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Design Review

• Randy H. Katz, Anthony Joseph, Ion Stoica
• Computer Science Division
• Electrical Engineering and Computer Science
  Department
• University of California, Berkeley
• Berkeley, CA 94720-1776

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The Sahara Project

• Service
• Architecture for
• Heterogeneous
• Access,
• Resources, and
• Applications

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Sahara Research Themes

• New mechanisms, techniques for end-to-end
  services w/ desirable, predictable, enforceable
  properties spanning potentially distrusting
  service providers
• Tech architecture for service composition
  inter-operation across separate admin domains,
  supporting peering brokering, and diverse
  business, value-exchange, access-control models
• Functional elements
• Service discovery
• Service-level agreements
• Service composition under constraints
• Redirection to a service instance
• Performance measurement infrastructure
• Constraints based on performance, access control,
  accounting/billing/settlements
• Service modeling and verification

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Horizontal Service Model
Applications-enabling Services
Processing/Storage Location Placement
Reachability Topology
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Connectivity and Processing
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Goals of the Design Review

• Originally
• Present technical architecture for comment/review
• But,
• Not ready to do so!
• Too early in our thinking for comprehensive
  architecture
• So,
• Snapshot of our current thoughts
• Scenarios of service provision
• Dialog with industry colleagues on essential
  components of architecture and their interactions

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Research QuestionsService Design

• For a given community of users and a given set of
  performance, availability, and administrative
  constraints,
• Service Provisioning Problem How many instances
  of a service are needed?
• Service Placement Problem Where should these
  services be placed?
• Adaptive Services How do these deployments
  change with evolution of the user community and
  variations in usage demand?

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Research QuestionsComposition Over Providers

• Cooperative service placement
• Consider placement from perspective of entire
  community of service providers
• How to achieve best possible placement across
  whole community?
• How do service providers make known their
  services for possible peering/composition with
  other providers (mechanisms of service
  advertisement/service level agreement)?
• How are these offered services verified (service
  agreement verification)? Which service provider
  is responsible?

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Research Questions Spanning Service Providers

• Brokered service placement
• Form own service composition by picking
  choosing among service instances discovered from
  underlying service providers
• How is service quality determined by 3rd-party
  broker (performance verification)?
• How is service composition correctness determined
  by the 3rd-party broker (protocol verification)?

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Research Questions

• Service Identification/Choice Problem
• Given an application (e.g., content
  distribution), which is the best service (e.g.,
  cache/storage resources, transport/interconnection
  connectivity and bandwidth for
  performance-constrained delivery) for supporting
  it?
• Service Selection Problem
• Given provisioning placement of services within
  admin domain, which is best service instance?
• Considering load, distance/latency between
  clients of the service and where the service is
  placed, subscription/billing relationships,
  loyalty/affinity relationships, preferences, etc.

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Service Examples

• Connectivity/Reachability
• Basic Internet routing between ASs
• More sophisticated multicast distribution
  formation
• Performance constrained connectivity/latency and
  bandwidth guarantees (e.g., Clearinghouse/Soft
  QoS)
• Performance monitoring services (distance/latency
  mapping, load collection/balancing across service
  instances)
• Content distribution services cache/storage
  resources, distribution/transport resources

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What is a Service?

• Content transformation services (format
  translators)
• Gateway selection under load and performance
  constraints
• Resource allocation services (e.g., auctions for
  bandwidth, processing, storage)
• Mobility services (e.g., device ensembles)
• Who is allowed to invoke a service
  Authentication, Accounting, Access Control
• Payment for services billing, financial
  clearinghouses
• Interworking services across administrative
  domains/different technologies

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Some Starting SAHARA Assumptions

• Dynamic confederations to better share resources
  deploy access/achieve regional coverage more
  rapidly
• Scarce resources efficiently allocated using
  dynamic market-driven mechanisms
• Trusted third partners manage resource
  marketplace in a fair, unbiased, audited and
  verifiable basis
• Vertical stovepipe replaced by horizontally
  organized multi-providers, open to increased
  competition and more efficient allocation of
  resources
• Sanity Check?

