Grammaroriented Object Design Case Study: Ebazaar

1
Grammar-oriented Object DesignCase Study
E-bazaar
Maharishi University of Management

• Ali Arsanjani
• Landung Wahana
• Nyo Maw
• Rameshwor Kunwor
• Purnima Shreshta
• Sharad Acharya
• Keith Levi
• Software Architecture Group
• Computer Science Department
• Maharishi University of Management

2
Aim

• Train students for industrial strength projects
• Provide expertise in latest technologies and
  methods
• Build a team here at MUM that could develop
  software for outside clients via subcontracting,
  etc.
• Bring flow of wealth to Fairfield university and
  faculty and students
• Provide input into our courseware
• Create technical reports and experience reports
  to increase expertise and knowledge base of
  object and component-oriented methods and
  technologies

3
Background

• The E-bazaar project at Maharishi University of
  Management uses Grammar-oriented Object Design
  (GOOD), an evolved form of object-oriented
  software engineering that is aimed at building
  component-based software architecture for
  business systems using a dynamic configuration,
  dynamic collaboration and adaptive object model
  approach to increase flexibility, reuse and
  decrease maintenance costs and decrease time to
  market.We utilize a new paradigm for
  component-based software development to construct
  a Rapidly Re-Configurable Architectural Style.
• The functional characteristics of E-bazaar are
  aimed at creating 1. An online order-entry
  system with a generic component-based
  architectureto allow adaptive modifications with
  minimal maintenance costs2. A community and an
  e-marketplace for business-to-business
  transactionsThese will be implemented in two
  phases. The e-bazaar project will be implemented
  using a J2EE reference model and phase 2 will
  utilize Web Services.

4
Project Path

• August 2001 November 2001
• 15 Members started, left with 7
• Started reading literature
• on GOOD and Enterprise Component, Java, EJBs, XML
• Implement minimal functionality end-to-end
• Each person responsible for their component
• Shopping Cart
• Order Management
• Customer Management
• Product management
• E-Bazaar Component
• Externalize business flow in E-bazaar component
• Use open source development tools
• Orion App Server, ANT, Java JDK (IDE VAJ),
  EditPlus

5
Project Path

• Implement Enterprise Component Pattern in each
  component
• Provided uniform development paradigm and
  guidance
• Deployment and integration issues delayed project
  for 2 weeks
• Lessons team learned
• Integration should be continuous and upfront
  rather than later

6
The Design of a Business Complier

• Every business domain has a domain specific
  language that
• defines the components within it,
• their business flow (of data and messages) and
• their intent as it ties back to the business
• Capture this domain knowledge in a grammar
• An application can be composed by assembling
  components and defining a grammar of how they
  speak to one another
• Thus, components are decoupled and changes can be
  made to the application as a whole in an easier
  fashion maintenance costs are lowered (see
  section on adding functionality)
• New paradigm of software engineering
  Grammar-oriented Object design (GOOD)

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Grammar-oriented Object Design

• Every program uses a set of terminals
  nonterminals and tokens (events) based on
  production rules written as a domain-specific
  langauge within the domain to assemble its
  components (nonterminals)
• Actions are executed within the grammar as events
  (tokens) are detected
• http//www.arsanjani.org/GOOD/

8
Subsystems
9
Team Structure

• Each subsystem assigned to a person or group of
  people
• Asked to implement thin slice then enterprise
  component pattern

10
The DTD

• lt?xml version"1.0" encoding"UTF-8"?gt
• lt!ELEMENT Action EMPTYgt
• lt!ATTLIST Action
• name CDATA REQUIRED
• type (adaptor command ui) REQUIRED
• info CDATA REQUIRED
• gt
• lt!ELEMENT Event EMPTYgt
• lt!ATTLIST Event
• name CDATA REQUIRED
• type (request response) REQUIRED
• info CDATA REQUIRED
• gt
• lt!ELEMENT Grammer (Production)gt
• lt!ELEMENT Non_Terminal EMPTYgt
• lt!ATTLIST Non_Terminal
• name IDREF REQUIRED
• gt
• lt!ELEMENT Production (Event Action
  Non_Terminal)gt

