Abstract:
A method for delivering electronic services in a personal area network (PAN) can include providing a kiosk in a publicly traversable area. The kiosk can be configured to deliver electronic services over short-range radio communications links to wireless devices in a personal area network (PAN). The kiosk also can be configured to communicate over an existing physical communications link medium. A PAN can be established in the publicly traversable area. Electronic services can be selectably retrieved through the existing physical communications link medium into the kiosk. Finally, the retrieved selected electronic services can be delivered to wireless devices in the PAN over the short-range radio communications link. Notably, the step of establishing a PAN in the publicly traversable area can include establishing a BLUETOOTH-based PAN with wireless devices in the publicly traversable area. In addition, the step of providing a kiosk first can include retrofitting an existing kiosk both with a short-range radio frequency communications system, and with a host computing device for selectively retrieving electronic services over the existing physical communications link medium, and for delivering selected electronic services to the wireless devices in the PAN. Second, the retrofitted kiosk can be activated in the publicly traversable area.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of, and accordingly claims the benefit of, U.S. patent application Ser. No. 09/803,256, filed with the U.S. Patent and Trademark Office on Mar. 9, 2001, now U.S. Pat. No. ______. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    This invention relates to the field of personal area networking and more particularly to a system and method for providing kiosk service offerings in a personal area network. 
         [0004]    2. Description of the Related Art 
         [0005]    In recent times, the Internet has experienced phenomenal growth with more and more people accessing data and applications on the Internet through personal computers, and more recently, network computers. Historically, computing applications have been distributed as shrink-wrapped client applications. More recently, however, businesses have invested in Internet-distributed, Web-based applications, for instance Web-based customer relationship management (CRM) applications. An application service provider (ASP) is an entity that offers individuals and companies access to applications and related services over the Internet that would otherwise have to be located in their own personal or enterprise computers. Sometimes referred to as “apps-on-tap,” ASP services are an important alternative, not only for smaller companies with low budgets for information technology, but also for larger companies as a form of outsourcing. 
         [0006]    While ASPs can provide applications and services to enterprises and individuals on a pay-per-use or subscription basis, larger entities provide their own internal ASP service moving applications off personal computers and installing the applications on an application server designed to communicate with thin-client workstations. By employing an ASP architecture, enterprises can reassert central control over application cost and usage similar to the central control experience by enterprises prior to the advent of the personal computer during the era of the mainframe computer. 
         [0007]    To date, the ASP architecture has not been employed as widely in the wireless arena as it has in the wire-line arena. Specifically, whereas client access to distributable applications is growing among traditional wire-line networked clients, client access has been limited for wireless devices, such as handheld computers. Recently, pervasive computing has suggested the distribution of data to wireless devices using conventional infrared communications technology. In terms of wire-bound, cable replacement, the infrared standard promulgated by the Infrared Data Association (IRDA) is well known and widespread. Though the IRDA promulgated standard is a fast wireless technology, the IRDA promulgated standard is limited to point-to-point connections and above all, infrared communications require a clear line-of-sight between an infrared receiver and an infrared transmitter. Additionally, infrared communication technologies have experienced problems with incompatible standard implementations. 
         [0008]    Recently, wireless phone service providers also have begun to provide wireless access to Internet distributed data through cellular communications links. Still, long-range radio communication technologies like cellular communications links can be expensive and power-consuming. Moreover, cellular transmitters and receivers require device housing space which can dramatically add to the overall size of a wireless device. Finally, long-range radio communications links can be limited in bandwidth. Hence, cellular technologies are not suitable for the distribution of applications from an ASP to pervasive computing devices such as handheld computers. 
         [0009]    A new type of wireless connection has been introduced into the wireless market. Emerging standards for personal area networks (PANs), for instance the BLUETOOTH™ standard, enjoys a communications profile which is substantially different than the communications profile associated with cellular networks and infrared technologies. In particular, unlike cellular networks, PANs operate over a very limited local range. As an example, BLUETOOTH operates in “piconets” having a normal range of ten (10) meters and a maximum range of approximately one-hundred (100) meters. Accordingly, short-range radio communication links lack the deficiencies of both infrared and cellular technologies which have limited the distribution of electronic services such as applications and data over wireless communications links. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention provides a system and method for providing electronic services such as applications and data to wireless devices in a personal area network (PAN) via a kiosk. The invention incorporates service discovery protocols and short-range radio communications to allow wireless devices entering the PAN to identify the kiosk and request therefrom selected electronic services. In consequence, electronic services can be delivered to a wide variety of wireless devices without consuming substantial system resources and network bandwidth. Additionally, heretofore single-purpose existing kiosks, such as payphones, ticket counters and gasoline station islands, can be extended to offer new electronic services thereby adding value to these existing kiosks. 
