WO1997035258A1

WO1997035258A1 - Network match maker for selecting clients based on attributes of servers and communication links

Info

Publication number: WO1997035258A1
Application number: PCT/US1997/004716
Authority: WO
Inventors: Daniel Joseph Samuel; Jeffrey Jackiel Rothschild; Stephen M. Grimm; Michael A. Wolf
Original assignee: Mpath Interactive, Inc.
Priority date: 1996-03-21
Filing date: 1997-03-20
Publication date: 1997-09-25
Also published as: JP2000508097A; US5828843A; EP0965084A1; US20020091833A1; US5894556A; US6345297B1; AU2343097A; US6128660A

Abstract

A network matching method for creating matched sets of users of a multi-user network application. Each user is associated with a client program (CL1) of a client computer connected to the network. The clients are selected into matched sets based on attributes of their users, the clients, servers, and/or communication links. The network match maker server program (MM) works with three different forms of network applications: peer-to-peer, multiple clients to a single server and multiple clients to multiple servers.

Description

NETWORK MATCH MAKER FOR SELECTING CLIENTS BASED ON ATTRIBUTES OF SERVERS AND COMMUNICATION LINKS CROSS-REFERENCE TO RELATED PROVISIONAL APPLICATION

This patent application claims the benefit of U.S Provisional Application No 60/013,812, filed on March 21, 1996

BACKGROUND OF THE INVENTION Computer networks are widely used to connect multiple computer systems together for communicating and sharing information. Computer networks can also be used to implement multi-user applications that allow multiple users to share in the operation of a computer program. Common examples are video and teleconferencing applications, online multiplayer games which allow multiple users to play a game with one another and online chat environments. A problem common to all such multi-user network applications is providing an efficient way to bring together groups of users to join in the running of a multi-user application. Today, the known solutions deal only with the users requirements such as which other people they wish to be matched with. These solutions provide little more than manual methods for the users to select the other users that they wish to be matched with. This is workable only when there are reasonable numbers of users in the pool of all users. It becomes unworkable when there are large numbers of users and when the application has special requirements for network performance or capabilities of the client and/or server computer systems used to implement the application.

Networked applications for multiple clients exist in three forms. Peer-to- peer applications are executed by multiple client computers with no server or servers required. All communication traffic during the execution of the application is directed between the clients. Other multiple client networked applications use a single server system. The server may execute some portion of the application that is to be shared by all of the clients while the remainder of the application is executed on the clients. The server can also act as a communications collection point Some or all of the communication traffic is between each of the clients and the server The clients may additionally communicate with one another as needed Finally, multiple servers may be used in a multiple client application Similar to the case of a single server, a portion of the application may be executed on the servers The multiple servers can also provide communications collection points for the clients

SUMMARY OF THE INVENTION

In the present invention, a network match making system is used to create matched sets of users of a multi-user networked application. Each user is associated with a client computer connected to a network Also on the network is a server computer which executes a software process that is the network match maker In some implementations there are one or more additional servers that are also used for supporting the networked application The clients are selected into matched sets based on attributes of their users, the clients, application class and instance, the attributes of the servers and the properties of the client-to-client and client-to-server communications links The network match maker works with three forms of network application implementation peer-to-peer, multiple clients to a single server and multiple clients to multiple servers

The present invention presents a network match making system that solves the above described problems in the prior art and provides an automated means for users to be matched with one another for a networked application The network match maker not only takes into account the users preferences and attributes, but the attributes of the client computer, the application, any optional servers needed by the application and the properties of the communications links between the clients and the clients and any optional servers

These and other features and advantages of the present invention will become apparent from the following detailed description of the invention and accompanying drawings

BRIEF DESCRIPTION OF THE DRAWINGS

Fig 1 is a flow chart showing the interaction between a first client and a match maker in accordance with the present invention

Fig 2 is a flow chart showing the interaction between a second client and a match maker in accordance with the present invention

Fig 3 is a flow chart showing the interaction between clients and the match maker of Figs 1 and 2 in accordance with the present invention.

Fig 4 is a flow chart showing measurement of communication attributes in accordance with the present invention.

Fig 5 is a flow chart showing the steps in matching in accordance with the present invention

Figs 6 and 7 are flow charts showing termination methods in accordance with the present invention

Fig. 8 is a flow chart showing the interaction of clients, servers and a match maker in accordance with the present invention

Figs 9- 10 are flow charts showing the use of communication attributes in accordance with the present invention

Fig 1 1 is a flow chart showing the matching operation of the match maker in Fig 8 DETAILED DESCRIPTION OF THE INVENTION

The present invention involves a network match making process running on a server system on a network that is used by clients to be matched into matched sets of clients for a multi-user application When the networked application operates in a networked system with multiple servers that may be used by the application, the network match maker also matches a server to the matched set of clients A key idea behind the present invention is that clients and the server are matched not only on the basis of user attributes, but also on

the basis of client, server and application attributes and on network performance characteristics including bandwidth, latency and packet loss

Attributes

The network match maker matches clients and a server into matched sets by comparing the attributes of the user, the client, the server and the properties of the network links between them to the requirements of the application

Client and user attributes

The user attributes include the obvious characteristics of the user that are relevant to the networked application Some examples include things such as skill level, age, people the user doesn't want to be matched with For the sake of a clearer discussion, the user and client attributes will be lumped into one group, and is referred to as "client attributes" Client attributes describe the capabilities of the client computer system The performance of the client computer, the type and performance of its network link and the types and versions of the networked applications that are installed on it are all reasonable examples of client attributes.

