Patent Publication Number: US-9408240-B2

Title: Method and system for communicating message notifications to mobile devices

Description:
FIELD OF THE INVENTION 
     This application is directed to methods and systems for communicating message notifications and, in particular, to methods and systems for communicating message notifications from a server to mobile devices. 
     BACKGROUND TO THE INVENTION 
     As known in the art, end-to-end communications in a telecommunications network (for example, between a client and server) are typically carried out via a transport mechanism. Data passed to the transport mechanism from one end system, such as a client, is relayed to the other end system, such as a server, via the underlying network infrastructure which remains largely transparent to the end systems. The client in mobile systems is typically resident in the mobile handset or device, while the server is typically resident at a fixed location, separated from the mobile handset by at least one wireless network and perhaps a plurality of ground networks. 
     In a network, the client/server model provides a convenient way to interconnect programs that are distributed efficiently across different locations. Typically in the usual client/server model, one server (sometimes called a daemon) is activated and awaits client requests. As a result, connections in the client/server model are established by the client requesting opening of a connection with the server. This causes difficulties in implementations such as mobile communications where, in order to allow for the use of devices with limited capabilities, many mobile devices are equipped to operate solely as clients. As a result, a data channel between client and server can only be initiated by the mobile device. 
     The communication model described above is a client-server model, which enables a client to set up a connection with the server. A limitation of the above-described communication model is that it does not allow the server to set up the connection with the client. In order to overcome this limitation, a mechanism known as a Communication Initiation Request (CIR) may be used. A CIR allows the server to inform the client that it should establish a communication channel, as per the previously described client-server model. 
     SUMMARY OF THE INVENTION 
     According to at least some example embodiments, there is a system and method for choosing between different CIR channels when there are multiple CIR channels amongst which to choose. 
     According to at least some example embodiments, there is a system and method for exploiting the usage pattern which is exhibited when TCP is being used as the sole or primary transport mechanism for CIR in order to significantly increase the number of concurrent TCP connections that a given server can support. 
     According to one example embodiment, there is a method for transmitting a CIR message from a server to a mobile client that supports a plurality of CIR channels. The method includes a CIR message transmission step during which a first of the plurality of CIR channels is selected, and an attempt is made to transmit the CIR message via the first selected CIR channel. If the CIR message cannot be transmitted by the first selected CIR channel, the channel selecting and transmission attempting are repeated using a second one of the plurality of CIR channels. 
     According to another example embodiment, there is a ground end system in a mobile communications system. A server runs on the ground end system and is in communication with at least one mobile client that supports a plurality of CIR channels. The server includes computer code for generating a CIR message. The server also includes computer code for selecting a first of the plurality of CIR channels. The server additionally includes computer code for attempting to transmit the CIR message via the first selected CIR channel. The server also includes computer code for repeating execution of the selecting code and the transmission attempt code, but for a second one of the plurality of CIR channels, the repeated execution code being employed if the CIR message cannot be transmitted by the first selected CIR channel. 
     According to yet another example embodiment, there is a method for establishing and maintaining a TCP connection for the transmission of messages between a server and client. The method includes the step of providing, in the server, a conventional server of TCP connections (CCS) and a slow server of TCP connections (SCS). The method also includes the step of receiving a connection request at the server, from the client. The method additionally includes the step of establishing a TCP connection between the client and the CCS. The method also includes the step of transferring the established connection to the SCS in the server, wherein the SCS receives the messages. 
     According to yet another example embodiment, there is a ground end system in a mobile communications system. A server runs on the ground end system and is in communication with at least one mobile client. The server includes a conventional server of TCP connections (CCS), a slow server of TCP connections (SCS), and computer code for receiving and processing a connection request from the mobile client at the server. The server also includes computer code for establishing a TCP connection between the mobile client and the CCS. The server additionally includes computer code for having assignment of the established connection changed from the CCS to the SCS. The SCS receives messages from the mobile client when the SCS is handling the established connection. 
