Initial Response to Telecom Wireless RFP telecom000501

1
Initial Response to Telecom Wireless
RFPtelecom/00-05-01

• Kimmo Raatikainen
• Nokia Research Center
• (Department of Computer Science, University of
  Helsinki)

2
Presentation Outline - 1/2

• Prelude
• Contact persons, response to RFP, design
  rationale
• Architectural Framework
• usage framework, wCORBA extensions
• GIOP mappings
• onto UDP, onto WAP Wireless Transaction Protocol
  (WTP)
• Wireless CORBA Extensions
• Location Transparent IOR, Bootstrapping the
  terminal, Initial access, Interface to visited
  NS, Home Location Register
• Handoff and Access Recovery

3
Presentation Outline - 2/2

• Issues to be discussed
• Notification Service Mobility Events
• Interoperable Naming Service
• Messaging Service
• Other ORB Services Generic Invitation Service
• Homeless Terminals
• Conformance Points
• Conclusions

4
Contact Persons

• Nokia Kimmo Raatikainen
• kimmo.raatikainen_at_nokia.com
• Vertel Shahzad Aslam-Mir
• sam-aslam-mir_at_vertel.com
• Sonera Jouni Korhonen
• jouni.korhonen_at_sonera.com
• University of Helsinki Kimmo Raatikainen
• kimmo.raatikainen_at_cs.helsinki.fi

5
RFP Requirements - 1/2

• Architectural framework
• GIOP mapping onto Internet transport protocol
  (TCP or UDP) over wireless links
• Mechanism that hides from CORBA clients the
  mobility of terminals on which CORBA servers are
  running
• Mechanism for initial access to a new mobility
  domain
• Mechanism for finding the necessary basic set of
  CORBA services in mobility domain
• Mechanism for advertising CORBA services
  available on a mobile terminal
• Mechanism for handoff between mobility domain
• All these requirements are addressed.

6
RFP Requirements -2/2

• This response proposes a GIOP mapping onto WAP
  Wireless Transaction Protocol WTP
• This response discusses usage of
• Notification Service,
• Interoperable Naming Service, and
• Messaging Service.
• The response also discusses usage of other ORB
  Services.

7
Design rationale

• Design is based on the results from the EC/ACTS
  project DOLMEN
• DOLMEN specified and implemented a prototype
  based on CORBA 2.0
• This response takes advantage of CORBA 2.3
  features
• Target is a general framework for mobility - not
  only terminal mobility but an object group
  mobility
• some of the complexity may be removed if only
  terminal mobility would be addressed (one object
  group in a terminal)
• Wireless access without (ORB-level) mobility as a
  well-defined subset serves also for UDP-mapping
  in WANs
• Reuse of IETF defined session protocol

8
Architectural Framework
9
(No Transcript)
10
Assumptions - 1/2

• In order to exploit all features specified in
  this proposal CORBA applications (or generic ORB
  application libraries) on mobile terminals need
  to be aware of mobility.
• Each terminal is an ORB domain of its own.
• Terminals attach to other ORB domains through an
  access node that implements a low-level
  interoperability bridge called Wireless Access
  Bridge (WAB)
• A Wireless Access Bridge may support ES-IOPs for
  mobile terminals.

11
Assumptions - 2/2

• A terminal may have a home domain, in which a
  Home Location Register interface is implemented.
• The Home Location Register provides the means to
  find the Wireless Access Bridge to which the
  terminal is currently attached.
• A Wireless Access Bridge may provide a temporary
  HLR for "homeless" terminals

12
Domain Definition

• RFP mobility domain to denote a domain that
  allows access from mobile terminals and provides
  them ability to use and to offer CORBA-based
  services is sufficient.
• We do not use the term mobility domain.
• Instead, we use the term visited domain in a
  similar sense.
• A visited domain consists of one Wireless Access
  Bridge and a set of CORBA Services that are
  available through a Wireless Access Bridge.
• It should be noted that two or more Wireless
  Access Bridge can share the set of CORBA Services
  available through them.
• Therefore, a single instance of a CORBA Service
  can be available through several visited domains.

