Transcript Master Degree Final Project

Point Of Sale(POS) J2EE Application
(POS J2EE Application with JRun)
< Master Degree Final Project >
Department : Computer Science
Degree : Master
Student : Woojin Choi
ID : 0426367
Topics
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Introduction of POS Application
System requirement
Application Map
Database Diagram
POS Component
POS Workflow using J2EE Design
HTML / JSP / Servlet / EJB in POS
J2EE Introduction (J2EE – J2EE API)
POS Application with J2EE
Enterprise JavaBeans (EJB)
POS Component Example
POS Security Mechanism
POS Scheduler
Supplementary Issues
Introduction of POS
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POS : Point of Sale
Business topic : Web based application for a customer to
check out the shopping easily and fast
Current Process : Customer comes in store -> Put the item to
shopping cart -> Wait to check out -> Clerk help to check out
Problem : Customers need to wait for a long time even the item
is simple
Solution : Put the clerk barcode scanning and checking out
systems to each shopping lane and allow for a customer to
check out the carts by himself
New system to solve the problem : POS J2EE Application
Benefits : Portable business solution / Integrated e-business /
Save the customer’s time / Down the store cost
System Requirement
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Server side
› Operating System : Win NT 4.0 / Win2K
› Web Server : IIS 4.0 / 5.0
› Application Server : JRun 3.0.2
› Database : MS SQL Server 7.0
Client side
› Browser : IE4.0 or higher
Application Map
Index.jsp
(Display shoppling cart)
Login.jsp
Authentication
Servlet
Products.jsp
Add/Edit/Delete
Shopping list
Checkout.jsp
Customized Error Pages
HTTP Error
Jrun Application Error
403.html
404.html
405.html
500.html
Loginerror.jsp
Loginerror.jsp
Logout.jsp
Scheduler
Database Diagram
POS Components
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Presentation Logic
› HTML
› JSP
› Login.jsp, customers.jsp, customer_profile.jsp, …
Interface Logic (Data Modeling)
› Servlet
› EditCustomer.class, DeleteCustomer.class,
AddShoppingList.class, …
Business Logic
› EJB
› Customer EJB, ShoppingList EJB, …
POS Workflow using J2EE design
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Presentation : JSP
Interface : Servlet
Business Logic : EJB
Benefits : Presentation logic doesn’t implement
business logics at all. Every business data is updated
through EJB or Servlets. Especially Servlet is
reponsible for data modeling for business logic as
interface between presentation and business logic.
JSP
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Servlet
EJB
Container
DB
HTML / JSP / Servlet / EJB in POS
HTTP on LAN
JSP
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Engine
Servlet
Container
EJB
Container
JDBC
HTTP
HTTP Server(HTML)
JRun
DB
Java 2 Enterprise Edition (J2EE)
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Defines a standard for developing multi-tier applications
› Vendors collaborate on standards and compete on
implementation
› All the pieces of the application are portable across
platforms and servers
Simplifies application development
› Developer focuses on application logic
› J2EE server handles complexity of lower level services
Component
› JSPs / Servlets / EJBs
API : Servlet / JSP / EJB / JDBC / JNDI / JavaMail / JMS / JTA
J2EE APIs
Servlets
› Standard API extending and enhancing Web servers
 Java Server Pages (JSP)
› Standard API for creating dynamic content using static templates
 Enterprise JavaBeans (EJB)
› Standard server-side component model
 Java Database Connectivity (JDBC)
 JavaMail
 Java Naming and Directory Interface (JNDI)
 Java Message Service (JMS)
 Java Transaction API (JTA)
*) POS system : Servlet / JSP / EJB / JNDI / JDBC
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POS Application with J2EE
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Provides complete implementation of J2EE
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POS Application
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Servlets 2.2
JSP 1.1
EJB 1.1
JNDI
JMS
JDBC
JTA/JTS
JavaMail
Servlet 2.2
JSP 1.1
EJB 1.1
JNDI
POS Application Work Flow
› Presentation : JSP
› Interface : Servlet
› Business Logic : EJB
Enterprise JavaBeans (EJB)
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Server-side component model allowing developers
to concentrate on business logic
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EJB server handles complexity of lower level
services
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Component life cycle
State management
Persistence
Multi-threading
› Connection pooling
› Transaction management
› Security
EJB API guarantees components to be portable
across EJB Servers
Entity Beans
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Used to
› Represent a business entity (like a row in a
database table)
› Provide standard access and validation for
business entities
Persistent (live beyond server lifetime)
› Usually represent data in a database
Examples
› Customer, Product, Employee, ...
