System and method for determining whether a network destination is reachable

• US 20050122910A1
• Filed: 01/06/2005
• Published: 06/09/2005
• Est. Priority Date: 02/23/1999
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Parupudi, Gopal, Goertzel, Mario C., Srinivas, Murthy
• Granted Patent: US 7,680,924 B2
• Time in Patent Office: Days
• US Class Current: 370/241
• CPC Class Codes: G06F 2209/544 Remote
• CPC Class Codes: G06F 9/542 Event management; Broadcasting; Multicasting; Notifications
• CPC Class Codes: H04L 41/0604 using filtering, e.g. reduction of information by using priority, element types, position or time
• CPC Class Codes: H04L 43/0811 by checking connectivity

Abstract

A method and system for providing system event notifications to clients such as applications. Clients register for notification of one or more types of events with a registration mechanism, and a System Event Notification Service, (SENS), receives system event information and fires event notifications in response thereto. A distribution mechanism selectively communicates the fired event to each client registered for notification thereof based on the type of event. Events include network events, for which the service monitors the connectivity state of the machine, including whether a connection is established or lost, the type of connection (LAN/WAN) and bandwidth information. To monitor a LAN state, the service caches outgoing and incoming network information including errors and packet counts and statistically evaluates this cached information against current information to determine whether the connection is established or lost. The service also determines if a destination (IP address or name) is reachable, by periodically polling destinations. Other system event notifications may be fired, including logon or logoff operations and power management events.

Claims

1. A system for providing notifications of computer system events to clients, comprising:

a central service for receiving system events and for firing event notifications in response thereto, wherein the central service includes a mechanism for determining whether a network destination is reachable;

a registration mechanism for clients to register for notification of one or more types of events;

a distribution mechanism for communicating a fired event notification to each client registered for notification thereof based on the type of event notification.

2. The system of claim 1 wherein the mechanism for determining whether a network destination is reachable is associated with a list of network destinations.

3. The system of claim 2 wherein the mechanism for determining whether a network destination is reachable regularly polls each destination in the list to make a determination as to the reachability thereof.

4. The system of claim 1 wherein the mechanism for determining whether a network destination is reachable determines that a destination is not reachable if the name of the destination is not resolvable into an Internet protocol address.

5. The system of claim 1 wherein the mechanism for determining whether a network destination is reachable determines that a destination is reachable if the Internet protocol address of the destination corresponds to a local subnet.

6. One or more computer-readable media having executable instructions stored thereon that, when executed, implement the following steps:

receiving system information at a central service;

determining whether a network destination is reachable;

publishing an event notification in response thereto, the event notification having an event type associated therewith;

receiving the event notification at a loosely coupled events database;

matching the event notification with at least one client that has subscribed for event notification based on the type of event; and

communicating the event notification to each client that has subscribed therefor.

7. The one or more computer-readable media of claim 6 wherein the central service publishes an event when the network destination changes from reachable to unreachable.

8. The one or more computer-readable media of claim 6 wherein the central service publishes an event when the network destination changes from unreachable to reachable.

9. The one or more computer-readable media of claim 6 wherein determining whether the network destination is reachable further comprises pinging the destination.

10. The one or more computer-readable media of claim 6 wherein determining whether the network destination is reachable further comprises periodically pinging the destination.

11. The one or more computer-readable media of claim 6 wherein determining whether the network destination is reachable further comprises evaluating whether the name of the destination is resolvable into an Internet protocol address.

12. The one or more computer-readable media of claim 6 wherein determining whether the network destination is reachable further comprises evaluating whether the Internet protocol address of the destination corresponds to a local subnet.

13. A method, comprising:

determining if a name of a network destination is in the form of an Internet protocol address;

if the name of the network destination is not in the form of an Internet protocol address, attempting to resolve the name of the network destination to an Internet protocol address;

if the name of the network destination is provided as an Internet protocol address or can be resolved to an Internet protocol address and if the resulting Internet protocol address is not in a local subnet, pinging the network destination represented by the Internet protocol address to determine if the network destination is reachable; and

selectively outputting whether the network destination was reachable.

14. The method of claim 13 wherein pinging the network destination further comprises using a cache that contains the results of previous ping attempts to the same network destination.

15. The method of claim 14 wherein the cache that contains the results of previous ping attempts may also be updated from one or more other processes.

16. The method of claim 13 wherein selectively outputting whether the network destination is reachable further comprises firing an event when the state of network destination reachability has changed from a previous value.

17. The method of claim 13 wherein selectively outputting whether the network destination is reachable further comprises returning whether the network destination was reachable as a result in response to a call from a client.