(531784349) Chapter 6 Pages From IP Multimedia Subsystem (IMS) Handbook 2009

6

Next-Generation Grid Support over the SIP/IMS Platform

Vicente Olmedo, Antonio Cuevas, Victor Villagr, and Jos I. Moreno

CONTENTSIntroduction.......................................................................................................... 134Advantages.of.GridIMS.Interaction....................................................... 135Architecting.a.New.Grid.Environment:.Commercially.Oriented.with.Dynamic.and.Mobile.Services................................................ 136Base.Virtual.Organization......................................................................... 137Operational.Virtual.Organization............................................................ 138Service.Provider.......................................................................................... 140Network.Provider....................................................................................... 140Integrating.IMSs.SIP.Infrastructure.and.Grids:.Mobile.and.Dynamic.Grid.Environment............................................................ 141Involved.Protocols:.SIP.and.SOAP........................................................... 141Integrating.SIP.and.SOAP......................................................................... 142SIP.Support.for.SOAP-Based.Grid.Services............................................ 144Initialization.................................................................................... 144Setting.Up.Sessions.Involving.Services.Running.in.MTs......... 144Disconnection.and.Reconnection.of.Terminals.and.Their.Services;.Mobility............................................................. 147Accidental.Disconnection.............................................................. 149Changes.in.Services.in.the.Terminals.While.the.Session.Is.Running............................................................................. 149Session.Teardown........................................................................... 149Integrating.Grid.Services.and.SIP-Controlled.Audio/Video.Calls..... 149Integrating.Grid.with.the.Network.Operator.Infrastructure.Reusing.IMS-Defined.Interfaces...................................................... 151PDF/PCRF.Interface.to.Grid.Service.Provider....................................... 152Interfaces.to.the.HSS.and.CDF.for.User.Control.................................... 154Conclusion............................................................................................................. 155References............................................................................................................. 155

1

Introduction

In.the.near.future,.network.operators.may.lose.their.central.position.in.the. telecommunications.business.value.chain.and.become.mere.bit.pipes..That. is.why.service.platforms.controlled.by.the.operators,.such.as.i-mode.or.the. IP.multimedia.subsystem.(IMS),.are.becoming.so.important..IMS.is.a.well- designed.service.platform,.using.open.and.standardized.Internet.protocols. and.respecting.the.Internet.paradigm.of.data.transport.and.application.sepa- ration,.yet.still.building.links.between.these.two.layers.[1].Service.platforms.must.entice.users.to.employ.them,.offering.a.rich.service. environment.. IMS. is. a. promising. service. platform,. but. it. targets. only. standardized.initiation.session.(SIP).proxiable.applicationsthat.is,.applications. that.use.the.SIP.protocol.and.SIP.proxies.to.help.control.the.sessions.between. the.participants..An.example.of.these.applications.is.audio.and.video.confer- encing..These.peer-to-peer.applications.allow.users,.among.others,.to.make. the.traditional.phone.calls.that.are,.still.today,.the.network.operators.main. business..However,.many.of.the.applications.with.great.user.acceptance.do. not.use.the.SIP.protocol.and.thus.are.out.of.the.IMS.scope..Some.examples. are. ring. tone. downloads,. online. games,. and. content. sharing. applications.. These. applications. have. a. great. commercial. acceptance. and. represent. an. ever-increasing.source.of.revenues.for.network.providers..Efforts.are.being. made.to.broaden.the.panoply.of.services.that.can.fit.under.the.IMS.control. framework.. The. Open. Service. Architecture. (OSA)/Parlay. consortium. [2]. developed. and. develops. means. for. service. providers. to. interact. with. network.operators;.integrating.OSA/Parlay.with.IMS.is.one.of.the.main.efforts. made. to. broaden. the. set. of. services. available. under. the. IMS. platform.. The. Open. Mobile. Alliance. (OMA). [3]. is. the. leading. actor. in. enriching. the. services.offered.over.the.IMS.platform.In. parallel. to. IMS,. the. traditional. distributed. computing. community. (finally. evolved. toward. the. Grid/Web. services. community). came. up. with. solutions. and. concepts. that. could. also. be. used. for. bundling. services. and,. ultimately,.building.service.platforms.and.rich.service.environments..A.very. important.notion.within.the.Grid.framework.is.the.notion.of.a.Virtual.Orga- nization.(VO)..A.VO.is.a.temporary.or.permanent.coalition.of.geographically. dispersed.individuals,.groups,.organizational.units,.or.entire.organizations. that. pool. resources,. capabilities,. and. information. to. contribute. to. the. VO. according. to. the. established. contracts.. These. contracts. are. typically. driven. by.one.or.more.business.processes..VOs.can.provide.services.and.thus.participate.as.single.entities.in.the.formation.of.additional.VOs..This.enables.the. creation.of.recursive.structures.with.multiple.layers.of.virtual.value-add- ing.service.providers.

Next-Generation Grid Support over the SIP/IMS Platform 13 Many. Grid. environments. are. created. using. the. Web. Services. Resource. Framework. (WSRF). [4]. level. and. the. Open. Grid. Services. Architecture. (OGSA). [5]. services. layers.. All. Grid. resources,. both. logical. and. physical,. are. modeled. as. services. on. the. basis. of. Web. service. implementations.. For.

the. purposes. of. resource. modeling. in. the. Grid,. the. Web. service. interfaces. must.frequently.allow.for.the.manipulation.of.statethat.is,.data.values.that. persist.across.and.evolve.as.a.result.of.Web.service.interactions..One.of.the. main.goals.of.the.WSRF.is.to.achieve.this.state.control..The.WSRF.defines.a. family.of.specifications.for.accessing.stateful.resources.using.Web.services.. Note.that.communication.services.(e.g.,.voice.calls).are.also.described.using. this.framework..The.Web.services.layer,.together.with.the.WSRF,.provides.a. base. infrastructure. for. the. OGSA. services. layer. providing. the. overall. Grid. management.functionality..The.basic.motivation.is.to.provide.OGSA-specific. services.implemented.through.the.WSRF.

