WebML and WebRatio

WebML
Designing data-, service-
and process-intensive
applications with WebML
Bari, November 24, 2010
Marco Brambilla
Politecnico di Milano and Web Models Srl
http://home.dei.polimi.it/mbrambil
http://twitter.com/MarcoBrambi
http://www.slideshare.net/mbrambil
www.webratio.com

2
marco.brambilla@polimi.it
WebML
Agenda
 WebML models and concepts
 Advanced topics: Web services, BPM, Ajax
 WebRatio 6 BPM
 Industrial cases

WebML
WebML models and concepts
Marco Brambilla
marcobrambi
marcobrambi

4
WebML
Advantages of Modeling approach
A rigorous modeling approach:
 Can reduce development efforts (cost and time)
 Allows a more structured development process
 Produces more usable and coherent final results
 Design models are self-documenting and always up-to-date
projects
Immediate prototyping can be achieved

5
WebML
Target of WebML
 Target: data intensive Web sites
• large amount of data
• interfaces directed to general public
 exploratory
 browsing-oriented
 personalized (1 to 1)
• volatile content, structure, navigation, presentation
 WebML is not the right approach for:
• Small Web sites (Homepages, …)
• Static Web sites

6
WebML
The WebML models
 WebML: a conceptual language for high-level design of data-
intensive web sites
 Models:
• Content: data organization
• Derivation: redundant data definition
• Composition: definition of site pages as set of subpages and
elementary publishing units
• Navigation: definition of links between pages and between units
• Presentation: positioning of the units in the page and definition of
graphical appearance

7
WebML
Preview of WebML concepts
 Site = Content + Composition + Navigation + Presentation
content
navigation +
composition presentationuser models
entities,
relationships
units, pages,
links
site views styles

8
WebML
Development process
Business Requirements
HYPERTEXT DESIGN
DATA DESIGN
ARCHITECTURE DESIGN
REQUIREMENTS SPECIFICATION
IMPLEMENTATIONTESTING & EVALUATION
MAINTAINANCE & EVOLUTION

9
WebML
Data Model
 Simplified Entity-Relationship model
• Binary relationships between entities
• IS-A hierarchies
• Simple typed
attributes in entities
• Derivation model
can be applied for
redundant data
Book
Author Genre
BestSeller

10
WebML
WebML OCL
 Derivation consist of writing expressions called “derivation
queries”
 Queries can be expressed using WebML OCL
 Derivable concepts:
• Entities, relationships, attributes
 Derivation queries can be automatically transformed into SQl
views installed in the database

11
WebML
Example: derived attributes
 Attributes of an entity can be derived by associating to them a
query.
 Four types of derived attributes:
• Constant attribute: affiliation: “Politecnico di Milano”
• Imported attributes: maritalName: Self.husband.lastname
• Aggregate attributes: reservation#: count(Self.reservation)
• Calculated attributes: lastPrice: Self.price*discount
 The Self keyword identifies the current entity in which the
attribute is defined

12
WebML
Hypertext Model
• Q1: what information is published in the hypertext nodes?
• Q2: how are the hypertext nodes connected?
• Q3: how is the hypertext divided into pages served to the user?
• A1: content units (Composition)
• A2: links (Navigation)
• A3: pages (Composition)

13
WebML
Composition: examples of Content Units
DATAUNIT
INDEXUNIT
content
content
To publish information about
A SINGLE object
(e.g. AuthorDetail)
To publish a list of objects
(e.g. IndexOfAuthors)

14
WebML
Composition: examples of Unit rendering
DATAUNIT
INDEXUNIT
Author
first name:XXX
last name:YYY
photo:
Index of Authors
•S. Ceri
•P. Fraternali
•O.Versand
Author
Author

15
WebML
DATAUNIT INDEXUNIT MULTIDATAUNIT
ENTRYUNIT SCROLLERUNIT
entity
[Selector]
Content:
• instances of
an entity
Basic Content Units
entity
[Selector]
entity
[Selector]
entity
[Selector]
MULTICHOICE
entity
[Selector]
Selector:
• set of
conditions
HIERARCHICAL
entity
[Selector]

16
WebML
DATAUNIT INDEXUNIT MULTIDATAUNIT
ENTRYUNIT SCROLLERUNIT
Meaning of Content Units
Author
first name:XXX
last name:YYY
photo:
Index of Authors
•S. Ceri
•P. Fraternali
•O.Versand
All Authors
Browse Authors
5/12: go to
  