Entity Beans
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Bean Managed Persistence (BMP)
› Developer writes persistence code
Container Managed Persistence (CMP)
› EJB properties are mapped to database columns
› Persistence code automatically generated by EJB
container
Implements javax.ejb.EntityBean
Session Beans
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Used to
› Manage processes and tasks
› Model the workflow of Entity beans
› Retrieve and update data that can't be adequately captured
in an entity bean
No persistent state
Example
› Order a product
› Check out the shopping cart
› Reservation
Session Beans
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Stateful Session Bean
› Maintain a state between method invocations
› Store properties as instance variables
› Expose methods to manipulate properties
Stateless Session Bean
› Do not retain information between method invocations
› Each method is completely independent
› Client passes needed information as parameters to the
method
› Participate in instance pooling
› Greatest scalability
› Many clients share limited number of instances
Implements javax.ejb.SessionBean
Home / Remote Interface
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Home Interface
› Defines methods to create (obtain), find, or remove
a Bean Instance on behalf of the client
› Extends javax.ejb.EJBHome
Remote Interface
› Defines the bean's business methods
› Extends javax.ejb.EJBObject
Packaging the Bean in a JAR File
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Includes:
› Bean class
› Remote interface
› Home Interface
› Deployment descriptor
(ejb.xml)
ShoppingListHome.class
ShoppingList.class
ShoppingListEJB.class
ejb.xml
Deploy Tool
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Deploy Tool(Macromedia KAWA, J2EE deploytool) generates
stub classes and object classes
Deploy Tool uses jar file and generates necessary classes for
EJB server
Stub classes
› Downloaded to a client dynamically at run time
› Used by client
Object classes
› Implement all corresponding interfaces
› Used by EJB server
EJB Conceptual Architecture
lookup(“Customer")
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JNDI Server
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InitialContext
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EJB Server
create/find
EJB Home Stub
Home Interface
EJB Home
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Home Interface
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getList( )
EJB Object Stub
Remote Interface
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EJB Object
Remote Interface
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EJB Class
Development Process EJB
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Developer
› Home Interface
› Remote Interface
› EJB class
› Support classes
Deployer (Deploy tool)
› Packaging Interfaces, EJB class, and support classes
› Deploy the packaged EJB (jar file)
Server
› Implement EJB
EJB
Devloper
CustomerHome.class
Customer.class
CustomerEJB.class
ejb.xml
EJB Servers
POS Component Example
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Add, remove, and display a customer shopping list
ShoppingListSession
Display
Index.jsp
DB
Add Remove
ShoppingCart
Table
AddShoppingList
RemoveShoppingList
Display all
shopping list
from EJB
Form action to
add / remove
shopping list
Capture the
Shopping list id
Call bean
method to be fit
with each action
Implement get,
add, remove
shipping list
methods
Select, update,
delete shopping
list from
ShoppingCart
table
POS Security Mechanism
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Form Based JRun application security based on J2EE
User / Group / Role
Protect entire application JSPs / Servlets / EJBs
*) DatabaseAthentication.java to verify user using DB
POS
Login.jsp
Authentication*
Servlet
Loginerror.jsp
HTML
JSP
Servlet
EJB
Other Resources
POS Scheduler
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Jrun provides a Scheduler servlet to execute actions
at specified times
Scheduler servlet : allaire.jrun.scheduler.CronService
Defines the servlet in web.xml
Application defines Schedule.ini for the service
Schedule.ini includes the rule and the requests to be
scheduled
* If this service is used in application, this application
is not potable because JRun added this service.
Web.xml sample for scheduler
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<servlet> defines the service </servlet>
<servlet>
<servlet-name>POSScheduler</servlet-name>
<servlet-class>allaire.jrun.scheduler.CronService</servlet-class>
<display-name>POSScheduler</display-name>
<description>Scheduler for POS System</description>
<init-param>
<param-name>schedfile</param-name>
<param-value>C:\JRun\3.0\servers\default\pos-app\schedule.ini</param-value>
</init-param>
<init-param>
<param-name>logfile</param-name>
<param-value>C:\JRun\3.0\servers\default\pos-app\scheduler-log\pos-scheduler.log</param-value>
</init-param>
<load-on-startup/>
</servlet>
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Except those bold tags, developer can give any name or file
Schedule.ini Example
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Schedule.ini is defined in web.xml
<init-param>
<param-name>schedfile</param-name>
<param-value>C:\JRun\3.0\servers\default\pos-app\schedule.ini</param-value>
</init-param>
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Developer can use any file name on that
Schedule.ini example
# This is the ini file for JRun scheduler
# Scheduler checks the shopping cart table every ten minutes and updates the shopping cart status.
# If the shopping cart items are found to be older than 2hr, those will be deleted.
# Those items to be older than 2hr are supposed to be not in the cart or customer left the store without checkout.
0 0,10,20,30,40,50 * * * * http://localhost/pos/servlet/SchedulerForShoppingCart
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Scheduler runs this servlet every ten minutes
Supplementary Issues
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Physical Security Mechanism
Barcode scanner integration(physical)
Credit card process integration(physical)
Business data exchange using XML