Abstract:
Computer method and apparatus collapse program metamodels to provide a collapsed, in syntax view of the subject metamodel. The invention method and apparatus obtain multiple programming model packages. Each said package is formed of a respective plurality of model elements from the subject metamodel. Next the invention combines (e.g., collapses) the multiple programming model packages together to form a resultant collapsed package. The resultant collapsed package enables generation of an implementation of a desired software program and avoids the need for package links (representing package merge relationships between packages).

Description:
BACKGROUND OF THE INVENTION  
       [0001]     With the proliferation of software products and services, attempts have been made to codify and/or standardize the designing of software and software architecture. Examples include:  
         [0002]     The Booch Method and Modeling Language (see “Object Oriented Analysis and Design” by Grady Booch);  
         [0003]     James Rumbaugh and Associates&#39; Object Modeling Technique (OMT);  
         [0004]     the Object Oriented Software Engineering (OOSE) method by Ivar Jacobson; and  
         [0005]     the Unified Modeling Language (UML) which combines the foregoing and industry best practices.  
         [0006]     The UML is a visual modeling language (with formal syntax and semantics) for communicating a model or conceptionalization. Thus the modeling language specification specifies modeling elements, notation and usage guidelines and not order of activities, specification of artifacts, repository interface, storage, run-time behavior and so forth. In general, at the modeling level a “problem” is posed in terms of a customer&#39;s needs and requirements and may be referred to as the business problem system. The software designer develops a “solution” software product and or service that addresses the problem. The UML syntax enables software designers to express (specify and document) the subject problems and solutions in a standardized manner, while the UML semantics enable knowledge about the subject system to be captured and leveraged during the problem solving phase. See “UML in a Nutshell” by Simon Si Alhir, published by O&#39;Reilly &amp; Associates, September 1998. As such, the UML enables the sharing of information (including prior solution portions) and extension (without reimplementation) of core object oriented concepts (analysis and design) during the iterative problem-solving process for designing software products.  
         [0007]     The adopted UML 2.0 specification uses a so called “package merge” to define a number of different modeling languages and compliance levels. A “package” is a grouping of semantically related model elements and serves as a container for model elements that may be instantiated. A “relationship” is a connection between model elements that adds semantics to models. A “package merge” is a relationship between two packages where the contents of the target (merged) package are merged with the contents of the source (merging) package through specialization and redefinition. It is semantically equivalent to defining a subclass in the source package of every class in the target package. A package merge is indicated by a visibility relationship with a &lt;&lt;merge&gt;&gt; stereotype between two packages in a model.  
         [0008]     The Rose model for UML 2.0 Superstructure contains many package merge relationships. In a lot of cases, the specialization relationships have been explicitly included. In some cases, the corresponding redefinitions have also been explicitly defined. In most instances, however, this is not the case. Most redefinitions are implicitly defined through matching names as specified by the package merge semantics. Package merge does not introduce any new semantics into UML 2.0; it is only a convenience for specifying a set of generalizations and redefinitions. These generalizations and redefinitions can just as well be specified explicitly. In fact, UML 2.0 Infrastructure does not use package merge, but instead does the merge “by hand” and explicitly specifies all the generalizations and redefinitions.  
         [0009]     The Eclipse Modeling Framework (EMF) can be used to generate Java code from a Rose model, but encounters a number of issues when dealing with redefinitions. Even if the Rose model and/or the EMF code generator were modified to resolve these issues, the resulting implementation would still be unusable. The source of this problem is the way redefinition was used throughout the specification as a means of partitioning the model into levels of compliance. This may make sense at a conceptual level, but it complicates the target Application Program Interface (API) to a great extent.  
         [0010]     Although not introduced by package merge, these problems are exacerbated significantly by the shear number of package merges specified in the UML 2.0 Superstructure. Some of the issues, most resulting from redefinitions, are:  
         [0011]     Results in a huge class hierarchy with multiple packages having classes with the same name.  
         [0012]     Creates a very large number of uninteresting redefinitions (property redefinitions that do not change anything but the type, which cannot be handled by Java anyway).  
         [0013]     Creates a lot of instances of multiple inheritance of properties having the same name.  
         [0014]     A “downcast” model-to-model mapping from more general instances to more specific instances is required in order to use the existing general model instances in an extended API.  
