• Check out this SlideShare Presentation : Xtext Webinar http://slidesha.re/7Uu7e #

Xtext is an extended EBNF language for describing domain-specific languages (DSLs). The extended scope of expressions (compared to EBNF) allows the definition of a corresponding meta-model. Source code can be read by the Xtext parser component MweReader. MweReader is a configurable MWE workflow component, able to transform any artefact in conformity to an Xtext DSL into the target model.

However, some use cases may require transformation of more than one source file. In such cases, every single artefact needs its own workflow setup. Even then it is not possible

• defining multiple input files and directories (recursively read all files in a directory and its subdirectories ending with the DSL’s file extension)
• merging all target models into one

In such cases, another workflow component may help, called MweBulkReader. It combines all features of MweReader plus the aforementioned ones: Define multiple resources, files or folders. Folders are searched for all files with the DSL’s file extension (or a custom one). For each and every artefact MweReader is called, with a consecutively numbered output slot name (“model_{1}” set per default). In the end all created output slots are merged into one slot (named “model” or redefined by property “outputSlot”).

import java.io.File;
import java.io.FilenameFilter;
import java.io.IOException;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.Vector;
import java.util.Map.Entry;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.mwe.core.WorkflowContext;
import org.eclipse.emf.mwe.core.issues.Issues;
import org.eclipse.emf.mwe.core.lib.AbstractWorkflowComponent2;
import org.eclipse.emf.mwe.core.monitor.ProgressMonitor;
import org.eclipse.xtext.ISetup;
import org.eclipse.xtext.MweReader;
import org.eclipse.xtext.resource.XtextResourceFactory;

/**
 * Identical to MweReader but is further able to read a list of resources
 * specified at <sourceDirectory>s and <Uri>s.
 *
 * If a resource is a directory it is recursively scanned for files, filtered by extension.
 * File extension is defined by registered Xtext DSL or can be manually changed with <extension>.
 * Files are parsed into enumerated model slots 'model_{0}'s or <outputSlotFormat>s
 * The parser class has to be set by <register>.
 * The parser's class path may be set with <classpathURIContext>.
 * The parser's validation flag can be set using <validate>.
 * A list of all parsed models is made available at slot 'model' or <outputSlot>
 *
 * @author Andreas Rentschler
 */
public class MweBulkReader extends AbstractWorkflowComponent2 {

	public static final String DEFAULT_OUTPUT_SLOT_FORMAT = "model_{0}";
	public static final String DEFAULT_OUTPUT_SLOT = "model";

	private final Log log = LogFactory.getLog(getClass());

	private ISetup setup = null;

	public void setRegister(ISetup setup) {
		this.setup  = setup;
	}

	private String extension = null;

	public void setExtension(String extension) {
		this.extension = extension;
	}

	private String outputSlotFormat = DEFAULT_OUTPUT_SLOT_FORMAT;

	public void setOutputSlotFormat(String outputSlotFormat) {
		this.outputSlotFormat = outputSlotFormat;
	}

	private String outputSlot = DEFAULT_OUTPUT_SLOT;

	/**
	 * Sets an accumulation model slot name. If set (non-null and non-empty),
	 * then a {@link List} of all models read in, is stored in the designated
	 * model slot. This way, using the {@link #getModelSlots()} method is not
	 * necessary.
	 */
	public void setOutputSlot(String outputSlot) {
		this.outputSlot = outputSlot;
	}

	private List<String> sourceDirectories = new ArrayList<String>();

	public void addSourceDirectory(String path) {
		sourceDirectories.add(path);
	}

	public void addUri(String path) {
		sourceDirectories.add(path);
	}

	private Object classpathURIContext;

	public Object getClasspathURIContext() {
        return classpathURIContext;
    }

    public void setClasspathURIContext(Object classpathURIContext) {
        this.classpathURIContext = classpathURIContext;
    }

	private boolean validate = true;

	public void setValidate(boolean validate) {
		this.validate = validate;
	}

	@Override
	protected void checkConfigurationInternal(Issues issues) {
		if (setup == null)
			issues.addError(this,"No setup has been registered (property 'register')");
		if (extension == null) {
			// register file extension
			setup.createInjectorAndDoEMFRegistration();