Application attributes

The application attributes are the requirements of the networked application Examples of these requirements include the type and performance of the client, the type and performance or any necessary server and the required properties of network links between the clients and between the clients and the server Application attributes come in two forms, class and instance The class attributes of an application apply to any instance of the application The networked match maker operates in an environment where there will be multiple instances of each application When an instance of an application is created, it inherits the class attributes while additional instance attributes may also be applied These instance attributes may simply override some of the class attributes inherited by the instance, while others may be specific only to application instances.

Server attributes

Example of static server attributes include the type and performance of the server system, types and versions of any networked application software that is installed on the server Dynamic attributes include the current load on the server Considering the current load on the server when assigning application instances to a server is a way of effect dynamic load balancing on he servers in a multiple server system

Communications attributes

Communications attributes are the properties of the network link between two computer systems These will include the links between clients and links between clients and a server The properties of network links will include the available bandwidth, the latency and the packet loss rate Many networked applications will have certain minimum requirements for bandwidth and maximum requirements for latency There are other metrics of communication performance that may be valuable measures of the properties of a communications link between two computer systems that also can be used Types of Matches

The network match maker forms matched sets of users by either automatically matching users into matched sets or allowing users to create match offers that other users may browse and then choose to join until full matched sets are completed. In both of these cases, the match maker will choose a server for the matched set if multiple servers are available and the networked application requires it. Automatic matching is a simple variant of user created match offers, so the user created match offer case is discussed first.

In both of these types of matches, there is the concept of a moderator. The moderator is the agent that chooses the instance attributes of a match offer. When the match offer is created, it inherits the class attributes of the application. The moderator may then modify the attributes to create the match offer instance attributes. When the application is launched for a match offer, it does so using the instance attributes of the match offer. In user created match offers, the most simple case is that the user that created the offer is the moderator. In automatic matches, the match maker itself is the moderator. Other possibilities exist. It is possible for some or all of the users in a match offer to share powers of the moderator. They may be able to override each others attribute choices so that the last setting of the attributes wins, or there may be a voting scheme between the users sharing moderator powers. It is also possible to imaging a mixture of match maker and user moderator powers. Some of the instance attributes might be set by the match maker and others by one or more users that join the match offer.

User Created Match Offers

Users may create their own specific offers to other users to match with These are called match offers. To create a match offer, the user will choose one application for which to create a match offer. The offer will inherit the class attributes of the application, but the user may add additional instance attributes for their specific match offer. The user that created the original match offer will be considered the moderator of that offer and will be the only one that is able to select the instance attributes of the match offer. Other users will browse these match offers, examine their attributes, select an offer that they find acceptable and attempt to join that offer. The match maker will compare the client attributes and the communications attributes of any relevant communication links to the required instance attributes If they do not match the required attributes of the match offer, the match maker will prevent the user from joining the match offer If they do match, the new client will join the offer and will be added to the matched set of clients associated with the offer As clients attempt to join the match offer, the match maker will also compare their attributes with those of the other clients to make sure that the user attributes are compatible before a client is allowed to join the match offer Once enough clients have joined the match offer, the moderator can select to launch the application How the network match maker determines how the properties of any relevant communications links affect which clients can join a match offer depends on the architecture of the networked application and is described in the following sections

Peer-to-peer When the client requests to join a match offer, the network match maker will ask the new client to measure the properties of the communications links between the new client and all of the existing clients that already are members of the match offer The properties of the communications links between the new client and the existing clients that are members of the match offer will be returned to the match maker in a vector of network properties These properties will be compared to the requirements of the instance attributes for the match offer The application will have its own class attributes for communications properties of the network links between the peers needed to run the application The creator of the match offer may override these attributes to create instance attributes for the properties of the communications links between the peers If the client attributes and the attributes of the communication links match the requirements of the application instance, the new client will be joined into the match offer Multiple clients to a single server

In this case, the server is assumed to have all of the necessary properties to host the necessary portions of the application. As with the peer-to-peer case when a client requests to join a match offer the network match maker will ask the new client to measure the properties of the communications links between the new client and all of the existing clients that already are members of the match offer. These properties will be returned to the match maker as a vector of communications properties which will be compared to the requirements of the application instance attributes for communications properties of client-to-client links. In this case the network match maker will also ask the new client to measure the properties of the communications link between the new client and the single server. The properties of this link are also matched to the instance attributes for communications properties of the client-to-server link. If all matches properly, the new client is allowed to join the match offer. In many multi-user networked applications that use a single server all client-to-client communications will be through the server, so there will be no direct client-to- client communications. In these cases, only the properties of the communications links from the clients to the server will be relevant. Multiple clients to multiple servers With multiple server systems, the situation becomes more complex. Not only must the system consider the properties of the communications links between the clients and the multiple servers, but additionally the attributes of the server systems. Not only must the network match maker match the clients into matched sets, it also must determine which of multiple server systems is to be associated with each matched set of clients. In the discussion here, it is assumed that the match maker will ultimately choose a single server to be matched with each matched set of clients associated with a match offer. The approach outlined here can be easily generalized to support applications that required multiple servers to be used when running a multi-user application. However, there are two server selection policies that the network match maker can use to select a specific server for a match offer called early server binding and late server binding.

