Software Engineering II

1
Software Engineering II

Metamodeling
di
Simon Lepore
22/05/2002
2
Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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Terminology

• Model A semantically closed abstraction of a
  system
• Meta-model A semantic information model
• Meta-metamodel The language in which to express
  
• meta-models

• Metamodeling Is an activity, and this
  activity produces
• meta-models

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Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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Scope

• An attempt at describing the world around us for
• a particular purpose

• As a schema for data that needs to be exchanged
  or
• that needs to be stored
• As a language that supports a particular
  methodology or process(the original purpose of
  the UML meta-model)
• As a language to make information on the web
• more semantic

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Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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What is Metamodeling

• To express kinds of things in order to model them
  
• in a particular system
• To define our concepts in terms of other concepts
• It expresses various models that it wants to
  define
• (the RELATIONSHIP are instances of E-R
  diagram)
• Then model dictate the way in which the next
  level
• would be expressed

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What is Metamodeling

• Some traditional types of users for meta-models
• CASE tool vendor / modeling tool vendor
• In essence, what the chief architect does is
  extending the meta-model.The data structures in
  the tool are
• the physical representation of the meta-model.
• Repository vendor
• For example, you may sell a repository (or
  database, or directory, ...) to customers who
  want to store
• software/systems development information in it.
  They may call it "meta-data".
• Systems integrator
• One the first activities in such a project is to
  understand the meaning of the data in all the
• systems that need to be integrated which data
  has the same meaning, which data is
• complementary, and how everything relates.
  Performing this analysis yields a semantic
• model for the types of data to be integrated, in
  other words, a meta-model.
• End user
• Functionality is one aspect ("this one has a nice
  shiny button over here"), but the supported
  meta-model
• is even more important. After all, the meta-model
  determines what you can express with the software
  

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Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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Metamodeling
meta-metamodel level
Obj.Type

metamodel level
ProcessType
Attribute Type
EntityType
model level

Product
Employee

data process level
Bob
Betty
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Metamodeling

• A metamodel is a model of models.
• It contains meta-obj. type.
• Object types whose istances are also object
  types.

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Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Maintaining modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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Levels

• Each level is supposed to define the basis for
• instantiating the next
• The number of the levels adapted depends on
• the points of view.
• OMG organized hierarchies in four levels
• meta-meta-model level description of the
  structure and
• semantics of meta-meta-data
• meta-model level the descriptions (i.e.,
  meta-meta-data) that define the structure and
  semantics of meta-data
• model level meta-data that describes
  information
• user level the information that we wish to
  describe

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Levels
Obj.Type

Process Type
meta-model level
Attribute Type
Entity Type

model level
Person
Inventory clerk s view
Product

data process level
model level
BOTurnt
SonyCDp
Salepersons view
data process level
V45728
?
V45729
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Levels

• Metamodeling can define many levels of types
  whose
• instances are also types
• Two various needs of approach salespersons
• object is the clerks object type

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Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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Modeling levels

• For change the kinds of object types that can be
  defined
• at the model level, a metamodel must be
  modified.
• These rigid structures are implemented in the
  most
• CASEtool this is a problem

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Modeling levels

• Most CASE tools maintain models and metamodels
• as physically separate levels.

Metamodel
Model
defines Instances of
Data and process
defines Instances of
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Modeling levels

• Problem solution

Model level
Metamodel level
Object
Object type
Model level
Metamodel level
Object type is now an Object and Object is an
Object type
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Modeling levels

• This cannot be supported by most CASE tools.
• Secondly, modifying separately maintained
  metamodels
• is often impossible.
• No metamodel customization features from sw
  vendors
• or may consider the contents of its metamodel
  to be
• proprietary.
• Exist implicity as program code(difficult to
  modify).

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Modeling levels

• Level modeling falters when the bottom level also
• instances(such as exsample)and so on
• The ability to instantiate at the model level
  were
• allowed, any number of levels, could be
  defined within it
• This ability could be supported by defining
  Object
• is an instance of one or more Object types.

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Modeling levels
Object Type

• Each Object type classifies
• any number of Objects.
• Each Object instance is
• an instance of one or more
• Object type.

classifies
Is an instance of
Object
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Modeling levels

• In other worlds, by defining the is an instanced
  of
• mapping at the metamodel level, all levels
  can have
• types and instances.
• Only difference between the model and the
  metamodel
• levels is that one has instances of the
  other.