13
Bridge associations
14
Wireless CORBA Extensions
15
Terminal domain
16
Mobile Terminal Bridge

• terminal bootstrap
• initial access
• handoff
• access recovery
• GIOP/UDP mapping
• optionally the GIOP/WAP mapping

17
ORB Service Agent

• provides the means of transparently accessing
• Naming Service and other ORB services in the
  visited domain.
• The binding of names into the Naming Service in
  the visited domain that are automatically rebind
  to the Naming Service in the new visited domain
  after a handoff.
• The binding of names into the Naming Service in
  the home domain the IORs of which are
  automatically updated domain after a handoff.
• For the other ORB services the handoff is only
  semi-automatic.
• The old references are stalled but new references
  need explicit involvement of the application.

18
Mobility Event Supplier

• mandatory part of the proposed technology in the
  terminal domain
• generates notifications of
• handoffs,
• connectivity drops, and
• connectivity recoveries.
• an optional feature in the visited domains

19
Visited domain
20
Wireless Access Bridge

• Counterpart of the Mobile Terminal Bridge in the
  access network domain.
• implements the support of the mandatory parts of
  the mobile terminal including support
• initial access,
• visited domain services,
• location transparent IORs,
• ORB Service Agent,
• handoff and
• access recovery.

21
Home domain
22
Home Location Register

• provides the means of keeping track of the
  current location
• the Wireless Access Bridge in current visited
  domain.
• provides the means of accessing the ORB Services
  in the home domain, even if the access is through
  a visited domain.
• The HLR interface also provides the means of
  updating the references available through the
  Naming Service in the home domain.
• May support paging
• Must have the paging method
• but it can raise exception PagingNotSupported

23
GIOP mappings

• onto UDP based on IETF Stream (aka Simple)
  Control Transmission Protocol (SCTP) proposal
• onto WAP Wireless Transaction Protocol Class 1

24
Wireless IOP

• GIOP mapping onto UDP
• UDP is an unreliable connectionless datagram
  (message-based) transport service
• a protocol layer is needed between GIOP and UDP
  to provide required reliability and mobility
  support
• GIOP Session Protocol (GSP) provides
• reliability,
• fragmentation,
• error detection,
• flow and congestion control,
• resistance to flooding and masquerade attacks.

25
GIOP-UDP mapping
26
GIOP-UDP mapping Design rationale

• Statefull session protocol is needed
• Several session protocol specifications are
  available
• Stream (aka Simple) Control Transmission Protocol
  (SCTP) most prominent
• better alternatives are wellcome
• GIOP Session Protocol follows the design of the
  SCTP
• some differences in fields of protocol messages
• some additional chunk types to support handoffs
  and access recovery
• Nevertheless, the protocols are quite close to
  each other so that a high degree of reuse in
  implementing those two protocols is expected.

27
GIOP Session Protocol - 1

• A modified SCTP
• draft-ietf-sigtran-sctp-09.txt (status IESG last
  call)
• Reliability
• message numbering
• error detection thru Adler-32
• Selective ACKs
• Fragmentation
• WIOP message size should be (at most) MTU

28
GIOP Session Protocol - 2

• Flow/congestion control
• needed to bound GSP control message delays
• needed to bound number of datagrams lost during
  handoffs
• In SCTP TCP-like control mechanism
• In IETF Endpoint Congestion Management WG just
  started Ratebased congestion control
• to be selected in the revised submission

29
GSP Messages - 1

• From SCTP
• INIT, INIT ACK
• Selective Acknowledgement
• Heartbeat Request, Heartbeat ACK
• ABORT
• SHUTDOWN, SHUTDOWN ACK
• Operation Error
• State Cookie, Cookie ACK
• Payload Data

30
GSP Messages - 2

• AccessRequest, AccessRequestACK
• AccessRecoveryRequest, AccessRecoveryRequestACK
• AccessRequestReply, AccessRequestReplyACK
• AccessRecoveryReply, AccessRecoveryReplyACK
• HandoffRequest, HandoffRequestACK
• Synchronize, SynchronizeACK
• Tunneled Data
• Segmented Chunk

31
GSP datagram format
32
GSP Common Header Format
Chunk Field Description
33
INIT Message
34
Access Request Message
35
Segmented Chunk

• to encapsulate a segment of a chunk that does not
  fit into a single GSP datagram
• Most chunks are small, but
• Access Request, Access Reply,
• Access Recovery Request, and
• Access Recovery Request Reply may be quite long
• The receiver must obtain all partial chunks
  before acknowledging the chunk.
• If the beginning chunk (that contains the Chunk
  ID) is missing, all partial chunks MUST be
  silently discarded.
• If middle parts or the end part is missing, the
  receiver MAY use negative acknowledgement if the
  chunk type has the corresponding Acknowledgement
  chunk.

