Web Services Coordination

insidiousbehaviorSecurity

Nov 3, 2013 (3 years and 11 months ago)

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Web Services Coordination
Framework

WS
-
CF

http://developers.sun.com/techtopics/webservices/wscaf/wscf.pdf

Presented by: Francisco Martin
-
Recuerda


Francisco Martin
-
Recuerda

2

Overview


Introduction


Architecture


WS
-
CF Coordination Protocols


Open Issues



Francisco Martin
-
Recuerda

3

Introduction


WS
-
CF specifies a software agent to handle context
management through coordinator.


Coordination is necessary for distributed applications
(i.e. Web Services in choreography)


Defines a Web Service Coordinator:


Context Management.


Maintain a repository of participants.


Guarantee that the participants get the results of the
coordinated interaction.


Uses SOAP to encode messages and WSDL to use a
synchronous invocation style for sending requests.

Francisco Martin
-
Recuerda

4

Introduction (II)

WS
-
CF

Web Services Stack

Francisco Martin
-
Recuerda

5

Architecture


Web Service Coordinator:


Provides an interface for the registration of participants and activities.


Disseminates information to a number of participants and guarantees
that all of them get the information.


Manages the context.


Context information can flow inside messages sent to the participants.


A coordinator can be also a participant to another coordinator,
extending the ability to interoperate accross application domain.


Participants:


cooperating Web Services in a composite unit of work


share a common context


Francisco Martin
-
Recuerda

6

Architecture (II)


Activity:


Represent a defined set of tasks with a set of related coordination
actions.


Involved one or more elements (participants that interacts through a
coordinated).


Coordination Service:


Defines and provides a processing pattern (model).


Example: ACID transaction service provides a protocol that defines a
sequence processing: Prepare, Commit and Rollback.


Also defines how activities are coordinated (activities can cooperate
with each other).


Francisco Martin
-
Recuerda

7

Architecture (III)


Protocol Configuration and Negotiation:


Defines a protocol negotiation between web services to
determine which Coordination Service model will be used.


Determines which protocol message exchange will be
used.


Defines a method to communicate the results of a
process.


Defines the message interactions between the coordinator
and its participants.


Unambiguously identied by a URI.

Francisco Martin
-
Recuerda

8

WS
-
CF Coordination Protocols

Coordinator to participant interactions


Messages can start the execution of a particular task
for a specific participant or


Ask for the current state of the execution or


Return or distribute results of the execution of some
process.

Service to coordinator interactions


Basically defines how a service can ask to a
coordinator to register or unregister participants for
an specific activity.

Francisco Martin
-
Recuerda

9

WS
-
CF Coordination Protocols

Client to coordinator


Basically defienes how a client (user) of the
coordination service can obtain the status of the
coordination or ask it to perform coordination.

Interposition


As we mentioned before, coordinator can be also
participants for other coordinator.


Reduces overhead using proxy coordinator (or
subordinate coordinators).

Francisco Martin
-
Recuerda

10

Open Issues


Guarantee security and confidentiality.


Audit trail (log of actions).


Protocol completeness guarantee.


Quality of Service.