Abstract:
In accordance with embodiments, there are provided mechanisms and methods for communicating data between a database and a cache. These mechanisms and methods for communicating data between a database and a cache can enable improved application quality and performance, enhanced client application interaction, increased system performance, etc.

Description:
CLAIM OF PRIORITY 
       [0001]    This application is a continuation of U.S. application Ser. No. 13/049,809, filed Mar. 16, 2011, Which claims the benefit of U.S. Provisional Patent Application No. 61/314,517, filed Mar. 16, 2010, the entire contents of which are incorporated herein by reference. 
     
    
     COPYRIGHT NOTICE 
       [0002]    A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
       FIELD OF THE INVENTION 
       [0003]    One or more implementations relate generally to data communication, and more particularly to data communication between a database and a cache. 
       BACKGROUND 
       [0004]    The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions. 
         [0005]    Conventional systems commonly utilize resources located within the system to provide system-based services (e.g., applications, etc.) to one or more users, For example, a system may provide a hypertext markup language (HTML) user interface (UI) to users, where the UT utilizes a local database of the system. Unfortunately, such system-based services have been associated with various limitations. 
         [0006]    Just by way of example, certain system-based services (e.g., HTML UIs, etc.) may not have the interface flexibility, visual features, or other capabilities of system services that are run from within an internet browser (e.g., Adobe® Flash® applications, etc.). However, techniques are needed to communicate data from the system to the browser-based services. Accordingly, it is desirable to provide techniques that enable efficient and reliable data communication between system databases and browser-based services. 
       BRIEF SUMMARY 
       [0007]    In accordance with embodiments, there are provided mechanisms and methods for communicating. data between a database and a cache. These mechanisms and methods for communicating data between a database and a cache can enable improved application quality and performance, enhanced client application interaction, increased system performance, etc. 
         [0008]    In an embodiment and by way of example, a method for communicating data between a database and a cache is provided, In one embodiment, a database of a system is identified. Additionally, a cache separate from the database that is associated with an application residing within a browser is identified. Further, data is communicated between the database and the cache. 
         [0009]    While one or more implementations and techniques are described with reference to an embodiment in which communicating data between a database and a cache is implemented in a system having an application server providing a front end for an on-demand database system capable of supporting multiple tenants, the one or more implementations and techniques are not limited to multi-tenant databases nor deployment on application servers. Embodiments may be practiced using other database architectures, i.e., ORACLE®, DB2® by IBM and the like without departing from the scope of the embodiments claimed. 
         [0010]    Any of the above embodiments may be used alone or together with one another in any combination. The one or more implementations encompassed within this specification may also include embodiments that are only partially mentioned or alluded to or are not mentioned or alluded to at all in this brief summary or in the abstract. Although various embodiments may have been motivated by various deficiencies with the prior art, which may be discussed or alluded to in one or more places in the specification, the embodiments do not necessarily address any of these deficiencies. In other words, different embodiments may address different deficiencies that may be discussed in the specification. Some embodiments may only partially address some deficiencies or just one deficiency that may be discussed in the specification, and some embodiments may not address any of these deficiencies. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    In the following drawings like reference numbers are used to refer to like elements. Although the following figures depict various examples, the one or more implementations are not limited to the examples depicted in the figures. 
           [0012]      FIG. 1  illustrates a method for communicating data between a database and a cache, in accordance with one embodiment; 
           [0013]      FIG. 2  illustrates an exemplary write-behind caching architecture, in accordance with another embodiment; 
           [0014]      FIG. 3  illustrates an exemplary cache domain environment, in accordance with another embodiment; 
           [0015]      FIG. 4  illustrates an exemplary environment where a cache object is used as a wrapper for XML information, in accordance with another embodiment; 
           [0016]      FIG. 5  illustrates an exemplary environment where a cached state is refreshed from a server, in accordance with another embodiment; 
           [0017]      FIG. 6  illustrates another exemplary environment for refreshing a cached state from a server, in accordance with another embodiment; 
           [0018]      FIG. 7  illustrates a block diagram of an example of an environment wherein an on-demand database system might be used; and 
           [0019]      FIG. 8  illustrates a block diagram of an embodiment of elements of  FIG. 7  and various possible interconnections between these elements. 
       
    
    
     DETAILED DESCRIPTION 
     General Overview 
       [0020]    Systems and methods are pr vided for communicating data between a database and a cache. 
