Introduction to JSP

Features of JSP

• It helps in reducing the length of the code by allowing the use of multiple tags, e.g., custom tags, action tags, etc.
• It is easier to connect websites to the databases.
• It allows reading/writing data easily in the database.
• It is easy to code using JSP as it allows the insertion of java code into HTML tags.
• It helps in developing dynamic web applications.
• It is secure, browser, and server-independent, so it doesn’t require recompilation.
• It is portable, powerful, flexible, and easy to maintain.

HTTP Protocols

JSP uses a client-server model, in which a client makes a request to the server and gets a response accordingly. The protocol that the webserver/browser uses to communicate is HTTP protocol, which works based on the request/response model.

Mainly used HTTP commands are HEAD, GET, PUT, POST, DELETE, TRACE, OPTIONS, and CONNECT.

Source: Link

The HTTP protocol is stateless. It means that no information/state is carried over between subsequent requests from a client. To overcome the stateless HTTP protocol, the server uses sessions to keep information between two subsequent requests of the same client.

Lifecycle of a JSP Page

The lifecycle of a JSP (JavaServer Pages) page consists of several phases from its creation to destruction, allowing dynamic content to be generated based on user requests. Understanding this lifecycle is crucial for developers working with JSP to create efficient and maintainable web applications. Let's discuss the different phases in detail:

Phases of the JSP Lifecycle

Translation: The JSP engine translates the JSP page into a servlet. During this phase, the JSP syntax is converted into Java code.

Compilation: The translated Java servlet code is compiled into bytecode that the JVM (Java Virtual Machine) can execute.

Initialization: When the servlet is first loaded (before it handles any requests), the init() method is called. This method is typically used for one-time startup processes such as resource allocation.

Execution: The service() method is invoked each time the server receives a request for the JSP page. This method generates the dynamic page content based on the request parameters and can be called multiple times throughout the lifecycle of the servlet.

Cleanup: When the servlet is about to be removed from use (typically when the server shuts down or the application is redeployed), the destroy() method is called. This method is used for cleanup activities, such as releasing resources.

Advantages and Disadvantages of JSP

Advantages of JSP

• JSP supports all the features of servlet technology. It also has better performance over other technologies available.
• It inherits the features of java technology such as multithreading, exception handling, database connectivity, etc.
• It enables the separation of content presentation from content generation, making it easier for developers to manage the application.
• It is highly scalable and provides flexibility in building dynamic web applications.
• It is built over java. Hence it is platform-independent.
• Its code is easy to write and maintain.
• There is no need for recompilation and redeployment in JSP.

Know Why is Java Platform Independent here.

Disadvantages of JSP

• The output of JSP is in HTML, which lacks advanced features.
• It is difficult to debug.

JSP v/s Servlet

Let’s have a look at the key differences between JSP and Servlet:

You can also read about the JSP Architecture and Lifecycle.

Frequently Asked Questions

What are implicit objects in JSP?

Implicit objects in JSP are pre-defined objects that are automatically available to the JSP page without explicit declaration. They provide access to request, response, session, and application data, among others. Examples include request, response, session, application, out, pageContext, config, page, and exception.

How many types of directives are there in JSP?

Ans: There are three directives in JSP:

1. Include: The include directive is used to insert the text contained in another file into the including JSP document.
2. Page: The page directive defines several page-dependent properties and communicates these to the JSP container. 
3. Taglib:  The taglib directive declares tag libraries used in a JSP page.

What are the action elements in JSP? 

Ans: The action tags are used to control the flow between pages and to use Java Bean. Some of the JSP action tags are given below:

• JSP: forward - used to forward the response and request to another resource.
• JSP: include - It is used to include other resources.
• JSP: useBean - It is used to create or locate bean objects.
• JSP: setProperty - It is used to set the values in bean objects.
• JSP: getProperty - It is used to print the value of the bean.
• JSP: plugin - It is used to embed other components.
• JSP: param - It is used to set the parameter value.
• JSP: fallback - It is used to print the message whether a plugin is working or not.

Conclusion

This blog discussed a basic introduction to JSP, including its important features and properties. JSP is a server-side scripting language used for creating dynamic web pages using java. It allows converting any HTML file to a JSP file by simply changing the file extension. JSP comes with many advanced features that help create and maintain a highly scalable web application.

If you are a beginner interested in learning and exploring other fields, you can follow our guided path to understand the core subjects of computers and get a good grip on DSA concepts.