Windows Communication Foundation Top to Bottom Video Note

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WCF Security

Basic Concept:

                -MutualAuthentication: sender and receiver to identity one another
                -Authorization:rights I have
                -Confidentiality:view/hide information base on my permission
                -Integrity: messagenot be altered(Note: use singature)
                -Reliablility:preventing replay and Dos

Transfer Security
                -Transport level
                -Message level
                                -Web Services Security(WS*)

Transport Security
                -Case: (intranet) +use transport security + netTCPBinding if behind firewall

Message Security
                -Case: (interenet)+ use message security+ wsHttpBinding

Protection Level(by default - encrpt and sign)
                -Transport Level
                                -TCP or Namepipe or MSMQ - protection Level can bethrottle to only "encrypt" or "sign"
                                -SSL, protectionLevel always be "encrypt andsign"
                -Message Level
                                -partial message body protection && minimum protectinon level
                                                e.g:[OperationContract(ProtectionLevel=ProtectionLevel.Sign)]
                                                               -set the miniumprotectinon level

Client Credentails
                -Windows
                -Username andpassword
                -X.509 certificate
                -SAML (FederationSecurity, Single Sign On)

Service Credentails
                -Windows
                -X.509 certificate
                *When client usewindows credentails, so does the service
                *When client usethird-party credentails, service must provide a certificate
                                -to pretect transfer and identify service itself

Intranet
                -usually useWindows credentails
                -usually NOT ALLOWImpersonation
                                -e.g.:
                               -in intranet: user number is limit, so not needimpersonation to retrive resource
                                -in internet: user number is unlimit, usuallyimpersonate to IIS, IUSER_XXX to retrive resource

Impersonation
                -Service
                                -[OperationBehaviorAttribute]
                                                -e.g.:[OperationBehaviorAttribute(Impersonation=ImpersonationOption.NotAllowed)]
                                -ServiceAuthorization behavior
                                                -e.g.:<serviceAuthoriaztionimpersonateCallerForAllOperations=false/>
                -Client
                                -TokenImpersonationLevel
                                                -e.g.:proxy.ClientCredentials.windows.AllowedImpersonationLevel=
                                               TokenImpersonationLevel.Identification
                                                               -.None
                                                               -.Anonymous
                                                               -.Identification
                                                               -.Impersonation=>use local account, service side account
                                                               -.Delegation=>use remote account, client side account


Service Certificate
                -e.g.:<serviceCredentails>
                                                <serviceCertificatefindValue="subjectkey" storeLocation=""storeName="" x509FindTYpe=""/>
Client Certificate
                -e.g.:<clientCredentails>
                                                               <clientCretificatefindVluae="subjectkey" storeLocation=""storeName="" x509FindTYpe=""
Negotiation
                -get public key innegotiation exchange,not need to install service cert in client
                - Windows - SPNego
                - Certificate -TLSNego

Secure Sessions
                -Reduce every call to pass crendentail to service, authenticate client once
                -Security contexttoken(SCT) generateed for authentication and message protection
                                -e.g.:<securitymode="Message"><messageclientCredentailType="UserName"establishSecurityContext="false"/>

(Learning WCF) Authentication, Authorization, andIdentities
                ServiceSecurityContext
                                -PrimaryIdentity
                                                -Contains areference to an IIdentity type such as WindowsIdentity or GenericIdentity,representing the authenticated caller.
                                -WindowsIdentity

Contract Versioning

Versioning Issue

-Once published, the WSDL contract is final

Version Tolerance (by default)

-Client send exact data, Servicethrow it away by default

-Forgive missing field, if the field is non-required data

-All aboveare handled by DataContractSerializer

-Reasonable changes can be made without impact to existing clients and service

e.g.: remove non-required fileds, add new operation

IExtensibleDataObject

-Client send exact data, Service preserve data and send back to client

-Servicereturn information with exact fields, Client preserve data and send back toservice

-IExtensibleDataObjectis use memory dictionary

-Implementation

e.g.:

publicclass LinkItem : IExtensibleDataObject

{

privateExtensionData m_extensionData;

publicExtensionDataObject ExtensionData

{

get{returnm_extensionData;}

set{m_extensionData=value;}

}

Disabling IExtensibleDataObject

-<ServiceBehavior>

<behaviorname="serviceBehavor">

<dataContractSerializerignoreExtensionDataObject="true"/>

[ServiceBehavior(IgnoreExtensionDataObject=true))]

public class TestService:

{

}

Versioning Strategies

-StrictVersioning

-PracticalVersioning

-backwardand forward compatibility

Versioning Approach: Inheritance

-e.g.:

[ServiceContract(Name="ServiceContract",Namespace="http://myservice

/2006/06")]

publicinterface IServiceA

{

[OperationContract]

stringOperation1();

[OperationContract]

stringOperation2();

