WS-Knowledge

I love Coffee & I like CoffeeScript :)

 

* CoffeeScript is a little language that compiles into  JavaScript. * CoffeeScript is an attempt to expose the good parts of JavaScript in a simple way. * The golden rule of CoffeeScript is: "It's just JavaScript". -- from the official site

Just recently I heard fellows on Twitter talking about CoffeeScript. I believe I heard the name before but I was very busy couldn’t even have a look. This time I tried to check what is that.

It turns out to be a new way for writing JavaScript that is more compact & dynamic, and resembles Ruby and Python dynamic languages. After I gave it few hours & I felt I like it.

The idea behind this new language is to write your code in a dynamic syntax that later can be compiled to generate a 100% equivalent JavaScript that's granted to be always valid if you check it against a tool like JavaScript Lint. The gain of this is brevity and readability, typically 1/3 fewer lines with no effect on runtime performance.

First issue I faced was how to get it working on my PC? The installation on Windows is somehow long & complex; no single-filre installer available for Windows on the official site yet. But I found this project that simplifies compiling CoffeeScript into JavaScript on Windows. Hence, my first environment consisted of a good text editor, Notepad++, and a CoffeeScript Compiler for Windows. There's another simple alternative, the online compiler available on official site called "TRY COFFEESCRIPT".

What I liked about this language that I can write complex JavaScript in a more compact & readable form. The major difference for me, since that I’m not a good JavaScript developer, I don’t like the way JavaScript define classes. JavaScript way of defining classes sounds, for me, a method-oriented way than an object-oriented way. But when tried CoffeeScript I was able to express my thoughts in an object-oriented way. Moreover, It has a dynamic syntax similar to Ruby & Python that takes indentation into account instead of braces and parentheses to make your code looks more readable & expressive; though I love static languages in general & specifically C# :)

Using my simple environment, I managed to write my first simple program. I found Ayende’s latest challenge for Tax Calculation a good start, so I decided to write my answer in CoffeeScript. You can find this simple program in this GitHub:Gist. The screenshot below can give u an idea about how does it look like if u didn’t check the official site yet.

 

This is my first account about CoffeeScript, the second will come soon about preparing a better environment for developing on Windows, probably also on Ubuntu.

Enjoy learning... :)

Building a stand-alone Windows service on top of Topshelf

I'd like to share my experience about a valuable OSS project I liked very much & used recently.
The latest project I designed & implemented was an integration subsystem that acts as a bridge between two systems, our B2C Portal & e-Government  Message-based Services.

The solution architecture is based on building multiple multi-threaded windows services that receive, parse, initiate and send different types of requests & transactions between both systems bidirectional.
Building this number of windows services required building a good common infrastructure for all services to make them consistent enough, well refactored, and easy to debug.
And, Here came the decision to use Topshelf as an infrastructure for my services. Topshelf describes itself as "An easy service hosting framework for building Windows services using .NET"

What I liked about Topshelf, as a first reason to search about it & use it, that It enables you to build Windows service as a console application and run & debug it as a console application but you can deploy it as a Windows service. This idea sounds very good for me. So my services shouldn’t inherit from a specific class and shouldn't install them during development time before each debug session & uninstall them again.

Edit: Installing Topshelf became quite easy because of NuGet integration with Visual Studio 2010.
Other wise, you can simply download binaries & add references to you project.

So, let's see how it's easy to use Topshelf! All what I need is an empty console application and in the main method let's write the following.

   1: const string SERVICE_NAME = "Do Something Service";

   2:  

   3: // configure log4net

   4: XmlConfigurator.Configure(PathHelper.GetFileInfo("do_something_service.log4net"));

   5:  

   6: // configure service runner or host

   7: HostFactory.Run(cfg => {

   8:     cfg.Service<IDoSomethingService>(svc => {

   9:         svc.SetServiceName(SERVICE_NAME);

  10:         svc.ConstructUsing(name => new DoSomethingService());

  11:         svc.WhenStarted(service => service.Start());

  12:         svc.WhenStopped(service => service.Stop());

  13:     }); cfg.RunAsLocalSystem();

  14:     cfg.SetDescription(SERVICE_NAME);

  15:     cfg.SetDisplayName(SERVICE_NAME);

  16:     cfg.SetServiceName(SERVICE_NAME);

  17: });

Those few lines will make the console application work both as console application, as expected, and also as a Windows service that can be installed & controlled from Services Manager.

