Ch 3. Wireless Internet, Mobile IP and Wireless Web

1. Ch 3. Wireless Internet, Mobile IP and Wireless Web Myungchul Kim mckim@icu.ac.kr

2. Internet • IP Overview • Mobile IP • Basic Web • Semantic Web and XML

3. Wireless Browser Figure 2: Getting Information over web Content (XML/HTML) 4 http 2 Wireless Gateway Web Server Wireless Network 5 1 Back-end Systems and Darabases 3 http over wired Internet Web Browser Web Gateway 1. Access from Web browser to Web Server over wired Internet 2. Access Web contents from HTML/XML files 3. Access to non-Web content through a Wen gateway 4. Access from cellular phone over a wireless network 5. Access from wireless gateway to Web Server over wired Internet

4. Computer 1 Computer 2 Telnet Others Telnet FTP SMTP HTTP FTP SMTP HTTP Others TCP UDP TCP UDP IP IP Physical Network Physical Network

5. Partial View of Internet www.sun.com arts.um.edu 75.10.17.3 IP WAN3 108.2.11.7 IP WAN2 www.IBM.com Switch /Gateway 75.10.17.1 cs.um.edu Switch/Gateway 108.2.11.5 Switch/Gateway IP WAN1 (Typically ATM, Frame Relay, X.25) Bank1.co..uk 83.13.17.3 Level3.co..uk 83.13.17.4 • DNS (Domain Name Services) translates cs.um.edu to 108.2.11.5 • Telnet cs.um.edu = Telnet 108.2.11.5 • FTP cs.um.edu = FTP 108.2.11.5

6. Network Categories LAN LAN MAN WAN LAN LAN LAN MAN LAN * wide area network (WAN): common carrier, long distance, typically 56 kbps * local area networks (LAN): no common carrier, short distance, upto 100 mbps * metropolitan area networks (MAN): LAN of a city

7. Network Convergence to IP Applications (Data, Voice, Video) Internet Protocol (IP) Currently IPv4, Future IPv6 Network Technologies (Ethernet, Token Ring, Wireless, ATM, Frame Relay, X.25, FDDI, and many more)

8. NGN is IP-Based (“IP Dialtone”) Data Applications (typically Web based) Voice and Video Applications SIP (IETF) H.323 (ITU) Telnet FTP SMTP HTTP DNS Others UDP (User Datagram Protocol) TCP (Transmission Control Protocol) Other Transport Protocols IP (Internet Protocol) F-Ethernet FDDI X.25 ATM Frame Relay Other Physical Networks Sonet (150 Mbps to 100 Gbps)

9. Mobile IP • Enable computers to maintain Internet connectivity while moving from one Internet attachment point to another • Mobile – user's point of attachment changes dynamically and all connections are automatically maintained despite the change • Nomadic - user's Internet connection is terminated each time the user moves and a new connection is initiated when the user dials back in (traveler) • New, temporary IP address is assigned • How is this different from DHCP

10. Mainframe NSP and ISPs NSP POP POP IP Network ISP (POP + Web services) Dialup • POP(Point of Presence) provided by an NSP only provides a local phone access. The user can choose an ISP • An ISP provides an IP address (user dials in) • When the user moves, has to disconnect and redial again.

11. Operation of Mobile IP • Mobile IP goal is to allow users to seamlessly roam from private networks (e.g. Ethernet, wireless LANs) to public networks. • Mobile node is assigned to a particular network – home network • IP address on home network is static – home address • Mobile node can move to another network – foreign network • Mobile node registers with network node on foreign network – foreign agent • Mobile node gives care-of address to agent on home network – home agent

12. Mobile IP Scenario Mobile Node A NSP POP Home Network for A 3 Foreign Agent NSP POP Foreign Network for A 4 2 Home Agent IP Network 5 1 ISP Servers

13. Capabilities of Mobile IP • Discovery – mobile node uses discovery procedure to identify prospective home and foreign agents • Registration – mobile node uses an authenticated registration procedure to inform home agent of its care-of address • Tunneling – used to forward IP datagrams from a home address to a care-of address Discovery Tunneling Registration UDP ICMP IP

14. two ways to acquire a care-of address • the care-of address is an IP address of the foreign agent: it allows many mobile nodes to share the same care-of address. • A colocated care-of address is a care-of address acquired by the mobile node as a local IP address (through DHCP) • rough outline of the operation of the Mobile IP protocol • mobility agents advertise their presence via agent advertisement messages. A mobility node may optionally solicit an agent advertisement message by using an agent solicitation message.