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Implications for Architectural Elements

• Open service/resource allocation model
• Independent service creation, establishment,
  placement, in overlapping domains 
• Resources, capabilities, status
  described/exchanged amongst confederates, via
  enhanced capability negotiation
• Allocation based on economic methods, such as
  congestion pricing, dynamic marketplaces/auctions
• Trust management among participants, based on
  trusted third party monitors

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Implications for Architectural Elements

• Forming dynamic confederations
• Discovering potential confederates
• Establishing trust relationships
• Managing transitive trust relationships levels
  of transparency
• Not all confederates need be competitors--heteroge
  neous, collocated access networks to better
  support applications

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Architectural Elements

• Alternative View Service Brokering
• Dynamically construct overlays on component
  services provided by underlying service providers
• E.g., overlay network segments with desirable
  performance attributes
• E.g., construct end-to-end multicast trees from
  subtrees in different service provider clouds
• Redirect to alternative service instances
• E.g., choose instance based on distance, network
  load, server load, trust relationships,
  resilience to network failure,

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TINA Reference Model

• Separate
• apps from exec environ
• service-specific from control
• Generic (Common) Objects Service-Specific
  Objects
• Session duration-based context for processes
  provisioning a service
• Access session (authen-tication, service
  selection)
• Service session
• User service session (user state, resources)
• Provider service session (service logic)
• Comm session abstract view of net connections

Service
Generic Mgmt Control
Applications
Objects
Sessions
Trans- port
Distributed ProcessingEnvironment
Network Environment
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TINA Reference Model

• Business Model
• Roles/entities their relationships while
  participating in service provisioning
• E.g., consumer, retailer, broker, 3rd party
  provider, content provider, connectivity provider
• Information Model
• Information-bearing entities
• E.g., user and service profiles
• Computational Model
• Computational objects their relationships

Service
Generic Mgmt Control
B u s i n e s s M o d e l
I n f o r m a t i o n M o d e l
C o m p u t a t i o n a l M o d e l
Applications
Objects
Sessions
Trans- port
Distributed ProcessingEnvironment
Network Environment
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Composed Services Under Investigation

• Overlay routing service connectivity and
  reachability (BGP Sharad, Lakshmi, Morley)
• Multicast service distribution tree formation
  across administrative domains (Mukund)
• Soft QoS Service performance constrained
  connectivity/latency and bandwidth guarantees
  (Clearinghouse Chen-nee, Lakshmi)
• Performance monitoring service distance/latency
  mapping, load collection/balancing across service
  instances (Yan)
• Content distribution services cache/storage
  resources, distribution/transport resources (Yan,
  Morley)

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Composed Services Under Investigation

• Infrastructure Services
• Highly available/fast fall-over services in
  wide-area (Bhaskar)Fall-back path bandwidth
  provisioning (Weidong)
• Service instance selection, load-balanced
  resource sharing
• Resource allocation/auctions and class-of-service
  pricing for bandwidth, processing, storage
  (Weidong Matt)
• Mobility and cooperation across access
  networks/device ensembles (Machi)
• Interdomain Authentication Access Control
  (Suzuki)

• Applications
• Content transformation/format translators
  Universal In-Box (Bhaskar)
• H.323 Gateway selection under load performance
  constraints (Matt)
• VoIP and bandwidth congestion pricing (Jimmy)
• Smart Spaces/PAN?

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SAHARA Architecture

• Network Environment
• Explicitly distinguish between multiple Access
  Networks and Core Networks
• Gateway Provider (GP)
• Points of Presence between different kinds of
  networks
• Path Provider (PP)
• Autonomous systems (AS) determine service domains
  for purposes of reachability
• Peering between administrative domains managed
  via BGP
• Point-to-point (and multipoint) latency,
  availability SLAs within a single administrative
  domain
• Datacenter Provider (DCP)
• Distributed computing resources (processing,
  storage) embedded within network topology
• Load/latency/availability SLAs within single
  datacenter location

Service
Generic Mgmt Control
Applications
Objects
Sessions
Trans- port
Distributed ProcessingEnvironment
Performance Verification
SLAs
Network Environment
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SAHARA Architecture

