EclipseCon 2007: Effective Use of the Eclipse Modeling Framework
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The document provides an overview of the Eclipse Modeling Framework (EMF), including what EMF is, its components, code generation capabilities, and typical usage scenarios. EMF allows modeling domain concepts using Ecore models and generates Java code for the models. It provides runtime support for creating and manipulating model instances programmatically and through graphical editors.
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EclipseCon 2007: Effective Use of the Eclipse Modeling Framework
- 1. Christian W. Damus, Kenn Hussey, Ed Merks and Dave Steinberg IBM Rational Software Ottawa and Toronto, Canada EMF, EMFT, and MDT Projects Effective Use of the Eclipse Modeling Framework https://w3-03.ibm.com/legal/ipl/iplsite.nsf/pages/wtts-trademarks+home
- 2. Part 1: Introduction to the Eclipse Modeling Framework
- 21. EMF Architecture EMF Runtime EMF Tools Core Edit Codegen Model Editor Application Generates Eclipse Platform
- 33. Ecore Model for Purchase Orders is represented in Ecore as
- 44. The Code Generation Process Java Code Model Importer JET Simplified version UML Java Model ? XML Schema GenModel Ecore
- 45. The Code Generation Process Java Code Merged Java Code Model Importer JET JMerge Generated Java Code Full version UML Java Model ? XML Schema GenModel Ecore
- 53. Proxy Resolution and Demand Load PurchaseOrder p2 = p1. getNext (); p1 p1.xml next p2 p2.xml proxyURI=“ p2.xml #p2” next proxyURI=“p2.xml#p2” next <PurchaseOrder> <shipTo>John Doe</shipTo> <next> p2.xml#p2 </next> </PurchaseOrder> p1.xml
- 57. Bidirectional Reference Handshaking public interface PurchaseOrder { PurchaseOrder getNext (); void setNext (PurchaseOrder value); PurchaseOrder getPrevious (); void setPrevious (PurchaseOrder value); } Invariant imposed by the bidirectional reference: po.getNext().getPrevious() == po
- 58. Bidirectional Reference Handshaking p1. setNext (p3); p2 p1 p2 p3 previous next next previous next previous next previous change notification
- 69. Change Model
- 84. Part 2: Advanced Features of the Eclipse Modeling Framework
- 92. EcoreUtil.ProxyCrossReferencer public static void printProxiesDetails(ResourceSet resourceSet ) { int counter = 0; Map<EObject, Collection<EStructuralFeature.Setting>> map = ProxyCrossReferencer .find(resourceSet); for (Map.Entry<EObject, Collection<EStructuralFeature.Setting>> entry : map.entrySet()) { EObject proxyEObject = entry. getKey (); System.out.println ("" + ++counter + ". " + EcoreUtil.getURI(proxyEObject)); System.out.println ("Is Proxy: " + proxyEObject.eIsProxy()); for (EStructuralFeature.Setting setting : entry. getValue ()) { System.out.println ("Feature: " + setting. getEStructuralFeature ().getName()); EObject eObject = setting. getEObject (); EStructuralFeature nameFeature = eObject.eClass().getEStructuralFeature("name"); if (nameFeature != null) { System.out.println ("EObject.getName(): " + eObject.eGet(nameFeature)); } } } } 1. uri3.xmi#/0 Is Proxy: true Feature: home EObject.getName(): john
- 94. Validating Proxies public static void validateProxies(EObject eObject) { Diagnostic diagnostic = Diagnostician .INSTANCE. validate (eObject); if (diagnostic.getSeverity() == Diagnostic.ERROR) { if ( hasEveryProxyResolvesCode (diagnostic)) { System.out.println ("Broken proxies found!"); return; } } System.out.println ("Proxies are fine."); } public static boolean hasEveryProxyResolvesCode (Diagnostic diagnostic) { if (diagnostic. getCode () == EObjectValidator. EOBJECT__EVERY_PROXY_RESOLVES ) return true; for (Diagnostic childDiagnostic : diagnostic.getChildren()) { return hasEveryProxyResolvesCode (childDiagnostic); } return false; }
- 102. Enabling Cross-Resource Containment EReference houses = EcoreFactory.eINSTANCE.createEReference(); houses.setName("houses"); houses.setEType(house); houses.setUpperBound(ETypedElement.UNBOUNDED_MULTIPLICITY); houses.setContainment(true); houses. setResolveProxies ( true ); person.getEStructuralFeatures().add(houses); Dynamic Model Generated Model