         [0021]    As used herein, the term multi-tenant database system refers to those systems in which various elements of hardware and software of the database system may be shared by one or more customers. For example, a given application server may simultaneously process requests for a great number of customers, and a given database table may store rows for a potentially much greater number of customers. 
         [0022]    Next, mechanisms and methods for communicating data between a database and a cache will be described with reference to example embodiments. 
         [0023]      FIG. 1  illustrates a method  100  for communicating data between a database and a cache, in accordance with one embodiment. As shown in operation  102 , a database of a system is identified. In one embodiment, the system may include a client, a server, a multi-tenant on-demand database system, etc. In another embodiment, the database may include data that is associated with one or more system applications. For example, the database may store one or more objects that are used by one or more applications of the system. In yet another embodiment, metadata may be stored within the database. For example, the database may contain metadata that describes one or more of the objects (e.g., describes one or more properties of an object, one or more fields of an object, the “shape” of an object, etc.) stored within the database. 
         [0024]    Additionally, it should be noted that, as described above, such multi-tenant on-demand database system may include any service that relies on a database system that is accessible over a network, in which various elements of hardware and software of the database system may be shared by one or more customers (e.g. tenants). For instance, a given application server may simultaneously process requests for a great number of customers, and a given database table may store rows for a potentially much greater number of customers, Various examples of such a multi-tenant on-demand database system will be set forth in the context of different embodiments that will be described during reference to subsequent figures. 
         [0025]    Furthermore, as shown in operation  104 , a cache separate from the database that is associated with an application residing within a browser is identified. In one embodiment, the application may be associated with the system. For example, the application may be a feature provided by the system, In another embodiment, the application may provide a service or other feature of the system. For example, the application may include a graphical approval process editor that enables customers of the system to add, remove, view, or manipulate one or more approval processes utilizing a visual user interface (UI). In another example, the approval process interface may manage a description of each approval process (e.g., by depicting a visual representation of the approval process, etc.). In yet another example, the approval process may route submitted approval processes through the system. 
         [0026]    Further still, in one embodiment, the application may run in a browser (e.g., an end-user&#39;s browser, etc.) inside a browser-based application runtime (e.g., Adobe Flash®, etc.). In another embodiment, the application may be created utilizing a software development kit associated with the browser-based application runtime (e.g. Adobe Flex®, etc.). In yet another embodiment, the cache may provide one or more components of the application with data. For example, the cache may include a client-side cache external to the system (e.g., located within the browser, etc.) and may provide one or more interface components of the application with a one or more objects from the database of the system. For instance, the cache may provide the In components of the graphical approval process editor with a view of objects of the database that comprise an approval process. In yet another embodiment, a network connection may exist between the database and the cache. 
         [0027]    Further, as shown in operation  106 , data is communicated between the database and the cache. In one embodiment, communicating the data may include sending data from the database to the cache. For example, communicating the data may include retrieving the data (e.g., one or more objects such as approval processes, etc.) from the database, compiling the data into a form recognizable by the application, and sending the data to the cache. In another embodiment, communicating the data may include sending data from the cache to the database. In still another embodiment, communicating the data may include synchronizing data between the cache and the database. 
         [0028]    Additionally, in one embodiment, communicating the data may be performed by a cache module (e.g., an application server, etc.). In another embodiment, communicating the data may be performed utilizing an application programming interface (API). For example, an API may be generated utilizing a protocol specification (e.g., simple object access protocol (SOAP), etc.), and the API may retrieve data from the database and may provide it to the cache. See, for example, U.S. patent application Ser. No. 10/870,695, Attorney Docket Number 021735-000700US, filed JUN. 16, 2004, which is hereby incorporated by reference in its entirety, and which describes exemplary techniques for exposing system database data utilizing SOAP web services. 
         [0029]    Further, in one embodiment, one or more descriptions of the data (e.g., metadata, etc.) may be obtained from the database utilizing the protocol specification. For example, the SOAP protocol may utilize an extensible markup language (XML) which may be self-describing and may provide a metadata description associated with the data to the application. Additionally, the one or more descriptions may be stored at the cache, 
         [0030]    Further still, in one embodiment, a data dictionary may be utilized to obtain the descriptions of the data retrieved from the database. For example, a universal data dictionary (UDD) may provide metadata associated with the data retrieved from the database. In this way, the UDD may be leveraged to provide metadata descriptions of the retrieved data from the database. Additionally, in one embodiment, the application may utilize the descriptions of the data to perform one or more actions associated with the data. For example, the graphical approval process editor may utilize the metadata provided by the UDD to identify and utilize approval process objects retrieved from the system database. 
