Abstract:
A method and system for defining a data mapping between at least two data structures is disclosed. The method of the present invention comprises selecting at least two data structures, wherein each data structure comprises a plurality of data elements and analyzing previous data mapping definition information to derive a definition of a data mapping between the data elements of the at least two data structures.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims benefit under 35 USC § 119 of United Kingdom Application No. 0229724.0, filed on Dec. 19, 2002. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates to the field of data transformations or mapping, and more specifically to the definition of such transformations.  
         BACKGROUND OF THE INVENTION  
         [0003]    Distributed systems typically comprise a multitude of heterogeneous applications all communicating using different languages. In order for two such different applications to communicate with one another, it is necessary that data in a format A from the first application is transformed into data in a format B understood by the second application. FIG. 1 a  shows a first example of the components that enable such a transformation to take place.  
           [0004]    Application  10 , by way of example, uses a SAP internal data format. In order to communicate with application  50 , a request from application  10  may go via a message broker/intermediary system  30 . Adapter  20  interfaces with Application  10  and transfers the SAP internal formatted message to broker  30 . At the broker it is determined that the message is destined for application  50  which uses an Ariba internal format. The broker therefore transforms the message received from application  10  into an Ariba internal message format suitable for transferring the message to application  50 . Upon receipt of this message, adapter  40  interfaces with application  50  and communicates the Ariba formatted message.  
           [0005]    It should however be appreciated from the above that the number of individual transformations required can be huge. A formula for determining the number of transformations is n*n-1, where n is the number of data types used (e.g. message sets, where a message set is the set of messages understood by one application), and we are defining transformations in both directions.  
           [0006]    For this reason an alternative solution was developed. Referring to FIG. 1 b , a “standard” format for communication is agreed upon by adapters  20  and  40 . One example of such a format is the Business Object Document (BOD) specification defined by the Open Applications Group. When application  10  wishes to communicate with application  50 , adapter  20  converts the data into BOD form which is received by adapter  40  and transformed into the Ariba data format. The number of transformations now is 2*n. Therefore for small numbers of applications there is no benefit, (e.g. 2 applications=4 transformations vs. 2 in the original design of FIG. 1 a ), but for larger numbers of applications the benefits are important (e.g. 5 applications=10 transformations vs. 20 in the original design of FIG. 1 a ). While FIGS. 1 a  and  1   b  show different integration topologies, this is not relevant to the transformation reduction. It is possible, for example, to achieve the same results by transforming to the “standard” format in the intermediary system.  
           [0007]    Nevertheless, it will be appreciated that a highly labour intensive activity when performing Enterprise Application Integration is the definition of data/message transformations. Each message set can be large and complex and typically consists of a number of different messages each containing a variety of different fields. For example, the OAG BOD standard version 7.1 has over 180 different messages. Ordinarily the user selects source and target messages and a tool presents them side by side. The user then defines the relationships between fields in the source message and fields in the target message.  
           [0008]    With reference to FIG. 2 it can be seen that message set A has a “part” message containing the fields “name”; “id”; “price”; and “description”. Message set B has a corresponding message and fields but uses different terms to refer to these. Thus a user has to identify that the “part” message in message set A corresponds to the “item” message in message set B. The user then has to map the fields within the “part” message to the fields within the “item” message. Thus “name” is mapped to “prodname”; and “ID” is mapped to “identifier” etc.  
           [0009]    This example is simple in that there is only one message in each set and there is a one to one correspondence between the fields. The reality is however typically far more complicated in that there may be numerous message sets; messages and fields to contend with and that there is not necessarily a one to one correspondence between the fields in two messages. Thus it is typically an onerous task to define the required transformations between messages in different message sets.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention is directed to a method and system for defining a data mapping between at least two data structures. The method of the present invention comprises selecting at least two data structures, wherein each data structure comprises a plurality of data elements and analyzing previous data mapping definition information to derive a definition of a data mapping between the data elements of the at least two data structures.  
           [0011]    Preferably the previous data mapping definition information comprises user defined information. Preferably the user is provided with a plurality of possible data mapping definitions. These can be prioritized to the user based on at least one predefined rule. Such prioritization makes the task of selecting a mapping from the plurality of possibilities easier. A variety of different rules for the prioritization process are preferably possible (e.g. a previous user selection).  
           [0012]    Preferably the two or more data structures are grouped into sets, a first data structure of the two or more data structures forming part of a first set and a second data structure of said two or more data structures forming part of a second set. Preferably previous data mapping definition information comprises at least one of:  
           [0013]    i) a previous data mapping definition between two data structures, one from the first set and one from the second set;  
           [0014]    ii) a previous data mapping definition between two data structures, one from the first or second set and the other from another set; and  
           [0015]    iii) a previous data mapping definition between two data structure which do not come from the first or second set.  