36
GIOP - WAP WTP mapping

• The Wireless Transaction Protocol is designed for
  request/reply applications.
• WTP runs on top of a datagram service, called
  Wireless Datagram Protocol (WDP), and optionally
  it may use a security service, called Wireless
  Transport Layer Security (WTLS).
• If IP is the bearer, then WDP is UDP
• WTP Class 1 transactions provide a reliable
  datagram service
• The reliability provided by WAP WTP Class 1 is
  sufficient for GIOP messaging.
• A GIOP message in the CDR format is transmitted
  in an Invoke PDU or in Segmented Invoke PDUs of
  WAP WTP.
• The SAR functionality is needed for the GIOP-WTP
  mapping

37
Wireless CORBA Extensions

• Location Transparent IOR
• Bootstrapping the terminal
• Initial Acces
• ORB Service Agent
• WAB Interface to Naming Service
• Home Location Register

38
Location Transparent IOR

• One of the mandatory requirements in the RFP was
  to specify mechanisms that hides mobility of
  terminals on which CORBA servers are running from
  CORBA clients
• This can be done by introducing a location
  transparent IOR
• A new IOR component called TAG_MOBILE_IOP
• struct
• version giop_version
• string HLR_host
• unsigned short HLR_port
• sequence ltoctetgt HLR_object_key
• sequence ltoctetgt object_group_id //
  terminal_id
• sequence ltoctetgt object_key // object at
  terminal

39
Object Reference Translation

• When a local object reference is passed from a
  mobile terminal through the Mobile Terminal
  Bridge, it is converted into WIOPIOR format.
• module WIOP
• struct IOR
• string type_id
• sequence ltoctetgt object_group_id
• sequence ltoctetgt object_key
• When a Wireless Access Bridge receives an object
  reference in WIOPIOR format, it converts it
  into IOPIOR format.
• In the profile body the WAB puts its own host,
  port and object_key as well as the TAG_MOBILE_IOP
  component.

40
Updating Object Reference

• If a Wireless Access Bridge gets an invocation to
  an object on a mobile terminal to which it does
  not have an association, then the WAB queries the
  current WAB from the Home Location Register.
• The WAB either
• replies with LOCATION_FORWARD to the requester or
• forwards the invocation to the current WAB.
• If the invocation is forwarded, then the WAB uses
  LOCATION_FORWARD_PERM in the reply.

41
Bootstrapping the terminal - 1/2

• the usual ORB initialization (see Section 4.6-7
  in CORBA V2.3)
• mobile specific initialization
• ObjectIdList list_wireless_access_services ()
• Object resolve_wireless_access_references (
• in ObjectId identifier
• ) raises (InvalidName)
• Initial reference obtained
• MobilityEventSupplier (local reference),
• HomeLocationRegister (IOPIOR), and
• ORBServiceAgent (local reference).

42
Bootstrapping the terminal - 2/2

• the mobile terminal needs to get the
  object_group_id identifying the terminal, and
  which is also known in the home location
  register
• ObjectGroupId resolve_object_group_name (
• in string object_group_name
• ) raises (InvalidName)
• Open Issue Do we need MTB_init similar to
  ORB_init?
• Most probably not!
• Initialization of MTB from an initialization file
  much more simple and robust.