- 103. Cross-Resource Containment { Library library = LibFactory.eINSTANCE.createLibrary(); Book book = LibFactory.eINSTANCE.createBook(); library .getBooks().add(book); System.out.println (library.eResource() + " - " + book.eResource()); Resource libraryResource = new ResourceImpl(URI.createURI(" lib ")); libraryResource .getContents().add( library ); System.out.println (library.eResource().getURI() + " - “ + book.eResource().getURI()); Resource bookResource = new ResourceImpl(URI.createURI(" book ")); bookResource .getContents().add( book ); System.out.println (library.eResource().getURI() + " - " + book.eResource().getURI()); bookResource .getContents().remove( book ); System.out.println (library.eResource().getURI() + " - " + book.eResource().getURI()); } null - null lib - lib lib - book lib - lib
- 108. Using a CrossReferencer { Library library = LibFactory.eINSTANCE.createLibrary(); Book book = LibFactory.eINSTANCE.createBook(); book.setTitle("EMF"); Person dave = LibFactory.eINSTANCE.createPerson(); library .getBooks().add( book ); library .getWriters().add( dave ); book .getWriters().add( dave ); Map<EObject, Collection<EStructuralFeature.Setting>> map = EcoreUtil.CrossReferencer .find(Collections.singleton( library )); Collection<EStructuralFeature.Setting> settings = map.get(dave); if (settings != null) { for (EStructuralFeature.Setting setting : settings) { if (setting. getEObject () == book && setting. getEStructuralFeature () == LibPackage.Literals. BOOK__WRITERS ) { System.out.println ("Found it. The book is amp;quot;" + book.getTitle() + "amp;quot;"); } } } } Found it. The book is "EMF"
- 110. Using the ECrossReferenceAdapter { Library library = LibFactory.eINSTANCE.createLibrary(); ECrossReferenceAdapter adapter = new ECrossReferenceAdapter (); library.eAdapters().add( adapter ); Book book = LibFactory.eINSTANCE.createBook(); book.setTitle("EMF"); Person dave = LibFactory.eINSTANCE.createPerson(); library .getBooks().add( book ); library .getWriters().add( dave ); book .getWriters().add( dave ); Collection<EStructuralFeature.Setting> settings = adapter. getNonNavigableInverseReferences (dave); for (EStructuralFeature.Setting setting : settings) { if (setting. getEObject () == book && setting. getEStructuralFeature () == LibPackage.Literals. BOOK__WRITERS ) { System.out.println ("Found it. The book is amp;quot;" + book.getTitle() + "amp;quot;"); } } } Found it. The book is "EMF"
- 118. Suppress Interfaces /** * A representation of the model object * 'Library'. * @model * @generated */ public interface Library extends EObject { /** * Returns the value of the ‘Name' attribute. * @model * @generated */ String getName(); ... } /** * A representation of the model object * 'Library'. * @model * @generated */ public class Library extends EObjectImpl implements EObject { /** * The default value of the 'Name' attribute. * @model * @generated */ protected static final NAME_EDEFAULT = null; ... }
- 145. Importers and Exporters Java model Annotated Java Model Importer EMF Model Exporter Java model UML Java model XML Schema Java model Ecore Java model ? Java model ? Java model XML Schema Java model XML Schema for XMI
- 164. Part 3: Eclipse Modeling Framework Technologies – Query, Transaction, Validation
- 176. Static Constraint Provider <extension point=" org.eclipse.emf.validation.constraintProviders "> < category name ="Library Constraints" id ="com.example.library"> <constraintProvider> < package namespaceUri ="http:///www.eclipse.org/Library/1.0.0"/> <constraints categories ="com.example.library"> <constraint lang ="Java" class ="com.example.constraints.UniqueLibraryName" severity ="WARNING" mode ="Batch" name="Library Must have a Unique Name" id="com.example.library.LibraryNameIsUnique" statusCode="1"> <description>Libraries have unique names.</description> <message>{0} has the same name as another library.</message> < target class ="Library"/> </constraint> </constraints> </constraintProvider> </extension>
