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On Views and XML

On Views and XML. Serge Abiteboul INRIA PODS 1999. Organization. Introduction XML View := Query +:= Change Control +:= Objects +:= Structured & Semistructured Data +:= Active Features +:= Incomplete Information +:= more. Many Facets!. Warning.

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On Views and XML

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  1. On Views and XML Serge Abiteboul INRIA PODS 1999

  2. Organization • Introduction • XML View := Query +:= Change Control +:= Objects +:= Structured & Semistructured Data +:= Active Features +:= Incomplete Information +:= more... Many Facets! Views and XML - Serge Abiteboul

  3. Warning • This is not a survey on database views • This is not a tutorial on XML • This is about the use of XML&ecommerce as excuses to survey some works on views cast in a fashionable context: O2views, views of OEM, ActiveViews, Lorel/Ozone... (and also motivate future works) Views and XML - Serge Abiteboul

  4. Executive Summary: Database folks should be interested in XML Views and more and more are Footnote: this is a great way to recycle your old results on views, incomplete information, deductive databases, universal instance assumption, dependency theory, etc.

  5. Introduction: XML in short • Document mark-up language; descendant of SGML • Standard for data exchange on the Web • We are interested here in data exchange and not in document editing and retrieval Views and XML - Serge Abiteboul

  6. EXAMPLE: EDI Electronic Data Interchange • Standard for business data exchange • 2 standards: • ANSI X12 in US -- all B2G by end 1999 • EDIFACT in world -- UN committee • translate  EDI  transmit Views and XML - Serge Abiteboul

  7. <!DOCTYPE Book-Order PUBLIC "-//Editor//DTD Book Order Message//EN"> <Book-Order Supplier="4012345000094" Send-to="http://www.bic.org/order.in"> <title>Editor Lite-EDI Book Ordering</title> <Order-No>967634</Order-No> <Message-Date>19961002</Message-Date> <Buyer-EAN>5412345000176</Buyer-EAN> <Order-Line Reference-No="0528837"> <ISBN>0316907235</ISBN> <Author-Title>Labaln, Brian/Chrome</Author-Title> <Quantity>2</Quantity> </Order-Line> <Order-Line Reference-No="0528838"> <ISBN>0856674427</ISBN> <Author-Title>Parry, Linda (ed)/William Morris</Author-Title> <Quantity>1</Quantity> </Order-Line><input type="checkbox" name="partial" value="allowed"/> <text>Tick here if a delayed/partial supply of order is acceptable</text> <input type="checkbox" name="confirmation" value="requested"/> <text>Tick here if Confirmation of Acceptance of Order is to be returned by e-mail</text> <input type="checkbox" name="DeliveryNote" value="required"/> <text>Tick here if e-mail Delivery Note is required to confirm details of delivery</text> <E-Address>E-mail address: <input name="e-address" size="25"></input></E-Address> <Language>Please respond in:<select name="response-language"> <option value="EN" selected>English</option><option value="FR">Fran&ccedil;ais</option> <option value="DE">Deutsch</option> <option value="ES">Espagnol</option> <option value="IT">Italian</option> </select></language> <input type="submit" value="Press here to send completed form to supplier"> </Book-Order> data in XML/EDI Views and XML - Serge Abiteboul

  8. I personally prefer: Views and XML - Serge Abiteboul

  9. XML • Some noise and confusion • Is the syntax important? No • What is XML? • the means to exchange tree/graph data on the Web • an object-oriented API for it • more Views and XML - Serge Abiteboul

  10. A (simplified) model for XML XML-tree :- list(node) node :- string | element | ref node element :- label list(att : string) list(node) • label :- string • att :- string • an attribute occurs at most once Views and XML - Serge Abiteboul

  11. XML in short <person> <name>Serge Abiteboul</name>PODS invited speaker <a xml:link=`simple’ href=“gif/serge.gif”> old picture</a> <address> <city>Le Chesnay</city><zip>92310</zip></address> <a xml:link=`simple’ href=“www-rocq.inria.fr/~abitebou”>Web</a> </person> DTD: grammar DCD: some typing DOM: object API RDF: meta data XPOINTER/XLINK ... Views and XML - Serge Abiteboul

  12. XML Views Query Publish&subscribe Crawler&filter engine Security manager Request broker Business intelligence Output/report/delivery Data Warehouse Web browsers OLAP Web browsers View server Image video Web browsers reports Information repository Views and XML - Serge Abiteboul