1/12
Insert Your Data
•Fname
•Lname
MULTICHOICE
Choose Authors
Ceri
Fraternali
Versand
HIERARCHICAL
Books&Authors
1. Web Applicat.
Ceri
Fraternali
2. Systems
Tannenbaum

17
WebML
Content Units
 A WebML unit is the atomic information publishing element
 It is a “view” defined upon a container of objects:
• All the instances of an entity
• Instances of an Entity that meet a selection condition called selector
unitX
container

18
WebML
Unit input and output
 A unit may need some “context” to be computed
 Each unit exposes input and output parameters
 Input is required to compute the unit itself
• Parameters pre-defined for the unit +
• Other parameters required by the selector of the unit
 Output can be used to compute other unit(s) depending on the current
unit
unitX
entity
[selector (par 1, .., parN)]
IN OUT

19
WebML
Navigation: contextual links
• A contextual link is an oriented connection between two
units (source unit and target unit), normally rendered by
means of anchors or submit buttons
• Purpose of a contextual link:
•Allowing the user to move from one place to another
•Transporting information from one place to another
•Activating a computation (side effect)
AuthorAuthor
source unit target unit

20
WebML
Author
first name:James
last name:Joyce
photo:
Author
[OID=p1]
Book
[author2book(p2)]
Book
[OID=p3]
Book
Title:Ulysses
Price:23$
Cover:
Which author’s books? Which book?
Books of YYY
•Ulysses
•The Dubliners
•Portrait...
Example of links
p1 p2 p3

21
WebML
Automatic Links
•An automatic link passes some default context to the
destination unit immediately after the display of the
source unit, without the user intervention
•Subsequently, the user can change the passed context
by choosing a different object, using the anchor(s)
representing the link
AuthorAuthor
source unit target unitA

22
WebML
Transport Links
Author
Book
[Author2Book]
•A transport link has a default context that is passed to
the target unit immediately after the display of the
source unit, without the user intervention
•The user cannot change the default context and
therefore the link is not rendered with an anchor
source unit target unit

23
WebML
Pages
 A page is a container of one or more pieces of information
shown to the user at the same time
 Nesting of pages is allowed: a page can have sub-pages
 The user navigates a site made of pages
LoginBook Index Catalog

24
WebML
Non contextual links
 A non contextual link is a link between pages
 No context (information) is transported
 The user can browse from a page to another one via an
anchor (e.g., >>Books)
HomePage Book Index

25
WebML
Home Page
 The Home Page is the main page of a site
 It is the first page of the site that the user should see
 Each siteview must contain a page marked as “Home”
HomePage H Book Index

26
WebML
Landmark pages
 Landmark pages: globally visible pages. The user can jump to them from
everywhere in the site view
 It is equivalent to a non contextual link implicitly defined from every other
page in the site view to the landmark page
Authors
Books
L
Book Details
Store Page
Authors
Books
Book Details
Store Page

27
WebML
Areas /Modules
 An area/module is a set of logically homogeneous pages
 Examples of areas:
• Sections of a portal: Sport, Music, Technology, …
• Elements of a data-management system: Products management, News
management, …
 Areas can be nested, so that sub-areas can be defined inside
areas
 Each area should have a DEFAULT PAGE or a DEFAULT SUB-
AREA, to give a meaning to landmark areas and non-
contextual links pointing to areas
Area

28
WebML
Site Views
 A siteview is a set of pages and/or areas forming a coherent
view of the site
 Multiple site views can be defined on the same data model
 Different site views can be published for different types of
users and for different types of output devices
 Site views can be
• Public: everyone can enter
• Private: access control with password protection is enforced

29
WebML
Operation Unit
 Models a generic external operation, or a built-in content
manipulation operation
 Input from one or more incoming links (at least one is
declared as normal link, the others as transport links)
 Two kinds of output links
• OK link if the operation completes correctly
• KO link if the operation fails
 The predefined WebML units can be enriched by adding
custom external operations (e.g. SendMail, …)

30
WebML
Built-in Operations
Delete Unit
Entity
Create Unit
Entity
Modify Unit
Entity
CREATE DELETE MODIFY
Disconnect
Unit
relationship
Connect Unit
relationship
CONNECT DISCONNECT

31
WebML
In/out flows
Create Unit
Entity
value1 attribute1
value2  attribute2
OID of
the new object
KO
OK
Nothing
Value2  attribute1
value1  attribute2
Identifier(s) of the
modified object(s)
Modify Unit
Entity
KO
OK
Identifier(s) of the
object(s) to modify
OIDs of objects to modify