The code shown above is very generic so it doesn’t require implementing specific interfaces or to inherit from specific base classes. You can see method signatures below to make sure it’s all generic.

   1: void ConstructUsing(Topshelf.Model.DescriptionServiceFactory<TService> serviceFactory);

   2: void WhenStarted(System.Action<TService> startAction);

   3: void WhenStopped(System.Action<TService> stopAction);

To implement my services, first, I created custom interfaces. First interface called IGenericService that will be a base for all service classes. Then, I create a custom interface for each service. For instance, I create DoSomethingService, I use an interface IDoSomethingService that inherits from IGenericService.

   1: public interface IGenericService {

   2:     void Start();

   3:     void Stop();

   4: }

   5:  

   6: public interface IDoSomethingService : IGenericService {

   7: }

   8:  

   9: public class DoSomethingService : IDoSomethingService {

  10:     void Start() { return; }

  11:     void Stop(){ return; }

  12: }

Now, you can easily install your console application executable as a Windows service through the following command line: {console_exe} install  Or {console_exe} uninstall to uninstall it.
Then, using Services Manager you can control the service as needed.

There’s another way to host services built by Topshelf called shelving but I was interested in stand-alone Windows services that I can control through Services Manager.

That was a quick dumb of steps I went through during building my services. I hope it was useful.
Questions are welcome :)

Looking to Clouds!

Few days ago, I started looking to Clouds! Though, they were there for a while now, but I have been very busy looking down to duties I have. Before, I read about about Cloud Computing, Software as a Service, SaaS, Platform as a Service, PaaS, and Infrastructure as a Service, IaaS, but when I saw Window Azure, I felt this is different than what I imagined.

I started collecting more data about Window Azure and I found a nice series on Channel 9, called Cloud Cover Show, which covers news, features, and tips about Windows Azure. I decided to dedicate more time to try different aspects of Azure, so I have installed Windows Azure SDK 1.2.

Today, I found Heroku, (pronounced her-OH-koo) is a cloud application platform for Ruby, as wrote on their site. I can find a similarity between anatomy of their structure & anatomy of Windows Azure in a way it adds to the whole picture in mind. Also, considering Google's AppEngine, I think this will give us a colorful sky with variety of clouds to host different kinds of applications :)
But, I think this is only conceptually, since that for all applications based on .Net Framework & Microsoft technologies the only option is Windows Azure, which's a great option but still the only one too.

The only sad news for me was that I couldn't open an Introductory Account because because of geographical obstacles. Currently, I live in Saudi Arabia and I couldn't find it on the list of Countries to choose. Also, Egypt, my home country, isn't available on the list too. I hope to find a solution soon.
In the mean time, I will study the subject locally on development fabric.

Puzzling Questions:

• Will future be heavily heading towards Cloud-based development? 
• Will on-premise hosting come to end in future?
• Will few Giant companies, like Microsoft & Google, dominate Cloud-based hosting? Is not this involves considerable risks?
• How will competition take place in future on the light of cloud-based applications/hosting?

Well, that was all in my mind till now, a newbie point of view :)

More elaboration on Windows Azure is expected as soon as I start a bet project.

Contracts or Validation?!

Recently, I came across FluentValidation, a validation framework created by Jeremy Skinner. I browsed the code base & It's very interesting & reflects a great effort. I think I'll learn a lot from it in the future. So, I decided to make a change for a hobby project I'm working on.
In my hobby project, Entities use a simple Design by Contracts, DbC, for validating method inputs. 