         [0031]    Also, in one embodiment, the synchronizing may include saving the data in the cache at the object level (e.g., performing object-level caching of the data, etc.). For example, a one-to-one relationship may be maintained between objects stored in the database and objects stored in the cache. In another example, if changes are made to specific objects within the application (e.g., as a result of a user changing the objects utilizing the application, etc.), such changes may be temporarily stored in the cache (which may remember the relationships between data stored therein). Additionally, the specific objects that have been changed may be returned to the database of the system, and those specific objects may then be updated at the system according to the changes made in the cache. 
         [0032]    In this way, only the data that has been changed using the application may be sent independently from the rest of the data in the cache back to the database (e.g., instead of a document representing all data within the cache, etc.). Additionally, in one embodiment, one or more individual objects may be retrieved from the database to the cache, thereby resulting in more efficient cache refreshing of individual objects. In another embodiment, data in the cache may be refreshed from the database asynchronously. Additionally, in yet another embodiment, the cache may employ a proxy architecture that may preserve the data identity of data in the cache across refreshes. still another embodiment, data in the cache may be updated and written back to the database at a time chosen by the application e.g., in response to an end user selecting a “save” icon, etc.). 
         [0033]    Further, in one embodiment, a change may be made to data in the database by an entity other than the application. For example, a client running outside of the browser may access data in the database and may perform an out-of-band alteration of the data. Additionally, a copy of the data may also be stored in the cache before it is changed by the entity. In another embodiment, the copy of the data stored in the cache may be automatically updated, in response to the change made by the entity. 
         [0034]    For example, a cache representation may be created for a specific object, and code may be created that is attached to that object. Further, if out-of-band updates are made at the server, the state may automatically be changed, and the application may be notified. In this way, out-of-band changes may be automatically accounted for within the cache, thereby increasing performance and preserving data identities. 
         [0035]      FIG. 2  illustrates an exemplary write-behind caching architecture  200 , in accordance with another embodiment. As an option, the present architecture  200  may be carried out in the context of the functionality of  FIG. 1 . Of course, however, the architecture  200  may be carried out in any desired environment. The aforementioned definitions may apply during the present description. 
         [0036]    As shown, a system database  202  is in communication with an application server  204  over a network connection  216 , where the application server  204  includes a SOAP servlet  208 , Additionally, the application server  204  is in communication with a browser environment  206  that includes an application  210 . Further, the application  210  includes a client-side cache  212  and a user interface  214 . In one embodiment, the application  210  may request data from the database  202  via the SOAP servlet  208  of the application server  204 . For example, the application  210  may request data to be displayed in the browser environment  206 . 
         [0037]    Additionally, in one embodiment, in response to the request received from the application server  204 , the database  202  may return the requested data to the application server  204 . In another embodiment, the database  202  may also return metadata describing the data to the application server  204 . For example, the database  202  may also return to the application server  204  metadata describing the shape of the data (e.g., properties of the data, types of fields of the data, a type of object included within the data, dynamic fields that are included within the data, etc.). 
         [0038]    In yet another embodiment, the application server  204  may utilize a data dictionary (e.g. a UDD, etc.) to describe to the application  210  the data and metadata retrieved from the database  202 . For example, using the metadata and the data dictionary, the SOAP servlet  208  within the application server  204  may recognize the shape of data objects (e.g., approval process objects, etc.) within the data from the database  202  and may compile the data into a form usable by the application  210 . Additionally, the compiled representation of the data that is recognizable by the application  210  may be stored in the client-side cache  212 . 
         [0039]    Further, in another embodiment, the cache  212  may exist at the bottom of a typical three-tier architecture, and objects in the database may be read by the application  210 . In another embodiment, when the application  210  has loaded the database objects, they may be streamed out to the end user&#39;s browser  206  via XML, where they may be re-materialized as objects in the cache  212  (e.g., within a Grape application, etc.). 
         [0040]    In this way, the metadata and the data dictionary may be leveraged in order to translate the data retrieved from the database  202  such that data and data relationships are described and pertinent entities as well as conditions are identified. As a result, the application  210  may know what to expect when it received the data to properly utilize the data, thereby overcoming the locality of data between the database  202  and the browser environment  206 . 
         [0041]      FIG. 3  illustrates an exemplary cache domain environment  300 , in accordance with another embodiment. As an option, the present environment  300  may be carried out in the context of the functionality of  FIGS. 1-2 . Of course, however, the environment  300  may be carried out in any desired environment. The aforementioned definitions may apply during the present description. 
