Patent Publication Number: US-10333800-B2

Title: Allocating physical nodes for processes in an execution plan

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a computer program product, system, and method for allocating physical nodes for processes in an execution plan. 
     2. Description of the Related Art 
     To run an application job involving multiple processes that execute in parallel, such as an Extract Load and Transform (“ETL”) job, a job executor reads a description of the configuration file template to determine the number of nodes on which processes will run. The job executor requests an allocation of nodes to run the job from a resource management tool, which then sends the job executor the node names that may be selected for the job. A user may then prepare a configuration file with actual node names selected from those provided by the resource management tool. The configuration file may allocate to different nodes a physical node, also known as a “fastname”, and a pool to which the node is assigned. The configuration file thus specifies actual physical resources to allocate in advance to the job before the execution plan is generated. 
     Using the configuration file, an execution plan may then be generated from the job description indicating the parts or partitions of the processes of the job to run on the selected nodes identified in the configuration file. The execution plan is then run to execute the processes on the selected node. 
     With ETL jobs, the processing may be partitioned at the nodes, where a conductor drives the entire job. Under the conductor there are section leaders, one section leader for each node, and there are multiple players for each section leader, or independent processes, that run on the same node as the section leader. Thus, the execution plan will require that players for the section leader are all assigned to the same node, which will comprise the physical node specified in the configuration file. 
     SUMMARY 
     Provided are a computer program product, system, and method for allocating physical nodes for processes in an execution plan. An execution plan is generated indicating a plurality of processes. A resource requirement is generated indicating requested physical nodes and an assignment of the processes to execute on the requested physical nodes. A determination is made from the resource requirement of a resource allocation of physical nodes for the requested physical nodes and the processes. The execution plan is updated to generate an updated execution plan indicating the physical nodes on which the processes will execute according to the received resource allocation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an embodiment of a computational environment, including a job execution environment and resource management environment. 
         FIG. 2  illustrates an embodiment of a resource requirement instance. 
         FIG. 3  illustrates an embodiment of a resource allocation instance. 
         FIG. 4  illustrates an example of an embodiment of a configuration file. 
         FIG. 5  illustrates an example of an embodiment of an allocation of section leaders and players to physical nodes. 
         FIG. 6  illustrates an embodiment of operations to generate and send a resource requirement with a request to allocate physical nodes for requested section leader nodes. 
         FIG. 7  illustrates an embodiment of operations to allocate physical nodes to processes identified in the resource requirement. 
         FIG. 8  illustrates an embodiment of operations to update an execution plan with the allocated physical nodes. 
         FIG. 9  illustrates an embodiment of computer systems in the computing environment. 
     
    
    
     DETAILED DESCRIPTION 
     With the prior art implementation, resources and nodes are selected before the execution plan is prepared, and then included in the execution plan. Thus, when the execution plan is initiated with the previously selected nodes, the selected nodes at the time the execution plan is run may not have sufficient resources to execute the processes specified in the execution plan. If a node on which the processes of the execution plan is too busy, then the process execution may be delayed, which may result in job failure or longer completion time. With the prior art implementations, reserving a node for a single application may waste node resources available on a node and running multiple applications on one node may lead to contention if the node does not have sufficient capacity and resources at the time of execution. 
     Described embodiments address the prior art problems of pre-allocating nodes in advance of preparing the execution plan. Described embodiments allow running of parallel processes of a job on a dynamically allocated set of nodes by preparing the execution plan with dummy node names or placeholders and then replacing the dummy node names with the actual node names. In this way, the physical nodes are allocated after the execution plan is generated. Further, with described embodiments, when all of the related processes cannot be accommodated on the same node machine, resources on different nodes may be requisitioned for some of the processes so the processes may run on multiple nodes to avoid failure or delays due to overloading too many processes on one node at execution time. 
       FIG. 1  illustrates an embodiment of a computational environment  100  having a job execution environment  102  and a resource management environment  104 . The job execution environment  102  includes a job executor  106  that processes a job  108 , such as an application or program, e.g., an Extract Transform and Load (“ETL”) program, to determine the processes and flow of the job  108 . The job executor  106  may process a configuration file template  110  specifying requested section leader nodes to be assigned to the processes of the job  108 . The job executor  106  may process a job description of the job  108  to generate an execution plan  112  indicating processes to execute on the requested section leader nodes designated in the configuration file template  110 . 
