How to fix issue "Unhandled Exception: System.TypeInitializationException: The type initializer for 'LibGit2Sharp.Core.NativeMethods' threw an exception. ---> System.BadImageFormatException: An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B)"

In the build definition:
Process => Build => Advanced => MSBuild argument
add:
/p:GenerateBuildInfoConfigFile=fals

Different encoding systems for "Hello" example:

ANSI
48 65 6C 6C 6F

Unicode (little-endian) encoding with no BOM.
48 00 65 00 6C 00 6C 00 6F 00

Unicode (little-endian) encoding with BOM
FF FE 48 00 65 00 6C 00 6C 00 6F 00

Unicode (big-endian) encoding with no BOM
00 48 00 65 00 6C 00 6C 00 6F

Unicode (big-endian) encoding with BOM
FE FF 00 48 00 65 00 6C 00 6C 00 6F

UTF-8 encoding
EF BB BF 48 65 6C 6C 6F

UTF-7 encoding
2B 2F 76 38 2D 48 65 6C 6C 6F



Reference:
http://blogs.msdn.com/b/oldnewthing/archive/2004/03/24/95235.aspx

How to fix issue "The target GatherAllFilesToPublish does not exist"?

#1 Option:
Add following tag into project file:
  <Target Name="GatherAllFilesToPublish">
  </Target>
But will output all of source files into web site.

#2 Option:
Replace
<Import Project="$(VSToolsPath)\WebApplications\Microsoft.WebApplication.targets" Condition="false"/>
To
<Import Project="$(VSToolsPath)\WebApplications\Microsoft.WebApplication.targets" Condition="'$(VSToolsPath)' != ''" />

Reference:
http://forums.asp.net/t/1838524.aspx?The+target+GatherAllFilesToPublish+does+not+exist

INTENTION REVEALING INTERFACES from DDD

Excerpt from DDD book:


"The beauty of objects is their ability to encapsulate all that so that client code is simple and can be interpreted in terms of higher-level concepts.
But if the interface doesn’t tell the client developer what he needs to know in order to use the object effectively, he will have to dig into the internals and understand the details. A reader of the client code will have to do that same. Then most of the value of the encapsulation is lost. We are always fighting cognitive overload. If the client developer’s mind is flooded with detail about how a component does its job, his mind isn’t clear to work out the intricacies of the client design. This is true even when the same person is playing both roles, developing and using his own code, because even if he doesn’t have to learn those details, there is a limit to how many factors he can consider at once."


It is so true if working on a larger dev team.

Another way to talk about CQRS/Event Sourcing

"A more promising model, used in some systems, is to think of a database as an always-growing collection of immutable facts. You can query it at some point in time — but that’s still old, imperative style thinking. A more fruitful approach is to take the streams of facts as they come in, and functionally process them in real-time."

Turning the database inside-out with Apache Samz
https://martin.kleppmann.com/2015/03/04/turning-the-database-inside-out.html

Covariant and Contravariant Types made simple

https://medium.com/@EdwhardT/covariant-and-contravariant-types-made-simple-4ab6effb031b

bitbucket

Free for small teams + Unlimited private repositories
https://bitbucket.org/

12 tips to increase the performance of your ASP.NET application drastically – Part 2

http://www.infragistics.com/community/blogs/brijmishra/archive/2015/08/21/12-tips-to-increase-the-performance-of-asp-net-application-drastically-part-2.aspx

How to swap two numbers without third variable?

int first,second ;
first = 1;
second = 2;
first = first + second;
second = first - second;
first = first - second;

Practicing Programming

https://sites.google.com/site/steveyegge2/practicing-programming

Practicing to make skills better, no problem, but many Programming technologies are going away all the time.

Architects Should Code: The Architect's Misconception

Architecture Spike

The architect could lead a development spike focused on architectural discovery or delivery. A spike is a functional, proof of concept implementation for some aspect of the architecture used to identify or mitigate risk by exploring a new technology.

http://www.infoq.com/articles/architects-should-code-bryson?utm_source=reddit&utm_medium=link&utm_campaign=external

Moving Fast With High Code Quality

https://engineering.quora.com/Moving-Fast-With-High-Code-Quality

How to solve log4net not writing into database problem

log4net not writing into database problem
Turn on debug, no problem found. At last, change bufferSize from 400 to 1
<bufferSize value="1" />
Everything is working fine.


