JSP

JavaServer Pages (JSP) is a technology that helps software developers create dynamic web pages based on HTML and XML, among other types of documents. JSP is similar to PHP but uses the Java programming language.

What is it used for?

The JavaServer Pages technology allows for the generation of dynamic web content, such as HTML, DHTML, XHTML, and XML files, to be included in a web application. JSP files are a way to implement server-side dynamic page content. JSP files enable a web server, such as Apache Tomcat, to add content dynamically to HTML pages before sending them to the requesting browser.

When a JSP file is deployed on a web server that provides a servlet engine, it is preprocessed into a servlet that runs on the server. This contrasts with JavaScript™ on the client side (within tags), which runs in a browser. A JSP page is ideal for tasks that are better executed on the server, such as accessing databases or calling Enterprise Java™ beans.

In this same vein, as we discuss the importance of JSP for creating dynamic web pages, remember how crucial it is to have a VPS service in your company to manage data effectively and provide your business with the best conditions for growth.

A VPS, or virtual private server, is a web hosting service obtained by dividing a physical server into multiple virtual servers, each with dedicated resources and isolated from the others.

Operationally, a VPS cloud works like other web hosting services, offering a space permanently connected to the internet where we can upload our website's content so others can access it.

How to create a JSP file?

You can create and edit a JSP file in an HTML editor by adding your own text and images using HTML, JSP code, or JavaScript, including Java source code within scriptlet codes. Typically, JSP files have the file extension .jsp. Additionally, the JSP specification recommends that JSP fragment files have the extension .jspf. If this convention is not followed, the JSP validator will treat the JSP fragments as regular standalone JSP files, which may result in compilation errors.

The Sun Microsystems JSP 1.2 Specification provides the ability to create custom JSP tags. Custom tags simplify complex actions and give developers greater control over the content of the pages. Custom tags are gathered in a library (taglib).

A tag library descriptor file (taglib.tld) is an XML document that provides information about the tag library, including the taglib's short name, a description of the library, and code descriptions. See the Sun Microsystems JSP 1.2 Specification for more information.

To use custom JSP 1.2 tag libraries, you can import the .tld library and .jar files into your project to use or associate them as web library projects. You can also refer to a TLD file using a URI.

It is important to understand this entire process of file creation to be informed about the fundamentals of your web. Also, remember the advantages of having a VPS cloud. 

We will have guaranteed resources like in a dedicated server. A VPS cloud has an isolated environment with its own dedicated RAM and CPU, so no other user can use those resources.

Additionally, it is highly customizable. VPS clouds share the same hardware with other VPSs, but their software is entirely independent, allowing you to access and make any changes or improvements to the configuration.

The main advantage of a VPS cloud is that it has many of the benefits of a dedicated server but at a fraction of the cost, making it an excellent option for users who need more freedom in usage and configuration.

How does it work?

The engine behind JSP pages is based on Java servlets—Java programs designed to run on the server—though the number of developers who can tackle JSP programming is much larger, as it is significantly easier to learn than servlets.

In JSP, we create pages similarly to how we create them in ASP or PHP—two other server-side technologies. We generate files with a .jsp extension that include Java statements to be executed on the server within the HTML tag structure.

Before the files are functional, the JSP engine carries out a translation phase of that page into a servlet, implemented in a class file (Java byte codes). This translation phase usually occurs when the first request for the .jsp page is received, although there is an option to precompile into code to avoid waiting time the first time a client requests the page.

Servlets and JSP?

Servlets and JavaServer Pages (JSPs) are two methods of creating dynamic web pages on the server using the Java language. In this sense, they are similar to other methods or languages such as PHP, ASP, or CGI programs that generate web pages on the server. However, they differ from them in several ways.

Firstly, JSPs and servlets run on a Java virtual machine, which allows them to be used on any type of computer, provided there is a Java virtual machine for it.

Each servlet (or JSP, from now on we'll use them interchangeably) runs in its own thread, meaning it operates in its own context; however, it does not start executing each time it receives a request, but persists from one request to the next, so there is no time wasted in invoking it (loading program + interpreter). Its persistence also allows it to perform certain tasks more efficiently, such as connecting to databases and managing sessions.

JSPs are, in fact, an alternative way of creating servlets since the JSP code is translated into Java servlet code the first time it is invoked, and thereafter, it is the new servlet code that executes, producing the HTML code that makes up the response web page.

What advantages does it have?

The performance of a JSP page is the same as that of the equivalent servlet, as the code is compiled like any other Java class. At the same time, the virtual machine will dynamically compile to machine code the parts of the application that require it. This makes JSP perform well and be more efficient than other web technologies that execute code in a purely interpreted manner.

The main advantage of JSP over other languages is that Java is a general-purpose language that extends beyond the web world and is suitable for creating classes that handle business logic and data access in a neat way. This allows for a layered separation of web applications, leaving the part responsible for generating the HTML document in the JSP file.

Another advantage is that JSP inherits Java's portability, and it is possible to run applications on multiple platforms without changes. It is common for developers to work on one platform and have the application run on another.

We can summarize the advantages as follows:

• Independence from the web server.
• Replacement of the servlet API with sets of markup elements (tags) and programming fragments (scriptlets).
• Highly recommended for accessing the web server in multi-tier architectures.
• Separation of static content from dynamic content.
• Separation of dynamic content from presentation format.