     According to yet another example embodiment, there is a method for establishing and maintaining a TCP connection for the transmission of messages between a server and client. A conventional connection server and a slow connection server are provided in the server. A connection request is received at the server, from the client, and then a connection is established between the client and the conventional connection server. On expiration of a predetermined inactivity period, the established connection is reassigned to the slow connection server. On reception of a message transferred from the client, the established connection is reassigned back to the conventional connection server if the established connection has been assigned to the slow connection server, and then the message is received at the conventional connection server from the client. On reception of a message for transfer to the client, the established connection is reassigned back to the conventional connection server if the established connection has been assigned to the slow connection server, and then the message is transmitted from the conventional connection server to the client. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made, by way of example, to the accompanying drawings: 
         FIG. 1  shows a schematic diagram of a mobile communications system to which embodiments of the present invention can be applied; 
         FIG. 2  shows a conceptual model of client-server communications; 
         FIG. 3  shows, in diagrammatic form, client polling in HTTP binding for CIR channel when the server does not have any queued requests or responses; 
         FIG. 4  shows, in diagrammatic form, client polling in HTTP binding for CIR channel when the server has queued requests or responses; 
         FIG. 5  is a flow chart of a method for selecting a Communication Initiation Request (CIR) channel in accordance with an illustrative embodiment of the present invention; 
         FIG. 6  shows, in diagrammatic form, the use of TCP protocol by the OMA IMPS Standard in accordance with an illustrative embodiment of the present invention; 
         FIG. 7  is a flow chart of a TCP CIR channel monitoring process in accordance with an illustrative embodiment of the present invention; and 
         FIG. 8  is a flow chart of a TCP CIR channel monitoring process in accordance with an alternative illustrative embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS 
     Referring now to  FIG. 1 , an illustrative embodiment of a mobile communications system, generally referred to using the reference numeral  10  will now be described. The system  10  is comprised of one or more ground end systems  12  comprised of a server  14  and a plurality of mobile end systems  16  (for example, a cellular phone, PDA enabled for wireless communication, or other wirelessly enabled mobile device) each comprised of at least one client  18 . The ground end systems  12  and the mobile end systems  16  are interconnected by at least one wireless Radio Frequency (RF) network  20  and typically a plurality of interconnected ground networks as in  22 . In order to gain access to the wireless RF network  20 , each mobile end system  16  is equipped with an antenna  24 , and as a result is able to relay data and eventually other communications signals to a second antenna  26  attached to the ground network(s)  22 . 
     Still referring to  FIG. 1 , the server  14  and client  18  are typically software applications running on their respective end systems  12 ,  16  which take advantage of the wireless RF network  20  and interconnected ground networks as in  22  to communicate with one another. Referring now to  FIG. 2 , each server as in  14  or client as in  18  typically has access to the underlying communications networks  20 ,  22  via protocol stacks as in  28 ,  30 . As known in the art, use of such protocol stacks as in  28 ,  30  (also known as a “layered architecture”) provide distinct advantages in terms of transparency, interoperability and expandability. Each of the protocol stacks as in  28 ,  30  is divided into a plurality of layers as in  32 . Although a protocol stack can have many layers, in order to provide “end to end” communications, such as those provided by the TCP/IP model, four layers are used with the upper most, or transport, layer as in  34 ,  36  being the only layer typically accessible by the either the server  14  or client  18 . Additionally, as known in the art, a client  18  wishing to establish a connection with a server  14  requests this establishment from its respective transport layer  36  using one or more predefined commands typically referred to as primitives. Based on the information provided in the primitives, the transport layer  36  communicates with its peer transport layer  34  and establishes a logical path  38  through which data can flow, thereby allowing the client  18  to communicate with the server  14  and vice versa. 
     As will be appreciated by those skilled in the art, additional known network devices, such as routers  40  or the like, may be needed to support communication between a particular pair of peer transports layers as in  34 ,  36 . 
     As previously discussed, data communications between the server  14  and the client  18  are typically initiated by the client  18 . However, for some applications such as, for example, Instant Messaging, the server  14  may wish to establish communications with the client  18 . 
     In the Open Mobile Alliance (OMA) Instant Message and Presence Service (IMPS) Standard, which is a standard that has been developed taking the above-mentioned issue into account and which was formerly known as the Wireless Village (WV) Standard, the transport binding is logically divided into two channels. One of these two channels is a bidirectional data channel via which the exchange of Client-Server Protocol (CSP) primitives between client and server is carried out. As will be appreciated by one skilled in the art, possible protocol bindings in the data channel include, for example, WSP, HTTP, HTTPS and SMS. The second of these two channels is a unidirectional CIR channel from server to client which is used to activate the data channel whenever the data channel is not established, or the event communication has been halted in the data channel and needs to be reactivated. As will be later described, a variety of transport mechanisms/methods have been proposed for the CIR Channel such as: Wireless Application Protocol (WAP) push over Short Message Service (SMS), WAP push over User Datagram Protocol/Internet Protocol (UDP/IP), Standalone SMS, Standalone UDP/IP, Standalone Transmission Control Protocol/Internet Protocol (TCP/IP), Standalone Hypertext Transfer Protocol 
     Thus, the OMA IMPS Standard provides for a dedicated CIR channel  42  between the server  14  and the client  18  that in at least some example embodiments is reserved solely for the transfer of CIRs. This dedicated channel may be implemented in a number of different ways depending on the capabilities of the server  14  and, in particular, the client  18  running on, for example, the processor of the end system  16 . 
     For example, if the server  14  and client  18  support TCP/IP, the dedicated CIR channel  42  can be provided by a dedicated TCP/IP connection between peer transport layers  34 ,  36 . This TCP/IP connection would typically be set up during a login procedure and remain alive for as long as a data path is available between the client  14  and server  18 . Alternatively, if UDP is supported, UDP can be used to provide the dedicated CIR channel. A similar case arises with both SMS and HTTP which both can be used to provide the dedicated CIR channel in particular implementations. Similarly, on a WAP equipped mobile device WAP push over SMS or UDP/IP as bearer can be used, again depending on the capabilities of the mobile device. 
