ITU-T definition: NGN is a packet based network able to provide services (incl. telecom. Services) and able to make use of multiple broadband, QoS-enabled transport technologies and in which service-related functions are independent from underlaying transport-related technologies. It offers unrestricted access by users to different service providers and generalized mobility. NGN can be defined by following main features: - Consolidation of transport networks into one core transport network (often based on IP and Ethernet) => migration from PSTN to VoIP and from legacy services such as X.25, Frame Relay to IP VPN In wired access NGN implies the migration from legacy voice + xDSL in the Local Exchanges to a converged setup in which DSLAMs integrate voice ports or VoIP allowing to remove the voice switching infrastructure from the exchange. In cable access, NGN convergence implies migration of constant bit rate voice to CableLabs PacketCable standards that provide VoIP and SIP services over DOCSIS. NGN are based on IP and MPLS (Multiprotocol Label Switching) and at application level on SIP which took over the ITU-T H.323. H.323 originally popular in the “local loop” decreased in popularity due to its poor traversal of NAT and firewalls. More recently H.323 has been improved in this sense but as SIP has been selected as signaling protocol for IMS, it is not sure H.323 would come back again as an option. The NGN use Softswitches to control VoIP calls. A softswitch creates an interface to existing PSTN through SG (Signalling Gateways) and MG (Media Gateways) HSPA = HSDPA, HSUPA, HSPA+ (Evolved), HSOPA or OFDMA MBWA (Mobile Broadband Wireless Access) = 802.20 WiMAX = 802.16-2004(d)/-2005(e); Fixed WiMAX = 802.16-2004(d); Mobile WiMAX = 802.16e WiFi = 802.11a/g
Fixed applications Person-to-Content: Games, Internet, News, Corporate access Person-to-Person: Games, E-mails, Voice calls, Video calls The NGN architecture provides the foundation for the integration of Person-to-Content and Person-to-Person communication paradigms. Thus, irrespective of the fact that the end point is a user controlled device or an AS hosting content, same packet-based access and transport network, control plane and service layer are used. The asynchronous delivery of content to an user is similar to requesting a person-to-person session for that user. The session setup, control, content sharing management, instantiation of other interactive services while accessing the content can/need to be handled in a unified way. Besides the efficient network implementation, the real-time aspect matters also to very large extent. The NGN architecture and implicitly IMS provide a framework for both Person-to-Person and Person-to-Content application. Same infrastructure is used to deploy new innovative services at a fast pace. Community services can be much faster developed and deployed.
IMS is a standard-based way of creating a Next Generation Network. IMS specifications also define ways of creating and delivering applications on that network, together with managing related functions like QoS and charging. Why operators are interested in IMS: Bottom-up reason: operators decided to move towards NGN and IP and IMS is an “off the shelf” and well-defined way of achieving this. This reason weighs over the second one as low-level infrastructure stories have much easier ROI in terms of opex/capex than predicting future growth of services. Top down reason: application-centric view where IMS is a solution to the improvement of flexibility, costs and deployment speed of providing services to subscribers. IMS follows the success story of the Internet and enterprise IT which have shown the benefits of having shared functions in the network and shared capabilities on the device. Also the “open” and “platform-based” nature of the Internet means that a vast array of developers can write applications. IMS attractions go beyond unifying different “downloadables” into one architecture as they provide real-time/interactive features and of course is based on IP. IMS is based on SIP and it seems that both have gained a lot from this “joint-venture” The opinion is that SIP may not have gained so much popularity and credibility should have been not adopted by IMS. Opinions on IMS: IMS is complex and there will be various “shades of grey” ranging from best-effort Internet architecture, through the more pragmatic IMS-like-NGN-embracing approach. There will be some decent “top-down” applications that will share various common functions IMS provides support for emergency services, lawful intercept and priority services The problems start when one considers GSMA solution with purely operator-controlled IMS domain. Internet model is on the other hand best effort, completely open to any appl. provider plus the promise the users or advertisers will pay for “premium, even better stuff”
Phase 1: The P- removes any potential route and replaces it with a route to S-CSCF. This route is defined during IMS registration and may traverse an I-CSCF (topology hiding) Phase 2: The S-CSCF applies the service profile for originating IMPU. This profile consists of a set of IFCs which give a list of services to apply by originating network. It is possible that one of invoked AS’ terminates the SIP request (SIP UA). This happens when the request was addressed to a PSI, or when the request was sent to itself (ex. PUBLISH for presence event package is addressed to user’s own IMPU) Phase 3: Routing to terminating network according to the RequestURI. In case the Request-URI is a TelURI, the S-CSCF will route to PSTN if the TEL URI is not resolved to a SIP URI by the DNS ENUM. Through the DNS, the S- also determines if the request is for a non-IMS network (Internet) Phase 4: Routing the request to S-CSCF in terminating network. It is necessary to reach B S-CSCF as some of B party’s services may have to be invoked when B is not available (e.g. presence) Phase 5: The terminating S-CSCF applies terminating side service profile associated with the IMPU or PSI corresponding to the Request URI. Phase 6: Delivery to terminating party Note: IMS routes based on UserIDs and ServiceIDs whereas SOA routes based on ServiceIDs only.
