Web applications

The basics of web applications or how  the web applications work first of all let us understand what’s called a web  application a web application is a piece  of software which can be accessed from a  browser and you know what’s called a  browser a browser is an application that  you use for browsing the internet and the examples are your ie or Firefox or Google Chrome or suffer you all know about that technically speaking we can  call a web application a web server  although there is a difference application management services in the  sense that a web server can host  multiple applications but for the time  being let’s call it web application a web server.

A web server is actually  network application running on some  machine listening on a port the browser  is actually called a web client or more  formally we call that a user isn’t and in fact web clients are not only  browsers but any application which can  speak to a web server like your see URL  or telnet they are also our clients or user agents so the web client or the user region communicates with the web server to get its job done and for this communication and actually for any communication both the parties need to  use the same set of rules or grammar which we call protocol in technical  terms ah you got what is called a protocol it’s simple like when two  parties are communicating for example  when two people are communicating they need to use the same language and the same set of grammar rules so that they  can understand each other similarly in computer science when two applications are communicating they you and they need to use the same set of  rules which we call protocol and the browsers can speak some standard protocols  like the HTTP protocol.

The FTP protocol  the Web Socket protocol are there are  many protocols which the browsers can  speak in their standards and each of  these protocols are suitable for  different kind of tasks for example the  FTP protocol is used for transferring  files and among all these protocols the  HTTP protocol is the merge protocol in  the web client and the web server club  that means uh most of the times the web  client and the web servers speak to one  another using the HTTP protocol and in  fact in this whole tutorial we are going  to focus only on HTTP protocol so let’s  dig somewhat more into the HTTP protocol  or to understand HTTP protocol we need  to start or let’s start with what is  called a web resource or a resource as  commonly said it is SUSE a document like  an HTML document or a PDF document or  logician document or an XML file or any  kind of document which is hosted by a  web server.

 Web client can access those documents through a web server the source could be either static or dynamic a resource which does not change it’s called a static resource that means it’s like  some static file sitting in the web servers hard disk or sitting somewhere  which the web server has got access to  and when a request for a resource comes  from a web client the web servers passes  that as resource to the web client  straight in contrast a dynamic resource is generated on the fly in the sense  that when a request for a dynamic  resource comes from a web client the web  server o builds the resource on the flyer for example suppose a web server  has a resource which embeds the current  time either in a session or some XML  document or an HTML page or whatever so  when is request for that particular  resource comes from a web client the web  server gets the current.

The system and push that into a JSON  document build suggestion document or an  XML document or an HTML document  embedding that particular time into it  and then it sends back that document to the web client each resource on the web  in the world is identified by a unique  URL which is actually unique string I should be more clear when we look at an  example so this is an example of a whorl  which points to a unique resource in the  world and this part of the oil is the protocol and this part identify the web  server in the world and this is the path  of the resource in the web server we  will talk about URL more in some later video let’s go back to HTTP now so HTTP  protocol is basically request response  protocol that means whenever the web  plan needs to do some operation on a  source like reading it or updating it or  deleting it or creating a new resource  or any kind of operation the web plan  first establishes a connection with your web server where the resources are  hosted and then they were clients and  sell request to it the request contains the details of what the web plant once liked which operation it ones at all  while the web server receives a request  it responds with a response back to the web client that means it sends is a  spawn  back to the web client and the content  of the response depends on what was  requested for example if the client  asked to read a resource this server can either put the resource in the response  or in from the client then the resource is not available with me and you go to  somewhere else for the resource or something like that and then after the  response is given to the web client the connection is closed and the web server  does not remember anything about the  past connections and who the clients  where that means next time if the client  sends endless requests to the server the  web server will treat that request as a  new request coming from a new web client  and because of this nature the HTTP  protocol is called a stateless protocol  and this one pair of requests and  response is called an HTTP transaction so this was a basic overview of how web  servers and web clients working sureworks

By Anurag Rathod

Anurag Rathod is an Editor of Appclonescript.com, who is passionate for app-based startup solutions and on-demand business ideas. He believes in spreading tech trends. He is an avid reader and loves thinking out of the box to promote new technologies.