     As discussed above, in the OMA IMPS Standard the capabilities of the client  18  and server  14  are exchanged during client-server negotiation during, for example, the login procedure, and part of the information exchanged includes CIR capabilities. This gives an indication to the server  14  which CIR channels are supported by the client  18 , and an indication to the client  18  which CIR channels may be used by the server  18 . While in some examples the server  14  receives notice from the client  18  during client-server negotiation of the plurality of CIR channels supported by the client  18 , in at least one other alternative example the server  14  maintains a CIR capability table that indicates what CIRs a particular client  18  supports. When the client  18  logs in, it identifies itself through a clientId provided during the login transaction. This clientId is then used by the server  14  as a handle to fetch from the CIR capability table the particular CIRs supported by that client. In still other alternative examples, the server  14  expects that the client  18  will support all of the CIR channels within a default set of CIR channels. 
     As previously mentioned, the OMA IMPS Standard indicates that there are a number of possible transport bindings for supporting the CIR channel, such as: WAP push binding (WAP push over SMS as bearer or WAP push over UDP/IP as bearer), Standalone SMS binding, Standalone UDP/IP binding, Standalone TCP/IP binding, Standalone HTTP binding. 
     With respect to WAP push binding, WSP push messages are sent from the server  14 . If the server  14  is provisioned with an address of the WAP Push Proxy Gateway (PPG) and supports WAP Push Access Protocol (PAP), it can initiate a WAP Push request. To send a CIR to the mobile end system  16 , the server  14  can use the push submission operation. In at least some examples, each push message contains a single CIR. Content type (as registered with Internet Assigned Numbers Authority) of the content entity of a Push Access Protocol request is “application/vnd.wv.csp.cir”. 
     The use of WAP Push does not require that the client  18  have active PDP context. (PDP context, as will be appreciated by those skilled in the art, is a data structure containing particular session information.) In some examples, the PPG uses an SMS bearer to send the initiation request. Alternatively, if a PDP context is already active and the Internet Protocol (IP) address is known, the PPG can push the message over TCP or UDP. 
     Still with reference to WAP push binding, in those examples where the client  18  is in a mobile handset, the mobile number may be provided in the CSP protocol login transaction (as a part of Client ID). If the mobile number is not present, the Service Access Point (SAP) will obtain the mobile number if it is required. Also, it will be understood that if the Mobile Station International Subscriber Directory Number (MSISDN) is available between sessions, offline notification is possible. In the case of offline notification therefore, the MSISDN, received via the login transaction may be cached between sessions or, alternatively, the SAP may obtain the mobile number if it is required. 
     With respect to Standalone SMS Binding, the CIR channel is facilitated by, for example, Global System for Mobile Communications (GSM) short message or Code Division Multiple Access (CDMA) IS-637 short message technology. Also, in Standalone SMS Binding, both the client  18  and the Short Message Service Center (i.e., network element which delivers SMS messages) will support both Mobile-Originated (MO) and Mobile-Terminated (MT) short messages. 
     In at least some examples, Standalone SMS binding will support both GSM SMS [TS 23.040] and CDMA SMS IS-637 [TIAEIA-637]. The encoding of SMS messages for CIR can be the GSM 7-bit default alphabet defined in [TS 23.038]. In at least some examples, each SMS message contains a single CIR. 
     With respect to Standalone UDP/IP binding, the server  14  sends the client  18  the CIR messages enclosed in UDP datagrams. In at least some examples, each UDP datagram contains a single CIR message and the client  18  is capable of receiving UDP datagrams directly from the server  14 . Due to the small size of the CIR message, the UDP datagram will not be fragmented or rejected because of size. 
     The client  18  may, for example, accept the CIR request to a default UDP port. Alternatively, the client  18  may, for example, provide the UDP port in the capability negotiation phase of client login. 
     Still with reference to Standalone UDP/IP binding, it may be more convenient (due to the behavior of some NAT routers) if whenever the server  14  sends a message to the client  18 , the server  14  uses the same IP and port used by the client  18  as the destination address. In at least some examples, this will be the same address as appeared in the ClientCapabilityResponse to the ClientCapabilityRequest (for setting up the communication preferences for the session). 
     With respect to Standalone TCP/IP binding, there is a persistent connection from the client  18  to server  14  to provide a low-latency always-on CIR channel. As will be appreciated by those skilled in the art, TCP may be more easily usable in certain mobile networks than other Internet Protocols such as User Datagram Protocol (UDP) due, for instance, to security measures implemented in firewalls and other network elements. For these reasons, certain mobile devices support only TCP for CIR. 
     The TCP CIR channel is a push-type connection-oriented channel, the primary purpose of which is to carry CIRs from the server  14  to the client  18 . Once established, a TCP CIR connection serves two purposes: to convey CIRs from the server  14  to the client  18  and to verify that the connection is still alive. 
     The client  18  is responsible for setting up the TCP/IP connection and maintaining its persistency. The client  18  can open the CIR TCP/IP connection to the server  14  right after a successful login procedure including client capability and service negotiation. The IP address and port for the CIR channel can be provided by the server  14  in the capability negotiation. In at least some examples, the IP address and port are valid throughout the session. 