         [0015]     A more specific class does not contain some of its redefined constraints because the property has to be implemented in its superclass.  
         [0016]     Client applications have to do a lot of downcasting because Java cannot implement UML 2.0 redefinition semantics; after the many levels of merges in UML 2.0, client developers will likely find it difficult to remember what has to be cast to what and when, leading to unexpected results.  
         [0017]     Merged constraints are lost for matching properties because, due to Java limitations, the superclass property is chosen when eliminating the property redefinitions.  
         [0018]     Using any of the inherited superclasses requires the client application to use a fully qualified class name.  
       SUMMARY OF THE INVENTION  
       [0019]     This invention provides a solution to the problems above.  
         [0020]     In a preferred embodiment, computer method and apparatus collapse program metamodels to provide a collapsed, in syntax view of the subject metamodels. The invention method and apparatus obtain multiple programming model packages. Each said package is formed of a respective plurality of model elements from the subject metamodel. Next the invention collapses the multiple programming model packages together to form a resultant collapsed package. The resultant collapsed package enables generation of an implementation of a desired software program and avoids the need for package links (representing package merge relationships between packages) of the prior art. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]     The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.  
         [0022]      FIG. 1  is a schematic view of one embodiment of the present invention.  
         [0023]      FIG. 2  is a schematic view of the preferred embodiment generating an implementation (target code).  
         [0024]      FIG. 3  is a schematic view of a computer environment in which the principles of the present invention may be implemented.  
         [0025]      FIG. 4  is a block diagram of the internal structure of a computer from the  FIG. 3  computer environment.  
         [0026]      FIG. 5  is a schematic illustration of computer systems implementing methods of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]     A description of preferred embodiments of the invention follows.  
         [0028]     By way of overview, the present invention defines a new package relationship that transforms the majority of the redefinitions in the UML 2.0 metamodel. This new relationship, &lt;&lt;collapse&gt;&gt;, results in a flattened API with one namespace in which there exists only one type with a given name. After having eliminated the majority of the redefinitions, the remaining ones may be dealt with in an appropriate way, given the limitations of the Java language.  FIG. 1  is illustrative.  
         [0029]     As shown in  FIG. 1 , given are a plurality of packages (P 1 , P 2 , P 3 , P 4 )  13   a, b . . . n,  each formed of a respective set of model elements  15  and package dependencies  17  (shown in dotted lines).  
         [0030]     In the UML 2.0 specification, UML is a root package. Package levels are:  
         [0031]     “kernel”—the core package level where concepts are introduced;  
         [0032]     “statemachines”—the level that specifies concepts related to states (such as “class”);  
         [0033]     “profiles”—the level where extensions of the modeling language are specified or profiled;  
         [0034]     “actions”—the level where atomic activities are defined; and  
         [0035]     “activities”—formed of plural actions, with subcategories of this level being basic, intermediate and completed.  
         [0036]     In other views of software modeling, the kernel package level may provide a definition, meaning and organization of a “class” concept, an “operation” concept and other concepts, while the statemachine level definition of “class” is more elaborated toward states. Thus there may be multiple different concepts of “class” (for example) depending on the package and package level.  
         [0037]     Referring to  FIG. 1 , for each of the various model elements  15 , there is a concept of “class”. Class may be defined one way for one package  13  (at for example a kernel or core package level) and a different way for another package  13  (at a same or different package level such as state machine states or activities/basic).  
         [0038]     The present invention collapses all of the packages  13  in UML 2.0 and produces a destination package  19  that effectively blends or otherwise combines all of the classes in the specification, using the most general types and the most general multiplicities. That is, destination package  19  is effectively the collapsed result of P 1  through P 4  (subject packages  13   a,  . . .  13   n ) and their respective package dependencies. In a preferred embodiment, destination package  19  is named ‘UML2’ and has the familiar structure and syntax of UML 2.0 so as to be sharable (usable) among all users. To that end, the present invention provides a transformation from packages  13  of various (ambiguous) namespace to a collapsed, in syntax view of subject metamodel.  
         [0039]     An implementation  21  is able to be generated from the resulting code generation model at  19  using, for example, EMF or the like. A complete XML schema can also be generated, which defines one namespace for all of the model elements it specifies. Although this schema deviates from that proposed by OMG in the adopted UML 2.0 specification, Applicants believe it is more useful because it ensures that all tools are using the same schema and that no data is lost during interchange, regardless of which subset of the types in UML 2.0 a given tool is using.  
