Which .NET ORM - Dapper or Entity Framework?

Within the .NET ecosystem, two ORMs dominate, the lightweight Dapper (open source) and the fully featured Entity Framework (EF) by Microsoft. 

Depending on your project's size and requirements, either of these should work well for you, but there are definitely some known cases where each is a better fit. That's what we're discussing in this post.

When to use Dapper?

• Small to medium size projects. It has low overhead in terms of setup and configuration.
• The database tables are in place already and you're calling existing stored procedures. This is known as a data first approach.
• You prefer to hand code the SQL for speed, optimization or fine tuning.

When to use Entity Framework?

• Its a large and/or enterprise type project.
• The database hasn't been created yet and you'd like to use a code first approach. The framework will create the database for you after you code the data models.
• You want the ORM to handle transactions for you in the background.
• You need to use the power of C# LINQ (Language Integrated Query), whereby SQL joins and other queries are generated for you based on your C# code.

Other important factors

• Is your project likely to change frameworks, or need to be adapted to other databases? If yes I'd favour Dapper, because there's just less to migrate and configure. Dapper tries to not get in the way. There are no  additional abstractions and class models that happens with EF.
• Are you using .NET Core? Its probably a controversial opinion but I feel that .NET Core as a framework is still quite unstable compared to the original .NET Framework. So when a new version comes out, there's normally breaking changes within EF Core. For that reason I'd also favour Dapper over EF for .NET Core projects.

What's not a factor?

• Speed and performance. There's no longer any significant performance difference between Dapper and EF. Issues with performance are more likely to be something else that's not being done correctly at the SQL level, such as a lack of indexing, or an incorrect query.
• The origin of the framework. The first release EF for .NET which came out in the 2000s had terrible performance. Since that time, all the performance issues have been fixed.

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Does Xamarin owe its existence to Unity & Apple?

Yes, Xamarin owes its existence to two other bits of technology that were huge around 2008 - the Unity Game Engine and the iPhone. The reason is that a confluence of events around 2008 provided the push to get the Mono project into mobile app development. This resulted in MonoTouch (for iOS) and Mono for Android, which eventually became Xamarin as we know it today.

The Mono project was founded in 2001 as a free open source implementation of Microsoft's .NET framework on Linux. But Mono had struggled since its inception to find its reason for being. According to Mono's founder, Miguel De Icaza, the hardcore free open source community never fully got behind Mono. The FOSS community feared that Microsoft would eventually cause problems for Mono, due to Microsoft being the creator of .NET. 

Outside of the Linux world however were other more pragmatic people from the MacOSX world who had no problem with Mono. One of these people was Joachim Ante, from Unity. Around 2005 the Unity game engine was just starting out and had a performance problem - their original scripting language of Python was far too slow - they needed something that was an order of magnitude faster. So Unity decided to replace the Python scripting with Mono/C# and immediately got all the performance they needed. This was the early days when the Unity Game Engine ran on MacOSX only. Mono filled the need of being a free open source JIT compiler with the modern language of C#.

Fast forward to 2008 when the iPhone App Store launched; Unity quickly set their sights on being able to compile games for the iPhone. Unity wanted to use Mono, but the additional requirement was that it had to be statically compiled for iOS, because Apple had banned the use of JIT (Just In Time) compilers in iOS Apps.

Unity comes back to us and says “Hey, we have this product on iOS, we need .NET to be statically compiled. Can you do that?” We were like, “Oh, that’s kind of impossible. Well, let’s think about it.”

One of our guys, Zoltán Varga - they went and made a static compiler for .NET, and it was amazing. We gave it to Unity. At this point, Unity is probably four or five employees.
    
They were working at somebody’s garage. And they shipped their product for iOS, built games for iOS using this thing, this 3D tech. They were the kings of this space.
    
- Miguel De Icaza (Xamarin)

Within a year of the iPhone App Store launch, Unity went from 4-5 employees to 80 employees. The iPhone and the App Store had launched Unity's massive growth, and along with this the Mono project had finally found its reason for being - mobile apps. The Mono developers realised there was interest in using .NET for mobile apps - so using the same tech given to Unity, they built their own product - MonoTouch, which allowed developers build native iOS apps using C#. Soon afterward, Mono turned its attention to Android and created Mono for Android.

Mobile app development was new and there were many developers who wanted to get into mobile apps but didn't really want to have to learn Objective-C and Java. So Mono now had a C# based cross platform app development platform with truly native performance. This was the killer combination that ensured Mono would take off in popularity.

