WSDL describes a service interface Not sufficient: many other aspects of a service needs to be modeled Policies generally define the other

Size: px

Start display at page:

Download "WSDL describes a service interface Not sufficient: many other aspects of a service needs to be modeled Policies generally define the other"

Lucy Hardy
6 years ago
Views:

2 WSDL describes a service interface Not sufficient: many other aspects of a service needs to be modeled Policies generally define the other requirements, constraints, and properties of a service

3 <soap:envelope> <soap:header> <wsa:to> <wsa:action> </wsa:action> </soap:header> <soap:body>...</soap:body> </soap:envelope>

4 <Policy> <wsap:usingaddressing /> </Policy> policy assertion

5 <Policy> <wsap:usingaddressing /> <sp:transportbinding>... </sp:transportbinding> </Policy>

6 <Policy> <ExactlyOne> <sp:transportbinding>... </sp:transportbinding> <sp:asymmetricbinding>... </sp:asymmetricbinding > </ExactlyOne> </Policy>

7 <Policy> <All> <wsap:usingaddressing /> <sp:transportbinding>... </sp:transportbinding> </All> </Policy>

8 <Policy> <mtom:optimizedmimeserialization wsp:optional="true"/ <ExactlyOne> <sp:transportbinding>... </sp:transportbinding> <sp:asymmetricbinding>... </sp:asymmetricbinding > </ExactlyOne> </Policy> Capability, not requirements

9 <sp:transportbinding> <Policy> <sp:transporttoken> <Policy> <sp:httpstoken RequireClientCertificate="false" /> </Policy> </sp:transporttoken> <sp:algorithmsuite> <Policy> <sp:basic256rsa15 /> </Policy> </sp:algorithmsuite>... </Policy> </sp:transportbinding>

10 <Policy wsu:id="common"> <mtom:optimizedmimeserialization wsp:optional="true"/> <wsap:usingaddressing /> </Policy> <Policy Name:= /common"> <mtom:optimizedmimeserialization wsp:optional="true"/> <wsap:usingaddressing /> </Policy> Wsu:Id and Name ID is relative. Refer as Name: absolute http..xml/#common

11 <Policy wsu:id="secure"> <All> <PolicyReference URI= " /> <ExactlyOne> <sp:transportbinding>...</sp:transportbinding> <sp:asymmetricbinding>...</sp:asymmetricbinding > </ExactlyOne> </All> </Policy>

12 <Policy> <ExactlyOne> <All> <sp:transportbinding>...</sp:transportbinding> </All> <All> <sp:asymmetricbinding>...</sp:asymmetricbinding > </All> </ExactlyOne> </Policy> Disjunction of conjunctions

13 What happens if we attach many policies? Maybe to different WSDL elements? Conjunction of policies In normal form, it is the cartesian product

A family of related specs: WS Policy defines the base syntax WS PolicyAssertions contains a set of common message assertions WS PolicyAttachment describes how to

14 A family of related specs: WS Policy defines the base syntax WS PolicyAssertions contains a set of common message assertions WS PolicyAttachment describes how to attach policies to WSDL contracts and UDDI entities WS SecurityPolicy contains security assertions Etc... WS-Policy WS-PolicyAssertions WS-PolicyAttachment WS-SecurityPolicy

15 Can attach policies to various WSDL elements E.g. to a message, operation, port, binding, or service The attachment point defines the scope of the policy Think about modularization and reuse

16 <wsdl:binding name="securebinding" > <PolicyReference URI="#secure" /> <wsdl:operation name="getrealquote" >...</wsdl:operation>... </wsdl:binding>

17 In a separate part or doc, specify which policy is attached to what <wsp:policyattachment> <wsp:appliesto> <wsa:endpointreference xmlns:fabrikam="..." > </wsa:endpointreference> </wsp:appliesto> <wsp:policyreference URI=" /> </wsp:policyattachment>

18 TextEncoding assertions (character sets) Language Version of WS specs Predicates on messages

19 <wsp:exactlyone> <wsp:language wsp:usage="wsp:required" wsp:preference="10 Language="da"/> <wsp:language wsp:usage="wsp:required" wsp:preference="7 Language="en-gb"/> <wsp:language wsp:usage="wsp:required" wsp:preference="1 Language="en"/> </wsp:exactlyone>

20 Assertions relate to security tokens, message integrity, message confidentiality, message visibility to SOAP intermediaries, constraints on the security header age of a message