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Modeling levels
Obj.Type

Process Type
Is an instances of
Attribute Type
Entity Type

Is an instances of
Person
Product

Is an instances of
BOTurnt
SonyCDp
V45728
Is an instances of
V45729
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Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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Modeling in one framework

• Modeling in rigid, physically separate levels can
  create
• problems.
• These can remedied by modeling within a single
  frame-
• work instead.

• Model maintenance is performed on one coherent
• and integrated model, not fragmented by
  levels.
• Object type and instances share the same
• model.
• Any numbers of instantiates levels is possible.
• since a rigid number of levels is not
  required.

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Modeling in one framework

• A single framework model can be used to decribe
  it self
• If a model is sufficently descriptive, it should
  be able to
• specify its own object types.
• A small subset of the model can then describe a
  much
• larger subset and so on.
• If a model can be a metamodel to describe itself,
  it can
• be a metamodel to describe other models.

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Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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Kernel Metamodel

• An approach of this kind can both describe
  different
• models and provide a common framework for
  expressing
• and comparing models.

Kerenel metamodel
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Kernel Metamodel

• The kernel metamoddel with which the model
  describes
• itdelf would contain such primitive obj
  types as Object
• Type, Object, Relation and Function.
• Also contain Operation, Trigger Rule, Control-
• Condition for support processing
  requirements.
• These primitives, can be used to form
  foundational
• construct for other structures.

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Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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In last

• In a single framework model, the boundaries are
  non-
• existent.
• The only reason for inhibiting changes to the
  kernel meta-
• level is to maintain standardization.
• The standards for the future are most important
  for the
• interoperability

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Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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MOF(Meta Object Facility)

• It is a Standard of Object Management Group(OMG).
• In September of 1997, finalized a standard.
• MOF is the M3 levels (meta-meta-model)
• Is Object Oriented.

Meta-meta-model
M3
Meta-model
M2
Model
M1
Object
M0
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Four levels(OMG)

• M0 it represents the data busines level
• (client n 1234.)used from DBMS, SO.
• M1(model) describes the structure of M0 level
• (identifier client1234)1234 is an instances
  of M1 level.
• M2(metamodel) describes the structures of M1
  level
• (atributeidentifier client) identifier
  client is an
• instances of M2.
• M3(meta-metamodel)its a model to decribe another
• model and the structures of m2
  level(i.e.meta-atr atribute).

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OMG levels
M3
Specify meta-meta classes for metamodel.
Specify meta classes for metamodel. i.e. Class
M2
UML Package notation
M1
Specify classes for UML model of designer.
ltltinstanceOfgtgt
Object
M0
Secify a pure Object
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OMG levels
MOF Meta-metamodel
MetaOperation
Meta-Classes
Meta-Attributes
ltltusegtgt
ltltinstanceOfgtgt
ltltinstanceOfgtgt
UML metamodel
Atributes
Operation
Classes
ltltinstanceOfgtgt
ltltinstanceOfgtgt
ltltusegtgt
Girl
Name String
Analisys model UML
Age Integer
GetName() String
GetAge() Integer
ltltinstanceOfgtgt
ltltusegtgt
Maria Girl
Object
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Goal of MOF

• M3 describe itself (MOF Model is formally defined
  using its own meta-modeling constructs).
• UML is an instancies of MOF.
• Defines a set of CORBA IDL interfaces that can be
  used to define and manipulate metamodels and
  their models
• provides the infrastructure for implementing
  CORBA-based design and reuse repositories
• specifies precise mapping rules to automatically
  generate CORBA interfaces for metamodels,thus
  encouraging consistency in manipulating metadata
  in all phases of the distributed application
  development cycle

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Goal of MOF

• Interoperability, interchange of meta data in
• distribuited systems, distribuited object
  systems.
• Beyond to the repository MOF-based we can use(for
  inter-
• change meta-data)the format
  stream-based(standard XMI).
• XMI defines the rules for mapping from MOF to XML
  to generate automatic XML code.
• Essentially a subset of the UML core
• Class
• attributes
• operations (only name and functionality, no
  associated method)
• Generalization
• sub-Class inherits all features of its
  super-Classes
• any explicit Constraints that apply to a
  super-Class and
• any implicit behavior for the super-Class apply
  equally to the sub-Class
• At the M1 level, an instance of an M2-level Class
  is type substitutable for instances of its
  M2-level super-Classes
• Abstract classes
• Root and leaf classes

