Exploring .NET Core 1.0

After a busy year working on coding up REST services with ASP.NET Web API 2.0 and doing zero blogging, I’m finally taking a little time to explore the .NET Core 1.0 bits released recently in RC2 and watching a number of presentations. I’m very excited about what I’m learning and will blog more about it but here’s a list of links that I’ve found most instructive and useful.

First, the announcement of RC2: announcing-asp-net-core-rc2

Next, the install: https://www.microsoft.com/net 

The unforgettable Scotts at TechEd: Introducing ASP.NET Core 1.0 

And the ASP.NET Core Deep Dive into MVC that followed.

After some experimentation with the preview tooling, trying to figure out how to create a .NET Core class library NuGet package was made easier with this very helpful article: how-to-create-a-nuget-package-with-your-library

And understanding the IIS deployment story was made so much more clear just the other day by the always helpful Rick Strahl: Publishing-and-Running-ASPNET-Core-Applications-with-IIS

Then I went looking for something similar for using Apache as the reverse proxy in front of a Kestrel app and found this: linuxproduction

Which finally led me to clone the KestrelHttpServer.

Exploring the code and the repo has been interesting. I especially noted with interest the recent pull request to Downtarget Kestrel to NETStandard 1.3.

The comment that Kestrel needed no functionality beyond 1.3 and that this allowed greater flexibility with current scenarios was very interesting.

The most important piece of learning so far has been the very brief discussion of the Libuv library used by Kestrel: http://libuv.org/

This amazing little library is used by Node.js and now by the ASP.NET Core web server called Kestrel and according to reports in Microsoft presentations has served up 3.2 million requests per second on a single bare metal machine. Even with a beefy machine, that is impressive.

Seeing how Kestrel uses Libuv is even more interesting and makes me think I ought to explore it as the next engine for a ServiceWire and ServiceMq implementation that could be deployed as a Docker container.

I was especially interested to see how .NET Core 1.0 utilizes native libraries in the Kestrel integration and use of Libuv as a NuGet package: KestrelHttpServer Internal Networking

The runtimes contained in the Libuv package used by Kestrel were also interesting to note:

libuv_runtimes

This concludes about a week of research on the side where I could sneak in an hour or two here or there. I’m eager to keep learning.

A Software Development Allegory

Farmer Brown has a tractor. Farmer Jones has a tractor. Both tractors break down every Monday.

Farmer Brown spends every Monday afternoon fixing his tractor and then gets a good five days of work in before he rests on Sunday.

Farmer Jones spends Monday afternoon evaluating the tractor and Monday evening discussing it with his wife writing up a plan and reviewing that plan for fixing it.

Tuesday morning Farmer Jones goes to the diner for coffee and a donut and to discuss his tractor woes with his pals, showing off his plan for fixing the tractor. One of the pals suggests it might not a problem with the doohickey as Farmer Jones suspects. He recommends that Farmer Brown take the tractor to the mechanic for further diagnosis and discussion. So Farmer Jones spends the rest of the day loading up his tractor onto the trailer and hauling it into town whereupon the mechanic tells him he can get to it first thing in the morning.

On Wednesday morning after coffee at the diner, Farmer Jones ambles on over to the mechanic shop and learns that the problem was indeed what he had suspected all along and that he could have fixed the problem in an hour or two on Monday afternoon. So farmer Jones loads up the tractor and takes it home only to find that his wife has baked a nice apple pie and so he spends a lazy afternoon eating pie and talking with his wife and the neighbor who has come over to gossip. That evening he fixes the tractor.

Now first thing Thursday morning, Farmer Jones gets to work and works through Sunday, making his wife cross with him for not attending Services at the church. Farmer Jones is too tired to listen and flops down in bed in need of rest.

And on Monday morning both tractors break down again.

Farmer Brown gets 20% more work done and rests one day a week.

Farmer Jones later gives up on farming and gets a job managing the parts store at the mechanic shop.

What kind of farmer are you?

Hiberfile.sys Removal Note to Self

A very large portion of my system drive, a 250GB SSD, seemed to be gobbled up with my fresh Windows 8.1 install and after install all my tools, I was fast running out of disk space on the C: drive. A quick search for culprits using Effective Search from SowSoft turned up a 64GB file called hiberfil.sys.

After a little hunting and poking, I found the GUI for power management options and tried to turn off hibernate. But that did not get rid of the file.

Not until I found and used the following in an “as Administrator” cmd window did I recover the 64GB of SSD space:

powercfg -h off

And yes, I have 64GB of RAM. Call me spoiled.