References:
http://stackoverflow.com/questions/756125/how-to-track-down-log4net-problems

How to compare two tables schema by SQL query in MS SQL?

How to compare two tables schema  by SQL query in MS SQL?
SELECT name,system_type_id,user_type_id,max_length,precision,scale,collation_name,is_nullable into #Tablescehma1
FROM sys.columns WHERE object_id = OBJECT_ID('TABLE1')

SELECT name,system_type_id,user_type_id,max_length,precision,scale,collation_name,is_nullable into #Tablescehma2
FROM sys.columns WHERE object_id = OBJECT_ID('TABLE2')

select * from #Tablescehma1
except
select * from #Tablescehma2

Git Cheat sheet

http://itmyhome.com/git-sheet/

C# Algorithms source code

https://github.com/aalhour/C-Sharp-Algorithms

Secondary skills for software engineers

Secondary skills for software engineers
http://radek.io/2015/07/27/secondary-skills-for-software-engineers/

What are the most important skills?
1. Language(s)
2. Problem
3. Naming
4. Communication
??

In ASP.NET Logout: GET or POST?

In ASP.NET Logout: GET or POST?

I just switch from POST to GET, and tested in Chrome, no problem found for now
Suggestion from Stackoverflow
http://stackoverflow.com/questions/3521290/logout-get-or-post

What’s New in the IDE 2015

http://blogs.msdn.com/b/visualstudio/archive/2015/07/21/visual-studio-2015-rtm-what-s-new-in-the-ide.aspx

.NET Framework 4.6

.NET Framework 4.6
http://blogs.msdn.com/b/dotnet/archive/2015/07/20/announcing-net-framework-4-6.aspx

code golf

http://blog.zmxv.com/2015/07/code-golf-at-google.html

Mostly adequate guide to functional programming

http://drboolean.gitbooks.io/mostly-adequate-guide/content/

Introduce functional programming by JavaScript

The anatomy of a credit card form

Very detailed design for Credit Card payment

https://medium.com/user-experience-design-1/the-anatomy-of-a-credit-card-payment-form-32ec0e5708bb

Session in ASP.NET 5

http://www.exceptionnotfound.net/session-in-asp-net-5/

Long sentence

http://yarchive.net/blog/long_sentences.html

Long sentence =>
complicated sentence =>
- Need to remember context
- Not to extend and repeat previsoue idea

Binary tree search logic in pseudo code

  node search (node, key) {
       if node is null then return null;
     
       if node.key = key then
          return node
         
       if key < node then
          return search (node.left, key);
       else
          return search (node.right, key);

Reference:
http://www.codeproject.com/Articles/18976/A-simple-Binary-Search-Tree-written-in-C

How to solve problem "Inheritance security rules violated by type: 'System.Web.WebPages.Razor.WebPageRazorHost'. Derived types must either match the security accessibility of the base type or be less accessible."

How to solve problem "Inheritance security rules violated by type: 'System.Web.WebPages.Razor.WebPageRazorHost'. Derived types must either match the security accessibility of the base type or be less accessible."

This error happens after add Razor engine into ASP.NET MVC 4 project by nuget package.
https://github.com/Antaris/RazorEngine

I fixed this problem by remove following part from web.config
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Razor" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
      </dependentAssembly>

Reason:
Default ASP.NET MVC 4 razor engine is version 2, and nuget for RazorEngine project is version 3.

Coding Explained in 25 Profound Comics

https://medium.com/@FreeCodeCamp/coding-explained-in-25-profound-comics-8847ea03819c

Make hard coding your default choice

http://enterprisecraftsmanship.com/2015/06/08/make-hard-coding-your-default-choice/

To my experiences, I divide this kind of  "magic number" into three categories:

#1 Very small chance to change: Hard coding
#2 Good chance to change in the future:
  Hard coding with default value but checking config file first
string ConfigSetting_SMTP_host = ConfigurationManager.AppSettings["SMTP_host"] ?? "google.com";

#3 For sure change (such as dev vs product environment): read from config file directly

How to solve Access is denied problem for a ASP.NET MVC 4 Windows Authentication project

Create a ASP.NET MVC 4 intranet project, and run, get following error:

Access is denied
Description: An error occurred while accessing the resources required to serve this request. The server may not be configured for access to the requested URL.
Error message 401.2.: Unauthorized: Logon failed due to server configuration.  Verify that you have permission to view this directory or page based on the credentials you
supplied and the authentication methods enabled on the Web server.  Contact the Web server's administrator for additional assistance.


