Abstract:
Methods, devices, and systems are provided for allowing a single machine, such as a server, to co-host multi-SIP Archive (SAR) applications offering SIP servlet based products. The concept of a Root Application Router is introduced that is adapted to coordinate other Sub-Application Routers rather than individual SARs. These other Sub-Application Routers are fully fledged Application Routers in their own right, but are unaware of the controlling Root Application Router.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to communications and more specifically to SIP applications. 
       BACKGROUND 
       [0002]    Session Initiation Protocol (SIP) is an open signaling protocol for establishing many kinds of real-time communication sessions. Examples of the types of communication sessions that may be established using SIP include voice, video, and/or instant messaging. These communication sessions may be carried out on any type of communication device such as a personal computer, laptop computer, Personal Digital Assistant (PDA), or the like. One key feature of SIP is its ability to use an end-user&#39;s Address of Record (AOR) as a single unifying public address for all communications. Thus, in a world of SIP-enhanced communications, a user&#39;s AOR becomes their single address that links the user to all of the communication devices associated with the user. Using this AOR, a caller can reach any one of the user&#39;s communication devices, also referred to as User Agents (UAs) without having to know each of the unique device addresses or phone numbers. 
         [0003]    The concept of an Application Router has been introduced with the Java Specification Request (JSR) 289 specification, the entire contents of which are hereby incorporated herein by reference. An Application Router is responsible for application composition. Within this context, application composition is the process of “chaining” multiple applications together into a logical sequence. When multiple applications are chained together, an application will process a given SIP message and once it is done with the needed processing, the application passes the SIP message to the next application in the chain. 
         [0004]    Examples of SIP applications which may be included in an application composition include a presence application, a contact resolution application, a call setup application, a blacklist application, a voicemail application, and any other application which provides some sort of feature within the SIP architecture. As one example of an application composition, an incoming SIP message may first be filtered by a blacklist application before being passed to a normal call setup application, and then may be passed to a voicemail application after N rings. 
         [0005]    JSR 289 states that it is the role of the developer to define the application composition by providing an Application Router implementation. An application in this sense refers to a single SIP Archive (SAR) or SAR file, where the SAR file contains one or more servlets. However, in reality, an application often comprises several SAR files and several servlets (this is then known as a multi-SAR application). Each SAR file represents a wrapper of some feature of the application. The developers often include a specialized Application Router implementation that is only capable of coordinating its own SAR files. Servlets may also be contained in a Web Archive (WAR) or WAR file. 
         [0006]    JSR 289 does not define how a SIP Servlet Container should manage multiple Application Routers and, therefore, there is currently no mechanism for reliably deploying more than one multi-SAR application on the same SIP Servlet Container. This means that the application server is only able to deploy extremely limited applications, which is inefficient and counter to the main reason for using a SIP application server. As can be appreciated by one skilled in the art, this is highly inconvenient and a waste of resources since the server often has enough processing and/or memory resources to support more than one multi-SAR Application. In fact, it is analogous to using a web server such as WAS or Weblogic to only serve one set of pages or applications, instead of being able to host many websites and services simultaneously. 
         [0007]    Consider, for example, two complex applications, each consisting of multiple SARs, which are deployed to a SIP Application Server. A first application might be a PBX type application, and a second application might be a call routing application. Due to the complexities of the call routing application it is necessary to write a custom application router for each application. These logical applications and associated application routers were developed separately but now there is a desire to host them on the same Application Server. The prior art solution to this problem is constrained to only being able to deploy a single custom application router. It will, therefore, be necessary to rewrite/merge the two application routers into a single application router. Such a process is time consuming and difficult. 