• Distributed ProcessingService Placement
• Place objects (operators data) at DCs,
  connected by paths
• Multiple object and path instances for load
  balancing, availability, scale
• Brokers
• Given performance other constraints
• Path brokering create overlay network among
  processing sites,link by link
• DC brokering given distribution of clients,
  select processing sites for operators
• Confederations
• Visibility of (alternative) paths, DCs among
  associated providers
• Peer-to-peer reassignment of objects to DCs and
  paths

Service
Generic Mgmt Control
Applications
Objects
Sessions
Trans- port
Distributed ProcessingEnvironment
Network Environment
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SAHARA Architecture

• Distributed ProcessingService Building
  Services
• Authorization, Authentication, Accounting
• Interworking services spanning administrative
  domains
• Service Selection and Naming Service
• Choosing a best service
• Finding nearest service instance
• Service Redirection Service
• Load balancing among service instances
• Selecting the best among services with common
  affinity
• Mobility support
• Resource Allocation Service
• Auction-based allocation
• Performance Measurement Service
• Network distance measurements
• Latency measurements for operator invocation over
  network

Service
Generic Mgmt Control
Applications
Objects
Sessions
Trans- port
Distributed ProcessingEnvironment
Network Environment
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SAHARA Architecture

• Applications
• Unified messaging services (Universal In-box)
• Content xform proxies
• Latency, availability, scalability
• Content-distribution services
• Cache placement replenishment algorithms
• Adaptive to client community evolution
• IP Telephony
• H.323 gateway selection/load balancing
• Balance between packet (IP) and circuit-switched
  (PSTN) path
• Device Ensembles/Virtual Devices
• Inter-network stream synchronization
• Virtual device proxy placement
• Virtual Home Environment

Service
Generic Mgmt Control
Applications
Objects
Sessions
Trans- port
Distributed ProcessingEnvironment
Network Environment
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SAHARA and TINA

• Key Differences
• Extreme heterogeneity of spanned networks and
  resources
• Greater awareness and management of underlying
  network topology/administrative scopes and affect
  on services
• Focus on
• Cooperative vs. competitive service composition
• Resource management via placement, allocation,
  redirection to services and resources
• Borrow good parts of TINA
• Applications/Distributed Processing/Network
  Environment
• Business models/Information Model/Computation
  Model
• Understand why TINA failed
• Avoid full-blown complexity of TINA

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Example Content Distribution

• Application Content Delivery
• Clients Subscribers, Publishers
• Services
• Distribution network
• Content caches (service instances)
• Place caches at selected DCs (service placement)
• Redirect client to best cache instance (service
  redirection)
• Based on proximity, load, content
• Service Composition
• Broker multi-point distribution paths between
  publishers and caches
• Add/delete cache instances as client community
  grows/shrinks
• Brokering at content level among competing CDNs

Service
Generic Mgmt Control
Applications
Objects
Sessions
Trans- port
Distributed ProcessingEnvironment
Network Environment
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SAHARA Architectural Model
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SAHARA Architectural Model
Service Path Creation
Service Selection Service Placement
Service Location Perf Measurement
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SAHARA Architectural Model
Load Balancing
Service Selection Service Placement
Service Redirection Perf Measurement
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SAHARA Architectural Model
Service Brokering
Path Determination
Perf Measurement Verification
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SAHARA Architectural Model
Service Confederation
Service Discovery SLA Negotiation
Perf Measurement SLA Verification
Authentication Authorization Interworking Mobili
ty Interworking
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SAHARA Architectural Model
High Availability Services
Service Failure Detection
Service Recovery Path re-composition
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SAHARA Architectural Model
High Availability Services
Service Location
Path Orthogonality Determination
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SAHARA Architectural Model
Universal In-Box
Translator Provisioning and Placement
Path Determination
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SAHARA Architectural Model
Content Distribution
Cache Provisioning and Placement
Distribution Tree Formation
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SAHARA Architectural Model
Voice over IP
Gateway Provisioning and Placement
Packet-to-CircuitTermination Selection
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Summary and Status

• Evolve (mobile) Internet architecture to better
  support multiple service provider model
• Dynamic environment, location-based implies
  larger numbers of service providers service
  instances
• Refine and build SAHARA Architecture
• Specification driven by selected applications and
  underlying wide-area services
• Composition across confederated vs. independent
  service providers peer-to-peer vs. brokering

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Discussion