Add example

examples/README.md

@@ -0,0 +1,50 @@
+# A Simple GRPC Client/Server in Haskell
+This directory contains a simple Client/Server example with a single RPC call.
+The Client calls the server with a list of numbers, and the server sums up these numbers and sends the answer back to the client.
+
+# The Protobuf Definition
+The protobuf definition is in a single file, *calcs.proto*.
+```
+syntax = "proto3";
+
+package calcs;
+
+service Arithmetic {
+  rpc Add(CalcNumbers) returns (CalcNumber) {}
+}
+
+message CalcNumbers {
+    repeated CalcNumber values = 1;
+  }
+
+message CalcNumber {
+  uint32 code = 1;
+}
+```
+
+Each RPC call takes a single message, and returns a single message.  In this case the request is a *CalcNumbers* and the response is a *CalcNumber*.  Protobuf allows message types to be nested.  In this case *CalcHumbers* is comprised of a list of *CalcNumber* values.  *CalcNumber* itself is a [32 bit unsigned int](https://developers.google.com/protocol-buffers/docs/proto3#scalar_value_types).
+
+# Getting it working
+The *calcs.proto* definition file is used to generate Haskell code via the *protoc* tool, which needs to be installed separately.  There are two Haskell files generated. The simplest way to build the client and server is to copy these generaeted source files to somewhere accessible within your stack package.
+
+## Starting the Server
+The server is in ArithServer.hs, and can be started from *ghci*.
+
+~~~
+stack ghci
+:l ArithServer
+someFunc' []
+~~~
+
+This starts the server on port 3000.
+
+## Starting the Client
+The client is ArithClient.hs and can be started as shown below:
+
+~~~
+stack ghci
+ArithClient.main
+~~~
+
+The client sends a single request to the server, processes the response and terminates.
+Both client and server output a few log lines to show what is happening.

examples/examples.cabal

@@ -1,10 +1,10 @@
 cabal-version: 1.12
 
--- This file has been generated from package.yaml by hpack version 0.31.2.
+-- This file has been generated from package.yaml by hpack version 0.33.0.
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 6b8490732f6b8b92312b3d51b0bbd4ccda7081b339c78f7346f5d017c7470535
+-- hash: 59e86b4638bab931cb9948900fd08b2b735376fb44120e9889d1af96262ce663
 
 name:           examples
 version:        0.4.0.1
@@ -28,7 +28,11 @@ source-repository head
 
 library
   exposed-modules:
+      ArithClient
+      ArithServer
       Example
+      Proto.Protos.Calcs
+      Proto.Protos.Calcs_Fields
       Proto.Protos.Grpcbin
       Proto.Protos.Grpcbin_Fields
   other-modules:
@@ -52,4 +56,7 @@ library
     , proto-lens
     , proto-lens-runtime
     , unliftio-core >=0.1 && <0.3
+    , warp
+    , warp-grpc
+    , warp-tls
   default-language: Haskell2010

examples/package.yaml

@@ -25,12 +25,15 @@ dependencies:
 - http2-grpc-types >= 0.5 && < 0.6
 - http-types >= 0.12 && < 0.13
 - unliftio-core >= 0.1 && < 0.3
+- microlens
 - proto-lens-runtime
 - proto-lens
 - http2-client-grpc
 - http2-grpc-proto-lens
 - http2-client
-- microlens
+- warp
+- warp-grpc
+- warp-tls
 
 library:
   source-dirs: src

examples/prepare_calcs.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+#mkdir -p gen
+#mkdir -p gen-bin
+#mkdir -p protos
+
+#curl 'https://raw.githubusercontent.com/moul/pb/master/grpcbin/grpcbin.proto' > protos/grpcbin.proto
+
+stack install --local-bin-path=gen-bin proto-lens-protoc
+
+protolens="`pwd`/gen-bin/proto-lens-protoc"
+
+if [ -x "${protolens}" ]
+then
+	echo "using ${protolens}" ;
+else
+	echo "no proto-lens-protoc"
+	exit 2
+fi;
+
+protoc  "--plugin=protoc-gen-haskell-protolens=${protolens}" \
+	--haskell-protolens_out=./gen \
+	./protos/calcs.proto
+
+echo "# Generated modules:"
+find gen -name "*.hs" | sed -e 's/gen\///' | sed -e 's/\.hs$//' | tr '/' '.'
+
+cp -r gen/* examples/src

