25 Buffer Information | Adv Java Servlet programming Tutorial | advance java tutorial

#Buffer #Information: #Adv #Java #Servlet #programming #Tutorial #advance #java #tutorial (#Buffer is also called as #cache)
- Buffer is a temporary memory that holds output for temporary period. Browser window keeps the servlet program generated output in the buffer before displaying it as a webpage and usage buffer data across the multiple same request.

- In this process browser window may show old results collected from the buffer eventhough servlet is ready to give the updated result.

- To make browser window for not keeping outputs in the buffer we need to use cache-control or in program response header as shown below
res.setHeader("cache-control","no-cache"); //Based on HTTP 1.1 Server
or
res.setHeader("pragma","no-cache"); //Based on HTTP 1.0 server

Q. What happens "When buffer is not disabled"?

(By default buffer is enabled for every browser)
1a-1e indicates flow of execution to 1st request.
2a-2c indicates flow of execution to 2nd request
Note: 2nd request is gathering output from buffer of browser window.


Q. What happens "When buffer is disabled"?
==========================================
here each request is going to servlet program.
The buffer of browser window reduces network round trips between browser and server across the multiple same request at certain times, this buffer may become disadvantage for getting updated results from server then we need to disable it by using cache-control or response header like

res.setHeader("cache-control","no-cache"); //Based on HTTP 1.1 Server
or
res.setHeader("pragma","no-cache"); //Based on HTTP 1.0 server

Conclusion:
1) When servlet prgram generates homepage, about-us (or any static output/webpage) page kind of webpages then don't disable buffer of browser window.(because its response is static/fixed for multiple same request).
2) When servlet program generates live cricket score page, share market value page kind of web pages then disable buffer of browser window.
#What is the difference between request headers and response headers:
- Request header carry browser supplied internal input values to webresource program. These values are very useful in request processing.

- Response heades carry server or servlet program supplied instructions to browser window towards displaying web pages on browser window.