         [0011]    A method for providing kiosk service offerings can include several steps. FIrst, a kiosk can be configured to provide electronic services over short-range radio communications links to wireless devices in a personal area network (PAN). In particular, in one aspect of the present invention, the configuring step can include retrofitting an existing kiosk both with a short-range radio frequency communications system, and with a host computing device for selectively retrieving electronic services over the existing physical communications link medium, and for delivering selected electronic services to the wireless devices in the PAN. The kiosk also can be configured to communicate over an existing physical communications link medium. For instance, the existing physical communications link medium can be one of a telephone network communications link and a data communications link. Second, a short-range radio communications link can be established with a wireless device in the PAN. In one aspect of the invention, the short-range radio communications link can be a BLUETOOTH-based communications link. Third, selected electronic services can be retrieved over the existing physical communications link medium. Finally, the retrieved selected electronic services can be delivered to the wireless device in the PAN over the short-range radio communications link. 
         [0012]    The step of retrieving specified electronic services over the existing communications network can include retrieving electronic messages from an electronic mail server communicatively linked to the kiosk over the existing physical communications link medium. In consequence, the step of delivering the retrieved specified electronic services to the wireless device in the PAN over the short-range radio communications link can include delivering the retrieved electronic mail to an electronic mail client in the wireless device. By comparison, the step of retrieving specified electronic services over the existing physical communications link medium can include retrieving an application from an application service provider (ASP) communicatively linked to the kiosk over the existing physical communications link medium. Accordingly, the step of delivering the retrieved specified electronic services to the wireless device in the PAN over the short-range radio communications link can include delivering the retrieved application for execution in the wireless device. 
         [0013]    Importantly, the method of the invention can additionally include the steps of determining if the specified electronic services wholly reside in the kiosk; and, if it is determined that the specified electronic services wholly reside in the kiosk, delivering the specified electronic services to the wireless device in the PAN without retrieving the specified electronic services over the existing physical communications link medium. Also, it can be determined if components of the specified electronic services reside in the kiosk. Subsequently, the components determined to reside in the kiosk can be delivered to the wireless device while components not residing in the kiosk can be retrieved from over the existing physical communications link medium. Advantageously, the step of delivering the retrieved specified electronic services to the wireless device in the PAN over the short-range radio communications link can include delivering retrieved components of the specified electronic services to the wireless device while retrieving remaining components of the specified electronic services. 
         [0014]    A kiosk for distributing electronic services to wireless devices in a PAN can include a kiosk configured to communicate with a communications network over an existing physical communications link medium; a network communications client for communicating with servers in the communications network; a short-range radio communications system for communicating with wireless devices in the PAN; and, a list of electronic services which can be distributed to wireless devices in the PAN, the electronics services in the list residing locally in the kiosk and remotely in the servers in the communications network. Notably, the short-range radio communications system can include a short-range radio communications system configured in accordance with BLUETOOTH specifications. In addition, the kiosk can be a public telephone, a gasoline station island, an airline check-in desk, a ticketing booth, a retail check-out counter, a toll booth, or an automatic teller machine. The physical communications link medium can be a telephone network communications link or a data communications link. Moreover, the server can be an application server. Finally, the communications network can be an Internet. 