Solution:
Press F4 to get project property windows:
Change Anonymous to Disabled
Change Windows Authentication to Enabled.


(Why just publish a correct project template for Windows Authentication in the first place?)

Static Code Analysis Tool in Visual Studio 2013

http://blogs.msdn.com/b/hkamel/archive/2013/10/24/visual-studio-2013-static-code-analysis-in-depth-what-when-and-how.aspx

CQRS and Event Sourcing example : USING LOGS TO BUILD A SOLID DATA INFRASTRUCTURE

USING LOGS TO BUILD A SOLID DATA INFRASTRUCTURE
http://blog.confluent.io/2015/05/27/using-logs-to-build-a-solid-data-infrastructure-or-why-dual-writes-are-a-bad-idea/

Naming Java Classes Without a 'Manager'

http://www.bright-green.com/blog/2003_02_25/naming_java_classes_without_a.html

Three great virtues of a programmer; Laziness, Impatience and Hubris

http://threevirtues.com/

How to solve problem: System.IO.FileLoadException was unhandled by user code HResult=-2146234304?

Solution:
Make sure you get latest version WebGrease 1.6

Full error message:
System.IO.FileLoadException was unhandled by user code   HResult=-2146234304
  Message=Could not load file or assembly 'WebGrease, Version=1.5.1.25624, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
  Source=System.Web.Optimization
  FileName=WebGrease, Version=1.5.1.25624, Culture=neutral, PublicKeyToken=31bf3856ad364e35
  FusionLog==== Pre-bind state information ===
LOG: DisplayName = WebGrease, Version=1.5.1.25624, Culture=neutral, PublicKeyToken=31bf3856ad364e35
 (Fully-specified)



Reference:
Install-Package Microsoft.AspNet.Web.Optimization
Update-Package WebGrease
Uninstall-Package Microsoft.AspNet.Web.Optimization
Uninstall-Package WebGrease
Install-Package Microsoft.AspNet.Web.Optimization
Update-Package WebGrease
http://forums.asp.net/t/1939632.aspx?cannot+load+webgrease+due+to+mismatched+manifest

How to fix ASP.NET MVC Bundle not working (not rendering script files)

To my case, it is because System.Web.Optimization  is version 1.0.0
After getting the latest version (1.3), everything is fine

How to fix "The target GatherAllFilesToPublish does not exist"

By adding following section into Project file:

<Target Name="GatherAllFilesToPublish">
</Target>

How to apply i18n to support multiple languages in ASP.NET MVC?

For ASP.NET MVC part: Functions to switch language and get resource by culture:
http://www.codeproject.com/Articles/262917/i-n-globalization-with-gettext-and-asp-net-mvc
javascript -> cookie -> Base Controller/Razor view base page -> i18n lib functions

http://gnuwin32.sourceforge.net/packages/gettext.htm

How to edit PO files
#1 Online editor: edit, add, and delete etc.
https://localise.biz/free/poeditor
#2 Local open source app
http://sourceforge.net/projects/betterpoeditor/

C# Safe Navigation Operator ?.

Read code to understand:

var g1 = parent?.child?.child?.child;
if (g1 != null) // TODO


http://blogs.msdn.com/b/jerrynixon/archive/2014/02/26/at-last-c-is-getting-sometimes-called-the-safe-navigation-operator.aspx

Five programming problems every Software Engineer should be able to solve in less than 1 hour

https://blog.svpino.com/2015/05/07/five-programming-problems-every-software-engineer-should-be-able-to-solve-in-less-than-1-hour

How to solve problem "The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at"

To my case:
The password is wrong.

var client = new SmtpClient("smtp.gmail.com", 587)
            {
                Credentials = new NetworkCredential("myusername@gmail.com", "mypwd"),
                EnableSsl = true
            };
            client.Send("myusername@gmail.com", "myusername@gmail.com", "test", "testbody");

The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at

New Features in ASP.NET 2015 or ASP.NET 5

http://www.c-sharpcorner.com/Blogs/48460/new-features-in-Asp-Net-2015-or-Asp-Net-5.aspx

SQLBolt, interactive lessons to learn SQL in browser

http://sqlbolt.com/
Welcome to SQLBolt, a series of interactive lessons and exercises designed to help you quickly learn SQL right in your browser

Why PostgreSQL is way, way better than MS SQL Server

http://www.pg-versus-ms.com/

How good is your C#?

http://volatileread.com/Wiki?id=1073

How to solve problem "Unable to load the specified metadata resource." in Entity Framework?