32
WebML
In/out flow: delete
Nothing
OIDs of the
object(s) to delete
Delete Unit
Entity
KO
OK
OIDs of the object(s) to delete
Albums
DeleteAlbum
Album
DeletionError
OK
KO
NotDeleted
Album
DeletionError
NOT DELETED
All the way
1999
Let's talk...
1997
Sing-a-long
1998
Albums
DELETE ALBUMS
OK
KO
All the way
Born in the USA
Imagine
Let's talk ...
Sing-a-long
Anthology
Bridges to Babylon
Del
AlbumIndex
Album
Albums
DELETE ALBUMS
Imagine
Anthology
Bridges to Babylon
Del
Example:

33
WebML
Example
ReviewPage
° Beatles
* Dion
° Prince
One of the most
romantic and
expressive artists
of the nineties.
Result
First name:
Celine
Last name:
Dion
OK
KO
ARTISTSNEW REVIEW ARTIST
ReviewPage
Rev iew
NewReview
AllArtists
Artist
AssignReview
ArtistToRev iew
[Artist.OID = Art ]
[Rev iew.OID = Rev ]
Rev : OID
Art:OID
Result
Artist
[OID = Art]
ArtistDetails
Art: Artist.OID
OK
Rev : Rev iew.OID
KO
Rev iew
[OID=Rev ]
ReviewDetails
Rev : Rev iew.OID
Select an artist to
assign the review: Review :
One of the most
romantic and
expressive artists
of the nineties.
REVIEW

34
WebML
Context Parameters
 WebML Context Parameters allow to achieve this goal in a
simple way
 Designer defines one or more Context parameters.
 A context parameter is defined by:
• Name
• ID
• Duration (User session or Application)
• Value type: can be either:
 A Printable value (integer, string, …)
 An Entity (thus, the parameter can assume an OID value of that entity)
• Starting value [optional]

35
WebML
Set unit
 Unit that allows to SET the value of a parameter
 It is always placed outside a Page
 It has only an incoming link (carrying the value to be assigned
to the parameter)
 It has not outgoing links
Value/OID
ParamName

36
WebML
Get unit
 Unit that allows to RETRIEVE the value of a parameter
 It is always placed inside a Page
 It has only an outgoing link (carrying the value retrieved from
the parameter)
 It has not incoming links
 The retrieved value can be used in any compatible unit
Value/OID
ParamName

37
WebML
Example
NewsPage[L]
CountrySelectionPage [L]
CountryIndex
Country Country
CountryData
LocalNews
News
[Country2News]
SetCountry
CurrCountry
Country
CountryData
GetCountry
CurrCountry
ProductPage [L]
Country
CountryData
LocalProducts
Product
[Country2Product]

38
WebML
Personalization
 Personalization has three facets:
• Access control: login/logout operations for user recognition
• Site view assignement: based on the group a user belong,
some site views are accessible (1 or more site view per Group)
• Page personalization: user or group dependent content

39
WebML
User / Group model
 Each User can belong to one or more Groups (predefined
entities in the structural model)
 Each user has one default Group
 Each group has one associated Siteview
User Group1:N 1:N
1:1 1:N
Module
1:N
1:1
user2group
user2defaultGroup

40
WebML
Login/ Logout
 A site-view may contain a page allowing users to login
 Each secured site-view should allow users to logout
 Dynamic Role Changing
(i.e. group) allowed
Entry Unit Login
Logout
ChangeGroup

41
WebML
Page personalization (User)
 Personalization can be achieved as a result of appropriate
structure design
reservation
userslot
•Hypertext can reflect structure,
and thus provide personalization After login
UserCtxParam
is bound to
“my” identity,
thus the index
shows “my”
reservationsentity:user rel:reservation
Personal Reservations
UserCtxParam

42
WebML
Presentation
 Presentation dealt with along two lines:
• Gallery of default presentation styles applicable to site views or single
pages (with elementary unit positioning on a grid)
 each presentation style is an XSL stylesheet
• Compatibility with best selling tools for presentation editing, for
advanced page design

43
WebML
1.2.e Style guidelines specification
Page grid:
Content positioning:Content positioning:Graphical guidelines:

WebML
Web Services
Marco Brambilla
marcobrambi
marcobrambi

45
WebML
Web services architecture
Service Integration
Service Discovery
Service Publication
Service Description
XML -based Messaging
Transport
BPEL4WS IBM, Microsoft & BEA
WCSI Sun
BPML BPMI.org
WSFL IBM
XLANG Microsoft
UDDI UDDI.org
UDDI UDDI.org
WSDL W3C
SOAP W3C
XML W3C
HTTP W3C

