Patent Publication Number: US-10326832-B2

Title: Combining application and data tiers on different platforms to create workload distribution recommendations

Description:
BACKGROUND OF THE INVENTION 
     Technical Field 
     This disclosure relates generally to data processing systems and, in particular to managing requests received from clients. Still more particularly, the disclosure relates to load balancing and managing requests from clients. 
     Background of the Related Art 
     Workload load balancing is a technique to distribute TCP/IP-based workload requests (connections) across similar server applications to achieve optimal resource utilization, maximize throughput, minimize response time, and to avoid overloading server applications or systems. By using multiple server applications (instead of a single server application) with load balancing, one can increase reliability through redundancy. The load balancing service usually is provided by a dedicated software program or hardware device. A workload manager provides distribution recommendations to the load balancing service (i.e. a load balancer appliance). 
     In workload management environments of this type, server applications that access the same data sources typically are included in the same workload. This allows monitoring agents to verify that all of these applications are available and able to handle additional connections on behalf of the workload. It also enables a workload manager to have a consolidated view of the applications in the workload, thereby enabling easy switching of the workloads between geographically separated sites (i.e., different clusters of systems). In particular, the workload manager can signal a load balancer appliance that all connections to the server applications making up the workload are to be switched at the same time to the alternate site. This ensures that access by the applications to the data sources is only done from one site at any point in time. 
     Many customers with mainframe applications either have combined the application and data tier on the same platform (i.e., the same operating system), while others have migrated their application tier to lower cost platforms while preserving their investment in the data tier (by leaving it on its existing platform). For example, most customers continue to maintain their business critical data on the mainframe (e.g., IBM® z/OS) systems, relying on their strength of high availability and security of their data tier. But, such customers also are writing new business applications that are hosted on a different platform, for example, web-based applications within an application server running on IBM Linux on System z. This application tier accesses the data tier residing on the mainframe. As such, such customers have two different platforms to monitor to determine the availability of a workload on a site or which site is best able to handle additional workload connections. 
     BRIEF SUMMARY 
     Generally, this disclosure describes a workload request load balancing method, apparatus and computer program product that provides for the grouping under a same workload of application tiers and data tiers, even when those tiers reside on different platforms. This grouping enables a workload manager to make recommendations (to load balancer appliances) about how to distribute workload connections, e.g., based on metrics gathered from both the application and data tiers. 
     According to this disclosure, a workload manager in a site uses health, availability and capacity of the applications in the site&#39;s application tier as well as the number of application instances in the site as part of their calculations to determine how to route a workload&#39;s connections across two sites. The metrics used to make this decision are collected by application tier monitoring agents, which pass the information to the workload manager. In addition, the workload manager receives information regarding the health, availability and capacity of one or more data sharing members in the site&#39;s data tier, as well as the number of data sharing members in the site as additional information for their calculations to determine how to route a workload&#39;s connections across two sites. These metrics are collected by data tier monitoring agents, which pass the information to the workload manager. The workload manager uses these metrics, as well as learning the number of application instances and data sharing members within a site, to determine a distribution policy (or recommendation) of the workload across both sites. This recommendation is provided to one or more load balancer appliances, which then use the distribution recommendation to direct requests to the site, or to an alternate site. 
     Thus, according to this approach both applications and data sources are grouped into a workload grouping, and information about both of these tiers (application and data) is then used to determine a distribution policy for the workload. These different tiers can reside on the same or different operating system environments. 
     The foregoing has outlined some of the more pertinent features of the disclosed subject matter. These features should be construed to be merely illustrative. Many other beneficial results can be attained by applying the disclosed subject matter in a different manner or by modifying the subject matter as will be described. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the subject matter and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  depicts an exemplary block diagram of a distributed data processing environment in which exemplary aspects of the illustrative embodiments may be implemented; 
         FIG. 2  is an exemplary block diagram of a data processing system in which exemplary aspects of the illustrative embodiments may be implemented; 
         FIG. 3  illustrates a workload management environment; 
         FIG. 4  illustrates how a known multi-site workload management system is used to load balance TCP/IP workload; 
         FIG. 5  illustrates the basic method of this disclosure wherein applications and data sources are grouped and monitored as a single workload; and 
         FIG. 6  illustrates the subject matter of this disclosure, wherein both applications and data sharing members are monitored and combined into a same workload, and load balancing decisions are made that affect both tiers. 
     
    
    
     DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT 
     With reference now to the drawings and in particular with reference to  FIGS. 1-2 , exemplary diagrams of data processing environments are provided in which illustrative embodiments of the disclosure may be implemented. It should be appreciated that  FIGS. 1-2  are only exemplary and are not intended to assert or imply any limitation with regard to the environments in which aspects or embodiments of the disclosed subject matter may be implemented. Many modifications to the depicted environments may be made without departing from the spirit and scope of the present invention. 
     Client-Server Technologies 
     With reference now to the drawings,  FIG. 1  depicts a pictorial representation of an exemplary distributed data processing system in which aspects of the illustrative embodiments may be implemented. Distributed data processing system  100  may include a network of computers in which aspects of the illustrative embodiments may be implemented. The distributed data processing system  100  contains at least one network  102 , which is the medium used to provide communication links between various devices and computers connected together within distributed data processing system  100 . The network  102  may include connections, such as wire, wireless communication links, or fiber optic cables. 
     In the depicted example, server  104  and server  106  are connected to network  102  along with storage unit  108 . In addition, clients  110 ,  112 , and  114  are also connected to network  102 . These clients  110 ,  112 , and  114  may be, for example, personal computers, network computers, or the like. In the depicted example, server  104  provides data, such as boot files, operating system images, and applications to the clients  110 ,  112 , and  114 . Clients  110 ,  112 , and  114  are clients to server  104  in the depicted example. Distributed data processing system  100  may include additional servers, clients, and other devices not shown. 
