Basic Information Systems: Web, Database, and Distributed Objects

1. Topic I: X-InformaticsI-400 and I-590 Spring Semester 2002 MW 6:00 pm – 7:15 pm Indiana Time Geoffrey Fox and Bryan Carpenter PTLIU Laboratory for Community Grids Informatics, (Computer Science , Physics) Indiana University Bloomington IN 47404 gcf@indiana.edu uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

2. Topic I: Basic Information Systems • Basic Electronic Information Systems • Web Pages • Database • Sketch of Today's Internet including initial architecture • XML • Distributed Objects • Messages • Multi-Tiers • These features will emerge in greater depth as we go to further topics • Motivating Applications • Consumer to Business to Science • e-Science uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

3. Multi-Tier Client Server/Service for Data Access “Flat” FileSystem Relational Database Object Store Middle Tier Servers(Abstract Services) Back-end Tier Raw Services Client Tier Object Broker IIOP HTTP Web Server RMI Specialized Java Server Web Service SOAP + WSDL Old and New Useful Backend Systems uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

4. InformaticsView ofArchitecture Raw Data Resource • Note Server Tier uses lots of subsystems that are themselves separated by XML Interfaces XML for Data (Virtual) XML Interface Processing Server Information/Knowledge (Virtual) XML Interface XML for Knowledge Rendering to XML syntaxDisplay Format XHTML and SVG are examples Clients uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

5. Typical (non Microsoft) Architecture • This is .opennet structure Persistent Managed resource. Also could be sensor, supercomputer etc. Database (Virtual) XML Layer Resource Object layer Virtual Machine onServer Enterprise Javabeans Java Control User (Portal) Object layer (Virtual) XML Layer Form Output Page viewed by user Servlet uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

6. Basic Electronic Information Systems • Web Pages : Universal presentation mechanism as long as we view as “display” and NOT a file in backend • We have a universal display engine – the browser – which interprets HTML, SVG, XHTML • There is some uncertainty as where conversion from “knowledge” to “form suitable for browser” takes place • Lets call place conversion takes place – the display adaptor – this • Drives PC or PDA or cell phone • Incorporates user profile data • Display Adaptor is in “server tier” uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

7. Display Adaptor • User Profile is sort of permanent and is extracted from back end database (Virtual) Knowledge XML Interface User Profile(XML) Display Adaptor Rendering to XML syntaxDisplay Format Information (XML)about displaydevice, connectingnetwork etc. Broswer uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

8. Palm Tops help define Client Model • There is growing interest in wireless portable displays in the confluence of cell phone and personal digital assistant markets • By 2005, 60 million internet ready cell phones sold each year • 65% of all Broadband Internet accesses via non desktop applicances • One needs to design web systems so they can be accessed from either a PDA or a PC or a Powerwall • This implies that only code in browser should be that immediately needed to relay events between user and web system – all “logic” (state) should be outside browser. uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

9. Database I • This is a place where back-end raw data stored • It must have key characteristics • Can store data persistently i.e. if you write it database, you can be certain it will still be there a year from now • You can efficiently access information so that you get what you want accurately and quickly • Now this field IMHO is quite screwed up • “Databases” can be • (object) relational databases like Oracle or mySQL • One or more (XML) files on a disk uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

10. Database II • Efficient access needs to address fact that information can be stored in multiple places (split between disks) and that one stores in a hierarchical way on devices that get bigger and bigger • Larger device almost always are slower and give back data in large chunks • So need caching (replicating often used data) • Cunning positioning of data etc. • Finding out what data exists and where it is stored suffers from a historical problem …. uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

11. Database III • Most important is persistency – data is preserved • This requires well proven technology which CIO’s have confidence in • This implies use techniques designed in the past when client—server model was dominant and there were only a simple data structure • Label files with file names • Set up a bunch of tables in a relational database • So data structures are inadequate to represent object structure and as client server, we do not distinguish “knowledge view” from “raw data view” • Note databases are “just” file systems with a clever way of indexing into file gotten by pre-processing information uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

12. Database IV Relational Database Object Database Web Service • Ignoring display level, we compare old (top) and preferred (bottom) model • As need to support both models, we fiddle around with top model to make it support bottom • SQL used as access language uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

13. Basic Information Systems I • Today’s Internet is a mix of everything with the two major initiatives • .net from Microsoft • The Java-XML .opennet solution from IBM Oracle Sun • File systems (for web pages) and databases are storage mechanisms • Everybody agrees (correctly or incorrectly) that XML will describe information whether in raw or processed form • Objects – specified in XML – can be realized in any way that can be electronically accessed • Web pages are objects • Word on your PC is an object • A Java XML parser on server is an object • Objects are by definition distributed as the computers (network attached devices) they are on are distributed uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

