Download Lecture2

CS441
CURRENT TOPICS IN
PROGRAMMING
LANGUAGES
LECTURE 2
George Koutsogiannakis / Summer 2011
1
Overview of Java EE
• Past
– discreet APIs allowed building of complex
enterprise solutions.
• EE
– combines most of the above and new APIs
into one enterprise bundle of tools and APIs.
2
Distributed Multi-tiered
Applications
• Enterprise applications can be distributed in various servers located in
different locations.
• They are comprised of various tiers i.e.:
– Client Tier (Presentation Tier): Consists of components that run
on the client machine. Can be applets working in a Browser or
application programs.
• These components can communicate with a Web Server using
HTTP protocol to send requests and receive responses.
Or
• They can communicate via another protocol with the Business
Tier applications.
3
Distributed Multi-tiered
Applications
– Web Tier: Consists of the Web Server and applications that run in the
web server using special containers that the web server must have, i.e.
Servlet container.

The Web Server can be Jakarta Tomcat or any other Web Server that has
the proper containers.
 The term container refers to special executable programs
(sometimes called engines) that a server can have . These
containers are capable of recognizing the particular type of java
program that the server is interfacing with.
4
Distributed Multi-tiered
Applications
– Business Tier: Components that run on distributed servers. Those
servers can be RMI (Remote Method Invocation) servers or
Application Servers with Enterprise Java Beans.
• Notice that either the web server applications act as client to
the remote servers (to RMI or Application Servers)
• Or, that the Client Tier can directly contacts these distributed
services via some protocol (without going through the web
server).
• The application servers are available through various vendors
including Sun Microsystems (on April 20, 2009 Oracle
announced that it is acquiring Sun MS- the deal is still pending
closure).
5
Distributed Multi-tiered
Applications
– Enterprise Information System Tier (Data Tier): Data bases
that run on legacy machines and have various data that the
customer at the Client Tier needs.
• The Enterprise hires developers (and other software
engineers) and obtains tools to establish the tiers.
– A number of developers are working on the various tiers.
Developers have specialized experiences based on the tier they are
working with.
• Their experience also is tool depended. Some are familiar with NetBeans,
others with Websphere , others with .NET tools (Microsoft) and so on.
6
Distributed Multi-tiered
Applications
– Other software engineers are responsible for the
• Temporary deployment in the servers and the testing of the various
parts of the enterprise application.
• The final deployment in the servers.
7
Example of Past Implementations
• Web Server: Jakarta Tomcat
• JDK SE:
– SWING AND AWT Graphical Components
– JDBC (Java Data Base Connectivity)
– RMI (Remote Method Invocation)
– RMI over IIOP (RMI over Internet Inter-Operability Protocol)
– Servlet and Java Server Pages API could be added to SE
– Java Email API couled be added to SE
– Java Messaging Services API could be added to SE
– Java Beans API
8
3-TIER ARCHITECTURE- Example from
CS441 Project 2 Spring 08
• THE BASIC BANK SERVICES ARCHITECTURE IS:
CLIENT
GUI
INTERNET
BROWSER
WEB
SERVER
Customer
Accounts
Servlet,
Users Servlet,
Updated
Selections
Servlet e.t.c,
Applet, html
files, images
RMI SERVER
/JDBC
DATA
BASE
RMI SERVER
/ JDBC
PRESENTATION TIER
WEB TIER
AND
BUSINESS
RULES TIER
DATA TIER
9
3 Tier Example discrete API
usage
•
•
•
•
The Web Server was Jakarta Tomcat
The Client GUI was an Applet
The business rules were applied via servlets, jsp
The RMI server demonstrated distributed applications (not necessarily
collocated with the web server).
• The distributed services used JDBC to connect to respective databases
• Client Request -> Web Server-> proper servlet (servlet was a client to
a RMI server) -> RMI server JDBC query->Database
• Database query result (data)-> RMI server-> corresponding servlet
(its client)-> response to web server servlet container-> HTTP
response packets to client Applet
10
Revised 3 tier architecture using Enterprise
Java Beans and Application Servers
CLIENT
GUI
INTERNET
WEB
SERVER
Application
Server EJBs
Servlets/
Java
Server
Pages
DATA
BASE
Application
Server EJBs
BROWSER
Distributed Applications
PRESENTATION
TIER
WEB TIER
BUSINESS
RULES
TIER
DATA
TIER
11
Revised 3 tier architecture using Enterprise
Java Beans and Application Servers
• Notice that the Communication between the
client and the service needed can also be
direct by passing the web tier and going
through a private network:
CLIENT
NETWORK
APPLICATION
SERVER
12
Revised 3 tier architecture using Enterprise
Java Beans and Application Servers
• Quite often the Application Server (such as
GlassFish) contain the web server and the
database.
– Note that GlassFish used to be called Sun
Application Server
13
Multi Tier
• Multi Tier architectures can be built where
additional servers become part of the
architecture such as:
– Firewall server: handles all incoming traffic
from the Internet, helps protect the rest of the
system from attacks.
– Local Balancer: Distributes transactions to
various servers.
14
Multi Tier
– Transaction Processing Monitor: Handles
incoming requests and forwards the request to
the proper application server.
• The above 3 types of servers define what is
called PortalServices.
15
Java EE
• Integrates all API s and tools needed for
establishing multi-tiered applications.