MongoDB C# Driver 2.0 AsQueryable Alternative

I’m a fan of LINQ and the IQueryable<T> interface power to compose dynamic queries based on input parameters. So when I needed to compose just such a query in a repository for a MongoDB collection, I found that the MongoDB C# 2.0.1 driver is currently missing the AsQueryable method which is slated for 2.1 release of the driver.

After a little searching, I found the Filter Definition Builder documentation and a happy alternative to building up or composing a query based on the presence of query parameters.

And here is a code sample:

public async Task<IEnumerable<MyData>> GetByQuery(MyDataQuery query)
{
    var filter = ComposeFilter(query);
    if (!query.Ascending)
    {
        var responses = await _invoiceCollection
            .Find(filter)
            .SortByDescending(x => x.TransactionDate)
            .Skip(query.Index)
            .Limit(query.Limit)
            .ToListAsync();
        return responses;
    }
    var ascResponses = await _invoiceCollection
        .Find(filter)
        .SortBy(x => x.TransactionDate)
        .Skip(query.Index)
        .Limit(query.Limit)
        .ToListAsync();
    return ascResponses;
}

private FilterDefinition<MyData> ComposeFilter(MyDataQuery query)
{
    var builder = Builders<MyData>.Filter;
    var filter = builder.Eq(x => x.CustomerId, query.CustomerId);
    if (query.StartDate.HasValue)
    {
        filter = filter & builder.Gte(x => x.TransactionDate, query.StartDate.Value);
    }

    if (query.EndDate.HasValue)
    {
        filter = filter & builder.Lt(x => x.TransactionDate, query.EndDate.Value);
    }

    if (query.InvoiceId != null)
    {
        filter = filter & builder.Eq(x => x.InvoiceID, query.InvoiceId);
    }

    if (query.ItemId != null)
    {
        filter = filter & builder.Eq(x => x.ItemID, query.ItemId);
    }
    return filter;
}

So now you have a dynamic query based on composition logic. Of course this is a very simple example and there are bound to be far more sophisticated ways of doing the same thing, but I found this one worked very well for me.

Microsoft Graph Engine

This tweet from Scott Hanselman caught my eye because I spent nearly all of 2014 working on a graph solution for my employer that had it’s genesis in my study of Neo4J but primarily in my reading of this Microsoft Research paper (Sakr, Elnikety, and He) produced in 2012.

graphtweet

The essence of the Microsoft Research paper is storing edges (node relationships) in memory. So that’s what I did with unmanaged memory allocated in blocks using the Marshal.AllocHGlobal method. My own efforts were very specific with respect to my employer’s needs at the time and not really useable as a general purpose tool, so I was very pleased to see that Microsoft Research had an ongoing project called Trinity working to produce a more general purpose tool based on many of the same concepts originally explored by Sakr, Elnikety and He.

That tool was recently quietly released as the Microsoft Graph Engine. I’ve only had a little time to explore and understand it and look forward to spending more time using it soon. The essence is the same. Store the data in sequential chunks in raw unmanaged memory. Graph Engine uses Visual Studio to generate code on the fly using a meta language called Trinity Specification Language (TSL). Have a look through the documentation. If you’re considering graph database work, put Microsoft’s Graph Engine on your list of items to evaluate.

Blog Vacation is Over

It's been seven months and two job changes and crazy busy with family, work and life.

Vacation is over.

List of things to blog about.

So much to say, so little time to say it.

Git and PowerShell Environment Setup Notes

As a visually oriented developer, I remain command-line challenged. And yet there are some things that seem to be more productive in command-line form, and git seems to be one of them. I’ve not tried every GUI incarnation of a git tool, so I would be happy to be proven wrong about that. Until then, here are my notes on setting up my local machine with Git and PowerShell.

1. Download and install GitHub for Windows from https://windows.github.com/.

2. Create this directory: {home}\Documents\WindowsPowerShell

3. Add this file: profile.ps1 with these lines:

  • $env:path += ";" + (Get-Item "Env:ProgramFiles(x86)").Value + "\Git\bin"
  • $env:PSModulePath = $env:PSModulePath + ";{home}\Documents\WindowsPowerShell\Modules"

Where {home} is your user home directory.