Replace EDMX connection metadata part to
connectionString="metadata=res://*/;

How to create a SFTP server on the fly for unit test?\

Usage:
NuaneSFTPServer server = new NuaneSFTPServer("username", "Passw0rd!", SftpRootFolder, 990);
server.Start();

server.Stop();

    public class NuaneSFTPServer
    {
        volatile SftpServer sFTPserver = null;
        public string UserName;
        public string Password;
        public string FtpPath;
        public int PortNumber;
        private static Thread workerThread;

        public NuaneSFTPServer(string userName, string password, string ftpPath, int portNumber)
        {
            UserName = userName;
            Password = password;
            FtpPath = ftpPath;
            PortNumber = portNumber;
            SshKey rsaKey = SshKey.Generate(SshKeyAlgorithm.RSA, 1024);
            SshKey dssKey = SshKey.Generate(SshKeyAlgorithm.DSS, 1024);

            // add keys, bindings and users
            sFTPserver = new SftpServer();
            sFTPserver.Log = Console.Out;
            sFTPserver.Keys.Add(rsaKey);
            sFTPserver.Keys.Add(dssKey);
            sFTPserver.Bindings.Add(IPAddress.Any, portNumber);
            sFTPserver.Users.Add(new SshUser(userName, password, ftpPath));
        }
        public void Start()
        {
            workerThread = new Thread(sFTPserver.Start);
            workerThread.Start();
            while (!workerThread.IsAlive) ;
        }
        public void Stop()
        {
            sFTPserver.Stop();
            workerThread.Join();
        }
    }

How to fix The thread xxx has exited with code 259 (0x103)?

When try to wait for a thread to be alive, but not call thread Start method, will get a lot of errors like this::The thread xxx has exited with code 259 (0x103)

            workerThread = new Thread(StartMethod);
//            workerThread.Start();
            while (!workerThread.IsAlive) ;

:)

How would you define good code?

http://engineering.intenthq.com/2015/03/what-is-good-code-a-scientific-definition/

How to create a sub domain on the fly in IIS Server / ASP.NET project

How to create a sub domain on the fly in IIS Server / ASP.NET project

Step 1: Add following DNS records into your donmain:
example.com  IN A XXX.XXX.XXX.XXX
www.example.com  IN A XXX.XXX.XXX.XXX
default.example.com IN A XXX.XXX.XXX.XXX

# Wild card DNS record
*.example.com  IN CNAME default.example.com

Step 2: Create your website in IIS Server for default.example.com

Step 3: Get your sub domain name in ASP.NET MVC project
        var uri = Request.Url;
        var fullDomain = uri.GetComponents(UriComponents.Host, UriFormat.SafeUnescaped);
        var domainParts = fullDomain
            .Split('.') // ["test", "example", "com"]
            .Take(1);    // ["com", "example"]
        var subdomain = String.Join(".", domainParts);

DTO vs Value Object vs POCO

http://enterprisecraftsmanship.com/2015/04/13/dto-vs-value-object-vs-poco/

Architectures Comparison Summary

For Event-Driven architecture. there are two problems:
Testability and Development

But with CQRS/Event Sourcing, it is very easy to create BDD unit test.

Source:
http://www.oreilly.com/programming/free/files/software-architecture-patterns.pdf

Complexity is the enemy

http://neugierig.org/software/blog/2011/04/complexity.html

Excerpt:

"Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it."

John Resig, source code comments on jQuery

http://genius.it/5088554/ejohn.org/files/jquery-original.html
The original JQuery Source code, led by John Resig, inventor of jQuery

Developer survey 2015

http://stackoverflow.com/research/developer-survey-2015

Saga basic concept and unit test reference list

In DDD/CQRS, A saga is a “long-lived business transaction or process between aggregates”, also call process manager

http://blog.jonathanoliver.com/cqrs-sagas-with-event-sourcing-part-i-of-ii/
http://blog.jonathanoliver.com/cqrs-sagas-with-event-sourcing-part-ii-of-ii/
How to unit test saga
http://www.udidahan.com/2008/02/04/sagas-and-unit-testing-business-process-verification-made-easy/
http://docs.particular.net/nservicebus/sagas/

How much code coverage do you really need?

http://software-development-thoughts.blogspot.ca/2011/04/how-much-code-coverage-do-you-really.html

Two quotes from Uncle Bob
“Two things. Repeatability and cost. Manual tests are horrifically expensive compared to automated tests.”

