Skip to main content

Sistem stateless si sisteme stateful

Citeam un articol ce descria paraller programing. Si am ajuns la doi termeni care desi imi pareau cunoscuti nu imi erau foarte clar definiti.
Cei doi termeni sunt
  • stateless system;
  • stateful system;
Un sistem stateless este un sistem inchis, unde output-ul depinde doar de input si atata. Rezultatul obtinut nu este deloc influentat deloc de alte valori pe care sistemul le poate stoca intr-o forma sau alta.
In cazul acesta un exemplu ar putea sa fie:
Oriunde pe glob ne-am afla si orice setare am aveam la masina( regional settings), valoarea returnata o sa fie aceiasi in orice locatie de pe glob. Acest sistem poate sa fie numit stateless din punct de vedere a regional settings.
Un sistem stateful este un sistem deschis, unde outpu-ul nu depinde doar de input. Pentru calcularea output-ului se i-au in considerare si alte valori. Poate fi vazut intr-o oarecare masura ca o masina de stari, care poate sa isi pastreze ultima stare.
Un bun exemplu este:
In functie de regional settings, o sa putem avea valori diferite afisate in zone diferite ale lumii, deoarece propietatea statica Now tine cont de regional settings.
Din punct de vedere a rularii in paralel, un sistem stateless este cel mai usor de implementat. Oricate thread-uri ar exista, acestea nu trebe sa partajeze/sincronizeze informatii. Fiecare isi poate face treaba cu input-ul pe care il are.
In cazul unui sistem stateful, programarea in paralel nu mai este atat de simpla. Pot sa apara cazuri cand mai multe resurse( stari ale masinii sau sistemului) sunt partajate intre mai multe theaduri, caz in care apare lucrurile se complica.


Popular posts from this blog

How to check in AngularJS if a service was register or not

There are cases when you need to check in a service or a controller was register in AngularJS.
For example a valid use case is when you have the same implementation running on multiple application. In this case, you may want to intercept the HTTP provider and add a custom step there. This step don’t needs to run on all the application, only in the one where the service exist and register.
A solution for this case would be to have a flag in the configuration that specify this. In the core you would have an IF that would check the value of this flag.
Another solution is to check if a specific service was register in AngularJS or not. If the service was register that you would execute your own logic.
To check if a service was register or not in AngularJS container you need to call the ‘has’ method of ‘inhector’. It will return TRUE if the service was register.
if ($injector.has('httpInterceptorService')) { $httpProvider.interceptors.push('httpInterceptorService&#…

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine:
threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration:

TeamCity.NET 4.51EF 6.0.2VS2013
It seems that there …

Run native .NET application in Docker (.NET Framework 4.6.2)

The main scope of this post is to see how we can run a legacy application written in .NET Framework in Docker.

First of all, let’s define what is a legacy application in our context. By a legacy application we understand an application that runs .NET Framework 3.5 or higher in a production environment where we don’t have any more the people or documentation that would help us to understand what is happening behind the scene.
In this scenarios, you might want to migrate the current solution from a standard environment to Docker. There are many advantages for such a migration, like:

Continuous DeploymentTestingIsolationSecurity at container levelVersioning ControlEnvironment Standardization
Until now, we didn’t had the possibility to run a .NET application in Docker. With .NET Core, there was support for .NET Core in Docker, but migration from a full .NET framework to .NET Core can be costly and even impossible. Not only because of lack of features, but also because once you…