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Goal of MOF

• Association
• Association links
• Multiplicity specification
• Navigability setting
• Aggregationasymmetrical association Component
  is part of at most one composite
• A component cannot be part of itself (also
  indirectly)
• When a composite is deleted, all its components
  are deleted
• References(attributes corresponding to navigable
  associations ends to offer a simple way to update
  links)
• DatatypesMeta-model definitions often need to
  use attribute and operation parameter values that
  have ordinary types
• Packages
• Groups elements into a meta-model
• Mechanisms to compose packages
• Constraints
• Used to attach consistency rules to other
  meta-model components
• A Constraint comprises constraint name, a
  language used to express the consistency rules

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Description of Mof

• Can be described by using the MOF model itself
• circularity problem
• Direct description by natural language and UML
  diagrams
• Abstract and Concrete Mappings

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Description of Mof

• The Abstract mapping (defined inThe MOF Abstract
  Mapping chapter)
• fleshes out a MOF meta-model into an abstract
  information model (i.e., by spelling
• out the logical structure of the meta-data
  described by the meta-model).
• The IDL Mapping (Section 2.4.2, CORBA Meta-data
  Services - The MOF
• IDL Mapping, on page 2-22) produces the standard
  OMG IDL and associated
• behavioral semantics for meta-objects that can
  represent meta-data conforming to
• the meta-model.
• The XML Mapping (see Section 2.4.3, Meta-data
  Interchange - The MOF
• XML Mapping, on page 2-22) produces the standard
  XML DTD for interchanging
• metadata conforming to the meta-model.

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Index

• Index
• Terminology
• Scope
• What is Metamodeling
• - Metamodeling
• - Level architectures
• - Modeling levels
• - Modeling in one framework
• - Kernel metamodel
• - In last
• Mof
• Case Study

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Case study

• Introduction
• Feasibility Study
• W2000 as a profilable MOF Meta-model
• Technological solution
• A p-meta-model for W2000
• An example W2000 model
• Conclusions and future work

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Introduction

• Web-based hypermedia systems are becoming more
  and
• more sophisticated, new modeling requirements
  constantly
• arise, and design models must constantly
  evolve.(an example of this
• evolutions is HDM Hyper text design model)
• Since design tools should complement models to
  support an
• efficient design process, model evolution raises
  technological
• issue Design tools must be modified when their
  underlying
• model changes. This is why the paper proposes a
  general
• approach to efficiently update design tools in
  response
• to model evolutions.

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Introduction

• The key ideas are
• the description of a hypermedia model
• in terms of a general meta-model, powerful
  enough to
• express the semantics of current and future
  design constructs.
• the transformation of a hypermedia design tool
  into a meta-CASE tool, able to cope with model
  updates without requiring to be redefined and
  rebuil from scratch.

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Introduction

• The approach is presented by discussing a case
  study, that is,
• the feasibility study to transform the design
  toolkit, Jweb, into
• a meta-CASE tool (Jweb3).
• This tool will support the latest version of our
  model (called
• W2000), and will easily evolve with the model it
  supports.
• In this document it comes discussed the adoption
  of the OMG
• metamodeling standards MOF and XMI as enabling
  technology
• a sample of the representation of W2000 in terms
  of MOF, and
• the sketch of the architecture of the
  under-implementation
• Jweb3.

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Case study

• Introduction
• Feasibility Study
• W2000 as a profilable MOF Meta-model
• Technological solution
• A p-meta-model for W2000
• An example W2000 model
• Conclusions and future work

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Feasibility Study

• As to the first aspect, they decided to probe the
  possibilities of
• using existing UML CASE tools as temporary
  front-ends for
• the forthcoming schema editor.
• The idea was not to select the best available
  tool, but simply
• do some experiments and delay the implementation
  of a special
• purpose editor to better refine W2000 constructs.
  As side effect,
• this implied that they did not want to work with
  proprietary
• formats to store models(W2000 schemas), but they
  needed a
• cross -platform standard to be able to change the
  front-end
• according to our needs.
• They decided to exploit the OMG novel
• way to meta-modeling to find a cumulative
  solution.

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Feasibility Study

• Using the OMG jargon, they can say that each
  model (i.e.artifact)
• must be compliant to a given meta-model (i.e.,
  notation).
• This definition allows their to decompose a CASE
  tool into a
• provider of modeling features, which depends on
  the supported
• meta-model, and a consistency checker between
  defined models
• and their meta-model. Meta-CASE tools do a
  similar job at a
• meta-meta-level. Meta-CASE tools let the
  developer define his
• own meta-model and express the semantics of the
  primitives of
• this meta-model in terms of a meta-metamodel.