“Manual tests aren't tests; they are trials. And since there are humans involved, they are suspect."

Tree of programming languages

http://commons.wikimedia.org/wiki/File:Genealogical_tree_of_programming_languages.svg

Last line effect

We expose the “last line effect,” the phenomenon that the last line or statement in a micro-clone is much more likely to contain an error than the previous lines or statements. We do this by analyzing 208 open source projects and reporting on 202 faulty micro-clones.


x += o t h e r . x ;
y += o t h e r . y ;
z += o t h e r . y ;

http://www.st.ewi.tudelft.nl/~mbeller/publications/2015_beller_zaidman_karpov_the_last_line_effect_preprint.pdf

About Command Idempotency

Definition from Gregor (New ACID)
“In the world of distributed systems, idempotency translates to the fact that an operation can be invoked repeatedly without changing the result.”

http://www.eaipatterns.com/ramblings/68_acid.html
http://codebetter.com/gregyoung/2010/08/12/idempotency-vs-distibuted-transactions/

Idempotency Patterns
http://blog.jonathanoliver.com/idempotency-patterns/

What is the exact meaning of "Single" in Single responsibility principle

http://sklivvz.com/posts/i-dont-love-the-single-responsibility-principle
I don't love the single responsibility principle

How to deal with communication between aggregate roots?

http://danielwhittaker.me/2014/11/22/4-secrets-inter-aggregate-communication-event-sourced-system/

What is Event-driven architecture?

Behind Event-driven architecture, system model is treated as a state machine. After a command changed the state, an event is generated to notify other components.
http://c2.com/cgi/wiki?EventDrivenArchitecture

What is a simple explanation of higher order functions and callbacks in JavaScript?

http://www.quora.com/What-is-a-simple-explanation-of-higher-order-functions-and-callbacks-in-JavaScript

var animals = [

  { name: 'Waffles',  type: 'dog', age: 12 },

  { name: 'Fluffy',   type: 'cat', age: 14 },

  { name: 'Spelunky', type: 'dog', age: 4 },

  { name: 'Hank',     type: 'dog', age: 11 },

];

var oldDogs = animals.filter(function(animal) {

  return animal.age > 10 && animal.type === 'dog';

});

What is category in Event Store?

 If put dash into stream name, the first part will be saved as category name

Source code from Event Store 

  _handler = new CategorizeEventsByStreamPath("-", Console.WriteLine);

        public override string GetCategoryByStreamId(string streamId)
        {
            string category = null;
            if (!streamId.StartsWith("$"))
            {
                var lastSeparatorPosition = streamId.IndexOf(_separator);
                if (lastSeparatorPosition > 0)
                    category = streamId.Substring(0, lastSeparatorPosition);
            }
            return category;

        }



http://codeofrob.com/entries/creating-a-projection-per-stream-in-the-eventstore.html

How to add Multiple Regular Expression Validation attribute into one Property in ASP.Net MVC?

Create another new attribute and inherit from RegularExpressionAttribute

    public class RegularExpressionAttribute : ValidationAttribute
    {
        private string _pattern;
        public RegularExpressionAttribute(string pattern)
        {
            _pattern = pattern;
        }
        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        {
            if (value == null) return null;
            if (!System.Text.RegularExpressions.Regex.IsMatch(value.ToString(), _pattern))
            {
                return new ValidationResult(FormatErrorMessage(validationContext.DisplayName));
            }
            return null;
        }

    public class RegularExpression2ndAttribute : RegularExpressionAttribute {}


So in view model:
        [ValidURL(ErrorMessage = "Invalid URL")]
        [RegularExpression(@"^.*\.(jpg|JPG|gif|GIF|jpeg)$", ErrorMessage = "Not a image URL")]
        public string LogoUrl { get; set; }

Why Libraries are better than Frameworks

http://tom.lokhorst.eu/2010/09/why-libraries-are-better-than-frameworks?repost=yes

CamelCase vs underscores

https://whathecode.wordpress.com/2011/02/10/camelcase-vs-underscores-scientific-showdown/

What is unit of work and relationship with CQRS/Event Sourcing?

