| | | | | | Question Answer Tutorial - JAVA->SERVLET | | | | | | | Question: What is different between web server and application server?
| | | Answer: A web server responsibility is to handler HTTP requests
;from client browsers and respond with HTML/>response. A web server understands HTTP language and runs&
nbsp;on HTTP protocol./>Apache Web Server is kind of a web server and th
en we have specific containers that can execute/>servlets and JSPs known as servlet container, for example&
nbsp;Tomcat./>Application Servers provide additional features such as Enterpr
ise JavaBeans support, JMS Messaging/>support, Transaction Management etc. So we can say that&nb
sp;Application server is a web server with/>additional functionalities to help developers with enterprise a
pplications.
| | | | | | | | | | | | Question: Which HTTP method is non-idempotent?
| | | Answer: A HTTP method is said to be idempotent if it retur
ns the same result every time. HTTP methods GET,/>PUT, DELETE, HEAD, and OPTIONS are idempotent method and&n
bsp;we should implement our application to make/>sure these methods always return same result. HTTP method&
nbsp;POST is non-idempotent method and we/>should use post method when implementing something that ch
anges with every request./>For example, to access an HTML page or image, we
;should use GET because it will always return the/>same object but if we have to save customer informati
on to database, we should use POST method./>Idempotent methods are also known as safe methods and
;we don’t care about the repetitive request/>from the client for safe methods.
| | | | | | | | | | | | Question: What is the difference between GET and POST method?
| | | Answer: GET is a safe method (idempotent) where POST is non-ide
mpotent method/>We can send limited data with GET method and it’s&nbs
p;sent in the header request URL whereas we can send/>large amount of data with POST because it’s part of&n
bsp;the body/>GET method is not secure because data is exposed in&n
bsp;the URL and we can easily bookmark it and send/>similar request again, POST is secure because data is
;sent in request body and we can’t bookmark it/>GET is the default HTTP method whereas we need to&nbs
p;specify method as POST to send request with POST/>methodHyperlinks in a page uses GET method
| | | | | | | | | | | | Question: What is MIME Type?
| | | Answer: The "Content-Type" response header is known as MIME Type.&nb
sp;Server sends MIME type to client to let/>them know the kind of data it’s sending. It helps&nbs
p;client in rendering the data for user. Some of the/>mostly used mime types are text/html, text/xml, application/xml
etc./>We can use ServletContext getMimeType() method to get the&
nbsp;correct MIME type of the file and use it/>to set the response content type. It’s very useful in
downloading file through servlet from server.
| | | | | | | | | | | | | Question: What is a web application and what is it’s directory structure?
| | | Answer: Web Applications are modules that run on server to prov
ide both static and dynamic content to the/>client browser. Apache web server supports PHP and we
;can create web application using PHP. Java/>provides web application support through Servlets and JSPs
;that can run in a servlet container and/>provide dynamic content to client browser./>Java Web Applications are packaged as Web Archive (WAR)&nb
sp;and it has a defined structure like belowimage./>![]() Servlet01
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