METHOD FOR OPERATING A GATEWAY

Abstract

A gateway, operable in a hierarchical heterogeneous network, includes at least two interfaces of which at least one is connectable to a lower network level, and the communication protocols in the network provide a message for offering a service and a message for searching for a service, receipt of a message coming in from a lower network level in the gateway at an interface for offering a service, and/or an item of information identifying the offered service, is noted in the interface receiving this message or in a management unit assigned thereto, and receipt of a message from a lower network level in the gateway at an interface for searching for a service and/or an item of information identifying the sought service is noted in the interface or management unit, and if the messages relate to the same service, a message for the service availability is sent via the interface.

Claims

1. A method for operating a gateway in a hierarchical heterogeneous network, the gateway including at least two interfaces, of which at least one interface is connectable to a lower network level, the method comprising: providing, via the protocols provided in the network for communication, a message for offering a service and a message for searching for a service; noting a receipt of a message coming in from a lower network level in the gateway at an interface for offering a service, and/or an item of information identifying the offered service, in the interface receiving the message or in a management unit assigned to the interface; and noting a receipt of a message coming in from a lower network level in the gateway at an interface for searching for a service, and/or an item of information identifying the sought service, in the interface receiving the message or in a management unit assigned to the interface; and sending, if the message for offering a service and the message for searching for a service relate to the same service, a message relating to the availability of the service, via the interface at which the message for searching for the service was received.

2. The method of claim 1, wherein at least one interface is connectable to a higher network level, and at least one interface is connectable to a lower network level, and the message coming in from a lower network level in the gateway at an interface for offering a service is forwarded to at least one higher network level, and the message coming in from a lower network level in the gateway at an interface for searching for a service is forwarded to a higher network level at least when the sought service does not agree with the offered service or the offered services.

3. The message of claim 1, wherein in addition to the noting of the receipt of a message and searching for and/or offering a service, or an item of information identifying this service, the address of the node sending the message is noted in the interface or in a management unit assigned to this interface.

4. The method of claim 1, wherein the notes in the interfaces or in the management unit assigned to the respective interface concerning the receipt of a message for searching for and/or offering a service are provided with a temporal validity.

5. The method of claim 3, wherein the message for searching for and/or offering a service is sent repeatedly by the respective origin node at regular intervals.

6. The method of claim 1, wherein if the message for offering a service and the message for searching for a service relate to the same service, the message for searching for this service is not forwarded to a higher network level.

7. The method of claim 1, wherein messages for searching for and/or offering a service contain an item of information on the basis of which it is selected to which region of the overall network this message is forwarded.

8. The method of claim 1, wherein if the message for searching for a service and the message for offering a service relate to the same service, the message relating to the availability of this service is sent as a multicast, broadcast, or unicast via the interface at which the message for searching for the service was received.

9. The method of claim 1, wherein FIND messages and/or OFFER messages received within a specifiable time interval are collected and are then forwarded within a common message.

10. A gateway in a hierarchical heterogeneous network, comprising: a gateway arrangement including at least two interfaces, of which at least one interface is connectable to a lower network level, the gateway being configured to perform the following: providing, via the protocols provided in the network for communication, a message for offering a service and a message for searching for a service; noting a receipt of an OFFER message coming in from a lower network level in the gateway at an interface for offering a service, and/or an item of information identifying the offered service, in the interface receiving the OFFER message or in a management unit assigned to the interface; and noting a receipt of a FIND message coming in from a lower network level in the gateway at an interface for searching for a service, and/or an item of information identifying the sought service, in the interface receiving the FIND message or in a management unit assigned to the interface; and sending, if the OFFER message for offering a service and the FIND message for searching for a service relate to the same service, a message relating to the availability of the service, via the interface at which the message for searching for the service was received.

11. A computer readable medium having a computer program stored on a gateway in a hierarchical heterogeneous network, which is executable by a processor, comprising: a program code arrangement having program code for operating a gateway in a hierarchical heterogeneous network, the gateway including at least two interfaces, of which at least one interface is connectable to a lower network level, by performing the following: providing, via the protocols provided in the network for communication, a message for offering a service and a message for searching for a service; noting a receipt of a message coming in from a lower network level in the gateway at an interface for offering a service, and/or an item of information identifying the offered service, in the interface receiving the message or in a management unit assigned to the interface; and noting a receipt of a message coming in from a lower network level in the gateway at an interface for searching for a service, and/or an item of information identifying the sought service, in the interface receiving the message or in a management unit assigned to the interface; and sending, if the message for offering a service and the message for searching for a service relate to the same service, a message relating to the availability of the service, via the interface at which the message for searching for the service was received.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 shows a block diagram representing a segment of a hierarchical network in which a provider has sent an OFFER message.

[0017] FIG. 2 shows a block diagram of a segment of a hierarchical network in which a FIND message has been sent.

[0018] FIG. 3 shows a block diagram of a segment of a hierarchical network in which a FIND response message or an OFFER message has been sent in response to a FIND message.

[0019] FIG. 4 shows a flow diagram with possible method steps in the processing of an OFFER message.