43
Initial Access

• It is not always feasible to maintain
  connectivity all the time.
• MTB provides operations to establish and release
  connectivity
• void connect (
• in ObjectGroupId object_group_id,
• in Object HLR_reference,
• in sequence ltoctetgt location_update_credentials,
• in long timeout
• ) raises (AccessDinied, RequestTimeout)
• void disconnect (
• in ObjectGroupId object_group_id,
• in Object HLR_reference,
• in sequence ltoctetgt location_update_credentials,
• in long timeout
• ) raises (AccessDinied, RequestTimeout)

44
Establishing GIOP Session - 1/3

• Several CORBA applications may simultaneously be
  running
• Only one GIOP Session between the MTB and WAB.
• The GIOP Session is shared by all applications
  running on the terminal.
• The Wireless Access Bridge maintains mapping
  between the object_group_id and UDP endpoint of
  the Mobile Terminal Bridge.

45
Establishing GIOP Session - 2/3
MTB
WAB
HLR
connect
INIT
INIT ACK
COOKIE
ACCESS REQ
COOKIE ACK
ACCESS REQ ACK
update_location
ACCESS REP
ACCESS REP ACK
TerminalHandoffEvent
HandoffArrivalEvent
46
Establishing GIOP Session - 3/3

• If the acknowledgement does not arrive in time,
  then the corresponding message is resent
  according the (implementation dependent)
  retransmission policy.
• The peer MUST interpret duplicate messages as
  lost acknowledgement and re-send the
  corresponding acknowledgment.
• The MTB and WAB MAY use the HEARTBEAT message to
  probe the connectivity.
• The ABORT message MUST be sent, when the initial
  access procedure is terminated.

47
Closing GIOP Session

• When an application invokes the disconnect
  operation
• then if no other application uses the same
  object_group_id
• MTB clears the current WAB information in the
  HLR, which in turn unbinds the names in the
  Naming Service
• the WAB unbinds names from the Naming Service
• WAB generates HandoffDepartureEvent
• If no other application uses the GIOP Session,
• then the MTB sends the SHUTDOWN message to the
  WAB
• which replies with the SHUTDOWN ACK message.

48
ORB Service Agent Interface - 1/3

• void register_object_group (
• in string object_group_name,
• in Object HLR_reference,
• out ObjectGroupId object_group_id,
• out sequenceltoctetgt location_update_credentials,
• in sequenceltoctetgt register_credentials
• ) raises (NameNotUnique, NoAccess,
  AccessViolation)
• void unregister_object_group (
• in ObjectGroupId object_group_id,
• in Object HLR_reference,
• in sequenceltoctetgt register_credentials
• ) raises (UnknownObjectGroupID, NoAccess,
  AccessViolation)

49
ORB Service Agent Interface - 2/3

• ObjectIdList list_visited_domain_services (
• ) raises (NoAccess)
• Object resolve_visited_domain_references (
• in ObjectId identifier
• ) raises(InvalidName)
• ObjectIdList list_home_domain_services (
• ) raises (NoAccess)
• Object resolve_home_domain_references (
• in ObjectId identifier
• ) raises(InvalidName)

50
ORB Service Agent Interface - 3/3

• Interface to Naming Service in Visited and Home
  Domains
• At least the following operations should be
  provided
• ltdomaingt_bind,
• ltdomaingt_resolve,
• ltdomaingt_unbind
• where ltdomaingt is either visited_domain or
  home_domain.

51
WAB Interface to Naming Service

• Used by ORB Service Agent
• void visited_domain_bind (
• in Name n,
• in Object obj
• ) raises (NotFound, CannotProceed, InvalidName,
  AlreadyBound)
• Object visited_domain_resolve (
• in Name n
• ) raises (NotFound, CannotProceed, InvalidName)
• void visited_domain_unbind (
• in Name n
• ) raises (NotFound, CannotProceed, InvalidName)

52
Home Location Register - 1/4

• void update_location (
• in ObjectGroupId object_group_id,
• in string host, // new access bridge
• in unsigned short port,
• in sequenceltoctetgt location_update_credentials,
• ) raises (UnknownObjectGroupID, AccessViolation,
  IllegalTargetBridge)
• void query_location (
• in ObjectGroupId object_group_id,
• out string host,
• out unsigned short port
• ) raises (UnknownObjectGroupID,
  UnknownObjectGroupLocation)

53
Home Location Register - 2/4

• void register_object_group (
• in string object_group_name,
• out ObjectGroupId object_group_id,
• out sequenceltoctetgt location_update_credentials,
• in sequenceltoctetgt register_credentials
• ) raises (NameNotUnique, AccessViolation)
• void unregister_object_group (
• in ObjectGroupId object_group_id,
• in sequenceltoctetgt register_credentials
• ) raises (UnknownObjectGroupID, AccessViolation)