         [0008]    Such an architecture is depicted in  FIG. 1 , where a communication system  100  includes a number of communication devices  108  connected to an application server  112  via a communication network  104 . As can be seen in  FIG. 1 , the application server  112  may comprise a network interface  116  that allows the application server  112  to receive incoming SIP messages from the communication network  104 . 
         [0009]    Messages received at the network interface  116  are passed to a SIP Servlet Container  120 . The SIP Servlet Container  120  is responsible for handling initial message requests and passing such requests to the application router  124 . The SIP Servlet Container  120  may also act as a Back-to-Back User Agent (B2BUA) or proxy. Once the message is passed to the application router  124 , the application router  124  examines the SIP request and selects which application (i.e., SAR file  128   a -N) needs to be executed to complete request processing. It should be noted that the application router generally does not modify any requests. Accordingly, the application router  124  identifies the appropriate SAR file  128 , and informs the SIP Servlet Container  120  of its decision. The SIP Servlet Container  120  then invokes the appropriate servlet within the SAR (determined by mechanism described in JSR 289) and the request is processed in accordance with that servlet. Once a request has been adequately processed, the SIP Servlet Container  120  transfers the request back to the network interface  116  where it can be transferred to another device in the communication network  100  for further processing. This may include passing the request to another application server or passing the request to a user communication device  108 . 
         [0010]    There are two common approaches to co-host multiple applications in accordance with JSR 289. The first is to simply run multiple instances of the application server  112 , where each server will host a single multi-SAR application. This may include virtualization technology to partition a single physical machine. The second approach is for the deployer to implement a custom application router to coordinate these applications on the same server. 
         [0011]    While present commercial practice normally deploys multiple server instances to host individual multi-SAR applications as described above, the one application per server approach can impose additional hardware and administration costs. The second approach requires the deployer to understand and re-implement routing logic for each application that is to be hosted. This process is prone to errors and increases the development/deployment time. In addition, the complexity of the machine increases with the number of applications residing thereon. 
       SUMMARY 
       [0012]    It is, therefore, one aspect of the present invention to introduce the concept of a root application router that will coordinate other sub-application routers rather than individual SARs. These other sub-application routers are fully fledged application routers in their own right but are unaware of the controlling root application router. 
         [0013]    As used herein, a SAR is an application for performing a particular function or feature of an application, but an application usually comprises several SARs (e.g., a multi-SAR application). A SAR file, WAR file, EAR, or the like is responsible for containing a servlet which is used in connection with executing an operation on a SIP message or SIP request. The SAR/WAR file is the archive that contains the actual business/application logic and routing logic for executing a particular function. 
         [0014]    A sub-application router implements the application router interface defined in JSR 289 and can be deployed within a JSR 289 compliant container on its own. However, in accordance with at least some embodiments of the present invention, these sub-application routers can be loaded and managed by the root application router and not the SIP Servlet Container. 
         [0015]    The SIP Servlet Container may be provisioned to only be aware of the root application router. Incoming SIP messages received at the SIP Servlet Container would be passed to the root application router. The root application router would then delegate incoming SIP messages (according to a selection algorithm) to an instance of a sub-application router which will take responsibility for coordinating the subsequent processing of the SIP message, thereby making this solution appear as a single application router in accordance with JSR 289. 
         [0016]    In accordance with at least some embodiments of the present invention, the routing rules defined on an application router basis (i.e., the rules used by the root application router to route messages to sub-application routers) are unimportant to the sub-application routers. Rather, this configuration will be the responsibility of the system deployer. An example is shown below: 
         [0000]    
       