I had a test like this

 1: [Test]

 2: public void Cannot_create_account_with_null_name()

 3: {

 4:  string name = null;

 5:  string description = "Account Description";

 6:  decimal openingBalance = 2500m;

 7:  

 8:  var exception = Assert.Throws<PreconditionException>(()

 9:   => new Account(name, description, openingBalance));

 10:  

 11:  Assert.AreEqual(exception.Message, SystemMessages.Errors.ValueIsRequired("name"));

 12: }

That tests a constructor like this

 1: public Account(string name, string description, decimal openingBalance)

 2: {

 3:  Check.Require(name.IsNotEmpty(), 

 4:      SystemMessages.Errors.ValueIsRequired("name"));

 5:  Check.Require(openingBalance >= 0, 

 6:      SystemMessages.Errors.OpeningBalanceMustBeGreaterThanZero);

 7:  

 8:  Id = Guid.NewGuid();

 9:  Name = name;

 10:  Description = description;

 11:  OpeningBalance = openingBalance;

 12:  CurrentBalance = openingBalance;

 13: }

I thought to change the test to be like this

 1: [Test]

 2: public void Cannot_create_account_with_null_name()

 3: {

 4:  string name = null;

 5:  string description = "Account Description";

 6:  decimal openingBalance = 2500m;

 7:  

 8:  var account = new Account(name, description, openingBalance);

 9:  var result = validator.Validate(account);

 10:  

 11:  Assert.IsFalse(result.IsValid);

 12:  Assert.AreEqual(1, result.Errors.Count);

 13: }

And to create a validator for the Account entity like this

 1: using FluentValidation;

 2:  

 3: public class AccountValidator : AbstractValidator<Account>

 4: {

 5:  public AccountValidator()

 6:  {

 7:   RuleFor(account => account.Id).NotEmpty();

 8:  

 9:   RuleFor(account => account.Name).NotEmpty();

 10:  

 11:   RuleFor(account => account.OpeningBalance)

 12:    .GreaterThanOrEqualTo(0)

 13:    .WithMessage(SystemMessages.Errors.OpeningBalanceMustBeGreaterThanZero);

 14:  

 15:   RuleFor(account => account.CurrentBalance)

 16:    .GreaterThanOrEqualTo(0)

 17:    .WithMessage(SystemMessages.Errors.CurrentBalanceMustBeGreaterThanZero);

 18:  }

 19: }

But writing this change, I found it doesn't sound logic. What if the user of this entity didn’t run the validation?! the entity still can be created with invalid arguments which shouldn't happen.

That led me to the question about Contracts against Validation?
The problem is not in the validation framework but I think it’s in the way I used it.
So, I checked some of available examples over the Internet but I found them do the same.

Since that I didn't reach an answer yet, I decided to leave this post openly ended & I hope to receive recommendations or comments about what is the best practice here. When and Where to use, or not to use, Validation and/or Contracts. By `Where` I means in which layer of solution should we use Validation and/or Contracts to reflect different business rules.

ORM & ME, story I like to share

It has been a journey so I’ll try to emphasis only the important stopovers and turnovers I passed by.
Back in 2005, I was still new to .NET but with good professional & unprofessional experience with many different other languages.  I started like everyone and I say like everyone because I found that there's a path that unintentionally many follow it step by step. May be some was faster than others & some stopped & didn’t continue. This path represented a natural evolving path of ideas & techniques for me & many others.

I started from reading about Data Access Layers & how to build a DAL in a layered application architecture.
So, I started to search for a better way to do it. I built my first, and last, DAL framework and called it "EntityDAC".
It was based on an abstract base class I called EntityDAC that every DAC object, or DAO,  inherits from in order to do basic CRUD operations on a certain table. I used this in a project then I found things getting more complex. The major shortcoming was due to inflexibility in querying. So, I started to look around for a better solution. Here, I read a remarkable statement that meant for me that I shouldn’t re-invent the wheel, there are others who already wrote Data Access frameworks & probably did it better & mature now. But, I think taking chance to write first trial by myself was important later to enable me to choose between different frameworks.

I found some tools that can generate classes from database directly. It was a great discovery at this time better than code generator that generate stored procedures & helper classes to call these procedures.  But later I started to face troubles of re-generating those classes when I change my database. Then, I read about Persistence & the use of Persistence Layer instead of Data Access Layer. That was brilliant, Persistence layer was the most attractive concept I read at that time and still correct & valid till the date. It's a shift from what we used to called Data-Driven applications to real Object-Oriented applications. Persistence, from my humble point of view, It’s a thin layer that enables my domain entities & services to persist their state to database when needed. Why this is brilliant? We need to look from the right angle. First, my application mainly consists of Objects that represents Entities in problem domain. Interaction between these objects represents the application functionality. Storing results of these interactions is an optional issue not the major issue. In other words, not every application is Data-Driven application, but every Data-Driven application is an application (has functionalities, responsibilities & calculations). For example, Let’s say my client needs an Online Shopping application that sends the Site Admin or Shipping Officer an email when a new Customer submits a new Order, although that is stupid, that means there is no database here & application still valid & carry out its responsibilities. But If he decided to save these orders to database so he can query this information later that will require to persist the state of Customer & Order to some storage; like a database. Imagine having a thin layer that can simply perform the following.