         [0042]    As shown, a cache domain  302  includes a plurality of cache objects  304   a - d . Further, a plurality of user interface components  306   a  and  306   b  are in communication with one or more of the cache objects  304   a - d  within the cache domain  302 . In one embodiment, the cache domain may include the organizing structure of the cache of an application running within a browser environment. In another embodiment, the cache objects  304   a - d  may provide a single, coherent view of a portion of data located in a separate system database. In yet another embodiment, the cache domain  302  may provide services by which cache objects  304   a - d  are created, refreshed, destroyed, made discoverable to the user interfaces  306   a - b , etc. 
         [0043]    Additionally, in one embodiment, client applications may only have need of a single cache domain  302  which may exist for the life of the application instance. In another embodiment, code components in the user interfaces  306   a - b  may be free to refer to and interact with one or more cache objects  304   a - d  as they might any model objects in a typical model-view-controller architecture. In yet another embodiment, cache objects  304   a - d  are also free to refer to other cache objects  304   a - d.    
         [0044]      FIG. 4  illustrates an exemplary environment  400  where a cache object is used as a wrapper for XML information, in accordance with another embodiment. As an option, the present environment  400  may be carried out in the context of the functionality of  FIGS. 1-3 , Of course, however, the environment  400  may be carried out in any desired environment. The aforementioned definitions may apply during the present description. 
         [0045]    As shown, a cache domin  402  includes a cache object  404  which serves as a proxy to a wrapped bit of state  406 . In one embodiment, the wrapped bit of state  406  may be retrieved from a server or other system. In another embodiment, the wrapped bit of state  406  may include a simple struct that represent pieces of the XML payload and which may be code generated from a web service definition language (WSDL) of a protocol (e.g., SOAP, etc.). 
         [0046]    Additionally, in one embodiment, the cache state  406  may be updated asynchronously while maintaining object identity. For example, references to and among cache object  404  and other cache objects may remain valid after the read. 
         [0047]      FIG. 5  illustrates an exemplary environment  500  where a cached state is refreshed from a server, in accordance with another embodiment. As an option, the present environment  500  may be carried out in the context of the functionality of  FIGS. 1-4 . Of course, however, the environment  500  may be carried out in any desired environment. The aforementioned definitions may apply during the present description. 
         [0048]    As shown, a cache domain  502  containing a cache object  508  is in communication with an application server  504  that includes a SOAP servlet  506 . In one embodiment, when a read to the cache domain  502  is triggered, anew version of an xml state  510  is received from a server via the application server  504  and injected into the cache object  508 . In another embodiment, the old state  512  may be discarded. In this way, a state of the cache object  508  may be effectively updated “in place.” 
         [0049]    Additionally, in one embodiment, UI components which may need to refer to some object in the data model may do so by object reference rather than by utilizing an identifier. Further, when the cache read happens, the UI components may not have to go back into the cache to look up the new version of the model object, since the object they were already pointing at may be updated in place, In this way, the design of UI code may be significantly simplified, objects may be refreshed in the cache at will (such as with asynchronous polling, etc.). 
         [0050]      FIG. 6  illustrates another exemplary environment  600  for refreshing a cached state from a server, in accordance with another embodiment. As an option, the present environment  600  may be carried out in the context of the functionality of  FIGS. 1-5 . Of course, however, the environment  600  may be carried out in any desired environment. The aforementioned definitions may apply during the present description. 
         [0051]    As shown, a cache domain  602  of an application that contains a cache object  608  is in communication with a database  606  of a system via an app server  504 . In one embodiment, when the cache object  608  is changed (e.g., as a result of end user action in a user interface, etc.), it may be marked “dirty” and may be scheduled for write-back to the database  606 . For example, at a time of the application&#39;s choosing (e.g, in response to user events, the firing of an asynchronous tinier, etc.), the “dirtied” cache object  608  may be pushed back to the database  606  of the server via XML and may be written to the database  606 . 
         [0052]    In another embodiment, “stale writes” may be detected via an optimistic concurrency mechanism. For example, update timestamps may be maintained in the cache domain  602  and may be compared with timestamps in the database  606 . 
       System Overview 
       [0053]      FIG. 7  illustrates a block diagram of an environment  710  wherein an on-demand database system might be used. Environment  710  may include user systems  712 , network  714 , system  716 , processor system  717 , application platform  718 , network interface  720 , tenant data storage  722 , system data storage  724 , program code  726 , and process space  728 . In other embodiments, environment  710  may not have all of the components listed and/or may have other elements instead of, or in addition to, those listed above. 