     Still with reference to Standalone TCP/IP binding, when a server  14  has any data (CSP request or response) that needs to be sent to the client  18 , it sends a CIR message over the TCP/IP connection associated with this client. (Typically, all client and server originated messages will be terminated with a &lt;CR&gt;&lt;LF&gt; (carriage return, line feed) sequence, the character-encoding scheme will be UTF-8, and the minimum supported set of characters will be ISO-8859-1 (Latin 1).) 
     With respect to Standalone HTTP binding as illustrated in  FIGS. 3 and 4 , the client  18  periodically polls on the CIR channel for a CIR trigger. When a CIR trigger is received, the client  18  sends a CSP PollingRequest  140  ( FIG. 4 ) to enable the server-initiated transaction including server insertion of a transaction request into the response part of the poll request. In at least some examples of other CIR channels, the server-initiated transaction is enabled in the same manner. 
     One skilled in the art will appreciate that polling is very resource consuming when it comes to bandwidth and server load. Hence, the polling overhead is reduced, in at least some examples, by having periodic polling only done for CIR with a minimal HTTP GET on a non-persistent HTTP connection. 
     The URL to be used for the CIR poll can, for example, be provided by the server  14  in the capability negotiation (reference numeral  144  in  FIGS. 3 and 4 ). The format of the address is such that the server  14  can identify the session; however for security reasons it may be preferable that the actual Session is not revealed in the HTTP binding. An example format of a poll URL is: MyServiceProvider.com/poll?pc=1234567 (The ‘pc=1234567’ is an example poll cookie that the server  14  generates and internally uses to map to the real session.) The URL is valid throughout the session, and it will be understood that the client  18  closes the HTTP connection after each poll. 
     Still with reference to the above-described Standalone HTTP binding, the client  18  is responsible for setting up the HTTP connection and doing the polling. The minimum time between two polls can be given by the server  14  during client capability negotiation. The client  18  starts to poll after it successfully logs in and has completed appropriate client capability and service negotiation. 
     In the presently described examples, the Client  18  uses the HTTP GET method to poll on the HTTP binding. (This is illustrated in  FIGS. 3 and 4  by a directional arrow  150  between the client  18  and MyServer.com node  152 ). If there are no queued CSP messages on the server  14 , the server  14  replies (in at least some examples) with ‘204 No Content’ (as shown by directional arrow  154  in  FIG. 3 ). If CSP messages are queued on the server  14 , the server  14  replies (in at least some examples) with a ‘200 OK’ (as shown by directional arrow  158  in  FIG. 4 ). The reply substitutes for the textual CIR message that is used in other CIR channel bindings. If ‘200 OK’ is received, the client  18  then performs a CSP Polling Request transaction to retrieve the server-initiated transaction. As shown in  FIG. 4 , in response to the client  18  sending a CSP PollingRequest  140  to the server  14 , the server  14  sends a CSP Primitive to the client  18  on the data channel (as shown by directional arrow  162 ). 
     In some examples, the client  18  implements an adaptive polling policy. For instance, when polling requests return a CIR trigger to do a CSP PollingRequest Transaction, the client  18  will normally initiate the next polling request after some minimum interval. However, in the case of empty responses, the polling intervals can be gradually increased (for example, up to 10 seconds or more). 
     In at least some examples, HTTP binding is used by clients that cannot establish any other CIR channel. 
     Having described various example transport bindings for supporting the CIR channel, it will of course be understood that there are different trade-offs to consider when choosing a particular CIR channel/method, including latency of a particular method, cost for a particular network, or features supported by the mobile handset or device. 
     Also, at the beginning of the session (for example, during a negotiation portion of login) the client  18 , in some examples, supplies the server  14  with a list of supported CIR channels or methods. The server  18  may choose to use only a particular CIR channel for the duration of the session. However, using only a particular CIR channel or method may not take advantage of the redundancy or other advantages supported by the simultaneous use of a plurality of different CIR channels. In order to do this, a dynamic selection of the CIR channel to be used during a session is provided for in at least one example embodiment. 
     An example of a method for allowing the server  14  to choose a CIR channel during a session is shown in  FIG. 5 , and the illustrated method will be generally referred to herein using the reference numeral  200 . Beginning at start step  202 , when the server has a CIR to send to the client  18 , the server  14  is configured to first determine if the preferred method of sending the CIR is supported by the client  18  and the mobile handset or device. In the illustrated example, the preferred method is UDP, and therefore at example step  204  the server  14  determines whether or not there is support for UDP or WAP Push over UDP as CIR. If there is no such support, the next step is step  206  where the server  14  determines whether or not there is support for the next alternative (which in the case of the illustrated example is TCP as CIR). If however it is determined at the step  204  that there is support for UDP or WAP Push over UDP as CIR, the next step is step  208  where an attempt is made to use the CIR channel. As will be appreciated by those skilled in the art, the CIR channel with respect to which the first attempt is made may not be usable (for example, due to a connection that is not established or the like) and therefore a check is carried out at step  210  as to whether the CIR was sent successfully. If the chosen CIR channel is successful, the illustrated process ends at end step  224 . If the first CIR channel chosen is not successful, the step  206  follows (see above). 
