Abstract:
The system of the present invention having a first module ( 20 ) for storing information describing a plurality of data objects ( 150, 160 , and  170 ), attributes of each of the plurality of data objects, and relationships therebetween; a second module ( 15 ) for accepting and processing user queries generating first results data, the first results data including the information describing the plurality of data objects stored in the first module; and a third module ( 85 ) responsive to the second module ( 15 ) for generating second results data using the first results data, the second results data including the information contained in the plurality of data objects. The method of the present invention having the steps of providing data which describes the plurality of data objects, attributes of the plurality of data objects, and relationships therebetween; providing at least one procedure operable to build a query specific to at least one of the plurality of data object; accepting user requests querying the data; updating a first results file in response to the user requests; generating the query specific to at least one of the plurality of data objects with at least one procedure in response to the first results file; executing the query specific to at least one of the plurality of data objects; and generating a second results files in response to the executing step which includes information contained within at least one of the plurality of data objects.

Description:
This application is related to co-pending application Ser. No. 07/921,826 filed Jul. 29, 1992. 
    
    
     BACKGROUND OF THE INVENTION 
     In the information age, one of the most significant challenges facing business is the management of ever increasing amounts of information across increasingly complex and varied environments. As the competitive environment in which the business operates expands across the globe, the speed and ease of access to this information becomes critical. From a storage and processing standpoint, significant advances in computing hardware, including computer memory and computer processors, have kept pace with the increasing amounts of information required in day-to-day business operations. However, these advances in computing hardware are in part responsible for the increasingly complex and varied environments in which the information is found. 
     One reason that a variety of platforms are used to store and process data is that as business expands and competition increases, control is decentralized so that decisions can be made quickly by each business entity using local information. As a result of the decentralization of the business decision making process, the mainframe processors, previously the only platform on which to handle high volume information processing, are downsized to or integrated with local minicomputers and workstations. Along with the local minicomputers and workstations come a variety of software tools specific to that platform to assist in the processing of information. 
     Localized processing capability generally means even more information is generated but, the additional information and local changes to existing information may not be available throughout other areas of the business system. 
     One solution is to simply duplicate all information across all platforms. This solution, however means wasted resources in that if all of the duplicated information is not needed, the space could have been used to store other information. Also, duplication of information across multiple platforms also means that the information must be updated on each platform. Another solution is to provide access, i.e., though a network, to every other platform. The problem with this solution, however, is that each platform must then know how to operate under the systems of every other platform in order to take advantage of the availability of that platform&#39;s information. One platform, for example, may be a minicomputer using an Oracle database and another platform may be a mainframe using IBM&#39;s Database 2 (DB2). 
     What is needed is a method and system for managing access to a plurality of data objects located across a variety of platforms which provides quick, easy access to the information contained therein. 
     SUMMARY OF THE INVENTION 
     One embodiment of the system of the present invention includes an information access encyclopedia, or information repository, for selecting, updating, creating and deleting information describing and information included in a plurality of data objects across a variety of platforms which insulates users from the technical complexity of the platform on which the data resides. This embodiment of the information access encyclopedia of the present invention comprises first means for storing the information describing the plurality of data objects; second means for iteratively accepting and processing user queries based on previous queries of the information describing the plurality of data objects stored in the first means generating first results data; and third means responsive to the second means for generating second results data using the first results data. The second results data includes the information contained in the plurality of data objects. 