Advantages of GridIMS Interaction

Grids. offer. a. service. composition. and. orchestration. that. is. not. as. central- ized.as.in.the.IMS,.and.they.support.a.more.heterogeneous.range.of.devices. and.services.than.the.IMS..In.Grid.environments.we.could.even.consider.as. services.the.capabilities.of.a.user.(such.as.a.medical.first-aid.worker).logged. into.his.or.her.device..However,.we.must.bear.in.mind.that.these.types.of.services.are.very.dynamic.because.users.(with.their.devices).may.move,.change. the.device.they.employ,.or.simply.disappear.(shut.down.the.device.or.lose. connectivity)..This.kind.of.dynamicity.is.better.supported.in.IMS-.and.SIP- based. environments. than. in. Grid. scenarios.. Granting. Grids. mobility. and. dynamicity.[6].is.one.of.the.rationales.for.integrating.Grids.and.IMS.IMS.is.a.service.platform.very.targeted.to.the.commercial.world,.whereas. Grids.are. weaker. in.this.point..Integrating.Grids.and.IMS.will.provide.the. necessary.mechanisms.to.bias.the.Grid.world.toward.a.commercial.environment,.if.this.is.needed.IMS. builds. links. between. the. application. layer. and. the. transport. level. to. achieve,. among. other. things,. an. integrated. quality. of. service. (QoS). coordinating. these. two. layers.. This. is. especially. relevant. for. IMS. core. applications. like. user-to-user. audio/video. communications.. Grid. applications. may. not. have. such. stringent. QoS. requests;. thus,. the. Grid. world. does. not.care.much.about.coordinating.the.QoS.offered.by.the.network.operator. for.its.data.transport.service.and.the.QoS.at.application.layer..Thus,.integrating. IMS. and. Grids. will. span. the. IMS-rich. QoS. control. mechanisms. to. the. Grid.In.the.approach.described.in.this.chapter,.thanks.to.their.interaction.within. the.IMS.service.platform,.Grid.applications.(using.the.Web.services.framework).will.be.able.to:

establish. a. Grid. session. with. a. mobile/ubiquitous. service. without. prior.knowledge.of.its.current.location; use.the.SIP.mechanisms.to.manage.sessions,.like.transfer.a.session,. or.perform.third-party.Grid.session.control..This.includes.integrating.non-grid.applications.like.SIP.controlled.voice.calls;

use.the.presence.and.context.management.mechanisms.established. by. the. SIP. for. Instant. Messaging. and. Presence. Leveraging. Exten- sions.(SIP.SIMPLE).infrastructure;.and use. IMS. mechanisms. to. bill. for. the. service. and. authenticate. and. authorize.users.

Figure.6.1.depicts.the.general.architecture.of.a.service.environment.com- posed. of. the. IMS. service. platform. and. Grid. services.. Further. sections. will. detail.how.this.service.environment.is.achieved.By. integrating. Grids. and. IMS,. the. IMS. service. platform. is. enriched. to. build. a. more. complete. and. attractive. service. environment. that. will. attract. users..Integration.of.Grids.(and.more.specifically,.Web.services).and.IMS.still. falls. into. the. research. field.. Solutions. have. been. presented,. such. as. those. in.reference.7..In.this.chapter.we.describe.the.solution.provided.within.the. Akogrimo.project.[8]..Following.sections.explain.how.this.enhanced.service. platform.is.achieved.in.the.Akogrimo.project.

Architecting a New Grid Environment: CommerciallyOriented with Dynamic and Mobile Services

Grids. are. a. collection. of. heterogeneous. devices. with. different. capabilities. and. services. offered;. they. are. interconnected. and. work. together. toward. a.

ContentProvider

SIP SessionControl

User Control and Billing

TravelAgency

Online German-Spanish Translation

Network Provider

ServiceDiscovery

First-aidCapabilities

FIGure 6.1An. enhanced. service. environment:. control. elements. from. the. IMS. service. platform. and. Grid.services.

common.goal..This.set.of.devices.is.often.called.a.Virtual.Organization..Many. grid.environments.are.created.using.the.WSRF.level.and.the.OGSA.service. layer..All.Grid.resources,.both.logical.and.physical,.are.modeled.as.services. on.the.basis.of.Web.service.implementations..Web.services.are.stateful,.and. one.of.the.WSRFs.goals.is.to.take.this.into.account..Communication.services. (e.g.,.voice.calls).are.also.described.using.this.framework.Grids. are. often. decentralized. and. they. build. up. themselves. and. offer. services. in. a. rather. dynamic. way.. However,. normally,. they. are. not. commercially.oriented;.they.are.not.user.centric.and.do.not.consider.that.users. (logged.in.to.their.devices).may.offer.services,.like.medical.first.aid..To.integrate. Grid. organizations. in. the. telecommunication. business. and. support. services.offered.by.users,.the.following.building.blocks.have.been.identified. (Figure.6.2).

Base Virtual Organization

One. of. the. main. building. blocks. in. Grid. architectures. is. the. Base. Virtual. Organization. (BVO).. Essentially,. a. BVO. is. a. suite. of. Service. Providers. (SPs).

Base VO

Customer Domain

VO Management

Discovery

Identity

Context Manager

Accounting & Charging

OpVO

Identity

User User

Accounting & Charging

OpVOManagement Composition

Identity

Network Provider

NetworkManagement

Services

Service Provider

ExecutionManagement

Services

Discovery

Identity Accounting & Charging

Discovery DataManagement

Identity Accounting & Charging

FIGure 6.2Grid.building.blocks.making.possible.its.integration.within.IMS.

linked.by.a.contract;.in.order.to.provide.specific.services,.they.work.together. under. the. terms. of. this. contract. stated. in. the. Service. Level. Agreements. (SLAs)..This.contract.is.signed.and.is.settled.on.a.quite.static.basis..For.the. Grid. environment. to. meet. the. semiwalled. garden. business. model. (fol- lowed. by. the. IMS),. the. SPs. forming. the. BVO. must. also. have. a. contractual. relationship.with.the.Network.Provider.(NP)..In.the.semiwalled.garden.business.model.this.contract.states,.among.other.things,.that.the.main.part.of.the. customer.relationship.is.handled.by.the.NP.The.contracts.linking.the.SPs.between.them.inside.the.BVO.and.to.the.NP. are.settled.in.a.static.way..However,.the.subset.of.the.BVOs.elements.work- ing. together. and. offering. a. (billable). service. to. the. customers. is. instantiated.dynamically,.forming.the.Operational.VO.(OpVO).that.we.will.study. later.Next. we. provide. the. details. of. the. relationships. established. between. the. BVO.and.the.other.building.blocks:

The.NP.supplies.the.network.infrastructure.to.access.the.BVO..The.BVO.leverages.on.the.trusted.NP.(which.is.a.member.of.the.BVO).to.authenticate.the.identity.of.the.incoming.requests.(essentially.com-ing.from.customers.or.from.SPs.forming.the.BVO). The.customer.will.be.allowed.to.perform.two.main.actions.inside.a.BVO:.searching.for.services.and.creating.OpVOs.(detailed.next). The. SP. will. be. allowed. to. publish. its. services. inside. the. BVO,. and. their. use. will. be. acquired. by. the. customer. through. the. BVO. itself. (by.the.instantiation.of.OpVOs). The. OpVO. building. block. is. a. component. internal. to. the. BVO.. The.BVO. interacts. with. the. OpVO,. creating. it. and. configuring. a. dedi-cated.subdomain.for.its.execution.