         
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 &lt;pattern&gt; 
               
               
                   
                  &lt;or&gt; 
               
               
                   
                  &lt;equal&gt; 
               
               
                   
                   &lt;var&gt;request.route.uri.user&lt;/var&gt; 
               
               
                   
                   &lt;value&gt;voicemail&lt;/value&gt; 
               
               
                   
                  &lt;/equal&gt; 
               
               
                   
                  &lt;equal&gt; 
               
               
                   
                   &lt;var&gt;request.uri.user&lt;/var&gt; 
               
               
                   
                   &lt;value&gt;voicemail&lt;/value&gt; 
               
               
                   
                  &lt;/equal&gt; 
               
               
                   
                  &lt;/or&gt; 
               
               
                   
                 &lt;/pattern&gt; 
               
               
                   
                   
               
             
          
         
       
     
         [0017]    This may be interpreted as: Send messages to this sub-application router if the route URI OR the request URI user portion matches the text “voicemail”. Essentially this allows discriminating selection of sub-application routers based on message content. On receipt of a SIP message, the root application router will evaluate the rule sets in sequence. The order of evaluation is important and the deployer (usually the customer network administrator) has full control over this list. For example, a wildcard rule placed at the front means that applications behind it will never see any SIP messages. If a sub-application router does not specify any matching rules then it is assumed that it is a wild card and wants to process all messages. 
         [0018]    In accordance with at least some embodiments of the present invention, a method is provided that generally comprises: 
         [0019]    receiving a first message at a network interface of a first application server; 
         [0020]    passing the first message to a root application router within the first application server; 
         [0021]    determining, by the root application router, a sub-application router to receive and subsequently analyze the first message; and 
         [0022]    passing the first message to the sub-application router, wherein the sub-application router also resides within the first application server. 
         [0023]    SIP servlets, in accordance with at least some embodiments of the present invention, are packaged into a self-contained jar file, such as a SAR file, WAR file, EAR file, or the like, that can be deployed and undeployed individually. A SIP servlet is very similar to other types of servlets in that they enhance the interface in which they are loaded to support SIP functions. An example of another type of servlet is an http servlet which is a Java application that runs in a web server or application server and provides server-side processing, typically to access a database or perform e-commerce processing. It is a Java-based replacement for CGI scripts, Active Server Pages (ASPs) and proprietary plug-ins written in C and C++. Servlets are similar to the CGI concept but, instead of using a separate process, messages are passed to a class that runs within a virtual machine inside the server. 
         [0024]    Many servlets are written in a particular programming language (e.g., Java) which allows them to be portable between servers and operating systems. While Java is one example of a programming language that can be used to create a servlet, one skilled in the art will appreciate that embodiments of the present invention are not so limited. More specifically, embodiments of the present invention contemplate the creation of a servlet in any type of programming language which allows the SIP servlet to be portable between servers and/or operating systems. Embodiments of the present invention also contemplate a SIP servlet that is capable of running inside a virtual machine on a server (e.g., an enterprise server and particularly a SIP server). 
         [0025]    The term “computer-readable medium” as used herein refers to any tangible storage and/or transmission medium that participates in providing instructions to a processor for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, NVRAM, or magnetic or optical disks. Volatile media includes dynamic memory, such as main memory. Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, magneto-optical medium, a CD-ROM, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, RAM, PROM, EPROM, FLASH-EPROM, solid state medium like a memory card, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read. A digital file attachment to e-mail or other self-contained information archive or set of archives is considered a distribution medium equivalent to a tangible storage medium. When the computer-readable media is configured as a database, it is to be understood that the database may be any type of database, such as relational, hierarchical, object-oriented, and/or the like. Accordingly, the invention is considered to include a tangible storage medium or distribution medium and prior art-recognized equivalents and successor media, in which the software implementations of the present invention are stored. 
         [0026]    The terms “determine,” “calculate” and “compute,” and variations thereof, as used herein, are used interchangeably and include any type of methodology, process, mathematical operation or technique. 
         [0027]    The term “module”, “agent”, or “tool” as used herein refers to any known or later developed hardware, software, firmware, artificial intelligence, fuzzy logic, or combination of hardware and software that is capable of performing the functionality associated with that element. Also, while the invention is described in terms of exemplary embodiments, it should be appreciated that individual aspects of the invention can be separately claimed. 