When a client asks to join a match offer for a particular application, the network match maker asks the client to measure the properties of the communications links between itself, all of the other clients that are members of the matched set associated with the match offer and all of the server systems that are available for that application. The servers available for that application are a subset of all of the servers based on the attributes of the servers and the attributes for server requirements for the match offer instance. When a client creates a match offer they may specify instance attributes for the application that override or add to the application class attributes. This may further limit the subset of server systems that can support the application. When a new client requests to join the match offer, the network match maker will compare the client attributes to the required attributes of the match offer. If they match, the network match maker will then compare the properties of the relevant communications links to the requirements of the specific match offer.

With early server binding, the network match maker chooses the server from the qualified subset of servers using only the properties of the communications links between the creator of the match offer and the qualified servers. If multiple servers have communications links to the creator of the match offer that meet the requirements of the match offer, the network match maker will choose one based on some defined criteria. A reasonable criterion would be the best performance, but other criteria would be possible. As a new client attempts to join the match offer, the match maker compares the client attributes, the properties of the communications links between the new client and the existing members of the match offer and from the new client to the selected server. If all of these attributes and communications properties meet the requirements of the match offer, the client is allowed to join. While early server binding is the simplest server selection policy, it may not always result in the best server selection for all of the clients and it may prevent some clients from joining a match offer that they could have joined if a different server had been selected This is clearly the case if network latency is one of the important properties of a network link. With early binding, a qualified server with the lowest communications latency to the client creating the match offer will be chosen. This latency may be far lower than the latency required by the match offer The latency requirement of the match offer creates a virtual "sphere" around the chosen server. Clients that match the attributes of the match offer that are within the latency sphere centered around the chosen server will be able to join the match offer. Depending on the location in latency" space" of other qualified servers and other clients, another server may be a better choice that will not only allow the creator of the match offer, but more clients than the original server choice.

Server late binding eliminates this issue, but is more complex. With server late binding the network match maker maintains a pruned list of qualified servers for a match offer. The clients join the match offer in the usual way. The attributes of the new client are first compared to those of the match offer. If they match, the properties of the network links are compared. The match maker compares the properties of the network links between the new client and the member clients of the match offer to the instance attributes of the match offer. If they match, the properties of the network links between the client and the pruned list of servers is compared to the instance attributes of the match offer. If one or more of the communications links between the new client and the pruned list of servers meet the requirements of the match offer the client is allowed to join it. The network match maker then prunes the list of servers associated with the match offer to eliminate any for which the properties of the communications link from the new client to the server did not meet the instance attributes of the match offer. This will guarantee that the existing clients that are members of the match offer will continue to meet the requirements of the match offer. When the moderator finally chooses to launch the game, there may be more than one server in the pruned server list. The network match maker will select a final server using a selection criteria that it chooses Typically this selection criteria will choose the server with the best overall communications properties to all of the client that are members of the match offer In many network applications, there will be no direct communications between the clients There will only be communications between the clients and a server In this case there will be no need to measure properties of the communications links between the clients and so this will not be part of the match making process Automatic Matches

Automatic matches are very similar to user created match offers except that the users ask the match maker to create automatic match offers to match them with A user specifies an application to run and requests an automatic match The network match maker looks at the users requesting an automatic match of the same application and attempts to organize them into matched sets The match maker creates automatic match offers to which it matches the clients As part of creating an automatic match, the user may be given the ability to specify modifications to the attributes of the automatic match offer instance of an application As an example a user might ask for an automatic match for a game with only expert players

When a client requests an automatic match, match maker will compare the client attributes and communications properties of the requester as applicable to the attributes of the existing automatic match offers If the client attributes and applicable communications properties of the client match an automatic match offer, the client will be entered into the matched set of clients associated with the match offer If the attributes of a client and applicable communication properties do not match the instance attributes of the automatic match offer, the match maker will move on to the next automatic match offer This continues until the client has been matched to an automatic match offer, or there are no more automatic match offers If the new client has failed to match any of the automatic match offers, the network match maker creates a new automatic match offer and joins the new client with it When a particular automatic match offer contams enough clients as required by the attributes, the match maker causes an instance of the application to be launched The network match maker will also support a reasonable time-out period for the launching of automatic match offers The particular cases of peer-to-peer, multiple clients to single server and multiple clients to multiple servers are all handled in this frame work as they would with user created match offers A final detail of automatic match offers is that users that are manually browsing match offers will also see and be able to join the automatic match offers Examples of Communications Attributes

The most important communications attnbutes are bandwidth, latency and packet loss rate Other attributes of communications networks may be important in some applications, but these are the most broadly important attributes Below are examples of how these attributes would be used by the match maker for matching clients and servers to a match offer For the purposes of these examples, the discussion here relates only to how the communications attributes are used in the match making process The other client and server attπbutes will be ignored