Figure.6.3.depicts.the.concept.of.BVO.and.compares.it.to.Figure.6.4,.which. illustrates.the.concept.of.OpVO.that.we.explain.in.the.next.section.

Operational Virtual Organization

The. OpVO. is. a. building. block. that. assumes. an. important. role. at. execution. time.when.the.application.is.actually.delivered.to.the.customer..The.OpVO.is. the.run.time.environment.of.some.of.the.providers.offering.their.services. inside.the.BVO..In.any.case,.the.OpVO.lives.inside.a.BVO.and.several.OpVOs. can. be. instantiated. in. each. BVO.. The. SP. will. be. contacted. by. the. OpVO. in. order.to.negotiate.the.instantiation.of.the.services.needed.for.the.Grid.environment.execution..The.success.of.this.negotiation.will.lead.to.the.dynamic. establishment.of.a.contract..Because.this.process.is.done.within.a.BVO.that.

Grid SP

Grid SP

Grid SP

Grid SP

Grid SP

Base VO

Network Provider

FIGure 6.3A. BVO. and. its. contract. with. the. Network. Provider;. also,. Network. Provider. contracts. with. the. users.

Grid SP

Grid SP Grid SP

Base VO

Network Provider

Grid SP

Grid SP

FIGure 6.4Two.OpVOs.dynamically.instantiated.inside.a.BVO.

holds.a.static.contract.with.the.NP.(among.others),.the.NP.may.participate. in.the.control.of.the.services.delivered.over.an.OpVO.The.customer.will.be.allowed.to.perform.some.administrative.actions.on. the.OpVO.(e.g.,.subscription.of.new.users).because.he.or.she.is.the.owner.of.

the. OpVO.. Furthermore,. the. customer. (or. any. other. user. delegated. by. the. customer). can. use. (paying. for. it). the. applications. instantiated. through. an. OpVO.. Most. important,. users. logged. in. to. their. devices. can. offer. services. and. charge. for. them.. These. services. exist. in. a. very. dynamic. way. because. users.(with.their.devices).may.move,.change.the.device.they.employ,.switch. it.off,.etc.On.the.other.side,.services.by.providers.are.far.more.stable..The.existence.of. OpVOs.allows.integrating.these.two.types.of.service.provisioning.scenarios. Because.the.OpVO.is.an.instance.inside.the.BVO.and.the.BVO.has.relationships.with.the.NP.following.the.semiwalled.garden.business.model,.an.integrated. billing. (controlled. by. the. NP). is. possible,. despite. the. very. different.nature.of.services.(Grid.and.non-Grid).offered.in.the.OpVO.

Service Provider

Services. that. manage. and. supply. resources. and. enforce. policies. and. SLAs. reside. in. the. SP. domain.. The. service. offered. by. the. SP. will. interact. and. cooperate.within.the.OpVO,.contributing.to.the.global.Grid.service.delivery.. Thus,.SPs.must.expose.their.services.to.the.orchestration.carried.inside.the. OpVO.. This. includes. advertising. the. services. offered,. registering. them. in. the. appropriate. service. index. (this. server. will. be. a. SIP. registrar,. the. IMSs. S-CSCF,.as.we.will.detail.later)..This.service.index.can.also.be.queried.by.SPs. to.find.needed.services.Because.Grids.are.to.be.integrated.in.a.commercial.environment.(as.the. IMS. is),. a. function. that. supports. the. metering. of. the. resources. that. are. being. consumed. during. the. execution. of. a. service. is. located. in. every. SP. hosting. a. service. for. sale.. Emulating. the. IMS. behavior,. the. SP. will. send. accounting.data,.at.least,.to.some.specialized.nodes.in.the.NP,.aggregating. and. correlating. accounting. data. coming. from. different. sources.. All. services. located. in. the. SP. domain. are. accompanied. by. a. set. of. mechanisms. targeted.to.establishing.identity.and.negotiating.authentication..They.will. depend. on. the. authentication. services,. among. others,. offered. by. the. network. operator.. Note. that. services. offered. by. SPs. run. in. the. OpVOs. and. these.are.instances.of.the.BVO,.which.has.contracts.with.the.NP..These.contracts.allow.the.SPs.to.employ.the.accounting,.charging,.and.authentication. services.delivered.by.the.NP.

Network Provider

Next-Generation Grid Support over the SIP/IMS Platform 1 1All. the. related. represented. functions. required. to. provide. network. services. in. a. Grid-compliant. manner. reside. in. the. NP. domain,. thus. creating. a. new. environment.where.Grids.meet.the.semiwalled.garden.business.model..The. available. accounting. and. charging. activities. on. this. domain. are. ready. to. account. and. charge. for. Grid. services. as. well,. which. finally. makes. the. network. domain. basically. ready. to. deploy. Grid. services. commercially. on. its. infrastructure..Also,.NP.elements.manage.the.identity.of.the.users,.authenti-

cating.them.and.providing.this.authentication.service.to.the.BVO.(and.thus. to.the.OpVOs.and.SPs).

Integrating IMSs SIP Infrastructure and Grids: Mobile and Dynamic Grid Environment

Involved Protocols: SIP and SOAP

The. SIP. [9]. is. a. protocol. targeted. to. the. establishment,. modification,. and. termination. of.sessions.. In.the. context. of.SIP,.a.session. is. understood.as.an. association. created. between. two. or. more. participants. to. interchange. some. kind.of.data..SIPs.specification.only.defines.the.signaling.messages.and.the. operation. of. the. protocol,. decoupling. it. from. the. actual. type. of. data. to. be. exchanged.once.a.session.has.been.successfully.established..Also,.the.parameters.that.characterize.the.session.to.be.negotiated.by.the.participants.during. the.session.setup.are.described.using.the.Session.Description.Protocol.(SDP). [10],. which. is. transported. as. payload. in. SIP. messages. (Figure.6.5).. Despite. this.decoupling,.SIP.has.been.traditionally.used.to.manage.multimedia.sessions.such.as.voice.over.IP.(VoIP).telephone-like.calls..Also,.the.SDP.descrip- tions.available.mainly.relate.to.this.kind.of.multimedia.session,.describing,. for.instance,.the.media.codecs.to.employ.in.the.sessions.Considering.that.it.is.conceived.to.support.any.kinds.of.applications,.SIP. has. been. designed. by. the. IETF. to. be. used. as. a. signaling. framework. in. IP. networks.. Thanks. to. its. inclusion. in. the. IMS,. SIP. is. currently. the. de. facto. standard.for.signaling.in.next-generation.networks.SIP.functionality.makes.it.especially.useful.in.mobile.and.ubiquitous.environments.. In. such. environments,. users. can. move. and. change. the. terminal. they.are.using.to.access.the.services..The.SIP.infrastructure.tracks.each.user. in.order.to.keep.the.information.about.its.(logical).location.updated.The.key.signaling.protocol.for.Grids.and.virtual.organizations.is.the.SOAP. [11]..SOAP.is.a.lightweight.message-based.protocol.intended.for.exchanging. structured. information. in. a. decentralized,. distributed. environment. over. a.