           [0016]    Such information is preferably used in the prioritization process. For example from a plurality of possible data mappings i) may be ranked more highly than ii) and ii) may be ranked more highly than iii).  
           [0017]    In the preferred embodiment the mapping definition information concerns messages of message sets. Preferably the information comprises at least one of:  
           [0018]    i) a message field to message field definition; and  
           [0019]    ii) a message name to message name definition.  
           [0020]    Preferably it is possible to use reverse mapping definition information for defining a data mapping. FIG. 4 provides an example of this where StaffNumber.TimeServed has previously been mapped to Employee.YrsServ. Thus this information is used, in the example, to map Employee.YrsServ to PersonnelNumber.TimeServed.  
           [0021]    The system may be implemented in the user&#39;s system or at an intermediary system such as a message broker. The invention is preferably implemented in software. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    A preferred embodiment of the present invention will now be described by way of example only and with reference to the following drawings:  
         [0023]    [0023]FIGS. 1 a  and  1   b  illustrate an overview of enterprise application integration (which includes message transformation) according to the prior art;  
         [0024]    [0024]FIG. 2 illustrates a defined correspondence between two message sets according to the prior art; and  
         [0025]    [0025]FIGS. 3 a ,  3   b ,  4  and  5  illustrate message transformation according to a preferred embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0026]    The present invention relates to a method and system for defining a data mapping between two or more data structures. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the preferred embodiment and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest scope consistent with the principles and features described herein.  
         [0027]    Throughout the specification, the terms transformation and mapping will be used interchangeably. In the preferred embodiment, the data structures can be treated as message sets. With reference to FIGS. 3 a  and  3   b , two message sets (MS) are selected by a user (A and B, step  100 ;  105 ). A source message and a target message are then selected by the user (step  110 ). (In this example the source message is Part and the target message is Item.) From message Part a field (Name) is chosen (step  120 ).  
         [0028]    It is determined whether there is any previous transformation definition information which might be of use here (step  130 ) and since there is not, the user defines this transformation, mapping the Name field to ProdName in the Item message of message set B (step  140 ). Information regarding this transformation is held in non-volatile storage for possible future use (step  140 ). (Note, there may not always be a corresponding field to map to in a target message—see below.) Following the same process, the user also defines Part.ID and Part.Price. As can be seen from FIG. 3 b , these are mapped to Item.Identifier and Item.Price (steps  160 ;  120 ;  130 ;  140 ). There is no corresponding field for Part.Description in the Item message and so the transformation for this field is not defined.  
         [0029]    Having defined transformations for all the fields in the Part message for which there are corresponding fields in the Item message, it is determined at step  170  that there is another source message (Order) in set A and a target message in set B between which transformations are to be defined (step  110 ). Field ID is selected from this message (step  120 ). Part.ID was previously defined as mapping to Item.Identifer, thus it is deduced that any field named ID in message set A is likely to map to any field named Identifier in message set B (step  130 ).  
         [0030]    In message set B a PurchaseOrder message exists and this message includes the field Identifier. Thus a suggestion is made to the user that Order.ID might map to PurchaseOrder.Identifer. The user chooses to accept PurchaseOrder.Identifier as the correct definition of Order.ID and thus this recommendation is executed and information regarding this choice is added to non-volatile memory (step  155 ;  165 ).  
         [0031]    The next field in message Order is Quantity (steps  160 ;  120 ). Quantity is not a field that has been seen before and so the user defines its correspondence to PurchaseOrder.Quantity and information regarding this is added to non-volatile memory (steps  130 ,  140 ). However with Order.Price, the system has previously seen that Part.Price maps to Item.Price and therefore suggests that Order.Price might map to PurchaseOrder.Price (steps  160 ;  120 ;  130 ;  150 ). The user then chooses to accept this recommendation and it is executed and information regarding this choice added to non-volatile memory (step  155 ,  165 ).  
         [0032]    The process continues with StockCheck.ID (steps  160 ;  170 ;  110 ;  120 ). Previously Part.ID was mapped to Item.Identifer; and Order.ID was mapped to PurchaseOrder.Identifer. The system thus deduces that StockCheck.ID might well map to StockLevel.Identifier (steps  130 ;  150 ). In this example, the user chooses to accept the recommendation and this is executed and information regarding this action is stored in non-volatile memory (steps  155 ,  165 ). Finally StockCheck.Quantity possibly maps to StockLevel.Quantity based on the previous transformation of Order.Quantity to PurchaseOrder.Quantity (steps  160 ;  120 ;  130 ;  150 ). Again this is accepted and executed (step  155 ,  165 ).  
         [0033]    Because there are now no more messages in set A (step  170 ), it is determined whether there are any more message sets for which transformation are to be defined (step  180 ). Note this may mean defining a transformation between a current message set and a new message set or between two completely new message sets. If there are any more message sets, then the process returns to step  105  and starts over again. Otherwise, the process ends at step  190 .  