     In the depicted example, distributed data processing system  100  is the Internet with network  102  representing a worldwide collection of networks and gateways that use the Transmission Control Protocol/Internet Protocol (TCP/IP) suite of protocols to communicate with one another. At the heart of the Internet is a backbone of high-speed data communication lines between major nodes or host computers, consisting of thousands of commercial, governmental, educational and other computer systems that route data and messages. Of course, the distributed data processing system  100  may also be implemented to include a number of different types of networks, such as for example, an intranet, a local area network (LAN), a wide area network (WAN), or the like. As stated above,  FIG. 1  is intended as an example, not as an architectural limitation for different embodiments of the disclosed subject matter, and therefore, the particular elements shown in  FIG. 1  should not be considered limiting with regard to the environments in which the illustrative embodiments of the present invention may be implemented. 
     With reference now to  FIG. 2 , a block diagram of an exemplary data processing system is shown in which aspects of the illustrative embodiments may be implemented. Data processing system  200  is an example of a computer, such as client  110  in  FIG. 1 , in which computer usable code or instructions implementing the processes for illustrative embodiments of the disclosure may be located. 
     With reference now to  FIG. 2 , a block diagram of a data processing system is shown in which illustrative embodiments may be implemented. Data processing system  200  is an example of a computer, such as server  104  or client  110  in  FIG. 1 , in which computer-usable program code or instructions implementing the processes may be located for the illustrative embodiments. In this illustrative example, data processing system  200  includes communications fabric  202 , which provides communications between processor unit  204 , memory  206 , persistent storage  208 , communications unit  210 , input/output (I/O) unit  212 , and display  214 . 
     Processor unit  204  serves to execute instructions for software that may be loaded into memory  206 . Processor unit  204  may be a set of one or more processors or may be a multi-processor core, depending on the particular implementation. Further, processor unit  204  may be implemented using one or more heterogeneous processor systems in which a main processor is present with secondary processors on a single chip. As another illustrative example, processor unit  204  may be a symmetric multi-processor (SMP) system containing multiple processors of the same type. 
     Memory  206  and persistent storage  208  are examples of storage devices. A storage device is any piece of hardware that is capable of storing information either on a temporary basis and/or a permanent basis. Memory  206 , in these examples, may be, for example, a random access memory or any other suitable volatile or non-volatile storage device. Persistent storage  208  may take various forms depending on the particular implementation. For example, persistent storage  208  may contain one or more components or devices. For example, persistent storage  208  may be a hard drive, a flash memory, a rewritable optical disk, a rewritable magnetic tape, or some combination of the above. The media used by persistent storage  208  also may be removable. For example, a removable hard drive may be used for persistent storage  208 . 
     Communications unit  210 , in these examples, provides for communications with other data processing systems or devices. In these examples, communications unit  210  is a network interface card. Communications unit  210  may provide communications through the use of either or both physical and wireless communications links. 
     Input/output unit  212  allows for input and output of data with other devices that may be connected to data processing system  200 . For example, input/output unit  212  may provide a connection for user input through a keyboard and mouse. Further, input/output unit  212  may send output to a printer. Display  214  provides a mechanism to display information to a user. 
     Instructions for the operating system and applications or programs are located on persistent storage  208 . These instructions may be loaded into memory  206  for execution by processor unit  204 . The processes of the different embodiments may be performed by processor unit  204  using computer implemented instructions, which may be located in a memory, such as memory  206 . These instructions are referred to as program code, computer-usable program code, or computer-readable program code that may be read and executed by a processor in processor unit  204 . The program code in the different embodiments may be embodied on different physical or tangible computer-readable media, such as memory  206  or persistent storage  208 . 
     Program code  216  is located in a functional form on computer-readable media  218  that is selectively removable and may be loaded onto or transferred to data processing system  200  for execution by processor unit  204 . Program code  216  and computer-readable media  218  form computer program product  220  in these examples. In one example, computer-readable media  218  may be in a tangible form, such as, for example, an optical or magnetic disc that is inserted or placed into a drive or other device that is part of persistent storage  208  for transfer onto a storage device, such as a hard drive that is part of persistent storage  208 . In a tangible form, computer-readable media  218  also may take the form of a persistent storage, such as a hard drive, a thumb drive, or a flash memory that is connected to data processing system  200 . The tangible form of computer-readable media  218  is also referred to as computer-recordable storage media. In some instances, computer-recordable media  218  may not be removable. 
     Alternatively, program code  216  may be transferred to data processing system  200  from computer-readable media  218  through a communications link to communications unit  210  and/or through a connection to input/output unit  212 . The communications link and/or the connection may be physical or wireless in the illustrative examples. The computer-readable media also may take the form of non-tangible media, such as communications links or wireless transmissions containing the program code. The different components illustrated for data processing system  200  are not meant to provide architectural limitations to the manner in which different embodiments may be implemented. The different illustrative embodiments may be implemented in a data processing system including components in addition to or in place of those illustrated for data processing system  200 . Other components shown in  FIG. 2  can be varied from the illustrative examples shown. As one example, a storage device in data processing system  200  is any hardware apparatus that may store data. Memory  206 , persistent storage  208 , and computer-readable media  218  are examples of storage devices in a tangible form. 
     In another example, a bus system may be used to implement communications fabric  202  and may be comprised of one or more buses, such as a system bus or an input/output bus. Of course, the bus system may be implemented using any suitable type of architecture that provides for a transfer of data between different components or devices attached to the bus system. Additionally, a communications unit may include one or more devices used to transmit and receive data, such as a modem or a network adapter. Further, a memory may be, for example, memory  206  or a cache such as found in an interface and memory controller hub that may be present in communications fabric  202 . 