     In one embodiment, the execution plan  112  may specify various processes that may execute in parallel to perform different operations of the job  108 , including section leaders and players. A section leader creates and manages player processors which perform the actual job  108  execution. The section leaders also manage communication among the player processes and the conductor process. The players comprise one or more logical groups of processes used to execute the data flow logic. All players are created and may execute on a same physical node as the section leader. A conductor is a main process that starts the job  108 , determines resource requirements, assigns players to nodes, creates the section leader processes, and acts as a single coordinator for status and error messages. 
     The job executor  106  includes a resource negotiator  107  to request actual physical nodes  120  with sufficient resources on which to execute the determined processes in the execution plan  112 , e.g., section leaders and players, from a resource manager  114 , where in the execution plan  112 , the processes are designated to operate on requested section leader nodes for which there is not yet an allocated physical node  120 . In order to request physical nodes that meet the job resource requirement from the resource manager  114 , the job executor  106  may construct a resource requirement  200  having information on the processes (e.g., section leaders and players) required by the job  108 , which is processed by a resource negotiator  107  to determine how to allocate physical nodes to the processes in the execution plan  112 . Once determining an allocation, the resource negotiator  107  would request the specific physical node allocation  120  from the resource manager  114 . 
     The resource management environment  104  includes the resource manager  114  and resource availability information  116  having information on a remaining or current availability of resources in the physical nodes  120 . The resource manager  114  provides the resource negotiator  107  resource availability information  116 , which the resource negotiator  17  uses to determine the physical nodes having sufficient available resources to allocate to the processes in the execution plan  112 . The resource manager  114  would then perform the allocation as requested by the resource negotiator  107 . 
     In response to the resource requirement  200 , the resource negotiator  107  determines the allocation of physical nodes  120  to processes in the execution plan  112 , requests the resource manager  114  to implement the determined allocation, and then generates manager a resource allocation  300  having the determined allocation of physical nodes to processes to return to the job executor  106  to use to update the execution plan  112  to reflect the actual assigned physical nodes. 
     The computational environment  100  in which the job execution environment  102  and resource management environment  104  are implemented may comprise one or more servers. If multiple servers are used to implement the environment  100 , then the servers may communicate over a network, such as a Storage Area Network (SAN), Local Area Network (LAN), Intranet, the Internet, Wide Area Network (WAN), peer-to-peer network, wireless network, arbitrated loop network, etc. The environment may include storage resources comprising one or more storage devices, or an array of storage devices configured as Just a Bunch of Disks (JBOD), Direct Access Storage Device (DASD), Redundant Array of Independent Disks (RAID) array, virtualization device, tape storage, flash memory, etc. The storage devices in which the storage resources are implemented may comprise hard disk drives, solid state storage device (SSD) comprised of solid state electronics, such as a EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory, flash disk, Random Access Memory (RAM) drive, storage-class memory (SCM), etc., magnetic storage disk, optical disk, tape, etc. 
     The physical nodes  120  may each comprise a separate computing resource, such as a physical server or computer having an operating system to independently execute processes, such as a conductor, section leader, and players. In further embodiments, the physical nodes  120  may comprise a virtual machine providing a virtualization of an independent system. The physical nodes  120  may comprise a mixture of dedicated systems and virtual machines. 
       FIG. 2  illustrates an embodiment of a resource requirement instance  200   i  included in the resource requirement  200  generated by the job executor for one of the processes in the execution plan  112 . Each resource requirement instance  200   i  may include a process identifier (ID) of the process in the execution plan  112 ; a process type  204  indicating a type of the process  202 , such as conductor, section leader or player; a section leader  206  if the type  204  is a player to indicate the section leader  206  of the player; workload requirements  208  indicating an estimated consumption of computational, storage and network resources the process  202  requires to operate; a hard or soft constraint  210  indicating whether the requirement that the player  202  execute on the same physical node as the section leader  206  is a preference that can be relaxed or is a hard constraint that cannot be relaxed and must be implemented; and a requested physical node  210  that was initially assigned to execute the job  108 . The resource requirement instance  200   i  may also indicate the requested physical node  212  indicated in the execution plan  112  to execute the process  202 . 