			// take latest file extension registered to Xtext
			for (Entry<String, Object> e : Resource.Factory.Registry.INSTANCE.getExtensionToFactoryMap().entrySet()) {
				if (e.getValue() instanceof XtextResourceFactory) {
					extension = e.getKey();
				}
			}
			if (extension != null)
				log.info(getComponentName() + "(" + getId() + "): No explicit file extension configured, found '" + extension + "'");
		}
		if (extension == null)
			issues.addError(this,"No file extension has been registered (property 'register')");
		if (sourceDirectories.isEmpty())
			issues.addError(this,"No resource uri configured (property 'uri')");
		if (outputSlot == null)
			issues.addWarning("no explicit output slot configured, using + '" + outputSlot + "'");
	}

	private int freeSlot = 0;
	private List<String> modelSlots = new ArrayList<String>();
	private WorkflowContext ctx;
	private ProgressMonitor monitor;
	private Issues issues;

	@Override
	protected void invokeInternal(WorkflowContext ctx, ProgressMonitor monitor, Issues issues) {
		this.ctx = ctx;
		this.monitor = monitor;
		this.issues = issues;

		for (String directory : sourceDirectories) {
			File resource = new File(directory);

			if (!resource.exists()) {
				issues.addError("'" + resource + "' does not exist!");
			} else {
				if (resource.isDirectory())
					addComponentsForDirectory(resource);
				else
					addComponentForFile(resource);
			}
		}

		// merge all models into one
		List<Object> list = new ArrayList<Object>();
		for (String slotName : modelSlots) {
			if (ctx.get(slotName) == null) {
				// ensure that list of models doesn't contain EVoid elements
				log.info(getComponentName() + "(" + getId() + "): Skipping empty slot '" + slotName + "'");
				continue;
			}
			list.add(ctx.get(slotName));
		}
		ctx.set(outputSlot, list);
	}

	@Override
	public String getLogMessage() {
		return "Loading " + sourceDirectories.size() + (sourceDirectories.size() == 1? " resource" : " resources");
	}

	private void addComponentsForDirectory(File dir) {
		log.info(getComponentName() + "(" + getId() + "): Registering models from path '" + dir + "'");
		Collection<File> files = listFiles(dir, new FilenameFilter() {
			public boolean accept(File directory, String filename) {
				if (extension == null) return false;

				int index = filename.lastIndexOf('.');
				if (index < 0) {
					return false;
				}
				return filename.substring(index + 1).equals(extension);
			}
		}, true);
		for (File f : files) {
			addComponentForFile(f);
		}
	}

	private void addComponentForFile(File f) {
		String uri = null;
		try {
			uri = URI.createFileURI(f.getCanonicalPath()).toFileString();
		} catch (IOException e) {
			e.printStackTrace();
		}
		String slot = MessageFormat.format(outputSlotFormat, freeSlot++);
		modelSlots.add(slot);

		String shortUri = (uri.length() > 57) ? "..." + uri.substring(uri.length() - 60) : uri;
		log.info(getComponentName() + "(" + getId() + "): Parsing file:" + shortUri + " into slot '" + slot + "'");

		MweReader reader = new MweReader();
		reader.setContainer(getContainer());
		reader.setLocation(getLocation());
		//reader.setSkipOnErrors(true);
		reader.setClasspathURIContext(classpathURIContext);
		reader.setValidate(validate);
		reader.setRegister(setup);
		reader.setOutputSlot(slot);
		reader.setUri("file:" + uri);
		try {
			reader.invoke(ctx, monitor, issues);
		} catch (IndexOutOfBoundsException e) {
			// catch weird bug (files producing no elements (not even a container element, maybe some comments)
			log.info(getComponentName() + "(" + getId() + "): Skipping file because it is empty");
		} catch (Exception e) {
			log.info(getComponentName() + "(" + getId() + "): Skipping file because of exception " + e);
		}
	}

	// list files in a directory filtered, optionally recursively
	private Collection<File> listFiles(File directory,
			FilenameFilter filter, boolean recurse) {
		Vector<File> files = new Vector<File>();
		File[] entries = directory.listFiles();

		for (File entry : entries) {
			if (filter == null || filter.accept(directory, entry.getName())) {
				files.add(entry);
			}

			if (recurse && entry.isDirectory()) {
				files.addAll(listFiles(entry, filter, recurse));
			}
		}
		return files;
	}