     Computer program code for carrying out operations of the present invention may be written in any combination of one or more programming languages, including an object-oriented programming language such as Java™, Smalltalk, C++, C#, Objective-C, or the like, and conventional procedural programming languages. The program code 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). 
     Those of ordinary skill in the art will appreciate that the hardware in  FIGS. 1-2  may vary depending on the implementation. Other internal hardware or peripheral devices, such as flash memory, equivalent non-volatile memory, or optical disk drives and the like, may be used in addition to or in place of the hardware depicted in  FIGS. 1-2 . Also, the processes of the illustrative embodiments may be applied to a multiprocessor data processing system, other than the SMP system mentioned previously, without departing from the spirit and scope of the disclosed subject matter. 
     As will be seen, the techniques described herein may operate in conjunction within the standard client-server paradigm such as illustrated in  FIG. 1  in which client machines communicate with an Internet-accessible Web-based portal executing on a set of one or more machines. End users operate Internet-connectable devices (e.g., desktop computers, notebook computers, Internet-enabled mobile devices, or the like) that are capable of accessing and interacting with the portal. Typically, each client or server machine is a data processing system such as illustrated in  FIG. 2  comprising hardware and software, and these entities communicate with one another over a network, such as the Internet, an intranet, an extranet, a private network, or any other communications medium or link. A data processing system typically includes one or more processors, an operating system, one or more applications, and one or more utilities. The applications on the data processing system provide native support for Web services including, without limitation, support for HTTP, SOAP, XML, WSDL, UDDI, and WSFL, among others. Information regarding SOAP, WSDL, UDDI and WSFL is available from the World Wide Web Consortium (W3C), which is responsible for developing and maintaining these standards; further information regarding HTTP and XML is available from Internet Engineering Task Force (IETF). Familiarity with these standards is presumed. 
     Legacy Computer Systems 
     Mainframe computer systems are widely used for a variety of data processing functions. For example, many corporate financial and accounting systems were developed for, and operate on, mainframe computing systems. Although the use of personal computers and personal computer networks has proliferated in recent years, mainframe computer systems, referred to as legacy systems, are expected to remain popular for many types of data processing for years to come. A mainframe computer system typically includes multiple user terminals connected to a mainframe host computer. Various software applications may be resident on, or accessible to, the host computer. The user terminals, which are sometimes referred to as client terminals or “clients,” communicate with the mainframe host computer via a host communications system. The IBM 3270 terminal system is one of the more widely-used systems for communicating with host computers. Typically, a 3270 terminal does not have its own data processing capability. Instead, a 3270 terminal may display screens generated by applications running on a host, and may communicate information from a user back to a host for processing. A user interface of an IBM 3270 terminal system comprises a plurality of screens that are generated by host applications for display on the 3270 terminal. Over the past few years, many 3270 terminals have been replaced with personal computers (PCs) configured to communicate with the mainframe computer system via 3270 terminal emulation software. 
     In many applications, 3270 terminals, or other data processing devices (e.g., a PC) emulating a 3270 terminal, now access the host computer via the Internet. For example, in systems operating under the TN3270E protocols, the 3270 terminals may access application software on a host computer via a combination of a TCP/IP connection between the TN3270E client terminal and a TN3270E server, and via a Systems Network Architecture (SNA) session between the TN3270E server and the SNA application software on the host mainframe computer. 
     It is also known to integrate client-server technologies with mainframe computing environments. A representative multi-component system of this type, wherein components work together cooperatively to form a larger system, is the IBM® HyperText Transfer Protocol (HTTP) and Web Services processing environment, which may be implemented using IBM mainframe computers, such as the IBM z196 family of computing machines. This environment typically includes IBM&#39;s WebSphere® Application Server (WAS) middleware platform software product, working in conjunction with one or more transaction processing products, such as IBM Customer Information Control System (CICS®) and/or IBM Information Management System (IMS), a message processing product, such as IBM WebSphere MQ, and a relational database, such as the IBM DB2® database. An objective of a multi-component environment is to provide a high performance transaction processing computing system or environment accessible to client end-users via Internet browsers using HTTP or other Web Services. In this environment, the client end-user making the HTTP or Web Services request communicates directly with the application server. Typically, to fulfill the transaction request from the distributed client end-user, the application server invokes the services of one or more other components in the environment. One of more of these components typically execute on an operating system, such as IBM z/OS® operating system, which is often referred to as a “mainframe” operating system platform. 
     Load Balancing Workload Groups 
     As further background,  FIG. 3  illustrates a representative workload management environment  300  in which the techniques of this disclosure may be implemented. 
     In this environment, client applications  302  run on client computers  304  within or in association with the workload management environment  300 . As depicted, client applications  302  generate requests  306  for services  308 . Services  308  may include, for example, at least one of retrieving a file, retrieving a webpage, writing data, downloading a program, deleting a file, and/or other suitable types of access. Requests  306  are sent over network  310  to server applications  312  on group of computer systems  314 . Server applications  312  may be any applications configured to process requests  306  to provide services  308 . Server applications  312  may be, for example, at least one of a database server, a file transfer protocol (FTP) server, a web server, a mail server, and/or other suitable types of applications. In these illustrative examples, computer systems within group of computer systems  314  may be a computer, a computer cluster, or other configurations of computer systems configured to run server applications  312 . 