         [0040]     In a preferred embodiment, the collapse transformation is defined by creating a new package  19  and adding visibility relationships with a stereotype of &lt;&lt;collapse&gt;&gt; between this new collapsing/merged result package  19  and all packages  13  which are to be collapsed. When the transformation is processed, all contents from the collapsed packages  13  and all of their subpackages are collapsed, recursively, into the collapsing package  19  based on the following rules. This avoids the need for the sets of links (for package merge relationships between packages) required in the prior art.  
         [0000]     Package Rules  
         [0041]     Packages match by name.  
         [0042]     Subpackages of the collapsed package  13  are recursively collapsed into the collapsing package  19 .  
         [0043]     For non-matching sub-packages, the collapsing sub-package is the collapsing package in the collapsing package  19 ; for matching sub-packages, the collapsing sub-package is the matching sub-package.  
         [0044]     Classifiers in the collapsed package  13  are collapsed into the collapsing package  19  according to classifier collapse rules.  
         [0045]     All other non-generalizable elements of the collapsed package  13  are copied into the collapsing package  19  with all references transformed to corresponding collapsed elements in the collapsing package  19 .  
         [0046]     If any contained collapse fails, the package collapse is not well-formed.  
         [0000]     Classifier (Class, Data Type, and Enumeration) Rules  
         [0047]     Classifiers match by name.  
         [0048]     For non-matching classifiers, the collapsing classifier is a newly created classifier in the collapsing package  19 ; for matching classifiers, the collapsing classifier is the matching classifier.  
         [0049]     Nested classifiers of the collapsed classifier are recursively collapsed into the collapsing classifier (but the UML 2.0 specification does not have nested classes).  
         [0050]     All features from the collapsed classifier are collapsed into the collapsing class according to their rules.  
         [0051]     If any contained feature collapse fails, the package collapse is not well-formed.  
         [0000]     Enumeration Rules  
         [0052]     Enumeration literals match by name.  
         [0053]     Matching enumeration literals are not changed; non-matching enumeration literals from the collapsed enumeration are added to the collapsing enumeration (by the non-generalizable element rule).  
         [0054]     If matching enumeration literals are not in the same sequence, the package collapse is not well-formed.  
         [0000]     Property Rules  
         [0055]     Properties match by name.  
         [0056]     For non-matching properties, the collapsing property is a newly created property in the collapsing classifier; for matching properties, the collapsing property is the matching property.  
         [0057]     A collapse of a matching property has the most general conforming type of the collapsed and collapsing properties; the property type is converted to the corresponding matching type in the collapsing package  19 , if any.  
         [0058]     A collapse of a matching property has the most general multiplicity of the collapsed and collapsing properties; a collapsing multiplicity has the least lower bound and greatest upper bound of all collapsed multiplicities.  
         [0000]     Association Rules  
         [0059]     Associations are binary.  
         [0060]     Associations match by name (including if they have no name) and their end association ends match by name.  
         [0061]     A collapse of a matching association is accomplished by collapsing the association classifier and its ownedEnd properties.  
         [0062]     If any matching ends cannot be collapsed, the package collapse is not well-formed.  
         [0000]     Operation Rules  
         [0063]     Operations match by name and parameter types, not including any return type.  
         [0064]     For non-matching operations the collapsing operation is a newly created operation with the same signature in the collapsing classifier; the collapsed operations are copied into the collapsing classifier.  
         [0065]     If an operation matches in all but the return type, the package collapse is not well-formed.  
         [0000]     Constraint Rules  
         [0066]     The constraints of the collapsed model elements  15  are added to the constraints of the collapsing model elements forming destination package  19  (by the non-generalizable element rule).  
         [0067]     As illustrated in  FIG. 2 , a subject user model formed of model elements  15  is initially represented by a Rose model  61  based on destination package  19 . A code generation model builder  63  records information about package collapse relationships when it processes the Rose model  61 . Later, during code generation, code generation model builder  63  processes collapse relationships between all packages  13  according to the rules outlined above. On output code generation model builder  63  provides the target implementation  21 .  
