turning portlets into services: the consumer profile oscar díaz, salvador trujillo, sandy pérez...

Turning Portlets into Services: The Consumer Profile

Oscar Díaz, Salvador Trujillo, Sandy PérezONEKIN Research group

University of the Basque Country San Sebastián (Spain)

May 11th, 2007

The 16th International World Wide Web Conference

O. Díaz, S. Trujillo & S. Pérez 2

Outline

Problem statement: portlet variability

What can vary

When can it vary

How is it supported


Service Oriented Architecture

“SOA can be regarded as a style of information systems architecture that enables the creation of applications that are built by combining loosely coupled and interoperable services”

© Elements of SOA, by Dirk Krafzig, Karl Banke, and Dirk Slama. Enterprise SOA.Prentice Hall,2005


Portlet-based SOA

Portlets can be the enablers of SOA at the front end

“Front-end”SOA

PORTLETPORTLET

REPOSITORYPORTLET BUS

SOA

PORTLETPORTLET



From Web Services to Portlets

XMLRequest

XMLResponse

Web Services Client

Application User Interface

WS Proxy

2nd Hand Car Database

Search for Cars

Car Search Service

request

Client application

Portlet

User Interface

Business Logic

response

SOA

PORTLETPORTLET



Portlet repository

Portlet Swap: jboss.org

Portlet Exchange: portletexchange.com

Open Source Portlet Repository Project (2006):• “a library of ready-to-run applications that you

can download and deploy directly into your portal with, in most cases, no additional setups or configurations”

SOA

PORTLETPORTLET



“Portlet bus”SOA

PORTLETPORTLET


Portlet interoperability based on the WSRP standard

The portal as the most popular portlet consumer

WebSphere portlet

Plumptree portlet

Oracle portlet

eXo portal


WSRP protocol (registration)

Portlet Consumer WSRP ProducergetServiceDescription

As an unregistered consumer

MetadataMetadata indicates that registration is required, and certain data is required for registration

registerWith registration data

registerRegistration context

Unique to the consumer

getServiceDescriptionAs a registered consumer

Metadata + Offered portlets

SOA

PORTLETPORTLET



Portlets as Web components (reusable)

MyBrowserEnd User 1

MyBrowserEnd User 2

Portal 1Consumer 1

Portal 2Consumer 2

HTTP

HTTP

Producer A

Producer B

Producer L

SOAP

SOA

PORTLETPORTLET



But this is not enough …

Portlets are coarse-grained components• They realise full-fledged applications (not just

functions)

The larger the component, the lower the reuse

“front-end”SOA

PORTLETPORTLET


VARIABILITY


Portlet ubiquitousness

The capacity of a component for being customized to the idiosyncrasies of distinct consumer applications

Portlet

Consumer (e.g. a Portal)

SOA

PORTLETPORTLET


VARIABILITY


Outline

Introducting the setting:

portlet variability

What can vary

When can it vary

How is it supported


What can vary

Portlet variations can manifest in any of the three layers: • the presentation layer

– rebranding the rendering with logos and banners, changing the labels and text, changing the entry fields and so on.

• the functional layer– tuning the process to fit the consumer demands.

• the data layer– distinct functionalities will probably require distinct

data.


e.g. presentation-style variants

A portlet output must be aesthetically harmonised with the presentation guidelines of the hosting Portal

WSRP supported

Blue-ish

Green-ish

Red-ish


e.g. functional variants

Previous variants where domain independent

Most often, variations are domain dependent


flightBooking sample case

Domain: an air carrier selling tickets through distinct travel agencies:

Portlet: flightBooking


What can vary on flightBooking?

payment, indicates how travel agencies (portlet consumers) are compensated

checkin, some travel agencies do not allow for this functionality

flightTypes, indicates the focus on domestic or international flights

portletPref, permits the travel agency to tune which trip parameters end users can set a default for


The consumer model

A feature is any characteristic, placed by the carrier and used by the travel agency to describe how the flight booking process should be tailored to the agency’s idiosyncrasies.

The Consumer Model is • a feature model that • captures the variation space for • consumers of a given portlet


Consumer model for the sample case (*)

and alternative or mandatory optional repetitions

1..* *

(*) FODA notation


The Consumer Profile

A Consumer Profile • instantiates the consumer model• for a particular consumer (e.g. Thomas Cook

travel agency).


The consumer profile for Thomas Cook travel agency


Outline


portlet variability

What can vary

When can it vary

How is it supported


When can it vary

When are blue decorators set?