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Feasibility Study

• Describing a new modeling feature of a meta-model
  (e.g., a new
• primitive for W2000) with a meta CASE tool would
  require the
• designer to describe the semantics of the new
  construct in terms
• of the meta-meta-model.
• The key point is that a meta-metamodel
• (MOF) supplies all modeling features to render
  extensions and
• mechanisms to (automatically) update the tools
  with respect to
• consistency checking and manipulation operations.

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Case study

• Introduction
• Feasibility Study
• W2000 as a profilable MOF Meta-model
• Technological solution
• A p-meta-model for W2000
• An example W2000 model
• Conclusions and future work

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W2000 as a Profilable MOF Meta-model

• W2000 can be seen as a UML extension (profile,
  according to
• the UML terminology).UML, in fact, supplies
  ad-hoc features
• (stereotypes, tagged values, and constraints) to
  extend the
• Original UML to cope with particular needs and
  specific
• application domains.
• Defining W2000 as a UML profile allows us to
  exploit
• UML commercial tools, but also XMI-UML, that is,
  the UML
• instantiation of XMI , which is rapidly becoming
  the lingua
• franca to exchange UML models in a
  vendor-independent way.

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W2000 as a Profilable MOF Meta-model

• The adoption of UML profiles is enough to use UML
  CASE
• tools as front-ends for the schema editor, but
  does not allow
• semantic checks. Currently, available CASE tools
  support
• profiles partially(only Objecteering provides
  some support)
• Evolution and consistency checks would not be
  possible. This is
• why they decided to adopt MOF to describe the
  W2000 meta-
• model, that is,to give a precise definition of
  W2000 concepts in
• terms of a flexible meta-metamodel.

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W2000 as a Profilable MOF Meta-model

• The W2000 meta-model reuses many UML concepts,
  and this
• means that we can see W2000 as a UML profile and
  all possible
• versions of W2000 constructs can always be mapped
  onto
• instances of UML primitives, but with respect to
  conventional
• UML profiles it satisfies also an additional
  condition
• All concepts (both new and borrowed ones) are
  defined using
• MOF. Thus, they can say that W2000 is a
  profilable MOF meta
• -model (hereafter, p-meta-model). The reason for
  introducing
• the concept of p-meta-model is that if the UML
  metamodel can
• be described in terms of MOF, the opposite does
  not hold true,
• not all meta-models described in MOF can be
  mapped onto
• the UML meta-model.

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Case study

• Introduction
• Feasibility Study
• W2000 as a profilable MOF Meta-model
• Technological solution
• Remarks
• A p-meta-model for W2000
• An example W2000 model
• Conclusions and future work

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Technological solution

• The gray box in the upper left corner identifies
  meta-modeling technology
• all other tools belong to the usual modeling
  chain, which must be enabled by
• a set of preliminary meta-modeling steps. They
  start by defining the W2000
• p-meta-model
• 
  
• Usually they do this using Rational Rose
  integrated with the Unisys add-on
• for XMI. This model, stored in XMI-MOF, is the
  main input to the two meta-
• modeling tools.

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Technological solution

• The translator generator produces a translator
  from XMI-UML to XMI-
• W2000 as a set of XSLT rules.
• The checker generator uses the same meta-model to
  produce a set of
• Schematron rules.
• The designer specifies his W2000 models using his
  preferred UML editor
• and stores them in XMI-UML. The translator,
  through the XSLT rules,
• transform the XML file compliant to XMI-UML to
  another XML file, but
• compliant to XMI-W2000. This file is then the
  input to the checker that
• validates it through the Schematron rules.

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Remarks

• Even if p-meta-models have been defined to solve
  a specific problem,
• that is, to define the meta-model of W2000, they
  are absolutely general
• and can be used in all those cases where either
  we need (want) a MOF
• definition of an extended UML notation or simply
  we want to integrate
• MOF-based and UML-based tools.
• They implemented all logical components of Figure
  through special-
• purpose scripts and XSLT sheets, all coordinated
  by HTML interfaces.
• This implementation style should better fit
  evolution and simplify
• maintenance.

