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What is a
servlet?
Servlets are modules that extend request/response-oriented
servers,such as Java-enabled web servers. For example, a
servlet might be responsible for taking data in an HTML
order-entry form and applying the business logic used to
update a company’s order database. Servlets are to servers
what applets are to browsers. Unlike applets, however,
servlets have no graphical user interface.
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Whats the
advantages using servlets over using CGI?
Servlets provide a way to generate dynamic documents that
is both easier to write and faster to run. Servlets also
address the problem of doing server-side programming with
platform-specific APIs: they are developed with the Java
Servlet API, a standard Java extension.
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What are the
general advantages and selling points of Servlets?
A servlet can handle multiple requests concurrently, and
synchronize requests. This allows servlets to support
systems such as online
real-time conferencing. Servlets can forward requests to
other servers and servlets. Thus servlets can be used to
balance load among several servers that mirror the same
content, and to partition a single logical service over
several servers, according to task type or organizational
boundaries.
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Which
package provides interfaces and classes for writing
servlets? javax
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What’s the
Servlet Interface?
The central abstraction in the Servlet API is the Servlet
interface. All servlets implement this interface, either
directly or, more
commonly, by extending a class that implements it such as
HttpServlet.Servlets > Generic Servlet > HttpServlet >
MyServlet.
The Servlet interface declares, but does not implement,
methods that manage the servlet and its communications with
clients. Servlet writers provide some or all of these
methods when developing a servlet.
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When a
servlet accepts a call from a client, it receives two
objects. What are they?
ServletRequest (which encapsulates the communication from
the client to the server) and ServletResponse (which
encapsulates the communication from the servlet back to the
client). ServletRequest and ServletResponse are interfaces
defined inside javax.servlet package.
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What
information does ServletRequest allow access to?
Information such as the names of the parameters passed in
by the client, the protocol (scheme) being used by the
client, and the names
of the remote host that made the request and the server
that received it. Also the input stream, as
ServletInputStream.Servlets use the input stream to get
data from clients that use application protocols such as
the HTTP POST and GET methods.
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What type of
constraints can ServletResponse interface set on the
client?
It can set the content length and MIME type of the reply.
It also provides an output stream, ServletOutputStream and
a Writer through
which the servlet can send the reply data.
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Explain
servlet lifecycle?
Each servlet has the same life cycle: first, the server
loads and initializes the servlet (init()), then the
servlet handles zero or more client requests (service()),
after that the server removes the servlet (destroy()).
Worth noting that the last step on some servers is done
when they shut down.
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How does
HTTP Servlet handle client requests?
An HTTP Servlet handles client requests through its service
method. The service method supports standard HTTP client
requests by dispatching each request to a method designed
to handle that request.