examples/protos/calcs.proto

@@ -0,0 +1,16 @@
+syntax = "proto3";
+
+package calcs;
+
+service Arithmetic {
+  rpc Add(CalcNumbers) returns (CalcNumber) {}
+}
+
+message CalcNumbers {
+    repeated CalcNumber values = 1;
+  }
+
+message CalcNumber {
+  uint32 code = 1;
+}
+

examples/src/ArithClient.hs

@@ -0,0 +1,48 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module ArithClient where
+
+import Control.Monad (void)
+import Control.Monad.IO.Class (liftIO)
+import Proto.Protos.Calcs
+import Proto.Protos.Calcs_Fields 
+import Network.GRPC.Client
+import Network.HTTP2.Client
+import Network.GRPC.Client.Helpers
+import Network.GRPC.HTTP2.Encoding
+import Lens.Micro
+import Network.GRPC.HTTP2.ProtoLens
+
+import Data.ProtoLens
+
+-- create a simple CalcNumbers via lens operations for later use
+val1, val2, val3 :: CalcNumber
+val1 = defMessage & (code .~ 7)
+val2 = defMessage & (code .~ 77)
+val3 = defMessage & (code .~ 777)
+
+vals :: CalcNumbers
+vals = defMessage & (values .~ [val1, val2, val3])
+---
+
+main :: IO ()
+main = do
+  let encoding = Encoding uncompressed
+  let decoding = Decoding uncompressed
+  let host = "127.0.0.1"
+  let port = 3000
+  void $ runClientIO $ do
+    conn <- newHttp2FrameConnection host port (tlsSettings False host port)
+    liftIO $ print $ "connecting on port " ++ (show port)
+    runHttp2Client conn 8192 8192 [] defaultGoAwayHandler ignoreFallbackHandler $ \client -> do
+      liftIO $ putStrLn "~~~connected~~~"
+      let ifc = _incomingFlowControl client
+      let ofc = _outgoingFlowControl client
+      liftIO $ _addCredit ifc 10000000
+      _ <- _updateWindow ifc
+      reply <- open client "127.0.0.1" [] (Timeout 100) encoding decoding
+        (singleRequest (RPC :: RPC Arithmetic "add") vals )
+
+      liftIO $ print reply
+

examples/src/ArithServer.hs

@@ -0,0 +1,51 @@
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE DataKinds #-}
+module ArithServer where
+
+import Network.GRPC.Server
+import Lens.Micro
+import Lens.Micro.Extras
+import Data.ProtoLens.Message (defMessage)
+import Network.Wai.Handler.WarpTLS 
+import Network.Wai.Handler.Warp (defaultSettings, getPort)
+import Network.GRPC.HTTP2.ProtoLens (RPC(..))
+import Network.GRPC.HTTP2.Encoding (gzip)
+import Proto.Protos.Calcs (Arithmetic, CalcNumbers, CalcNumber)
+import Proto.Protos.Calcs_Fields 
+import System.Environment (getArgs)
+
+-- Eoin Cavanagh, modified from https://github.com/lucasdicioccio/warp-grpc-example/blob/master/src/Lib.hs
+
+someFunc :: IO ()
+someFunc = do
+  args <- getArgs
+  someFunc' args
+
+someFunc' :: [String] -> IO ()
+someFunc' p =  do
+  print $ "starting on port " ++ ((show . getPort) defaultSettings)
+  -- for simplicity, configures Warp to support insecure sessions
+  -- not recommended for production use
+  let insecureTlsSettings = defaultTlsSettings { onInsecure = AllowInsecure }
+  runGrpc insecureTlsSettings defaultSettings (handlers p) [gzip]
+
+handlers :: [String] -> [ServiceHandler]
+handlers _ =
+  [unary  (RPC :: RPC Arithmetic "add") handleAdd
+  ]
+
+
+-- sum up the values provided in the request and return the total
+handleAdd :: UnaryHandler IO CalcNumbers CalcNumber
+handleAdd _ input = do
+    let vals =  view values input
+    print ("add"::[Char], vals)
+    print (show vals)
+    return $ performAdd input
+
+performAdd :: CalcNumbers -> CalcNumber
+performAdd nums = defMessage & code .~ total
+  where
+    total = sum (toListOf (values . traverse . code) nums)
+