}

This is one example of application in a workflow configuration .mwe:

<workflow>
...
	<!-- parse all Xtext artefacts in files ${sourceFile1}, ${sourceFile2} and folders ${sourcePath1}, ${sourcePath2} into slot 'mergedModel' -->
	<component id="dsl2model" class="my.classpath.to.bulk.reader.MweBulkReader">
		<!-- this class has been generated by the xtext generator -->
		<register class="my.classpath.to.dsl.strategy.XXXStandaloneSetup"/>
		<uri value="file:${sourceFile1}" />
		<uri value="file:${sourceFile2}" />
		<sourceDirectory value="${sourcePath1}" />
		<sourceDirectory value="${sourcePath2}" />
		<outputSlot value="mergedModel" />
	</component>
...
</workflow>

• co-writing a paper on my diploma thesis #

Currently I’m working on my diploma thesis. I am developing a graphical dataflow editor which gives users the ability to visually connect filter components defined in a C++ framework. A generator finally creates the corresponding C++ code setting all components up. As development platform I have chosen the Eclipse/Java platform paired with these frameworks and technologies:

• openArchitectureWare framework (oAW) fully defines a model-driven workflow according to the MDSD approach. It highly builds upon OMG’s MDA standards (CIM>PIM>PSM>Code, QVT, OCL, UML, MOF), though sometimes lowering complexy and making use of modeling solutions offered by Eclipse; for example they use EMF/Ecore, a subset of MOF, UML’s metamodel offered by Eclipse. oAW incorporates different technologies (languages as well as so-called cartridges) connected by a workflow definition file:
  • oAW Xtext gives you the ability to specify your own textual domain-specific language (DSL) through enhanced EBNF grammar rules, for which it creates a fully-blown Eclipse editor (syntactical highlighting, outline view, keyword completion, error viualization), an Ecore meta model, as well as a parser for transforming a DSL instance file into a meta model instance.
  • oAW Xtend lets you transform one meta model instance into another meta model instance using a QVT-like rule style and OCL expression.
  • oAW Xpand is a pattern-based language. It helps you transform models into code.
  • oAW Checks is a language for specifying model constraints. Like in any oAW technology, OCL is used. A GMF Adaptor enables you to use constraints defined in Checks in your (visual) GMF model editor, you don’t have to define each and every constraint again.
  • the oAW Recipe framework is for marking parts of generated artifacts which have to be further edited by hand (most MDSD-projects contain non-repeating parts, they have to be manually written).
  • a UML2 Adaptor let’s you decide to not use EMF/Ecore as meta-metamodel, but UML2.
• the Eclipse Modeling Framework (EMF) is an implementation of essential MOF (EMOF), a subset of UML’s meta language MOF, coined to the Java platform.
• Eclipse Graphical Editing Framework (GEF) and Graphical Modeling Framework (GMF). While GEF is a framework for manually writing graphical editors embedded into the Eclipse IDE, GMF goes one step further: just create the underlying Ecore model and some Ecore models of your editor appearance and a mapping between model, editing elements and toolbox elements and voila, an EMF interface and EMF and GEF editor plugins are automatically generated.
• last but not least I’m using Eclipse Subversion (SVN) as version control system. On a Mac there’s just a
svnadmin create /Volumes/USBSTICK/SVNRepository
  on the terminal to create a local repository on my USB stick. In Subclipse, I added the location URL file:///Volumes/USBSTICK/SVNRepository as a new repository and did an initial check-out. Cf. this tutorial

.

Die neue Seite für den großen Bruder des VisualCube, den VisualCube1e3, ist fertig, zu finden unter der URL

http://www.visualcube.org/1e3.

In den kommenden Wochen wird sie mit mehr und mehr Inhalten über den 2,75m großen Würfel gefüllt werden.
Die dynamische Lichtskulptur wird an der HfG Karlsruhe konstruiert. Die Finanzierung übernimmt die MFG Stiftung im Rahmen des Karl-Steinbuch-Stipendiums. Das Gerät ist das erste seiner Art, das ohne besonderen Aufwand in Betrieb genommen werden und auf einfachste Weise mit der Skriptsprache PROCESSING programmiert werden kann.