Why is it said that HTTP is a stateless protocol

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HTTP has HTTP Cookies  Cookies allow the server to track the user state  the number of connections  last connection  etc   HTTP has persistent connections  Keep-Alive  where several requests can be sent from the same TCP Connection

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What is stateless    Once the request is made and the response is rendered back to the client the connection will be dropped or terminated  The server will forget all about the requester   Why stateless    The web chooses to go for the stateless protocol  It was a genius choice because the original goal of the web was to allow documents web pages  to be served to extremely large no  of people using very basic hardware for the server   Maintaining a long-running connection would have been extremely resource-intensive   If the web were chosen the stateful protocol then the load on the server would have been increased to maintain the visitor s connection

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HTTP is called as a stateless protocol because each request is executed independently  without any knowledge of the requests that were executed before it  which means once the transaction ends the connection between the browser and the server is also lost   What makes the protocol stateless is that in its original design  HTTP is a relatively simple file transfer protocol    make a request for a file named by a URL  get the file in response  disconnect    There was no relationship maintained between one connection and another  even from the same client  This simplifies the contract between client and server  and in many cases minimizes the amount of data that needs to be transferred

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Modern HTTP is stateful  Old timey HTTP was stateless  Before Netscape invented cookies and HTTPS in 1994 http could be considered stateless   As time progressed more and more stateful aspects were added for a myriad of reasons  including performance and security  While HTTP 1 originally sought out to be stateless many HTTP 2 components are the very definition of stateful   HTTP 2 abandoned stateless goals  No reasonable person can read the HTTP 2 RFC and think it is stateless  The errant  quot HTTP is stateless quot  old time dogma is false and far from the current reality of stateful HTTP  Here s a limited  and not exhaustive list  of stateful HTTP 1 and HTTP 2 components   Cookies  named  quot HTTP State Management Mechanism quot  by the RFC  HTTPS  which stores keys thus state  HTTP authentication requires state  Web Storage  HTTP caching is stateful  The very purpose of the stream identifier is state   It s even in the name of the RFC section   quot Stream States quot   Header blocks  which establish stream identifiers  are stateful  Frames which reference stream identifiers are stateful  Header Compression  which the HTTP RFC explicitly says is stateful  is stateful  Opportunistic encryption is stateful   Section 5 1 of the HTTP 2 RFC is a great example of stateful mechanisms defined by the HTTP 2 standard  Is it safe for web applications to consider HTTP 2 as a stateless protocol  HTTP 2 is a stateful protocol  but that doesn t mean your HTTP 2 application can t be stateless  You can choose to not use certain stateful features for stateless HTTP 2 applications by using only a subset of HTTP 2 features  Cookies and some other stateful mechanisms  or less obvious stateful mechanisms  are later HTTP additions  HTTP 1 is said to be stateless although in practice we use standardized stateful mechanisms  like cookies  TLS  and caching  Unlike HTTP 1  HTTP 2 defines stateful components in its standard from the very beginning  A particular HTTP 2 application can use a subset of HTTP 2 features to maintain statelessness  but the protocol itself anticipate state to be the norm  not the exception  Existing applications  even HTTP 1 applications  needing state will break if trying to use them statelessly  It can be impossible to log into some HTTP 1 1 websites if cookies are disabled  thus breaking the application  It may not be safe to assume that a particular HTTP 1 application does not use state  This is no different for HTTP 2  Say it with me one last time  HTTP 2 is a stateful protocol

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If protocol HTTP is given as State full protocol browser window uses single connection to communicate with web server for multiple request given to web application this gives chance to browser window to engage the connections between browser window and web servers for long time and to keep them in idle state for long time This may create the situation of reaching to maximum connections of web server even though most of the connections in clients are idle

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HTTP is a connectionless and this is a direct result that HTTP is a stateless protocol  The server and client are aware of each other only during a current request  Afterwards  both of them forget about each other  Due to this nature of the protocol  neither the client nor the browser can retain information between different request across the web pages

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From Wikipedia      HTTP is a stateless protocol  A stateless protocol does not require   the server to retain information or status about each user for the   duration of multiple requests       But some web applications may have to track the user s progress from   page to page  for example when a web server is required to customize   the content of a web page for a user  Solutions for these cases   include          the use of HTTP cookies    server side sessions    hidden variables  when the current page contains a form   and   URL-rewriting using URI-encoded parameters  e g    index php session id some unique session code       What makes the protocol stateless is that the server is not required to track state over multiple requests  not that it cannot do so if it wants to   This simplifies the contract between client and server  and in many cases  for instance serving up static data over a CDN  minimizes the amount of data that needs to be transferred   If servers were required to maintain the state of clients  visits the structure of issuing and responding to requests would be more complex   As it is  the simplicity of the model is one of its greatest features

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I think somebody chose very unfortunate name for STATELESS concept and that s why the whole misunderstanding is caused  It s not about storing any kind of resources  but rather about the relationship between the client and the server    Client  I m keeping all the resources on my side and send you the  list  of all the important items which need to processed  Do your job   Server  All right   let me take the responsibility on filtering what s important to give you the proper response    Which means that the server is the  slave  of the client and has to forget about his  master  after each request  Actually  STATELESS refers only to the state of the server    https   www ics uci edu  fielding pubs dissertation rest arch style htm sec 5 1 3

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HTTP is stateless  TCP is stateful  There is no so-called HTTP connection  but only HTTP request and HTTP response  We don t need anything to be maintained to make another HTTP request  A connection header that is  keep-alive  means the TCP will be reused by the subsequent HTTP requests and responses  instead of disconnecting and re-establishing TCP connection all the time

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Because a stateless protocol does not require the server to retain session information or status about each communications partner for the duration of multiple requests   HTTP is a stateless protocol  which means that the connection between the browser and the server is lost once the transaction ends

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Even though multiple requests can be sent over the same HTTP connection  the server does not attach any special meaning to their arriving over the same socket   That is solely a performance thing  intended to minimize the time bandwidth that d otherwise be spent reestablishing a connection for each request   As far as HTTP is concerned  they are all still separate requests and must contain enough information on their own to fulfill the request   That is the essence of  statelessness    Requests will not be associated with each other absent some shared info the server knows about  which in most cases is a session ID in a cookie

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