46
WebML
WebML support for web services
 Goal: modeling the interaction between the Web application,
the human users, and the remote systems
 New modeling primitives are required:
• primitives for handling the various classes of service operations
 Run-time support for Web services
• Ability of exchanging messages
• Integration of application data and Web services XML messages
• Support for conversations

47
WebML
Actual implementation within the tool
 Web Service invocations
 Web service publishing

48
WebML
DEMO: the mediator at work
 Receive PO
 Obtain CustomerId
 Create Order
 Send Lines
 Close Order

WebML
BPM
Marco Brambilla
marcobrambi
marcobrambi

50
WebML
Model-driven Development Process
 Manual specification of (extended) BPMN process model
 Automatic transformation of BPMN to WebML
 Possible manual refinement of WebML models
 Automatic running code generation on J2EE platform
50

51
WebML
What is BPM?
 Business Process Modeling aims at defining enterprise
businesses in a (semi)formal way
• More to come in future courses
 BPMN is flow-chart based notation for defining Business
Processes
 The current version is 1.2, with a major revision process for
2.0 in progress
 Covers three different levels of process modeling:
• Process Maps – simple flow charts of the activities
• Process Descriptions – flow charts extended with additional
information, but not enough to fully define actual performance
• Process Models – flow charts extended with enough information so
that the process can be analyzed, simulated, and/or executed

52
WebML
Basic concepts
 Small set of graphical elements to make it easy for business
users as well as developers to understand the flow and the
process.
 Four basic categories of elements compose a business
process diagram (BPD):
• Flow Objects
 Events, Activities, Gateways
• Connecting Objects
 Sequence Flow, Message Flow, Association
• Swimlanes
 Pool, Lane
• Artifacts (Artefacts)
 Data Object, Group, Annotation
• It is also allowed to make a custom type of a Flow Object or an Artifact
to make the diagram more understandable.

53
WebML
Pool and lanes
 A Pool:
• represents a Participant in the Process. A Participant
can be a specific business entity (e.g., a company) or
can be a more general business role (e.g., a buyer,
seller, or manufacturer)
 A Lane:
• Is a sub-partition within a Pool
• Is used to organize and categorize activities within a
Pool.
• Is often used for such things as internal roles (e.g.,
Manager, Associate), systems (e.g., an enterprise
application), an internal department (e.g., shipping,
finance)

54
WebML
Sequence flow
 A Sequence Flow is used to show the order that activities will
be performed in a Process
 The source and target must be one of the following objects:
• Events
• Activities
• Gateways
 A Sequence Flow cannot cross a Sub-Process boundary or a
Pool boundary

55
WebML
BPMN  WebML transformation
 Transformation rules
• finer-grained Application Model, needing few refinements by the designer
 typed activities enables reusable application models
 data dependencies are specified at a higher level
• less errors in Application Model design
• Faster development
55
(1) One control siteview per pool: Human interaction(2) One control serviceview per pool: WS Choreography(3) One site view per lane: user navigation(4) One site view per lane: business logics of activities and gateways(4) One site view per lane: business logics of activities and gateways(5) Orchestration view: a controller component invokes the activities

56
WebML
Process
Metadata
Run-Time
Log
Actors
Data Model

57
WebML
The NEXT unit
• The Next unit encapsulates the process control logic
• It exploits the information stored in the Process Metadata
• It calculates the current process status and the enabled state
transitions
• It needs the following input parameters:
– caseID (the currently executed process instance ID)
– activityInstanceID (the current activity instance ID)
– conditionParameters (the values to evaluate the
conditions)
57
NEXT

58
WebML
Next Unit

WebML
AJAX support
Marco Brambilla
marcobrambi
marcobrambi

60
WebML
Conceptual modeling of AJAX features
 WebML currently covers a limited set of AJAX features
• Major revision foreseen
 Partial page refresh
 Popup windows

61
WebML
Conceptual modeling of AJAX features
 Dynamic tooltips
 Drag and drop

WebML
WebRatio 6 BPM
Marco Brambilla
marcobrambi
marcobrambi

63
WebML
WebRatio 6 BPM
 WebRatio 6 BPM permits you to:
• Model and Document your processes
• Execute and Validate your processes by instantly prototyping
• Developing, Improving and Refining your processes and create a
complete Web application

64
WebML
Automatic Generation of the Appl.
 Starting from the models and rules defined in the previous steps,
WebRatio is able to automatically generate the final application. The
result is:
• standard and open Java Web application, no proprietary runtime
• deployable on any Java Application Server
IBM
WebSphere
Caucho
Resin
Apache
Tomcat
Oracle
Application
Server
JBoss
Application
Server
Process layer
Service
layer
Presentation layer
Data
layer
Integration
layer
Standard Java
Web application
Visual identity
Business layer