Bandwidth is the data rate that can be supported by a particular network link Networked applications will have requirements for the data rates that they need to send between clients or between clients and a server Consider as an example an application that be operated with or without speech communications between the clients When used with digital speech, the speech data consumes a significant amount of data bandwidth Further consider that the application is a peer-to-peer application with no need for a server In this example a user creates a match offer for this application and sets an instance attribute for this match offer to enable speech communications When a new client requests to join the match offer, the match maker will ask the new client to measure the bandwidth between the new client and all of the clients that are already members of the match offer If the bandwidth between the new client and any one of the existing members of the match offer is too low to support the bandwidth requirements of the application when speech is enabled, the match maker will see that the client attributes for communications bandwidth to one of the existing clients does not match the instance attributes of the match offer for client-to-client communication bandwidth. The new client will therefore be prevented from joining the match offer. The same client may be allowed to join a match offer for the same application when the match offer instance specifies that client-to-client speech is not enabled. This will be true if the match offer instance attributes for client-to-client bandwidth are equal to or lower to the bandwidth from the new client to each of the existing client members of the match offer.

Latency is another important communications attribute. Latency is the time for a communications data to travel over a network link from one system to another. Many interactive applications will have strict requirements for communications latency that if not met will prevent the application from operating properly. Total latency on a communications link will be the sum of many factors including the propagation time of signals over long distances. The other factors can generally be minimized or reduced, but propagation delays are set by physical laws. Imagine a highly interactive game that is played between multiple clients through a server. Each client in a game instance sends and receives its communications data to the other clients through the server. In this example, also consider that the pool of potential clients to play the game are spread over a wide geographic area and that there are multiple servers also spread through the same area. The example game has strict latency requirements for the communications delay between the clients and a server used for a game instance. If the latency between a client and the server exceed this, the quality of the game play for the client or all of the clients in the game instance may be unacceptable. In this example, the match maker must not only match clients together into matched sets, but it also must match each matched set of clients to a specific server. As described earlier there are two methods of matching the server to a group of clients: early server binding and later server binding. With early server binding, the match maker will choose the server that has the lowest measured latency to the first client in the match offer. As each new client attempts to join the match offer, the match maker will ask the client to measure its latency to the server that has been selected for the match offer. If the measured latency meets the requirement of the match offer instance for latency, the new client will be allowed to join. The end result is that all of the clients that join the match offer will meet the requirements for latency of the match offer instance. With server late binding, when the match offer is initially created, the match maker will create a list of all of the servers that match all of the instance attributes of the match offer. As clients join the match offer, the match maker will ask the clients to measure their latency to each of the servers in the list. The new client will provide this vector of measured latencies to the match maker. Each latency in the vector will be compared to the latency attribute requirements of the match offer. If one or more the latency vector elements meet the latency requirements of the match offer, the new client will be allowed to join it. The match maker will then prune from the server list associated with the match offer any servers whose corresponding latency vector elements for the new client did not meet the requirements of the match offer. Once all of the desired clients have joined the match offer, there may be more than one server that are in the pruned list. The match maker will then use some criteria to select a single server. One criteria would be to choose the server that minimized the average latency between that server and all of the clients. Another criteria would be to rninimize the latency differences between each of the clients and the server. In a well managed network, most of the latency between two points in the network will come from the network propagation time. In both the early and late server binding cases, this will mean that the clients will tend to be matched to servers that are located near to them in the network. If the network tends to minimize the lengths of the network connections, this will result in clients being matched to servers in their geographical vicinity. Packet loss rate, is the rate at which data is lost during transmission in a network. Most networks transmit data in discrete units called packets or frames. Some networking protocols such as UDP do not provide guaranteed data delivery so it is up to the application to either be tolerant of transmission loss or provide a means to retransmit the data. Other networking protocols such as TCP/IP do provide guaranteed delivery. However, when a packet is lost this must be signaled to the sender and the transmission retried. Unfortunately, this takes time and introduces a large delay before the lost packet can be recovered. In some applications, this delay causes more problems than the loss of the data.

Therefore, many interactive applications will have requirements for maximum tolerated packet loss rates. This then becomes an important attribute of a network link that an application may want the match maker to consider as part of matching clients to a match offer and a server to matched set of clients. This attribute will be used in a similar fashion to the other network attributes.

Generalizations to the invention

The previous discussion of client- server applications only considers the cases where this is only a single server or the match maker chooses a single server from multiple servers to match to a match offer. It is also possible in the case where there are multiple servers that the application may require multiple servers. Consider an application that has two forms of data that it transmits through the network. As an example consider an interactive game that supports speech communications between players. It will transmit game information and user speech data that it separates into two separate data streams that flow between the clients and two different servers. One server will handle the game data while the other the speech data. This allows the server that handles the speech data to be equipped with special capabilities specific to processing the speech data prior to routing it to the clients that are to receive it.

With this arrangement, the application will require two servers, each with unique attributes. Since the game data and speech data will have different bandwidth, latency and packet loss requirements, the application will have separate requirements for each of the two data streams. This will mean that there will be two sets of application attributes for properties of the network links between the clients and the servers. During the match making process in this example, the match maker will ask a client requesting to join a match offer to measure the properties of the network links from the client to each of the two servers. For the client to be allowed to join the match offer, both sets of network properties must match the instance attributes of the match offer for the application requirements for each of the network links from a client to the two servers.