         [0034]    The preferred embodiment of the present invention can aid the user in a number of different ways. Prioritization of recommendations is discussed in more detail later; however it will be briefly discussed here. For example, if the user has defined Order.ID as mapping to PurchaseOrder.Identifier, thus it is known to the system that there is a correspondence between the Order message in set A and the PurchaseOrder message in set B. It can use this information to prioritize suggestions about possible future transformation definitions (e.g. Order in message set A might map to PurchaseOrder in previously unseen message set C).  
         [0035]    Further, the storage of information at step  165  can be used to prioritize suggestions. For example, the previous definition information used to make the current recommendation may have come from a transformation between two different messages sets (see below), if the user selects that recommendation for messages sets A and B this information can be stored to prioritize this recommendation for other transformation definitions relating to the same two message sets (A &amp; B).  
         [0036]    It will now be appreciated by one skilled in the art that the flow described above relates to just one way in which the invention could be implemented. For example, in an alternative embodiment, the tool first analyses all the messages in two message sets and makes a series of recommendations. The user can then address recommendations for each field in turn, choosing to accept or reject these. Any fields for which there are no recommendations, or for which the user does not like the suggested recommendations, are left to the user to define.  
         [0037]    It will no doubt also now be appreciated by one skilled in the art that transformations for all messages in a message set may not be required. Further, a one to one mapping has been shown here. In practice n messages may be mapped to m messages (for example three messages may map to two messages.)  
         [0038]    The suggestions for possible transformation definitions do not have to come from the same message set. FIG. 4 shows message sets C, D, E, F and G. Sets C and D relate to personnel records and the correspondence between messages (one shown) in the two sets have been defined prior to defining mappings for message sets E and F. Message sets E and F relate to catering records. The fact that Name in the employee message of set C is defined as mapping to FullName in the PersonnelNumber message of set D is used to suggest to the user that Employee.Name in message set E may map to PersonnelNumber.FullName in message set F. Further if the transformations between messages in set C and D are being defined, information from previous transformation definitions involving another set and C or D can be used.  
         [0039]    In the example, StaffNumber.TimeServed (message set G) has been mapped to Employee.YrsServ (message set C). This information can be used to suggest that Employee.YrsServ may map to PersonnelNumber.TimeServed in message set D. (This assumes that the previously defined mapping works in reverse.)  
         [0040]    Correspondence between message names as well as message fields may also be used. For example, the fact that the user has defined a link between the Employee message in set C and the PersonnelNumber message in set D may be used to suggest a link between the Employee message in set E and the PersonnelNumber message in set F. Such information is useful in prioritising suggestions to the user regarding field definitions.  
         [0041]    When defining transformations between two message sets C and D, suggestions could be prioritised to the user based on some predefined rules. For example the priorities could be as follows:  
         [0042]    1. Information from existing C and D message set transformation definitions has top priority.  
         [0043]    2. Information from transformation definitions including one of message set C or D is prioritised next (e.g. C and G)  
         [0044]    3. Information from any other transformation definition is prioritised last (e.g. E and F).  
         [0045]    A tool implementing the invention is preferably implemented in computer software. This tool could be provided with the message broker/intermediary system, or adapter software (e.g. as shown in FIGS. 1 a  and  1   b . The components of such a tool according to a preferred embodiment are shown in FIG. 5.  
         [0046]    The tool  200  comprises a selection component  210 . Using this component, the user can select two message sets between which to define transformations. Having made this selection, an analyser  220  component is invoked which scans messages in the selected message sets.  
         [0047]    For each message and field, within the message sets, the analyzer determines whether it knows of previous transformation information which might be useful with regard to the defining each message and field transformation. In order to do this, analyzer component  220  consults previous transformation definition information held in non-volatile storage  230 . If it finds helpful information within storage  230 , it uses such information to suggest possible definitions to the user via suggestion component  240 .  
         [0048]    The user can then use selection component  210  to choose one of the suggested definitions.  
         [0049]    If on the other hand no such useful information is held within storage  230 , user definitions component  250  enables the user to define the correspondence between a message/field in the source message set and a message/field in the selected destination message set. This definition is then stored in storage  230  for possible future use.  
         [0050]    Through aspects of the preferred embodiment of the present invention, mapping definitions from previous defining sessions are stored for future sessions. In this way the previously onerous task of defining transformation information is alleviated.  
         [0051]    The present invention has been described in accordance with the embodiment shown, and one of ordinary skill in the art will readily recognize that there could be variations to the embodiments. For example, while the invention has been defined in terms of messages and messaging systems, the invention is not limited to such and is applicable to any environment where data of one format needs to be converted to data of another format. Accordingly, many modifications may be made by one of ordinary skill in the art without departing from the spirit and scope of the appended claims.