I could use some concrete information

I'm interested in articles which have some concrete information about stateless and stateful design in programming. I'm interested because I want to learn more about it, but I really can't find any good articles about it. I've read dozens of articles on the web which vaguely discuss the subject, or they're talking about web servers and sessions - which are also 'bout stateful vs stateless, but I'm interested in stateless vs stateful design of attributes in coding. Example: I've heard that BL-classes are stateless by design, entity classes (or atleast that's what I call them - like Person(id, name, ..)) are stateful, etc.

I think it's important to know, because I believe if I can understand it, I can write better code (eg granularity in mind).

Anyways, really short, here's what I know 'bout stateful vs stateless:

Stateful (like WinForms): Stores the data for further use, but limits the scalability of an application, because it's limited by CPU or memory limits

Stateless (Like ASP.NET - although ASP tries to be stateful with ViewStates): After actions are completed, the data gets transfered, and the instance gets handed back to the thread pool (Amorphous).

As you can see, it's pretty vague and limited information (and quite focussed on server interaction), so I'd be really grateful if you could provide me with some more tasty bits of information :)

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I suggest that you start from a question in StackOverflow that discusses the advantages of stateless programming. This is more in the context of functional programming, but what you will read also applies in other programming paradigms.

Stateless programming is related to the mathematical notion of a function, which when called with the same arguments, always return the same results. This is a key concept of the functional programming paradigm and I expect that you will be able to find many relevant articles in that area.

Another area that you could research in order to gain more understanding is RESTful web services. These are by design "stateless", in contrast to other web technologies that try to somehow keep state. (In fact what you say that ASP.NET is stateless isn't correct - ASP.NET tries hard to keep state using ViewState and are definitely to be characterized as stateful. ASP.NET MVC on the other hand is a stateless technology). There are many places that discuss "statelessness" of RESTful web services (like this blog spot), but you could again start from an SO question.

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A stateful app is one that stores information about what has happened or changed since it started running. Any public info about what "mode" it is in, or how many records is has processed, or whatever, makes it stateful.

Stateless apps don't expose any of that information. They give the same response to the same request, function or method call, every time. HTTP is stateless in its raw form - if you do a GET to a particular URL, you get (theoretically) the same response every time. The exception of course is when we start adding statefulness on top, eg with ASP.NET web apps :) But if you think of a static website with only HTML files and images, you'll know what I mean.

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Stateless means there is no memory of the past. Every transaction is performed as if it were being done for the very first time.

Stateful means that there is memory of the past. Previous transactions are remembered and may affect the current transaction.

  Stateless:

     //The state is derived by what is passed into the function

        function int addOne(int number)
        {
        return number + 1;
        }

  Stateful:

     //The state is maintained by the function

        private int _number = 0; //initially zero

        function int addOne()
        {
        _number++;
        return _number;
        }

Refer from: https://softwareengineering.stackexchange.com/questions/101337/whats-the-difference-between-stateful-and-stateless

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