- 187. Creating Constraints public class LibraryNameIsUnique extends AbstractConstraint { public IStatus validate (IValidationContext ctx) { Library target = (Library) ctx. getTarget (); // object to validate // does this library have a unique name? Set<Library> libs = findLibrariesWithName(target.getName()); if (libs.size() > 1) { // report this problem against all like-named libraries ctx. addResults (libs); // don’t need to validate these other libraries libs.remove(target); ctx. skipCurrentConstraintFor (libs); return ctx.createFailureStatus(new Object[] { target, libs}); } return ctx. createSuccessStatus (); } }
- 190. Reporting Problems public class ProblemsReporter implements IValidationListener { public void validationOccurred (ValidationEvent event) { if (event. matches (IStatus.WARNING | IStatus.ERROR)) { // fabricate a multi-status for the MarkerUtil to consume List results = event. getValidationResults (); IConstraintStatus multi = new MultiStatus( "com.example.MyPlugin", 1, (IStatus[])results.toArray(new IStatus[results.size()]), "Problems were found by validation", null); try { // create problem markers on the appropriate resources MarkerUtil.createMarkers (multi); } catch ( CoreException e ) { // creation of problem markers failed for some reason MyPlugin.getLog().log(e.getStatus()); } } } }
Editor's Notes
- You will also need to: - manually change the JDK compliance level in the Java Compiler project properties or workspace preferences - Update the JRE container in the project’s classpath (use the Plug-in Manifest Editor: on the overview page, select “Update the classpath settings”)
- Inverse References - Finding the opposite of a unidirectional association
- Initially the arrows are proxies and when the references in Resource1 are resolved, they are replaced by the actual object from Resource2. The 2 nd proxy will be a proxy until it is accessed. When the 1 st proxy is resolved Resource2 is loaded into the ResourceSet but that doesn’t resolve all the proxies.
- The cross referencers check the containment tree of an EObject. Make it clear that a proxy is not “referenced” – this is a “transient” state.
- ECoreUtil.CrossReferencer is a convenient utility class for locating cross-references (that is, non-containment references) in the containment tree, or trees, rooted at a specified EMF object, resource, or resource set, or arbitrary collection of all three. The result of the search is stored in the cross-referencer’s base HashMap. Entries are keyed by reference targets, and their values are the collections of EStructuralFeature.Settings that identify all the source object-feature pairs referencing the keyed target. ECoreUtil.ExternalCrossReferencer is a convenient utility class for locating external cross-references in the containment tree, or trees, rooted at a specified EMF object, resource, or resource set, or arbitrary collection of all three. An external cross-reference is one that has a target that is not within the containment structure rooted at the object(s) being searched. ECoreUtil.ProxyCrossReferencer is a convenient utility class for locating proxies in the containment tree, or trees, rooted at a specified EMF object, resource, or resource set, or arbitrary collection of all three. ECoreUtil.UnresolvedProxyCrossReferencer is a convenient utility class for locating unresolvable (broken) proxies in the containment tree, or trees, rooted at a specified EMF object, resource, or resource set, or arbitrary collection of all three. ECoreUtil.UsageCrossReferencer is a convenient utility class for locating cross-references in the containment tree, or trees, rooted at a specified EMF object, resource, or resource set, or arbitrary collection of all three, with targets that are specific objects of interest. One or more objects of interest can be passed to the static find() or findAll() methods, respectively, which in turn construct an instance, with the search root(s), and then call their corresponding findUsage() or findAllUsage() instance methods.