21 <wsdl:definitions> <wsp:usingpolicy Required="true"/> <wsp:policy Id="Auth.xml> <wssp:identity> <wssp:supportedtokens> <wssp:securitytoken TokenType=" open.org/wss/ 2004/01/oasis wss x509 token profile 1.0#X509v3"> </wssp:securitytoken> </wssp:supportedtokens> </wssp:identity> </wsp:policy> </wsdl:definitions>

22 Policies Optional, conjunctive Attaching policies to WSDL Combining policies Assertions, security

23 Ws policy intro us/library/ ms aspx Specs Web Services Policy Framework (WS Policy), current version v policy/

25 No guaranteed delivery No ordered delivery No approach to handling delivery failures Solutions WS Reliability (OASIS standard, nov 2004) WS ReliableMessaging

26 Goal: enable two applications to communicate in a reliable way Protocols handled by the middleware

27 App App m WSRM component M+rm acks m WSRM component

28 AtMostOnce: messages delivered once, without duplication. Messages might be lost AtLeastOnce: Each message sent will be delivered, or an error is raised. Messages might be sent more than once in order to ensure that the message arrives. ExactlyOnce: The messages are delivered once, and once only. Failure to acknowledge the messages raises an error. InOrder: The messages are sent in order. If the order is not retained, then an error is raised. this assurance does not imply that the message cannot be resent if necessary.

29 A sequence is created for every set of message exchanges that needs to be reliable (e.g., in order) Sequence has URI, and incremental number The middleware takes care of inserting the headers, sending acks for each message Ack returns ranges of message numbers Source verifies correspondence

31 <wsrm:createsequence> <wsrm:acksto>endpoint</wsrm:acksto> <wsrm:expires>800</wsrm:expires> </wsrm:createsequence> <wsrm:createsequenceresponse> <wsrm:identifier>uri</wsrm:identifier> <wsrm:expires>500</wsrm:expires> </wsrm:createsequenceresponse>

32 To request a sequence from the destination, the source sends a message with an embedded CreateSequence header block. This provides the following information: An acknowledgement endpoint An expiry duration An optional sequence offer This can be used for two way communication. A security token You can use it to validate messages between the source and destination, as supported by WS Security

33 <wsrm:sequence> <wsrm:identifier>sequenceuri</wsrm:identifier> <wsrm:messagenumber>1</wsrm:messagenumber> </wsrm:sequence> <wsrm:sequenceacknowledgement> <wsrm:identifier>sequenceuri</wsrm:identifier> <wsrm:acknowledgementrange Upper= 3" Lower= 2"/> </wsrm:sequenceacknowledgement> <wsrm:sequence> <wsrm:identifier>sequenceuri</wsrm:identifier> <wsrm:messagenumber>4</wsrm:messagenumber> <wsrm:lastmessage/> </wsrm:sequence>

35 SOAP does not provide a standard way to specify where a message is going, where to respond, or where to report an error Left to the transport Also, it does not specify correlation! Incorporate message addressing information into soap messages

36 Web Services Addressing 1.0 Core W3C Recommendation 9 May 2006 Web Services Addressing 1.0 SOAP Binding W3C Recommendation 9 May 2006 Web Services Addressing 1.0 Metadata W3C Working Draft February 2007

37 Defines endpoint references and message addressing properties endpoint references: info needed to access an endpoint URI Addressing parameters (see bindings) Quality information (metadata) <wsa:endpointreference xmlns:wsa=" addressing"> <wsa:address> </wsa:endpointreference>

<S:Header> <wsa:messageid>http://example.com/someuniquestring</wsa:messageid> <wsa:replyto> <wsa:address>http://example.

38 <S:Header> <wsa:messageid> <wsa:replyto> <wsa:address> </wsa:replyto> <wsa:action> </S:Header> <S:Header> <wsa:messageid> <wsa:relatesto> <wsa:to> <wsa:action> </S:Header> </S:Envelope>

39 How to define addressing properties in WSDL docs? Addressing assertion, specified as ws policy The meaning of this assertion, when present in a policy alternative, is that WS Addressing is required to communicate with the subject wsp:optional="true if I support but do not require

Addressing http://www.w3.org/2002/ws/addr/ See core and metadata specs Short desc from BEA: http://dev2dev.bea.com/pub/a/2005/01/ ws_addressing_intro.