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Case study

• Introduction
• Feasibility Study
• W2000 as a profilable MOF Meta-model
• Technological solution
• A p-meta-model for W2000
• An example W2000 model
• Conclusions and future work

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A p-meta-model for W2000

• This section presents an example application of
  the p-meta-model of
• W2000 . The p-meta-model for W2000 (Figure 2)
  comprises the three
• standard UML packages, and the new W2000 package.
• 
  Foundation package supplies all basic
  
• 
  modeling elements(classes,attributes,
• 
  associations, etc.)
• 
  BehavioralElements package supplies
  the
• 
  elements to specify the dynamic
  behavior
• of a model. ModelManagement package supplies the
  means to cope with
• complexity and organize a model into submodels
  according to the different
• viewpoints. The new package, W2000, defines how
  we extended UML to
• represent W2000 constructs.

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A p-meta-model for W2000

• The profilability of the p-meta-model implies
  that all new W2000 concepts
• be specified as extensions to standard UML
  elements, that is, W2000
• elements are subclasses of standard UML
  meta-model classes.
• This organization is partially shown in
  Figure,which collects some excerpts
• from the W2000 package
• Information Model Design(fig. a) classes Entity
  and Component are both
• subclasses of class Class (defined in the Core
  subpackage of the UML
• Foundation package). Both classes are abstract
  classes because Entity are
• always specialized in either EntityTypes or
  SpearEntities, while
• Components become ComponentTypes or
  SpearComponents. Types are
• similar to classes They will be instantiated as
  many times as needed in the running
• application spear elements correspond to
  singletons They specify special-purpose
• elements singularly instantiated in the
  application.

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A p-meta-model for W2000

• Access Layer Design(fig. b) has a similar
  organization. A Collection,
• abstract concept, comes from a Class and is
  specialized in SpearCollections
• and CollectionTypes. Moreover, each collection
  has a
• CollectionCenterType,which is a subclass of
  Center-Type.
• Navigation Design(fig. c)
• Once more, Nodes must be either NodeTypes or
  SpearNodes. Links must be
• either CollectionLinks or SemanticLinks, or
  StructuralLinks.
• Collection links relate the elements of a
  collection with their center, semantic links
• correspond to semantic associations, and
  structural links render the component-based
• decomposition of complex entities.

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A p-meta-model for W2000
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Case study

• Introduction
• Feasibility Study
• W2000 as a profilable MOF Meta-model
• Technological solution
• A p-meta-model for W2000
• An example W2000 model
• Impact on Jweb
• Conclusions and future work

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An example W2000 model

• Figure presents the information model for the
  paper entity type. The entity
• is structured in three main components The
  abstract is always part of the
• paper and it presents some basic information,
  like the paper title, authors,
• and affiliation, along with other information
  required by the conference, that
• is, paper id (number) and review status.

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An xample W2000 model

• Either we have a first submission, or after
  accepting the paper, we have
• its camera-ready version.
• These components reuse also some information
  already defined in the abstract.
• Each time an attribute (slot) is reused in a
  component, we simply refer to its original
• definition, instead of re-specifying it.
• This way, we avoid inconsistent redefinitions
  and we maximize reuse.

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An xample W2000 model

• When we move to navigation design, Figure 6(a),
  we see that the paper has
• been decomposed in three nodes. Once more, the
  main one contains all base
• information, while the other two nodes correspond
  to the first submission
• and camera-ready respectively. The actual
  contents of these nodes is
• specified using the keyword body, which make
  readers refer to the
• information design to understand the actual
  contents.

a)
b)
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An xample W2000 model

• For example, the contents of the AbstractNode
  node is defined by the
• body of the Abstract component. The
  correspondence between nodes
• and components is not mandatory, but it helps
  modularize the design.
• Users are free to specify the contents of nodes
  as lists of attributes taken
• from the entities and components that they
  embody.
• Figure 6(b) shows how the user of the Web
  application can navigate among
• papers and authors.

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Impact on Jweb

• A briefly introduce on toolset for clarify its
  main components.
• Jweb assists designers during the whole design
  process from information
• design to prototype and enactment. Figure shows
  its main logical
• components
• The editor lets designers design their
  applications using HDM/W2000 and produces a
  HDM/W2000 schema.
• The mapper takes this schema and automatically
  generates the relational
• schema for the editorial repository, suitable
  interfaces for populating the repository,
• and a general description (XML mapping) of the
  relational schema.

