Abstract:
An application program interface (API) for sending and receiving endpoint registration data and peer-to-peer network cloud data has a registration call for adding endpoint data to a peer-to-peer network. The API may receive explicit data regarding address information or may be instructed to select and maintain suitable address information as the topology of the peer-to-peer network changes. Blocking and non-blocking calls are exposed for retrieving information peer-to-peer network endpoint data.

Description:
BACKGROUND 
     Peer-to-peer networking offers users many opportunities for collaboration and sharing by connecting computers associated by geography or network characteristics. The chance to offer and discover services, files, data, and programmatic offerings increases flexibility and utilization of computing resources. 
     A peer-to-peer network may include similar groupings of computers in clusters known as clouds. Clouds may be identified by their scope or by other attributes such as a department it is associated with. Multiple clouds may exist within a given company or organizational entity. Offerings available on the peer-to-peer network are known as endpoints. Endpoints may be computers, files, or programs. However, endpoints may also include services that are available at more than one physical location on the peer-to-peer network, that is, a service may have multiple Internet Protocol addresses and/or IP ports. 
     Endpoints that wish to join or maintain contact with a peer-to-peer network may use a service called the “Peer Name Resolution Protocol” (PNRP). PNRP is currently accessible via two mechanisms, a GetAddrInfo application program interface (API) or a Winsock Namespace Provider API. The GetAddrInfo API is relatively simple but does not make available all the functionality of PNRP. The NamespaceProvider API supports all the features of PNRP but has been found cumbersome and difficult to use by some developers. Beyond the coding challenges, the prior art APIs increased the difficulty of debugging systems incorporating PNRP. The adoption of PNRP and subsequently, the robust features available through PNRP for peer-to-peer networking, has been hampered by the difficulty of using the APIs currently available. 
     SUMMARY 
     The Simple PNRP API exposes all the functions available in PNRP while simplifying the programming and management overhead associated with building and maintaining peer-to-peer networks. Broadly, there are a class of calls for registering and updating endpoint information in a peer-to-peer network and another class of calls for discovering endpoints in the peer-to-peer network. The discovery calls may be blocking or non-blocking. The use of these simplified calls is expected to increase the utilization of PNRP by streamlining both the development and use of PNRP for peer-to-peer networks. 
     The Simple PNRP APIs greatly eases the developer&#39;s burden for coding PNRP interfaces and simplifies the debugging process during development and testing. The Simple PNRP APIs are expected to significantly advance the adoption of PNRP and, through that, the adoption of peer-to-peer networking in an increasing number of consumer, commercial, and business applications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simplified and representative block diagram of a computer network; 
         FIG. 2  is a block diagram of a computer that may be connected to the network of  FIG. 1 ; 
         FIG. 3  is a simplified and representative block diagram of a peer-to-peer network; and 
         FIG. 4  is a simplified and representative block diagram of a peer-to-peer network. 
     
    
    