RDF is a framework for the creation of statements (triplets) which enables to represent information about the resources as a graph => Semantic Web is know as the “Giant Global Graph” RDFS provides a basic vocabulary for RDF. It allows the definition of hierarchies of classes and properties RIF and SWRL brings support of rules. It adds semantic description to relations which could not be described in OWL. OWL extends RDFS by adding more advanced constructs to describe semantics of RDF statements. It allows stating additional constrains (cardinality, restrictions of values, properties such as transitivity). It brings reasoning power to the semantic web. SPARQL is a RDF query language
Message Oriented Middleware (MOM) is a client/server architecture which isolates the application developer from underlying OS details by making use of APIs which extend across multiple platforms and networks. Java Message Service (JMS) is an API implemented by most MOM vendors. SOC inherently promotes SOA, though it is not the same as SOA. Due to language and platform independent Web Service standards, SOC/SOP embraces all existing programming paradigms, languages and platforms. In SOP, the design of the programs pivots around the semantics of service calls, logical routing and data flow description across well-defined service interfaces. A service can be an externalized component from another system accessed either through using Web Service standards or any proprietary API through an in-memory plug-in mechanism. Composite Service A composite service implementation in SOC is the semantic definition of a service module based on SOP techniques and concepts. A Composite service may have a recursive definition meaning that any service inside (“inner service”) may be another atomic or composite service. An inner service may be a recursive reference to the same containing composite service. Atomic Service An Atomic service is an in-memory extension of the SOP runtime environment through a Service Native Interface (SNI). Service Discovery Web 1.0/2.0, generation of Web services is manual in the sense that a registry (UDDI) is searched by developers of client systems, rather than middle agents / user during execution. In contrast, semantic matchmakers use semantic relations to find services described using Semantic Web languages (OWL, WSML, WSMO)
Web 2.0 is a term that describes a trend in World Wide Web that fosters creativity, information sharing and most notably collaboration among the users . Main Web 2.0 services are web-based communities and hosted services such as: social-networking sites, wikis, blogs, folksonomies . Although it suggests a new version of the Web, it does not refer to an update to any technical specifications. It is rather a move towards the Internet as a distributed platform. Web 2.0 can also be characterized as a transition from isolated information silos to interlinked computing platforms as data is aggregated from various servers in the network. Web 2.0 also addresses the social element where users can generate and distribute content. Architecture components: Server software, Content syndication, Messaging protocols, Standards-oriented browsers with plugins and extensions, and Client applications. Web 2.0 site features: CSS, Folksonomies (social tagging, indexing), Semantic microformats (sometimes), REST and/or XML and/or JSON based APIs, Rich Internet Application typically based on AJAX, XHTML/HTML semantically valid, Syndication/aggregation/notification of data with RSS or Atom feeds, Mashups merging content from various sources, Weblog for publishing sites, Wiki or Forum for user-generated content, Internet privacy to allow user manage their own privacy Web 2.0 Criticism Web 2.0 is not something new. Protocols like AJAX do not replace HTTP, but add an abstraction layer on top of it. Many of the ideas claimed in Web 2.0 have already been featured in networked systems implementations well before 2.0 emerged (ex. Amazon allowed a form of self-publishing since 1995). Tim Berners-Lee, the father of the Semantic Web and founder of W3C, characterized Web 2.0 as: “if Web 2.0 for you is blogs and wikis, then that is people to people (communication). But that was what the Web was supposed to be all along” . Other criticism has included the term “a second bubble” in reference to Dot-com bubble 1995-2001. The analogy is based on the fact that too many companies attempt to develop the same product with lack of proven business model. In the end, the winners will be only those who own data mashed-up in successful applications. Software development will not pay back.
