Abstract:
A system and method for using a communication lease to open a communication channel is provided. An initiation terminal transmits a channel initiation request for access to a resource manager through a target terminal. Evaluation of a communication lease controlling access to the resource manager is awaited. Approval of the channel initiation request is received upon the successful evaluation of the communication lease. A communication channel is opened between the initiation terminal and the target terminal upon receipt of the approval.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is a continuation of U.S. Ser. No. 10/871,983 filed on Jun. 18, 2004 now U.S. Pat. No. 7,421,585, issued Sep. 2, 2008, the priority filing date of which is claimed, and the disclosure of which is incorporated by reference. 
    
    
     FIELD 
     This invention relates to the field of computer-mediated human communication systems, and, in particular to a system and method for using a communication lease to open a communication channel. 
     BACKGROUND 
     Existing access control mechanisms for human communication channels do not adequately reflect the dynamic nature of personal relationships, that is, (1) that people&#39;s management of their accessibility with respect to specific people evolves over time, (2) that people&#39;s management of their accessibility with respect to specific channels evolves over time, and (3) that accessibility is an asymmetric, interpersonal relationship that is socially negotiated on an ongoing basis. 
     Humans have a limited ability to process information through their senses. As a result, people typically limit the number of information channels that are simultaneously active around them. Human attention can be thought of as a limited resource that must be managed as more and more immediate inter-personal communication mechanisms arise. 
     In commonly-used communication systems, access control is “by obscurity”—once the address of a device (such as a phone number) is known, access is allowed for the indefinite future to all who know of, or who can be given, the address. From the perspective of the address&#39; owner, it would be desirable to be able to revoke access, but existing revocation methods have drawbacks: canceling an address puts administrative burdens on the address&#39; owner, and explicit revocation (as in password expiration) is heavyweight and often has negative social consequences. 
     Further, the desire for contact is often asymmetric and it can be socially awkward to refuse to provide contact information to another. For example, a person can be perceived as rude if they refuse to give someone their phone number. 
     Access control mechanisms in computer-mediated communication technologies do not adjust well to meet these challenges. More specifically, in many current technologies, access control mechanisms rely on access to a static piece of contact information, such as a phone number. Once someone has another person&#39;s phone number, email address, etc., they are able to contact that person until the phone number, email address, etc. is changed. Thus, this type of static access does not meet people&#39;s changing needs. 
     A few access control mechanisms exist that address a subset of these issues. For example, some existing mechanisms do provide support for timeouts. As a specific example, temporary phone numbers may be supplied as part of dating services. Such phone numbers are active for a specific duration of time; they cease to be active once that time period has passed and can not be renewed. 
     It would be advantageous to provide a mechanism for access control that enables negotiated evolution and revocation of a communication privilege in a socially-acceptable manner. 
     SUMMARY 
     An embodiment of the present invention provides a system and method for using a communication lease to open a communication channel. An initiation terminal transmits a channel initiation request for access to a resource manager through a target terminal. Evaluation of a communication lease controlling access to the resource manager is awaited. Approval of the channel initiation request is received upon the successful evaluation of the communication lease. A communication channel is opened between the initiation terminal and the target terminal upon receipt of the approval. 
     A further embodiment provides a system and method for controlling notification of availability of a resource manager. A request concerning availability of a resource manager is received from an initiation terminal. A communication lease including a lease identification and an access control between the initiation terminal and a target terminal is accessed. The access control is evaluated for satisfaction of at least one condition selected from the set including context-aware, renewable, exclusion, and proximity. The initiation terminal is notified of the availability of the target terminal upon satisfaction of the at least one condition. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments of the invention will be described in detail, with reference to the following figures wherein: 
         FIG. 1  illustrates a networked computer system in accordance with an embodiment; 
         FIG. 2  illustrates a computer-mediated communication system; 
         FIG. 3  illustrates one embodiment of a communication lease that can be used with one aspect of the invention; 
         FIG. 4  illustrates a lease-based human communication channel establishment process that can be used with one aspect of the invention; and 
         FIG. 5  illustrates a communication lease update process. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the invention provide a flexible mechanism to control access to communications between people and that provides social advantages over previous mechanisms. 