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The Grammar for E-bazaar

• lt?xml version"1.0" encoding"UTF-8"?gt
• lt!DOCTYPE Grammer SYSTEM "http//www.arsanjani.org
  8080/ebz/ec/xml/grammar_2.dtd"gt
• ltGrammergt
• ltProduction name"OnlineShopping"
  type"Sequence" info"optional"gt
• ltNon_Terminal name"SignOn"/gt
• ltNon_Terminal name"Presentation"/gt
• ltNon_Terminal name"SignOut"/gt
• lt/Productiongt
• ltProduction name"SignOn" type"Sequence"
  info"optional"gt
• ltEvent name"Login" type"response"
  info"optional"/gt
• ltAction name"LoginChallenge" type"ui"
  info"com.ebazaar.customermanagement."/gt
• ltNon_Terminal name"SignOnType"/gt
• lt/Productiongt
• ltProduction name"SignOnType" type"Choice"
  info"optional"gt
• ltNon_Terminal name"CurrentUserSignOn"/gt
• ltNon_Terminal name"NewUserSignOn"/gt
• lt/Productiongt

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The Grammar for E-bazaar

• ltProduction name"CurrentUserSignOn"
  type"Sequence" info"optional"gt
• ltEvent name"LoginSubmit" type"request"
  info"optional"/gt
• ltAction name"LoginVerify" type"command"
  info"com.ebazaar.customermanagement.security."/gt
• ltNon_Terminal name"SignOnResponse"/gt
• lt/Productiongt
• ltProduction name"SignOnResponse" type"Choice"
  info"optional"gt
• ltNon_Terminal name"SignOnOk"/gt
• ltNon_Terminal name"SignOnNotOk"/gt
• lt/Productiongt
• ltProduction name"SignOnOk" type"Sequence"
  info"optional"gt
• ltEvent name"SignOnOk" type"response"
  info"optional"/gt
• ltAction name"LoginOk" type"adaptor"
  info"com.ebazaar.customermanagement."/gt
• lt/Productiongt
• ltProduction name"SignOnNotOk"
  type"Sequence" info"optional"gt
• ltEvent name"SignOnNotOk" type"response"
  info"optional"/gt
• ltAction name"LoginNotOk" type"adaptor"
  info"com.ebazaar.customermanagement."/gt
• ltNon_Terminal name"SignOn"/gt
• lt/Productiongt

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The Grammar for E-bazaar

• ltProduction name"Presentation" type"Sequence"
  info"mandatory"gt
• ltEvent name"Presentation"
  type"response" info"mandatory"/gt
• ltAction name"PresentationPage" type"ui"
  info"com.ebazaar.productmanagement."/gt
• ltNon_Terminal name"VisitorOption-
  2"/gt
• lt/Productiongt
• ltProduction name"VisitorOption-1"
  type"Choice" info"mandatory"gt
• ltNon_Terminal name"Search"/gt
• ltNon_Terminal name"Selection"/gt
• ltNon_Terminal name"SignOut"/gt
• lt/Productiongt
• ltProduction name"Search" type"Sequence"
  info"mandatory"gt
• ltEvent name"Search"
  type"response" info"mandatory"/gt
• ltAction name"SearchResult" type"ui"
  info"com.ebazaar.productmanagement."/gt
• ltNon_Terminal name"VisitorOption-
  2"/gt
• lt/Productiongt

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The Grammar for E-bazaar

• ltProduction name"VisitorOption-2" type"Choice"
  info"mandatory"gt
• ltNon_Terminal name"Search"/gt
• ltNon_Terminal name"Selection"/gt
• ltNon_Terminal name"SignOut"/gt
• ltNon_Terminal name"AddProduct"/gt
• ltNon_Terminal name"ShowCart"/gt
• ltNon_Terminal name"CheckOut"/gt
• ltNon_Terminal name"SaveCart"/gt
• lt/Productiongt