GenericApplication GenericApplication

SIP_session_setup_negotiation Application_typically_multimedia_(RTP/RTCP)_but_can_be_any SIP_session_tear_down

FIGure 6.5SIP.is.decoupled.from.the.application.

variety.of.underlying.protocols..SOAP.enables.the.binding.and.usage.of.dis- covered.Web.services.by.defining.a.message.path.for.routing.messages..We. consider.stateful.(enabled.by.WSRF).and.session-aware.SOAP.Grid.services. in.this.chapter..For.the.integration.of.SIPIMS.and.stateless.Grid.services,.the. reader.can.check.reference.7.

Integrating SIP and SOAP

As.we.discussed,.making.Grids.mobile.and.dynamic.is.of.great.advantage.. However,.the.SOAP.protocol.used.by.Web.services.(the.framework.used.by. Grids). is. not. as. well. prepared. for. this. as. SIP.is.. Besides,.one. of. the. goals. is. to.involve.users.(logged.to.their.devices).in.service.provision.(like.providing. medical. first. aid. during. a. disaster. scenario). and. integrating. SIP. controlled. user-to-user. communications.. This. is. why. the. best. approach. is. to. keep. SIP. and.integrate.SOAP.with.it..Thanks.to.the.SIPSOAP.interaction,.SIP.information.such.as.the.current.location,.as.well.as.notifications.about.the.status. of.mobile.services.being.run.by.users.previously.registered.in.the.SIP.server,. is.propagated.to.the.Grid.layer.and.vice.versa..In.this.way,.the.Grid.layer.can. keep.track.of.the.mobile.users.and.readjust.to.changes.on.the.fly..SIPSOAP. interaction.can.be.implemented.in.two.ways:

A. SIP. Application. Programming. Interface. (API). can. be. provided. to. the. Grid. applications.. These. applications. will. then. issue. SIP. signaling. messages. directly. to. the. appropriate. SIP. entities;. that. is,. a. SIP. User. Agent. (SIP. UA). is. integrated. in. the. Grid. application.. Once. the. session.is.set.up.using.SIP,.SOAP.messages.will.be.used.during.the. session.. This. is. just. like. other. applications. (such. as. VoIP). using. SIP. work..This.approach.is.the.cleanest.one.in.terms.of.architecture.but. implies. the. modification. of. Grid. applications. in. order. for. them. to. interact. directly. with. the. SIP. infrastructure,. instead. of. using. SOAP. messages. Some.intermediate.entities.will.be.provided;.these.will.be.invoked,. using. SOAP,. by. the. Grid. applications.. These. entities. will. issue. the. needed.SIP.methods.(REGISTER,.INVITE,.BYE,.).on.behalf.of.the. Grid.applications,.even.establishing.Grid.sessions.on.behalf.of.them.. This.approach.will.ease.the.implementation.of.the.Grid.applications. because.they.will.use.regular.SOAP.messages.(directed.to.the.intermediary.entities).even.for.SIP-related.methods.

Next-Generation Grid Support over the SIP/IMS Platform 1 3Because.SIP.is.used.to.negotiate.the.setup.of.Web.services.Grid.sessions,. the. language. describing. the. parameters. to. be. negotiated. (SDP). must. be. tailored.to.these.kinds.of.applications..SDP.(like.SIP).was.designed.to.support.the.definition.of.any.kind.of.session.(although.the.most.common.use.is. multimedia. communications). by. means. of. standardized. extension. mechanisms,. so. no. special. adaptation. effort. is. needed. to. describe. Grid. sessions. using.SDP..We.can.call.this.description,.for.ease.of.understanding,.Grid.ses-

sion.description..One.of.the.main.parameters.to.negotiate.(described.in.the. Grid.session.description).is.the.Web.Service.Description.Language.(WSDL). [12]. file. that. describes. each. service. involved.. WSDL. is. used. to. describe. the. methods. offered. by. a. given. service.. WSDL. files. also. contain. the. End. Point. Reference.(EPR).of.the.service.(i.e.,.where.the.service.can.be.located.in.order. to.consume.it)..After.the.session.setup.negotiation,.the.Grid.session.participants.will.come.to.know.the.public.methods.and.EPRs.of.every.other.service. they.are.using.in.this.session..To.allow.this.interaction,.a.new.SDP.attribute. (the.WSDL.attribute).is.defined.[13]..This.attribute.contains.the.URL.where. the.services.WSDL.file.can.be.retrieved..We.will.detail.this.negotiation.later. in.this.chapter.From. a. service. provisioning. point. of. view,. an. interface. needs. to. be. provided.to.Grid.applications.for.the.following.methods:

At. start-up. phase,. mobile/ubiquitous. services. will. be. associated. with.a.certain.SIP.Uniform.Resource.Identifier.(SIP.URI),.which.has. been. previously. registered. in. the. SIP. registrar. (the. S-CSCF). with. the. SIP. REGISTER. method.. This. SIP. URI. can. simply. be. the. URI. of. the.user.logged.in.to.the.Mobile.Terminal.(MT).where.the.services. are.running.or.a.special.URI.representing.the.services..In.any.case,. within.the.context.of.the.SIPSOAP.synergies,.we.will.refer.to.it.as. service.URI.from.now.on. The. Grid. applications,. instead. of. using. EPRs,. as. stated. in. Web. service. addressing. [4]. for. identifying. resources,. should. use. in. the. establishment. phase. SIP. URIs. for. identifying. mobile/ubiquitous. services.(EPRs.are.not.suitable.for.identifying.resources.that.change. frequently.in.ubiquitous.environments),.so.that.they.will.send.a.SIP. INVITE. to. the. service. URI.. This. SIP. INVITE. message. will. contain. special.values.in.its.SDP.payload.so.that.it.will.be.identified.as.a.Grid. session.description.by.the.recipient.of.the.INVITE.message. In. the. SIP. answer,. again. by. means. of. an. SDP-based. Grid. session. description,. the. Grid. application. will. get. the. needed. Grid. session. information.to.start.the.Grid.invocations.(i.e.,.the.WSDL.file.describing.the.service.and.its.EPR).