         [0028]    The preceding is a simplified summary of embodiments of the invention to provide an understanding of some aspects of the invention. This summary is neither an extensive nor exhaustive overview of the invention and its various embodiments. It is intended neither to identify key or critical elements of the invention nor to delineate the scope of the invention but to present selected concepts of the invention in a simplified form as an introduction to the more detailed description presented below. As will be appreciated, other embodiments of the invention are possible utilizing, alone or in combination, one or more of the features set forth above or described in detail below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a block diagram depicting a communication system in accordance with embodiments of the prior art; 
           [0030]      FIG. 2  is a block diagram depicting a communication system in accordance with at least some embodiments of the present invention; and 
           [0031]      FIG. 3  is a flow diagram depicting a method of processing a SIP message in accordance with at least some embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    The invention will be illustrated below in conjunction with an exemplary communication system. Although well suited for use with, e.g., a system using a server(s) and/or database(s), the invention is not limited to use with any particular type of communication system or configuration of system elements. Those skilled in the art will recognize that the disclosed techniques may be used in any communication application in which it is desirable to allow a server to host multiple servlets. 
         [0033]    The exemplary systems and methods of this invention will also be described in relation to analysis software, modules, and associated analysis hardware. However, to avoid unnecessarily obscuring the present invention, the following description omits well-known structures, components and devices that may be shown in block diagram form, are well known, or are otherwise summarized. 
         [0034]    For purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the present invention. It should be appreciated, however, that the present invention may be practiced in a variety of ways beyond the specific details set forth herein. 
         [0035]    With reference now to  FIG. 2 , an exemplary communication system  200  will be described in accordance with at least some embodiments of the present invention. More specifically, the communication system  200  includes a communication network  104  adapted to interconnect one or more communication devices  108  with an application server  204 . 
         [0036]    The communication network  104  may be any type of known communication medium or collection of communication mediums and may use any type of protocols to transport messages between endpoints. The communication network  104  may include wired and/or wireless communication technologies. The Internet is an example of the communication network  104  that constitutes and IP network consisting of many computers and other communication devices located all over the world, which are connected through many telephone systems and other means. Other examples of the communication network  104  include, without limitation, a standard Plain Old Telephone System (POTS), an Integrated Services Digital Network (ISDN), the Public Switched Telephone Network (PSTN), a Local Area Network (LAN), a Wide Area Network (WAN), a Session Initiation Protocol (SIP) network, any type of enterprise network, and any other type of packet-switched or circuit-switched network known in the art. In addition, it can be appreciated that the communication network  104  need not be limited to any one network type, and instead may be comprised of a number of different networks and/or network types. 
         [0037]    The communication devices  108  may be any type of known communication or processing device such as a personal computer, laptop, Personal Digital Assistant (PDA), cellular phone, smart phone, telephone, analog phone, DCP phone, or combinations thereof. A single communication device  108  may be controlled by or be associated with a single user or may be adapted for use by many users (e.g., an enterprise communication device that allows any enterprise user to utilize the communication device upon presentation of a valid user name and password). 
         [0038]    Each of the communication devices  108  may be associated with the same user. In other words, the communication devices  108  may belong to a single user and may correspond to different types of communication devices. As one example, the user may have four communication devices  108  each of which correspond to a personal phone, a work phone, a personal computer, and an email retrieval device, respectively, of a single user. Alternatively, each of the communication devices  108  may be owned and operated by (e.g., associated with) a different user. 
         [0039]    In general, the communication device  108  may be adapted to support video, audio, text, and/or data communications with other communication devices  108 . The type of medium used by the communication device  108  to communicate with other communication devices  108  may depend upon the communication applications available on the communication device  108 . 
         [0040]    In accordance with at least some embodiments of the present invention, one or more communication devices  108  may send a message, such as a SIP message, to the application server  204  where it is received at the server&#39;s network interface  208 . The network interface  208  may include a communication port and/or network adaptor. As one example, the network interface  208  may comprise an Ethernet port and an Ethernet card/adaptor. As another example, the network interface  208  may comprise an antenna and an 802.11 or Bluetooth adaptor. Thus, as can be appreciated by those skilled in the art, the network interface  208  may support wired and/or wireless connections between the application server  204  and the communication network  104  and may further support multiple communication protocols. 
         [0041]    The application server  204  may further comprise a SIP Servlet Container  212  for handling messages initially received at the application server  204 . Additionally, the SIP Servlet Container  212  may be responsible for transferring SIP requests to one or more applications  224  stored on the application server  204  where the requests can be processed in accordance with the functionality of the application  224 . 