  13. What databases can bring to XML is query optimization and query rewriting View := Query

  14. View = Query • like for relational model • use of query optimization techniques • use of query rewriting techniques • processing queries using views • main issue: virtual vs. materialized Views and XML - Serge Abiteboul

  15. B2C: Comparative Shopping http://www.addall.com • 24 bookstores searched in about 10 seconds • between $42 and $78 • that’s why people will use them! Views and XML - Serge Abiteboul

  16. What DB can bring to XML is the control of changes View +:= Change Control

  17. Some of the most studied problems for relational views update propagation: • incremental updates • view update problem Views and XML - Serge Abiteboul

  18. D2V: Incremental Updates • a customer has loaded portions of the catalog • some prices change • no need to reload the entire catalog • many such examples on the Web •  updates Views and XML - Serge Abiteboul

  19. V2D: View Update • Sometimes considered less of an issue: the Web is read only! • Many Web applications involve updates • We may be able to annotate the products of the catalog • some of the data is in read mode • some data is not visible (this is only a view!) • some data may be updated Views and XML - Serge Abiteboul

  20. Example: Change Detection A customer (self) is in a department (self.department) and may want to see only the current promotions of products in this department (MyPromotions) let MyPromotions be select I.* from I inCatalog.promotions.item where I.department = self.department Views and XML - Serge Abiteboul

  21. 99/02/01 description 01/05/03 super sale Query Subscription: Changes [from Chawathe’s thesis] Changes in label graphs : as in DOEM Catalog name Gismos78 item promotion department electronic price £234 self department £278 Views and XML - Serge Abiteboul

  22. Query Subscription: Changes • Change value of atomic vertex value • Creation of new vertex • Addition/removal of an edge • Change of the label on an edge: add/remove • Move a vertex: add/remove • annotations on edges and vertexes Views and XML - Serge Abiteboul

  23. Query Subscription: Queries select P.code, P.description from P in Catalog.product where P.price <changed>Q vertex annotation where P.<added>description edge annotation where P.price data in annotation <changed <old=Q’, date T>>Q and Q - Q’ > 100 and T > “99/04/03” Views and XML - Serge Abiteboul

  24. Query Subscription: Examples • On the first of each month, send me the list of all products in my interest list such that their price increased by more than 10% • Each time there are ten new employees, send me their names and departments • Notify me if the price of this house decreases • similarity on event when condition do action Views and XML - Serge Abiteboul

  25. XML +:= World of Objects The underlying model for XML is object-based and XML views should be based on OO(DB) technology

  26. Views +:= World of objects • API for XML: Domain Object Model • Views XML as object-oriented • Allows designing C++ or Java applications • E.g.: • use subclass Promotion of XMLNode • Catalog.promotionsis only a set of virtual elements • the list of promotions is generated on demand based on the nature of customers Views and XML - Serge Abiteboul

  27. Views in OODB: O2Views • Virtual values • like for relational views • entirely virtual XML document, e.g., view of relational data • virtual attributes e.g., product: code, name, price,… alternatives = the set of products that are “similar” and are on promotion Views and XML - Serge Abiteboul

  28. Views in OODB: O2Views • Virtual class: a set of database objects that are grouped together and as such acquire a new interface • catalog1/DTD1,…,catalog17/DTD17 • products are represented differently in each catalog • unique DTD that allows to view all products • each product can be “viewed” with that DTD Views and XML - Serge Abiteboul

  29. Views in OODB: O2Views • Imaginary class: groups objects that are all virtual, e.g., join of two relations • For more: see Souza’s thesis Views and XML - Serge Abiteboul

  30. XML data/views +:= semistructured + structured data XML should also allow the exchange of structured data as in relational/ODMG models

  31. Semistructured + Structured Data • If we know about the structure of data, not using it may damage performance • The use of structure facilitates the programming of applications, e.g., in Java • Structure may be useful to explain data to users • For more: see Lahiri’s thesis [and Ozone = OQL + Lorel ] Views and XML - Serge Abiteboul

  32. Web catalog - continued Product-basic all products category=electronic, subcategory=sound, name=Gismo223, code=F2GHYYRF, selling-price=1200FF Product-specific for Gismos only voltage=list(110,220), Gismo-norm=GHTF333 External resources description=http://m.ec.fr/cat/Gismo reviews=http://reviews.com/Gismo Private data buying-price=100$, quantity-in-stock=20000, supplier=Sears, authorized-discount=30% Regular data Semistructured data External data Other regular data Views and XML - Serge Abiteboul