See
http://martinfowler.com/eaaCatalog/unitOfWork.html

But I think this pattern is not applicable for CQRS/Event Sourcing, because SAGA is the way to deal with transaction in CQRS/Event Sourcing.
Reference:
https://msdn.microsoft.com/en-us/library/jj591569.aspx

What is Aggregate in DDD?

From Eric Evans book DDD Page 90
An AGGREGATE is a cluster of associated objects that we treat as a unit for the purpose of data changes. Each AGGREGATE has a root and a boundary. The boundary defines what is inside the AGGREGATE. The root is a single specific ENTITY contained in the AGGREGATE. The root is the only member of the AGGREGATE that outside objects are allowed to hold references to, although objects within the boundary may hold references to each other. ENTITIES other than the root have local identity, but it only needs to be unique within the aggregate, since no outside object can ever see it out of the context of the root ENTITY.

By Martin Fowler
a cluster of domain objects that can be treated as a single unit.
http://martinfowler.com/bliki/DDD_Aggregate.html

ASP.NET 5

http://weblogs.asp.net/scottgu/introducing-asp-net-5

How to enable intellisense in Visual Studio after remove reSharper?

My Visual Studio inellisense stopped working after removed ReSharper(ReSharper is so slow).

The solution:
Tools->Options->Text Editor->All Languages->General
Turn off "Auto list members", and "Parameter information"
And turn on again.

How to get stream name list from Event Store?

Better idea from Greg Young

Greg Young <gregoryyoung1@gmail.com>	Feb 20 (3 days ago)
to event-store

$streams? https://github.com/EventStore/EventStore/blob/dev/src/EventStore.Projections.Core/Standard/IndexStreams.cs is the internal projection code. It must be enabled.

What will happe  to your projection with 100m streams?

Original test code:

fromAll().
    when({
        $init: function(s,e) { return {streanList:"", count:0} },
        $any : function(s,e) {
            if (!s.streanList){
                s.streanList =" ";
            }
            if (s.streanList.indexOf(e.streamId) < 0){
               s.streanList = s.streanList + e.streamId +",";
               s.count++;
            }
        }
    })

Reference:
http://dbs-are-fn.com/2013/interview_greg_young_event_store/

How to count event number in one stream?

fromStream("streamName")
   .when({
        $init: function() {
           return { count: 0 }
        },
        $any : function(s,e) { return s + 1;}
  })

How to count event number in Event Store?

fromAll().
    when({
        $init: function(s,e) { return 0;},
        $any : function(s,e) { return s + 1;}
    })

How to solve problem: customized projection is not running in Event Store

The defualt setting is  --run-projections=SYSTEM
Need to change
--run-projections=ALL

Reference:
https://github.com/EventStore/EventStore/wiki/Command-Line-Arguments

Refactoring code that accesses external services by Martin Fowler

http://martinfowler.com/articles/refactoring-external-service.html

How to solve problem "Read access denied for stream" while reading events from event store?

Get this error on following line:
var event = connection.ReadStreamEventsForwardAsync(streamid, 0, 1, false).Result;

Need to add credential for reading
var event = connection.ReadStreamEventsForwardAsync(streamid, 0, 1, false,  new UserCredentials("admin", "changeit")).Result;

How to solve problem "System.AggregateException: One or more errors occured ---> EventStore.ClientAPI.Exceptions.RetriesLimitReachedException" when try to connect to write event to Event Store?

This error happened  after downloaded Event Store 3.0.1 and tried following code for the testing

            string serverIpaddress = "127.0.0.1";
            var connection = EventStoreConnection.Create(new IPEndPoint(IPAddress.Parse(serverIpaddress), 2113));
            connection.ConnectAsync().Wait();
            var myEvent = new EventData(Guid.NewGuid(), "testEvent", false,
                                        Encoding.UTF8.GetBytes("some data1"),
                                        Encoding.UTF8.GetBytes("some metadata"));
            connection.AppendToStreamAsync("test-stream",
                               ExpectedVersion.Any, myEvent).Wait();

On line of AppendToStreamAsync, exception throws:
 "System.AggregateException: One or more errors occured ---> EventStore.ClientAPI.Exceptions.RetriesLimitReachedException"

Cause: .NET API of Event Store goes by TCP port, which default value is 1113, http port number is 2113 by default.