[0020] FIG. 5 shows a flow diagram with possible method steps in the processing of a FIND message.

DETAILED DESCRIPTION

[0021] FIG. 1 schematically shows a segment of a hierarchical heterogeneous network 1 in which nodes 2, 3, 4, and 5 are shown as examples. Nodes 2 and 4 are connected to a gateway 10 via a subnetwork 6, and nodes 3 and 5 are connected to a gateway 20 via a subnetwork 7, for example a bus system. Gateway 10 is connected to a gateway 30 via a subnetwork 8, and gateway 20 is also connected to gateway 30 via a subnetwork 9. In gateway 10, there is fashioned an interface 11 that is connected to subnetwork 6, which realizes a lower network level. A further interface 12 of gateway 10 is connected to a higher network level 8. Gateway 20 is fashioned analogously to gateway 10. An interface 21 is connected to subnetwork 7, which is a lower network level, and an interface 22 is connected to subnetwork 9, which is a higher network level.

[0022] In gateway 30 there are fashioned two interfaces 31 and 32 connected to subnetworks 8 or 9. Here, subnetworks 8 and 9 form a lower network level relative to a subnetwork 40 that is connected to an interface 33 of gateway 30.

[0023] In FIG. 1, path 41 of an OFFER message, sent by the provider of a particular service, is shown by a dashed arrow. The OFFER message is conducted from node 2 via the subnetwork or bus system 6 to interface 11 of gateway 10. This takes place for example in the form of a multicast or broadcast message. If gateway 10 receives this OFFER message, it notes the availability of the offered service at interface 11 at which the message was received, in the form of a corresponding note 13 in the interface, or in a management unit assigned to this interface. The management unit may be configured in the gateway and manages the entries or notes of all interfaces of this gateway. Analogously, a management unit can also be provided for the other gateways. Note 13 can also contain, alongside the designation of the interface at which the OFFER message was received, the concrete address of node 2 from which the OFFER message was sent in subnetwork 6.

[0024] The OFFER message received at interface 11 is forwarded in gateway 10 to interface 12 that is connected to subnetwork 8, subnetwork 8 being a higher network level than subnetwork 6. From interface 12, the OFFER message is forwarded to interface 31 of gateway 30 and, corresponding to note 13, a note 34 is stored in a region of interface 31 or in a management unit assigned to this interface. Because subnetwork 40 realizes a higher network level relative to subnetwork 8, the OFFER message inside gateway 30 is forwarded to subnetwork 40 via interface 33. If additional gateways are present there, then the OFFER message is also forwarded in these gateways from the respectively lower network level to the respectively higher network level.

[0025] FIG. 2 shows a possible path 42 of a FIND message. The FIND message is sent from node 3 via subnetwork 7, for example as a multicast or broadcast, and thus indicates that node 3 is looking for a service. The FIND message is forwarded to gateway 20. In interface 21, connected to subnetwork 7, of gateway 20, a note 23 is entered that indicates the receipt of FIND message 42. This note marks the need for the service sought with the FIND message at interface 21. In addition to the information that interface 21 identifies, the concrete address of the requesting node 3 from subnetwork 7 can also be stored in note 23.

[0026] In accordance with the rule that FIND messages from a lower network level are forwarded inside a gateway to the higher network levels, the FIND message is forwarded from interface 21 in gateway 20 to interface 22, which is connected to subnetwork 9, because subnetwork 9 is a higher network level relative to subnetwork 7. Via subnetwork 9, the FIND message reaches interface 32 of gateway 30. In interface 32, or in a management unit assigned to this interface 32, a note concerning the receipt of the FIND message is stored, analogously to interface 21. Inside gateway 30, the FIND message is forwarded to interface 33, which is connected to subnetwork 40, which is a higher network level relative to subnetwork 9.

[0027] FIG. 3 is based on the assumption that an OFFER message and a FIND message, as described in FIGS. 1 and 2, have been sent and the corresponding notes have been stored in the interfaces or in corresponding management units. Through comparison of the entries in the interfaces, or in the management unit assigned to the interfaces, it is now determined that the presence of an OFFER message has been noted, which corresponds to the receipt of the FIND message at interface 32. For this reason, via interface 32 a message corresponding to the received OFFER message is transmitted to subnetwork 9. The path of this message is shown in FIG. 3 as a dashed arrow and is designated with reference character 43.

[0028] The message arrives at gateway 20. There, in interface 22 or in a management unit assigned to this interface, a note 24 is stored that represents the receipt of this message. Because the need for the service offer contained in the message is contained in interface 22 of gateway 20, the message is then forwarded inside gateway 20 from interface 22 to interface 21, and from there is sent via subnetwork 7, so that this message reaches node 3. The message can be fashioned as an OFFER message, but can also be fashioned as a specific FIND response message.

[0029] According to the sequences shown in FIGS. 1 through 3, in all gateways between nodes 2 and 3, notes, or entries concerning availability, are stored that represent the service. These can be used to convey requests or messages for the subscription to the service from node 3 to node 2. These notes or entries can also be used or expanded in order to convey the data packets sent after the service discovery and the subscription.