         [0015]    A method for delivering electronic services in a personal area network (PAN) can include providing a kiosk in a publicly traversable area. The kiosk can be configured to deliver electronic services over short-range radio communications links to wireless devices in a personal area network (PAN). The kiosk also can be configured to communicate over an existing physical communications link medium. A PAN can be established in the publicly traversable area. Electronic services can be selectably retrieved through the existing physical communications link medium into the kiosk. Finally, the retrieved selected electronic services can be delivered to wireless devices in the PAN over the short-range radio communications link. Notably, the step of establishing a PAN in the publicly traversable area can include establishing a BLUETOOTH-based PAN with wireless devices in the publicly traversable area. In addition, the step of providing a kiosk first can include retrofitting an existing kiosk both with a short-range radio frequency communications system, and with a host computing device for selectively retrieving electronic services over the existing physical communications link medium, and for delivering selected electronic services to the wireless devices in the PAN. Second, the retrofitted kiosk can be activated in the publicly traversable area. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0016]    There are presently shown in the drawings embodiments which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
           [0017]      FIG. 1  is a schematic diagram illustrating an exemplary system for providing kiosk service offerings in a PAN. 
           [0018]      FIG. 2  is a schematic diagram illustrating a device enabled for short-range radio communications in the PAN of  FIG. 1 . 
           [0019]      FIG. 3  is an architecture suitable for use in the device of  FIG. 2 . 
           [0020]      FIG. 4  is a flow chart illustrating a process for receiving distributed electronic services in a PAN via a PAN-configured kiosk. 
           [0021]      FIG. 5  is a flow chart illustrating a process for distributing electronic services from an application service provider in a communications network to a wireless device in a PAN via a PAN-configured kiosk. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    The present invention is a system and method for providing kiosk service offerings in a personal area network (PAN). More specifically, a kiosk, for example a public telephone, a gasoline station island, an airline check-in desk, a ticketing booth, a retail check-out counter, a toll booth, or an automatic teller machine, can be configured with a short-range radio communications system for transmitting and receiving data wirelessly in a PAN. Notably, the kiosk can be communicatively linked to an existing communications network. The kiosk can establish short-range radio communications links with wireless devices which enter the PAN. Once a short-range radio communications link has been established with the wireless device, the kiosk can retrieve over the existing communications network selected electronic services such as applications and data. The kiosk, in turn, can transmit the retrieved selected electronic services to the wireless device in the PAN over the short-range radio communications link. 
         [0023]      FIG. 1  is a schematic diagram illustrating an exemplary system for providing kiosk service offerings in a PAN. As shown in  FIG. 1 , the system can include both a PAN  130  and an existing communications network  110 , for example the Internet. The existing communications network  110  can include a plurality of servers  120  which can distribute electronic services such as data and applications to requesting clients. The electronic services can be stored in network storage  125 . Notably, while  FIG. 1  depicts network storage  125  as an entity positioned closely to the servers  120 , the invention is not limited in this regard and the network storage  125  can be positioned elsewhere in the communications network from where the network storage  125  can be remotely accessed by the servers  120 . Importantly, the servers  120  can be application servers or data servers. 
         [0024]    In accordance with the inventive arrangements, a kiosk  100  can be communicatively linked to the communications network  110 . In particular, the kiosk  100  can be linked through wireline means, for example a T-1 or DSL communications link, or wirelessly through cellular or other radio frequency (RF) means. In accordance with the inventive arrangements, the kiosk  100  can be any self-contained structure, such as a public telephone, a gasoline station island, an airline check-in desk, a ticketing booth, a retail check-out counter, a toll booth, or an automatic teller machine. Advantageously, typical kiosks include access to communications networks such as a public switched telephone network (PSTN) via communications links through which the communications network  110  can be accessed. 
         [0025]    The kiosk  100  can be configured with short a range radio frequency system with which the kiosk  100  can participate in the PAN  130 . By participate, it is meant that the kiosk  100  can detect PAN-enabled devices  140  geographically proximate to the kiosk  100  with which the kiosk  100  can establish a communications connection over which the kiosk  100  can transmit and receive data. Typically, the geographic proximity between two communicating devices in the PAN  130  does not exceed 100 meters, although the invention is not limited to the precise communications characteristics of the short-range radio frequency communications system used to establish the PAN  130 . Rather, the present invention contemplates the characteristics of any suitable short-range radio frequency communications system with which the PAN  130  can be established. 