     For the hard or soft constraint field  210 , the soft constraint for the player indicates a preference to allocate the player to the physical node on which the section leader  206  for the player is allocated, with understanding that the requirement can be relaxed if the resource manager  114  cannot locate one physical node having sufficient resources for all the players of the section leader. The hard constraint  210  for the player indicates that the resource manager  114  is required to assign the player to the physical node including the section leader for the player and fail the resource allocation and job execution if the hard constraint cannot be met. 
       FIG. 3  illustrates an instance  300   i  of the resource allocation  300  the job executor  106  or resource negotiator  107  may generate to provide information on an allocation of a physical node  120 , including a process identifier  302  for which the allocation is provided; a process type  304 , e.g., section leader and player; and an allocated physical node  306  to which the process  302  is assigned. 
       FIG. 4  is an example of a configuration file template  400 , such as configuration file template  110 , that may be created by a user to specify request nodes on which the processes, e.g., players, will execute. In the example of  FIG. 4 , the configuration file  400  provides placeholder or dummy names for the physical node name denoted as “fastname”. Thus, in  FIG. 4 , the names “$HOST_NAME1” and $HOST_NAME2″ are placeholder or dummy names of a physical node to be later determined and inserted in the place of the dummy or placeholder name. Providing a placeholder name allows the resource manager  114  to provide the actual physical node that will be used for the requested physical node after the execution plan  112  is determined, instead of having a user specify the physical node to use before the execution plan is determined. Other elements in the configuration file include a “pool” to which the node may be assigned and a resource disk identified by a path name to which data can be read or written. The configuration file template  110  may be in a format different than shown in  FIG. 4  or include additional information. 
       FIG. 5  provides example of a illustration of the allocation, including multiple physical nodes  502   1 ,  502   2 ,  502   3  for two section leaders  503   1 ,  503   2 , each having three players  504   1 ,  504   2 ,  504   3  and  505   1 ,  505   2 ,  505   3 . In the example allocation of  FIG. 5 , for section leader  503   1  one of its players  504   3  is allocated to a different physical node  502   2  than the physical node  502   1  including the section leader  503   1 . For the section leader  503   2 , the resource manager  114  was able to allocate all its players  505   1 ,  505   2 ,  505   3  to a single physical node  502   3 . 
     With described embodiments, although the preference through the soft constraint is that all players be allocated the same physical node as their section leader, the resource manager  114  may allocate players having the soft constraint to a different physical node than the section leader if there are not sufficient physical node resources available to assign all players to the same physical node as their section leader. Thus, with described embodiments, players having the soft constraint setting may be assigned to one or more physical nodes that are not allocated to the section leader. Players having the hard constraint setting may not be allocated to a physical node not including the section leader. 
       FIG. 6  illustrates an embodiment of operations performed by the job executor  106  to generate the execution plan  112  and the resource requirement  200  for use in requesting the resource manager  114  to allocate resources. Upon receiving (at block  600 ) a job description for the job  108 , such as an ETL job having multiple parallel processes, the job executor  106  receives (at block  601 ) a configuration file template  110  providing placeholder names for requested physical nodes, e.g., section leader nodes, on which job processes will run. The configuration file template  110  may be received from a user. The job executor  106  may generate a configuration object used to access the information supplied by the user in the configuration file template  110 . The number of section leader nodes on which the processes will run may be supplied by a user or determined by processing a job description of the job  108 . The job executor  106  generates (at block  602 ) an execution plan  112  indicating a plurality of players to perform the tasks of the job with parallelism, by determining conductors, section leaders and players for the job  108 , and assignment of section leaders and players to the placeholder names for the requested section leader nodes. The job executor  106  generates (at block  603 ) a resource requirement  200  indicating requested section leader nodes and an assignment of the players to execute on the requested section leader nodes, and for each of the players a soft constraint or a hard constraint  210  with respect to the player executing on the same physical node as a section leader. The soft or hard constraint may be determined by processing the requirements of the players. The job executor  106  generates for each process, e.g., section leader and player, a resource requirement instance  200   i  providing the information for the players in the fields  202 ,  204 ,  206 ,  208 ,  210 ,  212 . The information such as the workload requirements  208 , section leader  206 , and hard/soft constraint  210  may be determined by processing the execution plan  112  and job description of the job  108 . After creating the resource requirement  200 , the job executor  106  sends (at block  604 ) the resource negotiator  107  the resource requirement with request to allocate resources on physical nodes  120  for the requested section leader nodes. 
