



## Upgrading?

See the changelog.



## Contributing

There are many ways in which you can contribute to the development of the library:



- Give us a ⭐️ on Github - you know you want to ;)

- Questions can be directed towards the Gitter channel, or on Twitter @fintrospectdev

- For issues, please describe giving as much detail as you can - including version and steps to recreate



See the contributor guide for details.