JSP vs Servlet: Difference Between JSP & Servlet [2021]

Websites are collections of static files, for example, images, graphics, and HTML files. These websites are referred to as web applications if they provide dynamic functions when hosted on the servers.

Websites mostly work on a client-server paradigm where the client sends requests to the server, which, in turn, processes the queries and provides the desired outputs. This communication is done using the HTTP protocol. In this article, we will be taking a look at the difference between JSP and Servlet

Servlets are the server-side programs written in Java, which implement the Servlet interface and handle all the client requests to that server. Servlet acts as the middle layer between the client requests and the applications hosted on the server. Servlets are used to collect data from the users, for example, forms, and also to create web pages dynamically and present the results.

JSP, Java Server Pages, is also a technology similar to the Servlets and is used to create web applications. JSPs can be viewed as the extension of Servlets, as JSP is easier to maintain and provides more functionalities. Java Server Pages (JSPs) forms a fundamental part of the Java EE. 

What Are JSP and Servlet? 

JSP, an acronym for Java Server Pages, is an extensive collection of technologies, which are used to develop web pages. These web pages are developed by inserting Java codes into HTML pages by JSP tags. The collection can contain HTML, XML, or both with JSP actions and commands.

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JSP contains static as well as dynamic data, where dynamic data can be JSP elements, whereas the static data can be HTML, XML, SVG, or WYML files. Servlets generate dynamic content, interact with the client, and are maintained by Servlet engine containers. Servlets are used to extend the functions provided by the servers.

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Difference between Servlet and JSP

Servlets are a method to develop web applications by implementing them in a platform-independent and component-based approach. It does not abide by the performance-based restrictions of CGI programs (Common Gateway Interface). Servlets can access all the Java APIs and the JDBC API to access enterprise databases.

JSPs are utilised for server-side programming and are also used to create platform-independent, dynamic web applications. If we want to have a clear view of JSP vs. Servlet, we can compare them on the following factors to help decide which one is a better choice if there is any specific requirement.

Servlet

JSP

Servlets are faster as compared to JSP, as they have a short response time.  JSP is slower than Servlets, as the first step in the JSP lifecycle is the conversion of JSP to Java code and then the compilation of the code.
Servlets are Java-based codes. JSP are HTML-based codes.
Servlets are harder to code, as here, the HTML codes are written in Java.  JSPs are easier to code, as here Java is coded in HTML.
In an MVC architecture, Servlets act as the controllers.  In MVC architectures, the JSPs act as a view to present the output to the users. 
The service() function can be overridden in Servlets.  The service() function cannot be overridden in JSPs. 
The Servlets are capable of accepting all types of protocol requests.  The JSPs are confined to accept only the HTTP requests. 
Modification in Servlets is a time-consuming and challenging task, as here, one will have to reload, recompile, and then restart the servers. Modification is easy and faster in JSPs as we just need to refresh the pages.
Servlets require the users to enable the default sessions management explicitly, as Servlets do not provide default session management.  JSPs provide session management by default.
Servlets require us to implement the business logic and presentation logic in the same servlet file.  JSPs give us the flexibility to separate the business logic from the presentation logic using javaBeans. 
Servlets can handle extensive data processing.  JSPs cannot handle data processing functions efficiently. 
Servlets do not provide the facility of writing custom tags.  JSPs can provide the facility of building the JSP tags easily, which can directly call javaBeans. 
In Servlets, we do not have implicit objects. In JSPs, we have support for implicit objects. 
Servlets are hosted and executed on Web Servers.  JSP is compiled in Java Servlets before their execution. After that, it has a similar lifecycle as Servlets. 
We need to import all the packages at the top of the Servlets.  In JSPs, we can import packages anywhere in the file.

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The Advantages of using Servlets

  • Servlets load only one copy into the Java Virtual Machine. This makes their memory efficient and faster.
  • The response time is significantly less, as it saves time to respond to the first request. 
  • Servlets are easily accessible, as they use standard API that is used by a large number of web servers.
  • It is easy for development and is platform-independent.
  • Servlet’s usage doesn’t constrain the web servers. 
  • Servlets help developers access a large number of APIs, which are available for Java. 
  • It is very easy to maintain multiple Servlets for a single web application.
  • Servlet containers provide developers with the facility of support to several other features like resource management, sessions, security, persistent, etc. 
  • If servlets have multiple requests, the web containers provide threads to handle more than one request.

The Advantages of using JSPs

  • JSP can be used to write Servlets.
  • JSP is very easy to modify, and therefore, it makes it very convenient.
  • Developers can easily show and process information in JSP.
  • JSP can use the multithreading feature of Java.
  • JSP can be easily connected to the MYSQL databases. 
  • JSP can use the exceptional handling feature of Java.
  • JSP has better performance and scalability, as developers can embed dynamic elements into the HTML code.
  • JSP is based in Java and is platform-independent.

As we have now discussed the advantages of using Servlets and JSPs, we will now take a look at the disadvantages of using both of them, when compared to each other. 

Disadvantages of using Servlet

  • Servlets create threads and not a process when a request arrives.
  • It is harder to code and perform exception handling, as Servlet codes are not thread-safe by default.
  • Java Runtime Environment is necessary to run Servlets on the server.
  • Developing Servlets requires experience and a lot of knowledge of Java Servlets for development.
  • Only one Servlet is loaded into the JVM.
  • HTML code and Java code are interdependent and can cause errors if changes are not taken into consideration. 

Disadvantages of using JSP

  • It is very difficult for developers to perform database connectivity in JSP.
  • As the JSP is compiled on the server, it is not memory and time-efficient.
  • It is hard to track errors in JSP files because they are an extension to Servlets. The JSP codes are processed into Servlet codes for compilation.
  • As JSP is an HTML file, it doesn’t provide many features. 

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Conclusion

In this article, we have had a detailed review of both Servlets and JSPs, and also looked at the major differences between JSP and Servlet. In conclusion, we can say that Servlets are server-side programs and take care of the processing, whereas JSP is an interface that is built on top of Servlets to provide added functionalities. Because the JSP acts as an interface, developers can easily manage and integrate the UI part of the applications in JSP files.

JSP provides added flexibility compared to the Servlet, as JSP contains custom tags for building reusable codes. Servers are not beneficial for session management, as they are not enabled by default, whereas JSP makes session management and tracking due to its property of handling multiple requests on a single thread. 

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