The developers behind Mono founded the Xamarin company in 2011, MonoTouch became Xamarin.iOS and Mono for Android became Xamarin.Android. Xamarin was acquired by Microsoft in February 2016 and became a subsidiary of Microsoft, fully focused on the development of Xamarin's open source projects.

Inspiration for this article:

The History of GNOME, Mono, and Xamarin
https://changelog.com/podcast/275

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Programming Bitcoin Cash (BCH) with the NBitcoin .NET library and C#

The NBitcoin library is the most active and well supported library in .NET for working with Bitcoin and other similar cryptocurrencies.

NBitcoin fully supports Bitcoin Cash (BCH), however the ebook and programming guide examples focus solely on Bitcoin Core (BTC).

The problem you encounter when following the NBitcoin guide is firstly that the QBitNinja API only supports Bitcoin Core and secondly that broadcasting the transaction seems to require either running a full local node or using the QBitNinja API.

In this tutorial I'll show you how to spend your Bitcoin Cash using the NBitcoin library running under dotnet core, without the need for running a full local node or for accessing the QBitNinja API.

The program you write here will create a new transaction, sign it with your private key, and broadcast it to the Bitcoin Cash network.

Dotnet core is the preferred programming environment for NBitcoin. Dotnet core is open source and runs under the Linux, MacOSX and Windows operating systems.

Bitcoin Cash is the ideal cryptocurrency for experimenting with programming APIs and libraries - you can send small transactions for very low fees, typically for a fraction of one US cent.


Step 1: Project Setup

Follow the setup guide as normal:
https://programmingblockchain.gitbook.io/programmingblockchain/introduction/project_setup

The rest of these steps 2-12 below loosely follow the "Spend Your Coin" guide:
https://programmingblockchain.gitbook.io/programmingblockchain/bitcoin_transfer/spend_your_coin

Its not absolutely required, but for a more complete and in depth understanding, I would recommend you read through the "Spend Your Coin" guide above (with the knowledge that it applies to Bitcoin Core) before proceeding with the rest of the below steps.


Step 2: Add support for Bitcoin Cash

On the command line:

dotnet add package NBitcoin.Altcoins

The code - add these using statements to the top of the C# source file.

using NBitcoin;
using NBitcoin.Altcoins;
using NBitcoin.Protocol;

And at the beginning of the program, add this:

// Important Note - this is not test code.
// It is going to run in production (called the "mainnet").
var network = NBitcoin.Altcoins.BCash.Instance.Mainnet;


Step 3: (Optional) Generate a new private key and address

The below code snippet generates a new BCH private key and BCH address using the NBitcoin library.
  
// Generate a random private key.
Key rawPrivateKey = new Key();

// The private key, also known as the Bitcoin secret or the WIF (Wallet Interchange Format).
// If you intend to use it, make sure you save the below somewhere safe!
BitcoinSecret privateKey = rawPrivateKey.GetBitcoinSecret(network);
Console.WriteLine("privateKey = " + privateKey);
Console.WriteLine("address (from privateKey) = " + privateKey.GetAddress(ScriptPubKeyType.Legacy));

Alternatively you can generate a new private key and address using BCH wallet software.


Step 4: Setup the variables for your private keys and addresses

To spend your Bitcoin Cash, you'll need to know the private keys of both the "destination" BCH address and the "from" BCH address.
The "from" BCH address is also known as the input address or the outpoint to spend.

Here's the code to setup the address and private keys of both the "destination" address and the "from" address.

// Destination - private key and address. The destination of the new transaction we are creating.
// Note: its not strictly necessary for creating the transaction to have the private key of the destination,
// but its better to add it here so that you know that you have access to it, and that the money won't be 'lost'.
var privateKey = new BitcoinSecret("PASTE_YOUR_DESTINATION_ADDRESS_PRIVATE_KEY_HERE", network);
Console.WriteLine("dest privateKey = " + privateKey);
var address = privateKey.GetAddress(ScriptPubKeyType.Legacy);
Console.WriteLine("dest address = " + address);
Console.WriteLine("dest address scriptPubKey= " + address.ScriptPubKey);

// Input Transaction - private key and address. The from address.
var inPrivateKey = new BitcoinSecret("PASTE_YOUR_FROM_ADDRESS_PRIVATE_KEY_HERE", network);
var inAddress = inPrivateKey.GetAddress(ScriptPubKeyType.Legacy);
Console.WriteLine("inPrivateKey = " + inPrivateKey);
Console.WriteLine("inAddress = " + inAddress);
Console.WriteLine("inAddress scriptPubKey= " + inAddress.ScriptPubKey);

You can run the program now to make sure its working - on the command line:

dotnet run


Step 5: Determine the Transaction ID of the "from" address

Now you need to determine the transaction ID and index number of your "from" address by looking at the transaction in a blockchain explorer and plugging in the correct TxId and index number below.