     One embodiment of the method of the present invention includes the steps of providing data which describes the plurality of data objects, attributes of the plurality of data objects, and relationships therebetween; providing at least one procedure operable to generate a query specific to at least one of the plurality of data object; iteratively accepting user queries based on the results of previous queries on the data; updating a first results file in response to the user queries; generating the query specific to at least one of the plurality of data objects with at least one procedure in response to the first results file; executing the query specific to at least one of the plurality of data objects; and generating a second results files in response to the executing step which includes information contained within at least one of the plurality of data objects. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention, reference may be made to the accompanying drawings, in which: 
     FIG. 1 is a block diagram of one embodiment of the system of the present invention; 
     FIG. 2 shows an entity relationship diagram illustrating how data stored in one embodiment of the system and method of the present invention is modeled; 
     FIG. 3 is an entity relationship diagram illustrating how data in an exemplary system is modeled so that it can be stored in one embodiment of the system and method of the present invention; 
     FIG. 4 illustrates a data object table which includes information describing objects accessible through one embodiment of the system and method of the present invention; 
     FIG. 5 illustrates an attribute object table which includes information describing attributes of the objects included in the data object table of one embodiment of the system and method of the present invention; 
     FIG. 6 illustrates a relationship object table which includes information describing relationships between objects, attributes and relationships in one embodiment of the system and method of the present invention; and 
     FIG. 7 illustrates the fields included in each of four implemented relationship tables (one for one-to-one relationships, one for one-to-many relationships, one for many-to-one relationships and one for many-to-many relationships) which include data describing implemented relationships in one embodiment of the system and method of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The system and method of the present invention provides an information access encyclopedia (IAE), or information repository, for managing access to a plurality of data objects located across a variety of platforms while insulating users from the technical complexities of the platforms on which the data objects reside, i.e., providing a seamless interface. The system and method of the present invention is implemented, for example, using an object oriented database management system (OODBMS) or a relational database management system (RDBMS) on a general purpose digital computer which is connected, for example, through a network to the various platforms on which the data resides and at which access to that data is needed. In particular, the system and method of the present invention implemented using an OODBMS takes advantage of inheritance, multiple inheritance, relationship definition (complex objects) and object identifier (OID) generation features provided by the OODBMS. Each of these features can also be implemented using the RDBMS approach but, with an increase in system size and complexity. 
     One embodiment of the present invention is illustrated generally in FIG.  1 . FIG. 1 shows an IAE  10  which includes an application programming interface (API)  15 , an IAE database  20  and a data object interface  80 . IAE  10  provides access to the data stored in exemplary data objects  150 ,  160  and  170 . Exemplary data objects  150 ,  160  and  170  can represent program files, text files, databases, etc. or any combination of program files, text files, databases, etc., depending upon the particular application. 
     Not only do exemplary data objects  150 ,  160  and  170  represent different forms of data, but they also represent different forms of data on different platforms. For example, exemplary data object  150  can represent a database implemented using IBM&#39;s DB 2  on a mainframe while exemplary data object  160  represents a file directory structure on a microcomputer and exemplary data object  160  is an accounting system on a minicomputer. 
     Under the system and method of the present invention, components of each of the exemplary data objects are described in IAE database  20 . This descriptive information is browsed or navigated using API  15 . API  15  provides easy access to the data through a series of generalized query commands which are independent of the type of data and of the platform on which the data is stored. In processing these query commands, API  15  uses of its knowledge of the structure of IAE database  20  and of how data in IAE database  20  is modeled to browse or navigate IAE database  20 . Results of the browsing or navigating are then used by APIClass  85  to provide access to the data stored in or represented by exemplary data objects  150 ,  160  and  170  by building queries specific to exemplary data objects  150 ,  160  and  170 . APIClass  85  also generates specialized execution requests specific to the platform on which exemplary data objects  150 ,  160  and  170  reside to process those specific queries. The access methods used by APIClass  85  are transparent to the user. The routines needed to perform both the specialized query generation and the specific platform execution command generation functions are provided by the user responsible for setting up IAE  10  whenever a data object is added to IAE  10 . Thus, to access the data in any of the exemplary data objects  150 ,  160  and  170 , the user need only execute the generalized query commands provided by API  15 . 
     Through API  15 , applications using the IAE  10  can accomplish two tasks. First, the generic nature of API  15  and of the IAE database  20  allows immediate visibility of changes to exemplary data objects  150 ,  160  and  170  and of additions of other data objects to those applications using IAE  10 . Furthermore, the generic query and update provided by API  15  and processed by APIClass  85  eliminate the need for duplicating methods for accessing each exemplary data object  150 ,  160  and  170  for each application interfacing with exemplary data objects  150 ,  160  and  170 . Without API  15  and APIClass  85 , these methods are provided by each of the applications requesting access to the information included in exemplary data objects  150 ,  160  and  170 . 