65
WebML
When to use WebRatio
 1. Business Process Automation “stand-alone”
 2. Especially: custom Web application with integrated BPM
describing the core company functions, such as:
• Web Front-End for a legacy information system (ERP)
• Other enterprise IS such as CRM, Ticketing, HR, ...
• Web portal with CMS
• E-Business solutions in B2C or B2B scenarios
65

66
WebML
WebRatio functionalities
 Content model design
 Business proces model design
 Data derivation (Derivation Wizard)
 Hypertext model design (siteviews)
 Consistency checks (warnings)
 Mapping onto a datasource
 Units positioning in the pages
 Automatic web site generation
 Integration of advanced features (BPM, Web services, AJAX)

WebML
Industrial cases
Marco Brambilla
Politecnico di Milano and Web Models Srl

68
WebML
Acer Euro CMS
 B2C + CMS Web applications initially for 14 EU countries
(year 2000)
 Corporate news, Product technical & commercial data,
Service & Partner area, Where to Buy…
 Multilingual, multi-actor, distributed workflows for local and
central PMs, local and central MarCom managers
 ... and a: very limited Time to Market (7 weeks!!)

69
WebML
Size & effort
DEGREE OF AUTOMATION
Number of manually written SQL statements 17(SQL constraints)
Percentage of automatically generated SQL code 96%
Number of manually written/adapted Java classes /JSP templates 10% JSP templates
manually adapted
Percentage of automatically generated Java and JSP code 90% JSP templates,
100% Java classes
COST AND ROI
Total cost of software development of first version 75.000 €
HW, SW licenses, and connectivity cost of first version 70.000 € (db server
license)
Return on investment of first version 12-15 months
Average effort of extension to one additional country 0,5 staff-months
Average cost of extension to one additional country 7.500 €
Average ROI of extension to one additional country 2 months
PRODUCTIVITY
Number of function points 177 (B2C web site)
+ 612 (CMS) = 789
Average number of function points delivered per staff-month 131,5

70
WebML
Critical Considerations (continued)
 On the negative side..
• Acer estimates that it took from 4 to 6 months to have fully
productive developers with MDD, WebML, and WebRatio.
 ..but..
• The initial investment in human capital required by MDD pays off in
the mid term
 MDD benefits testing, maintenance, and evolution (which account for
over 60% of the total lifecycle cost)
 reasoning on the system is far more effective at the conceptual level
Served Contries and Applications
4 4 4 5 5
17
24
32
41
56
17
21
24
28
31
0
10
20
30
40
50
60
2001 2002 2003 2004 2005
Year
Units
Number of developers
Number of
maintained
applications
Number of served
countries

71
WebML
Major European bank – large BPM case
 The pilot application for the first country (planned to be
extended to 10 more) covers
• 52 business processes
• 1,100 activities
• 30 user roles.
• Application load of 300 registered users, with 100,000 cases / 2 MLN
activities per month
 The development team comprised
• 14 staff members from three organizations
• total effort amounting to 2551 man days, spent in 375 elapsed days

72
WebML
Major European bank – large BPM case
 Distribution of effort:
• 12% for business process analysis and re-engineering,
• 6% for BP modeling according to BPMN,
• 12% for wrapping existing legacy procedures as services accessible
through SOA and BP orchestration,
• 5% for designing the support interfaces for the BPM
• 55% for the design and refinement of the application models that
implement the logic of the activities
• 10% for the design of collateral application for increasing usability and
employee productivity (data look-ups, etc).
 Central role played by the detailed application design
 Main benefits were
• Rapid prototyping, thanks to which 4 major prototypes and 35 minor releases
• Support of teamwork, which allowed 14 contributors from 3 different
organization to work together

73
WebML
References and useful links
 WebML Site (http://www.webml.org)
 Audio lessons
 Teaching materials (slides)
 Solved exercises and examples
 Research papers
 WebRatio Site (http://www.webratio.com)
 Download of the tool
 WebRatio GoogleGroup (https://groups.google.com/group/webratio)
 WebRatio Official Wiki (http://wiki.webratio.com)
 Getting started
 Specific technical articles
• BPMN Official Site (http://www.bpmn.org/)
• My research blog (http://marcobrambi.blogspot.com)

74
WebML
Thanks
http://twitter.com/MarcoBrambi
http://www.slideshare.net/mbrambil
 For comments or questions:
Marco Brambilla
Politecnico di Milano
Dipartimento di Elettronica e Informazione
mbrambil@elet.polimi.it

WebML and WebRatio

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