         [0054]    Environment  710  is an environment in which an on-demand database system exists. User system  712  may be any machine or system that is used by a user to access a database user system. For example, any of user systems  712  can be a handheld computing device, a mobile phone, a laptop computer, a work station, and/or a network of computing devices. As illustrated in  FIG. 7  (and in more detail in  FIG. 8 ) user systems  712  might interact via a network  714  with an on-demand database system, which is system  716 . 
         [0055]    An on-demand database system, such as system  716 , is a database system that is made available to outside users that do not need to necessarily be concerned with building and/or maintaining the database system, but instead may be available for their use when the users need the database system (e.g., on the demand of the users). Some on-demand database systems may store information from one or more tenants stored into tables of a common database image to form a multi-tenant database system (MTS). Accordingly, “on-demand database system  716 ” and “system  716 ” will be used interchangeably herein. A database image may include one or more database objects. A relational database management system (RDMS) or the equivalent may execute storage and retrieval of information against the database object(s). Application platform  718  may be a framework that allows the applications of system  716  to run, such as the hardware and/or software, e.g., the operating system. In an embodiment, on-demand database system  716  may include an application platform  718  that enables creation, managing and executing one or more applications developed by the provider of the on-demand database system, users accessing the on-demand database system via user systems  712 , or third party application developers accessing the on-demand database system via user systems  712 . 
         [0056]    The users of user systems  712  may differ in their respective capacities, and the capacity of a particular user system  712  might be entirely determined by permissions (permission levels) for the current user. For example, where a salesperson is using a particular user system  712  to interact with system  716 , that user system has the capacities allotted to that salesperson. However, while an administrator is using that user system to interact with system  716 , that user system has the capacities allotted to that administrator. In systems with a hierarchical role model, users at one permission level may have access to applications, data, and database information accessible by a lower permission level user, but may not have access to certain applications, database information, and data accessible by a user at a higher permission level. Thus, different users will have different capabilities with regard to accessing and modifying application and database information, depending on a user&#39;s security or permission level 
         [0057]    Network  714  is any network or combination of networks of devices that communicate with one another. For example, network  714  can be any one or any combination of a LAN (local area network), WAN (wide area network), telephone network, wireless network, point-to-point network, star network, token ring network, hub network, or other appropriate configuration. As the most common type of computer network in current use is a TCP/IP (Transfer Control Protocol and Internet Protocol) network, such as the global internetwork of networks often referred to as the “Internet” with a capital “I,” that network will be used in many of the examples herein. However, it should be understood that the networks that the one or more implementations might use are not so limited, although TCP/IP is a frequently implemented protocol. 
         [0058]    User systems  712  might communicate with system  716  using TCP/IP and, at a higher network level, use other common Internet protocols to communicate, such as HTTP, FTP, AFS, WAP, etc. In an example where HTTP is used, user system  712  might include an HTTP client commonly referred to as a “browser” for sending and receiving HTTP messages to and from an HTTP server at system  716 . Such an HTTP server might be implemented as the sole network interface between system  716  and network  714 , but other techniques might be used as well or instead. In some implementations, the interface between system  716  and network  714  includes load sharing functionality, such as round-robin HTTP request distributors to balance loads and distribute incoming HTTP requests evenly over a plurality of servers. At least as for the users that are accessing that server, each of the plurality of servers has access to the MTS&#39; data; however, other alternative configurations may be used instead. 
         [0059]    In one embodiment, system  716 , shown in  FIG. 7 , implements a web-based customer relationship management (CRM) system. For example, in one embodiment, system  716  includes application servers configured to implement and execute CRM software applications as well as provide related data, code, forms, webpages and other information to and from user systems  712  and to store to, and retrieve from, a database system related data, objects, and Webpage content. With a multi-tenant system, data for multiple tenants may be stored in the same physical database object, however, tenant data typically is arranged so that data of one tenant is kept logically separate from that of other tenants so that one tenant does not have access to another tenant&#39;s data, unless such data is expressly shared. In certain embodiments, system  716  implements applications other than, or in addition to, a CRM application. For example, system  716  may provide tenant access to multiple hosted (standard and custom) applications, including a CRM application. User (or third party developer) applications, which may or may not include CRM, may be supported by the application platform  718 , which manages creation, storage of the applications into one or more database objects and executing of the applications in a virtual machine in the process space of the system  716 . 