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Impact on Jweb

• The configurator reads the HDM
• schema, the description of the editorial
  repository, and the editorial contents and
• allows for the creation of special-purpose
  filters to select data the description of
• these filters is rendered in XML.
• The generator uses the HDM/W2000 schema, the
  description of the editorial
• repository and its contents, together with the
  filters defined to select data, and
• generates the run-time database, populating it
  with the editorial contents suitably
• filtered.
• The engine reads the contents from the run-time
  database, presents this contents
• to user and is responsible formanaging the
  interaction between the user and the
• application.

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Case study

• Introduction
• Feasibility Study
• W2000 as a profilable MOF Meta-model
• Technological solution
• A p-meta-model for W2000
• An example W2000 model
• Conclusions and future work

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Conclusions and Future Work

• The group experiments in using the meta-modeling
  technology to support
• design tools are so far limited to the editor,
  but starting from the p-meta-
• model they induced a non-trivial modification and
  they studied the impact of
• these modifications.
• The main bottleneck was the definition and test
  of all (new) constraints in
• Schematron, but all other changes were almost
  trivial and they could be
• obtained automatically.

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Conclusions and Future Work

• This exercise suggested two interesting
  considerations
• The availability of a real MOF repository
  together with a friendlier notation
• for specifying constraints would further
  shorten the maintenance process.
• If we had done the same exercise using our
  standard way, we would have
• used the following process
• 1. The new meta-model would have been coded
  directly using a DTD, with
• suitable comments to explain the meaning of
  the new/changed features
• 2. The implementer in charge of working on the
  new editor (component)
• would have taken this definition as the
  reference for his work.

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Software Engineering II

• The End

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References

• www.metamodel.com
• Site for to learn much about model metamodel end
  modeling
• Theres many definition about models
• www.omg.org
• Object Managment Group, leader of O-Otechniques
• Unified Modeling Language Specification version
  1.4, Beta 1, November 2000.
• Meta Object Facility Specification version 1.3
  New Edition March 2000.
• www.jamesodell.com
• Is a consultant, writer, and educator in the
  areas of object-oriented and agent-based systems,
  business reengineering, and complex adaptive
  systems.
• Meta-modelling 1995
• saturne.info.uqam.ca/Labo_Recherche/Larc/Metamode
  lingWorkshop/Odell/metamodeling/metamodeling.ps
• baresigarzottomainettipaolini_at_elet.polimi.it
• Meta-modeling Techniques Meet Web Application
  Design Tools, L. Baresi, F.
• Garzotto, L. Mainetti, and P. Paolini
  Dipartimento di Elettronica e Informazione
• Politecnico di Milano www.elet.polimi.it

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Schematron

• Schematron is a structural schema language that
  differs from other schema
• languages since it not based on grammars but on
  finding tree patterns in
• the parsed document. This approach allows for the
  definition of simple
• and powerful validation engines.
• Schematron can be used to find specific patterns
  in an XML document in
• this case it is used to validate W2000 models
  against the constraints
• identified in the metamodel.

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Schematron Rules

• ltpattern name"SemanticAssociation"gt
• ltrule context"
• //W2000.SemanticAssociation
• /Foundation.Core.Association.connection
• /Foundation.Core.AssociationEnd
• /Foundation.Core.AssociationEnd.type/
• //W2000.SemanticAssociationCenterType
• /Foundation.Core.Association.connection
• /Foundation.Core.AssociationEnd
• /Foundation.Core.AssociationEnd.type/
• "gt
• ltassert test"
• (local-name(id(_at_xmi.idref))
• W2000.EntityType) or
• (local-name(id(_at_xmi.idref))

W2000.SemanticAssociationCenterType)
or (local-name(id(_at_xmi.idref)) W2000.CollectionT
ype) or (local-name(id(_at_xmi.idref)) W2000.Compo
nentType) "gtA SemanticAssociation link only
EntityTypes, ComponentType, SemanticAssociationCen
terType, and CollectionTypelt/assertgt lt/rulegt
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Logical architecture of Jweb

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Hypertext Design Model

• Since its first definition in 1991, HDM has
  originated a family of
• variants (HDM2, HDMlite) and, more recently,
  W2000.
• W2000 has been defined in response to the
  transformation
• ofWeb-based hypermedia from read-only
  navigational
• repositories to complex applications that
  combine navigation
• and operations in a sophisticated way.
• W2000 enriches the latest version of HDM with
  concepts and
• notations for modeling richer information
  structures as well as
• operations and services accessible through the
  Web.
• It exploits the Unified Modeling Language UML and
  its
• customizability to ascribe W2000 with a standard
  graphical
• syntax.

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