We need to indicate for each feature when it needs to be committed to a particular variant (binding time)


Binding time: portlet setting

configuration time, the decision is set by the portal administrator any time during the lifetime of a running portlet

runtime, the decision is resolved during the enactment of the portlet (e.g. default departure airport)• adaptive: automatically based on the user profile• adaptable: user intervention through the edit

mode


But …

Handling all variants through parameterization would make the implementation too complex

• The resulting code could be very cumbersome to develop and maintain

It is a problem of scalability

Total number of variants (aprox.) = 3 X 2 X 2 X 2 x 2 x 2 = 96 combinations


Moreover …

Features can impact distinct artifacts


Binding time

Configuration time

Runtime:• adaptive• adaptable

Development time, the decision is taken when the portlet is being developed


Annotating the consumer model with binding times


Outline


portlet variability

What can vary

When can it vary

How is it supported


Software Product Line Approach

Shift of focus from a specific portlet to a portlet domain that sets the variation space (feature model)

Two processes• domain engineering is in charge of determining the commonality and

the variability among the portlet family: feature model + core assets• application engineering is responsible for deriving a specific

application portlet

Distinguishing between these processes permits to separate

• construction of the platform for the portlet family• from production of the custom application portlet


Moving Software Product Lines to portlet developmentWhat needs to be changed in this diagram?

Portlet consumer WSRP ProducergetServiceDescription

As an unregistered consumer

MetadataMetadata indicates that registration is required, and certain data is required for registration

registerWith registration data

registerRegistration context

Unique to the consumer

getServiceDescriptionAs a registered consumer

Metadata + Offered portlets


New description parameters to account for the consumer model

Affects getServiceDescription() parameters

WSRP-compliant extension


New registration parameters to account for the consumer profile

Affects register() parameters

WSRP-compliant extension


A new actor: the domain producer

Domain ProducergetServiceDescription

As an unregistered consumer.Metadata

Metadata indicates that registration is required, plus an extension –the consumer model.

registerWith registration data, plus an extension –the consumer profile.

Portal

regiser (Registers the portal.)

Registration ContextUnique to the consumer.

getServiceDescriptionAs a registered consumer.

Metadata + cloned domain portlet


The domain producer

From the portal perspective, it behaves as a conventional portlet provider• where the portal assumes portlets to be

already deployed at the provider

But, if the binding time of a selected feature is “development time” then the portlet is not yet deployed!!!


Hence, behind the curtains…

The Domain Producer needs to:• Generate the application portlet• Deploy the application portlet into the so-called

Application Producer• Consume the application portlet through a locally

deployed “domain portlet” that behaves as a proxy to the application portlet

PortalServerH

TT

P

WS

RP

DomainProducer

WS

RP

WSRP

Domain Portlet

PLFactory

ApplicationProducer

WS

RP

P1

WSRP

WS

RP

P2 P3

P4

Domain Portlet

consumeconsume


Behind the curtains…Domain Producer

getServiceDescriptionAs an unregistered consumer.Metadata

Metadata indicates that registration is required, plus an extension –the consumer model.

registerWith registration data, plus an extension –the consumer profile.

creates the portlet

Portlet handle

Portal PL Factory API Application Producer

java:createPortletthe consumer profile.

ant:stop

deploys the portletant:start

clonePortlet (Clones domain portlet, which is a proxy portlet)setPortletProperties (Updates the wsrp_portlet_handle preference with the returned portlet handle.)

register (Registers the portal.)Registration Context

Unique to the consumer.

getServiceDescriptionAs a registered consumer.

Metadata + cloned domain portlet

Handle cache


To recap …

Setting: • portlets as enablers of SOA at the front-end

Problem statement:• Portlets are coarse-grained components• Reuse requires portlets to be engineered for

variability• Current parameterization approaches are not

enough


Contributions

An SPL approach is presented• WSRP extensions required to accommodate

the consumer profile• A new actor, the Domain Producer is

introduced• Generative SPL techniques required

A prove-of-concept sample case has been developed with WSRP4J


© Yukon valley by Marc Shandro

Oscar Dí[email protected]

Salvador [email protected]

Sandy Pé[email protected]

http://www.onekin.org© Yukon Valley by Marc Shandro

Thanks for your

attention!!

turning portlets into services: the consumer profile oscar díaz, salvador trujillo, sandy pérez...

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