– Combines Web Server and Application Server
into Java EE Server.
– GUI components for the client tier are created
using Java Server Faces technology
• Graphical Components are created on the server side
and rendered as an object in a mark up language
(HTML, XML etc.)
16
Java EE Tiers
CLIENT TIER- Java Application/Dynamic HTML
pages/Java Script / Java Bean components
Java EE
Server
Web Tier (Web Server)
Enterprise Java Beans
(Application Server)
Databases
17
Naming Services
• Distributed Services Need to be discovered.
• For Example: RMI provides a simple
server called rmiregistry where remote
servers can register their remote objects.
– A client first contacts the registry to get a
reference to the remote object (i.e. the name of
the server, the port number that the server
listens, the remote object id).
18
Naming Services
• Java EE includes the Java Naming and
Directory Interface API ( JNDI).
– This API allows clients to discover remote
objects (provided those remote objects have
registered with the JNDI)
19
Java EE Security
• Java EE allows security to be defined at the time of
deployment of the application.
– In discrete APIs security needs to be defined with special policy
files and certificates. In addition separate programs are needed by
using the various Security APIs.
– Cumbersome and application specific.
• Java EE utilizes the various Security APIs in an integrated
approach to provide security settings at the time of
deployment.
– Uses the Java Authentication and Authorization Service.
20
JEE APIs
• Other APIs included in JEE:
– JDBC (Java Data Base Connectivity)
– Java Servlets and Java Server Pages (JSP)
– Java Server Faces
– Java Enterprise Beans
– Java Message Service
– Java Transactions
– Java Email
– JavaBeans Activation Framework
– Various APIs for Web Services implementation
21
Types of Tasks in an Enterprise
– Purchasing of software from Java EE vendors who have
implemented the Java EE server.
– Tool providers for development tools and also packaging tools (i.e.
NetBeans Development tool).
– Development of Java Enterprise Beans, web components
(applets,servlet, jsp other programs, java applications for client and
other programs)
– Assembly of the application into an EAR file.
– Temporary Deployment of the application by an administrator into
the server(s).
– Testing
– Final Deployment into the server(s).
22
JAVA GRAPHICS
• Let us revert to some basic Java Graphics
before we return to the topics of server side
Java.
• Graphics should be understood before the
concept of Java Server Faces as a substitute
for graphical components is discussed or
• Before the usage of NetBeans to create
graphical components is discussed.
23
JAVA GRAPHICS BASICS
• JAVA CONCEPTS INVOLVED
– AWT & SWING APIs PROVIDE
• TOP CONTAINERS OBJECTS
• COMPONENTS OBJECTS
• SUB CONTAINERS OBJECTS
• LAYOUT MANAGERS OBJECTS
• PAINT / UPDATE/ REPAINT METHODS FOR EACH
CONTAINER
24
Java Graphics
• Involves knowledge of various containers
– i.e. Top Containers: JFrame, JApplet, JDialog
– Other containers can be dropped into top containers:
• JPanel
• JInternal Frame
• Other components can be dropped in a Container i.e.
–
–
–
–
JTextArea
JTextField
JButton
JEditorPane ( a component that allows html files to be displayed plus other text
formats).
25
Java Graphics
• Involves knowledge of Layout Managers:
–
–
–
–
FlowLayout manager (default)
BorderLayout Manager
GridLayout Manager
GridBagLayout Manager
• GridBagLayout is the one Layout manager
used for professional presentations.
26
BorderLayout Manager
• Divides Screen up to 5 Areas:
NORTH
WEST
CENTER
EAST
SOUTH
27
BorderLayout Manager
• Set up the top Container first by extending
your class to inherit the container:
public class MyClass extends JFrame
{
//call super class’ constructor to pass a name for the Frame
public MyClass()
{
super(“My Frame Name”);
28
BorderLayout Manager
• Usage:
Container c= getContentPane();
c.setLayout(new BorderLayout(5,5));
JButton b1=new Jbutton(“First Action”);
c.add(b1, BorderLayout.NORTH);
……………………………………………………
29
EVENT HANDLING
•
•
•
•
EVENT LISTENER INTERFACES.
EVENT OBJECTS.
EVENT ADAPTER CLASSES
TECHNIQUES FOR GENERATING
EVENTS.
30
EVENT HANDLING
EVENT
SOURCE
EVENT
OBJECT
EVENT
LISTENER
31
Event Handling
• Create component object
• Register component object with the event
handler object.
• Create an event handler class that
implements the Event Listener interface that
goes with the particular component
– Implement the proper method of the Even
Listener Interface.
32
MORTGAGE CALCULATOR –
APPLICATION VERSION
•
•
•
•
•
JFRAME AND BORDER LAYOUT MANAGER
USAGE OF JPANEL AND BOX MANAGER.
JTABLE COMPONENT.
MODEL/ VIEW / CONTROLLER DESIGN PATTERN
DEMONSTRATION OF EVENT HANDLING
– USING ANONYMOUS INNER CLASS
– USING AN INNER CLASS
– USING A SEPARATE FILE
• ANOTHER VERSION USES GRID BAG LAYOUT MANAGER
33
STUDY GUIDE
• Read Web Based Applications
Development: chapters 2 and 3
• Read Java EE Tutorial: Part II Chapter 3.
• Study Mortgage Calculator examples for
Graphics.
34