     In order to include an exemplary data object  150 ,  160  or  170  in the IAE  10  of the present invention, data representing and/or describing exemplary data object  150 ,  160  or  170  must be entered in IAE database  20 . Data entered in IAE database  20  is modeled as shown in the entity relationship diagram (ERD) at  200  in FIG.  2 . The ERD  200  includes three object types: data object type  205 , relationship object type  210  and attribute object type  220 . Each of these object types are implemented as tables in one embodiment of the system of the present invention as shown in FIG.  1 . 
     Data object type  205  is implemented as data object table  22  shown in FIG.  1 . The data object table  22  includes the fields, shown in FIG. 4, Name  412  and OID  413 . Name  412  is a character field which identifies the object described in IAE  10 . OID  413  is a numerical field which identifies each instance of data object table  22 . 
     Attribute object type  220  is implemented as the attribute object table  24  in FIG.  1 . Attribute object table  24  includes the fields, as shown in FIG. 5, name  540 , OID  542  and sort sequence  544 . Each record in attribute object table  24  describes an attribute of an object described in data object table  22 . 
     Relationship object type  210  is implemented as the relationship object table  26  shown in FIG.  1 . Relationship object table  26  includes the fields, as shown in FIG. 6, relationship path name  630 , source OID  632 , destination OID  634 , OID  636 , primary OID  638 , secondary OID  640 , source cardinality  642 , destination cardinality  644 , source optionality  646 , destination optionality  648 , source implemented table  650  and destination implemented table  652 . Records in relationship object table  26  describe logical connections between the object records stored in data object table  22 , the attribute records stored in attribute object table  24  and the relationship records stored in relationship object table  26 . The logical connections are shown in FIG. 2 at  232 ,  234 ,  236 ,  238 ,  240 ,  242  and  244 . 
     Each logical connection is represented by two records or instances in relationship object table  26  so that a connection may be traversed in either direction by API  15 . Each record or instance is referred to as a relationship path and represents one logical relationship between the two object types it connects. Each relationship path is referred to by its relationship path name  630  and connects the object represented by the field source OID  632  to the object represented by the field destination OID  634  in the relationship object table  26 . One of the relationship paths is designated as primary and the other relationship path is designated as secondary. If a record in relationship object table  26  represents a primary relationship path, then the field secondary OID  640  specifies which record in relationship object table  26  represents the corresponding secondary relationship path. If the relationship in relationship object table represents a secondary relationship path, then the field primary OID  638  specifies which record in relationship object table  26  represents the corresponding primary relationship path. 
     The ERD  200  further models the cardinality and the optionality of the relationships between data object type  205 , relationship object type  210  and attribute object type  220 . 
     The cardinality of a relationship between objects, relationships and attributes provides an indication of how many of each are members in the relationship. The cardinality of a relationship is either one-to-one (1-1), one-to-many (1-M), many-to-one (M-1) or many-to-many (M-M). Depending upon the application, data for any of the one-to-one, one-to-many, many-to-one or many-to-many relationships may be included in an external data source or in the corresponding IAE  10  implemented relationship table  28   a ,  28   b ,  28   c  or  28   d . The field source implemented table  648  in FIG. 6 specifies where the source object data for the particular relationship is located. The field destination implemented table  650  specifies where the destination object data for the particular relationship is located. 
     If the actual data is stored in the IAE  10 , then, depending upon the cardinality of the relationship, the relationship data is stored in one version of the implemented relationship tables  28   a ,  28   b ,  28   c  or  28   d . One-to-one relationship data is implemented in the 1-1 implemented relationship table  28   a  shown in FIG. 1, one-to-many relationship data is implemented in the 1-M implemented relationship table  28   b  shown in FIG. 1, many-to-one relationship data is implemented in the M-1 implemented relationship table  28   c  shown in FIG.  1  and many-to-many relationship data is implemented in the M-M implemented relationship table  28   d.    
