Example application (non RPC)

Assuming that you've installed the Cap'n Proto tool set and the C# code generator back end (as described in README.md), save the following schema definition into a file named AddressBook.capnp:

@0xebf92c49b1687ddb;

struct Person {
  id @0 :UInt32;
  name @1 :Text;
  email @2 :Text;
  phones @3 :List(PhoneNumber);

  struct PhoneNumber {
    number @0 :Text;
    type @1 :Type;

    enum Type {
      mobile @0;
      home @1;
      work @2;
    }
  }

  employment :union {
    unemployed @4 :Void;
    employer @5 :Text;
    school @6 :Text;
    selfEmployed @7 :Void;
    # We assume that a person is only one of these.
  }
}

struct AddressBook {
  people @0 :List(Person);
}

Open a command line with current directory set to the location of AddressBook.capnp. Type:

capnp compile -ocsharp .\AddressBook.capnp

If everything worked as expected, you will find a generated AddressBook.capnp.cs.

Create a new .NET Console application (either .NET Framework >= 4.7.2 or .NET Core >= 2.1) with VisualStudio. Open the NuGet package manager console and type:

Install-Package Capnp.Net.Runtime

Add AddressBook.capnp.cs from the previous step to your project. The following Program.cs snippet demonstrates how to create a domain class instance, serialize it to a stream, and how to deserialize it again:

using System;
using System.IO;
using Capnp;
using CapnpGen;

namespace MyAddressBook
{
    class Program
    {
        static void Main(string[] args)
        {
            var addressBook = new AddressBook()
            {
                People = new Person[]
                {
                    new Person()
                    {
                        Id = 1234,
                        Name = "Mark Harthaw",
                        Email = "mark.harthaw@soylent.corp",
                        Phones = new Person.PhoneNumber[]
                        {
                            new Person.PhoneNumber() { TheType = Person.PhoneNumber.Type.work, Number = "12345678" },
                            new Person.PhoneNumber() { TheType = Person.PhoneNumber.Type.mobile, Number = "87654321" }
                        },
                        Employment = new Person.employment()
                        {
                            Employer = "Soylent Corp"
                        }
                    },
                    new Person()
                    {
                        Id = 4321,
                        Name = "John Doe",
                        Employment = new Person.employment()
                        {
                            which = Person.employment.WHICH.SelfEmployed
                        }
                    }
                }
            };

            var msg = MessageBuilder.Create();
            var root = msg.BuildRoot<AddressBook.WRITER>();
            addressBook.serialize(root);

            var mems = new MemoryStream();
            var pump = new FramePump(mems);
            pump.Send(msg.Frame);
            mems.Seek(0, SeekOrigin.Begin);

            var frame = Framing.ReadSegments(mems);

            var deserializer = DeserializerState.CreateRoot(frame);
            var reader = new AddressBook.READER(deserializer);

            foreach (var person in reader.People)
            {
                Console.WriteLine($"Id: {person.Id}");
                Console.WriteLine($"Name: {person.Name}");
                Console.WriteLine($"E-mail: {person.Email}");
                if (person.Phones?.Count > 0)
                {
                    foreach (var phone in person.Phones)
                    {
                        Console.WriteLine($"{phone.TheType}: {phone.Number}");
                    }
                }
                Console.WriteLine($"Employment: {person.Employment.which}");
                switch (person.Employment.which)
                {
                    case Person.employment.WHICH.Employer:
                        Console.WriteLine($"Employer: {person.Employment.Employer}");
                        break;

                    case Person.employment.WHICH.School:
                        Console.WriteLine($"School: {person.Employment.School}");
                        break;
                }
            }

            Console.ReadLine();
        }
    }
}

Enjoy!