Servlet Container in Java

Servlet container in java is providing the runtime environment for the java and j2ee applications, basically, client will only request static web pages from web server, if suppose we want to read the web pages as input then we need to use servlet container in our application. It is the part of server which was running in a specified process. There are three types of servlet container steps available in java i.e. in process, standalone, and out of process. It performs many operations in life cycle management of our application.

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What is servlet container in java?

• We can dynamically generate the web pages on server side. Basically, servlet container is nothing but the web server part which was interacting with servlet.
• The servlet container is used to manage the life cycle of java component. Also, servlet container is used to manage the life cycle of java servlet.
• As we know that servlet container is the part of web server. Below are the states as follows.

1) In process
2) Out of process
3) Standalone

• The first process of servlet container is standalone; it is basically a java based server which was contains the web server which is to be an integral part of the single code. An example of servlet container is running of tomcat server.
• The second state of servlet container is in process, this process is divided from web server in servlet container, because on web server different program is running. The example of in process state servlet container is tomcat is running on inside JBOSS server.
• The third state of servlet container is out of process, in this state servlet container and web server is the different programs which was run in different processes.

How servlet container works in java?

• To execute the servlet code, we need servlet container. It is running on top of the java virtual machine.
• As we know that without java virtual machine we cannot execute the java code, so using java virtual machine we have running servlet container.
• Servlet container is running standalone or it also run without using web server.
• Servlet container component is the java based component. It is nothing but the compiled and executable program.
• The main use is to initialize and load the servlet. It is the implementation of java server pages and servlet technologies.
• Basically, servlet container will load the servlet class and calling the method name as init, Servlet container is calling this method first time.
• We have calling the init Method in servlet container for each method to construct the servlet request for the instance.
• After calling init method and constructing servlet request then we have invoking the method name as servlet service to pass the servlet request and servlet response.
• After shutting down the class of servlet it will calls the destroy method to unload the server class.

Web server process a request

• Web server is nothing but the software and hardware which was used the respond to client request which was made though from internet.
• The main work of java web server is to display the content of website. Web server is also supporting the simple mail transfer protocol.
• The HTTP server is understanding the URL and HTTP. Web server is nothing but the computer which was used to store the web server files and other files which was related to the web server.
• Web server is used to send and receive emails. Web server is also used in FTP (file transfer protocol) protocol to upload and download the files.
• We can also use the web server to publish and build the web pages of our application on internet.
• To perform the communication between web server and container web server is using the plugin which was provided by the container of servlet.
• It will manage the servlet container life cycle, which was contains the method calling, object creation, destroy and manage the object.

Responsibilities

• Using servlet container, the method and life cycle instances are handled and parsed by using a web container. The web container in servlet container will providing the facility of pooling management.
• It provides medium and inter servlet communication support to the browser and client.
• Servlet container in java is creating a new thread for every new request, so it will be supporting the multithreading concept. Servlet will initialize for every request and also it will sharing the one-time memory to every request.
• It also supports the JSP. Every servlet container java application is compiled by using JSP.
• Basically, servlet container is responsible to convert the JSP to servlet and also responsible for maintain the same.

Servlet Container Example

Below steps shows servlet container are as follows.

1) Create project template using spring initializer

Group – com. example
Artifact name – servlet-container
Name – servlet-container
Description – servlet-container
Package name – com. example.servlet-container
Packaging – Jar
Java – 11
Dependencies – spring web.

2) After generating project, extract files and open this project by using spring tool suite –

3) After opening project using spring tool suite check the project and its files –

4) Add the dependency –

Code:

<artifactinstaller> -- Start of artifactInstaller tab.
<groupid>org.apache.tomcat</groupid> -- Start and end of groupid tag.
<artifactid>tomcat</artifactid> -- Start and end of artifactid tag.
<version>${tomcat.version}</version> -- Start and end of version tag.
</artifactinstaller> -- End of artifactInstaller tab.

5) Create main java class

Code:

public class ServletContainerApplication extends HttpServlet {
public void doGet (HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setContentType ("html");
ServletOutputStream out = resp.getOutputStream ();
out.println ("");
out.println ("<title>Welcome to servlet container</title>");
out.println ("");
out.println ("<h1 id="Hi-There">Hi There!</h1>");
out.println ("");
}
}

6) Run the application –

Conclusion

Servlet container is nothing but the program which was runs continuously and manages the lifecycle of a specified component. There are three types of servlet container steps available in java i.e. in process, standalone, and out of process. Web server is accessed by using website domain name.

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