Just change to            
          var connection = EventStoreConnection.Create(new IPEndPoint(IPAddress.Parse(serverIpaddress), 1113));

Reference
https://groups.google.com/forum/#!topic/event-store/5uWEqybibw8

How to check TcpListener is listening?

In TcpListener class, there is a property called Active but it a proctected one.
https://msdn.microsoft.com/en-us/library/system.net.sockets.tcplistener.active(v=vs.110).aspx

Solution:
Create a sub class from TcpListener, and expose this property by yourself.

Code example:
    public class Listener : TcpListener
    {
        public Listener(int portNumber): base(IPAddress.Any, portNumber) {}
        public bool IsAcitve
        {
            get { return this.Active; }
        }
    }

What is projection in event sourcing

Projection is about deriving current state from the stream of events
Reference:
http://abdullin.com/post/event-sourcing-projections/

Quote from Ralph Johnson: Before software can be reusable it first has to be usable.

Reusable software is not number one priority anymore. So why want to design software to be reusable.

Reading about CQRS and event souring

Exploring CQRS and Event Sourcing
https://msdn.microsoft.com/en-us/library/jj554200.aspx

Applying CQRS and Event Sourcing in Microsoft .NET Applications TechEd Europe 2014
https://www.youtube.com/watch?v=z5FPkCgcH4M

What is bounded context?

From DDD website:
[[Bounded Context]] The delimited applicability of a particular model. BOUNDING CONTEXTS gives team members a clear and shared understanding of what has to be consistent and what can develop independently.
http://dddcommunity.org/resources/ddd_terms/

From Martin Folwer:
Bounded Context is a central pattern in Domain-Driven Design. It is the focus of DDD's strategic design section which is all about dealing with large models and teams. DDD deals with large models by dividing them into different Bounded Contexts and being explicit about their interrelationships.
http://martinfowler.com/bliki/BoundedContext.html

From MSDN
The term bounded context comes from Eric Evans' book. In brief, Evans introduces this concept as a way to decompose a large, complex system into more manageable pieces; a large system is composed of multiple bounded contexts. Each bounded context is the context for its own self-contained domain model, and has its own ubiquitous language. You can also view a bounded context as an autonomous business component defining clear consistency boundaries: one bounded context typically communicates with another bounded context by raising events.
https://msdn.microsoft.com/en-us/library/jj591575.aspx

From "DDD: The Bounded Context Explained"
http://www.sapiensworks.com/blog/post/2012/04/17/DDD-The-Bounded-Context-Explained.aspx

really Explained?

Same question at
http://programmers.stackexchange.com/questions/237513/what-in-reference-to-ddd-is-a-bounded-context

Conclusion:  bounded context is a fence.

How come a key concept in DDD is with so many ambiguous definitions?
:)

Procedural vs OO, Anthropomorphism Gone Wrong: Poor Motivating Example for OOP

Procedural vs OO with code example
http://loup-vaillant.fr/articles/anthropomorphism-and-oop

How to solve Visual Studio git push problem "You cannot publish local branch master to the remote repository origin"?

Error happened:
When I created a local git repository and tried to push to remote repository, got following error:

"You cannot publish local branch master to the remote repository origin because a branch with the same name already exists there. You might want to rename your local branch and try again"

Solution:
- Install 3rd party git tool
- Add remote repository in GitUI
- Click push, and select "remote repository"

How much do you pay per line of code?

http://www.yegor256.com/2014/04/11/cost-of-loc.html

Service Locator vs. Dependency Injection

Includes C# code examples to compare two pattern.
https://software2cents.wordpress.com/2013/03/30/service-locator-vs-dependency-injection/

60 Problem Solving Strategies

http://java.dzone.com/articles/60-problem-solving-strategies

What is difference between Service Locator and Dependency Injection?

From Martin Fowler
http://martinfowler.com/articles/injection.html#ServiceLocatorVsDependencyInjection

From Stackoverflow
http://stackoverflow.com/questions/1557781/whats-the-difference-between-the-dependency-injection-and-service-locator-patte

Will try to write home-made  Service Locator first to see what happen.
If any problem, will try DI containers, such Autofac

Why readonly in C#?