     DETAILED DESCRIPTION 
     Although the following text sets forth a detailed description of numerous different embodiments, it should be understood that the legal scope of the description is defined by the words of the claims set forth at the end of this disclosure. The detailed description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims. 
     It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘______’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term by limited, by implication or otherwise, to that single meaning. Finally, unless a claim element is defined by reciting the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. §112, sixth paragraph. 
     Much of the inventive functionality and many of the inventive principles are best implemented with or in software programs or instructions and integrated circuits (ICs) such as application specific ICs. It is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation. Therefore, in the interest of brevity and minimization of any risk of obscuring the principles and concepts in accordance to the present invention, further discussion of such software and ICs, if any, will be limited to the essentials with respect to the principles and concepts of the preferred embodiments. 
       FIGS. 1 and 2  provide a structural basis for the network and computational platforms related to the instant disclosure. 
       FIG. 1  illustrates a network  10 . The network  10  may be the Internet, a virtual private network (VPN), or any other network that allows one or more computers, communication devices, databases, etc., to be communicatively connected to each other. The network  10  may be connected to a personal computer  12 , and a computer terminal  14  via an Ethernet  16  and a router  18 , and a landline  20 . The Ethernet  16  may be a subnet of a larger Internet Protocol network. Other networked resources, such as projectors or printers (not depicted), may also be supported via the Ethernet  16  or another data network. On the other hand, the network  10  may be wirelessly connected to a laptop computer  22  and a personal data assistant  24  via a wireless communication station  26  and a wireless link  28 . Similarly, a server  30  may be connected to the network  10  using a communication link  32  and a mainframe  34  may be connected to the network  10  using another communication link  36 . The network  10  may be useful for supporting peer-to-peer network traffic. 
       FIG. 2  illustrates a computing device in the form of a computer  110 . Components of the computer  110  may include, but are not limited to a processing unit  120 , a system memory  130 , and a system bus  121  that couples various system components including the system memory to the processing unit  120 . The system bus  121  may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnect (PCI) bus also known as Mezzanine bus. 
     Computer  110  typically includes a variety of computer readable media. Computer readable media can be any available media that can be accessed by computer  110  and includes both volatile and nonvolatile media, removable and non-removable media. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, FLASH memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by computer  110 . Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, radio frequency, infrared and other wireless media. Combinations of any of the above should also be included within the scope of computer readable media. 
     The system memory  130  includes computer storage media in the form of volatile and/or nonvolatile memory such as read only memory (ROM)  131  and random access memory (RAM)  132 . A basic input/output system  133  (BIOS), containing the basic routines that help to transfer information between elements within computer  110 , such as during start-up, is typically stored in ROM  131 . RAM  132  typically contains data and/or program modules that are immediately accessible to and/or presently being operated on by processing unit  120 . By way of example, and not limitation,  FIG. 2  illustrates operating system  134 , application programs  135 , other program modules  136 , and program data  137 . 
     The computer  110  may also include other removable/non-removable, volatile/nonvolatile computer storage media. By way of example only,  FIG. 2  illustrates a hard disk drive  141  that reads from or writes to non-removable, nonvolatile magnetic media, a magnetic disk drive  151  that reads from or writes to a removable, nonvolatile magnetic disk  152 , and an optical disk drive  155  that reads from or writes to a removable, nonvolatile optical disk  156  such as a CD ROM or other optical media. Other removable/non-removable, volatile/nonvolatile computer storage media that can be used in the exemplary operating environment include, but are not limited to, magnetic tape cassettes, flash memory cards, digital versatile disks, digital video tape, solid state RAM, solid state ROM, and the like. The hard disk drive  141  is typically connected to the system bus  121  through a non-removable memory interface such as interface  140 , and magnetic disk drive  151  and optical disk drive  155  are typically connected to the system bus  121  by a removable memory interface, such as interface  150 . 
     The drives and their associated computer storage media discussed above and illustrated in  FIG. 2 , provide storage of computer readable instructions, data structures, program modules and other data for the computer  110 . In  FIG. 2 , for example, hard disk drive  141  is illustrated as storing operating system  144 , application programs  145 , other program modules  146 , and program data  147 . Note that these components can either be the same as or different from operating system  134 , application programs  135 , other program modules  136 , and program data  137 . Operating system  144 , application programs  145 , other program modules  146 , and program data  147  are given different numbers here to illustrate that, at a minimum, they are different copies. A user may enter commands and information into the computer  20  through input devices such as a keyboard  162  and cursor control device  161 , commonly referred to as a mouse, trackball, or touch pad. A camera  163 , such as web camera (webcam), may capture and input pictures of an environment associated with the computer  110 , such as providing pictures of users. The webcam  163  may capture pictures on demand, for example, when instructed by a user, or may take pictures periodically under the control of the computer  110 . Other input devices (not shown) may include a microphone, joystick, game pad, satellite dish, scanner, or the like. These and other input devices are often connected to the processing unit  120  through an input interface  160  that is coupled to the system bus, but may be connected by other interface and bus structures, such as a parallel port, game port or a universal serial bus (USB). A monitor  191  or other type of display device is also connected to the system bus  121  via an interface, such as a graphics controller  190 . In addition to the monitor, computers may also include other peripheral output devices such as speakers  197  and printer  196 , which may be connected through an output peripheral interface  195 . 