54
Home Location Register - 3/4

• void paging (
• in string object_group_name,
• in long timeout
• ) raises (PagingNotSupported, ObjectGroupNotFound,
  RequestTimeout)
• ObjectIdList list_home_domain_services ()
• Object resolve_home_domain_references (
• in ObjectId identifier
• ) raises(InvalidName)

55
Home Location Register - 4/4

• void home_domain_bind (
• in Name n,
• in Object obj
• ) raises (NotFound, CannotProceed, InvalidName,
  AlreadyBound)
• Object home_domain_resolve (
• in Name n
• ) raises (NotFound, CannotProceed, InvalidName)
• void home_domain_unbind (
• in Name n
• ) raises (NotFound, CannotProceed, InvalidName)

56
Handoff

• Handoff in general
• Network Initiated Handoff
• Terminal Initiated Handoff
• Access Recovery

57
Handoff and Access Recovery - 1/3

• Handoff consists of three distinct phases
• the information gathering phase,
• the decision phase, and
• the execution phase.
• Bridge handoff is a part of the execution phase
  in cases, where the mobile terminal moves from
  one bridging domain to another.
• There are two different cases of handoff
• the backward handoff and
• the forward handoff (access recovery).

58
Handoff and Access Recovery - 2/3

• The backward one is the normal case
• The forward one is performed
• as a location update
• in order to re-establish communication after a
  sudden loss of connectivity.
• In the response we use
• the term handoff to mean the backward handoff and
• the term access recovery.
• The handoff may be network initiated or terminal
  initiated.
• The access recovery is always terminal initiated.

59
Handoff and Access Recovery - 3/3

• Create a new bridge association.
• Transfer the responsibility from the old WAB to
  the new WAB.
• Convert the old bridge association to the
  secondary (tunnelled) status.
• Update Home Location Entries of the object groups
  on the terminal.
• Rebind the entries in the Naming Service in the
  home domain.
• Unbind the names in the Naming Service in the old
  visited domain.
• Bind the names into the Naming Service in the new
  visited domain.
• Generate the corresponding mobility events in the
  terminal domain as well as in the old and new
  visited domains.
• Obtain references to services in the new visited
  domain and mark as staled those in the old
  visited domain.

60
Handoff initiation

• Wireless Access Bridge
• oneway do_handoff(
• in sequenceltoctetgt session_id,
• in Object new_wireless_access_bridge,
• in Object status_callback_target,
• in string status_callback_op_name
• )
• Mobile Terminal Bridge
• oneway propose_handoff(
• in sequenceltoctetgt new_wireless_access_bridge_add
  ress,
• in Object status_callback_target,
• in string status_callback_op_name
• )

61
Network Initiated Handoff - 1/2
old WAB
new WAB
MTB
do_handoff
handoff_request
HANDOFF REQ
Store info Do preparations
HANDOFF ACK
SHUTDOWN
SHUTDOWN ACK
HandoffDepartureEvent
Unbind names from NS
INIT
INIT ACK
COOKIE
62
Network Initiated Handoff - 2/2
new WAB
HLR
MTB
ACCESS REQ
COOKIE ACK
ACCESS REQ ACK
update_location
ACCESS REP
ACCESS REP ACK
rebind names in NS
TerminalHandoffEvent
HandoffArrivalEvent
handoff_completed
bind names to NS
old WAB
63
Handoff methods

• // Called by the old WAB at the new WAB
• void handoff_request(
• in sequenceltoctetgt session_id,
• in SessionState old_wab_state,
• in sequenceltoctetgt old_wab_tunnel, // TCP/IP
  endpoint
• out sequenceltoctetgt new_terminal_access_point
• ) raises (HandoffFailure)
• // Called by the new WAB at the old WAB
• void handoff_completed(
• in sequenceltoctetgt old_session_id,
• in sequenceltoctetgt new_session_id,
• in HandoffStatus status
• )

64
Terminal Initiated Handoff - 1/3

• Optional feature at MTB, must be supported by WAB
• When the propose_handoff operation in the Mobile
  Terminal Bridge is invoked, then the terminal
  starts the terminal initiated handoff procedure.
• The terminal initiated Handoff procedure requires
  that the terminal can establish connectivity to
  the new Wireless Access Bridge before releasing
  the connectivity to the old Wireless Access
  Bridge.
• If this cannot be done, then the terminal
  initiated handoff must be done using the access
  recovery mechanism
• The Mobile Terminal Bridge sends an ABORT message
  to the old WAB and
• then carries out the access recovery to the new
  WAB.