         [0026]    The kiosk  100  can be PAN-enabled by including with the kiosk  100  a host device configured for short-range radio communications in the PAN  130 .  FIG. 2  is a schematic diagram illustrating a host device  200  configured for short-range radio communications in the PAN  130  of  FIG. 1 . The host device  200  can include a central processing unit (CPU)  205 , memory  210 A,  210 B, a display interface  215 A and corresponding display  215 B, an input/output (I/O) interface  230  and input device  240 . As shown in the figure, in one aspect of the present invention memory  210 A can be volatile, random access memory (RAM). Similarly, memory  210 B can be non-volatile, read-only memory. The display controller  215 A can be any controller suitable for presenting data visually through the display  215 B. The display  215 B can be any conventional display such as an LCD, monitor, etc. The I/O interface  230  can be any suitable interface for receiving or transmitting data to and from the host device  200 . Examples of I/O interfaces can include a serial interface, universal serial bus (USB) port, infrared port, fire-wire port, etc. Finally, the input device  240  can be any suitable device for providing user input for the device  200 . Examples of input devices can include a keyboard, microphone, pointing device, touch-screen, etc. 
         [0027]    Each of the CPU  205 , memory  210 A,  210 B, display interface  215 A and corresponding display  215 B, I/O interface  230  and input device  240  can be arranged conventionally as is the case with conventional computers. In particular, each of the CPU  205 , memory  210 A,  210 B, display interface  215 A and corresponding display  215 B, I/O interface  230  and input device  240  can be communicatively linked through bus  220 . Notwithstanding, the invention is not limited either in regard to the particular conventional computing components which comprise the host device  200 , or the particular arrangement of the conventional computing components. Rather, as will be apparent to one skilled in the art, the host device  200  configuration is limited only inasmuch as the host device  200  must include a short range radio communications system  250 . 
         [0028]    The short range radio communications system  250  can include an analog short range radio  280  and a digital host controller  255 ,  270 . The host controller  255 ,  270  can include a host interface (HI)  255  and a link manager (LM)  270 . The LM  270  can include a digital signal processor referred to as a link controller (LC)  275  and a CPU core  265 . The HI  255  can also include the CPU core  265  and an external interface  260  to the bus  220  of the host device  200 . The LC  275  consists of circuitry and firmware which can perform baseband processing and physical layer protocols such as ARQ protocol and FEC coding. The function of the LC  275  includes asynchronous data transfers, synchronous data transfers, and optionally, audio coding and encryption. The CPU core  265  can be programmed to handle inquiries and filter page requests without involving the host device  200 . Specifically, the host controller  255 ,  270  can be programmed to answer certain page messages and authenticate remote links. The LM  270  executes on the CPU core  265 . The LM discovers other LMs and communicates with them via a link manager protocol (LMP) to perform its service provider role and to use the services of the underlying LC. 
         [0029]    A short range radio communications system in one aspect of the present invention can be implemented using standard Bluetooth™ wireless technology as described in Riku Mettala, Bluetooth Protocol Architecture Version 1.0, Nokia Mobile Phones, (1999) and 1 Specification of the Bluetooth System Wireless Connections Made Easy, Bluetooth SIG (1999), both incorporated herein by reference. Bluetooth is a low-cost, low-power, short-range radio link for mobile devices and for WAN/LAN access points. Bluetooth offers fast and reliable digital transmissions of both voice and data over the globally available 2.4 GHz ISM (Industrial, Scientific and Medical) band. The Bluetooth specification defines a short (around 10 m) or optionally a medium range (around 100 m) radio link capable of voice or data transmission up to a maximum capacity of 720 Kb/s per channel. Radio frequency (RF) operation is in the un-licensed industrial, scientific and medical (ISM) band at 2.4 to 2.48 GHz, using a spread spectrum, frequency hopping, full-duplex signal at up to 1600 hops/sec. The signal hops among seventy-nine (79) frequencies at 1 MHz intervals to give a high degree of interference immunity. RF output is specified as 0 dBm (1 mW) in the 10 m-range version and −30 to +20 dBm (100 mW) in the longer range version. 
         [0030]    Bluetooth enabled devices which come within range of each other can establish an ad hoc point-to-point and/or point-to-multipoint connections. Bluetooth enabled devices dynamically can be added to or removed from a PAN. Notably, two or more Bluetooth enabled units which share a channel form a piconet. Several piconets can be established and linked together in ad hoc “scatternets” to allow communication and data exchange in flexible configurations. If several other piconets are within range, each can operate independently while maintaining access to the full bandwidth of the scatternet. Each piconet is established by a different frequency hopping channel. All users participating on the same piconet are synchronized to this channel. Notably, unlike infrared devices, Bluetooth enabled devices are not limited to line-of-sight communication. 
