Jserv Architecture in 11i



Last updated on April 15th, 2017 at 03:42 am

Jserv Architecture in  11i

The servlet engine is not part of the web server, but a standalone server application. When executing a servlet request, the web server acts as a client,subrequesting servlets through the network (using the Apache JServ Protocol commonly known as the AJP protocol),converting the returned data and sending it back to the requesting client.

Apache JServ can be divided in two main parts:
1.Included in the web server and acting as an AJP client, is mod_jserv,
2.Acting as an AJP server, is Apache JServ.

mod_jserv
This is a module for the Apache Web Server completely written using C language. Its main task is to forward an HTTP request dispatched by the Apache Web Server to the Apache JServ servlet engine using the AJP protocol. When the servlet engine processes an AJP request, its results are converted back to HTTP and sent to the client.

Apache JServ
This is the servlet engine. It’s completely written in Java . This is a standalone server and for this reason does not require a particular web server to operate . It processes AJP requests returning back to its client (the web server) the output of the requested servlet.

The whole discussion could be understand by below steps
1.A client machine calls the Apache Web Server requesting a servlet.
2.Apache handles this HTTP request to mod_jserv module.
3. mod_jserv translates the HTTP request from the client into an AJP requests and contacts Apache JServ servlet engine using a TCP/IP network.
4.Apache JServ has already performed its initialization process and it’s ready to handle AJP requests.
5.Apache JServ translates the AJP request into a ServletRequest object, then creates a new ServletResponse object used by the servlet to return data to its requester.
6.During execution, until the end, all data passed to ServletResponse are converted into an AJP response and sent back to mod_jserv.
7.mod_jserv translates the AJP response into an HTTP response and forwards it back to the web server’s client.

 

Important Terms used in Jserv Techonology

Explanation for each term used in Jserv is given below

Apache JServ
– the 100% pure Java server application that acts as an independent servlet-request server.

mod_jserv
– the Apache module that converts HTTP requests to servlet requests, connecting to the proper servlet engine and sending back the HTTP response to the client.

Apache JServ Protocol(AJP)
– the protocol used to communicate between the web server and the servlet engine over a TCP/IP connection.

Servlet
– A servlet is a Java server side application that runs inside a network service, such as a web server.It responds to requests from clients, accepting client input and dynamically generating output. For example, a database querying servlet may receive a client’s query, run it against the connected database, process obtained data, and return formatted output to the client.

Servlet Repository
– is a collection of compiled servlets. A repository may be a single directory or a single compressed archive (jar or zip)

Servlet Zone
-A servlet zone defines the sandbox where servlets live during their life cycle. A zone defines the security environment where the executing servlet is restricted and allows context separation between different logical groups of servlets. A servlet zone is the servlet engine equivalent of a web server’s virtual host, separating servlets into different contexts.

Java Virtual Machine
– Interpreter for Java Bytecodes


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