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

http://home.dei.polimi.it/mbrambil

http://twitter.com/MarcoBrambi






[email protected]://home.dei.polimi.it/mbrambil

WebML

Agenda

WebML models and concepts Advanced topics: Web services, BPM, Ajax WebRatio 6 BPM Industrial cases



WebML

WebML models and concepts

Marco [email protected]

mailto:[email protected]

http://it.linkedin.com/in/marcobrambi

http://www.twitter.com/MarcoBrambi


WebML

Advantages of Modeling approachA 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

projectsImmediate prototyping can be achieved




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




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




WebML

Preview of WebML concepts Site = Content + Composition + Navigation + Presentation

contentnavigation +composition

presentationuser models

entities,relationships

units, pages,links

site views styles




WebML

Development process

Business Requirements

HYPERTEXT DESIGN

DATA DESIGN

ARCHITECTURE DESIGN

REQUIREMENTS SPECIFICATION

IMPLEMENTATIONTESTING & EVALUATION

MAINTAINANCE & EVOLUTION




WebML

Data Model Simplified Entity-Relationship model

• Binary relationships between entities• IS-A hierarchies• Simple typed

attributes in entities• Derivation model

can be applied forredundant data

Book

Author Genre

BestSeller




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




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




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)




WebML

Composition: examples of Content UnitsDATAUNIT

INDEXUNIT

content

content

To publish information about A SINGLE object(e.g. AuthorDetail)

To publish a list of objects (e.g. IndexOfAuthors)




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




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]




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 Fraternali2. Systems Tannenbaum




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




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




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




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




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




WebML

Transport Links

AuthorBook[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




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




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




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




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




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




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




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, …)




WebML

Built-in Operations

Delete Unit

Entity

Create Unit

Entity

Modify Unit

Entity

CREATE DELETE MODIFY

Disconnect Unit

relationship

Connect Unit

relationship

CONNECT DISCONNECT




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




WebML

In/out flow: delete

NothingOIDs 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 way1999

Let's talk...1997

Sing-a-long

1998

Albums

DELETE ALBUMS

OK

KO

All the way

Born in the USA

ImagineLet's talk ...Sing-a-long

Anthology

Bridges to Babylon

Del

AlbumIndex

Album

Albums

DELETE ALBUMS

Imagine

AnthologyBridges to Babylon

Del

Example:




WebML

Example

Rev iewPage

° Beatles

* Dion

° Prince

One of the mostromantic andexpressive artistsof the nineties.

Result

First name:CelineLast 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.OIDKO

Rev iew[OID=Rev ]

ReviewDetails

Rev : Rev iew.OID

Select an artist toassign the review: Review :

One of the mostromantic andexpressive artistsof the nineties.

REVIEW




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]




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




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




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]




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




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

Module1:N1:1

user2group

user2defaultGroup




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




WebML

Page personalization (User) Personalization can be achieved as a result of appropriate

structure design

reservationuserslot

• 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




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




WebML

1.2.e Style guidelines specificationPage grid:

Content positioning:Content positioning:Graphical guidelines:



WebML

Web Services






WebML

Web services architecture

Service Integration

Service Discovery

Service Publication

Service Description

XML - based Messaging

Transport

BPEL4WS IBM, Microsoft & BEAWCSI SunBPML BPMI.org WSFL IBMXLANG Microsoft

UDDI UDDI.org

UDDI UDDI.org

WSDL W3C

SOAP W3CXML W3C

HTTP W3C




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




WebML

Actual implementation within the tool

Web Service invocations

Web service publishing




WebML

DEMO: the mediator at work Receive PO

Obtain CustomerId

Create Order

Send Lines

Close Order



WebML

BPM






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




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




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.




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)

Pool

Lane

1La

ne 2




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

Task 1

Task 2Task 1




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




WebML

ProcessMetadata

Run-Time

Log

Actors

Data Model




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




WebML

Orchestration

Modules

Next Unit



WebML

AJAX support






WebML

Conceptual modeling of AJAX features WebML currently covers a limited set of AJAX features

• Major revision foreseen Partial page refresh Popup windows




WebML

Conceptual modeling of AJAX features Dynamic tooltips

Drag and drop



WebML

WebRatio 6 BPM






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




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

IBMWebSphere

Caucho Resin

ApacheTomcat

OracleApplication

Server

JBossApplication

Server

Process layer

Servicelayer

Presentation layer

Datalayer

Integrationlayer

Standard JavaWeb application

Visual identity

Business layer




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




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


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!!)




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




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

1724

32

41

56

1721 24

28 31

0

10

20

30

40

50

60

2001 2002 2003 2004 2005

Year

Un

its

Number of developers

Number ofmaintainedapplications

Number of servedcountries




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




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




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)



http://www.webml.org/

http://www.webratio.com/

https://groups.google.com/group/webratio

https://groups.google.com/group/webratio

http://wiki.webratio.com/

http://wiki.webratio.com/

http://www.bpmn.org/

http://www.bpmn.org/

http://marcobrambi.blogspot.com/


WebML

Thanks

http://home.dei.polimi.it/mbrambil http://twitter.com/MarcoBrambi


For comments or questions:Marco BrambillaPolitecnico di MilanoDipartimento di Elettronica e [email protected]