Web Service Choreography (WSCI) = W3C specification defining a XML business process modeling language which describes the interaction protocols between Web Service participants that. Services act as peers and interactions may be long-lived and stateful. WS-BPEL (Web Services Business Process Execution Language) or simply BPEL = Language for describing business process behavior based on Web Services. BPEL is an Orchestration language, not a Choreography Language. BPEL is based on messages and provides structured-programming constructs and encapsulation of logic with variables, handlers etc. All BPEL implementations must support XPath 1.0 (language for the selection of nodes from a XML document) as default language. Note : Apple iPhone has 620 Mhz CPU and 128 MB RAM.
Neurocommons = RDF DB developed by Science Commons compiled from major life sciences databases with focus on neurology. It is accessible with SPARQL query language. OWL-S = An ontology built using Ontology Web Language (OWL) for the Semantic Web. It has three parts: Service profile = describes what the service does (this info is primarily for human reading) Process model = describes how to interact with the service (i.e. inputs, outputs, pre-conditions etc.) Service Grounding = details on interaction (communication protocols, message formats, ports) SWSF = Semantic Web Services Framework contains an ontology (SWSO) and a language (SWSL). The SWSO is an extension of OWL-S. SWSF does not clearly define how the elements of the framework work together. SWSF contains language description for both static and dynamic behavior. IRS-III = Internet Reasoning Service is a broker handling mediation between clients and deployed services. Does not define an actual FW. Instead it reuses WSMO. It consists of an IRS Server, IRS Publisher and IRS Client. WSMO = Web Service Modeling Ontology is formalized using Web Service Modeling Language (WDML). It is based on: Capabilities - what the service can do, preconditions/postconditions; Interfaces - how to access the service, choreography/orchestration; Goals ; Mediation – data, protocol, process mediation. WSML allows description of both the static and dynamic behavior. Services described in WSMO execute in WSMX environment. WSMX can be seen as reference implementation of WSMO and a SOA using dynamic binding. The Semantic Web allows automatic : Service Discovery Service Execution = i f executing the service is a multi-step procedure, the software needs to know how to interact with the service to complete the necessary sequence. A Semantic Web service provides a descriptive list of what an agent needs to be able to do to execute and fulfill the service. Service Composition = how to select and combine a number of Web services to complete a certain objective. Service Monitoring = Agents need to be able to verify and monitor the service properties during run-time.
Communication Handler = Protocol handler and parser which terminates all communication session from external nodes. Service Mediation = Handles data, protocol and business process mediation (adaptation to a specific format/syntax) using pre-defined mappings. Data refers to ontologies, while processes refer to rules. Mediation can be used in various execution stages: discovery, composition, invocation. Semantic/Ontology Reasoning = The reasoning engine (ex. IRIS, KAON2, MINS, PELLET) evaluates queries over a knowledge database. For each query, the engine returns the variable bindings (set of all tuples that can be found or inferred from the knowledge database that satisfy the query) Web Service Discovery = Finds the services which fulfill the formulated goal. Ranks services discovered based on a given criteria (ex. QoS) and interacts with the Matchmaker (Broker) to select one of them. Composition Engine = Selects the composition paradigm, i.e. Orchestration or Choreography. Choreography is a stateful, public process. It selects the service to invoke by analyzing state transitions and requester’s goal in relation to service provider’s description. Service instantiation steps : Late binding: WS Discovery: a WS which can satisfy the goal is found in the WS repository Service Selection: discovered services are ranked based on criteria like QoS Execution: Mediation: handles data/protocol/process adaptations between requester and provider. Process mediation refers to actually performing the composition (orchestration or choreography) Service invocation and grounding: data is transformed from ontology format to the XML message format.
Xplan Composition Preliminary processing = preparing input data, creation of type-hierarchies, filtering relevant operator instances. Connectivity graph = generation of a dependency graph Goal determination = setting-up of a (reachable) goal Planning Graph Generation = Upper modules are part of the re-planning sub-system. This engine generates the relaxed planning graph where operators have no delete lists and extracts relevant operators. Enforced Hill Climbing Engine = Is a Hill-Climbing procedure (which is a of Fast Forward Chaining heuristics) that, in each intermediate state, uses breadth first search to find a strictly better, possibly indirect, successor. Relaxed plans can be used to prune (clean-up) the search space. The main drawback of EHC is that the search heuristics sometimes can not escape from a plateau in one step therefore exhaustive search periods is then required bridged by relatively quick periods of heuristic descent. PDDXML = Planning Domain Definition XML
Advanced Paradigms for Building Convergent Next Generation Services. Service Composition and Service Brokerage in Multimedia Architectures Dr. Sorin Georgescu [email_address]
Converged business models Increased margins, Avoidance of twin pitfalls risk
The Evolution to Multimedia Applications A Mobile View Non-Interactive Multimedia Image SMS MMS Presence Active phonebook Push-To-Talk Text Voice Voice P2P Calls Video Person-to-Person dominates traffic growth Movies Photos Internet Text/Pictures SMS/MMS HTTP Streaming Download Video Music Ring tone Person-to-Content known usability patterns Interactive Multimedia Multimedia Content Social Networking
IMS – 3GPP Architecture for Convergent Next Generation Services
IMS is an open IP-based architecture using the Client-Server Network Computing model.