In the prior discussions it has been assumed that once a sufficient number of clients have joined a match offer for an application that the application is launched with all of the clients that have successfully joined the match offer. The launch may be triggered by a moderator in a user created match offer or may be triggered by the match maker when enough clients have been matched to an automatic match offer.

There is another important case of a persistent application. This is an application that allows clients to join and leave it during its operations. In this case, the game may be launched by a single client or automatically by the match maker. In this case, the running application also embodies a match offer. If the application requires a server or servers, they are chosen at the time that the application is launched. The server is chosen based on its attributes and the required attributes of the application. When a client requests to join the running application, the attributes of the client are compared to the required attributes of the application. The properties of the appropriate network links are measured and matched to the required network attributes of the application. If all matches, the new client is allowed to join the running application. At a later time the client may leave the application. This situation is the same as clients joining a match offer with early server binding. DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

Although the above description of the present invention is entirely enabling of the invention generally and of this embodiment in particular to a practitioner ordinarily skilled in the arts, as an aide to more quickly understanding the invention it is useful to consider in some detail an embodiment that contains only a relatively small subset of the invention and which is therefore relatively simple to describe and also is relatively quick and easy to understand.

The present embodiment relates to matchmaking for Peer to Peer games that is to say games that play without the use of any Servers even though the matchmaker is itself implemented as at least one Server. The network that this particular embodiment uses is the well known Internet which uses the also well known Internet Protocols (such as TCP/IP and UDP/TP). Moreover, for simplicity since the present embodiment is described only by way of illustration of the above described invention, only a relatively few of the possible alternatives are incorporated into this particular embodiment.

The term computer program is commonly abbreviated to program. A matchmaker server program is used, an executing instance of this program (abbreviated to MM) resides on a server computer. The concepts of server computers and executing instances of programs are well known in the computing arts. Each computer user (abbreviated to user in this embodiment) launches an instance of a client computer program on his computer which computer is then a client computer for the time being.

Referring to Fig. 1, in step 11, an instance of a client program (CL1) sends a request to the MM, the use of message exchanges by means of Internet communications to send requests is well known in the data communications and computing arts. The request asks the MM to create a game offer and the request includes attributes of the various game and match preferences chosen by the user together with intrinsic attributes of the requested type of game and attributes of the hardware and software installed on the user's computer. The intrinsic attributes of the game include limiting values for communications attributes of links between users' computers. In step 12, the MM receives this request. A well known intrinsic feature of the Internet Protocol (IP) used by CLl to send a request to the MM, is that all messages carry a return unique network address in the form of an Internet Protocol address (IPaddr.) exploiting which the MM can subsequently send a reply data message to the CLl , this eliminates any need for the CLl to embed an address within the request as might be needed on other types of network or link. In step 13 the MM creates a record to represent game offer (GORl) which contains the attributes from the request and the return unique network address of CLl . Records, sets of records and techniques for creating and maintaining them are well known in the computer programming art. In step 14 the MM sends a reply back to CLl notifying CLl that the match is not yet complete. In step 15 CLl waits for a request from MM. CLl thus becomes the first member of a game match yet to be completed. In step 16 the MM makes the contents of the game offer record available to other potential users. In step 17 MM waits for further requests from other clients.

Referring to Fig. 2, in step 21, another instance of a client program (CL2) which is executing on a different user's computer from CLl and also a different computer from MM, sends a request for a list of game offers to the

MM,. In step 22 the MM receives this request In step 23 the MM responds with information extracted from GORl that was created in step 13. In step 24 CLl receives the response from MM which contains the game offer information from GORl Referring to Fig. 3, in step 31, CL2 sends to MM a request to be matched into the offer represented by GORl . In step 32 the MM receives this request In step 33 the MM compares the attributes in the latest request sent by CL2 with those in GORl and if they do not match by whatever criteria the MM is programmed to use then CL2 is sent a message from MM that informs CL2 that it cannot join the offer represented by GORl, at least not at this time (step 34). The use of programmed criteria to match requirements and sets of requirements is well known in the computer programming art. Assuming the attributes match the in step 35 the MM sends to CL2 a request to measure the communications attributes between CLl and CL2.

Referring to Fig. 4, in step 41, CL2 receives the latest described request from MM. In step 42 a determination is made by MM as to whether the request is a request to measure comms. attribute or is a rejection. In step 43 CL2 measures the communications attributes of the data communications link between CL2 and CLl. Methods of measuring communications attributes are well known in the arts. Not all communications attributes are mutually orthogonal, though the especially important ones of latency, bandwidth and packet loss rate are indeed substantially orthogonal. For example, CL2 could measure a data throughput rate attribute directly or CL2 could measure latency, bandwidth and packet loss rate separately and then calculate data throughput rate to a reasonable degree of accuracy (limited inter-alia by mensuration precision) from those three attributes by methods well known in the data communications arts. Another communications attribute is best case round trip time for a kilobyte sized message, this attribute is a function of latency, bandwidth and as a second order effect computer speed but is entirely independent of packet loss rate. Round trip times and methods of measuring them are also well known in the arts. In step 44 CL2 reports the reports the results of measuring the attributes of the data communications link between CL2 and CLl back to MM. In step 45 MM receives the message reporting the results of the comms. attribute measurement.

