Building Wireless Internet Applications

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Building Wireless Internet Applications
Wireless Developer Workshop

• Module 3

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Architectural Map
Thin Client
Mobile Data Store
Device Identification
Data Synchronization
Content Transformation
iAnywhere Wireless Server
Messaging
Security
Enterprise Integration
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Topics

• Wireless Internet Characteristics
• Development Overview
• Developing Internet Applications
• J2EE Servlets and JSPs
• J2EE Wireless Framework
• Using XML/XSL

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Wireless Internet Characteristics

• Browser based applications
• No deployment required
• Dynamic content
• Multiple devices
• Many different browsers
• Many different markup languages
• Messaging
• Notifications and alerts
• Integrated business logic
• Logic remains on server platform

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Development Overview

• Browser Based applications/Multiple Devices
• JSPs, Servlets, XML/XSL
• Markup language (WML, HTML, etc)
• Messaging
• JMS
• Integrated Business Logic
• EJBs

Java
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Developing Internet Applications
PageServer
HTTP Server
Database Connectivity
HTTP
HTML
ComponentTransactionServer
Name Server
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The Good News

• When you buy an application server, it provides
  basic services for hosting components
• Connection pooling
• Transaction management
• Component life cycle
• Security
• Multi-threading
• Name services
• Dynamic page services
• Messaging

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The Bad News

• Each vendor provides these services as a set of
  proprietary APIs
• Pages not portable between servers
• Components not portable between servers
• Developer locked into a vendor

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The SolutionJava 2 Enterprise Edition (J2EE)

• Defines a standard for developing multitier
  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

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J2EE Architecture
JSPEngine
JDBC
JavaMail
HTTP Server
Servlet Container
JNDI Server
EJB Server
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What is a Servlet?

• Server side Java program that extends the
  functionality of a Web Server
• Used to dynamically generate markup language
  based documents
• Comparable to
• CGI
• Netscape NSAPI
• Microsoft ISAPI
• Apache Modules

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Servlets Benefits

• Written in pure Java
• Platform independent
• Can take advantage of JDBC, EJB, JMS, JavaMail,
  JavaIDL, RMI, ...
• Server independent
• Scalability
• Dont start new process for each request
• Can run in same server process as HTTP server
• Multi-threaded

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Building a ServletUsing the Servlet API

• Extend HttpServlet
• Code Servlet's life cycle Methods

Servlet
GenericServlet
HttpServlet
LogonServlet
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Java Server Pages

• Web scripting technology
• Creation of dynamic content using static
  templates
• Combine markup (WML, HTML, VoiceXML, XML, etc.)
  with Java Code to produce a dynamic web page
• Similar to ASP
• Uses Java as its scripting language
• Full power of the Java language
• Simple tags allow non Java developer to generate
  dynamic content

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A Simple JSP

• lthtmlgt
• ltbodygt
• lt_at_ page language"java" import"" gt
• ltH1gtWelcome back,
• lt
• String user (String) session.getAttribute("user
  ")
• out.println(user)
• gt
• lt/H1gt
• lt/bodygt
• lt/htmlgt

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How it Works
User Request
Server
FileChanged ?
Create Source
Compile
Execute Servlet
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Java Server Pages and Servlets

• Servlets
• Markup language enclosed in Java code
• JSP
• Java code enclosed in markup language
• Easier to author
• Better tool support

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J2EE Wireless Framework What it Offers

• Reduced development complexity
• Global data members
• Extends capabilities of Java Servlets/JSPs
• Device identification
• Parallel content with single URL
• Application management
• Session management
• User authentication
• Flow management

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J2EE Wireless Framework What it Offers

• Enterprise data integration
• JDBC/ODBC
• Custom adapters
• XML
• Messaging integration
• JMS access to Messaging systems
• Servlet, JSP and XML/XSL development

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J2EE Wireless Framework Device Identification

• Provides the ability to detect the device type
  and content type to format the data appropriately
• Redirector allows you to have parallel content
  with a single URL
• Stored information about devices can be accessed
  to generate appropriate content
• Language support
• Image support

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J2EE Wireless Framework Device Identification

• Specific browsers recognition built-in
• Nokia WML
• Ericsson WML
• UP.Browser
• Palm VII PQA
• MS Pocket IE
• NTT i-mode
• Neomar
• MS Internet Explorer
• Netscape
• Can develop generic recognition

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J2EE Wireless Framework Application Management

• Session management
• Most wireless devices cant use cookies so server
  needs to be able to manage session information
• Via server-side cookies or URL rewriting
• User doesnt have to be concerned with underlying
  implementation

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J2EE Wireless Framework Application Management

• User Management
• Authentication
• Personalization
• Flow Management
• Filters provide pre-built functionality
• i.e. LoginFilter

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J2EE Wireless Framework Messaging

• Java Message Service (JMS) provider for mobile
  messaging system
• Notifications, alerts
• Allows integration between thin-client and
  smart-client applications

