Servlets and HTTP Servlets

Servlets	Http Servlets
It protocol independent	This is protocol dependent(HTTP).
Created by extending GenericServlet Class	Created by extending HttpServlet class
Overrides service() method to process client request and to generate response	Override doGet/doPost (or doGet, doPost, doPut, doDelete etc.) method(s) to process client request and to generate response
Method service() is invoked for all incoming requests.	Specific method is invoked one of these; doGet, doPost, doPut, doDelete, doTrace etc. depending on the request’s method.

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Using HyperSQL (HSQLDB)

HSQLDB is a portable RDBMS implemented in pure java. It can be embedded with your application as well as can be used separately. It is very a small database that supports almost all features of the standard database system. It comes with small jar file that can be found in lib folder. The HSQLDB jar package is located in the /lib directory of the ZIP package and contains several components and programs. Core components of jar file are : HyperSQL RDBMS Engine (HSQLDB), HyperSQL JDBC Driver, Database Manager, and Sql Tool. Installing and Using Download: download latest release of HyperSQL database from http://hsqldb.org website and extract it. You will see following contents. Here "bin" directory contains some batch files those can be used to run a swing based GUI tool. You can use runManagerSwing.bat to connect to database, but database must be on before running it. Directory lib contains File hsqldb.jar . It is the database to be used by you. Running database First ...

In Process Mode of HSQLDB in web application.

If you want to use the database into your web application, you can use the HSQLDB in In_Process mode. In this mode, you can embed the HSQLDB into your web application and it runs as a part of your web application programm in the same JVM. In this mode, the database does not open any port to connect to the application on the hosing machine and you don't need to configure anything to access it. Database is not expposed to other application and can not be accessed from any dabase tools like dbVisualizer etc. In this mode ,database will be unknown from any other person except you. But in the 1.8.0 version, you can use Server intance for external as well as in process access. To close the databse, you can issue SHUTDOWN command as an SQL query. In the in-process mode, database starts from JDBC with the associated databse file provided through connection URL. for example DriverManager.getConnection("jdbc:hsqldb:mydatabase","SA",""); Here myd...

How to handle values from dynamically generated elements in web page using struts2

Some time you will see the form containing the button " Add More " . This facility is provided for the user to get the values for unknown number of repeating for some information. for example when you are asking to get the projects details from user, you need to put the option to add the more project for the user since you don't known how many projects user have. In the HTML form, you repeat the particular section to get the multiple values for those elements. In Html page , you can put the option to add new row of elements or text fields by writing the java script or using JQuery API. Now, the question is that how to capture the values of dynamically generated text fields on the server. Using the servlet programming you can get the values by using getParameters() method that resultants the array of the parameter having the same name. But this limit you to naming the text fields in the HTML form. To ally this approach, you have to take the same name for t...

Programming For Future

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