  1: newCustomer.Save();

  2: newOrder.Save();

  3: CommitChanges(); // this is a pseudo code

That is impressive. So now you can concentrate on the real business; What are the responsibilities of these entities; Customer and Order? and what is the expected interaction between them. Persistence also is not about just database we can extend this idea to other storages, like text files, xml files or whatever  is proper as a storage.
Right, you can say that all or most of applications we write uses Relational Databases in the back-end but that should not make us think that all our job is to store some values in some rows & columns.

Even before this shift in my vision, I used to analyze problem domain carefully & try to reflect it into Objects that has proper names & responsibilities. But, at the beginning, I used to create the Data Model first then Object Model; while both models used to be very close in concept since that the origin is the same (my thoughts) :)

In the beginning of 2007, after I checked many tools & I started to distingue the ORM tools & after quick test-drives for many of them, I found NHibernate to be a great tool. Right, It’s tough to start and has a slightly high learning curve but a very decent tool. I built a simple application using It & in July 2007, I went into vacation in Egypt with my laptop & the new application. I had a plan to enjoy working on that application during vacation. First day, I opened my laptop to work on the application I found  a message that MS SQL Server Evaluation expired. It was a shock, I forgot that I have installed MS SQL 2005 – 180 days evaluation on laptop. That means that I won’t work till I reach my office again. Then, I remembered that NHibernate  is able to talk to many database engines & also it can generate schemas, but I didn’t try this before. I had MySQL on my laptop so I worked on writing a test to create the schema on MySQL, yes I used test as a tool :)
I failed first day after many many hours of work but succeeded in the next day after an hour. This application had a small suite of Unit Tests that I was reading about & trying to practice also. So, I ran tests & the surprise that everything was OK. Sure, today I understand that unit tests must not hit a database :D  Let’s say those integration tests proved that NHibernate is a great tool & I can move from a Database System to another in NO TIME.
Also, I learned that unit testing is a great tool enables you to make changes with confidence ;)

Over time, I started to change my mindset, to start thinking of Objects first & don’t think about database that early.
Later, I started to read about Domain-Drive Design I found it very close to my approach from my humble point of view. But It contains a great refinement for these concepts that I hope to master it one day soon.
I found that ORM & Domain-Driven Design are best friends. Both think in Objects.
My happiness complete after I tried Fluent NHibernate for the first time when it was a beta project. It was the missing part to make NHibernate a complete great tool. Then Linq2NH was a good complementary to that stack.
The last team player was AutoMapper that enabled me to simply return DTOs from my service layer to UI layer.
I can’t claim mastering all these technologies or techniques but I’m highly interested in them & doing my best to master them, beside others sure.

I’d like to coin some statements that I consider them keys for dealing with ORM.

1. ORM starts with O, for Objects.

2. ORM is not about to mirror database objects into programming objects, but may be the opposite.

3. ORM is not just a tool to save records in database, although It does that awesomely.

4. ORM doesn’t hurt performance & by means of caching you can build a rocket-speed application :)

I hope that was useful & wasn't too long.
Although, we can make it really useful, I like to hear from guys interested in ORM topic.

Challenge #2: Android SDK

The last two days, I have challenged myself & had a nice experience. Although, I didn't work on Java before either professionally or during college, but I challenged myself to install Android SDK & run a Hello World famous example.

First day, I've downloaded & installed all requirements. I felt strange at this time because I found myself slightly familiar. I know what is Ant because I used NAnt before & when I browse the example code I can relate every keyword to a corresponding C# equivalent so I don't feel like in enemy territory :)
But I failed to compile & run the example by the day end.

Second day, yesterday night, I went for the second round. I changed configuration & managed to compile the example & get it runs on the Emulator. It was a very happy moment.. I won the challenge :)

That encouraged me to download & install Eclipse. Although, I didn't figure out what is exactly going on behind the scenes but that encouraged me to dig deeper. I think I'll go for Round 3.