     One aspect of the invention is a communication system that uses communication leases for the purpose of access control for human communication channels. The communication system mediates access to a channel or content in a channel by computational means. By “human communication channel,” we mean a channel by which information is communicated to a person. One embodiment of the invention is a computer-mediated communication system. 
     Leases are the conceptual basis of a widely-applied model for resource management used in the design of distributed computing systems. Historically, a lease is defined to be “a contract by which one conveys real estate, equipment, or facilities for a specified term and for a specified rent; also: the act of such conveyance or the term for which it is made.” The lease model&#39;s derivation from the legal concept is largely by analogy—rents are usually abstract rather than monetary, the conveyance is of a virtual resource rather than real property, and the agents are usually system components rather than humans per se. 
     In the lease model, a resource manager leases access rights to a resource consumer for an explicitly negotiated duration. At the end of this duration, the resource manager manually or automatically revokes the resource consumer&#39;s rights (that is, the lease expires) unless the resource manager and resource consumer renegotiate and agree to renew the lease. In some embodiments the resource consumer can also voluntarily cancel a lease. 
     The key aspects of a leased resource, then, are: 
     
         
         
           
             Initial access is by negotiation between the resource manager and resource consumer. 
             In the absence of appropriate subsequent interaction, access to the resource expires without further action on the resource manager&#39;s part. 
             Renewal occurs only by negotiation, that is, if the resource manager and resource consumer both act and concur. 
           
         
       
    
     Because human attention is a limited resource that must be managed, communication leases can be used to control access to this resource. Communication leases share the aspects described above (negotiated initial access, automatic access expiration, negotiated access renewal). 
     Such an access control mechanism is often needed in modem telecommunications. For example, person A may want to limit person B&#39;s access to them to email contact, while they would like person C to be able to reach them via email or the phone. A person&#39;s interest in being contacted by another person therefore relates to both who can contact them and the human communication channel used by that person to do so. 
     What is required is a mechanism for access control that enables negotiated evolution and revocation in a socially-acceptable manner. One aspect of the invention is to provide leases of temporary duration that are renewable based on conditions. Leasing is a simple mechanism that specifies a set of key processes for local aspects of resource management (granting negotiations, implicit revocation, renewal negotiations). While the use of leases has been proposed for computer systems design, the application of leases in the domain of interpersonal computer-mediated communication has not. 
     One skilled in the art will understand that the network transmits information (such as data that can be operated on by a computer program as well as data that defines a computer program). This information can, but need not be, embodied within a carrier-wave. The term “carrier-wave” includes electromagnetic signals, visible or invisible light pulses, signals on a data bus, or signals transmitted over any wire, wireless, or optical fiber technology that allows information to be transmitted over a network. Programs and data are commonly read from both tangible physical media (such as a compact, floppy, or magnetic disk) and from a network. Thus, the network, like a tangible physical media, is a computer usable data carrier. 
     One skilled in the art will understand that a procedure is a self-consistent sequence of computerized steps that lead to a desired result. These steps can be defined by one or more computer instructions. These steps can be performed by a computer executing the instructions that define the steps. Thus, the term “procedure” can refer (for example, but without limitation) to a sequence of instructions, a sequence of instructions organized within a programmed-procedure or programmed-function, or a sequence of instructions organized within programmed-processes executing in one or more computers. Such a procedure can also be implemented directly in circuitry that performs the steps. The term logic includes circuitry that performs the procedure (both fixed circuitry) and programmed circuitry. 
       FIG. 1  illustrates a networked computer system  100  that can incorporate aspects of the invention. The networked computer system  100  includes a processor  101 , a memory  103 , a storage  105 , and an UO interface  107 . The l/O interface  107  provides the processor  101  with access to a network interface  109  (although in some embodiments the network interface  109  may be directly accessed) that enables the networked computer system  100  to communicate to a network (not shown). A program  111  can be loaded into the memory  103  so that the processor  101  can execute the instructions in the program  111 . The program  111  can be loaded into the memory  103  from the storage  105  (that can be a computer readable media such as a disk, read only memory, flash memory, or other data storage device that can be loaded into the networked computer system  100 ) or through the UO interface  107  or the network interface  109 . If the program  111  is downloaded through the network interface  109  it is generally transported by being embodied within an electromagnetic carrier wave or other wired or wireless data transfer technology. However, the program  111  could as well be received using any means of transferring data including audio wave modulation technology as well as any other data transfer means. The program  111  can be configured to cause the processor  101  to perform steps of at least one aspect of the invention. 