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Thin Client Development Options

• Static content
• Dynamic content
• Java Servlets
• Java Server Pages
• XML content with XSL style-sheets

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Developing Internet Applications Static Web Site
HTTP Server
HTTP
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Dynamic Page GenerationUsing Servlets and JSP
JSPEngine
HTTP Server
JDBC
HTTP
Servlet Container
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J2EE Wireless Framework

• Simplifies the development of thin client
  applications
• Extends HTTPServlet with additional functionality
• ianywhere.framework.Application class allows you
  to develop web based apps the same way you would
  develop regular Java classes
• Global data members throughout application

public class MyApp extends ianywhere.framework.Ap
plication public void mymethod(Request req,
Response res)
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Building a ServletUsing the iAnywhere Framework

• Extend
• ianywhere.framework.Application
• Code servlet's business methods

Servlet
GenericServlet
HttpServlet
Application
Logon
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Thin Client Servlet Generated Content

• StringBuffer s new StringBuffer()
• s.append("lthtmlgt\n")
• s.append("ltheadgt\n")
• s.append("lttitlegtTitle on Pagelt/titlegt\n")
• //more code here for simple or complex logic
• out.print(s.toString())
• out.flush()

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Building the Application

• Step 1 Retrieve client information
• Step 2 Identify the content type
• Step 3 Identify the browser type
• Step 4 Create content appropriate for the
  mobile browser

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Step 1 Getting client information

• String reqType req.getUserAgent().getPreferredTy
  pe()
• resp.setContentType( reqType )
• HttpServletRequest hr req.getHttpRequest()
• String agent hr.getHeader( "user-agent" )
• String device agent.getDevice()
• String deviceID agent.getDeviceID()

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Step 2 Identifying Content Type

• if ( reqType.equals( MIMEType.WML ) )
• //Generic WML content
• else if (reqType.equals( MIMEType.HTML))
• //Generic HTML Content

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Step 3,4 Identifying Device Broswer

• if ( agent.equals( NokiaUserAgent" )
• //nokia specific content here

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XML Document Characteristics

• No presentation information
• No specification of type style or color
• No specification of format table, list, bold,
  etc
• Tags are application-oriented
• ltproductgt, ltquantitygt, etc, instead of just ltpgt
• Easy to distinguish Bandages as Product vs
  Price

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Presentation Using XSL

• XML documents omit all formatting
• Formatting is supplied by XSL
• XSL Extensible Style Language
• Specified separate from the XML document
• Allows multiple XSL specs for one XML document
• An XSL spec maps
• An XML document type to HTML, or
• One XML document type to another

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J2EE Wireless FrameworkXML Server

• Permits XML access to relational databases
• Data retrieval, inserts, deletes and updates
• Allows for one content source for multiple client
  types using XSL
• Takes advantage of connection caching mechanism
  in iAnywhere Wireless Server

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XML transformation
XSL Stylesheet
XSL Stylesheet
XML Document
XSL Stylesheet
XSL Stylesheet
XSL Stylesheet
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Building the Application

• Step 1 Create an instance of XML Server
• Step 2 Specify the XSL style sheet
• Step 3 Specify database properties and
  execute the query
• Step 4 Transform resulting XML document and
  output the results

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Step 1 XSL Style Sheet
XMLServer xml_server new XMLServer() xml_server
.create()
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Step 2 XML Server

• xsl baseURI "xsl/wml/OrderListMaster.xsl"
• xml_server.setXsl(xsl)

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Step 3 Database Access

• xml_server.setUserid("dba")
• xml_server.setPassword("sql")
• xml_server.setSQL("SELECT order_id, product_name,
  orders.quantity, discount, orders.order_date FROM
  orders, product WHERE orders.product_id
  product.product_id AND status 'Pending' AND
  orders.rep_id " rep_id )
• xml_server.processSQLRequest()

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Step 4 Content Translation

• Document rs_xml_orders xml_server.getXMLDocument
  ()
• ByteArrayOutputStream byteOutStream new
  ByteArrayOutputStream()
• domImpl.writeDocument(rs_xml_orders,byteOutStream)
  
• out resp.getOutputStream()
• xsltImpl.transform( in,new InputSource( xsl ),out
  )

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Using PowerJ for Thin Client apps

• Complete J2EE support
• Tight integration with iAnywhere Wireless Server
• Automatic deployment of WebApplications
• Servlets
• JSPs
• Automatic deployment of EJBs
• Design-time syntax checking of JSPs
• Servlet Wizard can be used to develop
  applications based on the iAnywhere Wireless
  Server framework

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Summary

• Similar architecture to Internet applications
• more device and browser types
• New markup languages (WML, HDML, VoiceXML, etc)
• iAnywhere Solutions provides a server platform
  that simplifies wireless web development
• Multiple development options including Java
  servlets, JSPs and XML/XSL

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Building Wireless Internet Applications
Wireless Developer Workshop

• Module 3