15. 2. A mobile node receives an agent advertisement and determines whether it is on its home network or a foreign network. 3. When the mobile node detects that it is located on its home network, it operates without mobility services. If returning to its home network from being registered elsewhere, the mobile node deregisters with its home agent through a variation of the normal registration process. 4. When a mobile node detects that it has moved to a foreign network, it obtains a care-of address on the foreign network. 5. The mobile node, operating away from home, then registers its new care-of address with its home agent through the exchange of a registration request and registration reply message. 6. Datagrams sent to the mobile node’s home address are intercepted by its home agent to the mobile node’s care-of address, received at the tunnel endpoint and finally delivered to the mobile node. 7. In the reverse direction, datagrams sent by the mobile node may be delivered to their destination using standard IP routing mechanisms, without necessarily passing through the home agent.

16. Ongoing work and open questions • Routing inefficiencies • Triangle routing • Route optimization • Security issues • Firewalls • Such communications, originating from the mobile node, carry the mobile node’s home address, and would thus be blocked by the firewall. • Ingress filtering • User perceptions of reliability • Slow growth in the wireless LAN market • Current development efforts • Vertical handoffs between dissimilar media • Ad-hoc networking

17. Web and XML Basic Web HTML Web browsers Web servers HTTP Next Generation Web and XML XML and other markup languages Object-orienting the Web

18. World Wide Web • WWW is a collection of middleware that operates on top of the Internet. • WWW middleware supports the growing number of users and applications • Basic WWW middleware is based on a few simple concepts and technologies – Web servers – Web browsers – Uniform Resource Locator (URL) – Hypertext Transfer protocol (HTTP) – Hypertext Markup Language (HTML) – Gateways to non-Web resources

19. World Wide Web Overview EC/EB Applications World Wide Web Middleware (Web browsers, Web Servers, HTTP, HTML, Web Gateways) IP Network Stack …FTP, Telnet, SMTP, SNMP, NFS, and Others UDP (User Datagram Protocol) TCP (Transmission Control Protocol) Internet Protocol (IP) Physical Network USWeb Professional Certification Legacy Systems and the Web

20. Databases Example of Web UNIX Macintosh PC Web Browser (Hot JAVA) Web Browser (Netscape) Web Browser (Explorer) HTTP HTTP HTTP Web Search Tools Web Site cs.uc.edu o Web server (program) o HTML Documents o (Faculty.html, courses.html) Web Site www.books.com o Web server (program) o HTML Documents o Gateway for Database Access URL: http://cs.um.edu/faculty.html

21. Web Servers • Web servers provide the content for Web users. • Web servers are populated by the content providers. • Conceptually: a Web server is a catalog of information • In reality: a Web server is • Server software (e..g., Apache) • a collection of HTML files • Gateways to non-HTML resources (CGI, Servelet,,) • In many cases, a machine is dedicated/designated as a Web server . • Convention: content providers begin with designated "home pages" • Home pages include company logo, fancy artwork for attention, special deals, overviews, pointers to additional information, etc.

22. First Generation Web Architectures(HTML, HTTP, CGI) Web Browser Web Site HTML Docs HTTP Web Server HTML Displays CGI Corporate Databases and Applications

23. Semantic (Next Generation) Web • Many developments • Key idea: expanding the scope from human interactions to machine interactions • HTML to XML : exchange formats • HTTP to HTTP-NG: State handling • Improved programmability: • Access remote objects • Object view (Document Object Model) • Many others (detailed programmability, digital signatures) • Reference: www.w3.org

24. Next Generation Web Model - Key Players XML Semantic identification of fields Resource Description Framework (RDF) Metadata and Data Type Facilities Document Object Model (DOM) Behavior and Behavior Attachments Protocols and Messaging Web-IDL, HTTP-NG,

25. XML (eXtensible Markup Language) • Gaining importance for common data representation • “Simpler” than SGML (subset of SGML) • More “general” than HTML • Example: <CUSTOMER> <NAME> Joe </NAME> <ADDRESS> NY </ADDRESS> </CUSTOMER> • Great deal of activity in Ecommerce (competition to EDI), messaging middleware, data transformers, data management, publishing, etc.