I took few screenshots of Android Emulator while playing with it which is the trigger behind this challenge. I'm puzzled about to buy iPhone, which I love, or Android Nexus One, which looks promising ;)

I hope to hear from guys interested in Mobile technology about comparisons & which's more promising.

Observation #1: Software is a Virtual World. Hence, we need a source of thoughts & metaphors.

Well, It is obvious that software development is a virtual world and here comes the continuous need for metaphors and design patterns.
A rich source of thoughts can come from experiences with real world professions and hobbies.

We all in software development know about metaphors and design patterns coming from Civil Engineering which I think is the major source of metaphors and design patterns. So, we have Software Architecture, we ‘build’ software programs and create ‘foundations’ for them. We use ‘Creational Patterns’ like ‘Factory Methods’ and ’Builder Pattern’.

The rise of Agile Software Development came from understanding that building a software, which is a virtual structure, differs from building concrete structures. The need for Big Design Upfront (BDUF) is mandatory for building concrete structures since that once you have finishes the structure foundations & moved to mounting or constructing walls your ability to change will tend to Zero. This is not the case when building a software. We can iteratively create our designs and iteratively code required features. It is true that the cost of change gets higher as time goes on. Here comes the need for extensible, flexible, and maintainable code base to enable us to adopt changes since that change is inevitable.

Therefore, although It may not sound much reasonable, I think the chance of developers who have experience with other professions or hobbies, other than computers, is higher than other fellows who owns only computer science knowledge. From this observation I started to think about the need for practicing other new hobbies, away from my computer, to the extent that I think that even fishing or carpentry can be a good source of new thoughts and experiences that can be reflected later while building a new software.

For Dear Reader: If you agree or disagree, it is valuable to hear from you. Thanks in advance.

Bad Communication = Great Waste Of Time & Resouces

This is the first time to realize this equation. I always know that Bad Communication is bad and can waste time and resources.
But, I never imagined it ca be that bad or it can cause this severe damage.

I’m leading an integration project where we are building components that consume a WCF Services hosted on a web server.
When we first receive the Integration Guide we couldn’t get in connection with services because the configuration mentioned in the documentation is totally different than the actual required configuration. That was the first communication problem that lasted for a while till we could receive a working configuration. The reason behind delay that web services owned for a company that outsourced a third-party to implement the services for it. So to reach the actual technical team you go through a tunnel of emails from us to the service owner then to the service implementor and back again through the same route.

After many trials to get things to work we agreed to make a 2-3 days workshop to solve issues face-to-face. That was after 2 months of project kick-off. It was the first time for the service implementor to hear from the real service user.
The outcome of the workshop was my recommendation of writing a proper documentation since that service implementor wasn’t ready to do any further modification and updates because for them the project is ready for sign off and we are the only impediment.

After that workshop we tried to reach the technical team again but we failed. Again, raising issues consume very long time.
After two months of the first workshop we decided to have another workshop in our location this time.
The first shocking surprise was… We are testing a different service!!! The endpoint url is different.

After this shock I realized that three companies wasted about four months of efforts and money while the major reason is `Bad Communication`. My company could not launch two products dependent on this integration project. Right there are other reason like lake of proper service interfaces although this also is part of communication in my opinion.
If they had a proper service interfaces, constructors and method signatures that would minimize the need for documentation.
Because, the service will be self-exploratory and here we can coin learned lessons for this experience.

“Bad communication = Great waste of time and resources”
“Integration is all about Interfaces”.
”Implementation Interfaces are part of project communication: developer-to-developer channel"

About Common .NET Naming Conventions

I found a great article about Common .NET Naming Conventions.
It summaries all cases with examples in a very clear way if anyone interested, like me, to be following a standard style while writing code all the time.

Long time ago I tried FxCop but unfortunately I stopped using it because of great number of warnings for missing documentation elements.

I’ve install Microsoft StyleCop version 4.3 and I'll give it a try.
Also, I need to research what is the difference between it and FxCop 3.6.

Object Oriented Software Engineering Knowledge Base

I found, by chance, this great resource. It's the first time to find such detailed information about software development stakeholders, practices, and definitions. I think I must find time to to read daily from this resource. Object Oriented Software Engineering Knowledge Base