Merge pull request #1716 from jtattermusch/update_readme

Update C# readme

src/csharp/README.md

@@ -6,7 +6,7 @@ A C# implementation of gRPC.
 Status
 ------
 
-Ready for early adopters.
+Alpha : Ready for early adopters.
 
 Usage: Windows
 --------------
@@ -19,22 +19,60 @@ Usage: Windows
   That will also pull all the transitive dependencies (including the native libraries that
   gRPC C# is internally using).
 
-- TODO: link to Helloworld example
+- Helloworld project example can be found in https://github.com/grpc/grpc-common/tree/master/csharp.
 
 Usage: Linux (Mono)
 --------------
 
-- Prerequisites: Mono framework, MonoDevelop 5.9 with NuGet add-in installed.
+- Prerequisites: Mono 3.2.8+, MonoDevelop 5.9 with NuGet add-in installed.
 
-- Install gRPC C Core using instructions in https://github.com/grpc/homebrew-grpc
+- Install Linuxbrew and gRPC C Core using instructions in https://github.com/grpc/homebrew-grpc
 
-- TODO: explain using LD_LIBRARY_PATH or installation to /usr/local
+- gRPC C# depends on native shared library libgrpc_csharp_ext.so (Unix flavor of grpc_csharp_ext.dll).
+  This library will be installed to `~/.linuxbrew/lib` by the previous step.
+  To make it visible to mono, you need to:
+
+  - (preferred approach) add `libgrpc_csharp_ext.so` to `/etc/ld.so.cache` by running:
+
+    ```sh
+    echo "$HOME/.linuxbrew/lib" | sudo tee /etc/ld.so.conf.d/zzz_brew_lib.conf
+    sudo ldconfig
+    ```
+
+  - (adhoc approach) set `LD_LIBRARY_PATH` environment variable to point to directory containing `libgrpc_csharp_ext.so`:
+
+    ```sh
+    export LD_LIBRARY_PATH=$HOME/.linuxbrew/lib:${LD_LIBRARY_PATH}
+    ```
 
 - Open MonoDevelop and start a new project/solution.
 
 - Add NuGet package `Grpc` as a dependency (Project -> Add NuGet packages).
 
-- TODO: link to Helloworld example
+- Helloworld project example can be found in https://github.com/grpc/grpc-common/tree/master/csharp.
+
+Usage: MacOS (Mono)
+--------------
+
+- WARNING: As of now gRPC C# only works on 64bit version of Mono (because we don't compile
+  the native extension for C# in 32bit mode yet). That means your development experience
+  with Xamarin Studio on MacOS will not be great, as you won't be able to run your
+  code directly from Xamarin Studio (which requires 32bit version of Mono).
+
+- Prerequisites: Xamarin Studio with NuGet add-in installed.
+
+- Install Homebrew and gRPC C Core using instructions in https://github.com/grpc/homebrew-grpc
+
+- Install 64-bit version of mono with command `brew install mono` (assumes you've already installed Homebrew).
+
+- Open Xamarin Studio and start a new project/solution.
+
+- Add NuGet package `Grpc` as a dependency (Project -> Add NuGet packages).
+
+- *You will be able to build your project in Xamarin Studio, but to run or test it,
+  you will need to run it under 64-bit version of Mono.*
+
+- Helloworld project example can be found in https://github.com/grpc/grpc-common/tree/master/csharp.
 
 Building: Windows
 -----------------
@@ -47,9 +85,10 @@ If you are a user of gRPC C#, go to Usage section above.
 - The grpc_csharp_ext native library needs to be built so you can build the Grpc C# solution. You can 
   either build the native solution in `vsprojects/grpc.sln` from Visual Studio manually, or you can use
   a convenience batch script that builds everything for you.
-```
-buildall.bat
-```
+
+  ```
+  buildall.bat
+  ```
 
 - Open Grpc.sln using Visual Studio 2013. NuGet dependencies will be restored
   upon build (you need to have NuGet add-in installed).
@@ -61,11 +100,12 @@ Building: Linux & Mono
 You only need to go through these steps if you are planning to develop gRPC C#.
 If you are a user of gRPC C#, go to Usage section above.
 
-- Prerequisites for development: Mono framework, MonoDevelop 5.9 with NuGet and Nunit add-ins installed.
-```
-sudo apt-get install mono-devel
-sudo apt-get install nunit nunit-console
-```
+- Prerequisites for development: Mono 3.2.8+, MonoDevelop 5.9 with NuGet and NUnit add-ins installed.
+
+  ```sh
+  sudo apt-get install mono-devel
+  sudo apt-get install nunit nunit-console
+  ```
 
 You can use older versions of MonoDevelop, but then you might need to restore
 NuGet dependencies manually (by `nuget restore`), because older versions of MonoDevelop
@@ -73,10 +113,10 @@ don't support NuGet add-in.
 
 - Compile and install the gRPC C# extension library (that will be used via
   P/Invoke from C#).
-```
-make grpc_csharp_ext
-sudo make install_grpc_csharp_ext
-```
+  ```sh
+  make grpc_csharp_ext
+  sudo make install_grpc_csharp_ext
+  ```
 
 - Use MonoDevelop to open the solution Grpc.sln
 
@@ -95,7 +135,6 @@ Then you should be able to run all the test from the Test View.
 
 After building the solution, you can also run the tests from command line 
 using nunit-console tool.
-
 ```
 # from Grpc.Core.Test/bin/Debug directory
 nunit-console Grpc.Core.Tests.dll