       FIG. 7  illustrates an embodiment of operations performed by the resource negotiator  107  determine an allocation of physical nodes  120  to the processes in the received resource requirement  200 . Upon receiving (at block  700 ) the resource requirement  200  with the request for allocation of physical nodes  120 , the resource negotiator  107  performs a loop of operations at block  701  through  710  for each requested physical node to which a section leader and players are assigned. Alternatively, the resource negotiator  107  may perform the loop for each section leader. For a first requested physical node, the resource negotiator  107  processes the resource availability information  116  to determine (at block  702 ) whether there is one physical node  120  having sufficient available resources to handle the execution of the section leader and players assigned to the requested physical node, or to process one section leader and all its players. If so, then the resource negotiator  107  requests (at block  703 ) the resource manager  114  to allocate one physical node  120  having sufficient resources to the section leader and players assigned to the requested physical node. From block  703 , control proceeds to block  710  to consider any further requested physical nodes, or section leaders. Otherwise, if (at block  702 ) there was no single one node  120  having sufficient resources for the section leader and players assigned to the considered requested physical node, then the resource manager  107  determines (at block  704 ) whether there is one physical node  120  having sufficient resources for the section leader and players having the hard constraint  210  assigned to the requested physical node (section leader). If (at block  705 ) there is no available physical node  120  that has sufficient resources for the section leader and all players having the hard constraint  210  indicated in the resource allocation instance  200   i  for the players, then the resource negotiator  107  fails (at block  705 ) the allocation request, and returns failure to the job extractor  106  that initiated the resource allocation request. 
     If (at block  704 ) there is an available physical node  120  that has sufficient resources for the section leader and all players having the hard constraint  210  indicated in the resource allocation instance  200   i  for the player, then the resource negotiator  107  requests (at block  706 ) the resource manager  114  to allocate the one physical node  120  having sufficient resources to the section leader and players having the hard constraint  210  assigned to the requested physical node. After requesting the allocation of the physical node  120 , if (at block  707 ) the allocated physical node  120  has sufficient additional resources for any additional players having the soft constraint  210 , then the resource negotiator  107  requests (at block  708 ) the resource manager  114  to allocate the physical node  120  to the additional players having the soft constraint for which the physical node has sufficient additional resources to accommodate. In one embodiment, the resource negotiator  107  may try to maximize the number of additional players having the soft constraint that are allocated to the available resources of the physical node. If after allocating the physical node  120  to the players having the hard constraint there are no players having a soft constraint, then control would proceed to block  710  to consider the next requested physical node or section leader. 
     If the requested allocated physical node  120  does not have sufficient resources for additional players (from the no branch of block  707 ) or after requesting allocation of additional players to the physical node (from block  708 ), the resource negotiator  107  allocates (at block  709 ) the players having the soft constraint that are not allocated to the determined physical node to at least one other physical node, so that players are split across multiple physical nodes  120  if they have the soft constraint. 
     After all processes, e.g., section leaders and players, have been allocated to the one or more physical nodes  120 , the resource negotiator  107  returns (at block  711 ) a resource allocation plan  300  to the job executor  106  indicating the allocation of the physical nodes  120  to the processes included in the resource requirement  200 , e.g., the allocation of physical nodes  120  to section leaders and players. The job executor  106  may then use the plan  300  to direct execution of the job. 
     In one embodiment, the resource negotiator  107  may send all the requests for physical nodes at blocks  703 ,  706 ,  708 , and  709  in a single request to the resource manager  114 . In this way, the resource negotiator  107  uses the received allocation from the resource manager  114  to create the resource allocation plan. 