// Determine the previous output that will be spent, as the Input to our new transaction.
// For example:
// https://explorer.bitcoin.com/bch/tx/292f70e71f8bc2e94b7c0ac46c4e89371dc59b821639de67376f6f0b09544d92
string txInIdString = "292f70e71f8bc2e94b7c0ac46c4e89371dc59b821639de67376f6f0b09544d92";
uint txOutIndex = 0; // <== Ensure this index is correct!
OutPoint outPointToSpend = OutPoint.Parse(txInIdString + ":" + txOutIndex);


Step 6: Create the new transaction

var transaction = Transaction.Create(network);
transaction.Inputs.Add(new TxIn()
{
    PrevOut = outPointToSpend
});


Step 7: Setup the amount to spend and the miner fee

// Suggested miner fee for this transaction, as of February 2020,
// is 0.000003 BCH or around USD 0.001 (a tenth of a cent).
// Check recent blocks for guidance.
var minerFee = new Money(0.000003m, MoneyUnit.BTC);  

// Replace below with your amount.
// It is the total unspent amount of the "from" address.
var txInAmount = new Money(0.0021m, MoneyUnit.BTC);

// Move to the destination address.
var spendAmount = txInAmount - minerFee;
transaction.Outputs.Add(spendAmount, address.ScriptPubKey);


Step 8: Add a message to the transaction, using the OP_RETURN template (max 80 characters)

var message = "Test 1: using the NBitcoin library to move Bitcoin Cash. BCH Rocks!";
var bytes = Encoding.UTF8.GetBytes(message);
transaction.Outputs.Add(Money.Zero, TxNullDataTemplate.Instance.GenerateScriptPubKey(bytes));


Step 9: Sign the transaction

// Get the ScriptPubKey from the private key of the outPointToSpend.
transaction.Inputs[0].ScriptSig = inAddress.ScriptPubKey;

// Sign the transaction with the input private key.
var txInId = uint256.Parse(txInIdString);
var inCoin = new Coin(txInId, txOutIndex, txInAmount, inAddress.ScriptPubKey);
transaction.Sign(inPrivateKey, inCoin);


Step 10: Determine the TxId of your transaction, which is just its hash

Console.WriteLine("New TxId: " + transaction.GetHash());

Now is a good time to run the code and check its all working. From the command line:

dotnet run


Step 11: Broadcast your transaction to the Bitcoin Cash network

This is the final step and should only be attempted if your program runs fine up to step 10.

Before you run it, confirm your amount to spend is correct.

//
// Connect to a BCH node and broadcast the transaction.
// See here for the DNS Seed list:
// https://github.com/Bitcoin-ABC/bitcoin-abc/blob/master/src/chainparams.cpp
//
using (var node = Node.Connect(network, "seed.bchd.cash:8333"))
{
    // Say hello to the node.
    node.VersionHandshake();

    // Advertise your transaction (send just the hash).
    node.SendMessage(new InvPayload(InventoryType.MSG_TX, transaction.GetHash()));

    // Send the contents of the transaction.
    node.SendMessage(new TxPayload(transaction));

    // Wait for the message to be sent.
    Thread.Sleep(5000);
}

Run your program the command line:

dotnet run


Step 12: That's it, well done for making it to the end!!

If everything went well, your new transaction was accepted by the Bitcoin Cash network, and it will show up in a block explorer such as this one:

https://explorer.bitcoin.com/bch/tx/3ecf0f0dafd26e8d788b59a433bf00e1c3c079e82dada5111e899c87a75dadff

Replace the above TxId with yours from step 10.

Your new transaction will be listed initially as having 0 confirmations, which means its in the mempool.

Now you just need to wait for your transaction to be confirmed. This will happen as soon as the next block is mined and your transaction gets added to that block by the winning miner.

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Anders Hejlsberg: C# stands for C++++

Just came across this today. Previously had heard the association with the musical sharp symbol (#) to mean a pitch higher in tone, but this was the first time I'd heard that the # symbol can also be seen as a matrix of four small + symbols, hence C# stands for C++++, i.e. an increment to C++.

