1 Specification of Web applications with ADM-2 Paolo Atzeni, Alessio Parente Università Roma Tre Thanks to P. Merialdo, M. Magnante, G. Mecca, M. Pecorone

2 An invitation... VLDB 2001: 27th International Conference on Very Large Databases Roma, September 2001 Register now! Very-early rate still available!

3 Outline Models in Araneus The Araneus methodology Homer, a CASE tool for “read-only” sites ADM-2: new features for applications A new methodology (by example)

4 Model-Based Development in Araneus Clear Separation between Site Design and Site Implementation: –high-level models for site design –tools for site implementation Overall Goal: –users should concentrate on design issues –they should not write any line of code: Homer, a case tool Flexibility in Site Implementation: –Transparent Generation of XML/XSL or HTML sites –Independence from the actual page-generation tool: programs for static or dynamic (JSP) pages.

5 Models in Araneus data design –ER –relational (or object-relational) hypertext design –"Navigational" ER (or NCM) –ADM Page Types presentation design –Telemachus Styles

6 A Web page

7 A page-scheme ProfessorPage Name Position Address ResearchList Area ToResP

8 ADM (Araneus Data Model): a logical model for Web hypertexts page-schemes “unique” pages simple attributes –text, images,... –link (anchor, URL) complex attributes: lists (possibly nested) heterogeneous union form (as virtual list over form fields and link to the result)

9 A Web page, with a list of links:

10 ProfessorListPage ProfessorList Name ToProfP A Web page, with a list of links: a “unique page”

11 ProfessorListPage ProfessorList Name ToProfP ProfessorPage Name Position Address ResearchList Area ToResP An ADM Scheme

12 Heterogeneous Union and Forms

13 ProfessorListPage ProfessorList Name ToProfP ProfessorPage Name Position Address ResearchList Area ToResP Name Submit U SearchProfPage Heterogeneous Union and Forms

14 Another ADM scheme (another representation)

15 Data Models ER ADM Database Conceptual Scheme (entities - relationships) Hypertext Logical Scheme (page-schemes, links) Not so close!

16

17

18 Navigational ER

19 From Navigational ER to ADM

20 Presentation Modeling: Telemachus Requirements: –precise notion of style for pages –platform independence –rapid prototyping and flexible maintenance –working with “sample” pages (“templates”). Telemachus Styles: –Attribute Styles: formatting directives for attributes in pages –Page Styles: collections of attribute styles plus header and footer.

21 Table: Courses CourseName... Operating Systems... In the hypertext: Course: TEXT;... CoursePage In the page: Course:[ ] [ ] Operating Systems Presentation Modeling: Telemachus Attribute Styles: –In the database:

22 The Araneus methodology ER NCM RDB ADM Styles Site

23 Homer: A Case Tool for Web Sites Different models and different activities: –database design ER relational (or object-relational) –site design "Navigational" ER ADM Page Types –presentation design Telemachus Styles A thorough design methodology Graphical interface to assist users in the design Automatic production of (Java) code for page generation.

24 Step 1 : Content Modeling (ER Scheme) DB Scheme Step 2: Site Structure Modeling (ADM Scheme) Step 3: Presentation Modeling (Page Templates) Site Generation Code Homer user editing Homer: Web Site Development Process

25 Step 1: Content Modeling User Draws an Entity-Relationship Scheme

26 Step 2: Site Modeling User Specifies Navigational Features

27 Step 2: Site Modeling Homer Generates the Site Scheme

28 Step 3: Presentation Modeling Homer Generates Page Templates Templates: sample pages with “placeholders”

29 Site Template Page Templ. 1 Es: PersonPage Page Templ. 2 Es: CoursePage Page Templ. N Es:GroupPage Page Style 1Page Style nPage Style 2 Homer user editing  This approach is strongly based on the ADM page types Step 3: Presentation Modeling Users work with Templates and Homer generates styles from them

30 Site Generation: Homer Creates Java Programs What’s inside Homer: –an engine for handling schema transformations; Homer Engine: –all intermediate models (ER, Relational...) are seen as subsets of ADM –transformations as views, i.e. algebraic expressions (nested- relational algebra with URL-invention) –view composition Implementation: –HTML or XML with XSL stylesheets; –JSP for dynamic pages, Java programs for static pages.

31 Mapping ADM and DB: Penelope DEFINE PAGE AuthorList AS URL("AuthorList"); UnRegisteredAuthors: LIST-OF (username : TEXT = ; status : TEXT = ; ); RegisteredAuthors: LIST-OF (username : TEXT = ; status : TEXT = ; details : LINK-TO AuthorData (URL( ); anchor : TEXT ="Go to Author page"; ); ); USING reg : (SELECT username FROM Author WHERE status="true" ), unreg : (SELECT username FROM Author WHERE status="false" ); END

32 Modeling applications ADM, Penelope, the methodology, and the tool were all conceived for "read-only"sites we want to extend them to more general sites, still under the "data-intensive" hypothesis

33 Features for modeling applications Management of users: authorization and personalization Phases (and workflows) Actions, mainly associated with links Transactions Nested database updates

34 Management of users: authorization and personalization DEFINE RIGHTS GROUP PCchair IN AuthorData,AuthorList; GROUP Author IN CoAuthorPreRegistration, AuthorRegistration:ONETOONE, AuthorData:ONETOONE;

35 Phases (and workflows) DEFINE TASK Phase0 WITH ConferenceSetup; END ON LINK ConferenceSetup.linkA; DEFINE TASK Phase1 WITH ConferenceData, PCmemberPreRegistration, PCmemberRegistration, PCmemberData, PCmemberList; START ON LINK ConferenceSetup.linkA; DEFINE PAGE PCmemberPreRegistration … EXPIRES ON LINK …

36 Actions ACTION ON LINK ConferenceSetup.setupForm.update; BEGIN INSERT INTO conference VALUES ([title], [date], [place], [submissionDate], [reviewDate], [notificationDate], [contacts], [goals], [attendance], [relatedConferences], [moreInformation]); INSERT INTO track SELECT [tracks.item] FROM [tracks]; INSERT INTO subject SELECT [subjects.item] FROM [subjects]; INSERT INTO evaluationItem SELECT [evaluations.id], [evaluations.item] FROM [evaluations]; COMMIT PUSH PAGE ConferenceSetup; END

37 The Araneus methodology ER NCM RDB ADM Styles Site

38 The Araneus-2 methodology ER NCM RDB ADM i Site ADM Activity D Use Case D UseCase i * *

39 Activity diagram

40 Use Case Notation ("Stereotypes") read-only read-write

41 Use Case Diagram - Phase 0

42 Use Case Diagram - Phase 1

43 Use Case Diagram - Phase 2

44 Use Case Diagram - Phase 3

45 Use Case Diagram - Phase 4

46 Use Case Diagram - Phase 5

47 Use Case Diagram - Phase 6

48 E-R scheme

49 E-R Scheme - part II

50 Relational Scheme

51 NCM data diagram

52 NCM - Phase 0

53 NCM - Phase 1

54 NCM - Phase 2

55 NCM - Phase 3

56 NCM - Phase 4

57 NCM - Phase 5

58 NCM - Phase 6

59 ADM - Conference setup

60 ADM - PC-member registration

61 ADM -Author registration

62 ADM - Paper submission

63 ADM - Paper administration

64 ADM - Paper assignments

65 ADM - Paper interest

66 ADM - Paper review list

67 ADM - Paper download

68 ADM - Reviewer registration

69 ADM - Insert report

70 ADM - Paper statistics

71 ADM - Paper selection

72 ADM - Accepted paper

73 ADM - Home Pages