Also,.Grid.applications.could.include.the.adequate.logic.for

using.further.session.management.features.provided.by.SIP.such.as. session.save/load/restore,.useful.also.for.session.transfer..There.are. already. some. proposals. for. this. feature. (Web. services. continuity),. like.the.approach.presented.in.reference.14;.and reacting.to.context.changes.that.are.notified.with.SIP.

The.next.section.describes.in.a.general.way.how.the.solution.works..This. description. can. be. applied. to. any. of. the. options. listed. before. to. achieve.

SIPSOAP. interaction:. patching. the. Grid. applications. to. employ. a. SIP. API. or.using.intermediary.entities..To.show.both.solutions.(that.are.conceptually. similar),.we.assume.that.the.Grid.applications.in.the.MTs.have.been.patched. to.use.SIP.and.that.the.Grid.applications.in.the.service.providers.employ.an. intermediary. entity. located. in. an. independent. node,. the. SIPSOAP. broker.. The. SIPSOAP. broker. can. be. considered. as. an. IMS. AS. (application. server). that.offers.a.Web.services.WSSOAP.interface.to.the.Grid.applications.in.the. SP.and.a.SIP.interface.to.the.IMS.SIP.infrastructure.(the.[S-CSCF])..For.read- ability. reasons,. we. consider. that. the. MTs. send/receive. their. SIP. messages. directly. to/from. the. S-CSCF;. actually,. in. the. IMS,. these. messages. first. tra- verse.the.Proxy.Call.State.Control.Function.(P-CSCF),.which.is.the.terminals. contact.point.for.SIP.messages.

SIP Support for SOAP-Based Grid Services

Initialization

During.the.MTs.start-up,.the.Grid.services.and.the.SIP.UA.that.will.act.on. behalf. of. the. Grid. services. running. in. the. terminal. are. started. following. the.depicted.sequence.(Figure.6.6;.right.side.of.picture)..The.SIP.UA.start-up. involves.a.SIP.registration.and.a.SIP.presence.publication,.in.order.to.make. visible. the. MT. for. other. Grid. services. that. could. be. interested. in. the. Grid. applications.running.on.it..After.the.SIP.UA.starts,.the.MT.will.be.ready.to. provide.information.about.the.grid.services.running.on.it..The.service.URI. to.be.used.will.be.the.SIP.URI.used.during.the.SIP.registration.The. SP. must. also. register,. but. we. must. bear. in. mind. that. although. the. Grid.services.offered.by.users.logged.in.to.their.devices.are.in.an.extremely. dynamic.environment.(users.move,.change.their.terminals,.disconnect,.etc.),. the.services.offered.in.Grid.service.providers.are.far.more.static.After. the. initialization,. the. Grid. services. will. be. ready. to. receive. WSRF. notifications.

Setting Up Sessions Involving Services Running in MTs

EPR. is. the. way. Grid. and. SOAP. reference. the. services;. in. SIP. this. is. done. using. URIs.. The. services. (Grid. or. not). offered. within. the. IMS. service. platform.are.indexed.in.the.SIP.registrar,.a.module.of.the.IMSs.S-CSCF.The.main.result.of.the.session.setup.negotiation,.carried.on.using.SIP.and. SDP,. between. GridSOAP. nodes. is. that. session. participants. will. come. to. know.the.EPRs.of.the.services.they.are.using.in.this.session.as.well.as.their. public.interfaces..Figure.6.7.illustrates.this.session.setup.

1 IP Multimedia Subsystem (IMS) Handbook When. the. Grid. SP. needs. to. know. the. EPR. of. a. service. running. on. an. MT,. it. indicates. which. service. it. is. interested. in. (ServiceID). and. the.SIP.URI.being.used.by.the.MT.in.which.the.service.is.expected.

S-CSCF

GRID_SP SIP-SOAP_AS

SIP_Presence-Agent

SIP_Registrar SIP_UA_Term GRID_Apli_Term

WS_SUBSCRIBE_SOAP()

REGISTER_SIP(URI)

PUBLISH_SIP(Status)

WS_SUBSCRIBE_API()

1 Next-Generation Grid Support over the SIP/IMS Platform REGISTER_SIP(URI)

PUBLISH_SIP(Status)

FIGure 6.6Registration.of.Grid.services.to.the.S-CSCF.

S-CSCF

GRID_SP SIP-SOAP_AS

SIP_Presence-Agent

SIP_Proxy

SIP_UA_Term

GRID_Apli_Term

WS_getConnectionDetails_SOAP(ServiceID, URI)

INVITE_SIP()

INVITE_SIP()

WS_getConnectionDetails_API()

WS_getConnectionDetailsReturn_API(WSDL_URL)

200-OK_SIP()

200-OK_SIP()

WS_getConnectionDetailsReturn_SOAP(WSDL_URL)

ACK_SIP()

ACK_SIP()

IP Multimedia Subsystem (IMS) Handbook1 SUBSCRIBE_SIP(URI) NOTIFY_SIP(Status)

WS_invokeService_SOAP(EPR, method)

WS_invokeServiceReturn_SOAP(Result)

FIGure 6.7SIP-based.Grid.session.establishment.and.service.invocation.

to.be.running..The.Grid.SP.can.also.request.all.services.running.in. a.given.terminal. The.SIPSOAP.AS.starts.a.Grid.session.setup.with.the.required.MT..Finally,. the. required. information. (WSDL_URL). is. returned. to. the.Grid.SP..This.information.is.then.used.by.the.Grid.SP.to.retrieve.the.WSDL.file.that.describes.the.service,.using.HTTP.or.any.other.regu-lar.mechanism.(this.interaction.is.not.depicted.in.the.figure). At. this. point,. the. Grid. SP. knows. the. EPR. to. be. used. in. order. to. invoke.the.service.or.services.it.is.interested.in. Additionally,. the. SIPSOAP. AS. performs. a. subscription. to. the. SIP. presence. information. of. the. service. SIP. URI;. in. this. way,. it. will. be. aware.of.the.availability.status.of.the.whole.terminal.and.may.report. changes.to.the.Grid.SP..Note.that.the.terminal.may.also.be.interested. in.knowing.the.status.of.the.services.offered.in.the.Grid.SP,.but.the. Grid.SP.status.is.very.static.compared.to.the.services.offered.by.the. terminal..That.is.why.the.Grid.SP.subscribes.to.the.terminal.status. but.the.opposite.does.not.occur.