     Workload manager  316  sends requests  306  to server applications  312 . Workload manager  316  may be implemented using hardware, software, or a combination of the two. When implemented with hardware, workload manager  316  takes the form of workload manager system  318 . Workload manager system  318  comprises hardware  320  and also may include software  322 . When processor units are used in hardware  320 , these processor units may be located on the same or different computers. 
     Workload manager  316  is configured to balance workloads  324  in group of computer systems  314 . Workloads  324  are balanced by the manner in which workload manager  316  distributes requests  306  to server applications  312  running on group of computer systems  314 . Workload manager  316  may be implemented in a number of different ways. For example, workload manager  316  may include load balancing processes and may directly distribute requests  306  to server applications  312 . Alternatively, workload manager  316  may make recommendations for the distribution of requests  306 . These recommendations may then be used by a load balancer implemented as a separate component to distribute requests  306  to server applications  312 . 
     Server applications  312  may access common resources  326  when processing requests  306 . Common resources  326  may include data sources, storage systems, processor systems, routing systems, and/or other suitable types of resources. Resources may take the form of hardware, data, software, or other suitable forms. A common resource within common resources  326  is a resource that is used by two or more server applications within server applications  312 . 
     Workload manager  316  identifies which of server applications  312  receive particular requests from requests  306  based on common resources  326  used by server applications  312 . Workload manager  316  may be implemented in various devices. For example, workload manager  316  may be implemented in a switch, a domain name server, and/or other suitable types of hardware devices. In these illustrative examples, workload manager  316  selects a server application within server applications  312  to process a request in requests  306  based on group information  328  and policy  330 . Group information  328 , in these examples, is groupings of server applications  312 . For example, group information  328  comprises set of workload groups  332 . Set of workload groups  332  is comprised of server application groups  334 . Each workload group in set of workload groups  332  has two or more server application groups from server application groups  334 . In addition, weights  335  may be associated with server application groups  334 . In other words, each server application in a server application group may have one or more weights. Additionally, each server application group also may be assigned one or more weights. Weights  335  are used with policy  330 . 
     Policy  330  is one or more rules for determining which of server applications  312  receive particular requests in requests  306 . Policy  330  may include rules for assigning requests  306  based on common resources  326 . Weights  335  may be applied to policy  330  in assigning requests  306  based on common resources  326 . For example, a rule in policy  330  may be to assign all requests to server applications  312  that use a particular common resource. For example, the common resource may be a computer system in group of computer systems  314 . As another example, when accessing data sources, two data sources may be copies of each other in which different server applications in server applications  312  are assigned to each of the copies of the data source. These data sources may be synchronized or updated at some point so that the copies are identical. With this type of resource, policy  330  may include a rule that states that access to a particular cell, record, entry, table, or other portion of a data source are all made to the same copy. 
     Typically, workload manager  316  performs load balancing for a workload group. Each server application group has one or more server applications. Typically, load balancing is performed with respect to a server application group. In the illustrative examples, workload manager  316  is further configured to provide load balancing based on workload groups. For example, workload group  325  in set of workload groups  332  includes server application group  338  and server application group  340 . Some of the server applications in server application group  338  may run on the same computer system as some of the server applications in server application group  340 . This is one example of a use of common resources  326 . As another example, some of the server applications in server application group  338  may access the same data sources as some of the server applications in server application group  340 . This access to data resources is another example of common resources  326 . 
     By load balancing using server applications from server application group  338  and server application group  340  that use common resources  326 , improved performance may occur. For example, if common resources  326  include data sources  342  that are synchronized between different server applications in server application group  338  and server application group  340 , distributing the requests to server applications that use the same data source may reduce conflicts between data sources  342  when these data sources are replicated. 
     In these illustrative examples, server applications in server application group  338  and server application group  340  that use the same data source in data sources  342  are considered to be on the same computer system. As a result, server applications in the same cluster that end up in different server groups may be taken into account in load balancing when those server groups are put together into a workload group. Workload manager  316  may use the mapping of server application groups into a workload group to provide better load balancing with respect to distributing requests to server applications  312  that use common resources  326  as compared to load balancing just within a server application group. 
     Workload manager  316  also may identify performance parameters  344  generated during processing of requests  306 . Performance parameters  344  are any values that relate to the use of resources to process requests  306 . These resources may include common resources  326 . Results from analyzing performance parameters  344  may be used to identify inefficiencies in accessing common resources  326 . The result may be used to modify group information  328 . Inefficiencies may include, for example, without limitation, conflicts in data, a larger than desired number of locks for data, data access requiring more time than desired, under use of a hardware resource, and other inefficiencies. 
     The modification of group information  328  may include adding a workload group, changing server application groups within a workload group, deleting a workload group, and/or other suitable modifications. Further, changing values for weights  335  in policy  330  also may occur using the results from the analysis of performance parameters  344 . 
     The illustration of workload management environment  300  in  FIG. 3  is not meant to imply physical or architectural limitations to the manner in which different illustrative embodiments may be implemented. Other components in addition to and/or in place of the ones illustrated may be used. Some components may be unnecessary. Also, the blocks are presented to illustrate some functional components. One or more of these blocks may be combined and/or divided into different blocks when implemented in an illustrative embodiment. For example, in some illustrative examples, additional workload managers, in addition to workload manager  316 , may be present within network  310 . For example, although workload manager  316  is shown as a block separate from group of computer systems  314 , workload manager  316  may be implemented in one or more computer systems in group of computer systems  314 . 
       FIG. 4  illustrates a representative implementation of a workload management environment, such as described above with respect to  FIG. 3 . In this example, IBM® Multi-site Workload Lifeline is used to implement the management environment to load balance TCP/IP workload requests across two sites at unlimited distances, when both sites are running the same server applications and have the same data sources. Although two sites are shown, there may be additional sites. In this example, and as will be seen, the system preferably defines two (2) tiers of load balancing. Generally, a first-tier load balancer registers application groups that contain members that are in both sites. These members are considered second-tier load balancers. An external load balancer, operating as a second-tier load balancer, registers groups of server applications that are on the same site. As this external load balancer receives a workload connection request from a first-tier load balancer, the external load balancer distributes the request to one of the server applications in the matching application group. 