     The computer  110  may operate in a networked environment using logical connections to one or more remote computers, such as a remote computer  180 . The remote computer  180  may be a personal computer, a server, a router, a network PC, a peer device or other common network node, and typically includes many or all of the elements described above relative to the computer  110 , although only a memory storage device  181  has been illustrated in  FIG. 2 . The logical connections depicted in  FIG. 2  include a local area network (LAN)  171  and a wide area network (WAN)  173 , but may also include other networks. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets and the Internet. 
     When used in a LAN networking environment, the computer  110  is connected to the LAN  171  through a network interface or adapter  170 . When used in a WAN networking environment, the computer  110  typically includes a modem  172  or other means for establishing communications over the WAN  173 , such as the Internet. The modem  172 , which may be internal or external, may be connected to the system bus  121  via the input interface  160 , or other appropriate mechanism. In a networked environment, program modules depicted relative to the computer  110 , or portions thereof, may be stored in the remote memory storage device. By way of example, and not limitation,  FIG. 2  illustrates remote application programs  185  as residing on memory device  181 . 
     The communications connections  170   172  allow the device to communicate with other devices. The communications connections  170   172  are an example of communication media. The communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. A “modulated data signal” may be a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Computer readable media may include both storage media and communication media. 
       FIG. 3  depicts an exemplary peer-to-peer network, that may be similar to or coupled to the network  10  of  FIG. 1 . A peer-to-peer network  200  may have individual clouds  202   204   206  coupled by networks  208   210   212 . The networks may be wired or wireless and may support Internet protocol version 6 (IPv6). Cloud  202  may have computers  214   216 . Each computer may support multiple endpoints, for example, computer  216  is shown supporting endpoint  1   218  and endpoint  2   220 . Cloud  204  is shown having computers  222  and  224 . Computer  224  is shown supporting three endpoints  226   228  and  230 . Cloud  206  is shown having computers  232  and  234 . For the sake of this example, the computers of cloud  206  are not shown supporting any endpoints. In this exemplary embodiment, each computer and its associated endpoints are shown within their respective clouds  202   204   206 , indicating perhaps organization by network topology. 
     Each of the endpoints  218   220   226   228   230  may be processes, files, IP addresses, and the like. Each endpoint must be explicitly registered in order to be discovered on the peer-to-peer network  200 , within their respective clouds. For example, when one endpoint  218  wishes to register in cloud  202  it may use the PeerPNRPRegister call documented below. The PeerPNRPRegister call may be restricted to its own link-local cloud  202 . Similarly, an endpoint in cloud  204 , for example, endpoint  230 , may register locally in cloud  204  The PeerPNRPUpdateRegistration call may be used when data about the endpoint has changed, for example, an IP address. When an endpoint wishes to remove itself from the peer-to-peer network a PeerPNRPUnregister call may be issued. The methods by which peer-to-peer network registration information is propagated through a peer-to-peer network are known and well documented and are not discussed further here. 
       FIG. 4  represents a more complex embodiment of peer-to-peer networking. The peer-to-peer network  300  has clouds  302 ,  304  and  306 . The clouds may be coupled by respective network connections  308 ,  310 , and  312 . Computer  314  in cloud  302  may have one or more endpoints (not depicted). Computer  316  is outside any cloud but has endpoint  1   322  in cloud  302  and endpoint  2   324  in cloud  304 . The computer  316  configured in this manner may be attached to different points in a topologically organized network and may be able to publish different endpoints in different networks. 
     Computer  318  is shown in cloud  306  while computer  320  is shown configured in both clouds  304  and  306 . In this case, the computer  320  may be a logical member of both clouds  304  and  306 . It may publish the endpoint  326  in both clouds simultaneously. 
     Input and output information and structural documentation for registration-oriented calls follow. After registration, a handle may be returned for use in future calls regarding a particular endpoint having that handle. 
     Any call that returns endpoint data may return a null set, in other words, no data. This may be the case when the name registration data for a cloud or endpoint cannot be matched to an existing entity. In this case, the return with no data is significant and useful. 
     PeerPnrpRegister—This method is used to register a PNRP endpoint. The infrastructure will pick addresses in all clouds to register, and watch for address change events, re-registering as necessary. 
     Syntax 
                                               HRESULT WINAPI PeerPnrpRegister(             IN   PCWSTR   pcwzPeerName,        IN   PPEER_PNRP_REGISTRATION_INFO   pRegistrationInfo,        OUT   PHANDLE   phRegistration       );                    
Arguments
 
