Distance-aware service discovery mechanism for determining the availability of remote services in wireless personal area networks

• US 20050021725A1
• Filed: 06/28/2004
• Published: 01/27/2005
• Est. Priority Date: 06/30/2003
• Status: Active Grant

• Current Assignee: Sony Deutschland GmbH (Sony Group Corp.)
• Original Assignee: Sony Deutschland GmbH (Sony Group Corp.)
• Inventors: Lobbert, Johannes
• Granted Patent: US 8,060,590 B2
• Time in Patent Office: Days
• US Class Current: 709/223
• CPC Class Codes: H04L 67/04 specially adapted for terminals or networks with limited capabilities; specially adapted for terminal portability
• CPC Class Codes: H04L 67/51 Discovery or management thereof, e.g. service location protocol [SLP] or web services
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04W 40/24 Connectivity information management, e.g. connectivity discovery or connectivity update
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

The present invention refers to a method for extending replicated service discovery information for determining the availability of requested remote services in a client/server-based network environment (400), wherein each of a multiplicity of client terminals (402) is connected to a single file and/or application server (404, 405) of a specific service provider via a wireless multi-hop network which is based on a store-and-forward messaging principle, i.e. a wireless Personal Area Network (PAN) based on Bluetooth technology. Thereby, said service discovery information is needed for a selection of the optimal service provider. The method comprises the steps of providing (S1) network distance information indicating the number of intermediate network nodes (406) acting as forwarding servers for accessing remotely accessible services between a client terminal (402) and a number of file and/or application servers (404, 405) within said wireless wireless multi-hop network and selecting (S2) a requested remote service running on a file and/or application server (404) of a specific service provider at a network distance in the physical proximity of the respective client terminal (402) which can be reached from said client terminal (402) with a minimum of forwarding delay based on said network distance information.

According to one embodiment of the invention, service discovery information is dynamically adapted (S3) to information concerning varying resource availability and/or changing link characteristics within said wireless multi-hop network. In this connection, cached service discovery information is marked as active (S3a) only as long as a file and/or application server (404, 405) participates in a wireless communication session with the respective client terminal (402) and marked as inactive (S3b) after the connection between said server (404, 405) and the respective client terminal (402) is closed and a predefined time-out period has expired, thereby discarding (S3c) outdated service discovery information. According to a further embodiment, information indicating the usage of requested remote services is taken into account during the process of selecting (S2) a specific remote service.

Claims

1. A method for transmitting service discovery information for determining the availability of requested services in a client/server-based network (400), wherein each of a multiplicity of client terminals (402) is connected to a file and/or application server (404, 405) via a wireless network,

comprising the step of

transmitting (S1) distance information indicating the number of available intermediate network nodes (406) acting as proxy forwarding servers for accessing remotely accessible services between a client terminal (402) and a number of file and/or application servers (404, 405) within said wireless wireless multi-hop network.

2. A method according to claim 1,

wherein

the service discovery information, including the distance information, is dynamically adapted (S3) to information concerning varying resource availability and/or changing link characteristics within said wireless multi-hop network.

3. A method according to claim 2,

characterized in that

cached service discovery information is marked as active (S3a) only as long as a file and/or application server (404, 405) participates in a wireless communication session with the respective client terminal (402) and marked as inactive (S3b) after the connection between said server (404, 405) and the respective client terminal (402) is closed, and a predefined time-out period has expired, thereby discarding (S3c) outdated service discovery information.

4. A method according to claim 1,

characterized in that

information indicating the usage of requested remote services is taken into account during the process of selecting (S2) a specific remote service.

5. A method according to claim 1, wherein client terminals (402) are connected to file and/or application servers (404, 405) of a number of service providers via a Bluetooth-enabled Personal Area Network (PAN) and communication between said client terminals (402) and servers (404, 405) is based on an application-layer protocol such as the Bluetooth Service Discovery Protocol (SDP),

characterized in that

in case a client terminal (402) which does not implement a method according to anyone of the preceding claims queries SDP records of a file and/or application server (404 or 405) within said Bluetooth-enabled Personal Area Network, only locally reachable services are returned.