     Each workload that is configured to Multi-site Workload Lifeline is classified as an active/standby or active/query workload. By definition, an active/standby workload can be distributed to only one site at a time, because the workload might contain transactions that update databases. By contrast, an active/query workload can be distributed to both sites at the same time, because the workload contains only transactions that query databases. Multi-site Workload Lifeline enforces the single or dual site distribution. If more than one workload is configured, some of the workloads can be distributed to one site, some workloads can be distributed to the other site, and the remaining workloads can be distributed to both sites. 
     As seen in  FIG. 4 , and in a concrete (but non-limiting) example, each site  400  is configured as a systems complex or “sysplex.” As is well-known, a sysplex is a collection of Multiple Virtual Storage (MVS) systems that cooperate, using certain hardware and software products, to process work. The sysplex increases the number of processing units and MVS operating systems that can cooperate, which in turn increases the amount of work that can be processed at the site. It uses a standard communication mechanism (the cross-system coupling facility, or XCF) for MVS system applications that enables communication between application programs on one or multiple computers. From an architecture standpoint, typically the sysplex is made up of a number of central processor complexes (CPCs) that collaborate, through specialized hardware and software, to process a work load. A single CPC comprises a single central processor (CP) and all associated system hardware and software, controlled by a single copy of the operating system (e.g., z/OS). One typical operating scenario for a sysplex is where applications running simultaneously on separate systems must be able to access the same data, or update a single database, etc., without compromising data integrity. 
     In this implementation, which is merely representative, a first-tier load balancer  402  determines which site  400  to route a new workload request to, and forwards the request to a second-tier load balancer  404  within that site  400 . The second-tier load balancer  404  within the site determines which server application  406  within the site to route the workload request to, and forwards it to the z/OS system  408  where the server application is running. IBM Multi-site Workload Lifeline acts as a workload manager (to provide the different tiers with routing recommendations based on the availability and health of the server applications and the z/OS systems within the site. 
     In this particular implementation environment, the workload manager includes agents  410  and advisors  412   a  and  412   b . As illustrated, typically agents  410  execute on each z/OS system  408  in the two sites, and operate to monitor the health of the server applications  406  and the system where the agent is active. The agents  410  periodically send this information to the primary advisor  412   a , as indicated by the network flows labeled  2 . The primary advisor  412   a  uses this information to calculate routing recommendations for the workloads that use these server applications. The advisor  412   a  periodically sends recommendations to first-tier load balancers  402  about which site to route workload requests to, and recommendations to second-tier load balancers  404  about which server applications within a site  400  to route the workload requests to, as indicated by the network flows labeled  1 . The primary advisor  412   a  also periodically notifies the secondary advisor  412   b  about any changes in the workload states, indicated by the network flows labeled  3 , so that the secondary advisor  412   b  can take over primary advisor responsibilities if the current primary advisor  412   a  becomes non-operational. 
     Thus, when workload requests are handled by the first-tier load balancers  402 , based on routing recommendations from the advisor  412   a , the load balancer  402  selects a site  400  and forwards the request to the second-tier load balancer  404  in that site, indicated by the network flow labeled  4 . When workload requests are handled by the second-tier load balancers  404 , based on routing recommendations from the advisor  412   a , the load balancer  404  selects a server application  406  in the site and forwards it to the TCP/IP stack  414  running on the z/OS system  408 , indicated by the network flow labeled  5 . When these second-tier load balancers  404  are external, they receive routing recommendations directly from the advisor  412   a . When these second-tier load balancers  404  are internal, also known as z/OS sysplex distributors, they reside on a z/OS system  408  in the site, and receive routing recommendations directly by using z/OS Communications Server functions. 
     In another configuration (not shown), a second-tier load balancer is not responsible for routing workload requests to a server application within a site. In this case, load balancing within a site is performed by some other node, which is called an intermediary node. Typically, an intermediary node does not communicate directly with the advisor  412   a . It is used in cases where customized load balancing has been built into a workload. In this type of configuration, the z/OS sysplex distributor is still defined, but it is used only for obtaining recommendations and topology information that the first-tier load balancer uses to select the site for a workload connection request. The intermediary node makes the load balancing decision to select a server application instance within the site. 
     As explained above, typically a workload comprises one or more groups of applications that access the same data sources to provide related services for a client. In this example, preferably all server applications in a load balancer application group provide the same service for that client, and preferably each server application within an application group can provide the same services as the other applications in the group. The system provides the ability to group server applications that access different data sources into their own workload to provide more granular control of each group of applications. 
     In this example embodiment, a site is synonymous with a sysplex. Preferably, all z/OS target systems in a particular site belong to the same sysplex. In a typical configuration, and as described, the first-tier load balancer determines which site to route a new workload request to and forwards the request to a second-tier load balancer. The second-tier load balancer determines which server application within the site to route the workload request to and forwards it to the z/OS system where the server application is running. Multi-site Workload Lifeline provides the different tiers with routing recommendations based on the availability and health of the server applications and the z/OS systems within the site. 
     While the arrangement and techniques in  FIG. 4  provide significant advantages, they are limited to TCP/IP-based connection monitoring and workload switching of TCP/IP server applications only. 
     Combining Application and Data Tiers on Different Platforms to Create a Workload Group 
     With the above as background, the technique of this disclosure is now described. 