         [0060]    One arrangement for elements of system  716  is shown in  FIG. 7 , including a network interface  720 , application platform  718 , tenant data storage  722  for tenant data  723 , system data storage  724  for system data  725  accessible to system  716  and possibly multiple tenants, program code  726  for implementing various functions of system  716 , and a process space  728  for executing MTS system processes and tenant-specific processes, such as running applications as part of an application hosting service. Additional processes that may execute on system  716  include database indexing processes. 
         [0061]    Several elements in the system shown in  FIG. 7  include conventional, well-known elements that are explained only briefly here. For example, each user system  712  could include a desktop personal computer, workstation, laptop, PDA, cell phone, or any wireless access protocol (WAP) enabled device or any other computing device capable of interfacing directly or indirectly to the Internet or other network connection. User system  712  typically runs an HTTP client, e.g., a browsing program, such as Microsoft&#39;s Internet Explorer browser, Netscape&#39;s Navigator browser, Opera&#39;s browser, or a WAP-enabled browser in the case of a cell phone, PDA or other wireless device, or the like, allowing a user (e.g., subscriber of the multi-tenant database system) of user system  712  to access, process and view information, pages and applications available to it from system  716  over network  714 . Each user system  712  also typically includes one or more user interface devices, such as a keyboard, a mouse, trackball, touch pad, touch screen, pen or the like, for interacting with a graphical user interface (GUI) provided by the browser on a display (e.g., a monitor screen, LCD display, etc.) in conjunction with pages, forms, applications and other information provided by system  716  or other systems or servers. For example, the user interface device can be used to access data and applications hosted by system  716 , and to perform searches on stored data, and otherwise allow a user to interact with various GUI pages that may be presented to a user. As discussed above, embodiments are suitable for use with the Internet, which refers to a specific global internetwork of networks. However, it should be understood that other networks can be used instead of the Internet, such as an intranet, an extranet, a virtual private network (VPN), a non-TCP/IP based network, any LAN or WAN or the like. 
         [0062]    According to one embodiment, each user system  712  and all of its components are operator configurable using applications, such as a browser, including computer code run using a central processing unit such as an Intel Pentium® processor or the like. Similarly, system  716  (and additional instances of an MTS, where more than one is present) and all of their components might be operator configurable using application (s) including computer code to run using a central processing unit such as processor system  717 , which may include an Intel Pentium® processor or the like, and/or multiple processor units. A computer program product embodiment includes a machine-readable storage medium (media) having instructions stored thereon/in which can be used to program a computer to perform any of the processes of the embodiments described herein. Computer code for operating and configuring system  716  to intercommunicate and to process webpages, applications and other data and media content as described herein are preferably downloaded and stored on a hard disk, but the entire program code, or portions thereof, may also be stored in any other volatile or non-volatile memory medium or device as is well known, such as a ROM or RAM, or provided on any media capable of storing program code, such as any type of rotating media including floppy disks, optical discs, digital versatile disk (DVD), compact disk (CD), microdrive, and magneto-optical disks, and magnetic or optical cards, nanosystems (including molecular memory ICs), or any type of media or device suitable for storing instructions and/or data. Additionally, the entire program code, or portions thereof, may be transmitted and downloaded from a software source over a transmission medium, e.g., over the Internet, or from another server, as is well known, or transmitted over any other conventional network connection as is well known (e.g., extranet, VPN. LAN, etc.) using any communication medium and protocols (e.g., TCP/IP, HTTP, HTTPS, Ethernet, etc.) as are well known. It will also be appreciated that computer code for implementing embodiments can be implemented in any programming language that can be executed on a client system and/or server or server system such as, for example, C, C++, HTML, any other markup language, Java™, JavaScript. ActiveX, any other scripting language, such as VBScript, and many other programming languages as are well known may be used. (Java™ is a trademark of Sun Microsystems, Inc.). 
         [0063]    According to one embodiment, each system  716  is configured to provide webpages, forms, applications, data and media content to user (client) systems  712  to support the access by user systems  712  as tenants of system  716 . As such, system  716  provides security mechanisms to keep each tenant&#39;s data separate unless the data is shared, If more than one MTS is used, they may be located in close proximity to one another (e.g., in a server farm located in a single building or campus), or they may be distributed at locations remote from one another (e.g., one or more servers located in city A and one or more servers located in city B). As used herein, each MTS could include one or more logically and/or physically connected servers distributed locally or across one or more geographic locations. Additionally, the term “server” is meant to include a computer system, including processing hardware and process space(s), and an associated storage system and database application (e.g., OODBMS or RDBMS) as is well known in the art. It should also be understood that “server system” and “server” are often used interchangeably herein. Similarly, the database object described herein can be implemented as single databases, a distributed database, a collection of distributed databases, a database with redundant online or offline backups or other redundancies, etc., and might include a distributed database or storage network and associated processing intelligence. 
