JEE / J2EE
The Java Platform, Enterprise Edition (JEE) is a specification of software components and services of applications programmed in Java. The spec serves the development of modular, multilayer applications and defines interfaces so that software components of different developers are interoperable.
JSP
Java Server Pages (JSP) is a technologie developed by Sun Microsystems. In general, it is used to generate dynamic HTML and XML output by a web server. In JSP Java code can be implemented and so the website which is to generate can contain static HMTL code as well as dynamic elements.
Java Server Pages are converted by a special JSP compiler to Java classes during runtime. These one are handled by the JEE runtime environment. This technology is comparable with other applcations that are dynamic and executed on server-side, like for example Active Server Pages (ASP, Microsoft) or PHP. In comparison to PHP, JSP offers fundamental advantages concerning ressource consumption and modular design.
JSF
JavaServer Faces (JSF) are a standardized framework that is adopted for the development of user interfaces in web applications. The framework is based on Java Server Pages. It contains many web elements, like for example different input fields, buttons, selection lists, etc., that can be used in a very simple way to ease the data exchange from the user interface to the business logic.
Further parts of the framework are:
- Localization of the application
- Validation of input data
- Navigation rules to control the user navigation
- Use of converters
Facelets
Facelets are a framework that enables the use of JSP elements during the lifecycle of JavaServer Faces. That are for example control structures in the graphical user interface (loops oder simple if-then-else constructs) which else couldn't be used within JSF.
Log4j
Because of the complex configuration of today's applications and the world wide use of external frameworks it is indispensible for professional applications to log the system state. Therefore the log4j framework lends itself. For every log entrance can be defined a message, the timestamp and a logging classification. This could be for example:
- DEBUG: Remarks about current code position, for example "enter method x" or "return value = y".
- INFO: Remark about data converting like "PDF successful generated".
- WARNING: Errors during data converting. The requested working step can be executed, but the converted data is possibly affected, for example "data for field x was too long, however PDF created".
- ERROR: Errors during data converting, the requested working step can't be executed, for example "PDF couldn't been saved, I/O error".
- FATAL: Critical error, application is no more executable and has to be exited, for example "no connection to database".
In the configration of log4j can be defined, which logging methods are used. Depending on configuration for example daily changing log files can be created in the log directory of the servlet container tomcat. Over the global log level can be defined which messages are logged in the log file.