[0030] If requesting node 3 first becomes active, and then offering node 2 becomes active, corresponding search requests are present already before the appearance of the provider at the gateways. As soon as the provider sends the first OFFER message, these entries trigger a forwarding to the requester (node 3).

[0031] The OFFER messages may be sent from higher to lower network levels only as a response to concrete requests, thus avoiding unnecessary messages to the respectively lower network levels. FIND messages are sent only through the subnetworks that have to be passed through in order to find a particular service, and also later for the data transport.

[0032] FIG. 4 shows method steps that can run in a gateway in order to process an incoming OFFER message. In a step 100, it is checked whether an OFFER message was received at an interface that belongs to a lower network level. If this is the case, then in a step 101 this OFFER message is forwarded to the interface or interfaces that are connected to a higher network level. In step 102, it is checked whether an availability of the service offered by the received OFFER message is already noted on this gateway. If this is the case, the note, or entry concerning availability, is updated in the corresponding interface. If this service is not yet available on the gateway, i.e. no note exists that identifies this service as available, then in a step 103 a corresponding note is placed in the interface at which the OFFER message was received.

[0033] In a step 104, it is checked whether FIND messages, i.e. outstanding search requests for the service corresponding to the received OFFER message, are present at other interfaces. If this is the case, then in a step 105 a FIND response message or an OFFER message is forwarded to the corresponding interfaces that identify path 42 of the FIND messages.

[0034] FIG. 5 shows possible method steps in the processing of a FIND message in a gateway. In step 200, it is assumed that a FIND message has been received at an interface of the relevant gateway. A note is then entered or updated.

[0035] In a step 201, it is checked whether there exist, at other interfaces, OFFER messages matching this FIND message, i.e. whether, at another interface, a note is already stored that indicates the availability of the requested service. If this is the case, then an OFFER message or a FIND response message is sent to the interface at which the FIND message was received in step 200. Otherwise, in a step 203 it is checked whether the FIND message was received by an interface that realizes a lower network level inside the gateway. Only if this is the case, then in a step 204 this FIND message is forwarded to the interfaces of the gateways that are assigned to a higher network level.

[0036] Of course, further specific embodiments are possible that develop the specific embodiments shown as examples in FIGS. 1 through 5. For example, the notes, or availability entries and search entries, can be provided with a temporal validity. This permits dynamic modification in the network topology. The provider of a service, as well as possible subscribers or requesters of a service, can use cyclically sent OFFER messages and FIND messages to communicate the offers or their need. If these messages are not present, then the corresponding notes, or availability and request entries, are deleted in the interfaces of the gateways after the next time interval. Relevant nodes that have subscribed to a service can be informed if a service is no longer offered.

[0037] According to a further possible specific embodiment, a FIND message that relates to a corresponding availability entry in a gateway is no longer forwarded; rather, a FIND response message, or an OFFER message, is merely sent to the requesting node. Alternatively, in the case of agreement of a FIND message with an OFFER message, the FIND message can nonetheless be forwarded. In some circumstances this makes it possible to find alternative paths, or to update the availability entries.

[0038] It is also conceivable, according to alternative strategies, to forward FIND messages and OFFER messages upon receipt at an interface that is assigned to a higher network level. In this way, for example additional paths can be found, or particular network topologies can be supported. Corresponding strategies for avoiding routing loops are then however necessary.

[0039] In addition, it is conceivable to configure FIND messages and OFFER messages for example through a corresponding header field in such a way that it is possible to limit the region of the network in which a service is offered or within which a service is sought. It is conceivable that a service be offered only in a subnetwork in which the provider is actually present. A gateway configured in this way would then not forward the OFFER message. This achieves the result that in subnetworks in which particular services are not required, these services are also not offered.

[0040] According to a further possible specific embodiment, it can be provided that a FIND response message or an OFFER message sent after the matching of a search entry with an availability entry is sent as a multicast, broadcast, or unicast. In the case of a unicast, the service would then be offered precisely to the node that initiated the search request or FIND message.

[0041] In order to save additional bandwidth, it can be provided that a gateway carries out the forwarding of FIND messages and OFFER messages only after expiration of a specified time interval. In this way, a plurality of different FIND messages and OFFER messages can be sent in a common message, and the overhead of protocol layers situated thereunder can be reduced. The same information can also be prevented from being sent multiple times in a particular time interval.

[0042] In addition, in principle more instances of a service can be present in a network. Using a FIND message, it is then possible to search for a particular instance, or for all available instances, of a service. If all available instances are sought, FIND messages are generally forwarded in order to find all instances in the network. Thus, such a FIND message can be followed by a plurality of OFFER messages for various instances. As already mentioned, instead of sending an OFFER message in case of an agreement with a FIND message, it is also possible to send a FIND response message that represents a particular message type that specifically describes the situation of agreement of a search request with a service offer. Thus, a distinction in the processing of OFFER messages is possible that are forwarded upward in the network hierarchy and the responses to search requests when agreement has taken place, that are sent to lower levels as needed. In this way, a simpler realization of the method, and in particular a simplified realization of the requests inside the gateway, is enabled.

[0043] Of course, the developments named above can be combined with one another.