Disconnection and Reconnection of Terminals and Their Services; Mobility

Because. the. SIPSOAP. AS. is. aware. of. the. terminal. status,. it. can. use. this. informationfor. example,. to. inform. the. Grid. SP. if. the. user. disconnects. from. one. location. and. then. connects. from. a. different. one. or. with. a. different. terminal. (or. if. the. user. simply. disconnects). [6].. Using. this. feature,. the. Grid.SP.can.make.an.appropriate.decision,.like.selecting.different.services.or. refreshing.the.information.at.the.new.service.location..This.is.the.behavior. described.in.Figure.6.8.First,.a.controlled.disconnection.from.terminal.1.occurs..From.the.point.of. view.of.the.services.SIP-based.support,.the.most.relevant.steps.are:

The.SIPSOAP.AS.informs.the.Grid.SP.about.the.SIP-based.Grid.session.termination.using.the.SOAP.message.WS_NOTIFY.notification,. indicating.that.all.services.running.at.the.MT.become.unavailable. The. presence. agent. informs. about. changes. on. the. presence. status. while. the. presence. subscription. done. by. the. SIPSOAP. AS. during. the.Grid.session.setup.phase.remains.active.

Next-Generation Grid Support over the SIP/IMS Platform 1 Then. the. service. URI. is. used. to. connect. again. from. another. location.. Thanks. to. the. active. presence. subscription,. the. SIPSOAP. AS. detects. that. the.presence.status.of.the.associated.service.URI.is.online.again.and.it.can. report.on.this.to.the.Grid.SP..Typically,.the.Grid.SP.will.request.the.service. details.again.at.the.new.location,.setting.up.a.new.Grid.session.as.we.saw.in. the.previous.section.

S-CSCF

Terminal1 Terminal2

GRID_SP SIP-SOAP_AS

SIP_Presence-Agent

SIP_Registrar

SIP_Proxy SIP_UA_Term GRID_Apli_Term

SIP_UA_Term2 GRID_Apli_Term2

WS_NOTIFY_API(ServiceStatus)

WS_NOTIFY_SOAP(ServiceStatus)

BYE_SIP()

200_OK

UNPUBLISH_SIP()

BYE_SIP()

200_OK

NOTIFY_SIP(Status)

UNREGISTER_SIP(URI)

REGISTER_SIP(URI)

WS_SUBSCRIBE_API()

NOTIFY_SIP(Status) WS_NOTIFY_SOAP(ServiceStatus)

PUBLISH_SIP(Status)

IP Multimedia Subsystem (IMS) Handbook1

FIGure 6.8User.disconnection.and.reconnection.from.another.location.

Accidental Disconnection

In.the.case.of.an.accidental.disconnection,.the.Grid.SP.will.be.aware.of.this.sit- uation.because.the.SIPSOAP.AS.will.receive.a.SIP.presence.notification.indicating.that.the.presence.status.of.the.service.URI.has.expired..This.event.will. be.interpreted.as.an.incidental.disconnection.and.the.Grid.SP.will.be.informed. about.the.complete.services.unavailability.at.the.corresponding.URI.

Changes in Services in the Terminals While the Session Is Running

The.established.SIP.session.will.be.used.as.the.main.mechanism.to.inform.the. Grid.SP.about.changes.on.the.MT.grid.services.availability.or.EPRs..Thus,.if. the.information.related.to.some.service.changes,.the.MTs.SIP.UA.will.send. a. reINVITE. containing. the. new. Grid. session. description.. The. Grid. SP. will. be.informed.of.this.through.a.WS_NOTIFY_SOAP.message,.whose.content. indicates.a.change.in.the.services..This.sequence.is.depicted.in.Figure.6.9.

Session Teardown

When.the.services.running.on.certain.MTs.are.no.longer.needed,.the.Grid.SP.can. terminate.an.existing.SIP.Grid.session..In.this.case,.the.SIP.presence.subscription.from.the.Grid.SP.to.know.the.status.of.the.terminal.is.also.terminated.

Integrating Grid Services and SIP-Controlled Audio/Video Calls

For. a. third. party. to. set. up. a. SIP. session. (typically. a. voice. call). between. two.other.parties,.two.options.are.available:.third-party.call.control.(3PCC;. described.in.reference.15).or.using.the.SIP.REFER.method..We.will.concen- trate.on.the.latter.in.this.section.(Figure.6.10).

S-CSCF

GRID_SP SIP-SOAP_AS SIP_Proxy SIP_UA_Term GRID_Apli_Term

Next-Generation Grid Support over the SIP/IMS Platform 1 WS_NOTIFY_API(ServiceStatus)

INVITE_SIP()200-OK_SIP()

ACK_SIP() WS_NOTIFY_SOAP(ServiceStatus)

INVITE_SIP()

200-OK_SIP() ACK_SIP()

FIGure 6.9Change.on.services.

S-CSCF

Terminal 1 Terminal 2

SIP_Presence-Agent

GRID_SPSIP-SOAP_ASWS_getConnectionDetails_SOAP(URI_1, URI_2)

SIP _Registrar

SIP_Proxy SIP_UA_Term 1

VoIP 1

SIP_UA_Term 2

VoIP_2REFER(INVITE_2)

REFER(INVITE_2)202-AC_SIP()202-AC_SIP() INVITE_SIP()200-OK_SIP()

NOTIFY_SIP(Status) WS_getConnectionDetailsReturn_SOAP(Success)

NOTIFY_SIP(Status)

ACK_SIP()

AudioVideo-flows_RTP/RTCP() AudioVideo-flows_RTP/RTCP()

IP Multimedia Subsystem (IMS) Handbook1 0

FIGure 6.10Grid-initiated.calls.using.REFER.