     According to this disclosure, different computing system environment tiers are monitored and combined into a same workload, and load balancing decisions are then made based on that information. In particular, in this approach both applications and data sources are grouped into a workload grouping (or “group” or, more generally, a “workload”), and information about both of these tiers is then used to determine a distribution policy for the workload. In this approach, a load balancer is controlled to route workload connections that are destined to a site or an alternate site based on the state of the application instances and data sharing members in the tiers that are grouped into the same workload. 
     In particular, and according to an embodiment of this disclosure, application instances and their data sharing members, even when supported on tiers in different operating system environments, are associated together within a same workload group so that these different types of tiers can be monitored to determine their overall suitability for handling workload connection requests directed to the sites. Monitoring agents verify the health, availability and capacity of the resources within each tier, and such information is then used by a workload manager to create a distribution policy for the workload. The workload manager provides the distribution policy to a load balancing mechanism (e.g., a load balancer appliance) that is capable of distributing workload connections to either site. The workload connections are then routed to one site, or the alternate site. 
     Thus, the workload herein is based on combining application and data tiers in the same workload and then enabling load balancing decisions to be made based on that combined workload. In the preferred embodiment, the different tiers are an application tier, and a data tier. This is not a limitation, as the notion of combining different tiers into a same workload can be practiced with other computing system and/or operating system tiers. Such other tiers include, without limitation, a web server front-end tier, an application server middleware tier, or the like. Moreover, the approach of combining application and data tiers may incorporate two or more tiers into the workload. 
       FIG. 5  illustrates the basic process at a high level. In step  500 , the application and data tiers are associated into a workload (sometimes referred to herein as a workload “group” or “grouping”). This association may be created manually (through an administrative interface, by an authorized user), automatically, programmatically, or by some combination of such activities. An application tier typically includes one or more application instances, and a data tier typically includes one or more data sharing members. Data sharing members typically comprise data stores, file systems, databases, and the like. The applications and their associated data sharing members typically share common data sources that are mirrored across at least two sites that are distinct from one another and typically remote from one another. At step  502 , monitoring agents determine the availability, health and capacity of the application and data tiers. This information is then provided to a workload manager, which uses it to create a distribution policy for the workload. This is step  504 . At step  506 , the workload manager provides the distribution policy to a load balancer. The load balancer then routes workload connections that are destined for the site (or its alternative site). This is step  508 . Thus, in the described approach, the distinct application and data tiers that comprise a same workload are monitored, and the collected information is used by a workload manager to create a distribution policy that then controls the routing of workload connections to the sites. 
     In the context of this disclosure, application instances may access the same (common) data source (or resource). Each site typically has its own copy of the data source, but these copies of the data source should not be accessed at the same time. For example, application instances that are available at each site may desire to use the same table in a database, the same rows in a table in a database, the same file, the same memory location, or any other suitable types of resources. Generalizing, a data source or resource is any accessible system, device, application, program, process, thread, data store, storage or memory location, file, object, database, database component, or the like. Such concurrent access is avoided by the techniques of this disclosure. 
       FIG. 6  illustrates a representative workload management environment in which the technique of this disclosure may be practiced. This environment is not intended to be limiting. As can be seen, and as was illustrated in  FIG. 4 , it is assumed that there are two or more sites, a pair of which is shown. In particular, a first site is designated  600   a , and a second site is designated  600   b . Typically, sites are located remote from one another. As depicted, each site  600  operates an application tier  602 , and a data tier  604 , and each such tier may be hosted in a different computing system operating system environment. A representative computing system OS environment may be an IBM z/OS Series computing system, an IBM Linux on System z Series computing system, or some other. An aspect of this disclosure is that the application tier need not be hosted on the same computing system OS platform as the data tier. For example, the data tier  604  may be hosted on a mainframe (e.g., IBM® z/OS) system, while the application tier includes application instances (e.g., web-based applications within an application server) running on IBM Linux on System z (also running on a mainframe). This example scenario, of course, is not intended to be limiting. 
     The first site  600   a  comprises several computing system platforms  608 . A platform typically comprises hardware, and an operating system. The application tier  602  in the first site  600   a  comprises a set of applications supported on several computing system platforms. In particular, a first computing system platform  608   a  supports an application instance  606 , while a second computing system platform  608   b  supports two additional application instances  606 . The data tier  604  in the first site  600   a  comprises a set of data sharing members supported on several computing system platforms. In particular, a third computing system platform  608   c  supports two data sharing members  610 , while a fourth computing platform  608   d  supports two additional data sharing members  608  as well. The computing system platforms  608   a  and  608   b  host a monitoring agent  605 , and the computing system platforms  608   c  and  608   d  host a monitoring agent  607 . First and third computing system platforms  608   a  and  608   c  may be the same or distinct. Likewise, second and fourth computing system platforms  608   b  and  608   d  may be the same or distinct. 
     The second site  600   b  also comprises several computing system platforms  608 . Here, the application tier  602  in the second site  600   b  comprises a set of applications, once again supported on several computing system platforms. In particular, a fifth computing system platform  608   e  supports two application instances  606 , while a sixth computing system platform  608   f  also supports two additional application instances  606 . The data tier  604  in the second site  600   b  also comprises a set of data sharing members supported on several computing system platforms. In particular, a seventh computing system platform  608   g  supports two data sharing members  608 , while an eighth computing platform  608   h  supports one additional data sharing member  608 . The computing system platforms  608   e  and  608   f  host the monitoring agent  605 , and the computing system platforms  608   g  and  608   h  host the monitoring agent  607 . Fifth and seventh computing system platforms  608   e  and  608   g  may be the same or distinct. Likewise, sixth and eighth computing system platforms  608   f  and  608   h  may be the same or distinct. 
