Both JSP and Servlet are important concepts pertaining to using Java for building web-based applications. Basically, a Servlet is HTML in Java while a JSP is Java in HTML. Any typical web development interview can have several JSP and Servlet-based Java interview questions.
Although much of the purpose served by JSP and Servlet is the same, there are several important differences between the two. Before delving deeper into dissimilarities between the two Java concepts, let’s first build a good understanding of them.
1. Difference Between Servlet and JSP
Java Servlets or simply Servlets are programs that run on some web or application server. They act as a middle layer between an inbound request from a web browser or an HTTP client and applications or databases present on the HTTP server. Servlets allow for:
- Collecting user input via web page forms
- Displaying records from a database or some other source
- Dynamically creating web pages
Since they are drafted in Java, Servlets are platform-independent. A Servlet has access to the complete functionality of Java class libraries. Servlets are able to interact with applets, databases, and software via sockets and RMI mechanisms.
JSP full form is Java Server Pages. It is a technology that enables developing web pages with support for dynamic content. JSP enables developers to insert Java code in HTML web pages by using special JSP tags that typically starts with <% and ends with %>.
A JSP component is a type of Java Servlet that fills the role of a user interface for a Java-based web application. JSPs combine HTML or XHTML code, embedded JSP actions and commands, and embedded JSP actions.
It is possible to use JSP tags for a multitude of purposes, ranging from retrieving data from a database to accessing JavaBeans components and sharing information between requests.
JSP is a fundamental part of Java Enterprise Edition. Hence, it is a comprehensive platform for building enterprise-level applications.
2. Servlet vs. JSP: Important Differences that You Must Know
- Custom Tags
Servlets offer no provision for building custom tags that can directly call Java beans. The JSP programming offers an advantage in this scenario as developers can build custom tags in JSP that can directly call Java beans.
Technically, a JSP is a text document that contains static and dynamic data. While the static data is represented in a text-based format – such as HTML, XML, and SVG – the JSP elements represent the dynamic data.
A servlet is a Java class that extends the abilities of servers hosting applications following a request-response model.
Servlets are typically used for extending the applications hosted by web servers. Nonetheless, they can respond to various types of requests too. Specifically for such applications, HTTP-specific servlet classes are specified by the Java Servlet technology.
- Ease of Coding
Although both JSP and Servlets are capable of generating dynamic content, the former is a web page scripting language and the latter are Java programs. Coding in JSP is much easier than coding Java Servlets. Moreover, JSP is compiled into Java Servlets.
In a Java Servlet, we need to implement each and everything like business logic. A single Servlet file contains both business logic and presentation logic. On the contrary, business logic is separated from presentation logic using JavaBeans in JSP.
Modifying a Java Servlet requires extensive time. This is because it demands to reload, recompiling, and restarting the server. Comparatively, JSP modifications are fast. A simple refresh will suffice to execute all the latest changes.
- MVC Pattern
While the servlet plays a controller role in MVC pattern, the JSP behaves as the view i.e. it is used for displaying output.
Any package that needs to be used in a Java Servlet is required to be imported on top of the servlet. No such condition is mandatory for the JSP, where a package can be imported anywhere at the top, middle, or bottom.
Both Java Servlets and Java Server Pages serve the same purpose as that of the programs executed using the Common Gateway Interface i.e. CGI. Although both are better than CGI, JSPs are slower compared to Servlets.
A Servlet comes in a precompiled form. Hence, it needs to be executed only. JSP is slower than servlets. This is because the initial step in JSP lifecycle is translating JSP to Java code and then proceeding to compilation.
Servlets implement a component-based, platform-independent method for developing web-based apps but without the performance restrictions of CGI programs. Moreover, Java Servlets have access to the complete set of Java APIs and they also offer better-then-CGI performance.
Other than having the ability to execute within the address space of a web server, Servlets don’t necessitate for developing a separate process for managing each and every client request. Using Servlets and JSP are advantageous overusing CGI.
- Session Management
In JSP, session management is enabled automatically. Contrarily, the session management in a Java Servlet is disabled by default. It needs to be enabled explicitly.
- Support for Requests
While JSP only accepts HTTP requests, a Java Servlet can accept all types of protocol requests. Moreover, we can override the service() method in Servlet but doing the same is not allowed in JSP programming.
- Use Cases
Both JSP and Servlets enable the creation of web-based applications. However, the preference is different. JSP is preferred when not much data processing is required. On the other hand, Java Servlets are best for using when heavy data manipulation and processing is needed.
Servlets are server-side programs developed in Java. JSP, on the other hand, is an interface built on top of Java Servlets. It embeds HTML code with some basic Java code. JSP can take care of the UI and cuts the effort required for designing screens.
The custom tags feature of JSP allows building reusable components, hence offering more flexibility than Servlets. Moreover, JSP is the go-to option for dealing with cookie management as well as session tracking.
Nonetheless, Servlets are far too more powerful than JSP in addition to the fact that no JSP can exist without the concept of Servlets.
The main difference between the Web server and application server is that web server is meant to serve static pages e.g. HTML and CSS, while Application Server is responsible for generating dynamic content by executing server-side code e.g. JSP, Servlet or EJB.