Introduction to Servlet
Servlet is basically a JAVA program that runs particularly inside JVM or {JAVA Virtual Machine} on the Web server. It is generally used to make/create Dynamic web applications and web pages.
It is a technology that is used to develop the Dynamic web applications. It uses the JAVA language for its work of developing web pages. This technology is secured, scalable, and robust because it uses JAVA technology which provides the same features.
Understanding
It is a small program that uses and runs on the JAVA language that extends the capabilities of a server. They are used to develop both the static as well as a dynamic web application.
How does it make working so easy?
As earlier, we had told you that the it makes our work so much easy just because it uses the JAVA programming language that provides us many features like secure, scalable and robust which makes it so easy to use and easy to work over it.
What can you do with it?
We can do a lot more things with it. The main and the basic thing we do with it the development of the static and dynamic webpages for web applications. This technology is very similar to CGI {Common Gateway Interface} but due to the drawbacks of CGI Servlet overcame it. If we talk about the difference the main difference between them is efficient and portable and data sharing is possible where it can handle the cookies but on the other hand, CGI is not portable and sharing data is impossible then resultant it cannot handle the cookies also. So these are the drawbacks of CGI.
Servlets API’s
It builds from two packages:
- Javax.servlet {basic}
- Javax.servlet http{advance}
Components
- Servlet
- ServletRequest
- Filter
- ServletConfig
- HttpServlet
- ServletResponse
- GenericServlet
- HttpServletRequest
Advantages
Some of the advantages are described below.
- Portable / Platform Independent: As written in JAVA, therefore, it is portable.
- Efficient and Scalable: Once it is loaded on a Web server, then it instantly starts fulfilling the requirements of clients.
- Robust: By the top features of JAVA like garbage collection, exception handling, etc. it is also known as robust.
- Easy Data Sharing: Data sharing is possible and very easy which was not in CGI.
- Less Expensive: Its cost is lower as a comparison to others.
- New Process: It does not use a new process every time. It removes the overhead of a new process, therefore, it also saves memory.
Servlet Container
Its Container is also known as the Servlet Engine that provides a very efficient run time environment for Java Servlet components. In other words, basically, it is a system that manages the component of JAVA Servlet to handle the request of the clients.
Services provided:
- Network service
- Security service
- Session management
- Resource management
- Manage container
Life Cycle and Working of Servlet
It contains 5 steps in its Life-Cycle
Step 1: Loading.
(Whenever the server starts the container of it deploys and loads all the servlet. During this step it creates ServletContext Object which is an interface to communicate easily with the container)
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Step 2: Creating Instance of Servlet.
(When all the Servlet classes are loaded, the container creates the instance for each class. The container creates only one instance for a single class and requests to the servlet executed on the same instance)
Step 3: Invoke init() method.
When all instances created then its init() method is invoked. This method is used for the initialization. There are many init parameter which we can specify in the web.xml file.
<servlet>
<servlet-name>MyServlet</servlet-name>
<servlet-class>com.XYZ.MyServletDemo</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
Now the init method for class co.XYZ.MyServletDemo will be invoked during container startup.
Step 4: Invoke Service() method.
(Every time the server receives requests for the servlet, it gets a new thread that calls service() method. When the Servlet is Generic then request is served by service()method, HttpServlet then service() method receives the request.)
Step 5: Invoke destroy() method.
(When Container shutdown, then it unloads all the servlet classes and interface and calls destroy() method for each initialized It.)
Career Growth in this Technology
This is the best technology for the career growth of a student who has an interest in coding language but the student should be sharped for this and there are a lot of opportunities for him. Every company needs such types of technology and the employee with the experts.
Conclusion
There are several technologies that are using according to our needs or requirements. It is the most used technology for making web applications due to it’s easy to use interface, while some other technology could also be used as its alternative. But it is best for all technology used for web applications.
Recommended Articles
This has been a guide to What is Servlet?. Here we have discussed the working, components, advantages along with the life cycle, and career growth in servlet. You may also look at the following articles to learn more –