Referring to Fig. 5, in step 51, the MM compares the communications attributes with the limiting values for communications attributes for the game recorded in GORl (or some predetermined default values for any limiting values for communications attributes absent from GORl) and if (step 52) the communications attributes exceed any limiting values for communications attributes specified in GORl (or, in their absence predetermined defaults) according to programmed criteria then in step 53 MM notifies CL2 that it is allowed to join the game offer and a further game offer record (GOR2) is created to record all the known attributes associated with CL2. Otherwise (step

54) CL2 is sent a message from MM that informs CL2 that it cannot join the offer represented by GORl (step 55).

Referring to Fig. 6, the MM must next determine whether or not the game match is complete. One vital criterion is whether sufficient players are joined into the game offer (step 61). This embodiment uses the automatic match approach, so if a sufficient number of instances of client programs are joined then a time-out timer is started (step 62) for a predetermined interval such as 30 seconds during which time further clients may join the game provided the maximum allowed number is players is not reached (step 63). Time-out timers are well known in the computer programming art. If a sufficient number of players is not yet joined then the time-out timer is not started yet and MM waits for more client (step 64)..

Until and unless the time-out timer expires further instances of client programs (CL3, CL4 etc) may join the game offer upon same basis of negotiation as CL2 used, with the exception that the third and later clients (CLn) will be requested and required by the MM to measure and report back the communications attributes between the candidate instance of client program and all of the clients already joined (CLl through CL(n-l)).

Referring to Fig. 7, in step 71, when and if the time-out timer expires MM deems the game matched and sends messages to each of the clients (CLl through CLn) to inform them of the successful completion of the game match. Otherwise MM takes no particular action in connection with the time-out timer (step 72), Upon receipt of the message informing them of the successful completion of the game match, each player's computer starts executing the game program instructions and each makes game data message exchanges between the each of users' computers upon a Peer to Peer basis. At this point communication between the clients and the MM (which is a server) is no longer essential and gameplay proceeds. Description of a Further Embodiment of the Invention

By way of further illustration the present embodiment is an example subset of the general description of the present invention, the subset being directed to matchmaking for a game that uses multiple clients to a single server with early server binding. The network that this particular embodiment uses is again the well known Internet. The above general description of the present invention is entirely enabling of the invention generally and of this embodiment in particular to a practitioner ordinarily skilled in the arts.

A matchmaker server program is used, an executing instance of this program (abbreviated to MM) resides on a server computer. Each computer user (abbreviated to user in this embodiment) launches an instance of a client computer program on his computer which computer is then a client computer. Referring to Fig. 8, in step 101, an instance of a client program (CLIO) sends a request to the MM. The request asks the MM to create a game offer and the request includes attributes of the various game and match preferences chosen by the user together with intrinsic attributes of the requested type of game and attributes of the hardware and software installed on the user's computer. The intrinsic attributes of the game include limiting values for communications attributes of links between clients and game servers (GSs). In step 102, the MM receives this request. In step 103 the MM creates a game offer record (GOR10) which contains the attributes from the request and the return unique network address of CLIO. In step 104 MM matches the attributes recorded in GOR10 with the attributes (if any) that game servers (GSs) have, at their own initiative, previously reported to MM and which MM retained in records created for this purpose. In the case that this matching of game server (GS) attributes to the attributes recorded in GORIO fails to identify a GS for which the attributes match GORIO adequately according to programmed criteria (step 105) then CLIO is sent a message from MM that informs CLIO that CLIO cannot join the offer represented by GORIO (step 106) Referring to Fig. 9, In step 111 the MM sends to CLIO a request to measure the communications attributes between CLIO and each of a shortlist of computers identified by the unique network addresses of all of the potentially compatible GSs identified by MM in step 104 above.

Referring to Fig. 10, in step 121, CLIO receives one of the latest described requests from MM. In step 123 CLIO measures the communications attributes of each of the data communications links between CLIO and the shortlisted GSs. In step 124 CLIO reports the results of measuring the various communications attributes back to MM. In step 125 the MM receives this report. Referring to Fig. 11, in step 131, the MM compares the communications attributes (for each path between CLIO and each of the GSs reported on) with the limiting values in GORIO (or some predetermined default values for communications attributes absent from GORIO) and if the communications attributes exceed the limiting values according to programmed criteria specified in GORIO or, in their absence predetermined defaults (step 132) then in step 133

CLIO is allowed to create a valid game offer by recording the unique network address of one of the qualifying servers in GORIO. This is termed early server binding. The server so selected (in step 133) is termed the early bound game server (EBGS). If no qualifying server is found then CLIO is sent a message from MM that informs CLIO that MM cannot create a game offer (step 135) and

GORIO is destroyed (step 136). Methods for destroying records are well known in the arts.

When further clients attempt to join the game offer represented by GORIO, they are requested by the MM to measure the communications attributes only between themselves and the EBGS. On reporting these communications attributes back to MM a determination is made as to whether those attributes exceed the limiting values according to programmed criteria established above so that the client may be allowed to join the game offer. This embodiment does not use the automatic match approach, so MM informs CLl 0 of the progress of the match as each client joins. When the user of CLIO is satisfied that a sufficient number of players have joined the match then the user of CLIO can stimulate CLIO to send a message commanding MM to treat the match as completed. User stimulation of programs through means such as (for example) keyboards or computer mice is well known in the computer prograrnrning arts. The MM then sends each client a message infoirning the client of the completion of the match.

