OCEJWCD - 1. Introduction to Java Servlets

OCEJWCD (SCWCD) - 1Z0-899 - Web Component Developer Certification

1.1    Describe web applications, CGI, and the role of Java

Web applications are the software app that runs in a web browser.

CGI is Common Gateway Interface. It was the technology commonly used as a standard for dynamic web programming until they were replaced by servlets.
They are based in a helper app that work with the server (written generally in Perl) and serves dynamically generated data in an HTML static page.

Role of Java

JavaEE application Server

Servlets technology serves dinamically data to the client usign JSP (java server pages). 

Servlets Container:

• Communications support (handle the request and response)
• Lifecycle management (init/service/destroy)
• Multithreading support (1 thread per rquest)
• Declarative security (in DD)
• JSP support

1.2    Describe benefits of Java servlet technology

• Servlets have the advantages of portability and security that java technology provides.
• Servlets are more efficient , CGI program needs to load for every request, but servlets are called first time they remain active in the servlet memory, for every request a new thread is created.

1.3    Create a simple Java Servlet

Example of Servlet:


Notes to create web applications in Eclipse:

• Create web project : Select new project->web->dynamic web project
• Create servlet class: In our scr package create a new: Servlet. It creates a class with autogenerated methods to define a servlet.
• Create Deployment Descriptor: Web Project -> rightClick -> JavaEE Tools -> Generate Deployment Descriptor Stub.

1.4    Define three-tier architecture


Three-tier architecture is a software architecture, every layer is developed and maintained as independent modules.

1.5    Define Model-View-Controller (MVC) architecture

Model view controller is an architectural pattern for implementing web applications.

OCEJWCD (SCWCD) - 1Z0-899 - Web Component Developer Certification