- Is exposed on InternalEObject
- Explains why the name “CrossReferencer”. This is an informal qualification.
- As explained in the “Introduction to EMF” tutorial, the EObjectValidator is used as base of generated validators and directly for packages without additional constraints defined.
- Not always can we choose the “proxy handling” option we would like to…
- Formatted string: /, encoded, … Encoding is done by Converting the character string into a sequence of bytes using UTF-8 Convert each character that is not an ASCII letter or digit into %HH, where HH is the hexadecimal value of the byte URL: Resources that can be accessed with existing protocols URN: “Intended to serve as persistent, location-independent, resource identifiers” oasis urn: http://rfc3121.x42.com/
- URI.encodeFragment(String) can be used to produce a valid fragment.
- The default value of the “Resolve Proxies” attribute in an Ecore model is true.
- We could also call book.eContainer().eResource.getURI() instead of just library.eResource().getURI(), to illustrate that the book hasn't been removed from its container (although, that's kind of obvious from the fact that it ends up back in the same resource as the library)…
- Should also mention generated editor support for containment proxies (Control / Uncontrol menu items)…
- The question we want to answer is: what books were written by Dave? We could also use the UsageCrossReferencer…
- Why are we not defining what an ECrossReferenceAdapter is? Because we (should) know what a CrossReferencer and an Adapter are…
- The question we want to answer is: what books were written by Dave?
- This is not used by the generated UI to decided whether an editor is dirty or not - EMF.Edit monitors the state of the command stack of the EditingDomain…
- Resource.Internal, like InternalEObject and EStructuralFeature.Internal, is not really an “internal” API – it’s an API of less commonly used implementation oriented methods… all resources are assumed to implement this interface, and do so by virtue of extending ResourceImpl.
- Generates implementation classes without separate interface declarations Set the value of the ‘Suppress Interfaces’ generator model property to ‘true’
- Generates code without a package interface declaring metadata accessors and constants - these are generated into the package implementation, instead - Factory doesn’t extend EFactory Set the value of the ‘Suppress EMF Meta Data’ generator model property to ‘true’
- Generates code where interfaces for modeled root classes extend a specified interface, or nothing at all Clear or set the value of the ‘Root Extends Interface’ generator model property - Qualified name of interface, which need not extend EObject
- Generates code without @model tags in the Javadoc Set the value of the ‘Suppress EMF Model Tags’ generator model property to ‘true’
- Generates methods for features and operations which use standard Java collection and object types instead of those from EMF (e.g. EList, EMap, EObject) Set the value of the ‘Suppress EMF Types’ generator model property to ‘true’
- Header.javajetinc is an example of a template that should perhaps always be replaced – to contain your copyright.
- Dynamic “placeholder” template can also add required imports for compiling the template (in case the insertions reference new types). Need to reference default template “container” in JET project settings – i.e. templates;@/org.eclipse.emf.codegen.ecore/templates.
- Dynamic “placeholder” template can also add required imports for compiling the template (in case the overrides reference new types). Need to reference default template “container” in JET project settings – i.e. templates;@/org.eclipse.emf.codegen.ecore/templates.