         [0031]      FIG. 3  illustrates a short range radio communications architecture  300  suitable for use in the device of  FIG. 2 . The architecture  300  can include radio communications device based low level baseband services  322  and host device-based high level protocols  324  through which external host computing applications  320  can communicate using standard communications protocols  318  such as TCP/IP or UDP/IP with other devices in the PAN. Notably, in order to facilitate compatibility between different hardware implementations associated with the low level baseband services  322 , a host controller interface (HCI)  306  can be used as a common interface between the host computing device and the radio communications system core. Higher level protocols like the service discovery protocol (SDP)  314 , RFCOMM  316  (emulating a serial port connection) and the Telephony Control protocol (TCS)  312  are interfaced to the low level baseband services  322  via a logical link control and adaptation protocol (L2CAP)  308 . Notably, the SDP  314  allows applications to find out about available services and their characteristics when devices are moved or switched off. Among the tasks associated with L2CAP  308 , L2CAP  308  can perform the segmentation and re-assembly of data to allow larger data packets to be carried over a short range radio communications baseband connection. 
         [0032]    The host device  200  as configured in  FIG. 2  with the short range radio communications system  250  and having the architecture of  FIG. 3  can be included as both as part of a PAN-enabled kiosk such as kiosk  100  of  FIG. 1 , and as part of a PAN-enabled device such as the PAN-enabled device  140  of  FIG. 1 . Exemplary PAN-enabled devices which can be configured to operate with a short range radio communications system  250  as shown in  FIG. 2  can include personal digital assistants (PDAs), cellular phones, handheld computers, laptop/notebook computers, wristwatches, etc. In contrast, where a kiosk includes the conventional computing components shown as included in the host device  200  of  FIG. 2 , a short range radio communications system  250  can be directly connected to a computing device in the kiosk  100  wherein suitable higher level protocols for driving the short range radio communications system  250  are installed in the computing device. Alternatively, a standalone pre-configured computing device can be added to the kiosk  100  and communicatively linked to existing communications network links residing in the kiosk  100 . 
         [0033]    Referring back to  FIG. 1 , in operation a kiosk  100  can be configured with a short range radio communications system so as to participate in the PAN  130  as an electronic service provider. When a PAN-enabled device  140 , such as a Bluetooth enabled PDA enters the piconet formed by the PAN  130 , the PAN-enabled device can retrieve a list of available electronic services from the kiosk  100 . Electronic services can include, but are not limited to distributed applications and data, for example electronic mail, sports scores, and stock prices. One or more particular electronic services can be selected in the PAN-enabled device  140  responsive to which the kiosk  100  can distribute the selected electronic services to the device  140 . If, however, the kiosk  100  does not have locally stored therein a selected electronic service, the kiosk  100  can request the missing service from an server  120  in the existing communications network  110 . Upon receipt of the missing service from the appropriate server  120 , the kiosk  100  can forward the service to the PAN-enabled device  140  in the PAN  130 . 
         [0034]      FIG. 4  is a flow chart illustrating a process performed in a PAN-enabled device for receiving distributed electronic services in a PAN via a PAN-enabled kiosk. Beginning in step  402 , a PAN-enabled device entering a PAN can electronically detect the presence of the PAN using, for example conventional service discovery protocols. Service discovery protocols are well-known in the art and provide devices in ad hoc peer-to-peer networks to dynamically discover devices and services. As such, service discovery architectures enable self-configuring dynamic networks by providing a standard method for applications, services and devices to describe and to advertise their capabilities to other applications, services and devices and to discover their capabilities. Service discovery architectures also enable applications, services and devices to search other applications, services or devices for a particular capability, and to request and establish interoperable sessions with them to utilize those capabilities. 
         [0035]    Returning now to  FIG. 4 , in step  404 , the device can determine whether to connect to or ignore the PAN. Specifically, the connection determination can be performed by a user, or by the device automatically based on pre-configured selections such as “connect to all PANs” or “connect to the following PANs only”. If, in step  404  the device chooses to connect to the PAN, in step  406  the device can undertake and authentication process prior to connection during which process the device can be recognized as a legitimate PAN client and associated with a unique identifier through which other devices in the PAN can recognize and communicate with the PAN-enabled device. 