     The cardinality of a relationship is illustrated, for example, at  232   a  and at  232   b  in FIG.  2 . The single bar at  232   a  indicates that one data object type  205  is related to many, as shown by the three bars at  232   c , relationship object types  210 . Thus, the relationship illustrated at  232  between data object type  205  and relationship object type  210  is a one-to-many (1-M) relationship. Relationships in an ERD, however, may be traversed in either direction. In other words, the relationship illustrated at  232  from data object type  205  to relationship object type  210  is distinct from the relationship illustrated at  232  from relationship object type  210  to data object type  205 . The second relationship, from relationship object type  210  to data object type  205 , has its own cardinality. The relationship illustrated at  232  between relationship object type  210  and data object type  205  is a many-to-one (M-1) relationship. 
     The optionality of a relationship between object types, relationship types and attribute types specifies whether or not that particular relationship must be defined at creation of the object. If a relationship is optional for an object then no data describing that relationship need be entered in IAE database  20  when an object instance is created. If a relationship is mandatory, then that relationship must be instantiated when the object is instantiated. As with cardinality, optionality of a relationship is directional. For example the relationship at  232  from data object type  205  to relationship object type  210  is mandatory. Therefore, each relationship instance must specify a source object type  205  and a destination object type  205 . However, the relationship at  232  from relationship object type  210  to data object type  205  is optional, as shown the circle at  232   b.    
     As an example, FIG. 3 illustrates, at  300 , an exemplary order entry database system which is modeled for access through the system and method of the present invention. The exemplary order entry database system  300  in FIG. 3 includes the data objects sales contact  301 , product  303 , order  305  and order line  307 . Sales Contact  301  is a table which includes information describing the customer base of an entity which uses exemplary order entry database system  300 . Sales Contact  301  includes the fields Sales_Contact_Name and Sales_Contact_ID. Product  303  is a table which includes information describing products available for ordering through exemplary order entry database system  300 . Product  303  includes the fields Product_Name and Product_Type. Order  305  is a table which includes information describing orders that have been made through the exemplary order entry database system  300 . Order  305  includes the field Order_ID. Order Line  307  is a table which includes information describing each entry line of an order described in Order  305 . Order Line  307  includes the fields Order_ID, Product_Name and Product —Type.    
     In order to provide access to the exemplary order entry database system  300  through the IAE  10 , the user initializes the system by first entering a record in object table  22  for each of the tables (sales contact  301 , product  303 , order  305  and order line  307 ) of the exemplary order entry database system  300  as shown at lines  408  through  411  in FIG.  4 . Next, each attribute or fields of each of the tables in exemplary order entry database system  300  is described in a record in attribute table  24  as shown at lines  523  through  531  in FIG.  5 . 
     FIG. 3 also illustrates the logical connections which relate the objects or tables which make up exemplary order entry database system  300 . Each connection is implemented as two relationship paths each represented by a relationship path name. As shown in FIG. 3, sales contact  301  is related to product  303  by the many-to-many relationship path shown at  310  with relationship path name “sells.” The relationship path at  310  also shows that product  303  is related to sales contact  301  by a many-to-many optional relationship with relationship name “sold by.” These relationship paths between data objects are descriptive of the functional connection between objects. As the relationship at  301  in FIG. 3 illustrates, a contact in sales contact  301  sells products in product  303  and the products in product  303  are sold by the contacts in sales contact  301 . 
     Thus, the next step in providing access to exemplary order entry database system  300  through IAE  10  is to describe each of the relationship paths between the objects which comprise exemplary order entry database system  300  as a record in the relationship object table  26 . The records describing the relationships shown in FIG. 3 are illustrated in FIG. 6 at lines  615  through  624 . The relationships shown in FIG. 3 could also be implemented outside the IAE  10  in an intersection table Sales Contact/Product, not shown, which includes the fields Sales_Contact_Name, Sales_Contact_ID, Product_Name and Product_Type. Thus, the user could navigate between the objects Sales_Contact  301  and Product  303  by looking up either the Sales_Contact_ID or the Product_Name in the intersection table. 