Upon receipt of the message informing them of the successful completion of the game match, the each player's computer starts executing the game program instructions and makes game data message exchanges between the each user's computer and EBGS. At this point communication between the clients and the MM is no longer essential and gameplay proceeds.

Description of a Still Further Embodiment the Invention By way of further illustration the present embodiment is an example still further subset of the general description of the invention, this subset being directed to matchmaking for a game that uses multiple clients to multiple servers with late server binding. The network that this particular embodiment uses is again the well known Internet. The general description above is entirely enabling of the invention generally and of this embodiment in particular to a practitioner ordinarily skilled in the arts

A matchmaker server program is used, an executing instance of this program (MM) resides on a server computer. Each computer user (user) launches an instance of a client computer program on his computer which computer is then a client computer. An instance of a client program (CL20) sends a request to the MM. The request asks the MM to create a game offer and the request includes attributes of the various game and match preferences chosen by the user together with intrinsic attributes of the requested type of game and attributes of the hardware and software installed on the user's computer. The intrinsic attributes of the game include limiting values for communications attributes of links between clients and game servers (GSs). Next the MM receives this request. The MM creates a game offer record (GOR20) which contains the attributes from the request and the return unique network address of CL20. Then MM matches the attributes recorded in GOR20 with the attributes (if any) that game servers (GSs) have, at their own initiative, previously reported to MM and which

MM retained in records created for this purpose. In the case that this matching of game server (GS) attributes to the attributes recorded in GOR20 fails to identify a sufficient number of GSs (the number required is one of the attributes passed by CL20 to MM) for which the attributes match GOR20 adequately according to programmed criteria then CL20 is sent a message from MM that informs CL20 that it cannot join the offer represented by GOR20.

Next the MM sends to CL20 a request to measure the communications attributes between CL20 and each of a shortlist of computers identified by the unique network addresses of all of the potentially compatible GSs previously identified by MM.

Then CL20 receives the latest described request from MM. CL20 measures the communications attributes of each of the data communications links between CL20 and the shortlisted GSs. CL20 reports the results of measuring the various communications attributes back to MM. The MM compares the communications attributes (for each path between CL20 and each of the GSs reported on) with the limiting values in GOR20 (or some predetermined default values for communications attributes absent from GOR20) and if the communications attributes exceed the limiting values according to programmed criteria specified in GOR20 (or, in their absence predetermined defaults) then MM creates for CL20 a valid game offer by recording all the unique network addresses of all of the qualifying servers in GOR20

The network addresses in this list of unique network addresses is necessarily a subset of the shortlist referred to above The servers to be bound into the match are not yet selected because this embodiment uses late server binding

If an insufficient number of qualifying servers are found then CL20 is sent a message from MM that informs CL20 that MM cannot create a game offer and GOR20 is destroyed When further clients attempt to join the game offer represented by

GOR20, they are requested by the MM to measure the communications attributes between themselves and all of the servers listed in GOR20 as qualifying

On reporting these communications attributes back to MM a determination is made as to whether those attributes exceed the limiting values for a sufficient number of servers according to programmed criteria established above so that the client may be allowed to join the game offer If the client is allowed to join the game offer then any servers for which the communications attributes of the further client fail to meet criteria are removed from the list of qualifying servers in GOR20 Thus the list of qualifying servers may become smaller and smaller as more clients join the game offer

This embodiment does not use the automatic match approach, so MM informs CL20 of the progress of the match as each client joins When the user of CL20 is satisfied that a sufficient number of players have joined the match then the user of CL20 can stimulate CL20 to send a message commanding MM to treat the match as completed At this stage the MM selects the GSs to be bound into the match The servers most likely to result in good gameplay are chosen according to programmed criteria and other factors including all the reported communications attributes This is known as late server binding The MM sends to each server a notification that the match is complete together with a list of the addresses of the servers selected

Upon receipt of the message informing them of the successful completion of the game match, the each player's computer starts executing the game program instructions and makes game data message exchanges between the each user's computer and each bound server At this point communication between the clients and the MM is no longer essential and gameplay proceeds

It is to be understood that even though numerous embodiments and advantages of the present invention have been set forth in the foregoing description, the above disclosure is illustrative only, and changes may be made in detail yet remain within the broad principles of the invention. Therefore, the present invention is to be limited only by the appended claims

Claims

What is claimed is

1 A method for a match maker computer program to match an additional computer executing an instance of a client computer program with at least one of a plurality of existing computers executing instances of client computer programs, said instances executing on said existing computers having previously communicated to said match maker a desire to match with other instances of client computer programs, said additional and existing computers each being linked by a communication link, each of said instances executing on said additional and said existing computers having a set of attributes, said method comprising the steps of:

(a) receiving by said match maker computer program a request from said instance on said additional computer to match with one of said instances on said existing computer;

(b) sending an instruction to said instance on said additional computer in response to said request,

(c) measuring, by said instance on said additional computer in response to said instruction, a set of communication attributes between said instance on said additional computer and each of said instances on said existing computer, said measuring step including the step of sending a signal from said additional computer to said existing computers, said set of communication attributes relating to at least one parameter selected from a list consisting of latency, packet loss rate, and bandwidth; (d) selecting, if at least one member of said set of communication attributes exceeds a minimum performance requirement, at least one of said instances of said existing computers as a match to said instance on said additional computer based on said set of attributes and said set of communication attributes; and (e) waiting for a further request if no member of said set of communication attributes meets said minimum performance requirement