Source: http://www.computerworld.com.au/article/261958/a-z_programming_languages_c_/?pp=2

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TCP/IP Sockets in .NET 4

TCP is one of the core protocols of the Internet and is a bi-directional, client/server protocol. In .NET you can use the TcpListener Class for the server component, which provides simple methods that listen for and accept incoming connection requests from clients. You can use the TcpClient Class for the client component, which provides client connections to TCP server components; it provides simple methods for connecting, sending, and receiving stream-based data over the network.

Here's a standalone C# 4.0 app that demonstrates how to setup a TCP/IP sockets based client and server in .NET. It uses a command line option to determine whether to run the client or server. There's no external files or libraries needed, just the standard ones you get with a C# 4.0 console project. I've tested it with Visual Studio 2010 in Windows, and it will also work unchanged with Mono.

To run the server, from the command prompt...
   SocketsTest -server

To run the client, from another command prompt ...
   SocketsTest -client

Below is the source code ...

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Threading.Tasks;

/// 

/// Standalone TCP/IP sockets example using C#.NET 4.0
/// 
/// 
/// Compile as a C#.NET console mode application
/// 
/// Command line usage:
///   SocketsTest -client   => run the client
///   SocketsTest -server   => run the server
/// 
class SocketsTest
{
    static TcpListener listener;

    // Sample high score table data
    static Dictionary<string, int> highScoreTable = new Dictionary<string, int>() { 
            { "john", 1001 }, 
            { "ann", 1350 }, 
            { "bob", 1200 }, 
            { "roxy", 1199 } 
    };

    static int Port = 4321;
    static IPAddress IP_ADDRESS = new IPAddress(new byte[] { 127, 0, 0, 1 });
    static string HOSTNAME = "127.0.0.1";
    static int MAX_CLIENTS = 5;

    public static void Main(string[] args)
    {
        if (args.Contains("-server"))
        {
            ServerMain();
        }
        else if (args.Contains("-client"))
        {
            ClientMain();
        }
        else
        {
            Console.WriteLine("Usage: SocketsTest -client   => run the client");
            Console.WriteLine("       SocketsTest -server   => run the server");
        }
    }

    /// 

    /// Server receives player name requests from the client and responds with the score.
    /// 
    private static void ServerMain()
    {
        listener = new TcpListener(IP_ADDRESS, Port);
        listener.Start();
        Console.WriteLine("Server running, listening to port " + Port + " at " + IP_ADDRESS);
        Console.WriteLine("Hit Ctrl-C to exit");
        var tasks = new List();
        for (int i = 0; i < MAX_CLIENTS; i++)
        {
            Task task = new Task(Service, TaskCreationOptions.LongRunning);
            task.Start();
            tasks.Add(task);
        }
        Task.WaitAll(tasks.ToArray());
        listener.Stop();
    }

    private static void Service()
    {
        while (true)
        {
            Socket socket = listener.AcceptSocket();

            Console.WriteLine("Connected: {0}", socket.RemoteEndPoint);
            try
            {
                // Open the stream
                Stream stream = new NetworkStream(socket);
                StreamReader sr = new StreamReader(stream);
                StreamWriter sw = new StreamWriter(stream);
                sw.AutoFlush = true;

                sw.WriteLine("{0} stats available", highScoreTable.Count);
                while (true)
                {
                    // Read name from client
                    string name = sr.ReadLine();
                    if (name == "" || name == null) break;

                    // Write score to client
                    if (highScoreTable.ContainsKey(name))
                        sw.WriteLine(highScoreTable[name]);
                    else
                        sw.WriteLine("Player '" + name + "' was not found.");

                }
                stream.Close();
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }

            Console.WriteLine("Disconnected: {0}", socket.RemoteEndPoint);
            socket.Close();
        }
    }

    /// 

    /// Client requests a player name's score from the server.
    /// 
    private static void ClientMain()
    {
        TcpClient client = new TcpClient(HOSTNAME, Port);
        try
        {
            // Open the stream
            Stream stream = client.GetStream();
            StreamReader sr = new StreamReader(stream);
            StreamWriter sw = new StreamWriter(stream);
            sw.AutoFlush = true;

            // Read and output the first line from the service, which
            // contains the number of players listed in the table.
            Console.WriteLine(sr.ReadLine());

            while (true)
            {
                // Input player name
                Console.Write("Enter player name: ");
                string name = Console.ReadLine();

                // Write name to server
                sw.WriteLine(name);
                if (name == "") break;

                // Read score from server
                Console.WriteLine(sr.ReadLine());
            }
            stream.Close();
        }
        finally
        {
            // Close the connection
            client.Close();
        }
    }
}

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