     Another method of describing relationships between objects is illustrated in FIG. 3 at  318  in the one-to-many relationship from order  305  to order line  307  and at  316  in the one-to-many relationship from product  303  to order line  307 . Since the relationships shown at  316  and at  318  are one-to-many relationships, the fields Order_ID and Product_Name can be included in each instance of order line  307  instead of in one of the implemented relationship table  28   a ,  28   b ,  28   c  or  28   d  and instead of in an intersection table. 
     Finally, data implementing the relationships described in relationship object table  26  is entered into IAE  10 . The data source is designated by the field source implemented table  650  and the destination data source is designated by the field destination implemented table  652 . If the implemented relationship data is stored externally, then implementing field names and field types are also required. If the implemented relationship data is stored internally in IAE  10 , then the data is entered either in the one-to-one implemented relationships table  28   a , the one-to-many implemented relationships table  28   b , the many-to-one implemented relationships table  28   c  or the many-to-many implemented relationships table  28   d , based upon the cardinality of the relationship. Whether the implemented relationship data is stored external or internal and what that implemented relationship data is depends upon the application. 
     In one embodiment of the system and method of the present invention, meta data (data other than raw data, i.e., data describing the IAE  10  itself) is also stored in IAE  10 . API  15  uses this meta data to navigate IAE database  20  while processing the generalized queries from the user. A first results file, including data from IAE database  20 , is generated and is then used to build specialized query statements accessing the data stored in exemplary data objects  150 ,  160  and  170 . The meta data stored in and describing IAE  10  includes instances of data object table  22  which describe data objects of IAE  10  (i.e., lines  401  through  407  in FIG.  4 ), instances of attribute object table  24  which further describe instances of data object table  22  (i.e., lines  501  through  522  in FIG. 5) and instances of relationship object table  26  which describe the logical connections or relationships which associate instances of data object table  22 , instances of attribute object table  24  and instances of relationship object table  26  (i.e., lines  601  through  614  in FIG.  6 ). This recursive nature of the IAE  10  further supports navigation by API  15  through other data objects stored in the IAE  10 . 
     While the relationships are classified as either optional or mandatory, to fully implement the IAE  10  as a self-describing database each relationship must be known to the IAE  10  schema access software. Furthermore, because these relationships define the structure of IAE  10  meta data, they should not be exposed to an application by any IAE  10  discovery or navigation function. Also, this embodiment of the system and method of the present invention relies on these relationships being implemented as named. 
     The embodiment of the system of the present invention, illustrated in FIG. 1, includes the IAE  10  meta-data stored in IAE Database  20 . IAE Database  20  includes object data table  22 , attribute data table  24 , relationship data table  26 , 1-1 implemented relationships data table  28   a , 1-M implemented relationships data table  28   b , M-1 implemented relationships data table  28   c  and M-M implemented relationships data table  28   d.    
     For each implementation of the relationships described in relationship data table  26 , one record is included in either the 1-1 implemented relationships data table  28   a , the 1-M implemented relationships data table  28   b , the M-1 implemented relationships data table  28   c  or the M-M implemented relationships data table  28   d , depending upon the cardinality of the relationship. The fields included in the 1-1 implemented relationships data table  28   a , the 1-M implemented relationships data table  28   b , the M-1 implemented relationships data table  28   c  and the M-M implemented relationships data table  28   d  are, as shown in FIG. 7, a source OID  701 , a relationship OID  703  and a destination OID  705 . Each of the relationships data tables  28   a ,  28   b ,  28   c  and  28   d  controls the cardinality of their members using indexes on the three fields included in each of the implemented relationships data tables  28   a ,  28   b ,  28   c  and  28   d.    
     To enforce 1-1 cardinality on relationships, represented by the relationship OID  703 , between the source object and the destination object, represented by the source OID  703  and the destination OID  705 , respectively, 1-1 implemented relationships data table  28   a  includes two indexes. One index is on the source OID  701  and the relationship OID  703 . The other index is on the destination OID  705  and the relationship OID  703 . 
     To enforce 1-M cardinality on relationships, represented by the relationship OID  703 , between the source object and the destination object, represented by the source OID  701  and the destination OID  705 , respectively, 1-M implemented relationships data table  28   b  includes an index on the destination OID  705  and the relationship OID  703 . 