Make summary form following post:
http://stackoverflow.com/questions/277010/what-are-the-benefits-to-marking-a-field-as-readonly-in-c

1. Improve readability: tell how to not use in other way.
2. Nothing to do with performance
3. Immutable data structures in threading

Where "No function should be longer than what can be printed on a single sheet of paper" come from?

From NASA

http://sdtimes.com/nasas-10-rules-developing-safety-critical-code/

What is real purpose of Enable Visual Studio Hosting Process?

According to MSDN:
"The Visual Studio hosting process improves debugger performance and enables new debugger features, such as partial-trust debugging and design-time expression evaluation"

In real world:
Sometimes, vshost.exe always running, and you can't even kill it from Task Manager. (After killed it, it restores automatically, need to quit Visual Studio)

Need to disable this feature/bug by following steps:
Properties of project =>
"Debug" tab =>
uncheck "Enable the Visual Studio hosting process"

How to solve in C++ upgraded project for error LNK2001: unresolved external symbol "?.cctor@@$$FYMXXZ" (?.cctor@@$$FYMXXZ)?

Remove /Zl from Configuration Properties -> C/C++ -> All Options -> Additional Options

TDD is about Development not Design

TDD is about Development not Design

In initial design stage, need to hide unrelated detail as much as possible, cover high level scenario only.

Test Driven Design forces thinking on low level details. In this way, it is very easy to lose focus.


Try a new project to see if TDD stands for Test Driven Development, or Test Driven Design

Why I Don't Teach SOLID

"The main culprit is SOLID's focus on dependencies. "
"These all lead developers to create interfaces everywhere.  They litter the codebase with interfaces like IFooer, IDoer, IMooer, and IPooer.  Navigating it becomes a nightmare. "
http://qualityisspeed.blogspot.nl/2014/08/why-i-dont-teach-solid.html



Personal experience:
I ever worked on a similar project:  this project has two functions: a wrapper for Icewarp API to create/update email accounts.
3k line of codes, near 10 layers of interface. Indeed, it is "SOLID" :)

How to fix FakeitEasy problem The current proxy generator can not intercept the specified method for the following reason: Sealed methods can not be intercepted.

Add virtual keyword to the method
http://geekswithblogs.net/Aligned/archive/2013/03/12/fakeiteasy---sealed-methods-can-not-be-intercepted-exception.aspx

TDD Is About Design, Not Testing

"Writing tests after writing code is a corruption of TDD"
"The act of writing a unit test is more an act of design than of verification."
http://www.drdobbs.com/tdd-is-about-design-not-testing/229218691

TDD is a way to design software? or a way to verify/refine design? or both?

How to solve problem: Installed Windows service by installutil not showing up in MMC services windows

Although installutil tells you everything is fine, the new service will not show up in MMC services windows.
Solution: use sc
sc create servicename binPath= servicebin.exe

Readonly vs const in C#

A const field can only be initialized at the declaration of the field.
A readonly field can be initialized either at the declaration or in a constructor

http://msdn.microsoft.com/en-us/library/vstudio/acdd6hb7(v=vs.100).aspx

What is "Architectural Spike"?

An architectural spike is a thin slice of the entire application built for the purpose of determining and testing a potential architecture.

Definition from:
https://groups.yahoo.com/neo/groups/extremeprogramming/conversations/topics/18232

The most difficult part of TDD: You have to write tests first before coding/design/implementation

"Have to actually think what you expect from a piece of code BEFORE you write it! Madness! Instead of just writing code, you have to think before you code! And if you can't formulate properly an expectation, HOW do you write the code in the first place?!"

http://www.sapiensworks.com/blog/post/2013/07/17/-TDD-Is-Not-Slow.aspx

CQRS, Command Query Responsibility Segregation FAQ

CQRS by Martin Fowler
http://martinfowler.com/bliki/CQRS.html

Introducing the Command Query Responsibility Segregation Pattern from MSDN
http://msdn.microsoft.com/en-us/library/jj591573.aspx

C# code exmaple: LIntroduction to CQRS
http://www.codeproject.com/Articles/555855/Introduction-to-CQRS

One Hacker Way, a Rational Alternative to Agile

http://vimeo.com/110554082

Reusable Software? Just Don't Write Generic Code

http://josdejong.com/blog/2015/01/06/code-reuse/