     The architecture of each site shown in  FIG. 6  is merely for exemplary purposes, and it is not intended to be limiting. As noted, various elements of the computing systems may be integrated or distinct. In addition, the monitoring agents  605  and  607  may be distinct or integrated into a single module. 
     The operation of the various components is now described. In particular, the monitoring agents  605  in each application tier  602  in each of the sites are configured to monitor the application instances in that tier. In particular, preferably each such monitoring agent determines the health, availability and capacity of the application instances to take on additional work on the computing system wherein the particular monitoring agent  605  resides. This is depicted by flow “1.” Likewise, the monitoring agents  607  in each data tier  604  in each site are configured to monitor the data sharing members of the data source. In particular, preferably each such monitoring agent determines the health, availability and capacity of the application instances to take on additional work on the computing system wherein the particular monitoring agent  607  resides. This is depicted by flow “2.” Preferably, the respective monitoring agents  605  and  607  report their metrics to the workload manager  612 . This is depicted by flow “3.” Without intending to be limiting, the monitoring agents provide the workload manager with these metrics on a defined polling interval (e.g., once every 10 seconds), as well as immediately when an unexpected event occurs, such as an outage to or interruption of an application. The workload manager may poll the monitoring agents, or the agents may push the metrics to the workload manager. Any request-response protocol may be used for this purpose. 
     The workload manager  612  uses this information, as well as additional availability information, to signal one or more load balancer appliances  615  about how workload connections should be distributed across sites  600   a  and  600   b . This is depicted by flow “4.” Of course, if there are additional sites being load-balanced, then the load balancer appliances control the distribution across the multiple sites. 
     Referring back to  FIG. 6 , clients  625  desiring access to the workload either access the data sources via application tier in the first site  600   a , or via the application tier in the second site  600   b . This is depicted as flow “5.” For client  625  requests for access to the workload&#39;s data sources, the load balancer appliance  615  distributes connections to an application instance in the application tier  602  in the site  600  that can best handle the additional workload request (as defined in a current distribution pattern recommendation provided by the workload manager). Thus, and based on the metrics collected from the monitoring agents, when the workload manager  612  recommends site  600   a  over site  600   b , a load balancer appliance  615  routes a new client workload connection request to an application instance in the site  600   a . This is depicted by flow “6.” The application instances in site  600   a  then query one of the data sharing members in the data tier  604  in site  600   a  to access the data source. This is depicted by flow “8.” On the other hand, and once again based on the metrics collected from the monitoring agents, when the workload manager  612  recommends site  600   b  over site  600   a , the load balancer appliance  615  routes a new client workload connection request to an application instance in site  600   b . This is depicted by flow “7.” In this case, the application instances in  600   b  then queries one of the data sharing members in the data tier in site  600   b  to access the data source. This is depicted by flow “9.” 
     In this example scenario, and as described above, site  600   a  has one less application instance in its application tier than site  600   b , but site  600   a  has one more data sharing member in its data tier than does site  600   b . As noted above, this information, along with health, availability, and capacity to handle additional work, is used together by the workload manager  612  to determine distribution recommendations (a “distribution policy”). For example, assuming that all application instance and data sharing members have the same capacity for handling new workload requests, the workload manager  612  might then recommend that workload connection requests be equally distributed across the two sites. If, however, the business logic performed for this workload by the application instances on the application tier  602  consume more resources than accessing the data sources, then the workload manager is able to determine (by using capacity and instances metrics) that the site with more application instances is better able to handle workload requests. In that case, the workload manager would recommend that more workload connection requests be distributed to site  600   b  than to site  600   a . But, when the resulting data source access for this workload consumes more resources than performing the business logic on the application instances, then the workload manager is able to determine (once again, by using capacity and instances metrics) that the site with more data sharing members is better able to handle workload requests. In that case, the workload manager recommends that more workload connection requests be distributed to site  600   a  than to site  600   b.    
     Thus, the distribution policy provided by the workload manager to the load balancer appliance is based at least in part on the capacity of the application instances to process additional work relative to the capacity of the data sharing members to process additional work. 
     As noted above, the workload manager preferably takes advantage of additional availability information in formulating a current distribution policy or recommendation. This additional availability information typically includes a determination of a total number of available application instances and/or data sharing members, as the case may be. This determination preferably is “dynamic” in the sense that it may be carried out periodically, continuously, on-demand, or otherwise. Thus, in the context of the example scenario shown in  FIG. 6 , there are three (3) application instances and four (4) data sharing members configured in site  600   a , and four (4) application instances and three (3) data sharing members configured in site  600   b . As particular application instances or data sharing members (as indicated by the metrics) become unhealthy or unavailable (or as additional instances are configured), the determination of the total number of application instances and/or data sharing members then available for servicing the workload in the workload group varies, and on a dynamic basis. Preferably, and as will be described below, the workload manager  612  updates its distribution policy recommendation based on such changes. Generalizing, the workload manager updates its distribution recommendations synchronously or asynchronously, on-demand, upon changes in the metrics as measured by the monitoring agents, upon changes in the total number of available application instances and/or data sharing members as calculated by the workload manager, or upon any combination of such information and measurements. 
     Thus, the distribution policy (i.e., the workload connection request pattern) output by the workload manager typically changes, usually in a dynamic manner, to take into consideration any and all configuration and operational changes that are implemented or occurring with respect to the application instances and data sharing members within the sites. Thus, for example, assume three of the four data sharing members in the first site  600   a  either are unhealthy or unavailable, then the workload manager is able to determine (by using health, availability, and instances metrics) that the site with more data sharing members is better able to handle workload requests. In that case, the workload manager recommends that more workload connection requests be distributed to the second site  600   b  than to the first site  600   a.    