         [0042]    With reference now to  FIGS. 2 and 3 , messages received at the SIP Servlet Container  212  from the network interface  208  (step  304 ) may be passed to a root application router  216  (step  308 ). The root application router  216  may be responsible for coordinating the disbursement of SIP messages among the multiple sub-application routers  220  of the application server  204 . More specifically, the root application router  216  may comprise the business rules or logic which define how a particular message or request should be routed among the sub-application routers  220  and may apply such rules (step  312 ) in identifying a target sub-application router  220  (step  316 ). Even more specifically, the root application router  216  may act as the hierarchical master or message gatekeeper for the sub-application routers  220 . Thus, any message that is received at a sub-application router  220  is received via the root application router  216 . 
         [0043]    In accordance with at least some embodiments of the present invention, however, the sub-application routers  220  are unaware of the root application router  216  and any algorithms executed by the root application router  216 . Instead, from the sub-application router&#39;s  220  perspective, the messages are received from the SIP Servlet Container  212 , processed by the sub-application router  220 , and sent back to the SIP Servlet Container  212 , which is adapted to invoke the root application router  216  again to determine if there is another SAR  228  in the multi-SAR application  224  that should see the request. It should also be noted that a request can match rules for two or more sub-application routers  220   a  and  220   b . In this circumstance, when the root application router  216  has determined that a request is to be routed to the sub-application routers  220   a  and  220   b , the root application router  216  can pass the request to the first sub-application router  220   a  and once the corresponding first application  224   a  is done processing the message, the root application router  216  automatically passes the request on to the next sub-application router  220   b.    
         [0044]    When a sub-application router  220  receives a message (step  320 ) the sub-application router  220  analyzes the message to determine which application  224  will be responsible for actually processing the message (step  324 ). Accordingly, the sub-application router  220  does not actually process the message itself, but just analyzes information in the message to determine which application  224  will be used to process the message. 
         [0045]    Upon making such a determination, the sub-application router  220  sends the message back to the SIP Servlet Container with an identification of the application  224  to process the message. The SIP Servlet Container  212  receives the message, analyzes the application identification, and forwards the message to the appropriate application  224 . As can be seen in  FIG. 2 , the applications  224  may comprise two or more SAR files  228 , each containing a servlet, such as a SIP servlet. 
         [0046]    When a message is assigned to a particular application  224 , the SIP Servlet Container  212  invokes the appropriate servlet within a SAR file  228  of the application  224  to actually process the message (step  328 ). As can be appreciated by those skilled in the art, although the applications  224  are depicted as comprising three and two SAR files  228   a ,  228   b , respectively, an application  224  may comprise a greater or lesser number of SAR files  228  depending upon the function of the application  224 . For example, an application  224  may comprise one, two, three, four, or more SAR files  228  without departing from the scope of the present invention. An application  224  comprising two or more SAR files  228  is referred to herein as a multi-SAR application  224 . Embodiments of the present invention provide the ability to co-host a plurality of multi-SAR applications  224  on a common server  204 , particularly through the use of a root application router  216 . 
         [0047]    In accordance with at least some embodiments of the present invention, an application  224  provides a general functionality or feature for a SIP message. The SAR file(s)  228  contained within an application  224  contain the servlets which are the processes that execute the steps needed to provide the function of the application  224 . As one example, an application  224  may correspond to a voicemail function. The SAR files  228  within the voicemail application  224  may contain servlets which execute processes such as determining that a call should go to voicemail coverage, identifying a location of an appropriate voicemail server, transferring the call to the voicemail server, providing IVR functions to the caller, recording a message from the caller, and storing the message in the voicemail server. Of course, some of the voicemail processes described above may be executed as separate SAR files on other applications  224 . Furthermore, voicemail is but one example of an exemplary function provided by an application  224 . Other types of functions provided by an application  224  include, but are not limited to, a call forwarding function, a call routing function, a coverage function, a recording function, a call setup function, a blacklist function, a whitelist function, an incoming call notification function, an end call function, and a bill customer function. Other functions made available via an application  224  will become apparent to those skilled in the art and are also considered within the scope of the present invention. 
         [0048]    When a message is being processed by a servlet within a SAR file  228 , the servlet may generate a second message or SIP request (e.g., a call transfer message in the voicemail application example described above). Thus, in step  332  it is determined whether or not a new request or message has been generated by the servlet due to its processing of the initially received message. If this inquiry is answered affirmatively, then the message is transferred back to the SIP Servlet Container  212  where it can be forwarded to another computational component, which may or may not reside in the application server  204  (step  336 ). If such a message is generated by the servlet, the second SIP message is sent to a computational component without causing the second message to be evaluated by the root application router  216 . 