     Still with reference to the method  200 , if at the step  206  it is determined that there is no support for TCP as CIR, the next step is step  212  where the server  14  determines whether or not there is support for the next alternative (which in the case of the illustrated example is SMS or WAP Push over SMS as CIR). If however it is determined at the step  206  that there is support for TCP as CIR, the next step is step  214  where an attempt is made to use the CIR channel. As previously discussed, the CIR channel with respect to which the attempt is made may not be usable for some reason, and therefore a check is carried out at step  216  as to whether the CIR was sent successfully. If there was success, the illustrated process ends at the end step  224 . If there was failure, the step  212  follows (see above). 
     Continuing on with the description of the illustrated method  200 , if at the step  212  it is determined that there is no support for SMS or WAP Push over SMS as CIR, the next step is step  218  where HTTP binding for CIR channel is set as the CIR channel. (It will be understood that HTTP binding for CIR channel is the last CIR channel alternative in the illustrated method  200 , and that the step  218  being carried out means that channel attempts have been made for all of the CIR channels that were indicated as being supported.) If however it is determined at the step  212  that there is support for SMS or WAP Push over SMS as CIR, the next step is step  220  where an attempt is made to use the CIR channel. As previously discussed, the CIR channel with respect to which the attempt is made may not be usable for some reason, and therefore a check is carried out at step  222  as to whether the CIR was sent successfully. If there was success, the illustrated process ends at the end step  224 . If there was failure, the step  218  follows (see above), after which is the end step  224 , and then the server waits for the client to poll using HTTP. 
     It will be understood that the order of selecting the CIR channel as shown in  FIG. 5  is only illustrative and is not intended to otherwise limit the manner in which a CIR channel may be selected. The order in which the CIR channels are attempted is configurable per deployment, as different networks may have conditions that prioritize differently the selection of one method over another. 
     In the event that a client  18  has available CIR channels based on both SMS and TCP/IP, the following method of selecting between them may be used between the client  18  and server  14 . This method ensures that the network is used efficiently for CIR and that the user has minimal delays in receiving messages while using the application. 
     When the user opens an application requiring a CIR channel, for example an Instant Messaging application or the like, the client  18  sets up a dedicated TCP/IP CIR channel. This CIR channel is maintained for a period of time, typically for at least as long as the user is using the application, although it should be noted that a user can be logged onto the server  14  without the application actively running on the handset. If the user shuts down the application, or the application is automatically closed, the TCP-CIR channel is closed by the client  18 . If the server  14  has detected that a CIR must be sent to the client  18 , it tries first to use the TCP-CIR channel. If there is no TCP-CIR channel established, the server  18  sends the CIR using the SMS CIR channel. When the mobile handset or device receives the CIR via SMS, if the mobile handset or device is capable of launching the application, the application (for example, an Instant Messaging client) is then started, and a TCP CIR channel is established. In this manner, the SMS CIR channel may be used to “wake-up” both the application and the TCP CIR channel. Note that typically SMS would only be used if the application in question was not running and no TCP CIR channel is available. 
     The OMA IMPS Standard provides no mechanism for allowing the client to indicate its preference of CIR channels to use. Additionally, in the case of particular limitation(s) or preference(s) in the mobile device or client in terms of supported CIR channels there is no way to signal this to the server. An example of this is if the client prefers to use a TCP CIR channel even though an SMS CIR channel is also available. To allow for the client  18  to indicate its preference to the server  14 , when the client  18  provides the list of supported CIR channels to the server  14  during negotiation, the client  18 , in some examples, additionally indicates a preferred order in which the server  14  should attempt to use these CIR channels. 
     In some examples, an order list providing the preferred order as described above will be stored (pre-negotiation) on the client  18 . In additional examples, the order list could be stored (pre-negotiation) on the server  14  and indicate the preferred channels for the server  14  (instead of the client&#39;s preferred channels). In further additional examples, there could be order lists stored both on the server  14  and the client  18 , and weighting could be used to generate a third order list that would be a best match of the preferences of both the client  18  and the server  14 . 
     Dynamic changing of the order list is envisioned: for example, in response to detection that a server-provisioned address of a WAP PPG has become invalid, any WAP push binding options in the order list might be removed from the order list (or, for example, moved to the bottom of the order list). As another example, the same modification of the order list might be carried out if the SAP cannot obtain an MSISDN that it needs. As yet another example, there might be, for example, detection that a client-provided UDP port is invalid, and the dynamic change in this case might be, for example, deleting the WAP push over UDP/IP and Standalone UDP/IP options from the order list (or, for example, moving these options down to the bottom of the order list). As yet another example, system security settings might change such that the client  18  is prevented from storing the poll cookie so as to possibly prevent Standalone HTTP binding, and therefore the dynamic change in this case might be removal of the Standalone HTTP binding option from the order list. 
     As mentioned previously, the communication model used in the OMA IMPS Standard uses two channels: a mandatory data channel in which the exchange of data is carried out, and an optional CIR channel which serves to activate the data channel when it is not established and data needs to be communicated. 
     Thus CIR channel usage and data channel usage are quite different, and usage of an example CIR channel is shown in  FIG. 6  and described below. It will be noted that although  FIG. 6  shows a CIR channel for a Standalone TCP/IP binding example, other types of CIR channel bindings are also comparatively described below, more than one of which are characterized by similar message traffic. 