As. part. of. the. orchestrated. execution. of. several. services. within. a. Grid. environment,. a. call. between. two. terminals. may. be. needed.. However,. this. voice. call. is. not. a. Grid. Web. service. but,. rather,. a. multimedia. application. using. the. Real-Time. Transport. Protocol. (RTP)/Real-Time. Transfer. Control. Protocol. (RTCP). and. not. the. SOAP. protocol.. The. solution. to. integrate. this. call.in.the.Grid.service.environment.is.described.as.follows:

During. a. Grid. service. execution,. a. Grid. application. in. the. SP. may. receive.the.query.to.put.in.contact.users.1.and.2. After. requesting. the. SIP. URIs. of. the. involved. users,. it. sends. a. SIP.REFER.message.to.user.1.through.the.S-CSCF,.indicating.that.a.ses-sion.with.user.2.should.be.initiated. The.S-CSCF.redirects.the.REFER.to.the.MT.or.MTs.where.user.1.is. logged.in. If.the.session.setup.is.accepted.on.user.1.MT,.it.sends.a.202.Accepted. response.and.starts.a.standard.session.setup.process.with.user.2.MT.. Note. that. SIP. messages. will. follow. the. path. user. 1. P-CSCF. S-CSCF. P-CSCF. user.2;.for.easy.reading,.we.draw.the.SIP.messages.as.going.directly.from.user.1.to.user.2. The. Grid. SP. is. informed. about. the. session. progress. via. NOTIFY. messages. because. the. REFER. method. creates. an. implicit. subscription.to.the.status.of.users.1.and.2. When.the.Grid.SP.is.informed.about.the.session.establishment.success,.the.process.finishes.

Integrating Grid with the Network OperatorInfrastructure Reusing IMS -Defined Interfaces

Roughly. speaking,. IMS. Call. State. Control. Functions. (CSCFs). are. advanced. SIP. proxies. controlling. the. application. sessions. between. different. entities.. Those.entities.use.SIP.to.set.up.their.sessions.and.involve.the.IMSs.CSCFs. in.this.session.setup..One.of.the.most.prominent.characteristics.of.the.IMS.is. that.it.defines.interfaces.between.the.CSCFs.and.some.nodes.from.the.Uni- versal.Mobile.Telecommunication.System.(UMTS).network.

1 2 IP Multimedia Subsystem (IMS) HandbookThe.first.interface.we.consider.is.related.to.user.control..The.UMTSs.home. subscriber. system. (HSS). performs. user. control. and. authentication;. IMS. defines. an. interface. between. CSCFs. and. HSS. so. that. the. CSCFs. can. dele- gate.the.user.control.to.the.operators.HSS..Similarly,.the.Charging.Gateway. Function. (CGF). is. a. network. operator. node. performing. accounting. for. network.resources.(e.g.,.bytes.sent.by.the.user)..The.IMS.defines.another.interface.between.the.CSCFs.and.the.CGF..The.IMSs.CSCFs.will.send.to.the.CGF.

accounting. data. related. to. the. SIP. sessions. that. the. CSCFs. control.. These. data.may.include,.for.instance,.the.type.of.the.call.between.the.users.(audio. or.audio/video)..Thus,.CGF.receives.accounting.data.from.different.sources. and.from.different.levels.(e.g.,.bytes.sent/received.and.type.of.call.between. the. users. [audio. or. audio/video]).. CGF. is. capable. of. correlating. these. two. levels. and. producing. an. aggregated. billing.. The. last. interface. we. consider. is.that.defined.between.the.CSCFs,.which.know,.for.instance,.that.the.users. will. employ. a. codec. that. requires. 16. kbps. for. their. voice. call,. and. the. network. nodes. that. will. transport. this. voice. call.. Thanks. to. this. interface,. the. network.nodes.will.be.tailored.to.accommodate.this.voice.call.The.Grid.SPs.within.the.BVO.(and.thus.with.agreements.with.the.NP).will. be. able. to. employ. these. three. mentioned. interfaces. (with. minimal. modifi- cations);. see. Figure.6.11.. This. will. be. done. when. an. OpVO. is. instantiated. within.the.BVO.and.the.services.of.a.service.provider.are.needed.within.this. Grid.environment.(the.OpVO).In.the.next.sections.we.will.detail.the.three.aforementioned.interfaces..We. must. stress. that. because. SIP. support. is. included. in. the. Grid. environment. and,.as.such,.the.Grid.uses.the.IMS.CSCFs,.those.CSCFs.may.tackle.the.three. aspects. mentioned. earlier. directly,. as. in. pure. IMS. solutions.. The. approach. where.the.Grid.environment.itself.deals.with.these.aspects.using.the.three. mentioned.interfaces.will.streamline.the.process.of.Grid.services.provision.

PDF/PCrF Interface to Grid Service Provider

IMSs. CSCFs. interact. with. the. network. Policy. and. Charging. Enforcement. Function.(PCEF).(routers.or,.in.UMTS.networks,.the.Gateway.General.Packet.

ServiceProvider

Reuse these Protocols

IMS Services SIP SessionsControl

CSCFsto Interface with theService Providers

Open, StandardizedInternet Protocols

HSS, CGF,

UMTS. Data Transport Control. User Control (Authentication, Authorization, Accounting)

User Services (e.g., First-aid Capabilities)

FIGure 6.11Reuse.of.IMSs.CSCF.interfaces.to.UMTS.network.nodes..SPs.access.the.network.nodes.

Radio. Service. [GPRS]. Support. Node. [GGSN]). via. the. Policy. and. Charging. Rules.Function.(PCRF;.Policy.Decision.Function.[PDF].in.older.IMS.releases).. We.plan.to.reuse.the.CSCF.to.PCRF.interface.for.the.interaction.between.the. Grid. SPs. and. the. PCRF.. The. Grid. SPs. employ. the. SOAP. protocol,. and. the. mentioned.interface.is.based.on.the.DIAMETER.protocol..Like.the.SIPSOAP. interaction. explained. in. previous. sections,. two. possibilities. (illustrated. in. Figure.6.12).arise.to.make.SOAP.and.DIAMETER.cooperate:

An.API.is.provided.to.the.Grid.SPs.and.their.code.is.patched.to.use. this.API..When.a.Grid.session.is.to.be.set.up,.by.a.call.to.this.API,.a. DIAMETER.message.is.sent.to.the.PCRF.to.allow,.subsequently,.the. user. to. make. transport. resource. reservations. to. accommodate. the. flows.of.the.Grid.session. An.independent.module.is.developed.with.a.SOAP.interface.to.the.Grid.SPs.and.a.DIAMETER.interface.to.the.IMSs.PDF..This.module.exposes. some. of. the. functionality. of. the. PDF. as. a. Grid. service. (a.Web.service,.actually),.ready.to.be.used.by.the.Grid.SPs..When.they.need.to.authorize.the.use.of.network.resources.for.a.subsequent.Grid.service,.they.will.issue.a.SOAP.request.to.this.independent.module..

DIAMETER

PDF/PCRF

CSCFs

IMS Network

Grid Service Provider Patched with API to Interact with PDF

PCEF (Router/GGSN)

Module Exposing PDF Functionality as a Web Service

SOAP

PDF/PCRF

CSCFs

IMS Network

Grid ServiceProvider

DIAMETER

PCEF (Router/GGSN)

FIGure 6.12Possibilities.for.a.Grid.Web.service.to.make.resource.reservation.in.IMS.