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The Grammar for E-bazaar

• ltProduction name"SaveCart" type"Sequence"
  info"mandatory"gt
• ltEvent name"SaveCart"
  type"response" info"mandatory"/gt
• ltAction name"SaveCart" type"ui"
  info"com.ebazaar.productmanagement."/gt
• ltNon_Terminal name"ShopperOption-
  1"/gt
• lt/Productiongt
• ltProduction name"Selection" type"Sequence"
  info"mandatory"gt
• ltEvent name"BrowseProductItem"
  type"response" info"mandatory"/gt
• ltAction name"BrowseResult" type"ui"
  info"com.ebazaar.productmanagement."/gt
• ltNon_Terminal name"VisitorOption-
  2"/gt
• lt/Productiongt
• ltProduction name"AddProduct"
  type"Sequence" info"mandatory"gt
• ltEvent name"AddProduct"
  type"response" info"mandatory"/gt
• ltAction name"AddProduct" type"ui"
  info"com.ebazaar.shoppingmanagement."/gt
• ltNon_Terminal name"VisitorOption-2"/gt
• lt/Productiongt

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In your JSP page

• ltform method"post" action"/ebz/ebazaarapplicatio
  ngateway"gt
• ltinput type"submit" name"eventToken"
  value"OnlineShopping"gt
• lt/formgt

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Shopping Cart SubsystemClass-Diagram
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Shopping Cart SubsystemMain Classes

• Business Objects
• -CCartItem-represents each item in Cart
• -CShoppingCart-represents cart in which items are
  added or removed.
• Servlets
• -ShoppingCartServlet- for adding item to cart
• -UpdateCartServlet- for updating item of cart.
• -DeleteCartServlet-for deleting item from cart.
• JSPs
• -ebz_ShoppingCart- that shows the contents of
  cart with options to update, delete and checkout.
• Other helper classes.

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Shopping Cart SubsytemGeneral Workflow

• User selects product and adds to cart.
• UserID and ProductID of the selected product are
  passed to the subsystem as parameter from jsp
  page.
• This userID and ProductID along with quantity of
  product is stored in database.
• Once the product is added to the cart, it can be
  deleted and updated until CheckOut is performed.
• When user checks out, this subsystem will handle
  the control to OrderManagement Subsystem and
  passes along the cart through session.

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Shopping Cart SubsystemDatabase Design

• Database design is simple
• Consists only one table with fields UserID,
  ProductID and quantity.
• UserID is foreign key from User table, ProductID
  is foreign key from product table.
• UserID and ProductID combinedly forms primary key
  for the table.
• May be one more field is required.

21
Shopping Cart SubsystemCurrent Status and
Possible Modifications

• Current Status
• 1. Presently adding, deleting and updating of
  cart is reflected to database in each and every
  step as in amazon.com.
• 2. At present, none of the business rules are
  applied to system.
• 3. At present, database design doesnt reflect
  completed and uncompleted orders, i.e. items will
  remain in cart even after placing order.

• Future Modifications
• 1. Adding deleting and updating of cart can be
  stored in session and is stored in database only
  after Checkout.
• 2. Business rules may be added.e.g A rule that
  User has to login for adding to cart or for
  Checkout etc.
• 3. Some additional field may be required to
  differentiate completed and uncompleted orders.
  Or completed orders can be deleted from table
  itself as all the details will be stored in Order
  table once order is placed.