4. Run PowerShell as Admin with following three commands (individually):

5. In PS, navigate to a local git repository directory. And let the magic begin.

6. Review http://think-like-a-git.net/ for a refresher.

Update: Change colors for better contrast, at least for my eyes.

gitcolor

A. Edit the GitPrompt.ps1 file in {home}\Documents\WindowsPowerShell\Modules\posh-git directory. Delete the “Dark” text from the colors.

B. Edit the .gitconfig file in the {home}\ directory and add the following lines to taste:

[core]
  quotepath = false
  whitespace=fix,-indent-with-non-tab,trailing-space,cr-at-eol
[color]
  diff = auto
  status = auto
  branch = auto
  interactive = auto
  ui = true
  pager = true
[color "branch"]
  current = yellow bold
  local = yellow
  remote = red
[color "diff"]
  meta = yellow bold
  frag = red bold
  old = red reverse
  new = green reverse
  whitespace = white reverse
[color "status"]
  added = yellow
  changed = green
  untracked = cyan reverse
  branch = red

Thanks and credit to many sources for coloring, but in particular to David DeSandro.

Very Large Pseudo Random Number Generator in C#

Thanks to a friend of mine, over the past few weeks the idea of zero knowledge authentication, which has been around for a long time but to which I’d never paid any attention, has been percolating in my head. Finally on Thursday (Thanksgiving holiday here in the U.S.), I dove in and added it to ServiceWire.

Now you can secure your ServiceWire RPC calls without PKI or exchanging keys or exposing a password across the wire. It validates on the server that the client knows the secret key (password) and on the client that the server knows the secret key. It creates a shared encryption key that is used for that one connection session and is never passed across the wire, allowing all subsequent communications between client and server to be encrypted with strong and fast symmetric encryption, denying any man in the middle from access to the data or even the service definition.

But this post is not about the entire zero knowledge addition to ServiceWire. Instead I want to share one part of that addition which you may use to create a very large random number. In this case, 512 bytes (that’s 4096 bits for those of you who can only count to 1). If you want a larger random number, you’ll need a larger safe prime from a Sophie Germain prime. In ServiceWire, I only include the 512 byte safe prime. There are a number of sources for larger safe primes freely available on the web.

This is not an algorithm entirely of my invention. It is based on several different algorithms I studied while investigating zero knowledge secure remote password protocols. I did take some liberties by adding a randomly selected smaller safe prime as the exponent in the algorithm.

And here’s the code:

using System.Numerics;

public class ZkProtocol
{
   private readonly SHA256 _sha;
   private readonly Random _random;
   private readonly BigInteger _n;

   public ZkProtocol()
   {
      _sha = SHA256.Create(); //used in other protocol methods
      _random = new Random(DateTime.Now.Millisecond);
      _n = new BigInteger(ZkSafePrimes.N4);
   }
   
   //...other protocol methods excluded for post

   /// <summary>
   /// Generate crypto safe, pseudo random number.
   /// </summary>
   /// <param name="bits">max value supported is 4096</param>
   /// <returns></returns>
   public byte[] CryptRand(int bits = 4096)
   {
      var rb = new byte[256];
      _random.NextBytes(rb);
      var bigrand = new BigInteger(rb);
      var crand = BigInteger.ModPow(bigrand, 
         ZkSafePrimes.GetSafePrime(_random.Next(0, 2047)), _n);
      var bytes = crand.ToByteArray();
      if (bits >= 4096) return bytes;
      var count = bits / 8;
      var skip = _random.Next(0, bytes.Length - count);
      return bytes.Skip(skip).Take(count).ToArray();
   }
}

internal static class ZkSafePrimes
{
   internal static byte[] N4
   {
      get { return Safe4096BitPrime; }
   }

   private static byte[] Safe4096BitPrime = new byte[]
   {
      //data not shown here for post (see on GitHub)
   };
   
   public static int GetSafePrime(int index)
   {
      if (index < 1) index = 1;
      else if (index > 2047) index = 2047;
      else if (index % 2 == 0) index++;
      return _safePrimes[index];
   }

   //2048 values, every second value is a safe primes 
   //the previous value is the Sophie Germain prime
   //as in q is the Sophie Germain and N = 2q+1 is safe
   private static int[] _safePrimes = new[]
   {
      5903,11807,8741,17483 //first four value only - see GitHub
   };
}

See the code on GitHub. Look specifically at the ZkProtocol and ZkSafePrimes classes.

I should note that in ServiceWire a new instance of ZkProtocol is used for each connection, so the Random object should provide a healthy random seed to the algoritm given the clock's milliseconds seed on construction. If you find this useful, I would love to hear from you.