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Idiot’s guide to Web Environment-JSP
Idiot’s guide to Web Environment-JSP
JSP-Java Server pages is a server side scripting language. Did not comprehend what that means? Well, in lay man’s language, jsp is a technology for creating dynamic web pages, which uses the traditional Http approach of request-response, with all the business functionality carried out at the server side using java.
Still having a dilemma? Let us begin with the basics. To view information over the internet, we require an interface, which we call a browser. This browser is nothing but an html parser that displays the .html or .htm file sent by a web server. Now, html is a mark-up language designed for this sole purpose of displaying the web content. Html has fixed tags that help in the process and also has the important tags or even CSS for visually pleasing display of information. Now what is google? It is that magic box(actually a search engine!) which will run around the world asking everyone on the internet and bring you the best answers to your query. You need to have
special web hosting for hosting your JSP files, you can use Bluehost coupons to save your money easily. Let us now understand a web server and then we finally move on to java server pages. A web server is a computer hardware or software which runs at a remote location, and responds to a request sent in by the client. Whenever we click a button or view a page or do any activity on a web page, the data displayed is provided by the web server processing our request. Html, CSS and Javascript form a trio where Javascript is basically used for client-side scripting without the necessity of invoking a server’s help. It can be used to display alerts, for form validation and so on and so forth. So now, where does JSP come into picture? To provide better functionalities, to have speed, security along with reliability, scalability, interoperability and many other specifications, different languages for web development came into existence,
each having its unique use, advantage and depending on the requirement, selection of such a technology can be made. To name a few popular: php , asp .net, vb .net, jsp. Today, we look at JSP. In plain text, jsp is a java based technology that operates at the server side and aids the server in giving an apt response back to the client. JSP is java embedded in html. You simply write java code into html file by using some special characters to mark the beginning and end of the jsp code. This code is perused by the server and the processed result is sent back. A jsp file has a .jsp extension. All the features of java, like its security, objectoriented approach, and automatic garbage collection are available in jsp because the jsp code is compiled by a java compiler running on the server machine. We will soon understand thejsp life-cycle and the role a servlet plays in it.
Basics of JSP [Java Server Pages] Those who are familiar with java will have absolutely no problem with coding in jsp. For others, you need to know java to work with jsp! Let us understand it in the simplest way possible. Start in by taking .html file with the required forms, gui, etcetera. Then code in your jsp using the jsp start and end tags. A jsp code can be embedded anywhere in the html file. You can write the jsp code in the head, in the body or between the head and the body. No restrictions at all!A jsp code can have 4 type of tags: 1) Directives: They serve the primary purpose of importing the java packages. 2) Declarations:
They are used to make declarations likeintdefault_value=5, double volume=216.231, etc. 3) Scriptlets: The scriptlets contain your java business logic. 4) Expressions: Expressions let us use the value of the JSP variables at different places in the html code; especially useful for displaying such values. Important thing to note here in scriptlets is that we do not write classes but directly start coding into the scriptlets.
Servlet and jsp life cycle
By now, we know that jsp is java embedded into html. Servlet is exactly its opposite. It is html embedded in java. We will not look into its details, but servlet occupies a pivotal place in jsp based environments.
Fig: JSP Life-Cycle Jsp life-cycle starts with conversion of jsp into servlet, i.e. into a .java file. From there on, the jsp lifecycle is exactly like that of servlet’s. The .java file is compiled by a java compiler to give a .class file which when executed, the servlet is first initialized, then the service method possesses the business logic to be processed and finally it is destroyed after an apt response has been sent back to the client.
Some important tips U can use frameworks like the Adobe Dreamweaver for building your jsp pages, where the html UI can be built using the framework but the jsp technology code will have to be written in. Using a java editor like JCreator or EditPlus and then migrate the code, is also a viable option.
Never ever write the business logic injsp. This is the first and foremost thing mentioned by Oracle; and rightly have they mentioned so. If the business functionalities are in jsp, then it becomes extremely difficult to port such a webpage or website, say from desktop to smartphone. Though a bit tedious, a more efficient and secure method would be to direct a jsp page to a servlet, which could perform the desired actions (like accessing a database), just like a jsp page would have. Jsp is slower than php, but certainly more secure. If you are planning to deploy jsp on free web hosting sites, it may not be possible. The reason is that most of these free websites do not support jsp. Even if you plan to buy a server, it has to be a dedicated one, because a distributed server might not work as you are not given access to its root folder, thus making it impossible to add jar files or difficult to make changes. It would be
better to buy a dedicated server, and having an online database is advisable. You are now set explore jsp and create your own fervent world! Read Full Article: http://www.teechworld.com/idiots-guide-toweb-environment-jsp/