     CIR establishment (reference numeral  225  in  FIG. 6 ): This is the initial phase during which the client and server establish the TCP CIR channel. The procedure is as described below. 
     (1) As the illustrated initial step, the client  18  initiates the TCP connection to provide a TCP CIR channel between client  18  and server  14 . 
     (2) Next, the server  14  responds to the client  18  by establishing the TCP connection. (It should be noted that there may be connection establishment issues if the client  18  is behind a firewall or proxy, and technology alternatives to facilitate the connection initiation and management include HTTP Tunneling [TCPTunnel], SOCK 4  and SOCK 5 .) 
     (3) Immediately upon receiving the response from the server  14  confirming that the TCP connection has been established, the client  18  sends the authentication message “HELO” with the Session ID as a parameter. This allows the server  14  to associate the new TCP/IP connection with one of the existing sessions. If the server  14  does not receive a “HELO” message within a pre-determined period of time (for example, 10 seconds) after a new connection has been opened from the client  18 , or if the received Session ID is unknown, the server  14  will terminate the connection. 
     In Standalone SMS Binding by comparison, the client  18  sends an SMS to the server  14  comprising the message “HELO” (GSM 7-bit default alphabet [TS 23.038] encoded, for example) with the Session-ID as a parameter. The SMS carrying the “HELO” message allows the server  14  to discover the mobile number of the client  18 . Caching between sessions of the MSISDN received via the “HELO” message may permit offline notifications. 
     In Standalone UDP/IP binding by comparison, the client  18  sends a UDP/IP packet to the server  14  comprising the message “HELO” with the Session-ID as a parameter. The packet carrying the “HELO” message allows the server  14  to discover the IP address of the client  18  and to overcome possible NATs. In at least some examples, the HELO message is sent to the IP and port set by the server  14  in the ClientCapabilityResponse message. 
     (4) Upon receiving the “HELO” message from the client, the server replies to the client with an “OK” message, and also a communication initiation request message [not explicitly shown] having parameters to provide additional information needed, at which point the TCP CIR channel is established. 
     In Standalone UDP/IP, the server  14  also replies to the “HELO” message of the client  18  with an “OK” message and the communication initiation request message. 
     CIR usage (reference numeral  226  in  FIG. 6 ): This is the phase during which the client  18  and server  14  use the CIR channel, and starts once the CIR channel has been established. During this phase, the TCP CIR channel is used for either of two purposes as described below. 
     First purpose: communication of CIR messages (directional arrow  227  illustrates the sending of a CIR message from the server  14  to the client  18 ). (1) The server  14  communicates a CIR when it wants to notify the client  18  that it should poll the server; and (2) the client  18  does not respond to the CIR over the TCP CIR channel. Rather, the client  18  is then expected to originate a PollingRequest message over the data channel (note that the PollingRequest message is not directly relevant for purpose of the TCP CIR channel discussion, and is only outlined here to facilitate a better understanding of the role of the CIR channel and the data channel in the OMA IMPS Standard). 
     Second purpose: Keepalive (reference numeral  228  in  FIG. 6 ). It is possible that the TCP CIR channel may be closed, for example if it has been inactive for a long duration or due to network problems. To prevent this from happening or to be able to recover, the client  18  illustratively implements a Keepalive mechanism enabling it to verify periodically a TCP CIR channel to the server  14  is still open. This mechanism is as follows: (1) The client  18  sends a “PING” message over the TCP CIR channel; (2) the server  14  responds to the “PING” message with the “OK” message; and (3) if a delay of several seconds (for example, thirty seconds) between sending a “PING” and receiving a corresponding “OK” expires, the TCP CIR channel is re-established, for example using the method as described hereinabove. 
     In the context of UDP/IP binding by comparison, it will be understood that the public address of the client  18  may, in some cases, be changed (i.e., by a NAT application) and by that not allow the server  14  to communicate with the client  18 . To prevent this from happening, the client  18  can periodically send “PING” messages over UDP/IP to maintain its address. The server  14  responds to these messages with the “OK” message. If the client  18  does not receive an “OK” message within a pre-established period of time, it sends the “HELO” message again. Since the IP address assigned to the client  18  may also change due to network considerations (for example, by GGSN or PDSN), the PING message also contains the session ID, similar to the HELO message. In this case, the server  14  is able to identify the PING, even if the IP address has changed and update its routing table accordingly. 
     CIR teardown (reference numeral  229  in  FIG. 6 ): This is the closing phase during which the client or the server closes the TCP connection. 
     The CIR establishment and teardown phases are relatively short. However, it is important to note that the TCP CIR channel makes particular uses of the TCP protocol during the CIR usage phase, notably: (1) Once the TCP CIR is established, the CIR channel may be held up for a very long duration, on the order of several hours or days; (2) the transactions carried over the TCP CIR connection are very short, for example, the exchange of one or two messages, and are infrequent; (3) three specific messages may be exchanged (“PING” from the client to the server, and “CIR” and “OK” from the server to the client); (4) the three messages are relatively short, and can be transmitted within single TCP socket read/write operations; and (5) the client can tolerate a delay of several seconds between initiating a message and receiving its response (for example, 30 seconds). 
