Fixed: [Issue 18] IllegalStateException: No IResourceServiceProvider found in registry for uri platform:/resource/javatest/src/folder1 https://code.google.com/p/protobuf-dt/issues/detail?id=18 Replaced default implementation of LoadOnDemandResourceDescriptions with a custom one that does not throw IllegalStateException if an IResourceDescription cannot be obtained for a given URI.

diff --git a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/ProtobufRuntimeModule.java b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/ProtobufRuntimeModule.java
index 5492360..929812b 100644
--- a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/ProtobufRuntimeModule.java
+++ b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/ProtobufRuntimeModule.java

@@ -13,6 +13,7 @@
 import org.eclipse.xtext.scoping.impl.*;
 
 import com.google.eclipse.protobuf.naming.ProtobufQualifiedNameProvider;
+import com.google.eclipse.protobuf.scoping.ResourceDescriptions;
 import com.google.eclipse.protobuf.scoping.SimpleImportUriResolver;
 import com.google.inject.Binder;
 
@@ -34,4 +35,8 @@
   public void configureImportUriResolver(Binder binder) {
     binder.bind(ImportUriResolver.class).to(SimpleImportUriResolver.class);
   }
+
+  public void configureLoadOnDemandResourceDescriptions(Binder binder) {
+    binder.bind(LoadOnDemandResourceDescriptions.class).to(ResourceDescriptions.class);
+  }
 }

diff --git a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/scoping/ResourceDescriptions.java b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/scoping/ResourceDescriptions.java
new file mode 100644
index 0000000..f71a0e2
--- /dev/null
+++ b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/scoping/ResourceDescriptions.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2011 Google Inc.
+ *
+ * All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse
+ * Public License v1.0 which accompanies this distribution, and is available at
+ *
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+package com.google.eclipse.protobuf.scoping;
+
+import static com.google.common.collect.Iterables.*;
+import static org.eclipse.xtext.EcoreUtil2.getResource;
+
+import java.util.Collection;
+
+import org.eclipse.emf.common.util.URI;
+import org.eclipse.emf.ecore.resource.Resource;
+import org.eclipse.xtext.resource.*;
+import org.eclipse.xtext.resource.IResourceDescription.Manager;
+import org.eclipse.xtext.scoping.impl.LoadOnDemandResourceDescriptions;
+
+import com.google.common.base.Function;
+import com.google.common.base.Predicates;
+import com.google.inject.Inject;
+
+/**
+ * Similar to <code>{@link LoadOnDemandResourceDescriptions}</code> but it does not throw exceptions if a
+ * <code>{@link IResourceDescription}</code> cannot be obtained from a <code>{@link URI}</code>.
+ *
+ * @author alruiz@google.com (Alex Ruiz)
+ */
+public class ResourceDescriptions extends LoadOnDemandResourceDescriptions {
+
+  private IResourceDescriptions delegate;
+  private Collection<URI> validUris;
+  private Resource context;
+
+  @Inject private IResourceServiceProvider.Registry serviceProviderRegistry;
+
+  @Override
+  public void initialize(IResourceDescriptions newDelegate, Collection<URI> newValidUris, Resource newContext) {
+    this.delegate = newDelegate;
+    this.validUris = newValidUris;
+    this.context = newContext;
+  }
+
+  @Override public Iterable<IResourceDescription> getAllResourceDescriptions() {
+    return filter(transform(validUris, new Function<URI, IResourceDescription>() {
+      public IResourceDescription apply(URI from) {
+        return getResourceDescription(from);
+      }
+    }), Predicates.notNull());
+  }
+
+  @Override public boolean isEmpty() {
+    return validUris.isEmpty();
+  }
+
+  @Override protected Iterable<? extends ISelectable> getSelectables() {
+    return getAllResourceDescriptions();
+  }
+
+  @Override public IResourceDescription getResourceDescription(URI uri) {
+    IResourceDescription result = delegate.getResourceDescription(uri);
+    if (result == null) return result;
+    Resource resource = getResource(context, uri.toString());
+    if (resource == null) return null;
+    IResourceServiceProvider provider = serviceProviderRegistry.getResourceServiceProvider(uri);
+    if (provider == null) return null;
+    Manager manager = provider.getResourceDescriptionManager();
+    if (manager == null) return null;
+    return manager.getResourceDescription(resource);
+  }
+}