3GPP originally specified IMS to enable real-time multimedia services over the IP bearer, in GSM and W-CDMA networks.
Later, 3GPP2 specified the MMD architecture for CDMA2000 networks based on IMS. 3GPP2 requirements are part of Common IMS in IMS release 8.
The xDSL access, specified by TISPAN, is integrated into IMS.
The cable access, specified by CableLabs in PacketCable 2.0, is part of IMS release 8.
Interworking with WLAN was specified in IMS release 6, while the mobility with WiMAX has been addressed in EPC specifications.
If IMS is not used:
Multimedia communication at best effort
Service roaming can be difficult to implement
Provisioning and charging are service specific
Compliance with LI requirements can be an issue
IMS Service Routing – the IFCs P-CSCF Visited A P-CSCF Visited B S-CSCF IMS AS HSS S-CSCF IMS AS HSS I-CSCF 1 2 3 4 Home A Home B 5 6 7 8 9 10 11
In comparison to IETF SIP Routing where the originator of SIP request may specify a preferred path in the Route header, in IMS the P-CSCF removes this path and ensures that IMS SIP Routing is followed.
SIP requests in IMS architecture are always routed to the Home S-CSCF, in both the originating and terminating network.
The S-CSCF uses subscriber’s Service Profile (downloaded during registration), to link-in the SIP AS’ which will process the SIP request.
The Initial Filter Criteria (IFC) within the Subscriber Profile provide a simple service logic to decide which AS shall be linked-in. These rules are of static nature i.e. they do not change frequently.
IMS Service Routing = Service Profile based Routing
If during call handling procedure an AS retargets the SIP request by changing the Request URI, subsequent filter analysis in the S-CSCF is stopped and the S-CSCF forwards the request towards the new target without linking-in the other AS’ specified by IFC.
“ An Ontology is a formal, explicit specification of a shared conceptualization of a domain.”
Formal = unambiguous, machine understandable, described using a formal language
Explicit = precise, clarifying the subject
Conceptualization = abstract representation of the object of study
Ontologies consist of a set of axioms which place constrains on classes of individuals, and the types of relationships allowed between them.
Can be described in graphical form (ex. RDF, UML) or logical form (ex. Description Logic, Rules).
RDF/S = Resource Description Framework / Schema OWL = Ontology Web Language SWRL = Semantic Web Rule Language RIF = Rules Interchange Format Semantic Web Stack User Interface and Applications Trust Encryption Proof RIF/ SWRL OWL Logic RDFS SPARQL RDF XML URI Unicode
Enhancing the Business Model through Service Brokerage
Service Oriented Computing (SOC) Service composition types: Service Orchestration = centralized engine which coordinates composed services according to a set of rules (workflow specification) Service Choreography = multiple actors/agents participate at the implementation of service composition (orchestration between every pair of choreographers)
In SOC, applications are statically/dynamically composed using services deployed in the network. The collaboration model can be t ransactional (synchronous), or workflow-based (asynchronous)
SOA is one possible realization framework of SOC. The communication paradigm typically used in SOA is Web Services
Web Services are:
Published (WSDL, OWL, SWSF)
Discovered (UDDI, WSMO)
Distributed Computing Evolution Message Driven (MOM) Components (Corba, EJB) Client/Server Service Oriented (SOA, Web 3.0)
Service Oriented Computing (cont.) Static Service Composition Developer Studio End User Studio Service Creation Environment Publish UDDI Composition Engine Discover User / Service Profile User context BPEL Rules Ambient context Service Discovery and Publication Temporal context Broker Context
Compared to BPEL/WSCI developer-centric composition, Web 2.0 uses ad-hoc composition . The user builds the composite service “on-the-fly” from data retrieved from the network. Mobile devices (Smartphones) now have 128MB of RAM and 620 Mhz CPU, so Web 2.0 clients can now be mobile.
Web 2.0 application design is performed by the end user who in essence, has low programming skills. The service composition is defined through interaction with a GUI.
