Stateless vs Stateful

Question

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 at least 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  e g  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 transferred  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

User · Answer

The adjective Stateful or Stateless refers only to the state of the conversation  it is not in connection with the concept of function which provides the same output for the same input  If so any dynamic web application  with a database behind it  would be a stateful service  which is obviously false   With this in mind if I entrust the task to keep conversational state in the underlying technology  such as a coockie or http session  I m implementing a stateful service  but if all the necessary information  the context  are passed as parameters I m implementing a stateless service  It should be noted that even if the passed parameter is an  identifier  of the conversational state  e g  a ticket or a sessionId  we are still operating under a stateless service  because the conversation is stateless  the ticket is continually passed between client and server   and are the two endpoints to be  so to speak   stateful

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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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Money transfered online form one account to another account is stateful  because the receving account has information about the sender  Handing over cash from a person to another person  this transaction is statless  because after cash is recived the identity of the giver is not there with the cash

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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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Just to add on others  contributions    Another way is  look at it from a web server and concurrency s point of view     HTTP is stateless in nature for a reason   In the case of a web server  being stateful means that it would have to remember a user s  state  for their last connection  and  or keep an open connection to a requester  That would be very expensive and  stressful  in an application with thousands of concurrent connections      Being stateless in this case has obvious efficient usage  of resources   i e support a connection in in a single instance of request and response   No overhead of keeping connections open and or remember anything from the last request

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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  e g  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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We make Webapps statefull by overriding HTTP stateless behaviour by using session objects When we use session objets state is carried but we still use HTTP only

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I had the same doubt about stateful v s stateless class design and did some research  Just completed and my findings has been posted in my blog    Entity classes needs to be stateful The helper   worker classes should not be stateful

[terminology] Stateless vs Stateful

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