     To enforce M-1 cardinality on relationships, represented by the relationship OID  703 , between the source object and the destination object, represented by the source OID  701  and the destination OID  705 , respectively, M-1 implemented relationships data table  28   c  includes an index on source OID  701  and relationship OID  703 . 
     To enforce M-M cardinality on relationships, represented by the relationship OID  703 , between the source object and the destination object, represented by the source OID  701  and the destination OID  705 , respectively, M-M implemented relationships data table  28   d  includes an index on the source OID  701 , the relationship OID  703  and the destination OID  705 . 
     In implemented relationships data tables  28   a ,  28   b ,  28   c  and  28   d , only the primary relationship path is implemented. To search the secondary relationship path, the record corresponding to the primary relationship path in the implemented relationships data tables  28   a ,  28   b ,  28   c  and  28   d  is read in reverse. For example, the destination OID  705  is read for the source OID  701  and the source OID  701  is read for the destination OID  705 . Whether a relationship path is primary or secondary is indicated by the fields primary OID  636  and secondary OID  638 . 
     Once the data to be accessed is modeled in IAE  10 , API  15  controls the access to the data by accepting and processing user requests for the data. Before any processing is done by IAE  10 , IAE DBInit  42  establishes a connection with the IAE database  20 . The specific database and server location is which contain IAE database  20  obtained from a userid profile. 
     Once a connection is established with IAE database  20 , IAE Tranlnit  52  establishes a transaction session under the specified database connection to IAE Database  20 . All database activity must be done under the scope of the specified transaction. 
     At this point, the user navigates through IAE database  20  to determine the objects, attributes of those objects, and relationships between those objects and attributes which are available for use in generating queries on the data in the IAE database  20 . The functions for navigating IAE database  20  include IAE Discover  32 , IAE DiscoverAttribute  34  and IAE Discover Relationship  36 . 
     Generally, navigation starts with IAE Discover  32  which returns information about the objects included in object data table  22 . The information returned includes a non-persistent object handle which used in subsequent discover and navigation queries. As noted earlier, meta data describing the IAE  10  is not accessible through navigation commands. Once the objects stored in IAE  10  are known, the user can then select a particular object(s) and then navigate either the attributes, stored in attributes data table  24 , associated with that object(s) or the relationships, stored in relationship data table  26 , associated with the selected object(s). 
     To navigate the attributes associated with the selected object(s), the function IAE DiscoverAttribute  34  returns all attributes and descriptive attribute data for the specified object handle. 
     To navigate the relationships associated with a selected object, the function IAE DiscoverRelationship  36  returns all relationships and descriptive relationship data for the specified object. A relationship through which to continue navigation may then be chosen from the returned relationships and the user is then given another object handle. By iteratively continuing in this manner, all data accessible through the IAE  10  may be navigated. 
     Various SQL commands or requests are also available to the user during the navigation of the data accessed through the IAE  10 . These requests include select, create, update and delete. In an OODBMS implementation of the present invention, as discussed below, the processing of each of these requests involves specialized class structures which take advantage of the inheritance, multiple inheritance, relationship definitions (complex objects) and OID generation features found in an OODBMS. 
     Within the transaction initiated using IAE Tranlnit  52 , a data object on which to process query commands is selected and Init  62  establishes an IAE session under which these processes are performed. Within this session, all information necessary to access the IAE Database  20  for the specified data object is collected. In this implementation of the present invention, Make APIClass  64  is called by IAE Init  62  and creates an instance of APIClass  85  and sets the object name and desired function (select, create, update or delete). Before the desired function requested by the query is actually executed, other functions within IAE APIClass  60  are executed to set up the environment. These pre-processing functions include IAE SetAttribute  66 , IAE SetWhere  70 , and IAE Set Update  74 . 
     IAE SetAttribute  66  is used to iteratively specify the attributes to be selected by a select request. Each call specifies an attribute (referenced by its handle), an optional sort sequence and a sort order. SetAttribute  68  is called by IAE SetAttribute  66  and maintains an array of the requested attributes and data value addresses in the user&#39;s address space. 