     The networked computer system  100  can be embodied as a personal computer, a telephone switch, a wired or wireless telephone, a network switch, and the like. The networked computer system  100  can also be embodied as custom circuitry that performs equivalent functions as that of a programmed computer system. 
       FIG. 2  illustrates a computer-mediated communication system  200  that includes a network  201  that includes a communication switch  203  (such as an analog or digital telephone switch; or a networking switch using, for example, ATM or TCP/IP protocols). The network  201  can be used to create a human communication channel  205  between an initiator communication means such as an initiating terminal  207  and a target communication means such as a target terminal  209 . A communication lease  211  or a communication lease identification  212  can reside at the initiating terminal  207 , within the communication switch  203 , or within the target terminal  209 . Information related to the communication lease  211  can be exchanged, if needed, between the initiating terminal  207 , the target terminal  209 , and the communication switch  203  using the network  201  or an out-of-band communication channel  213 . Further, in some embodiments separate portions of the communication lease  211  can be distributed throughout the components in the computer-mediated communication system  200 . 
     The initiating terminal  207  is operated by a resource consumer  217  who desires to access the resource controlled by a resource manager  219  through the use of the communication lease  211 . 
     According to one embodiment, the resource is that of access to the resource manager  219 ; the human communication channel  205  can provide either direct access or indirect access to the resource manager  219  through the target communication means. An example of a direct access is a telephone communication with the resource manager  219  or an e-mail that is not directed into a secondary folder (such as by a filter). An example of an indirect access through the target communication means is a voice message left for the resource manager  219  or directed into a secondary folder. The human communication channel  205  as used in this patent is not limited to the creation of a communication mechanism that requires each end of the channel be simultaneously open. Thus, the concept of the human communication channel  205  includes both synchronous (such as with a telephone system) and asynchronous communications (such as an e-mail system). In addition, the initiator communication means and the target communication means can have all the described functionality within a single device or can have the functionality distributed between multiple devices. 
     Thus, the initiator communication means and the target communication means are contemplated to be terminals for communication channels that include half- or full-duplex transmission, synchronous or asynchronous media, and audio, video, or textual content (for example, a computer terminal; a paging system, a wired, wireless, or cellular telephone device using push-to-talk technology (both immediate and store-and-forward) or standard POTS or cellular telephone technology; a two-way video conference device and the like). In addition, the target communication means (such as the target terminal  209 ) can include separate or combined capabilities such as separate or combined caller-id capability, communication lease authentication capability, voice-mail capability, and other optional capabilities. The initiator communication means (such as the initiating terminal  207 ) can also have a biometric identification reader, a short-range or contact-based data transfer reader (such as an RFID reader), a data storage access device, a data storage device, as well as other optional capabilities. 
     The inventors contemplate that the computer-mediated communication system  200  encompasses communication systems such as modem telephone systems, cellular telephone systems, push-to-talk communication systems, Voice over Internet Protocol systems, e-mail systems, instant messaging systems, and other electronic communication systems used by humans that have the ability to compute whether a human communication channel is to be established (or can be augmented with such an ability by applying the techniques disclosed herein). 
     A computer or other data processing capable device can be used to reference (access) the communication lease and to evaluate the lease&#39;s access control as it is applied to the resource manager  219  and the resource consumer  217  during an attempt to establish the human communication channel  205  between the resource consumer and the resource manager. This device can be located, for example, at the communication switch  203 , at the target terminal  209  (either directly within the terminal or attached to the terminal) or can be a computer program executing on a personal computer to evaluate the lease and control access. In addition, the communication lease  211  can be stored on a completely independent location on the network and need not reside within the communication switch  203  or the target terminal  209  so long as these devices can access the communication lease  211  when needed. 
     One skilled in the art will notice that while the lease can be tied to a particular address for the resource consumer  217  (for example, a telephone number, e-mail address etc.), it need not be. Other validation mechanisms can be used to identify and authorize access to the lease. These include password and other authentication techniques known in the art. 