     Certain embodiments are described with respect to allocating physical nodes to section leaders and players. In alternative embodiments, the physical nodes may be allocated to other types of processes, where certain of the processes may have a requirement to be allocated to the same physical node as other processes, yet other processes may only have a preference or soft constraint to be grouped with other processes. 
       FIG. 8  illustrates an embodiment of operations performed by the job extractor  106  to process the resource allocation plan  300  returned from the resource negotiator  107 . Upon receiving (at block  800 ) the resource allocation plan  300 , the job executor  106  updates (at block  801 ) the execution plan  112  to generate an updated execution plan  112  indicating the physical nodes  120  allocated by the resource negotiator  107  on which the players will execute according to the received resource allocation plan  300 . The updated execution plan  112  may replace the dummy names or placeholders for the requested physical node assigned to the processes (e.g., section leaders and players) within the plan  112  with the address of the physical nodes  120  on which they will run. The job executor  106  sends (at block  802 ) the updated execution plan  112  to the resource manager  114  to execute the processes (e.g., section leaders and players) on the allocated physical nodes  120 . The job executor  106  may receive (at block  804 ) from the resource manager execution status of the processes in the updated execution plan  112 . 
     The described embodiments provide a technique for the allocation of resources that occurs after the execution plan has been generated and the processes (e.g., section leader and players) have been allocated to placeholder nodes or requested section leader nodes. A resource requirement  200  is then generated that specifies the processes, such as section leaders and players, and the requested physical nodes on which they are preferred to execute. A resource negotiator may then determine an allocation of actual nodes to the processes and returns that allocation received from the resource manager  114  to the job executor  106  to use to update the execution plan with the physical nodes the resource manager provided for the processes. To optimize node assignment, the resource negotiator may assign a greater number of physical nodes than requested so that processes initially assigned to a requested physical node are allocated to multiple nodes to execute. 
     The present invention may be a system, a method, and/or a computer program product. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present invention. 
     The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire. 
     Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may comprise copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device. 
     Computer readable program instructions for carrying out operations of the present invention may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C++ or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user&#39;s computer, partly on the user&#39;s computer, as a stand-alone software package, partly on the user&#39;s computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user&#39;s computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present invention. 
     Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions. 
     These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks. 
     The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks. 
     The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions. 
     The reference characters used herein, such as i and n, are used herein to denote a variable number of instances of an element, which may represent the same or different values, and may represent the same or different value when used with different or the same elements in different described instances. 
       FIG. 9  illustrates an embodiment of a computer system  902  which may comprise an implementation of physical nodes  120  and one or more computer systems  902  in which the job execution environment  102  and resource management environment  104  may be implemented. Computer system  902  is only one example of a suitable computing node and is not intended to suggest any limitation as to the scope of use or functionality of embodiments of the invention described herein. Regardless, computer node  902  is capable of being implemented and/or performing any of the functionality set forth hereinabove. 
     The computer node  902  is operational with numerous other general purpose or special purpose computing system environments or configurations. Examples of well-known computing systems, environments, and/or configurations that may be suitable for use with computer node  902  include, but are not limited to, personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputer systems, mainframe computer systems, and distributed cloud computing environments that include any of the above systems or devices, and the like. 
     Computer node  902  may be described in the general context of computer system executable instructions, such as program modules, being executed by a computer system. Generally, program modules may include routines, programs, objects, components, logic, data structures, and so on that perform particular tasks or implement particular abstract data types. Computer node  902  may be practiced in distributed cloud computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed cloud computing environment, program modules may be located in both local and remote computer system storage media including memory storage devices. 
     As shown in  FIG. 9 , computer node  902  is shown in the form of a general-purpose computing device. The components of computer system/server  902  may include, but are not limited to, one or more processors or processing units  904 , a system memory  906 , and a bus  908  that couples various system components including system memory  906  to processor  904 . 
     Bus  908  represents one or more of any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, and a processor or local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards Association (VESA) local bus, and Peripheral Component Interconnects (PCI) bus. 
