Packages

•  package root

  Definition Classes

  root

•  package com

  Definition Classes

  root

•  package twitter

  Start with com.twitter.finagle.

  Start with com.twitter.finagle.

  Definition Classes

  com

•  package finagle

  Finagle is an extensible RPC system.

  Finagle is an extensible RPC system.

  Services are represented by class com.twitter.finagle.Service. Clients make use of com.twitter.finagle.Service objects while servers implement them.

  Finagle contains a number of protocol implementations; each of these implement Client and/or com.twitter.finagle.Server. For example, Finagle's HTTP implementation, com.twitter.finagle.Http (in package finagle-http), exposes both.

  Thus a simple HTTP server is built like this:

  import com.twitter.finagle.{Http, Service}
  import com.twitter.finagle.http.{Request, Response}
  import com.twitter.util.{Await, Future}
  
  val service = new Service[Request, Response] {
    def apply(req: Request): Future[Response] =
      Future.value(Response())
  }
  val server = Http.server.serve(":8080", service)
  Await.ready(server)

  We first define a service to which requests are dispatched. In this case, the service returns immediately with a HTTP 200 OK response, and with no content.

  This service is then served via the Http protocol on TCP port 8080. Finally we wait for the server to stop serving.

  We can now query our web server:

  % curl -D - localhost:8080
  HTTP/1.1 200 OK

  Building an HTTP client is also simple. (Note that type annotations are added for illustration.)

  import com.twitter.finagle.{Http, Service}
  import com.twitter.finagle.http.{Request, Response}
  import com.twitter.util.{Future, Return, Throw}
  
  val client: Service[Request, Response] = Http.client.newService("localhost:8080")
  val f: Future[Response] = client(Request()).respond {
    case Return(rep) =>
      printf("Got HTTP response %s\n", rep)
    case Throw(exc) =>
      printf("Got error %s\n", exc)
  }

  Http.client.newService("localhost:8080") constructs a new com.twitter.finagle.Service instance connected to localhost TCP port 8080. We then issue a HTTP/1.1 GET request to URI "/". The service returns a com.twitter.util.Future representing the result of the operation. We listen to this future, printing an appropriate message when the response arrives.

  The Finagle homepage contains useful documentation and resources for using Finagle.

  Definition Classes

  twitter

•  object Thrift extends Client[ThriftClientRequest, Array[Byte]] with Server[Array[Byte], Array[Byte]]

  Client and server for Apache Thrift.

  Client and server for Apache Thrift. Thrift implements Thrift framed transport and binary protocol by default, though custom protocol factories (i.e. wire encoding) may be injected with withProtocolFactory. The client, Client[ThriftClientRequest, Array[Byte]] provides direct access to the thrift transport, but we recommend using code generation through either Scrooge or a fork of the Apache generator. A rich API is provided to support interfaces generated with either of these code generators.

  The client and server uses the standard thrift protocols, with support for both framed and buffered transports. Finagle attempts to upgrade the protocol in order to ship an extra envelope carrying additional request metadata, containing, among other things, request IDs for Finagle's RPC tracing facilities.

  The negotiation is simple: on connection establishment, an improbably-named method is dispatched on the server. If that method isn't found, we are dealing with a legacy thrift server, and the standard protocol is used. If the remote server is also a finagle server (or any other supporting this extension), we reply to the request, and every subsequent request is dispatched with an envelope carrying trace metadata. The envelope itself is also a Thrift struct described here.

  Clients

  Clients can be created directly from an interface generated from a Thrift IDL:

  For example, this IDL:

  service TestService {
    string query(1: string x)
  }

  compiled with Scrooge, generates the interface TestService.MethodPerEndpoint. This is then passed into Thrift.Client.build:

  Thrift.client.build[TestService.MethodPerEndpoint](
    addr, classOf[TestService.MethodPerEndpoint])

  However note that the Scala compiler can insert the latter Class for us, for which another variant of build is provided:

  Thrift.client.build[TestService.MethodPerEndpoint](addr)

  In Java, we need to provide the class object:

  TestService.MethodPerEndpoint client =
    Thrift.client.build(addr, TestService.MethodPerEndpoint.class);

  The client uses the standard thrift protocols, with support for both framed and buffered transports. Finagle attempts to upgrade the protocol in order to ship an extra envelope carrying trace IDs and client IDs associated with the request. These are used by Finagle's tracing facilities and may be collected via aggregators like Zipkin.

  The negotiation is simple: on connection establishment, an improbably-named method is dispatched on the server. If that method isn't found, we are dealing with a legacy thrift server, and the standard protocol is used. If the remote server is also a finagle server (or any other supporting this extension), we reply to the request, and every subsequent request is dispatched with an envelope carrying trace metadata. The envelope itself is also a Thrift struct described here.

  Servers

  TestService.MethodPerEndpoint must be implemented and passed into serveIface:

  // An echo service
  ThriftMux.server.serveIface(":*", new TestService.MethodPerEndpoint {
    def query(x: String): Future[String] = Future.value(x)
  })

  Definition Classes

  finagle

•  object param

  Definition Classes

  Thrift

• AttemptTTwitterUpgrade
• ClientId
• Framed
• MaxReusableBufferSize
• PerEndpointStats
• ProtocolFactory
• ServiceClass
• TReusableBufferFactory

com.twitter.finagle.Thrift.param

PerEndpointStats

Companion object PerEndpointStats