2 The method of claim 1 wherein said communication link comprises a network that uses Internet Protocols

3 The method of claim 2 wherein each of said instances on said existing computers contains a unique network address, said match maker creating a record containing said set of attributes and said unique network address for each instance on said existing computers

4 The method of claim 3 wherein said instance of additional computer contains a unique network address, and wherein said waiting step comprises the step of adding said set of attributes and said network address of said instance of additional computer to said record

5 The method of claim 1 wherein said minimum performance requirement is a predetermined default

6. A method for a match maker to match server computers and client computers, said match maker, said server computers and said client computers being connected to a data communication network, each of said server computers executing an instance of server program associated with a set of attributes and each of said client computers executing an instance of client program associated with a set of attributes, said method comprising the steps of: (a) receiving by said match maker a plurality of client requests from a plurality of instances of said client programs, each of said client requests containing said set of attributes associated with a corresponding instance of said client program,

(b) receiving by said match maker a plurality of server requests from a plurality of instances of said server programs each of said server requests containing said set of attributes associated with a corresponding instance of said server program,

(c) selecting at least two of said plurality of instances of said client programs and at least one of said plurality of instances of said server programs based of said sets of attributes contained in said client and said server requests, and

(d) connecting said client and said server computers executing said selected instances of said client and said server programs

7 A method for creating a first set of computer objects, said first set of computer objects comprising a plurality of instances of client computer programs together with at least a first instance of a server computer program selected from a first set of instances of server computer programs, each member of said first set of instances of server computer programs and each of said plurality of instances of client computer programs being associated with an unique network address, each member of said first set of instances of server computer programs and each of said plurality of instances of client computer programs being further associated with a set of attributes the method comprising the steps of

(a) constructing a first set of records, each record of said first set of records comprising a network address and a set of attributes associated with one member of said first set of instances of server computer programs,

(b) receiving from a first instance of a client computer program a first request to be enjoined into said first set of computer objects, said first request comprising an unique network address and a set of attributes, said unique network address of said first request being associated with said first instance of said client computer program, said set of attributes of said first request also being associated with said first instance of said client computer program,

(c) selecting a first subset of said first set of records in response to said first request by evaluating each member of said first set of records with reference to said set of attributes of said first request, (d) creating said first set of computer objects consisting of said first instance of said client computer program;

(e) augmenting said first set of computer objects with at least one further instance of said client computer program, comprising the steps of: (i) receiving from each of said at least one further instance of said client computer program a further request to be enjoined into said first set of computer objects, said further request comprising an unique network address and a set of, said unique network address of said further request being associated with said further instance of said client computer program, said set of attributes of said further request also being associated with said further instance of said client computer program;

(ii) removing from said first subset of said first set of records a further subset of said first set of records in response to said further request by evaluating each member of said first subset of said first set of records with reference to said set of attributes of said further request; and

(iii) adding to said first set of computer objects said further instance of said client computer program;

(f) constructing a second set of instances of server computer programs by selecting from members in said first set of instances of server computer programs having their network addresses appearing in said first subset of said first set of records; and

(g) adding to said first set of computer objects at least one member of said second set of instances of server computer programs by evaluating each member of said second set of instances of server computer programs with reference to said attributes of each member of said first set of computer objects .

8. The method of claim 1 wherein said set of attributes associated with one of said first and said further instances of said client computer programs includes attributes relating to capabilities of a computer system executing said one of said first and said further instance of said client computer programs.

9 The method of claim 1 wherein said set of attributes associated with one of said first and said further instances of said client computer programs includes attributes relating to characteristics of at least one user using said one of said first and said further instance of said client computer programs

10 The method of claim 1 wherein said set of attributes associated with one of said first and said further instances of said client computer programs includes communication attributes of network links associated with a computer system executing said one of said first and said further instance of said client computer programs.

1 1 The method of claim 4 wherein one of said communication attributes is bandwidth of said network link.

12 The method of claim 4 wherein one of said communication attributes is latency of said network link

13. The method of claim 4 wherein one of said communication attributes is packet loss rate of said network link

14 The method of claim 1 wherein said set of attributes associated with a member of said first set of instances of server computer programs includes attributes relating to capabilities of a computer system executing said member

15 The method of claim 1 wherein said set of attributes associated with a member of said first set of instances of server computer programs includes attributes relating to current load of a computer system executing said member

16 The method of claim 1 further comprising the step of finding an instance of server computer program from said first set of computer objects that 7/35258 PO7US97/04716

minimizes average latency between instances of server computer programs and instances of client computer programs belonging to said first set of computer objects.

17. The method of claim 1 wherein said augmenting step adds up to a predetermined number of instances of said client computer programs to said first set of computer objects.

18. The method of claim 1 wherein said augmenting step adds instances of said client computer programs to said first set of computer objects for up to a predetermined time interval.

19. The method of claim 1 wherein one of said sets of attributes associated with said first and said further instances of a client computer program is a set of multi-player game attributes.

20. The method of claim 13 further comprising a step of providing a moderator for constructing said set of game attributes.