This. module. will. translate. this. request. to. a. DIAMETER. message. sent.to.the.IMSs.PCRF.

Because.SIP.support.has.been.included.in.the.Grid.environment,.this.transport.resource. authorization. can.be.tackled. directly. by.the.IMS.SIP.proxies,. in. particular. by. the. P-CSCF.. Also,. because. the. P-CSCF. may. be. located. in. the.visited.domain,.roaming.issues.are.solved..The.preceding.method.will,. however,.streamline.the.Grid.session.creation.process.and,.moreover,.leave. more.control.to.Grid.nodes.over.the.needed.transport.resources..Taking.into. account. that. the. Grid. environment. is. especially. dynamic. (because. of. the. mobile.terminals),.this.is.of.great.importance.

Interfaces to the HSS and CDF for user Control

In.this.section.we.detail.aspects.related.to.user.control.(authentication,.authorization,. accountingAAA).. Every. SP. has. an. accounting. server. collecting. accounting.data..With.these.data,.the.server.will.create.accounting.records;. the. most. common. protocol. to. transmit. these. records. is. DIAMETER,. which. is. also. used. in. IMS. for. these. purposes.. The. Grid. SP. can. send. its. accounting. records. to. the. IMSs. Charging. Data. Function. (CDF);. as. in. regular. IMS. sessions,. the. CDF. will. send. accounting. information. to. the. operators. CGF,. which.will.aggregate.this.accounting.information.(at.application.level).with. accounting. information. from. the. network. level. (e.g.,. bytes. sent).. However,. so.as.not.to.overload.the.CDF.with.data.coming.from.all.the.service.providers,.in.each.BVO.an.intermediate.accounting.node.should.be.present..It.will. collect.accounting.information.from.the.Grid.service.providers.and.send.it,. aggregated,.to.the.CDF,.as.illustrated.in.Figure.6.13.Because. the. Grid. SPs. interact,. using. SIP,. with. the. S-CSCF. (as. we. saw. in. previous. sections),. the. S-CSCF. could. also. be. in. charge. of. sending. these. accounting.data.to.the.CDF,.as.is.done.in.regular.IMS.scenarios..Even.more,. if.we.use.an.AS.to.achieve.the.SOAP.(protocol.used.by.the.Grid.SPs).with.SIP. interaction,.it.could.be.that.this.AS.is.the.one.sending.the.accounting.data.to.

Next-Generation Grid Support over the SIP/IMS Platform 1

AccountingCollection Module

CDF

CSCFs

DIAMETER

Grid ServiceProvider

DIAMETER

IMS Network

CGF

FIGure 6.13Accounting.for.Grid.Web.services.in.IMS.

the. CDF.. Although. this. would. require. no. further. changes,. it. may. overload. the.IMS.more.than.the.previous.approach.With.respect.to.user.authentication.and.authorization,.the.same.two.possibilities.exist:

The.Grid.SPs.contact.the.network.operators.HSS.directly. Because. the. Grid. has. SIP. support,. this. contact. can. be. done. by. the.IMSs.S-CSCF.

Conclusion

IMS. is. a. well-designed. service. platform. that. grants. the. network. operator. the.role.of.service.broker..Multimedia.calls.are.a.service.inherent.to.IMS,.but. many.more.services.should.be.developed.on.top.of.the.IMS.service.platform. to.build.a.rich.service.environment.enticing.the.users.to.employ.it..Integrat- ing.the.Grid/Web.services.environment.into.the.IMS.will.broaden.the.possibilities.to.offer.a.rich.service.portfolio.in.the.IMS.This. integration. is,. however,. not. trivial. because. the. IMS. session. control. protocol.is.SIP,.and.Grid/Web.services.employ.SOAP..Also,.Grids.were.never. biased.into.a.commercial.world..In.this.chapter.we.presented.how.to.make. this.integration.possible.and.the.benefits.that.it.will.bring..This.is.one.of.the. multiple.steps.to.build.a.rich.service.environment.based.on.the.IMS.

References. 1.. Cuevas,.A..et.al..2006..The.IMS.service.platform,.the.key.for.next-generation.network.operators.to.be.more.than.bit.pipes..IEEE Communications Magazine.44(8),.7581.. 2.. The.Parlay.Group..http://www.parlay.org. 3.. Open.Mobile.Alliance..http://www.openmobilealliance.org/. 4.. Globus.Alliance..The.WS-resource.framework..http://www.globus.org/wsrf/. 5.. Globus.Alliance..OGSAThe.open.grid.services.architecture..http://www.glo-bus.org/ogsa/. 6.. Waldburger,.M..et.al..2006..Towards.the.mobile.Grid:.Service.provisioning.in.a.mobile.dynamic.virtual.organization..4th ACS/IEEE International Conference onComputer Systems and Applications.(AICCSA-06),.Dubai,.UAE,.March.. 7.. Levenshteyn,.R..et.al..Mobile.services.interworking.for.IMS.and.XML.Web.ser-vices..2006..IEEE Communications Magazine.44(9),.8087.. 8.. The.Akogrimo.project..http://www.akogrimo.org. 9.. Rosenberg,.J..et.al..2002..SIP:.Session.initiation.protocol,.IETF.RFC.3261.. 10.. Handley,.M..et.al..2006..SDP:.Session.description.protocol,.IETF.RFC.4566.

. 11.. World. Wide. Web. Consortium. (W3C).. SOAP. specifications.. http://www. w3.org/TR/soap/. 12.. World. Wide. Web. Consortium. (W3C).. Web. services. description. language. (WSDL)..http://www.w3.org/TR/wsdl/. 13.. Olmedo,.V..et.al..2007..The.Session.Description.Protocol.(SDP).WSDL.attribute..IETF.Internet.draft.(work.in.progress).. 14.. Dorn,.C.,.and.S..Dustdar..2006..Achieving.Web.service.continuity.in.ubiquitous.mobile. networks:. The. SRR-WS. framework.. 4th International Workshop on Ubiq-uitous Mobile Information and Collaboration Systems (UMICS),. co-located. with.CAiSE.2006,.June.56.. 15.. Rosenberg,.J..et.al..2004..Best.current.practices.for.third-party.call.control.(3pcc).in.the.session.initiation.protocol.(SIP),.IETF.RFC.3725.

Documents

(531784349) Chapter 6 Pages From IP Multimedia Subsystem (IMS) Handbook 2009