1. Introduction
When developing any application, the selection of the right technology plays a significant role. However, the decision isn't always straightforward.
In this article, we'll provide a comparative view of three popular technologies of Java. Before jumping into comparison, we'll start by exploring the purpose of each technology and its lifecycle. Then, we'll see what their prominent features are and compare them on the basis of several features.
2. JSF
Jakarta Server Faces, formerly known as JavaServer Faces, is a web framework to build component-based user interfaces for Java applications. Like many others, it also follows an MVC approach. The “View” of MVC simplifies the creation of user interfaces with the help of reusable UI components.
JSF has a wide range of standard UI components and also provides the flexibility to define a new one through an external API.
The lifecycle of any application refers to various stages from its initiation to conclusion. Similarly, the lifecycle of the JSF application starts when a client makes an HTTP request and ends when the server responds with a response. The JSF lifecycle is a request-response lifecycle and handles two kinds of requests: initial requests and postback.
The lifecycle of a JSF application consists of two major phases: execute and render.
The execute phase is further divided into six phases:
- Restore View: Starts when the JSF receives a request
- Apply Request Values: Restoration of the component tree during a postback request
- Process Validations: Process all the validators registered on the component tree
- Update Model Values: Traverses the component tree and sets the corresponding server-side object properties
- Invoke Application: Handles application-level events such as submitting a form
- Render Response: Builds the view and renders pages
In the render phase, the system renders the requested resource as a response to the client browser.
JSF 2.0 was a major release that included Facelets, composite components, AJAX, and resource libraries.
Before Facelets, JSP was the default templating engine for JSF applications. With older releases of JSF 2.x, many new features were introduced to make the framework more robust and efficient. These features include support for annotations, HTML5, Restful, and stateless JSF, among others.
3. Servlet
Jakarta Servlets, formerly known as Java Servlets, extend the capability of a server. Usually, servlets interact with web clients using a request/response mechanism implemented by a container.
A servlet container is an important part of a web server. It manages servlets and creates dynamic content according to user requests. Whenever a web server receives a request, it directs the request to a registered servlet.
The lifecycle consists of only three phases. First, the init() method is invoked to initiate the servlet. Then, the container sends incoming requests to the service() method that performs all the tasks. Lastly, the destroy() method cleans up a few things and tears down the servlet.
Servlets have many important features, including native support for Java and its libraries, a standard API for web servers, and the powers of HTTP/2. Additionally, they allow asynchronous requests and create separate threads for each request.
4. JSP
Jakarta Server Pages, formerly known as JavaServer Pages, enable us to inject dynamic content into a static page. JSPs are the high-level abstraction of servlets because they are converted into servlets before execution begins.
The common tasks such as variable declaration and printing values, looping, conditional formatting, and exception handling are performed through the JSTL library.
The lifecycle of a JSP is similar to the servlet with one additional step — the compilation step. When a browser asks for a page, the JSP engine first checks whether it needs to compile the page or not. The compilation step consists of three phases.
Initially, the engine parses the page. Then, it converts the page into a servlet. Lastly, the generated servlet compiles into a Java class.
JSPs have many notable features such as tracking the session, good form controls, and sending/receiving data to/from the server. Because the JSP is built on top of the servlet, it has access to all important Java APIs such as JDBC, JNDI, and EJB.
5. Key Differences
Servlet technology is the foundation of web application development in J2EE. However, it doesn't come with a view technology, and the developer has to mix markup tags in with Java code. Additionally, it lacks the utilities for common tasks like building the markup, validating the requests, and enabling the security features.
JSPs fill the markup gap for the servlet. With the help of JSTL and EL, we can define any custom HTML tag to build a good UI. Unfortunately, JSPs are slow to compile, hard to debug, leave basic form validation and type conversion to the developer, and lack support for security.
JSF is a proper framework that connects a data source with a reuseable UI component, provides support for multiple libraries, and decreases the effort to build and manage applications. Being component-based, JSF always has a good security advantage over JSP. Despite all of its benefits, JSF is complex and has a steep learning curve.
In light of the MVC design pattern, the servlet acts as a controller and JSP as a view, whereas JSF is a complete MVC.
As we already know, the servlet will need manual HTML tags in Java code. For the same purpose, JSP uses HTML and JSF uses Facelets. Additionally, both provide support for custom tags, too.
There's no default support for error handling in servlet and JSP. In contrast, JSF provides a bunch of predefined validators.
Security has always been a concern in applications that transmit data over the web. JSPs that support only role-based and form-based authentication are lacking in this aspect.
Speaking about the protocols, JSP only accepts HTTP, whereas servlet and JSF support several protocols, including HTTP/HTTPS, SMTP, and SIP. All of these technologies advocate multithreading and necessitate a web container to run.
6. Conclusion
In this tutorial, we compared three popular technologies in the Java world: JSF, Servlet, and JSP. First, we saw what each technology represents and how its lifecycle progress. Then, we discussed the main features and limitations of each technology. Finally, we compared them on the basis of several features.
What technology should be chosen over the other totally depends on the context. The nature of the application should be the deciding factor.
The post Difference Between JSF, Servlet, and JSP first appeared on Baeldung.
