1. Internet, intranet, and multimedia database processing l Database processing across local and wide area networks l Alternative architectures for distributing application logic to network clients

2. Databases and networks l Synergy between database and network (Internet, intranets) technologies l Examples? »Distance learning »Online testing »Electronic commerce »Planning (e.g., travel agents) »Banking »Voting, polling »…?

3. Terminology l Network: collection of computers communicating via a standard protocol »Public (Internet) »Private (intranets) l Internet: network of public networks (started by military to avoid single point of failure – ARPANET, 1960’s) l TCP/IP: Transmission Control Protocol / Internet Protocol

4. Internet applications/services l Email (messages) l FTP (file transfer) l Telnet (remote terminals) l Usenet (newsgroups) l IRC (chat) l WAIS (wide area information service) l HTTP (hypertext transfer) l...

5. World Wide Web l All of the Internet services, with a standard hypertext interface accessible via client browsers from servers (HTTP) »HTML: Hypertext Markup Language »SGML: Standard Generalized Markup Language l Started to organize and exchange Physics data at CERN (Tim Berners- Lee, 1989)

6. More on the Web l HTML: text, tags, and anchors » TWI Welcome to Time-Wasting, Inc. l URL: Uniform Resource Locator »protocol://servername[:port]/filepath l MIME: Multipurpose Internet Mail code »MIME TypeNameFile Extension text/htmlHypertext.htm, html text/plainText.txt image/gif Graphics I.F..gif...

7. Databases and the Internet l Can extend MIME types with application-specific files »Pro or con? Why? l Request oriented protocols »Pro or con? Why? l Stateless transactions »Pro or con? Why? True or false? l Insecure transactions »Pro or con? Why? True or false?

8. Intranets l Private LAN or WAN l Security »Disconnected from Internet »Firewall »Controlled data access, authentication... l Speed »100Mbs (versus 28.8kbs) »Multimedia applications become feasible

9. Network database applications l Users execute applications on the client via a browser l The database resides on the server, together with the web server l The DBMS can reside at either end (file- sharing versus client-server)

10. Database publishing l Static report publishing: the report is created off-line, saved in HTML format, and posted on the Web l Query publishing: the client uses a form to issue a query as part of an HTTP request, the server creates the report in HTML format and sends it back as a response to the client l Application publishing: application code transfers to the client and executes locally

11. DB query publishing example Form ASP Request

12. Network database applications l The continuum between thin and thick clients

13. Thin clients [Client] form.html sends: »“execute cgi_spam.pl with argument address ” [Server] cgi_spam.pl responds: »“ Ack You are done for. ” SPAM site Your email please:

14. Java database applications l Java is an OOPL (developed by Sun) l Java is compiled into machine- independent (portable) “bytecode” l Java bytecode is loaded from server to client, where it is interpreted and executed as a normal program l Java code can access the database via an ODBC interface or DBMS library

15. Java database applications: thin and thick clients

16. Microsoft Active Platform l Microsoft’s open architecture to deliver applications over the network l Various tools, services, and technologies »HTML and extensions »Scripting (JScript, VBScript, etc.) »Components (Java, ActiveX) l ActiveX controls »Based on OLE, COM, DCOM (Distributed Component Object Model) »Binary-level dynamic interface for Windows application (IUnknown, Query Interface) »Can be embedded into HTX documents

17. Support for network applications l Hyperlink (URL, UNC) data types l Application publishing (Java, ActiveX) l Tables, queries, and forms publishing »Static HTML (reports, too) »Dynamic HTML via ActiveX or 3rd-party ODBC “application servers” interacting with Microsoft internet servers –Need IDC and HTX or ASP files on server –What’s an example of an application server?

18. Multimedia database applications l Not necessarily related to networks l Can embed multimedia objects as links in databases: »Images »Sounds »Video l Large binary files: network bandwidth becomes a central issue

19. The future l Impact of databases on networks »Speed »Security »Electronic payment schemes »Agents to deal with dynamic pages (XML) l Impact of networks on databases »Huge new markets »New impetus for database research »Standardize interfaces »Simplify development