         [0036]    Once connected, in step  408 , the PAN-enabled device can identify the PAN-enabled existing kiosk and can query the kiosk for available electronic services. Alternatively, upon detecting the presence of the PAN-enabled device, the kiosk can automatically transmit a list of available electronic services to the PAN-enabled device. If in step  410  one or more electronic services are selected, either automatically by the PAN-enabled device, or manually by the user, in step  412  the selected services can be downloaded to the PAN-enabled device from the kiosk. Notably, even if no services are selected in step  410 , so long as the PAN-enabled device remains in the piconet formed by the PAN, the list of available services can be accessed. 
         [0037]    By comparison, upon detecting a PAN-enabled device, a kiosk retrofitted in accordance with the inventive arrangements can undertake the process illustrated in  FIG. 5 .  FIG. 5  is a flow chart illustrating a process for distributing electronic services from an application service provider in a communications network to a wireless device in a PAN via the retrofitted kiosk. Beginning in step  502 , the kiosk can detect the presence of a PAN-enabled device using, for example conventional service discovery protocols. In step  504 , it can be determined if the detected device is a valid subscriber to electronic services offered by the kiosk. If the detected device is not a valid subscriber, the kiosk can prompt the user of the device for pay-per-use payment in step  508 . Alternatively, the kiosk can prompt the user of the device to register for a subscription. Moreover, the kiosk can provide to the device a limited trial period subscription. In any case, the invention is not limited in regard to the precise business model for providing access to services provided by the kiosk. 
         [0038]    If in step  510  payment is received, or if in step  504  the device is determined to be a subscriber device, in step  506  it can be determined whether the detected device has associated therewith a pre-configured default electronic service. If not, in step  512  the kiosk can provide to the device a list of available services. The list can be computed based on any number of factors, for example all available services, or a limited selection based on prioritization, perceived value, or advertising revenue, historical transaction statistics, device and network resources, or a pre-configuration. In step  514 , if one or more services has been selected, or if a default service is selected, in step  516  the kiosk can determine whether the complete electronic service is available locally in the kiosk, or whether one or more components of the electronic service must be retrieved from an ASP in the existing communications network. 
         [0039]    If the kiosk is able to locally retrieve the entire selected electronic service, in step  520  the kiosk can transmit to the detected device the requested electronic service. Otherwise, if one or more components of the selected electronic service are not available locally in the kiosk, the kiosk can determine a suitable ASP from which the selected electronic service can be retrieved. Subsequently, in step  518 , the kiosk can retrieve therefrom the requested electronic service. Importantly, in the case where some of the components of the electronic service are present in the kiosk while other components of the requested electronic services must be retrieved from an ASP, the kiosk can begin transmission of the present components during the retrieval of the remaining components from the ASP. Likewise, as components are retrieved from the ASP, the retrieved components can be forwarded to the device while the remaining components are retrieved. In this way, apparent and actual response times can be reduced. 
         [0040]    Use of a kiosk configured in accordance with the inventive arrangements can permit casual use of applications by wireless devices and can involve either downloading complete applications, for example a crossword puzzle game for carry away use, or can involve more traditional ASP hosting of complex applications. Significantly, a kiosk configured in accordance with the inventive arrangements can be used for targeted service distribution, for example based on geography. More particularly, depending on the nature and location of the kiosk, particular electronic services can be stored locally in the kiosk and the kiosk can be configured to retrieve particular services from communicatively linked servers. For example, in the case of an airport or train station ticket counter, travel related electronic services such as airplane timetables, weather news, crossword puzzle programs and electronic mail can be automatically or manually distributed to travelers entering an associated PAN with a PAN enabled device. Similarly, public payphones can provide electronic services such as mapping programs and restaurant guides to devices entering an associated PAN. 
         [0041]    While the foregoing specification illustrates and describes the preferred embodiments of this invention, it is to be understood that the invention is not limited to the precise construction herein disclosed. The invention can be embodied in other specific forms without departing from the spirit or essential attributes. Accordingly, reference should be made to the following claims, rather than to the foregoing specification, as indicating the scope of the invention.