       FIG. 3  illustrates one embodiment of a communication lease  300 . One skilled in the art will understand that there are many possible ways to organize the lease data (including tables, as hierarchal structures of various kinds, databases and the like). The communication lease  300  generally includes a ‘resource consumer identification’ field  301  that identifies or provides a way to identify the resource consumer, a ‘contact information’ field  303  that provides information about the initiating terminal  207  used to make a contact (for example, an internet address, a telephone number, password, lease identification or other similar information depending on the type of contact), a ‘contact classification’ field  305  that identifies the type of the information in the ‘contact information’ field  303 , a ‘duration’ field  307  that specifies the effective timeframe of the communication lease  300  (for example, this field can contain a ‘default expiration date’ for the communication lease, as well as a ‘leasedisabled delay’ for an exclusion lease), a ‘condition’ field  309  that maintains the lease conditions (status, rules or programs) used to define an access control between the resource consumer  217  and the resource manager  219 , and an ‘other’ field  311  for other lease information. 
     Furthermore, the communication lease  300  includes a ‘resource manager identification’ field  313  that identifies or provides a way to identify the resource manager who controls the lease, a ‘contact information’ field  315  for the resource manager (in this embodiment, the communication lease  300  assumes that the ‘contact classification’ field  305  applies to both the ‘contact information’ field  303  and the ‘contact information’ field  315 ; however, other embodiments need not require that the resource consumer  217  and the resource manager  219  communicate using devices that have the same contact classification), a ‘security information’ field  317  that maintains any required security information (such as a public key portion of a public-private key pair), and a ‘history information’ field  319  that maintains history information such as a log of the communications between the resource manager  219  and the resource consumer  217  that use the communication lease  300 . 
     One skilled in the art will understand that the communication lease can have many different formats. Such formats can include splitting the communication lease between the resource consumer  217  and the resource manager  219  such that each party can monitor contact and communication history between the parties (further, portions of the communication lease can be distributed to other portions of the communication system). 
     In one embodiment, the resource manager  219  only has a restricted number of communication leases so that the resource manager  219  can plausibly justify cancellation of the communication lease due to the scarcity of communication leases available to the resource manager  219 . This restriction can be a result of the expense of the lease, or a limit to the number of available leases. In addition, the communication lease can be a context-aware lease, a renewable lease, an exclusion lease or other type of lease. 
     A context-aware lease is one that maintains history information in the ‘history information’ field  319  such that the access control of the communication lease  300  will cause the lease to expire on satisfaction of a lease condition (for example, after some set of conditions are met). For example, one lease condition could be satisfied when there is a limited amount of communication or contact between the resource consumer  217  and the resource manager  219  over some time period, when the resource manager  219  has not returned communication attempts by the resource consumer  217 , or the parties have not had personal contact or other communications over some time period. The context-aware lease provides an automatic expiration of the communication lease and adds the social ambiguity that the expiration of the lease is automatic. 
     A renewable lease is one that allows the resource manager  219  to explicitly renew the communication lease as it nears the end of its duration. In addition, the communication lease can be implicitly renewed by the access control of the lease on behalf of the resource manager  219  if conditions (captured in the ‘history information’ field  319 ) specified by the resource manager  219  are satisfied. In one embodiment the resource consumer  217  is not notified of the expiration or renewal of the communication lease (thus adding to the social ambiguity). 
     As will be described below, some embodiments of the renewable lease provide various types of ambiguity which make revocation of access more socially acceptable. By allowing automatic expiration (implicit revocation), the renewable lease generally leaves the resource consumer  217  with several alternative explanations for how the loss of access to the resource manager  219  actually occurred. Additionally, in some embodiments, the resource consumer  217  may receive little detailed information about what is going on, making it difficult to tell whether access was lost because of an explicit action (lease revocation) by the resource manager  219 , an implicit action (lease expiration by the access control), a system failure, and the like. 
     Motivation for action. By imposing a user-visible notion of resource scarcity, an embodiment of the renewable lease that restricts the number of communication leases offers a largely depersonalized and plausible motivation for an actual evocation or a failure to renew by the resource manager  219 . For example, if pressed, the resource manager  219  can argue that he/she needed to allocate the communication lease to someone else due to some kind of contingency. (Personal motivations are generally more offensive). 