     
       
         
               
               
             
           
               
                   
               
               
                 pcwzPeerName 
                 Name to register 
               
               
                   
               
             
             
               
                 pRegInfo 
                 Optional information about the registration. NULL will 
               
               
                   
                 register all addresses in all clouds. See Notes. 
               
               
                 phRegistration 
                 Handle for the registration allowing for updates and 
               
               
                   
                 unregistration. 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
             
               
               
               
             
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 typedef struct peer_pnrp_register_info_tag { 
               
             
          
           
               
                   
                   PWSTR 
                  pwzCloudName; 
               
               
                   
                   ULONG 
                  cAddresses; 
               
               
                   
                   SOCKADDR 
                 **ppAddresses; 
               
               
                   
                   WORD 
                  wPort; 
               
               
                   
                   PWSTR 
                  pwzComment; 
               
               
                   
                   ULONG 
                  cbPayload; 
               
               
                   
                   PBYTE 
                  pbPayload; 
               
             
          
           
               
                   
                  } PEER_PNRP_REGISTER_INFO, 
               
               
                   
                 *PPEER_PNRP_REGISTER_INFO; 
               
               
                   
                   
               
             
          
         
       
     
     The PEER_PNRP_REGISTER_INFO provides additional information on how registrations should be performed. Conceptually, the simple mode for the API is passing null for this argument. Complex settings are accessed by actually using the structure. 
                                     pcwzCloudName   Name of the cloud in which to register the peername, typically retrieved via PeerPnrpGetCloudInfo.           Also understands the following special values:           * NULL: the peername will be registered in all clouds.           * PEER_PNRP_ALL_LINK_CLOUDS: the peername will be registered in all link local clouds           * PEER_PNRP_GLOBAL_CLOUD: the peername will only be registered in the global cloud.       cAddresses   Count of the number of addresses to be published. Max is 4. The value may be 0, only if a payload is           specified. cAddress may also be the special value PEER_PNRP_AUTO_ADDDRESSES, which will           cause the infrastructure to automatically choose good addresses for each specified cloud.       ppAddresses   Array of address/socket information that will be published with the name.       wPort   Only used when cAddress equals PEER_PNRP_AUTO_ADDRESSES. Specifies which port to           publish with the address chosen by our api. See further notes below.       pcwzComment   Comment field string for inclusion in CPA.       cbPayload   The byte count of the payload.       pbPayload   The payload information for the registration. Required if cAddress equals 0.                    
The pRegInfo in the call to PeerPnrpRegister may be NULL. This is equivalent to passing a PEER_PNRP_REGISTER_INFO with following values:
 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 pwzCloudName 
                 NULL (All clouds) 
               
               
                   
                 cAddresses 
                 PEER_PNRP_AUTO_ADDRESSES 
               
               
                   
                 ppAddresses 
                 NULL 
               
               
                   
                 wPort 
                 0 
               
               
                   
                 pwzComment 
                 NULL 
               
               
                   
                 cbPayload 
                 0 
               
               
                   
                 pbPayload 
                 NULL 
               
               
                   
                   
               
             
          
         
       
     
     When PEER_PNRP_AUTO_ADDRESSES is used (or NULL is passed the pRegInfo), not only does the API pick good values for addresses to register, but it keeps the registrations up to date. As new clouds come up, we will automatically register in them. If the addresses on the local machine change, current registrations will be updated with the new addresses. 
     PeerPnrpUpdateRegistration—This method is used to update a registration of a PNRP endpoint. 
     Syntax 
                                             HRESULT WINAPI PeerPnrpUpdateRegistration(           IN  HANDLE  hRegistration,           IN  PPEER_PNRP_REGISTRATION_INFO pRegistrationInfo);                        
Arguments
 
                                                 hRegistration   Handle to the registration from PeerPnrpRegister           pRegInfo   the updated registration info                        
Not all things about a registration may be changed. Specifically, the cloudname may not be changed, and cAddresses can not change between auto-selected addresses and specified addresses. The updated registration data may include data specifying one or more clouds and data about one or more address/socket information pairs, although for a given pair, the address or socket information may be null.
 