65
Terminal Initiated Handoff - 2/3
new WAB
MTB
propose_handoff
INIT
INIT ACK
COOKIE
ACCESS REQ
COOKIE ACK
ACCESS REQ ACK
HANDOFF REQ
HANDOFF ACK
SHUTDOWN
old WAB
66
Terminal Initiated Handoff - 3/3
old WAB
new WAB
HLR
MTB
SHUTDOWN ACK
handoff_request
Store info
update_location
HandoffDepartureEvent
Unbind names from NS
rebind names in NS
ACCESS REP
ACCESS REP ACK
HandoffArrivalEvent
TerminalHandoffEvent
handoff_completed
bind names to NS
67
Access Recovery - 1/4
MTB
WAB
TerminalDropoutEvent
INIT
INIT ACK
COOKIE
RECOVERY REQ
COOKIE ACK
RECOVERY ACK
68
Access Recovery - 2/4
MTB
old WAB
SYNC
SYNC ACK
SYNC
SYNC ACK
Missing data and acknowledgements
AccessRecoveryEvent if AccessDropoutEvent
delivered
TerminalRecoveryEvent
69
Access Recovery - 3/4
new WAB
old WAB
HLR
MTB
recovery_request
Store info
update_location
RECOVERY REP
rebind names in NS
RECOVERY ACK
SYNC
SYNC ACK
SYNC
SYNC
SYNC ACK
SYNC ACK
Missing data and acknowledgements
Missing data and acknowledgements
70
Access Recovery - 4/4
new WAB
old WAB
MTB
recovery_completed
HandoffDeparturelEvent
Unbind names from NS
TerminalHandoffEvent
HandoffArrivalEvent
bind names to NS
71
Access Recovery Methods

• // Called by the new WAB at the old WAB
• void recovery_request(
• in sequenceltoctetgt session_id,
• out SessionState old_wab_state,
• out sequenceltoctetgt old_wab_tunnel // TCP/IP
  endpoint
• out sequenceltoctetgt new_terminal_access_point
• ) raises (HandoffFailure)
• // Called by the new WAB at the old WAB
• void recovery_completed(
• in sequenceltoctetgt old_session_id,
• out sequenceltoctetgt new_session_id,
• in HandoffStatus status
• )

72
Issues to be discussed

• Use of Notification Service
• Use of Interoperable Naming Service
• Use of Messaging Service
• Use of generic ORB Services

73
Mobility Events - 1/3
74
Mobility Events - 2/3

• module Mobility
• struct TerminalHandoffEvent
• DomainId new_visited_domain
• struct HandoffDepartureEvent
• TerminalName moving_terminal
• DomainId new_visited_domain
• struct HandoffArrivalEvent
• TerminalName moving_terminal
• DomainId old_visited_domain

75
Mobility Events - 3/3

• struct TerminalDropoutEvent
• struct TerminalRecoveryEvent
• struct AccessDropoutEvent
• TerminalName dropped_terminal
• struct AccessRecoveryEvent
• TerminalName dropped_terminal

76
Use of Interoperable Naming Service - 1/2

• This specification does not affect the
  specification of Interoperable Naming Service.
• The ORB Service Agent provides operations so that
  the applications on a mobile terminal need only
  once bind a name into the Naming Service in a
  visited domain.
• The ORB Service Agent together with the Wireless
  Access Bridge moves the name bindings from the
  Naming Service in the old visited domain to that
  in the new visited domain during the handoff
  procedure.
• The WAB also takes care that entries in the
  Naming Service are removed if the terminal
  disappears and does not re-appear in an
  implementation depend time-interval.