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Order Management Component

• Implemented Enterprise Component Pattern
•  
• Façade Interface IOrderManagement
• Façade Class OrderManagement
• Mediator OrderController
• FactoryFactory
• Work Flow ProcessOrderWorkFlow(Future place for
  GOOD rules)
• Other business interfaces and classes
• IOrder, AOrder, Order
• IOrderLineItem, AOrderLineItem, OrderLineItem
• IDiscount, ADiscount, Discount, DiscountRule
• Database façade classes
• IDBFacade, ADBFacade, DBFacade

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Order Management Component
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OM Dependent Components

• Shopping Cart Management Component.
• Customer Management Component
• The published services in the façade interface
• createOrder()
• chageBillingaddress()
• changeShippingaddress()
• changeShippingMethod()
• changePaymentMethod()
• acceptTerms()
• processOrder()
• SendConfirmation()
• viewOrderHistory()
• checkOrderStatus()
• showOrderDetails()
• generateInvoices()

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Order Management

• used services that provided by ShoppingCart
  Component
• public String getCustomerID()
•  
• addItem()
• getBillingAddress()
• getCartItems()
• getPaymentMethod()
• getShippingAddress()
• getShippingMethod()
•  
•  

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Order Management

• Implemented Model Control View (MVC) pattern
• JSP-Servlet-JavaBean architecture
• Used ConnectionPool for database connection
• Relational Database in MySQL.
• Tables in relational database.
• 1.      orderinfo
• 2.      items
• 3.      billingaddress
• 4.      shippingaddress
• 5.      shippingmethod
• 6.      paymentmethod

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Order Management

• The implemented flow in the component is shown in
  the figure below

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Order Management

• Completed Portions
• Create Order
• Generate Invoices
•  
• To be done
• Change Billing Address
• Change Shipping Address
• Change Shipping Method
• Change Payment Method
• View Order History
• View Order Status
• Accept Terms and Condition
• View Order Details.

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eBazaar

• Customer Management Component

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Customer Management Subsystem
Manages customers for the ebazaar, has following
functionality on a customer -View -Edit
-Delete -Add -Search
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Servlets

• Following Servlets (Controller) perform
  request/response and database connectivity
  management within the subsystem.
• NewUserSignupServlet
• SignInServlet
• UpdateServlet
• DeleteServlet

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JSPs

• Following JSPs provide users view of the
  subsystem
• NewUserSignIn
• SignOn
• Welcome
• Search
• Update
• ViewList

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The Customermanagement component

• It is an EJB component which consists
• CustomerHome- home interface
• CustomerBean- entity bean with CMP Fields
• Customer-remote interface
• CustomerController- EJB remote interface
• CustomerControllerBean- session bean
• CustomerControllerHome- home interface

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Classes and Interfaces

• Following classes and interfaces are part of
  component
• CustomerManagementSystem
• PaymentMethod
• Address, BillingAddress
• CardPayment
• PaymentMethod
• ShippingMethod

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Add New feature

• Using GOOD to add new features to an existing
  software application

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• lttrgtlt!-- Row 2 --gt
• lttd bgcolor"C0C0C0" align"center"gt
• ltform name"SaveCart" action"/ebz/ebazaarappl
  icationgateway"gt
• ltinput type"submit" value"Save Cart"gt
• ltinput typehidden name"eventToken"
  value"SaveCart"gt
• lt/formgtlt/tdgt
• lt/trgt

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• ltProduction name"VisitorOption-2" type"Choice"
  info"mandatory"gt
• ltNon_Terminal name"Search"/gt
• ltNon_Terminal name"Selection"/gt
• ltNon_Terminal name"SignOut"/gt
• ltNon_Terminal name"AddProduct"/gt
• ltNon_Terminal name"ShowCart"/gt
• ltNon_Terminal name"CheckOut"/gt
• ltNon_Terminal name"SaveCart"/gt
• lt/Productiongt

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• ltProduction name"SaveCart" type"Sequence"
  info"mandatory"gt
• ltEvent name"SaveCart" type"response"
  info"mandatory"/gt
• ltAction name"SaveCart" type"ui
  info"com.ebazaar.productmanagement."/gt
• ltNon_Terminal name"ShopperOption-1"/gt
• lt/Productiongt