Client controlled composition
Development: client components use APIs to access server data
Execution: components run on the client and pre-fetch data from the server
Server controlled composition (early stage)
Development: the server uses public APIs to link services into new services
Execution: the client invokes the server which acts as an orchestrator
Photo Storage Data Base Node Service Application Logic Page Logic API Templates Endpoints Email Flickr.com 3PP Appl. Flickr Appl Flicker Architecture
Enhancing the Business Model through Service Brokerage
The Semantic Web Tim Berners-Lee, 2001: “ The Semantic Web looks at applications that enable transformations, by being able to take large amounts of data and be able to run models on the fly - whether these are financial models for oil futures, discovering the synergies between biology and chemistry researchers in the Life Sciences, or getting the best price and service on a new pair of hiking boots.”
Information on the Web is machine understandable => automatic service discovery, invocation and composition.
Modeled as a graph where nodes have semantic descriptions. In Web 1.0 and 2.0 node descriptions are only syntactic.
Uses ontologies to represent elements of a domain and their relationships (OWL-S, SWSF, IRS-III, WSMO)
Non-semantic web tag: <item>cat</item> Semantic web tag: <item rdf:about=“http://dbpedia.org/resource/cat”>cat</item> SWS Service Profile Semantic Modeling using OWL-S Service Grounding Service Model presented by implements interacts using SWS = Semantic Web Service
Action Based : the Reasoner uses the semantic description of discovered services to match requester goal at each composition step (run-time). Execution takes place directly through the grounding of the services.
AI Planning : a task list is generated to achieve the composition objectives i.e. service selection and flow management. Compensation in case of failure and replanning is a challenge. Examples of AI Planning: Conditional Planning, Conformant Planning, Hierarchical Task Planning (HTP)
Hybrid (Xplan) : Combines guided local search with graph planning and a light form of HTP to produce a plan sequence of actions.
There is not yet a unifying framework to allow interoperability between intelligent agents / reasoning engines. Y Z X Z X Y Planning - Set of actions - Pos./neg. effects - Initial state description - User’s goal Sequence PDDXML Parser Topology Handler Connectivity Graph Goal Determination Xplan-based Composition Enforced Hill Climbing Engine PDDXML plan description Planning Graph Generation PDDXML problem, domain description
Users are interested to customize service interaction model and run-time features based on context conditions (Ambient Intelligence, Location, Privacy Preferences etc.)
Control of the payment model. Users who do not want adds and are rather looking into QoS and Security/Privacy, need a Service Broker function in the network which can negotiate the service characteristics with multiple service providers based on user profile.
Google business model: Users accept advertising and profiling in return to free services. AsSense, AdWorks - advertisers/publishers or youTube - content providers/users, perform brokerage at business level.
Service Broker functions:
Ranks services offered by the Service Providers based on service characteristics. It may do this autonomously (rules based negotiation), or by interacting with the user
Matches the service interaction model with context conditions
Performs identity and trust brokering
Performs payment brokering
Handles synchronization between fine-grained services
Service Consumer Service Description Service Provider invoke ( ) bindTo ( ) Service Broker find ( ) negotiate ( ) use offer described in contains description User / Service Profile User context Ambient context Temporal context Broker Context decisions
The roles in Payment Model are similar to those in Credit Card industry:
Merchant = Content Provider who publishes, supplies and sells content.
Issuer = Mobile Operator. The Operator uses its existing billing relationship with the consumer to charge for content.
IMS services standardized so far (MMtel, PoC, Image/Video Share) have been deployed in the operator domain as their target are the telecom communities (mass deployments).
Separate from these basic services, it is expected that many new community specific services (niche services) will be provided in the near future by Service Providers. These services use open communication protocols (instead of SIP) and do not handle charging of the user directly. Instead, they use their business and trust relationship with the operator, to delegate payment service.
The Payment Brokerage function facilitates the establishment of the business relation between 3rd Party Content/Service Providers and mobile operators.
Recent deployments of Multimedia and VoIP services in the Telcom and the Internet domain, have determined a blurring of roles in the value chain while at the same time enabling new business models.
Next Generation Services Convergence requires:
Implementation of converged devices (multi-access devices)
Support of a multi-access edge network
Unified roaming and session management framework
Development of service enablers
Interoperability between the native Service Platform (SP) and external Service Overlay Networks
The SP Interoperability Middleware has to provide support for:
Service Composition and Brokerage
Service Platform features like Multimodal Interaction, Interaction Management based on Ambient Intelligence, Content Management, Brokerage and Management of Semantic Information are desirable due to their significant impact on service usability.