WSReliableMessaging

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WS-ReliableMessaging

• Yildiray Kabak, METU-SRDC

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Outline

• Introduction
• Reliable Messaging Model
• RM Protocol Elements
• Policy Assertions
• Attaching Policy Assertions to Sequences
• Faults
• Security Considerations
• Example Messages

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Introduction

• It defines a messaging protocol to identify,
  track, and manage the reliable delivery of
  messages between exactly two parties, a source
  and a destination.
• It also defines a SOAP binding that is required
  for interoperability. Additional bindings may be
  defined.

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Introduction

• extensible allowing additional functionality,
  such as security, to be tightly integrated.
• integrates with and complements the WS-Security,
  WS-Policy, and other Web services specifications
• Implementations
• ETTK
• Sandesha (Incubation phase) Axis, MySql
• RM4GS (Reliable Messaging for Grid Services)
  J2EE, Postgres

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Outline

• Introduction
• Reliable Messaging Model
• RM Protocol Elements
• Policy Assertions
• Attaching Policy Assertions to Sequences
• Faults
• Security Considerations
• Example Messages

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Reliable Messaging Model

• Four basic assurances that endpoints can provide
• AtMostOnce (some messages may not be delivered)
• AtLeastOnce (some messages may be delivered more
  than once)
• ExactlyOnce
• InOrder
• Persistence considerations and faults related to
  an endpoint's ability to satisfy the delivery
  assurances are the responsibility of the
  implementation and do not affect the wire
  protocol.

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Reliable Messaging Model
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Reliable Messaging Model

• Preconditions
• RM Source MUST have an endpoint reference of the
  RM Destination endpoint (Addressing)
• RM Source MUST have knowledge of the
  destination's policies (Policy)
• If a secure exchange of messages is required,
  then the RM Source and RM Destination MUST have a
  security context. (Security)
• Invariants (MUSTs)
• Sequence number
• Acknowledgement

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Example Message Exchange
Endpoint A
Endpoint B
Establish Protocol Preconditions (Policy
exchange, endpoint resolution, establishing trust)
Create Sequence
Create Sequence Response (Identifierhttp//fabrik
am.com)
Message 1
Message 2
Message 3, LastMessage
Sequence Acknowledgement (Acknowledgement
Range1,3)
Message 2, AckRequested
Sequence Acknowledgement (Acknowledgement
Range1..3)
Terminate Sequence
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Outline

• Introduction
• Reliable Messaging Model
• RM Protocol Elements
• Policy Assertions
• Attaching Policy Assertions to Sequences
• Faults
• Security Considerations
• Example Messages

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RM Protocol Elements

• ltwsrmSequence ...gt
• ltwsuIdentifiergt URI lt/wsuIdentifiergt
• ltwsrmMessageNumbergt unsignedLong
• lt/wsrmMessageNumbergt
• ltwsrmLastMessage/gt
• ltwsuExpiresgt dateTime lt/wsuExpiresgt
• lt/wsrmSequencegt

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RM Protocol Elements

• ltwsrmSequenceAcknowledgementgt ltwsuIdentifiergtht
  tp//fabrikam123.com/abclt/wsuIdentifiergt
  ltwsrmAcknowledgementRange Upper"10"
  Lower"1"/gt lt/wsrmSequenceAcknowledgementgt
• ltwsrmSequenceAcknowledgementgt ltwsuIdentifiergtht
  tp//fabrikam123.com/abclt/wsuIdentifiergt
  ltwsrmAcknowledgementRange Upper"2" Lower"1"/gt
  ltwsrmAcknowledgementRange Upper"6" Lower"4"/gt
  ltwsrmAcknowledgementRange Upper"10"
  Lower"8"/gt lt/wsrmSequenceAcknowledgementgt
• ltwsrmSequenceAcknowledgementgt ltwsuIdentifiergtht
  tp//fabrikam123.com/abclt/wsuIdentifiergt
  ltwsrmNackgt3lt/wsrmNackgt
• lt/wsrmSequenceAcknowledgementgt

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RM Protocol Elements

• ltwsrmAckRequested ...gt
• ltwsuIdentifiergt URI lt/wsuIdentifiergt
• ltwsrmMessageNumbergt unsignedLong
  lt/wsrmMessageNumbergt lt/wsrmAckRequestedgt

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RM Protocol Elements

• ltwsrmCreateSequence ...gt
• ...
• lt/wsrmCreateSequencegt
• ltwsrmCreateSequenceResponse ...gt
  ltwsuIdentifiergt URI lt/wsuIdentifiergt ...
• lt/wsrmCreateSequenceResponsegt