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• package com.ebazaar.ebazaarcomponent.handlers
• import com.ebazaar.productManagement.
• import com.ebazaar.ebazaarcomponent.event.
• import com.ebazaar.common.utils.
• import com.ebazaar.shoppingcartmanagement.
• import com.ebazaar.customermanagement.ejb.
• import com.ebazaar.common.
• import javax.servlet.
• import javax.servlet.http.
•  

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• public class SaveCart extends DefaultBaseEventList
  ener
• public SaveCart()
•  
• public IBaseEvent doAction(DefaultEventEnv e)
  
•  
• System.out.println("Save Cart Action")
•  
• ResponseEvent responseEvent new
  ResponseEvent()
• responseEvent.setActionString("/sc/ebz
  _shoppingcart.jsp")
• // responseEvent.setActionString("/ec/main
  .jsp")
• responseEvent.setResponseType("ui")
• return responseEvent

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EBazaar

• Adding New Functionality
• MUM, 2001

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7 Steps to Do

• Select the right page (jsp file)
• Add UI control source (e.g. Button)
• Open XML File that stores the Grammar
• Find the correspond Production Rule and add Non
  Terminal
• Create Production Rule
• Write Event Handler (Java Class)
• Compile the class, Rebuild the Application

45
Case GoToMain

• Statement of Change
• A user may cancel or postpone the order when
  he/she is in the confirm order screen
• The screen should have a functionality to jump to
  the front page. This is a short cut for a user to
  log out and have some coffee break without
  worrying about his/her order

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Step 1 Select the right JSP file
ebz_shoppingcart.jsp
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Step 2 Add UI Control Source
ebz_shoppingcart.jsp cut here ... ltform
name"ShowCart" action"/ebz/ebazaarapplicationgat
eway"gt ltinput type"submit" value"Continue
Shopping"gt ltinput typehidden name"eventToken"
value"ContinueShopping"gt lt/formgt ltform
name"CheckOut" action"/ebz/ebazaarapplicationgat
eway"gt ltinput type"submit" value"Check
Out"gt ltinput typehidden name"eventToken"
value"CheckOut"gt lt/formgt ltform name"GoToMain"
action"/ebz/ebazaarapplicationgateway"gt ltinput
type"submit" value"Main"gt ltinput typehidden
name"eventToken" value"GoToMain"gt lt/formgt
cut here .
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Press Button Added
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Step 3 Open The Grammar

• File Account_management_2.xml

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Step 4 Add Non-Terminal
ltProduction name"ShopperOption-1" type"Choice"
info"optional"gt ltNon_Terminal
name"ContinueShopping"/gt ltNon_Terminal
name"CheckOut"/gt ltNon_Terminal
name"GoToMain"/gt lt/Productiongt
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Step 5 Create Production Rule
ltProduction name"GoToMain" type"Sequence"
info"optional"gt ltEvent
name"GoToMain" type"response"
info"mandatory"/gt ltAction
name"GoToMain" type"ui" info"com.ebazaar.sho
ppingmanagement."/gt ltNon_Terminal
name"OnlineShopping"/gt lt/Productiongt
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Step 6 Write Event Handler
package com.ebazaar.ebazaarcomponent.handlers im
port com.ebazaar.common. import
javax.servlet. import javax.servlet.http. impo
rt com.ebazaar.ebazaarcomponent.event. public
class GoToMain extends DefaultBaseEventListener
public GoToMain() public IBaseEvent
doAction(DefaultEventEnv e)
ResponseEvent responseEvent new
ResponseEvent() responseEvent.setAc
tionString("/ec/main.jsp")
responseEvent.setResponseType("ui")
return responseEvent
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Step 7 Recompile Rebuild
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J2EE and Application Server Techniques

• Deployment Concepts

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What is an EAR file?