     Within the historical context of fixed ground networks within which existed TCP&#39;s primary use, it was common for servers implementing TCP methods and best practices to have been developed under the assumption that the usage pattern of TCP is driven by Internet-type services such as web browsing using HTTP over TCP. In this type of usage, each TCP connection is set up for a short duration, during which it is intensely used. Typically, a given server in such an environment will have a capacity of approximately 10,000 concurrent TCP connections. However, in a mobile environment, the use of TCP as a single CIR requires each mobile handset or device to open the TCP connection to the server, and then requires the mobile handset or device and the server to maintain the TCP connection established for a duration that may be extremely long, on the order of several hours or days. During the time which the TCP connection is established, the connection is largely dormant, except for short periods of activity. When a large number of mobile devices using only TCP for CIR are deployed, the server is required to support a very large number of concurrent TCP connections. This is an atypical usage of TCP connections, which are usually kept open only for a short duration while there is a transfer of data ongoing and then closed. Keeping such long duration TCP connections open requires management both on the mobile device and on the server side. 
     In accordance with at least one example embodiment, a method as described below implements a two-state process for each TCP CIR channel between the server  14  and one of the pluralities of clients  18  to establish and maintain the TCP CIR channels. In a first state, the TCP CIR channel is established. In a second state, the TCP CIR channel is monitored to detect and serve incoming or outgoing messages. This monitoring exploits the specific use of the TCP protocol for TCP CIR channel purposes. 
       FIG. 7  depicts the two-state process in accordance with some examples, and the illustrated method will be generally referred to herein using the reference numeral  230 , which begins at start step  232  upon a request for a TCP CIR channel by the client  18  being received by the server  14 . Next at step  234 , the request is received by a Conventional Connection Server (CCS) for initial service. It will be understood that the CCS acts as a conventional socket server and waits for new connections by listening to a well-known TCP port. 
     The server  14  responds to the client  18 , providing the port that has been assigned to the client  18 . The client  18  receives the message from the server  14 , and replies with the “HELO” message. When the CCS receives the “HELO” message at step  240 , it (i) replies to the client with the “OK” message; and (ii) moves the connection from the NewConnectionList to the SlowConnectionList (step  242 ). At this point, the TCP CIR channel is established and the process transits from state  1  (TCP CIR channel establishment by the CCS) to state  2  (TCP CIR channel monitoring by the Slow Connection Server). 
     In state two, the Slow Connection Server (SCS) handles the TCP CIR channel. The SCS carries out at least one main activity: (1) for incoming messages, detecting the arrival of “PING” messages, and subsequently replying with “OK” messages. 
     With reference again to  FIG. 7 , a determination is made at step  244  as to whether the CCS needs to transmit a CIR to the client  18 . If yes, temporary state transitioning occurs so that the CCS can transmit the CIR to the client  18  at step  246 , and then the SCS returns to standby (i.e. the step  244 ) after SCS to CCS, and back to SCS state transitions. If no, the SCS stays in standby for a configurable wait time X for periodic inspection of the socket for the port assigned to the channel has not yet elapsed (step  248 ). (Wait time X can be any suitable wait time such as, for example, 5 to 10 seconds.) If wait time X has elapsed, decision step  250  is next in which the SCS first inspects the socket for the port assigned to the channel. If it is discovered that a “PING” message has been received, temporary state transitioning occurs so that the CCS can reply to the client  18  with an “OK” message. After the step  252 , the SCS returns to standby (i.e. the step  244 ) after SCS to CCS, and back to SCS state transitions. Alternatively, if the “PING” message has not been received, the SCS simply returns to standby (i.e. the step  244 ). 
     It will be understood that a disconnect event may occur while the TCP CIR channel is being monitored by the SCS. Possible disconnect events include, for example, detection that the client  18  has closed the connection or receipt of a request from the server  14  for the SCS to close the TCP CIR channel. (As an additional note, one skilled in the art will appreciate that, in at least one example, the server  14  can notify the client  18  that a CIR channel is disconnected by setting a CIR flag “F” in an http POST response.) The occurrence of the disconnect event leads to end step  254  in the method  230 . 
     In addition to the two-state process described above, the approach may be extended to situations in which TCP connections are established and maintained between a mobile device and a server for a very long duration, and during which the connections are used only sporadically while they are established. The TCP CIR channel is one specific occurrence of this usage pattern. However, the usage pattern matches other types of employments of TCP connections, the usage pattern being characterized by: (1) An initial period during which there is activity to set up the TCP connection, and to make an initial use of it, the initial use justifying the establishment of the connection and wherein the initial period of activity is of a short duration compared to the overall duration of the connection; (2) a subsequent period of long duration during which the TCP connection is dormant (meaning that no messages are exchanged), except for short periods during which there is activity (meaning exchange of messages); (3) a final period of short duration during which the TCP connection is closed; and (4) clients that can tolerate a delay of several seconds between initiating a message and receiving its response. 