}

[ServiceContract(Name="ServiceContract",Namespace="http://myservice

/2006/07")]

publicinterface IServiceA_2:IServiceA

{

[OperationContract]

stringOperation3();

}

Versioning Approach: Semi=strict (Add new Endpoint to trackusage)

Versioning Approach: No Inheritance

-e.g.:

[ServiceContract(Name="ServiceContract",Namespace="http://myservice

/2006/06")]

publicinterface IServiceA

{

[OperationContract]

stringOperation1();

[OperationContract]

stringOperation2();

}

[ServiceContract(Name="ServiceContract",Namespace="http://myservice

/2006/07")]

publicinterface IServiceA_2

{

[OperationContract]

stringOperation1();

[OperationContract]

stringOperation2();

[OperationContract]

stringOperation3();

}

Data Contract Versioning

-Neverremove/Add requird field

-Don'tchange namespace

Transaction

WCF provides reliability features:

-Reliablesession

-Supportfor transactions

-Durablequeued messaging

ACID properties

-Atomic

-Consistent

-Isolated

-Durable

Two-Phase Commit Protocol

-Phase 1

-Coordinatorask each RM(Resource managers) to commit

-EachRM votes to commit or abort

-Coordinatorcollects all votes and decides outcome

-Phase 2

-Coordinatorasks RM to commit or abort

-RMacknoledges completion if commit request

Durable vs. Volatile RM

-A durableRM can save information durating Phase 1of 2PC towithstand equipment outages

-e.g:SQL Server Database

-Survivemachine restarts

-A volatileRM operations on data in memory

-e.g:transactional dictionary

-Cannotsurvive machine restarts

Resource Manager

-LTM(Lightweight Transaction Manager)

-NOuse distributor coordinator

-KTM(Kernal Transaction Manager)

-DTC(Distributed Transaction Coordinator)

-Corssapp domain, process, and machine boundaries

WCF Transactions

-Enabletransacgtion flow on the binding

e.g:

<bindingtransactionFlow="true" transactionProtocol="OleTransactions"/>

+flowtransaction from client to service, or service to other service

[TransactionFlow(TransactionFlowOption.Allowed)]

publicvoid SetCount1(){...}

-Transactionprotocal must be selected

-Client call service operations specify support for transactions

e.g.:

using(TransactionScopescope=new TransactionScope(TransactionScopeOption.Required))

{

...

}

-Serviceoperations must explicitly agree to join a transaction or create one

e.g.:

[OpeationBehavior(TransactionScopeRequired=true,TransactionAutoComplete=true)]

[TransactionFlow(TransactionFlowOption.Allowed)]

publicvoid SetCount1(){...}

[OpeationBehavior(TransactionScopeRequired=true)]

[TransactionFlow(TransactionFlowOption.Allowed)]

publicvoid SetCount2(){...}

Enabling Transaction Flow

-TransactionFlow is disable by default

Transaction Flow Options

-NotAllowed

-e.g.:notallowed untrust client to flow their transaction

-protectservice in internet

-Mandatory

-inthis case, client need to have using "TransactionScope"

-Allowed

Transaction Protocol Options

-OleTransactions:crossprocess and network boundaries

-NamedPipes and TCP default

-WSAtomicTransaction11:cross service boundaries over HTTP

-onlyoption for HTTP

Timeout

-e.g.:

<serviceTimeoutstransactionTimeout="00:00:01">

Isolation Level

Reliable Message

Reliable Sessions

-Delivery guarantees

-Deliveryexactly once

-Deliverin order(if desired)

Enabling Reliable Sessions

e.g.:

<reliableSessionenable="true" ordered="true"inactivityTimeout="00:10:00"/>

<reliableSessionenable="true" ordered="true"inactivityTimeout="00:10:00"/>

**Make sure message arrive at service even is one way,otherwise it will block client

WCF Architecture

-A reliablesession is established at the channel layer

-RM(reliableMessageing) Buffers at both ends manage reliablility

-Deliverynotifications handled by acknowledgements send to client channel

-missing acknowledgements will re-try of number of time

WS-RM Message

-CreateSequence

-CreateSequence Response

-SequenceAcknowledgement

-LastMessage

-TerminateSequence

-ACK isreturned with HTTP responses, or in separate message over TCP

Reliable Sessions Configuration

-AcknowledgementInterval

-FlowControl

-howmany room we have in buffer

-*InactivityTimeout

-MaxPending Channels

-Max RetryCount

-MaxTransfer Size Window

-*Ordered

Requiring Ordered Delivery

-e.g:

[ServiceContract]

[DeliveryRequirement(RequireOrderedDelivery=true,TargetContract=Typeof(MyMessage.IMyMessage)]

Retry Attempts

Session Identifiler

-A unqiuesession identifier is required to correlate message between client and servicechannels

SessionTimeout

-receiveTimeout

-reliableSession-inactivityTimeout

-Take theless value of above two