         [0068]      FIG. 3  illustrates an example computer environment in which the present invention operates. Client computer(s)  50  and server computer(s)  60  provide processing, storage, and input/output devices executing application programs and the like. Client computer(s)  50  can also be linked through communications network  70  to other computing devices, including other client computer(s)  50  and server computer(s)  60 . Communications network  70  can be part of the Internet, a worldwide collection of computers, networks, and gateways that currently use the TCP/IP suite of protocols to communicate with one another. The Internet provides a backbone of high-speed data communication lines between major nodes or host computers, consisting of thousands of commercial, government, educational, and other computer networks, that route data and messages. In another embodiment of the present invention, the methods are implemented on a stand-alone computer. In either network or standalone, the invention output software design and model implementations (API&#39;s) are sharable and reusable among users.  
         [0069]      FIG. 4  is a diagram of the internal structure of a computer (e.g., client computer(s)  50  or server computers  60 ) in the computer system of  FIG. 3 . Each computer contains system bus  79 , where a bus is a set of hardware lines used for data transfer among the components of a computer. Bus  79  is essentially a shared conduit that connects different elements of a computer system (e.g., processor, disk storage, memory, input/output ports, network ports, etc.) that enables the transfer of information between the elements. Attached to system bus  79  is I/O device interface  82  for connecting various input and output devices (e.g., displays, printers, speakers, etc.) to the computer. Network interface  86  allows the computer to connect to various other devices attached to a network (e.g., network  70  of  FIG. 3 ). Memory  90  provides volatile storage for computer software instructions used to implement an embodiment of the present invention (e.g., EMF/code generation model builder  63  and Rose models  61  of subject Program Routines  92  and Data  94 ). Disk storage  95  provides non-volatile storage for computer software instructions and data used to implement an embodiment of the present invention. Central processor unit  84  is also attached to system bus  79  and provides for the execution of computer instructions.  
         [0070]     Referring now to  FIG. 5  illustrated is another computer system  10  embodying the present invention techniques mentioned above. Generally, computer system  10  includes digital processor  12  in which subject modeling language and EMF code  20  are utilized. Input means  14  provides user commands, selections (generally communication) to computer system  10 .  
         [0071]     Responsive to input means  14  is user interface  22 . User interface  22  receives user input data from input means  14  and provides input data for processing and manipulation at  20 . The methods of the invention are implemented at  20  for collapsing metamodels and packages for use in the designing of Application Program Interfaces (subject implementations)  21  in Java, UML, EMF, object oriented programming languages and the like which are output at  16 . Output  16  may be a display monitor, printer or other computer.  
         [0072]     In one embodiment, computer program product  80 , including a computer readable medium (e.g., a removable storage medium such as one or more DVD-ROM&#39;s, CD-ROM&#39;s, diskettes, tapes, etc.) provides at least a portion of the software instructions at  20  and/or user interface  22 . Computer program product  80  can be installed by any suitable software installation procedure, as is well known in the art. In another embodiment, at least a portion of the software instructions may also be downloaded over a wireless connection. Computer program propagated signal product  83  embodied on a propagated signal on a propagation medium (e.g., a radio wave, an infrared wave, a laser wave, a sound wave, or an electrical wave propagated over a global network such as the Internet, or other network(s)) provides at least a portion of the software instructions at  20  and/or user interface  22 .  
         [0073]     In alternate embodiments, the propagated signal is an analog carrier wave or digital signal carried on the propagated medium. For example, the propagated signal may be a digitized signal propagated over a global network (e.g., the Internet), a telecommunications network, or other network. In one embodiment, the propagated signal is a signal that is transmitted over the propagation medium over a period of time, such as the instructions for a software application sent in packets over a network over a period of milliseconds, seconds, minutes, or longer. In another embodiment, the computer readable medium of computer program product  80  is a propagation medium that the computer system  10  may receive and read, such as by receiving the propagation medium and identifying a propagated signal embodied in the propagation medium, as described above for computer program propagated signal product  83 .  
         [0074]     Generally speaking, the term “carrier medium” or transient carrier encompasses the foregoing transient signals, propagated signals, propagated medium, storage medium and the like.  
         [0075]     While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.  
         [0076]     For example, the code generation model builder  63  may be implemented in UML, EMF and other modeling languages. The produced API or target code  21  may be in Java, UML, XML, EMF, object oriented programming languages and the like.