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RM Protocol Elements

• ltwsrmTerminateSequence ...gt ltwsuIdentifiergt
  URI lt/wsuIdentifiergt
• lt/wsrmTerminateSequencegt

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Outline

• Introduction
• Reliable Messaging Model
• RM Protocol Elements
• Policy Assertions
• Attaching Policy Assertions to Sequences
• Faults
• Security Considerations
• Example Messages

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Policy Assertions

• This specification leverages the WS-Policy family
  of specifications
• to enable an RM Destination endpoint to describe
  and advertise its capabilities and/or
  requirements, and
• to enable an RM Source endpoint to communicate to
  the RM Destination the selected characteristics
  that apply for a given Sequence

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Spec Version

• ltwspSpecVersion wspURI"http//schemas.xmlsoap.o
  rg/ws/2004/03/rm"
• wspUsage"wspRequired"/gt

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Sequence Creation/Expiration

• ltwsrmSequenceCreation ...gt ...
  lt/wsrmSequenceCreationgt
• Normally, Sequence creation is optional. With
  this assertion destination declares it obligatory
• ltwsuExpiresgt2100-01-01T120000.000-0000lt/wsuEx
  piresgt

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Inactivity Timeout/Retransmission Interval

• ltwsrmInactivityTimeout Milliseconds"unsignedLon
  g" ...gt ... lt/wsrmInactivityTimeoutgt
• ltwspPolicygt
• ltwsrmBaseRetransmissionInterval
  wspUsage"wspObserved" Milliseconds"2000"/gt
  ltwsrmExponentialBackoff wspUsage"wspObserved"
  /gt lt/wspPolicygt
• Unacknowledged messages will be retransmitted in
  2 seconds and exponential backoff will be used.

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Outline

• Introduction
• Reliable Messaging Model
• RM Protocol Elements
• Policy Assertions
• Attaching Policy Assertions to Sequences
• Faults
• Security Considerations
• Example Messages

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Attaching Policy Assertions to Sequences

• ltwspPolicyAttachmentgt
• ltwspAppliesTogt
• ltwsrmSequenceRefgt ltwsuIdentifiergthttp/
  /fabrikam123.com/abc
• lt/wsuIdentifiergt
• lt/wsrmSequenceRefgt
• lt/wspAppliesTogt
• ltwspPolicygt
• ltwspSpecVersion wspURI"http//schemas.xmlsoap
  .org/ws/2004/03/rm" wspUsage"wspRequired"/gt
• lt/wspPolicygt ltwspPolicyReference
  Ref"http//schemas.xmlsoap.org/ws/2004/03/rm/base
  TimingProfile.xml"/gt lt/wspPolicyAttachmentgt

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Attaching Policy Assertions to Sequences
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Outline

• Introduction
• Reliable Messaging Model
• RM Protocol Elements
• Policy Assertions
• Attaching Policy Assertions to Sequences
• Faults
• Security Considerations
• Example Messages

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Faults

• SequenceFault
• ltwsrmSequenceFault ...gt
• ltwsrmFaultCodegt Subcode lt/wsrmFaultCodegt ...
  
• lt/wsrmSequenceFaultgt
• When an error occurs, this fault is raised. The
  subcode details the faults.

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Subcodes

• SequenceTerminated (Sender, receiver)
• UnknownSequence (Sender, receiver)
• MessageNumberRollover (sender)
• LastMessageNumberExceeded (receiver)
• SequenceRefused (receiver)
• it cannot begin a requested sequence
• CreateSequenceRefused
• create sequence can not be satisfied

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Outline

• Introduction
• Reliable Messaging Model
• RM Protocol Elements
• Policy Assertions
• Attaching Policy Assertions to Sequences
• Faults
• Security Considerations
• Example Messages

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Security Considerations

• WS-Security
• ltwsrmSequencegt need to be signed together with
  the body
• Before the Sequences, a security context is
  recommended to be established using WS-Trust and
  WS-SecureConversation

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Outline

• Introduction
• Reliable Messaging Model
• RM Protocol Elements
• Policy Assertions
• Attaching Policy Assertions to Sequences
• Faults
• Security Considerations
• Example Messages

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Example Messages
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Example Messages
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Example Messages
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Example Messages
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Example Messages
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Example Messages
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Example Messages
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Example Messages
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Example Messages