     Identity of actor. In an embodiment of the renewable lease that exposes the role of the system in expiring the lease, the system is a “third actor” (along with the resource manager  219  and the resource consumer  217 ), so there is ambiguity about which party acted to cause the change. (An action by the resource manager  219  is generally more offensive than action that can be attributed to the system). 
     Nature of action taken. In an embodiment of the renewable lease such that the resource consumer  217  is not notified as to what specific actions, if any, have been taken by the resource manager  219  (although these actions can be somewhat inferred), it is ambiguous whether implicit or explicit action occurred. (Explicit action by the resource manager  219  is generally more offensive than implicit action, which can be attributed to carelessness). 
     Time/context of action. In an embodiment of the renewable lease such that the resource consumer  217  is not notified when the communication lease expires, there is ambiguity as to when the change occurred; this is similar to the resource manager  219  changing his/her phone number and not contacting the resource consumer  217  to provide the new phone number. The resource consumer  217  may not even detect that the communication lease has not been renewed, or they may discover this so long after the fact that it is less offensive. 
     While this may intuitively feel manipulative and undesirable, in fact, the smooth progress (avoidance of confrontation) in daily situations of this kind relies heavily on such ambiguity as well as the willingness of all parties to let ambiguous accounts stand in order to preserve face. 
     Another communication lease is the exclusion lease. This communication lease is a variant of other communication leases that includes an additional condition that excludes communication initiated by the resource consumer  217  for some period of time. It explicitly states that communication initiated by the resource consumer  217  will not be accepted for some period of time, but after that period, communication can again be initiated by the resource consumer  217 . In general, the exclusion lease will automatically convert into another form of communication lease (such as a context-aware lease or a renewable lease) at the end of its exclusion duration. 
     In some embodiments, the communication lease  300  can be structured so that the lease can be associated with a physical embodiment such that the resource manager  219  can physically provide the resource consumer  217  with a tangible representation of the communication lease. This could be accomplished, for example, by providing the resource consumer  217  with an encrypted data file on a flash memory, by providing a small RFID device that contains an identifier for the communication lease (in one embodiment, the inventers contemplate providing a RFID bead that could be attached to a charm bracelet), or other data transfer techniques known in the art (for example, using a storage device such as an RFID tag, a computer readable storage media, a memory device, a data file, a barcode printed on media, a pattern printed on media, and text printed on media). In addition some embodiments require that the resource consumer  217  provide some other information (such as biometric information, a password, a public key, etc.) along with the communication lease or communication lease identifier (for example, a URL, or other network identifier). 
     There are many ways to structure access to the communication lease. For example, the communication lease can be stored within the network  201 , the communication switch  203 , or with the target communication means. In addition, an identifier of the communication lease can be stored or made accessible to the initiator communication means. In some embodiments, the communication lease (or a copy thereof) can be stored at the initiator communication means. 
       FIG. 4  illustrates a lease-based human communication channel establishment process  400  that initiates at a ‘receive channel initiation request’ procedure  401 . This process can be performed by a communication system, a communication switch and by the target communication means. The channel initiation request results from the resource consumer using the initiator communication means (such as the initiating terminal  207 ) to attempt to open a human communication channel to the resource manager at the target communication means (such as the target terminal  209 ). The channel initiation request is received by receiver logic (or detection logic) and generally includes information about the initiator communication means and the target communication means (such as an identification of the initiating terminal  207  and the target terminal  209 ). The initiating request, for example, can include the communication lease identifier, a biometric reading of the resource consumer  217 , a password known by the resource consumer  217 , a public-key of the resource consumer  217 , etc. The initiating request can consist of multiple protocol steps (in a telephone system for example, sending a caller ID to the target terminal  209 , detecting a connection, sending a communication lease identification, receiving approval for the human communication channel and then opening the human communication channel). The actual protocol steps depend on the configuration of the computer-mediated communication system  200  and the details as to where and how the communication lease is stored and accessed. One skilled in the art would be able to implement such a protocol without undue experimentation. 