6. A method according to claim 1, wherein peers (302) are provided with service discovery information replicated to multiple peers (304, 305) in the peer-to-peer environment of a Bluetooth-enabled Personal Area Network (PAN), said peers (302, 304, 305) communicating with each other via the Bluetooth Service Discovery Protocol (SDP), wherein a first peer (302) is connected to a second peer (304) over a first wireless link and said second peer (304) is connected to a third peer (305) over a second wireless link, thereby using the Bluetooth Logical Link Control and Adaptation Protocol (L2CAP) as a data-link-layer protocol,

said method being characterized by said second peer (304) conducting the following steps:

performing a Bluetooth inquiry (S4) to detect active Bluetooth nodes (305) in its radio range, thereby acting as an SDP client,

selecting (S5a) a third peer (305), which acts as an SDP server for the second peer (304), and opening a first L2CAP channel on a well-known protocol/service multiplexer (PSM1),

sending (S6) SDP messages to the third peer (305) to check the availability of services offered by the third peer (305) as well as configuration information for known services or browse the service database (305a) on the third peer (305), and

establishing (S7a) a Bluetooth PAN link to use services offered by the third peer (305) and adding (S7b) services from the service database (305a) of said third peer (305) to its local database (304a),

and thereafter said first second peer (302) conducting the following steps;

performing a Bluetooth inquiry (S8) to detect active Bluetooth nodes (304) in its radio range, thereby acting as an SDP client,

selecting (S9a) said second peer (304), which then acts as an SDP server for said first peer (302), and opening (S9b) a second L2CAP channel on a further well-known protocol/service multiplexer (PSM2), and

detecting (S10) all available services offered by said second (304) and said third peer (305) via SDP.

7. A method for processing information transmitted according to claim 1,

comprising the step of:

based on said received distance information, selecting (S2) a remote service running on a file and/or application server (404) of a specific service provider at a network distance in the physical proximity of the respective client terminal (402) which can be reached from said client terminal (402) with a minimum of forwarding delay.

11. An intermediate network node serving as a proxy forwarding server for accessing remotely accessible services in a client/server-based network environment (400), said network node (406) being wirelessly connected to a client terminal (402) and different file and/or application servers (404, 405) of a number of service providers via a wireless multi-hop network based on a store-and-forward messaging principle,

characterized by

a service discovery manager unit (SDM) implementing a method according to claim 1 for determining the availability of requested remote services in said client/server system (400).

8. A wireless service discovery information signal enabling the receiver to determine the availability of requested services in a client/server-based network (400), wherein each of a multiplicity of client terminals (402) is connected to a file and/or application server (404, 405) via a wireless network,

the signal comprising distance information indicating the number of available intermediate network nodes (406) acting as proxy forwarding servers for accessing remotely accessible services between a client terminal (402) and a number of file and/or application servers (404, 405) within said wireless wireless network.

9. A wireless communication device, comprising

means for receiving and processing a signal according to claim 8, and

means for selecting (S2) a remote service running on a file and/or application server (404) of a specific service provider at a network distance in the physical proximity of the respective client terminal (402) which can be reached from said client terminal (402) with a minimum of forwarding delay based on said distance information.

10. A data base of a service discovery message for wirelessly exchanging service discovery information between a number of peers in the peer-to-peer environment of a Bluetooth-enabled Personal Area Network (PAN) by using the Bluetooth Service Discovery Protocol (SDP), said data record comprising fields for the addresses of service providers offering a requested remote service and optional service-specific SDP values,

characterized by

a data field that contains an entry indicating the number of intermediate nodes (406) between a peer (404) acting as an SDP proxy server for the client terminal (402) of a service user and network nodes (405) providing a remote service requested by said service user.