Understanding The Differences Between JSP Vs. Servlet

Updated 28 July 2022

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A website is a collection of static files, HTML (hypertext markup language) files, graphics and images and when hosted on a server, these websites provide different dynamic functions. Websites that provide a dynamic function can act as web applications. If you plan a career in web application development that uses Java components like JavaServer Pages (JSP) and Servlet, having in-depth knowledge about them can help you excel in your workplace. In this article, we explore the JSP vs. Servlet, understand the uses, advantages and disadvantages of both and discuss the difference in the life cycle of Servlet and JSP.

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Understanding The Basics Of JSP Vs. Servlet

Before defining the differences between JSP vs. Servlet, it is important to understand the terms independently. JSP is a technology widely used to create web applications like the Servlet. It is a text document containing two types of texts, dynamic data and static data. You can express the dynamic data in JSP elements and the static data elements in text-based formats like HTML, WML (wireless markup language), XML (extensible markup language) and SVG (scalable vector graphics). It is an extension of Servlet because JSP offers more functionality than a Servlet. Usually, a JSP page comprises JSP tags and HTML tags.

Servlet is a Java program module that runs on a server and can handle the client's request. Though a Servlet can handle other requests, it mainly extends the application that a web server hosts. Servlet works like a middle layer between a request from databases, clients and applications on the HTTP (hypertext transfer protocol) server. It provides an HTTP response as an HTML page. A Servlet helps in extending the capabilities of a server.

Reasons For Using A JSP

Here are a few reasons for using a JSP:

JSP's server page can access all Java APIs and many components of Java.
Processing of JSP occurs before it goes for compilation.
JSP is an essential part of the Java EE (Enterprise Edition), a platform for enterprise-level applications.

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Advantages Of Using JSP

Here are a few advantages of using JSP:

Allows a developer to write Servlets
Processes and shows information in JSP
Uses multi-threading Java feature
Uses Java's exceptional handling feature
Connects to the database of MySQL
Allows you to embed any dynamic elements into the HTML code that improves performance and scalability

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Disadvantages Of Using JSP

Here are a few disadvantages of using JSP:

For developers, it is challenging to perform database connections in JSP.
JSP is not time and memory-efficient because the compilation of JSP takes place on the server.
As JSP is an extension of Servlet, it is challenging to track errors in JSP.
JSP lacks many advanced features because it is an HTML file.

Reasons For Using A Servlet

Here are some reasons developer uses Servlet when developing web-based applications:

Developers use Servlet to take complete advantage of all Java features.
Servlet ensures high performance.
When developers do not want to build a separate process for handling every client request, they use a Servlet for developing web applications.

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Advantages Of Using Servlet

Here are a few advantages of using Servlet:

Help developers in accessing many APIs
Maintain Servlets for a single web app
Cause no constraint on the webserver
Easy to access
Make development easy
Provide developers with features like support facility, resource management and session security
Ensure less response time
Loads only a single copy into the Java virtual machine, making memory efficient and faster
Usage does not constraint the web servers
Ensure low response time because Servlet saves time to respond to the first request

Disadvantages Of Using Servlet

Here are a few disadvantages of using Servlet:

When a request arrives, instead of creating a process, Servlet creates a thread.
As Servlet codes are not thread-safe by default, it becomes challenging to code and perform exception handling.
Developers require the Java runtime environment (JRE) to run Servlets on the server.
Working with Servlets requires extensive experience and knowledge of Java Servlets.
The Java virtual machine (JVM) can load only one Servlet.
When using a Servlet, errors are high because the Java code and HTML code are interdependent.

Difference Between Servlet And JSP

Here are a few differences between Servlet and JSP:

Implementation

A developer can develop a Servlet in Java language and write the JSP in the HTML language. Also, Servlet is a Java code, whereas JSP uses a tag-based approach. As a result, coding a Servlet is challenging when compared with JSP.

Performance

By default, a Servlet is faster than JSP because the first step in the lifecycle of JSP is a translation of the text into Java code. Only in the second step, the compilation takes place, which makes JSP slower than Servlet. Also, the response time of Servlet is less in comparison with JSP, making Servlet a high-performance module. The performance of Servlet is high because it implements a component-based and platform-independent method for building web applications but with no restrictions.

Ease of coding and data processing

JSP is much easier to code because developers code Java in HTML language. In Servlet, developers write the HTML code in a Java language that makes coding complex. Another area where Servlet outsmarts JSP is that Servlet can handle extensive data processing, whereas JSP cannot handle data processing as extensively as Servlet.

Custom tags

The JSP programming allows a developer to build custom tags that they can use to call Java beans. Whereas, in Servlet, there is no provision of building custom tags that can directly call Java beans. In JSP, a custom tag is a user-defined language element.

Model view controller (MVC) pattern

The MVC pattern specifies that a web-based application comprises control information, presentation information and a data model. While a Servlet works like a controller that receives requests and sends the responses back, a JSP handles the view. JSP primarily helps in rendering the response that a Servlet returns.

Execution and exception handling

For executing Servlet components, a developer requires a Servlet container to explicitly complete the exception handling. But, for executing a JSP component, a developer requires Servlet and JSP containers. As JSP requires no exception handling often, developers prefer using JSP architecture over Servlet. There is no exception handling because the JSP equivalent Servlet is present.

Request type and session management

Servlets are architecture capable of accepting and processing different protocol requests, whereas JSP is compatible only with HTTP requests. Often, developers using Servlet may explicitly enable the default session management. Default session management is essential for web applications because it allows a server to remember its clients. By enabling the default session management, Servlet can serve the client better. This is another area where Servlet outclasses JSP. Because in JSP, the session management is on by default.

Modification

Making modifications in the Servlet is a time-consuming and complex task because every modification requires reloading, recompiling and restarting the server for the changes to reflect, making it a challenging task to accomplish. When developers use JSP, they do not face any modification problem because JSP features a refresh button that eliminates the need for reloading, recompiling and restarting. The developer clicks on the refresh button to get the changes reflected.

Persistence and business logic

When using a Servlet, developers use their implementation and persistence logic (HTML code) and business logic (Java code) in the same Servlet file. This is another reason why developers prefer using JSP over Servlet. The JSP provides a developer with the flexibility of separating business logic from persistence logic by using Java Beans.

Structure

A Servlet is similar to Java classes but JSP is a mix of JavaScript and HTML code. Though a JSP application converts to a Servlet on the compilation, JSP resembles PHP files containing Java code you embed in HTML codes. Another difference between Servlet and JSP is that developers can easily override the service () method in Servlet but cannot do the same in a JSP.

Use cases

Though developers can use JSP and Servlet to develop a web application, the choice may depend on many factors. When developers require little data processing, they prefer using JSP to create a web-based application. But, when the application requires intense data processing, developers switch to Servlets.

Difference Between JSP Vs. Servlet Life Cycles

In a Servlet, the first step is the creation of a Servlet object. After creating the object, the Servlet container invokes the initial method and initialises the Servlet. Then the service methods get invoked and complete the work and the destroy() method destroys the Servlet. The life cycle of a JSP differs from the Servlet. The JSP translates to a Servlet and the JSP starts behaving like a Servlet. After converting to a Servlet, it follows the life cycle of a Servlet. As the JSP has one extra step in the compilation process, it is slower in execution when compared with Servlet.

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