     The ‘receive channel initiation request’ procedure  401  can be accomplished at the target terminal  209  or the communication switch  203  depending on the embodiment. 
     Once the channel initiation request is received, the lease-based human communication channel establishment process  400  continues to an ‘access communication lease’ procedure  403  that references or locates and references the communication lease  211  using lease look-up logic. The reference to the communication lease  211  is generally by accessing the lease (opening the lease, reading the lease etc.). In embodiments where the communication lease is accessible by the communication switch  203 , the switch can locate the communication lease using information in the ‘contact information’ field  303  and in the ‘contact information’ field  315 , as well as information provided by the resource consumer  217  (such as a password, lease identification, biometric data, etc). 
     In embodiments where the communication lease is accessible (referenced) by the target terminal  209 , the terminal can locate the communication lease using information in the ‘contact information’ field  303 , as well as information provided by the resource consumer  217  (such as a password, lease identification, biometric data, etc.). 
     In embodiments where the communication lease identification  212  is accessible by the initiating terminal  207 , the initiator communication means can send the communication lease identification  212  directly to the target communication means along with information provided by the resource consumer  217  (such as a password, lease identification, biometric data, etc.). The communication lease identification  212  can be provided to the resource consumer  217  in the form of an RFID bead, a data file transmitted over a network, a data file provided on a computer readable media, etc. The target communication means can then reference (access) the communication lease  211  identified by the communication lease identification  212 . 
     Once the communication lease  211  is referenced, an ‘evaluate access control’ procedure  405  can use decision logic that evaluates the state of the communication lease  211  by, for example, processing rules that can be stored in the ‘condition’ field  309  that access lease fields such as the ‘duration’ field  307 , other portions of the ‘condition’ field  309 , the ‘history information’ field  319 , etc. An ‘allow communication’ decision procedure  407  uses the results of the ‘evaluate access control’ procedure  405  to determine whether the conditions in the communication lease  211  allow creation of the human communication channel  205 . If the communication lease  211  has expired, or if other conditions related to the communication lease  211  are not met, the lease-based human communication channel establishment process  400  continues to a ‘disallow communication’ procedure  409  and no direct or indirect human communication channel will be created between the resource consumer  217  and the resource manager  219 . 
     Some embodiments may allow indirect communication. For example, a telephone answering machine that includes an embodiment of the invention can be configured to only accept telephone calls (and generate a ring) from resource consumers who have valid leases. Thus, the phone of the resource manager  219  would only ring for call attempts from resource consumers who have a valid communication lease. The telephone answering machine could also be configured such that call attempts that invoke an invalid lease would not cause a ring but could allow voice messages from the associated resource consumer  217  to be captured. Some leases can be configured so that they provide access only through voice messaging such that there would never be a direct communication between the resource consumer  217  and the resource manager  219 . 
     After the ‘disallow communication’ procedure  409 , the lease-based human communication channel establishment process  400  continues to an ‘end’ terminal  411 . 
     If at the ‘allow communication’ decision procedure  407 , the communication lease conditions are satisfied, the lease-based human communication channel establishment process  400  continues to an ‘update lease information’ procedure  413  that accesses the communication lease  300  to update the ‘history information’ field  319  to show that the resource consumer  217  attempted to contact the resource manager  219  and that the lease allowed the direct or indirect connection. An ‘establish communication’ procedure  415  then completes the human communication channel  205  and the lease-based human communication channel establishment process  400  completes through the ‘end’ terminal  411 . 
     One skilled in the art will understand that some embodiments can additionally track rejected attempts to establish the human communication channel  205 , can track information about the duration of communication, and in some embodiments may provide the ability to record all or portions of the communications. In addition, embodiments that provide the ability to record all or portions of the communications may process the communication content using known techniques for assessing contextual states of the communicating parties. One use of these contextual state assessments is as an input to processing rules that can be stored in the ‘condition’ field  309 . For example, known techniques for probabilistic estimation of human emotional state from acoustic features of human speech can be applied to recorded communications. These probabilistic estimates can be used in various kinds of processing rules, such as processing rules that disallow communication at the current time or reduce the communication lease duration to hasten its expiration. A history of contextual state assessments can additionally be stored in the ‘history information’ field  319 . 