         [0064]      FIG. 8  also illustrates environment  710 . However, in  FIG. 8  elements of system  716  and various interconnections in an embodiment are further illustrated.  FIG. 8  shows that user system  712  may include processor system  712 A, memory system  712 B, input system  712 C, and output system  712 D.  FIG. 8  shows network  714  and system  716 .  FIG. 8  also shows that system  716  may include tenant data storage  722 , tenant data  723 , system data storage  724 , system data  725 , User Interface (UI)  830 , Application Program Interface (API)  832 , PL/SOQL  834 , save routines  836 , application setup mechanism  838 , applications servers  800   1 - 800   N , system process space  802 , tenant process spaces  804 , tenant management process space  810 , tenant storage area  812 , user storage  814 , and application metadata  816 . In other embodiments, environment  710  may not have the same elements as those listed above and/or may have other elements instead of, or in addition to, those listed above. 
         [0065]    User system  712 , network  714 , system  716 , tenant data storage  722 , and system data storage  724  were discussed above in  FIG. 7 . Regarding user system  712 , processor system  712 A may be any combination of one or more processors. Memory system  712 B may be any combination of one or more memory devices, short term, and/or long term memory. Input system  712 C may be any combination of input devices, such as one or more keyboards, mice, trackballs, scanners, cameras, and/or interfaces to networks. Output system  712 D may be any combination of output devices, such as one or more monitors, printers, and/or interfaces to networks. As shown by  FIG. 8 , system  716  may include a network interface  720  (of  FIG. 7 ) implemented as a set of HTTP application servers  800 , an application platform  718 , tenant data storage  722 , and system data storage  724 . Also shown is system process space  802 , including individual tenant process spaces  804  and a tenant management process space  810 . Each application server  800  may be configured to tenant data storage  722  and the tenant data  723  therein, and system data storage  724  and the system data  725  therein to serve requests of user systems  712 . The tenant data  723  might be divided into individual tenant storage areas  812 , which can be either a physical arrangement and/or a logical arrangement of data, Within each tenant storage area  812 , user storage  814  and application metadata  816  might be similarly allocated for each user. For example, a copy of a user&#39;s most recently used (MRU) items might be stored to user storage  814 . Similarly, a copy of MRU items for an entire organization that is a tenant might be stored to tenant storage area  812 . A UI  830  provides a user interface and an API  832  provides an application programmer interface to system  716  resident processes to users and/or developers at user systems  712 . The tenant data and the system data may be stored in various databases, such as one or more Oracle™ databases. 
         [0066]    Application platform  718  includes an application setup mechanism  838  that supports application developers&#39; creation and management of applications, which may be saved as metadata into tenant data storage  722  by save routines  836  for execution by subscribers as one or more tenant process spaces  804  managed by tenant management process  810  for example. Invocations to such applications may be coded using PL/SOQL  834  that provides a programming language style interface extension to API  832 . A detailed description of some PL/SOQL language embodiments is discussed in commonly owned co-pending U.S. Provisional Patent Application 60/828,192 entitled, PROGRAMMING LANGUAGE METHOD AND SYSTEM FOR EXTENDING APIS TO EXECUTE IN CONJUNCTION WITH DATABASE APIS, by Craig Weissman, filed Oct. 4, 2006, which is incorporated in its entirety herein for all purposes. Invocations to applications may be detected by one or more system processes, which manages retrieving application metadata  816  for the subscriber making the invocation and executing the metadata as an application in a virtual machine. 
         [0067]    Each application server  800  may be communicably coupled to database systems, e.g., having access to system data  725  and tenant data  723 , via a different network connection. For example, one application server  800   1  might be coupled via the network  714  (e.g., the Internet), another application server  800   N−1  might he coupled via a direct network link, and another application server  800   N  might be coupled by yet a different network connection. Transfer Control Protocol and Internet Protocol (TCP/IP) are typical protocols for communicating between application servers  800  and the database system, However, it will be apparent to one skilled in the art that other transport protocols may be used to optimize the system depending on the network interconnect used. 
