Introduction to JSP
To know and learn about JSP, we need to know a bit about Web Servers and Web Browsers. Web Browsers are the ones upon which one can work online. It is an application program which runs and displays www (World Wide Web) document. It acts as a medium between client and user. Web browsers parcel up the request to the protocols and then fetch the required information. Whereas Web Server is a program that provides services to the user when pinged. It sends back the response to the web browsers when asked for it. So Web Browser and Web Server though work together, but run on parallel paths.
What is JSP?
It is an acronym for Java Server Pages. It is a server-side technology which helps the developers or the users to generate web-based pages. It is a betterment feature to Servlets, developed by Sun Microsystems. This was developed in order to cover up all the flaws of Servlets. Servlets used to contain a combined logic of businesses and user interface. In JSP, presentation logic and business logic are separated. As we have scripted or used earlier, tags are used to define a certain action. In JSP, we define the special tag as “<% %>”. When we use JSP, we can implement, the Java API’s by default into the web-programming. Not only the Java API’s but JSP works with HTML and XML tags, which was earlier not possible. As we use in Java, JDBC database drivers can be utilized too. So dynamic querying of a database is possible. Apart from the regular usage, JSP provides more features like:
- Querying the database and retrieving information.
- Sharing information between two pages.
- Access Control.
Why do we Need JSP?
Being a server-side programming language, it helps in creating dynamic web pages. Not only with Java API’s, but a connection with the database is an added advantage, which was previously not possible. Action commands and textual data both can be combined in JSP. Dynamic content like check-boxes, action buttons can be extracted for their values. JSP can access JavaBeans or an object of it too.
Diagrammatic Explanation of Working with JSP:
Till now, we have seen so many uses of JSP, it is making a life of developers easier by letting them access so many amounts of data and other syntactical language scripts. A JSP (Java Server Page) is translated into a regular Servlet first. As any servlet would do, it translates the requests, but first time only unlike servlets. The result is obtained when the translator recognizes the file name with its extension as “.jsp”. Then it is forwarded towards the servlet again or a “.jsp” output can be generated. Following is a sequential order in which JSP pages are executed:
- A normal request is sent to the server by the browser.
- The server recognizes it as a JSP page and sends it to the JSP server for execution. The server recognizes this by locating the page with the extension as “.jsp”.
- The JSP is converted into a servlet.
- The JSP engine converts the servlet into executable class.
- When the output is obtained, it is converted into an HTML format and sent to the web browser.
Why and How Should We Use JSP?
JSP offers several features and describes why and how should we use JSP:
1. Translation: When a code is written, a Java Servlet file is created of a “.jsp” file. So when a regular code file is written with HTML and JSP tags, but the file extension recognized is “.jsp”, it is translated into a servlet file. This is the first step in the life cycle.
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2. Compilation: In this step, a servlet class previously available in the step is created into a servlet class file.
Ex: emp_jsp.java into emp_jsp.class
This compilation generally happens during deployment.
3. Loading: The class created gets loaded into the container, class loader.
4. Initiation: An instance of this class, an object is created. The container can manage one or more instances as per the need. So, as we have seen a class is called by an object in Java, similar things take place here. Init() and destroy() actions take place in this initiation phase.
5. Initialization: JSP init() method is called by the container and the initialization takes place.
6. Processing: All the services and requests are processed. GET() and POST() is processed.
7. Destroy: In this method, the instance created is destroyed as all the actions needed are processed and done.
Advantages and disadvantages
Below are the advantages and disadvantages:
Advantages
- Being an extension to Java servlet, it can use every feature of Java Servlet. Also, custom tags can be used along with it.
- There is no need to recompile JSP when changed. The changes automatically appear when run.
- The tags which are used are easy to understand and write.
- Supports Java API’s which can now be easily used and integrated with the HTML code.
- The results which are obtained are in HTML format, so they can be opened on any browsers.
- Customized JSP tags can be used. Ex: Tags with XML.
- Changes can be added to the business logic page rather than changing each and every page.
Disadvantages
- Though the database can be accessed with JSP, it is not easy to access the database as most of the servlet does not provide support.
- Being a servlet, if there’s an issue in the code, it becomes very hard to trace.
- JSP compilation time required is more than on a server.
How will this Technology Help you Grow your Career?
With advancements in every aspect of the IT field and in the online market. JSP, which is already playing a vital role, is going to be needed more and more for development and advancements. The database connectivity is the feature, which is going to be used far more thoroughly. People with minimum knowledge of HTML and JAVA can too use JSP, as it is very easy to handle and the calls made can be easily written with some help. Servlet works exactly like a JAVA class, so with all the features of JAVA, it makes JSP more likely to get used.
Conclusion
This is right now, and in the coming days will be needed more and more as everything is coming on online platforms. From regular fill-in/ fill-up registration forms to a complex quiz like structures or games, everything can be easily be developed with the help of JSP.
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