     The out-of-band communication channel  213  is any communication related to the lease that is performed outside of the human communication channel  205 . This includes communications between ubiquitous computing devices as well as communications that result from the passing of data between the parties, or changes made to the lease directly by the resource manager  219 . While information regarding activity over the human communication channel  205  can be saved in the lease responsive to communication attempts, information gathered from the out-of-band communication channel  213  can also be saved in the lease for later use. 
     The type and conditions of the communication lease  211  can be negotiated between the resource consumer  217  and the resource manager  219 . In addition, the resource manager  219  can initially provide the lease on an as-is basis. Access to the lease can be provided to the resource consumer  217  through sharing of a file (such as by sharing information between PDA&#39;s, cellular phones, or other ubiquitous computing device), memory stick, flash memory, RFID device, etc. that contains either a portion of the lease or an identification of the lease. 
     The information in the ‘history information’ field  319  can be updated by attempted, successful direct and indirect contacts, and unsuccessful contacts between the resource consumer  217  and the resource manager  219  including contacts initiated by the resource manager  219 . In addition, with discovery protocols in Bluetooth enabled devices, Wi-Fi enabled devices and other ubiquitous computing devices, the communication lease can collect information regarding occasions when the resource consumer  217  and the resource manager  219  were in physical proximity (for example, within the discovery range of the devices, or by exchanging Global Positioning System information). This implicit contact information can also be incorporated in the access control decision process. 
       FIG. 5  illustrates a communication lease update process  500  that can be used to detect conditions that modify the communication lease  300 . The communication lease update process  500  initiates at a start terminal  501  responsive to the resource manager  219  explicitly initiating a modification to the lease. The communication lease update process  500  can also be initiated by the ‘update lease information’ procedure  413  of  FIG. 4 . Once initiated, the communication lease update process  500  continues to a ‘monitor interactions’ procedure  503  that monitors the commands specified by the resource manager  219 , as well as operations that could cause changes in the ‘history information’ field  319  (such as successful direct or indirect contacts, and when the parties are within local proximity of each other, as well as expiration of duration etc.). A ‘detect lease modification condition’ procedure  505  detects when the communication lease  300  needs to be modified. When that condition is met, the communication lease update process  500  continues to an ‘update lease’ procedure  507  that updates the portions of the lease affected by the condition. This update can disable or enable the lease, can update the ‘history information’ field  319 , or update or change any other field in the lease. Once the lease is updated, the communication lease update process  500  continues back to the ‘monitor interactions’ procedure  503 . 
     Yet another aspect of the invention is that of controlling notification of the resource consumer of the presence (or availability) of the resource manager. One example where a communication lease could be used with this aspect of the invention is that of an instant messaging system. These systems allow one person to generally know when another person is accessible by presenting presence information. In computer-mediated communication systems that present presence information, it would be desirable to control on an individual basis who can receive presence information. Controlling access to presence information poses many of the same social difficulties as controlling access to other human communication resources (such as direct or indirect access to a resource manager). For example, explicitly revoking access to presence information may be considered rude, just as explicitly blocking other forms of communication may be considered rude. Communication leases can be applied to the problem of access control to presence information. In this case, the resource being managed is access to a particular resource manager&#39;s presence information, and the human communication channel is the channel passing presence information between the resource manager and the resource consumer. This aspect of the invention would be very relevant to instant messaging systems, push-to-talk communication systems, as well as generally useful in other human communication technologies that utilize presence information. 
     One skilled in the art will understand that aspects of the invention provide a person with increased control over electronic or computer-mediated communications with others. The need for this increased control results from the realization that: (1) people&#39;s management of their accessibility with respect to specific people evolves over time, (2) people&#39;s management of their accessibility with respect to specific channels evolves over time, and (3) accessibility is an asymmetric, interpersonal relationship that is socially negotiated on an ongoing basis. Aspects of the invention provide a more flexible mechanism for access control that provides social advantages over previous mechanisms. 
     Although aspects of the present invention have been discussed in terms of the embodiments described herein, one skilled in the art will understand that various modifications and alterations may be made without departing from the scope of the invention. Accordingly, the scope of the invention is not to be limited to the particular invention embodiments discussed herein.