         [0049]    Once the application  224  has invoked all of its servlets within the SAR files  228  and the message has been processed by those servlets or if the inquiry of step  332  is answered negatively, the method continues by determining if there is additional processing required for the first message (step  340 ). If the message requires additional processing, possibly by another application  224 , then the method returns to step  304  and the message is forwarded to the SIP Servlet Container  212  which subsequently provides the message back to the root application router  216 . If no additional processing is required, then the method ends (step  344 ). Of course, as a part of completing the message processing, the message may be transferred out of the application server  204  via the network interface  208 . 
         [0050]    As can be appreciated by those skilled in the art, although the application server  204  depicted in  FIG. 2  contains two sub-application routers  220   a ,  220   b , an application server  204  may comprise a greater or lesser number of sub-application routers  220  in accordance with embodiments of the present invention. 
         [0051]    Likewise, although the application server  204  is depicted as having only two applications  224   a ,  224   b , an application server  204  may comprise a greater or lesser number of applications  224  in accordance with embodiments of the present invention. Furthermore, the number of sub-application routers  220  does not, and usually will not, match the number of applications  224  in the application server  204 . Accordingly, a single sub-application router  220  may be adapted to make a message routing decision between a plurality of applications  228 . In other words, a sub-application router  220  may be adapted to determine whether a message should be sent to a first, second, third, fourth, etc. application  224  for processing and may make different decisions for different messages received at the sub-application router  220 . Furthermore, two sub-application routers  220  may be adapted to route a message to a common application  224  (i.e., sub-application routers  220  may share an application  224 ), although such an embodiment will depend on a number of other considerations. 
         [0052]    While the above-described flowchart has been discussed in relation to a particular sequence of events, it should be appreciated that changes to this sequence can occur without materially effecting the operation of the invention. Additionally, the exact sequence of events need not occur as set forth in the exemplary embodiments. The exemplary techniques illustrated herein are not limited to the specifically illustrated embodiments but can also be utilized with the other exemplary embodiments and each described feature is individually and separately claimable. 
         [0053]    The systems, methods and protocols of this invention can be implemented on a special purpose computer in addition to or in place of the described communication equipment, a programmed microprocessor or microcontroller and peripheral integrated circuit element(s), an ASIC or other integrated circuit, a digital signal processor, a hard-wired electronic or logic circuit such as discrete element circuit, a programmable logic device such as PLD, PLA, FPGA, PAL, a communications device, such as a server, personal computer, any comparable means, or the like. In general, any device capable of implementing a state machine that is in turn capable of implementing the methodology illustrated herein can be used to implement the various communication methods, protocols and techniques according to this invention. 
         [0054]    Furthermore, the disclosed methods may be readily implemented in software using object or object-oriented software development environments that provide portable source code that can be used on a variety of computer or workstation platforms. Alternatively, the disclosed system may be implemented partially or fully in hardware using standard logic circuits or VLSI design. Whether software or hardware is used to implement the systems in accordance with this invention is dependent on the speed and/or efficiency requirements of the system, the particular function, and the particular software or hardware systems or microprocessor or microcomputer systems being utilized. The analysis systems, methods and protocols illustrated herein can be readily implemented in hardware and/or software using any known or later developed systems or structures, devices and/or software by those of ordinary skill in the applicable art from the functional description provided herein and with a general basic knowledge of the communication and computer arts. 
         [0055]    Moreover, the disclosed methods may be readily implemented in software that can be stored on a storage medium, executed on a programmed general-purpose computer with the cooperation of a controller and memory, a special purpose computer, a microprocessor, or the like. In these instances, the systems and methods of this invention can be implemented as program embedded on personal computer such as an applet, JAVA® or CGI script, as a resource residing on a server or computer workstation, as a routine embedded in a dedicated communication system or system component, or the like. The system can also be implemented by physically incorporating the system and/or method into a software and/or hardware system, such as the hardware and software systems of a communications device or system. 
         [0056]    It is therefore apparent that there has been provided, in accordance with embodiments of the present invention, systems, apparatuses and methods for co-hosting SIP servlet applications on a server. While this invention has been described in conjunction with a number of embodiments, it is evident that many alternatives, modifications and variations would be or are apparent to those of ordinary skill in the applicable arts. Accordingly, it is intended to embrace all such alternatives, modifications, equivalents and variations that are within the spirit and scope of this invention.