- Of course, there is always a trade-off between time and space concerns…
- Of course, virtual feature delegation has a (significant) performance cost. We are also working on a VirtualEObjectImpl which will use virtual slots instead of a properties holder…
- OPTION_DEFER_IDREF_RESOLUTION Option value: Boolean This option can be enabled to defer resolving references within a resource until the whole document has been parsed. The default strategy is to try to resolve each reference as it is encountered and then, at the end, resolve any ones that failed. This wastes time looking up forward references that do not exist yet, which, if you're using intrinsic IDs, can involve iterating over every object in the resource. OPTION_USE_PARSER_POOL Option value: org.eclipse.emf.ecore.xmi.XMLParserPool We strongly encourage to set this option for EMF load operation. This option is used to provide a parser pool, from which SAXParser instances are created and reused. XMLParserPool defines a simple interface for obtaining and releasing parsers based on their features and properties. Specifying a parser pool, such as an instance of the default implementation, XMLParserPoolImpl, can improve performance dramatically when a resource performs repeated loads. A single parser pool can also be shared among multiple resources. Default implementation is also thread-safe. OPTION_USE_XML_NAME_TO_FEATURE_MAP Option value: java.util.Map This option can be used to share the cache of mappings between qualified XML names (namespace + local name) and corresponding Ecore features across invocations of load(), or even among resources. It can take some time to determine these associations, since they can be affected by ExtendedMetaData or an XMLMap, so they are cached during a load. If you use this option to specify the same map for several loads, that instance will be used as the cache, improving the performance for all but the first. You can share a single map among multiple resources, unless they load different models with conflicting qualified names.
- OPTION_USE_CACHED_LOOKUP_TABLE Option value: java.util.List Specify a list as a place holder for caching information during the subsequent saving of XML documents. This option can improve performance for serialization (saving) of multiple XML resources. This option is similar to the OPTION_USE_XML_NAME_TO_FEATURE_MAP which is used for deserialization (loading). OPTION_USE_DEPRECATED_METHODS Option value: Boolean Use methods that were deprecated in EMF. The default value is true. To improve deserialization performance turn this option to false. The methods affected are: XMLHelper#createObject(org.eclipse.emf.ecore.EFactory, EClassifier) XMLHander#handleNamespaceAttribs() XMLHandler#createObjectFromFactory(EFactory factory, String typeName) XMLLoadImpl#getEncoding() Note: if you use this option the SAX parser used for parsing documents must be namespace-aware parser, i.e. the namespaces should be turned on for the parser used. The default parser implementation is not namespace-aware. To turn on namespaces, either use OPTION_USE_PARSER_POOL or overwrite XMLLoadImpl#makeParser()
- OPTION_FLUSH_THRESHOLD Option value: Integer This option can be used to specify a maximum number of characters to allow in the output stream before flushing it. This reduces the memory used in serializing a large file, but it is slower than the default behavior. OPTION_USE_CACHED_LOOKUP_TABLE Option value: java.util.List This option provides a placeholder to cache information about structure of the model. (using qualified XML names as a key for caching information). When possible, the same placeholder list should be shared among resources, unless you intent to serialize instances of different models. OPTION_CONFIGURATION_CACHE Option value: Boolean This option can be enabled to cache and reuse generic data in repeated save operations, avoiding the cost of reinitializing the data. This option is save to use when serializing instances of the same model.
- OPTION_FORMATTED Option value: Boolean This option is used to disable formatting of documents, omitting whitespaces and line brakes, to improve the performance of saving and, subsequently, loading the resulting document. This means fewer bytes have to be written and read, but the serialization will be less human-readable. OPTION_USE_FILE_BUFFER Option value: Boolean This option can be enabled to accumulate output during serialization in a temporary file, rather than an in-memory buffer. This reduces the memory used in serializing a large file, but it is slower than the default behavior.
- Every solid box in this picture represents a way to describe a modeled domain.
- The HTML exporter even understands generics in models, highlighting things like type parameters
- When exporting a model as a schema, we would need the qualified name of the package if we were adding an Ecore package annotation.
- Before the Importer and Exporter hooks, we used to see all types of approaches to, for example, convert a proprietary format to Ecore: menu items, separate application, tool bar buttons, import wizard, …
- That’s all one needs to know to provide an importer or an exporter. The rest of this section will address the “non-mandatory” framework we’ve created to make it easier to write converters.
- Ideally, XML references would be based on identifiers, e.g. UUIDs.
- The Ecore2Ecore mapping editor is much like the XSD2Ecore mapping editor.
- The Ecore2XML editor is just a standard EMF-generated editor.
- These steps cab be done in a customized resource factory implementation to set the default load/save options for all resources managed by the factory…
- Could also be done by a customized editor or programmatically when calling the load()/save() methods.