14. Messages I • All Nature’s information systems are built on messages • Societies are collections of entities communicating via messages • people send messages called audio, phone, TV signals, books, web access • Bees and ants communicate via chemical messages • Components of a chip communicate via messages • Guns communicate with targets with messages called bullets • Neurons in your Brain communicate via messages along axons and dendrites • Protons and electrons communicate via messages which bind atoms together to create matter – messages are quanta of electromagnetic force uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

15. Messages II • Messages require communication channels and some sort of interfaces at start and end • Performance of a system often dependent on structure of communication system • Indiana has good networking • Consider cities – their functionality often depends on road system which needs to be designed to make messages (contents of cars and trucks travel well) • Tallahassee (Florida) has a bad architecture: Hub and Spoke • Most cities have a 2D Grid and a ring road uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

16. Messages III • Interesting “theory of complex systems” studies structure of “set of entities linked together” • Natures is very heterogeneous – several different messaging systems optimized over different criteria • “Field of Computer Architectures” studies among other things communication between parts – CPU Memory etc. Bad Good uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

17. Messages IV • Messages are • One-way (Receive or send(notify)) • Two-way (Solicit-response or Request-response) • Transactions (some certified change of state) • Messages are • Real time like speaking (synchronous) • Queued or batched like books (asynchronous) • All messages are like US Postal service • There is a “body” which delivery system doesn’t see • There is a header with data (address, what to do if problem, whether to request signature) used by routing/delivery system uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

18. Multi Tiers • Key to modern architecture is a set of interlocking “Web Services” – this gives a multi-tiered architecture but this isn’t a very good name • Better to think as “bunch of peers” communicating via messages • Raw data • Client Display • Horde of processing peers routing and converting information uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

19. Web/Grid Service Model • We used to think of a computer application as a bunch of processes running on a single computer • Now process is replaced by services and these run in a middleware “sea” with each service on separate machines (in general) and these machines spread around the “enterprise” (world) • Computer science is producing infrastructure – essentially the Web Operating System – to support this • ALL current software is “out of date” and must be rewritten – this includes software for a single PC uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

20. Web Services v. Client Server I Database Database Web Service • Web Services are “entities” with electronic message input and message output • There are special cases of web services where one end is either a “raw resource” or a “client” Original Client Server model can be re-interpreted as a “Service” where database hosted on a (Web) Server and Client Interface is a browser Raw resource uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

21. Web Services v. Client Server II Database Web Service • Client Server model: There is a way (SQL) of finding out what is in a database • User code uses SQL (or trivial variant of it) to extract information • So we always had a service model • Web Service (for client server) allows user to use Web browser as vehicle for making query • 3 tier version of above • User present a “knowledge query” in some fancy syntax • Web service (for 3 tier) converts “knowledge query” into “database syntax” (SQL) and similarly reformats response from database and returns to user uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

22. Web Services v. Client Server III Web Service Object Database Web Service Web Service Web Service • Clients have user interface input and output • Raw Resources have some sort non electronic source or are some disk or tape with a electronic output • Modern Web services can be chained together as well as • Allowing Web browser user interface • Converting being user and resource view of information uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

23. Software has variables and methods • Electronic Information Systems have • Properties • Basketball has raw events “Larry Bird sunk a 3-point shot on such a such date in game between X and Y” • Functions which take properties and results of other functions and convert them into higher level knowledge • Larry Bird’s lifetime scoring total is a function that sums shot events where he is shooter • Score in Game is sum of shooting events and other scoring events • Obviously you want to ONLY record lowest level properties and use functions where possible • All information has one and only one true persistent store – replicate for performance (CNN and ESPN might both have raw basketball events) • Fetching Property values and executing functions are both Web Services • Property values and output of functions are all XML specified objects • Events (“atomic information”) can be thought of as messages uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"

24. Homework Cases • Basketball • Electronic Shoebox • Education • Good discussions with students often discussing different facets • Basketball is statistics, teams, cards … • Shoebox is photos and memorabilia that creates family ties • Note statistics are functions • Note integration of information (web services) from different fields • Basketball team needs personal and geographical information • This implies that building information system is non trivial as need to “wait for” / “respect” work of other communities • E.g. IMS has defined “people information” for education but PeopleSoft, Microsoft (passport), Sun (Liberty Alliance), US Government (SSN) are “bigger” uri="gxos://ptliu/communitygrid/courses/xinformatics" title="Topic I"