     IAE SetWhere  70  iteratively specifies the selection or “where” criteria to be used by all select, update and delete requests. This function specifies attributes (by handle), their comparative values and relational operators as well as conjunctive operators such as “AND” and “OR.” IAE SetWhere  70  is also used to select instances of a specified object by relationship. In this case, the parameter Operator has a value of “OP_ASSOCIATE,” the parameter WhereHandle is a relationship handle instead of an attribute handle, and the parameter Value is the OID (object identifier) to be used in the selection criteria. SetWhere  72  is called by IAE SetWhere  70  and collects attribute-operator-value triples used in IAE selection criteria. Valid operators used by IAE SetWhere  70  include “=”, “&lt;=”, “&gt;=”, “&lt;&gt;”, “&lt;”, “&gt;”, “ASSOCIATE” and “DISASSOCIATE.” 
     IAE SetUpdate  74  iteratively specifies the values to be used by an update or create request. IAE SetUpdate  74  specifies attributes (by handle) and their value. IAE SetUpdate  74  is also used to create or delete relationships between object instances. In this case, the parameter Operator has a value of “OP_ASSOCIATE” or “OP_DISASSOCIATE”, the parameter UpdateHandle is a relationship handle rather than an attribute handle and the parameter Value is the OID (object identifier) to be associated with (or disassociated from) the specified object instances. SetUpdate  76  is called by IAE SetUpdate  74  and collects relationship OID-OID pairs used when associating or disassociating one object instance with or from another object instance. 
     IAE Apply  78  then generates a database query using the information supplied by the functions IAE SetAttribute  66 , IAE SetWhere  70  and IAE SetUpdate  74 . The query is in the form of a standard query language (SQL) statement, represented by a statement handle which is used by other functions that need to access the generated statement. For create requests only, IAE Apply  78  returns the OID (object identifier) of the generated object instance. Apply  80  is called by IAE Apply  78  in generating the SQL request to access the needed data included in exemplary data objects  150 ,  160  and  170 . 
     Just as IAE DBInit  42  establishes a connection to IAE database  20 , DBInit  102  establishes a connection between the IAE  10  and each of the underlying DBMS&#39;s represented by exemplary data objects  150 ,  160  and  170 . DBInit  102  also returns necessary semantics for communicating with the selected underlying DBMS including a DBMS handle used by Tranlnit  112  of TransClass  110 . 
     Thus, for processing queries on exemplary data objects  150 ,  160  and  170  generated by IAE Apply  78 , Tranlnit  112  establishes a transaction class instance which defines a transaction associated with the current database connection established by DBInit  102 . 
     In order to process the requests generated by API  15 , APIClass  85  uses the data supplied through the previous navigation or discovery of the objects, attributes and relationships in IAE database  20 . With these results, navigation or discovery of data in exemplary data objects  150 ,  160  or  170  is performed. Any data stored in IAE database  20  which is needed to access the data stored in exemplary data objects  150 ,  160  or  170  is retrieved through functions which include Discover  92 , GetAttributes  94  and GetRelationship  96 . The operation of these functions is similar to the operation of IAE Discover  32 , IAE DiscoverAttribute  34  and IAE DiscoverRelationship  36 . 
     The function SelectClass  132  processes a select request by the user. In an OODBMS implementation of the present invention, the processing done by SelectClass  132  includes creating a new instance of a class Select, not shown, allocating a new instance of a class called CommaThings which will include a list of attributes to be selected and corresponding sort criteria and allocating a new instance of a class called Table, not shown, which will include a list of “where” criteria to be used by the select request. 
     The function CreateClass  134  processes a create request by the user. The processing done by CreateClass  134  includes creating a new instance of a class called Create, and allocating a new instance of the class CommaThings which will include list of the attributes to be created. 
     The function UpdateClass  136  processes an update request by the user. The processing done by UpdateClass  136  includes creating a new instance of a class Update, allocating a new instance of the class CommaThings which will include a list of attributes and associated values to be changed, and allocating a new instance of a class Table which will include a list of “where” criteria used by the update request. 