  33. This data in XML <product> <basic> <cat> electronic <subcat >sound </subcat><cat> <n>Gismo223 </n><c>F2GHYYRF</c> <sp currency=French-franc>1200</sp> </basic> <specific> <v>110</v><v>220</v> <Gismo-norm>=GHTF333</Gismo-norm></specific> <external> … </external> <private> <bp currency=dollar>100</bp> <qis>20000</qis>, <s>Sears</s> <ad>30</ad></private><\product> Views and XML - Serge Abiteboul

  34. What is such data exactly? • A mix of structured and semistructured data with pointers between two worlds • Purely XML. Then • use a relation as a materialized view Product(name, code, category, subcategory, price, rest) • Index on name and subcategory select P.name, P.price from P in Product where P.subcategory = “sound” Views and XML - Serge Abiteboul

  35. Digression: storage of XML • as blobs • generic mapping : ignore the structure • specific mapping • relational • object • hybrid Views and XML - Serge Abiteboul

  36. As blobs <product><basic> <cat> electronic <subcat >sound </subcat><cat> <n>Gismo22</n><c>F2GHYYRF</c> <sp currency=French-franc>1200</sp> </basic><specific><v>110</v><v>220</v> <Gismo-norm>=GHTF333</Gismo-norm></specific> <external> … </external> <private><bp currency=dollar>100</bp> <qis>20000</qis>, <s>Sears</s> <ad>30</ad></private><\product> + full-text index Views and XML - Serge Abiteboul

  37. Generic mapping root product o1 o3 electronic o1 basic o2 o4 sound o2 cat o3 o5 Gismo223 o2 subcat o4 o6 F2GHYYRF o2 n o5 o7 1200... o2 c o6 o2 sp o7... o7 currency French-franc o12 currency dollar... element graph atomic objects attributes Views and XML - Serge Abiteboul

  38. Specific Class Product type tuple( cat:string; subcat:set(string); n: string, c:string; price: Price; specific: OEM; external: list(tuple(label:string;val:URL)); private pr: tuple( bp:Price; qis: integer; supplier: Company; ) ) type Price : tuple(sum:int, currency:Currency); Views and XML - Serge Abiteboul

  39. What is better? Hybrid? • Need for comparative studies • My feeling/common sense?: • Use structure for very structured portions of data • Use semistructured for less so or portions with very evolving structures • Use blobs for components accessed mostly via full-text indexing, e.g., paragraphs in a document Views and XML - Serge Abiteboul

  40. Views += Active Features

  41. Active Views • System developed at INRIA • Long term goals: • Declarative specification of data intensive applications with cooperation between partners • Ease of use and fast deployment • (Automatic) verification Views and XML - Serge Abiteboul

  42. Architecture JAVA DOM AVApi O2 Java application O2 Notification Java RMI XML repository ACTIVEVIEWS MANAGER Web Browser Java Client Views and XML - Serge Abiteboul

  43. Motivations • Database Applications: • passive behavior • closed systems • persistence, concurrency, access control • New needs • interactions between clients: e.g., notification • change control • reactive behavior • E.g: e-Commerce, cooperative work Views and XML - Serge Abiteboul

  44. Illustration of Interactions: Notification In the vendor view: when Customer.entersDept(dept) if dept = self.dept thennotifyme Views and XML - Serge Abiteboul

  45. Notification AVServer entersDept book AVClient customer notify notify AVServer AVClient vendor in book dept Views and XML - Serge Abiteboul

  46. Illustration of Interaction : Change Control In the customer view let monitoredMyPromotions be s elect I.name, I.price from I in Catalog.promotions.item where I.department = self.department read, write, append, monitored, refresh, deferred… simpler case: monitoring of the catalog Views and XML - Serge Abiteboul

  47. Change control 3 Modification AVServer 4 Write 1 Read AVClient 6 Notification 2 Read 7.Read 5 Notification AVServer AVClient Views and XML - Serge Abiteboul

  48. Choices • All XML • XML repository • XML query language • XML views • Declarative specification • almost no code to write • compilation to an executable application • active rules Views and XML - Serge Abiteboul

  49. Important Aspects • workflow e.g., customization: to search for a biblio ref, look first in my own files, otherwise look in dblp otherwise look… • activities (search, buy, accounting, chat…) • active rules • logical traces • notifications Views and XML - Serge Abiteboul

  50. View +:= Incomplete Information Use something like Imielinski-Lipski tables

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