77
Use of Interoperable Naming Service - 2/2

• The object references, the names of which are
  bound into the Naming Service in the home domain
  through the ORB Service Agent, are automatically
  updated during the handoff procedure.
• Naming Conventions
• recommendation
• mobile_terminal/lthome_domain_namegt/ltterminal_namegt
  /ltobject_namegt

78
Use of Messaging Service

• This proposal does not give any specific uses for
  Messaging Service, nor is use of Messaging
  Service in any way affected by the proposed
  technology.
• However, it is possible to reduce the amount of
  messages sent with Messaging Service somewhat
  with a simple optimization.
• Since the Wireless Access Bridges used by the
  mobile terminal are better informed on the
  terminal's whereabouts and connectivity,
• it would be beneficial to implement Messaging
  Router functionality in the WAB.

79
Use of other ORB Services

• The mobile terminal will also need to access
  CORBAservices in other ORB domains.
• ORB Service Agent is provided for use by the
  mobile terminal.
• The ORB Service Agent provides facilities for the
  mobile terminal to query and access available
  services in both the visited domain and the
  terminal's home domain.
• In case of handoff, the ORB Service Agent
  automatically receives services available in the
  new visited domain.
• However, an application need to resolve object
  references.

80
Generic Invitation Service - 1/2

• Although not requested in the RFP, this proposal
  specifies a generic invitation server.
• Its objective is to provide an interface that
  allows objects in other domains to contact the
  terminal.
• It is recommended that this interface is bound to
  the Naming Service in the visited and home
  domains.
• When an application wants to contact an
  application on the mobile terminal, then it
  invokes the invite operation.

81
Generic Invitation Service - 2/2

• enum InvitationStatus
• INVITATION_ACCEPTED, INVITATION_REJECTED
• interface InvitationServer
• void invite(
• in string invating_party, // name of user
• in string invating_application, // name of
  application
• out InivitationStatus status,
• out string reply_message,
• out Object peer_object)

82
Homeless Terminals
83
Homeless Terminals

• A "homeless terminal" is a terminal that does not
  have a home domain and hence an entry in a Home
  Location Register.
• In the current specification the Home Location
  Register provides the means for a domain to
  authenticate the visiting terminal
• If the terminal does not have an HLR entry, then
  it is impossible to do ORB-level authentication
  before the Wireless Access Bridge accepts the
  establishment of a GIOP Session.
• A "homeless terminal" MUST use NIL as its HLR
  reference.
• A Wireless Access Bridge MAY reject an access
  request with NIL as the HLR reference.

84
Conformance Points

• Wireless Access
• Terminal Mob ility
• Optional features

85
Wireless Access Conformance Point

• Initial access,
• access recovery, and
• either GIOP/UDP mapping
• a subset of GIOP Session Protocol
• or GIOP/WAP WTP mapping.

86
Terminal Mobility Conformance Point - 1/4

• In the terminal domain
• - terminal bootstrap,
• - initial access,
• - access recovery,
• - network initiated handoff,
• - ORB Service Agent interface,
• - mobility events, and
• - GIOP/UDP mapping.

87
Terminal Mobility Conformance Point - 2/4

• In the visited domain
• - Initial access,
• - access recovery,
• - network initiated handoff,
• - terminal initiated handoff,
• - support of ORB Service Agent, and
• - GIOP/UDP mapping.

88
Terminal Mobility Conformance Point - 3/4

• In the home domain
• - Home Location Register interface.
• - Obs. HLR must implement the paging function.
• If a paging is not supported, then the paging
  operation MUST raise the exception
  PagingNotSupported.

89
Terminal Mobility Conformance Point - 4/4

• Optional features include
• - Terminal initiated handoff in the terminal
  domain,
• - GIOP-WTP mapping in the terminal and visited
  domains,
• - mobility events in the visited domain, and
• - support of "homeless" terminals in the visited
  domain.

90
Conclusions
91
Conclusions

• Architectural design complete, mature and
  validated
• DOLMEN experience reused
• Interface design complete
• only minor modifications expected
• Functional design almost complete
• some details need to be verified
• GIOP mappings
• UDP mapping initial proposal based on SCTP,
  alternatives possible
• WAP WTP mapping to be completed but
  straightforward

92
Thank you for your attention