     The function DeleteClass  138  processes a delete request by the user. The processing done by DeleteClass  138  includes creating a new instance of a class Delete, and allocating a new instance of the class Table which will include a list of “where” criteria used by the delete request. 
     APIClass  85  includes, as included in API  15 , the process of setting up the environment in which the second query is executed through a collection of functions. These functions include SetObject  140 , SetAttribute  142 , SetUpdate  144 , Set Create  146  and SetWhere  148 . SetObject  140  set the name of the data object instance to be acted upon. SetAttribute  142  specifies one attribute and associated sort criteria used by an instance of the class Select. SetUpdate  144  specifies one attribute-value-data type triple used by the class Create or Update. SetCreate  146  specifies the name of the IAE  10  data object to create. SetWhere  148  specifies one operator-attribute-value triple used by the class Select, Delete or Update. 
     Format  150  specifies how the information from the functions SetObject  140 , SetAttribute  142 , SetUpdate  144 , SetCreate  146  and SetWhere  148  is expanded into a database query statement specific to at least one of the data objects. Using this information, Format  150  formats the query statement and then stores the generated query statement in a query buffer. The format of the query statement generated by Format  150  varies from the simple case to the complex case depending upon the query command received from API  15  and upon the underlying DBMS which processes the query statement. The procedure or procedures executed to generate the specific query are provided by the user responsible for setting up IAE  10 . Generation and execution of the query specific to the exemplary data object  150 ,  160  or  170  are transparent to the user. 
     The user continues processing queries within the specified transaction and makes no changes to the underlying DBMS until a Commit command is executed. Commit  114  processes the commit command by applying to the underlying DBMS all update requests made under the current transaction. The current transaction is then cleared and remains active for further activity. Rollback  116 , on the other hand, discards all update requests made but not yet applied through Commit  114  under the current transaction. The transaction remains active for further activity. 
     SavePoint  118  defines a marker or starting point inside the specified transaction class instance from which updates and changes are stored. The data is stored temporarily in memory under a currently active transaction until a Commit  114  command is executed. With the Commit  114 , the data is stored to the corresponding permanent file. Save points are used to maintain IAE data consistency during complex updates such as relationship instantiation or during instance deletes. 
     RollbackSavePoint  120  discards all updates made under the current SavePoint. Such updates may only be committed via the transaction scoped Commit  114 . After RollbackSavePoint  120  finishes processing, the transaction remains active for further activity. 
     Execute  122  passes the generated query statement (created by Format  150  of Schema Access  130 ) to the underlying DBMS and returns a handle to the results file generated by the executed query statement. 
     Bind  124 , for select queries, associates a requested attribute with a specified address in the user&#39;s address space. 
     Fetch  126 , for select queries, is used to fetch result data from the underlying DBMS query results. Fetch  126  places the retrieved data into the user&#39;s address space. 
     Free  128  releases all resources associated with the specified Statement generated by Format  150 . 
     DBEnd  104  terminates the connection to the underlying DBMS made by DBInit  102 . 
     IAE Fetch  82  iteratively polls data from the IAE result data table generated after a select request. For each returned instance, the parameter OID specifies the OID of the associated instance. Fetch  84  is called by IAE Fetch  82  and fetches the results of a select request. 
     IAE TranCommit  56  commits (updates the IAE Database  20  for) all IAE database  20  updates done within the scope of the specified transaction. After a commit, the current transaction is available for further work. 
     IAE TranRollback  58  rolls back (does not update the IAE Database  20  for) all IAE database  20  updates done under the scope of the specified transaction. After a rollback, the current transaction is available for further work. 
     IAE TranEnd  54  terminates the specified IAE transaction. If any updates are outstanding, they are NOT committed. 
     IAE Destroy  86  deletes all resources associated with building an IAE Database  20  request. Free  88  is called by IAE Destroy  86  and releases resources associated with the specific database. 
     IAE DBEnd  44  disconnects the user from the IAE Database  20 . 
     Although the present invention has been described in detail, it should be understood that various changes, substitutions and alterations can be made thereto without departing from the spirit and scope of the present invention as defined by the appended claims.