       FIG. 8  illustrates a TCP connection method  260  in accordance with an example embodiment. The method  260  implements a two-state process similar to the previously described process in relation to the TCP CIR channel example. However, as opposed to the preceding section where the process progresses from state  1  to state  2 , the process here oscillates between states  1  and  2  as a function of the activity of the TCP connection. 
     The method  260  begins at start step  262  upon a client request for a TCP connection being received by the server. Next at step  264 , the request is received by a CCS for initial service. Following the step  264 , a TCP connection is established between the client and the server (steps  266 ) and once established, the connection is put in the ActiveConnectionList (it will be understood that the connection remains in the ActiveConnectionList, and thus in state  1 , for as long as it is being actively used). Next at step  268 , the CCS is kept in standby mode, in that it awaits either of (i) activity on the TCP connection which brings about CCS response step(s)  269 ; or (ii) the elapse of an inactivity period as described below. 
     If the initial activity period happens to elapse, the connection becomes inactive (dormant). This event is, for example, detected by the CCS through the inactivity period exceeding a configurable inactivity threshold. Upon occurrence of this event, management of the connection is moved to the SCS, thereby proceeding from state  1  to state  2 . In  FIG. 8 , the transition from state  1  to state  2  is illustrated by a transition arrow between the step  268  and step  270 . Upon occurrence of the transition from state  1  to state  2 , the connection is then reassigned from the ActiveConnectionList to the SlowConnectionList. (In at least one example embodiment, carrying this out involves removing a port number associated with the connection from the ActiveConnectionList, and then adding that port number to the SlowConnectionList) 
     Similarly as described before, the SCS, in at least some examples, carries out the following activities: (1) monitoring server-side initiated activity on the connection, triggering an outgoing data transmission (for example, message) to be sent from the server to the client; and (2) monitoring client-side initiated activity on the connection, triggering an incoming data transmission (for example, message) to be fetched. With respect to monitoring of client-side initiated activity, the SCS periodically inspects the socket for the port assigned to the connection (step  272 ) to detect any new incoming data transmissions (for example, new message(s) from the client). This period (referred to as “X seconds” in  FIG. 8 ) is configurable and can be of several seconds (for example, X=5 to 10 seconds). 
     When the SCS detects activity, either incoming (at the step  272 ) or outgoing, it declares that the connection has become active again. The connection is then reassigned from the SlowConnectionList to the ActiveConnectionList. (It will be understood that in some examples this reassignment is carried out by the SCS.) The process then moves back to state  1 , and the TCP activity is handled by the CCS. Both the transition arrow between the step  272  and the step  268 , and the transition arrow between the step  270  and the step  268  illustrate alternatives moves of the process from state  2  back to state  1 . 
     When the period of activity expires again, the client once again becomes inactive. This process will typically repeat itself on an ongoing basis as the client becomes active and inactive. If a particular connection is assigned to the ActiveConnectionList, that connection&#39;s data traffic will be handled with a faster response time because the associated port for the connection will be scanned at a higher frequency. Likewise, if a particular connection is assigned to the SlowConnectionList, that connection&#39;s data traffic will be handled with a slower response time because the associated port for the connection will be scanned at a lower frequency. 
     In some examples, the state transition causing inactivity event is detected by an inactivity timer. In such examples, the inactivity timer reassigns the connection back to the SCS. In other examples, the inactivity event will be detected by some other means (for example, by counting occurrences of some other timed reoccurring event) and the connection may be reassigned back to the SCS by some alternative entity besides the inactivity timer such as, for example, the CCS. 
     In the method  260 , both the CCS and the SCS may close the TCP CIR connection upon occurrence of a disconnect event such as, for example, when the need arises to free the resources as requested by the server or upon detecting that the client has closed the connection. As shown in  FIG. 8 , a disconnect event brings about transition to the end step  274 . 
     It will be understood that in at least some examples both the CCS and the SCS are capable of handling a plurality of TCP connections such as may occur when, for instance, one server  14  services many clients  18  within the mobile communications system  10 . 
     GLOSSARY OF ACRONYMS USED 
     CSP—Client-Server Protocol 
     CDMA—Code Division Multiple Access 
     CIR—Communication Initiation Request 
     CCS—Conventional Connection Server 
     GSM—Global System for Mobile Communications 
     HTTP—Hypertext Transfer Protocol 
     IMPS—Instant Message and Presence Service 
     IP—Internet Protocol 
     MO—Mobile-Originated 
     MSISDN—Mobile Station International Subscriber Directory Number 
     MT—Mobile-Terminated 
     OMA—Open Mobile Alliance 
     PAP—Push Access Protocol 
     PPG—Push Proxy Gateway 
     RF—Radio Frequency 
     SAP—Service Access Point 
     SMS—Short Message Service 
     SCS—Slow Connection Server 
     TCP—Transmission Control Protocol 
     TCP/IP—Transmission Control Protocol/Internet Protocol 
     UDP—User Datagram Protocol 
     UDP/IP—User Datagram Protocol/Internet Protocol 
     WAP—Wireless Application Protocol 
     WV—Wireless Village 
     Certain adaptations and modifications of the described embodiments can be made. Therefore, the above-discussed embodiments are considered to be illustrative and not restrictive.