• Enterprise Archive

Web .html and .jsp files java .class
Deployment descriptor
war
Deployment descriptor
ear
jar
Java .class file EJBs or java beans
Deployment descriptor
ltapplicationgt ltdisplay-namegtEBAZAAR (J2EE
application)lt/display-namegt ltdescriptiongtEBAZAA
R Components Integrationlt/descriptiongt
ltmodulegt ltejbgtpm-ejb.jarlt/ejbgt
lt/modulegt ltmodulegt ltejbgtcm-ejb.jarlt/ejbgt
lt/modulegt ltmodulegt ltwebgt
ltweb-urigtebazaar-web.warlt/web-urigt
ltcontext-rootgt/ebazaar-weblt/context-rootgt
lt/webgt lt/modulegt lt/applicationgt
Application.xml
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What is the E-bazaar EAR file?

• Enterprise Archive

Web .html and .jsp files java .class
Deployment descriptor
war
Deployment descriptor
ear
jar
Java .class file EJBs or java beans
Deployment descriptor
ltapplicationgt ltdisplay-namegtEBAZAAR (J2EE
application)lt/display-namegt ltdescriptiongtEBAZAA
R Components Integrationlt/descriptiongt
ltmodulegt ltejbgtpm-ejb.jarlt/ejbgt
lt/modulegt ltmodulegt ltejbgtcm-ejb.jarlt/ejbgt
lt/modulegt ltmodulegt ltwebgt
ltweb-urigtebazaar-web.warlt/web-urigt
ltcontext-rootgt/ebazaar-weblt/context-rootgt
lt/webgt lt/modulegt lt/applicationgt
Application.xml
Due to a limitation in Orion App server (Session
cannot be accessed across multiple beans), We
have to put all web application files in the same
war file. EJB files are specified explicitly
(not in a war file).
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ltweb-urigtebazaar-web.warlt/web-urigt

• The Web URI specifies a logical name for the web
  application
• This will be referenced in the default-web-site.xm
  l file so it can redirect requests to the
  physical location of the application (e-bazaar)
  files
• http// localhost8080/ebz/ec/main.jsp

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Server.xml

• Application name is set in server.xml
• Orion server assigns an application name to the
  path of the EAR application that will be used
  during access to the default-web-site
• Access to the app server is through the
  default-web-site.xml

ltapplication-server application-directory"../app
lications" deployment-directory"../application-d
eployments" gt ltrmi-config path"./rmi.xml"
/gt ltloggt ltfile path"../log/server.log"
/gt lt/loggt ltglobal-application name"default"
path"application.xml" /gt ltweb-site
path"./default-web-site.xml" /gt ltapplication
name"EBAZAAR" path"../applications/ebazaar.ear"/
gt lt/application-servergt
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Default-web-site.xml

• Assign the logical application name to a context
  and physical root directory
• A reference to this directory will execute the
  application
• We define the context-root app name for the
  default-web-site, here.
• Access to the default-web-site

ltweb-app application"EBAZAAR" name"ebazaar-web"
root"/ebz" /gt
ltweb-site host"ALL" port"8080"
display-name"Default Orion WebSite"gt lt!-- The
default web-app for this site, bound to the root
--gt ltdefault-web-app application"default"
name"defaultWebApp" /gt ltweb-app
application"EBAZAAR" name"ebazaar-web"
root"/ebz" /gt lt!-- Access Log, where requests
are logged to --gt ltaccess-log path"../log/defaul
t-web-access.log" /gt lt/web-sitegt
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user
/ebz
/default-web-app
Recognizes context
Recognizes appl name
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Default-web-site.xml
Define the root (logical) path /ebz This root
will refer to the specific application
name EBAZAAR This root need to know the
URI-Context to access the physical location
inside the EAR Ebazaar-web
Application.xml defines the URI-context Server.xml
defines application name Default-web-site
defines the root
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Setting the Datasource Name
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