     PeerPnrpUnregister This method removes a PNRP endpoint registration 
     Syntax 
                                             VOID WINAPI PeerPnrpUnregister(             IN   HANDLE hRegistration           );                        
Arguments:
 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 phRegistration 
                 Handle to the registration from PeerPnrpRegister 
               
               
                   
               
             
          
         
       
     
     A participant in the peer-to-peer network  200  may wish to gather information about resources available on the peer-to-peer network, for example, other endpoints. The Simple PNRP API supports several calls for determining information about clouds and other endpoints. Cloud information may be returned by issuing a PeerPnrpGetCloud info call, as documented below. 
     PeerPnrpGetCloudInfo This method will retrieve all cloud names. 
     Syntax 
                                             HRESULT WINAPI PeerPnrpGetCloudInfo(             ULONG *pcNumClouds,             PPEER_PNRP_CLOUD_INFO *ppCloudInfo           );                        
Arguments
 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 pcNumClouds 
                 The number of cloud names pointed to by 
               
               
                   
                 ppwzCloudNames 
               
               
                 ppCloudInfo 
                 The cloud information. This param must be freed via 
               
               
                   
                 PeerFreeData. 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
             
               
             
           
               
                   
               
             
             
               
                 typedef struct peer_pnrp_cloud_info_tag 
               
               
                 { 
               
             
          
           
               
                   WCHAR 
                 wzCloudName[MAX_CLOUD_NAME]; 
               
               
                   DWORD 
                 dwScope; 
               
               
                   DWORD 
                 dwScopeId; 
               
             
          
           
               
                 } PEER_PNRP_CLOUD_INFO, *PPEER_PNRP_CLOUD_INFO; 
               
               
                   
               
             
          
         
       
     
     There are two options for retrieving information about endpoints in the peer-to-peer network. The first initiates processes associated with retrieving endpoints from peernames and associated data in a synchronous (blocking) manner and returns results when the resolve process is completed. A second option resolves endpoints in a two step process. The first step initiates the data gathering in an asynchronous (non-blocking) manner. In most cases, this asynchronous method may offer more utility by allowing other activities, including other peer-to-peer network activities to take place in parallel. The second step involves retrieving the specific endpoint data accumulated during the non-blocking resolve step. 
     The synchronous (blocking) call is documented below. 
     PeerPnrpResolve This method performs a synchronous (blocking) resolve. 
     Syntax 
                                                                     HRESULT WINAPI PeerPnrpResolve(                  IN PCWSTR    pcwzPeerName,             IN PCWSTR    pcwzCloudName  OPTIONAL,             IN OUT ULONG   *pcEndpoints,                  OUT PPEER_PNRP_ENDPOINT_INFO *ppEndPointInfo           );                        
Arguments
 
                                     pcwzPeerName   The name to be resolved.       pcwzCloudName   The cloudname to perform the resolve. If NULL,           resolves will be performed in all clouds. If           PEER_PNRP_ALL_LINK_CLOUDS,           resolves in all link local clouds. If           PEER_PNRP_GLOBAL_CLOUD,           resolve will only take place in the global cloud       pcEndpoints   On input, specifies the desired number of results.           On output, specifies the actual number pointed to by           ppEndpointInfo. Max is 500.       ppEndPointInfo   Returns an array of the resultant           PNRP_ENDPOINT_INFO           information. Must be freed by a call to PeerFreeData.                    
For non-blocking functionality, use PeerPnrpStartResolve. To use a specific timeout, use the asynchronous version.
 
If CloudName is null and the resolve is conducted in all clouds, then resolves will be issued in each cloud simultaneously. The method will return as soon as it has received enough results from any combination of clouds.
 