26. XML Family XML DTD for Validation XSL for Presentation Variants WML (wireless) VML (voice) MathML ... XML (Extensible Markup Language) XML Query Language • Other features of XML • XML Link • XML Signature • XML Path (point to • specific sections of docs) XML Schema for Data Representation

27. Customer Record in XML <?xml version=“1.0” standalone=“yes”?> <customer> <name> <first>Amjad</first> <last>Umar</last> </name> <address> <street>MCC-1C337B</street> <street>445 South Street</street> <city>Morristown</city><state>NJ</state> <zip>07960</zip> </address> <phone>973-829-3114</phone> </customer>

28. XML Tree Customer Phone Address Name City State Zip Last Street First

29. Well-formed versus Valid • A Well-Formed Document: • adheres to the syntactic rules defined by the XML standard • E.g. Tags are delimited by < and > • A Valid Document: • A well-formed document that also adheres to the rules of a specified Document Type Definition (DTD) • DTD: • specifies a set of rules for the structure of the document Well-formed Valid DTD

30. A DTD for a Customer <!ELEMENT customer (name, address?, phone?)> <!ATTLIST customer id CDATA #REQUIRED> <!ELEMENT name (first, middle?, last)> <!ELEMENT address (street+, city, state, zip)> <!ELEMENT phone (#PCDATA)> <!ELEMENT first (#PCDATA)> <!ELEMENT middle (#PCDATA)> <!ELEMENT last (#PCDATA)> <!ELEMENT street (#PCDATA)> <!ELEMENT city (#PCDATA)> <!ELEMENT state (#PCDATA)> <!ELEMENT zip (#PCDATA)> … We can save this into a file called customer.dtd Note: PCDATA cannot have XML tags

31. Valid XML document <?xml version=“1.0” standalone=“no”?> <!DOCTYPE customer SYSTEM “customer.dtd”> <customer id=“12345”> <name> <first>Amjad</first> <last>Umar</last> </name> <address> <street>MCC-1C337B</street> <street>445 South Street</street> <city>Morristown</city><state>NJ</state> <zip>07960</zip> </address> <phone>973-829-3114</phone> </customer>

32. Well-formed but not Valid XML document <?xml version=“1.0” standalone=“no”?> <!DOCTYPE customer SYSTEM “customer.dtd”> <foo1 id=“12345”> <foo2> <foo3>Amjad</foo3> <foo4>Umar</foo4> </foo2> <foo5> <foo6>MCC-1C337B</foo6> <foo7>445 South Street</foo7> <foo8>Morristown</foo8><foo9>NJ</foo9> <foo10>07960</foo10> </foo5> <foo11>973-829-3114</foo1> </foo1>

33. XSL How to run example: c:\>xt customer.xml transform.xsl customer.html HTML XSL Processor XML Document XSL Stylesheet MS Word XSL Processor • <xsl> • <rule> • <target-element type=customer/> • <HTML> • <BODY> • <children/> • </BODY> • </HTML> • </rule> • </xsl> email XSL Processor XSL Stylesheet EDI XSL Processor

34. W3C Web Architecture Others P3P PICS SVG (scalable Vector Graphics) HTTP HTML SMIL DOM MathML Resource Description Framework (RDF) XML PICS: Platform for Internet Content Specification P3P: Platform for privacy preferences SMIL: Synchronous Multimedia Interaction Language DOM: Document Object Model

35. Concluding Comments • Internet and Web are foundation of Ecommerce • Basic components of Web (HTML, HTTP, Browsers, Servers) • Web is proceeding in several directions • We have discussed two: • Improving human access • XML • Web automation • Issue: will Web become too complex References: • www.w3.org • IEEE Internet Computing, January 1999