     Computer node  902  typically includes a variety of computer system readable media. Such media may be any available media that is accessible by computer node  902 , and it includes both volatile and non-volatile media, removable and non-removable media, and may be used for storing the programs and data used by the programs. 
     System memory  906  can include computer system readable media in the form of volatile memory, such as random access memory (RAM)  910  and/or cache memory  912 . Computer node  902  may further include other removable/non-removable, volatile/non-volatile computer system storage media. By way of example only, storage system  913  can be provided for reading from and writing to a non-removable, non-volatile magnetic media (not shown and typically called a “hard drive”). Although not shown, a magnetic disk drive for reading from and writing to a removable, non-volatile magnetic disk (e.g., a “floppy disk”), and an optical disk drive for reading from or writing to a removable, non-volatile optical disk such as a CD-ROM, DVD-ROM or other optical media can be provided. In such instances, each can be connected to bus  908  by one or more data media interfaces. As will be further depicted and described below, memory  906  may include at least one program product having a set (e.g., at least one) of program modules that are configured to carry out the functions of embodiments of the invention. 
     Program/utility  914 , having a set (at least one) of program modules  916 , may be stored in memory  906  by way of example, and not limitation, as well as an operating system, one or more application programs, other program modules etc., and program data. Each of the operating system, one or more application programs, other program modules, and program data or some combination thereof, may include an implementation of a networking environment. Program modules  916  generally carry out the functions and/or methodologies of embodiments of the invention as described herein. 
     Computer node  902  may also communicate with one or more external devices  918  such as a keyboard, a pointing device, a display  920 , etc.; one or more devices that enable a user to interact with the computer node  902 ; and/or any devices (e.g., network card, modem, etc.) that enable computer system/server  902  to communicate with one or more other computing devices. Such communication can occur via Input/Output (I/O) interfaces  922 . Still yet, computer node  902  can communicate with one or more networks such as a local area network (LAN), a general wide area network (WAN), and/or a public network (e.g., the Internet) via network adapter  924 . As depicted, network adapter  924  communicates with the other components of computer system/server  902  via bus  908 . It should be understood that although not shown, other hardware and/or software components could be used in conjunction with computer system/server  902 . Examples, include, but are not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data archival storage systems, etc. 
     The terms “an embodiment”, “embodiment”, “embodiments”, “the embodiment”, “the embodiments”, “one or more embodiments”, “some embodiments”, and “one embodiment” mean “one or more (but not all) embodiments of the present invention(s)” unless expressly specified otherwise. 
     The terms “including”, “comprising”, “having” and variations thereof mean “including but not limited to”, unless expressly specified otherwise. 
     The enumerated listing of items does not imply that any or all of the items are mutually exclusive, unless expressly specified otherwise. 
     The terms “a”, “an” and “the” mean “one or more”, unless expressly specified otherwise. 
     Devices that are in communication with each other need not be in continuous communication with each other, unless expressly specified otherwise. In addition, devices that are in communication with each other may communicate directly or indirectly through one or more intermediaries. 
     A description of an embodiment with several components in communication with each other does not imply that all such components are required. On the contrary a variety of optional components are described to illustrate the wide variety of possible embodiments of the present invention. 
     Further, although process steps, method steps, algorithms or the like may be described in a sequential order, such processes, methods and algorithms may be configured to work in alternate orders. In other words, any sequence or order of steps that may be described does not necessarily indicate a requirement that the steps be performed in that order. The steps of processes described herein may be performed in any order practical. Further, some steps may be performed simultaneously. 
     When a single device or article is described herein, it will be readily apparent that more than one device/article (whether or not they cooperate) may be used in place of a single device/article. Similarly, where more than one device or article is described herein (whether or not they cooperate), it will be readily apparent that a single device/article may be used in place of the more than one device or article or a different number of devices/articles may be used instead of the shown number of devices or programs. The functionality and/or the features of a device may be alternatively embodied by one or more other devices which are not explicitly described as having such functionality/features. Thus, other embodiments of the present invention need not include the device itself. 
     The foregoing description of various embodiments of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto. The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims herein after appended.