     The asynchronous (non-blocking) call and the related calls for stopping the resolve process and retrieving results when available are documented below. 
     PeerPnrpStartResolve This method performs an asynchronous (non-blocking) resolve. This is the recommended way of performing resolves, especially if multiple endpoints are desired. 
     Syntax 
                                                               HRESULT WINAPI PeerPnrpStartResolve(                  IN   PCWSTR   pcwzPeerName,             IN   PCWSTR   pcwzCloudName,             IN   ULONG   cMaxEndpoints,             IN   HANDLE   hEvent,             OUT   PHANDLE   phResolve,           );                        
Arguments
 
                                     pcwzPeerName   The name to be resolved.       pcwzCloudName   The cloud name to perform the resolve. If NULL,           resolves will be performed in all clouds.       cMaxEndpoints   The maximum number of endpoints to return to the           caller       hEvent   An event handle to signal when new resolves are ready           for consumption by calling PeerPnrpGetEndpoint       phResolve   Handle which can be used to cancel the resolve           via PeerPnrpStopResolve                    
As results are found, the hEvent gets signaled. The application may then call PeerPnrpGetEndpoint to retrieve the resolved Endpoint(s). In another embodiment, results may be returned via a callback to the requesting process.
 
     PeerPnrpStopResolve This method will cancel an in-progress resolve from a call to PeerPnrpStartResolve. 
     Syntax 
                                             VOID WINAPI PeerPnrpStopResolve(             IN HANDLE hResolve           );                        
Arguments
 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 hResolve 
                 The resolve handle from PeerPnrpStartResolve 
               
               
                   
                   
               
             
          
         
       
     
     When the process resolving the peer-to-peer network has enough data, data is made available about the endpoints. The data may then be retrieved in the second step using the PeerPnrpGetEndpoint call. 
     PeerPnrpGetEndpoint This method is used to retrieve endpoints from a previous call to PeerPnrpStartResolve. 
     Syntax 
                                                           HRESULT WINAPI PeerPnrpGetEndpoint(                  IN   HANDLE hResolve,             OUT   PPEER_PNRP_ENDPOINT_INFO *pEndpoint           );                        
Arguments
 
                                                 hResolve   The resolve handle from PeerPnrpStartResolve           pEndpoint   A single Endpoint which was resolvedas a               PeerPnrpEndpointInfo struct                        
Errors
 
                                     PEER_E_PENDING   The api was called before a resolve was ready       PEER_E_NO_MORE   No more endpoints are available,           this resolve is complete.                    
This method is part of the asynchronous resolve PnrpAPIs that also include PeerPnrpStartResolve and PeerPnrpStopResolve.
 
     The details of a structure used to contain data about a PNRP endpoint are documented below. 
     PeerPnrpEndpointInfo The main data structure used to contain a PNRP Endpoint. 
     Syntax 
                                                                                                     typedef struct peer_pnrp_endpoint_info_tag {                  PWSTR   pwzPeerId;             ULONG   cAddresses;                  PSOCKADDR   *   ppAddresses;                  ULONG   cbPayload;             PVOID   pPayload;                } PEER_PNRP_ENDPOINT_INFO,           *PPEER_PNRP_ENDPOINT_INFO;                        
Elements
 
     
       
         
               
               
             
           
               
                   
               
             
             
               
                 pwzPeerId 
                 The complete Peer ID of the Endpoint. 
               
               
                 cAddresses 
                 Number of address/port pairs associated with the Endpoint. 
               
               
                 pAddresses 
                 Array of address/port information that will be 
               
               
                   
                 published with the name 
               
               
                 cbPayload 
                 The byte count of the payload 
               
               
                 pPayload 
                 The payload information for the registration. 
               
               
                   
               
             
          
         
       
     
     Although the forgoing text sets forth a detailed description of numerous different embodiments of the invention, it should be understood that the scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possibly embodiment of the invention because describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the invention. 
     Thus, many modifications and variations may be made in the techniques and structures described and illustrated herein without departing from the spirit and scope of the present invention. Accordingly, it should be understood that the methods and apparatus described herein are illustrative only and are not limiting upon the scope of the invention.