     Of course, the above-described scenarios are merely exemplary and should not be taken to limit the scope of this disclosure. 
     In a representative embodiment, the application tier is hosted by a computing system executing on a first operating system platform, while the data tier is hosted by a computing system executing on a second operating system platform. For example, the application tier is hosted on IBM Linux on System z, while the data tier is hosted on z/OS. In this example, the monitoring agent for the application tier is implemented by a management agent that executes as a separate Linux on System z guest on a virtual machine (e.g., zVM). The monitoring agent then monitors all of other Linux on System z guests and their applications on that same virtual machine LPAR. The approach in this example assumes a single workload running per Linux on System z guest. Typically, failure of the application tier results in a failure of the workload, and this is independent of the status or availability of the back-end z/OS images in the site that host the data tier. 
     The technique of this disclosure provides significant advantages. Foremost, workload groups are defined and enforced with respect to applications and data, e.g., a logical grouping of application and data tiers into a workload group. The approach enables the workload manager to monitor and control the load balancer to switch workload connections for the workload based on the health, availability and capacity of the application instances and data sharing members that comprise the workload group. The approach as described provides the particular advantage of enabling workload support across application and data tiers that reside on different operating system environments. Thus, a customer&#39;s existing investment in mainframe computing resources (e.g., the data tier) may be maintained, even as the customer migrates or implements its application front-ends in a different computing system environment. More generally, the approach herein enables a workload manager to determine how to provide load balancer appliances with workload routing recommendations across sites, thereby providing enhanced load balancing. 
     As has been described, the functionality described above may be implemented as a standalone approach, e.g., a software-based function executed by a processor, or it may be available as a service (including as a web service via a SOAP/XML interface). The particular hardware and software implementation details described herein are merely for illustrative purposes are not meant to limit the scope of the described subject matter. 
     More generally, computing devices within the context of the disclosed subject matter are each a data processing system (such as shown in  FIG. 2 ) comprising hardware and software, and these entities communicate with one another over a network, such as the Internet, an intranet, an extranet, a private network, or any other communications medium or link. The applications on the data processing system provide native support for Web and other known services and protocols including, without limitation, support for HTTP, FTP, SMTP, SOAP, XML, WSDL, UDDI, and WSFL, among others. Information regarding SOAP, WSDL, UDDI and WSFL is available from the World Wide Web Consortium (W3C), which is responsible for developing and maintaining these standards; further information regarding HTTP, FTP, SMTP and XML is available from Internet Engineering Task Force (IETF). Familiarity with these known standards and protocols is presumed. 
     The techniques described herein may be implemented in or in conjunction with various server-side architectures including simple n-tier architectures, web portals, federated systems, and the like. The techniques herein may be practiced in a loosely-coupled server (including a “cloud”-based) environment. An example of the latter environment is an Information Technology (IT) infrastructure that supports virtualization of resources. An environment of this type typically comprises host machines (HVs) (e.g., servers or like physical machine computing devices) connected to a physical datacenter network, typically via a hypervisor management VLAN. The environment typically also includes load balancers, network data switches (e.g., top-of-rack switches), firewalls, and the like. Physical servers in the environment are each adapted to dynamically provide one or more virtual machines (VMs) using virtualization technology. Multiple VMs can be placed into a single host machine and share the host machine&#39;s CPU, memory and other resources, thereby increasing the utilization of an organization&#39;s data center. Disparate applications executing within the context of such a cloud or virtualized infrastructure may take advantage of the workgroup management technique of this disclosure. 
     Still more generally, the subject matter described herein can take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment containing both hardware and software elements. In a preferred embodiment, the trusted platform module function is implemented in software, which includes but is not limited to firmware, resident software, microcode, and the like. Furthermore, the download and delete interfaces and functionality can take the form of a computer program product accessible from a computer-usable or computer-readable medium providing program code for use by or in connection with a computer or any instruction execution system. For the purposes of this description, a computer-usable or computer readable medium can be any apparatus that can contain or store the program for use by or in connection with the instruction execution system, apparatus, or device. The medium can be an electronic, magnetic, optical, electromagnetic, infrared, or a semiconductor system (or apparatus or device). Examples of a computer-readable medium include a semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk and an optical disk. Current examples of optical disks include compact disk-read only memory (CD-ROM), compact disk-read/write (CD-R/W) and DVD. The computer-readable medium is a tangible, non-transitory item. 
     The computer program product may be a product having program instructions (or program code) to implement one or more of the described functions. Those instructions or code may be stored in a non-transitory computer readable storage medium in a data processing system after being downloaded over a network from a remote data processing system. Or, those instructions or code may be stored in a computer readable storage medium in a server data processing system and adapted to be downloaded over a network to a remote data processing system for use in a computer readable storage medium within the remote system. 
     In a representative embodiment, the interfaces and utility are implemented in a special purpose computing platform, preferably in software executed by one or more processors. The software is maintained in one or more data stores or memories associated with the one or more processors, and the software may be implemented as one or more computer programs. Collectively, this special-purpose hardware and software comprises the functionality described above. 
     While the above describes a particular order of operations performed by certain embodiments of the invention, it should be understood that such order is exemplary, as alternative embodiments may perform the operations in a different order, combine certain operations, overlap certain operations, or the like. References in the specification to a given embodiment indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. 
     Finally, while given components of the system have been described separately, one of ordinary skill will appreciate that some of the functions may be combined or shared in given instructions, program sequences, code portions, and the like. 
     The techniques herein generally provide for the above-described improvements to a technology or technical field, as well as the specific technological improvements to workload management schemes, such as described above.