         [0068]    In certain embodiments, each application server  800  is configured to handle requests for any user associated with any organization that is a tenant. Because it is desirable to he able to add and remove application servers from the server pool at any time for any reason, there is preferably no server affinity for a user and/or organization to a specific application server  800 . In one embodiment, therefore, an interface system implementing a load balancing function (e.g., an F5 Big-IP load balancer) is communicably coupled between the application servers  800  and the user systems  712  to distribute requests to the application servers  800 . In one embodiment, the load balancer uses a least connections algorithm to route user requests to the application servers  800 . Other examples of load balancing algorithms, such as round robin and observed response time, also can be used. For example, in certain embodiments, three consecutive requests from the same user could hit three different application servers  800 , and three requests from different users could hit the same application server  800 . In this manner, system  716  is multi-tenant, wherein system  716  handles storage of, and access to, different objects, data and applications across disparate users and organizations. 
         [0069]    As an example of storage, one tenant might be a company that employs a sales force where each salesperson uses system  716  to manage their sales process. Thus, a user might maintain contact data, leads data, customer follow-up data, performance data, goals and progress data, etc., all applicable to that user&#39;s personal sales process (e.g., in tenant data storage  722 ). In an example of a MTS arrangement, since all of the data and the applications to access, view, modify, report, transmit, calculate, etc., can be maintained and accessed by a user system having nothing more than network access, the user can manage his or her sales efforts and cycles from any of many different user systems, For example, if a salesperson is visiting a customer and the customer has Internet access in their lobby, the salesperson can obtain critical updates as to that customer while waiting for the customer to arrive in the lobby. 
         [0070]    While each user&#39;s data might be separate from other users&#39; data regardless of the employers of each user, some data might be organization-wide data shared or accessible by a plurality of users or all of the users for a given organization that is a tenant. Thus, there might be some data structures managed by system  716  that are allocated at the tenant level while other data structures might be managed at the user level. Because an MTS might support multiple tenants including possible competitors, the MTS should have security protocols that keep data, applications, and application use separate. Also, because many tenants may opt for access to an MTS rather than maintain their own system, redundancy, up-time, and backup are additional functions that may be implemented in the MTS. In addition to user-specific data and tenant specific data, system  716  might also maintain system level data usable by multiple tenants or other data. Such system level data might include industry reports, news, postings, and the like that are sharable among tenants. 
         [0071]    In certain embodiments, user systems  712  (which may be client systems) communicate with application servers  800  to request and update system-level and tenant-level data from system  716  that may require sending one or more queries to tenant data storage  722  and/or system data storage  724 . System  716  (e.g., an application server  800  in system  716 ) automatically generates one or more SQL statements (e.g., one or more SQL queries) that are designed to access the desired information. System data storage  724  may generate query plans to access the requested data from the database. 
         [0072]    Each database can generally be viewed as a collection of objects, such as a set of logical tables, containing data fitted into predefined categories. A “table” is one representation of a data object, and may be used herein to simplify the conceptual description of objects and custom objects. It should be understood that “table” and “object” may be used interchangeably herein. Each table generally contains one or more data categories logically arranged as columns or fields in a viewable schema. Each row or record of a table contains an instance of data for each category defined by the fields, For example, a CRM database may include a table that describes a customer with fields for basic contact information such as name, address, phone number, fax number, etc. Another table might describe a purchase order, including fields for information such as customer, product, sale price, date, etc. In some multi-tenant database systems, standard entity tables might be provided for use by all tenants. For CRM database applications, such standard entities might include tables for Account, Contact, Lead, and Opportunity data, each containing pre-defined fields. It should be understood that the word “entity” may also be used interchangeably herein with “object” and “table”. 
         [0073]    In some multi-tenant database systems, tenants may be allowed to create and store custom objects, or they may be allowed to customize standard entities or objects, for example by creating custom fields for standard objects, including custom index fields. U.S. patent application Ser. No. 10/817,161, filed Apr. 2, 2004, entitled “Custom Entities and Fields in a Multi-Tenant Database System”, and which is hereby incorporated herein by reference, teaches systems and methods for creating custom objects as well as customizing standard objects in a multi-tenant database system. In certain embodiments, for example, all custom entity data rows are stored in a single multi-tenant physical table, which may contain multiple logical tables per organization. It is transparent to customers that their multiple “tables” are in fact stored in one large table or that their data may be stored in the same table as the data of other customers. 
         [0074]    While one or more implementations have been described by way of example and in terms of the specific embodiments, it is to be understood that one or more implementations are not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.