40 Addressing See core and metadata specs Short desc from BEA: ws_addressing_intro.html Reliable messaging Ws reliablemessaging (non std) us/library/ms aspx Ws reliability (std) open.org/committees/wsrm/

41 Defines a way for supporting coordination protocols It is a meta specification, a generic way to define actual coordination mechanisms

42 A method for informing parties about which ROLE they should play in a conversation A method for informing parties about the port of a service participating to a conversation A method for transporting coordination contexts into soap headers

43 Coordination protocol set of rules governing the conversation (e.g., 2PC prepare/ commit, or our business protocols ) Coordination type A set of related protocols (e.g., prepare/commit + outcome notification) An instance of a type can include several instances of each protocol Coordination context Data structure (called coordination) marking messages belonging to the same instance of the coordination type

44 Activation A participant requests a new coordination context. A new instance is created Registration A participant declares to the coordinator that it is a participant Interactions These are protocol specific Note: activation and registration are general (horizontal)

45 central coordination distributed coordination Copyright Springer Verlag Berlin Heidelberg 2004

46 Web service CreateCoordinationContext coordination type - reply address ActivationCoordinatorPortType ActivationRequestorPortType CreateCoordinationContextResponse coordination context - identifier - coordination type - registration address -... coordinator Copyright Springer Verlag Berlin Heidelberg 2004

47 Needed to inform about protocol-specific interfaces Web service register protocol identifier - registration callback address - participant service address registerresponse coordinator protocol-handling address RegistrationCoordinatorPortType RegistrationRequestorPortType coordinator

48 Not defined by ws-coord. It is assumed that coord and participants will have protocol-specific port types Web service protocol-specific messages from participant to coordinator XParticipantPortType protocol-specific messages from coordinator to participant XCoordinatorPortType coordinator Copyright Springer Verlag Berlin Heidelberg 2004

49 Web service A coordinator C Web service B activation participant protocol participant activation coordinator protocol coordinator activation participant protocol participant registration participant Web service implementation registration coordinator Web service implementation registration participant 1. create CC 2. X1 3. register 4. protocol coordinator 5. operational message 6. register 7. protocol coordinator 8. protocol-specific message 9. protocol-specific message Copyright Springer Verlag Berlin Heidelberg 2004

50 Web service A coordinator C a Web service B coordinator C b 1. create CC 2. X1 3. register 4. protocol coordinator 5. operational message 6. create CC 7. X2 8. register 9. register 12. protocol message 14. protocol message 10. protocol coordinator 11. protocol coordinator 13. protocol message 15. protocol message Copyright Springer Verlag Berlin Heidelberg 2004

51 Coordination context Activation and registration interfaces/ protocols Architecture for centralized and distributed coordination

53 Distributed transaction management Elements of 2PC Elements of long running transactions

54 Set of protocol specs Aug 2005, Microsoft, IBM, BEA, others Built on top of WS Coord Components: Atomic transactions Coordinates short duration activities Business activities For long running activities

55 Leverages WS Coordination: Defines a coordination type to support atomic transactions. Create a new atomic transaction CoordinationContext Add an interposed coordinator to an existing transaction. Propagate the CoordinationContext in messages between web services. Register for participation in coordination protocols, depending on the participant's role in the activity. Protocols include Completion, PhaseZero, 2PC and OutcomeNotification.

56 Participant tells coord to abort or commit Coordinator communicates decision to participant

57 Volatile: After receiving commit request, coord sends prepare invitations. All participant registered for this protocol to answer before any durable2pc participant is contacted Participants not required to be notified of outcome Durable: After the above, the durable participants are involved

58 Also based on WS C Saga like semantics: actions applied and committed. If needed, they are compensated

59 May consume many resources over a long duration. There may be a significant number of atomic transactions involved. Individual tasks within a business activity can be seen prior to the completion of the business activity. Exception handling mechanisms may require business logic to reverse the effects of a previously completed task. Participants in a business activity may be in different domains of trust where all trust relationships are established explicitly.

60 AtomicOutcome: all participants close or compensate MixedOutcome: results may differ

61 Messages sent to coordinator: Completed: coord replies with close or compensate Fault: coord replies with faulted Compensated, Closed, Canceled, Exit Messages sent to participants: Close, Cancel, Compensate, Exited Both accept: getstatus and Status

62 Same as above, but coord can tell participant that work is complete (no more work to be done)

63 WS Coordination ftp://www6.software.ibm.com/software/ developer/library/ws Coordination.pdf Atomic transactions ftp://www6.software.ibm.com/software/ developer/library/ws AtomicTransaction.pdf Business activity ftp://www6.software.ibm.com/software/ developer/library/ws BusinessActivity.pdf

Web Services Coordination and Transactions

Web Services Coordination and Transactions Kapitel 11 1 Motivation Need to coordinate (sets of) activities or applications Distributed Running on different platforms using local coordinators Example Reach