Better error handling in GWT UI.

src/server/gwt-client/src/se/chalmers/cs/gf/gwt_translate/client/CompletionOracle.java

@@ -2,20 +2,28 @@ package se.chalmers.cs.gf.gwt_translate.client;
 
 import com.google.gwt.user.client.ui.SuggestOracle;
 
+import com.google.gwt.core.client.GWT;
+
 import java.util.*;
 
 public class CompletionOracle extends SuggestOracle {
 
     private GF gf;
 
-    private List<String> inputLangs;
+    private ErrorHandler errorHandler;
+
+    private List<String> inputLangs = null;
 
     private GFRequest gfRequest = null;
 
 
     public CompletionOracle (GF gf) {
+	this(gf, null);
+    }
+
+    public CompletionOracle (GF gf, ErrorHandler errorHandler) {
 	this.gf = gf;
-	inputLangs = new ArrayList<String>();
+	this.errorHandler = errorHandler;
     }
 
     public void setInputLangs(List<String> inputLangs) {
@@ -26,6 +34,14 @@ public class CompletionOracle extends SuggestOracle {
 	return inputLangs;
     }
 
+    public void setErrorHandler(ErrorHandler errorHandler) {
+	this.errorHandler = errorHandler;
+    }
+
+    public static interface ErrorHandler {
+	public void onError(Throwable e);
+    }
+
     public static class CompletionSuggestion implements SuggestOracle.Suggestion {
 	private String string;
 	public CompletionSuggestion(String string) {
@@ -49,14 +65,19 @@ public class CompletionOracle extends SuggestOracle {
 
 	gfRequest = gf.complete(request.getQuery(), getInputLangs(), null, request.getLimit(), 
 		    new GF.CompleteCallback() {
-		public void onCompleteDone(GF.Completions completions) {
+			public void onResult(GF.Completions completions) {
-		    Collection<CompletionSuggestion> suggestions = new ArrayList<CompletionSuggestion>();
+			    Collection<CompletionSuggestion> suggestions = new ArrayList<CompletionSuggestion>();
-		    for (int i = 0; i < completions.length(); i++) {
+			    for (int i = 0; i < completions.length(); i++) {
-			String text = completions.get(i).getText();
+				String text = completions.get(i).getText();
-			suggestions.add(new CompletionSuggestion(text));
+				suggestions.add(new CompletionSuggestion(text));
-		    }
+			    }
-		    callback.onSuggestionsReady(request, new SuggestOracle.Response(suggestions));
+			    callback.onSuggestionsReady(request, new SuggestOracle.Response(suggestions));
-		}
+			}
+
+			public void onError(Throwable e) {
+			    errorHandler.onError(e);
+			}
+
 	    });
     }    
 

src/server/gwt-client/src/se/chalmers/cs/gf/gwt_translate/client/GF.java

@@ -21,16 +21,19 @@ public class GF {
 	this.baseURL = baseURL;
     }
 
+    public static interface GFCallback<T extends JavaScriptObject> {
+	public void onResult (T result) ;
+	public void onError (Throwable e) ;
+    }
+
     /* Languages */
 
     public GFRequest languages (final LanguagesCallback callback) {
-	return sendRequest("languages", null, new JSONRequestCallback() {
+	return sendRequest("languages", null, callback);
-		public void onJSONReceived(JSONValue json) {
-		    callback.onLanguagesDone((Languages)json.isArray().getJavaScriptObject().cast());
-		}
-	    });
     }
 
+    public interface LanguagesCallback extends GFCallback<Languages> { }
+
     public static class Languages extends JsArray<Language> {
 	protected Languages() { }
     }
@@ -43,11 +46,6 @@ public class GF {
         public final native boolean canParse() /*-{ return this.canParse; }-*/;
     }
 
-
-    public interface LanguagesCallback {
-	public void onLanguagesDone (Languages languages);
-    }
-
     /* Translation */
 
     public GFRequest translate (String input, List<String> fromLangs, String cat, List<String> toLangs, 
@@ -65,13 +63,11 @@ public class GF {
 		args.add(new Arg("to", to));
 	    }
 	}
-	return sendRequest("translate", args, new JSONRequestCallback() {
+	return sendRequest("translate", args, callback);
-		public void onJSONReceived(JSONValue json) {
-		    callback.onTranslateDone((Translations)json.isArray().getJavaScriptObject().cast());
-		}
-	    });
     }
 
+    public interface TranslateCallback extends GFCallback<Translations> {  }
+
     public static class Translations extends JsArray<Translation> {
 	protected Translations() { }
     }
@@ -84,10 +80,6 @@ public class GF {
         public final native String getText() /*-{ return this.text; }-*/;
     }
 
-    public interface TranslateCallback {
-	public void onTranslateDone (Translations translations);
-    }
-
     /* Completion */
     
     public GFRequest complete (String input, List<String> fromLangs, String cat, int limit, final CompleteCallback callback) {
@@ -100,13 +92,11 @@ public class GF {
 	}
 	args.add(new Arg("cat", cat));
 	args.add(new Arg("limit", limit));
-        return sendRequest("complete", args, new JSONRequestCallback() {
+        return sendRequest("complete", args, callback);
-		public void onJSONReceived(JSONValue json) {
-		    callback.onCompleteDone((Completions)json.isArray().getJavaScriptObject().cast());
-		}
-	    });
     }
 
+    public interface CompleteCallback extends GFCallback<Completions> { }
+
     public static class Completions extends JsArray<Translation> {
 	protected Completions() { }
     }
@@ -118,44 +108,41 @@ public class GF {
         public final native String getText() /*-{ return this.text; }-*/;
     }
 
-    public interface CompleteCallback {
-	public void onCompleteDone (Completions completions);
-    }
-
-
     /* Utilities */
 
-    public interface JSONRequestCallback {
+    private <T extends JavaScriptObject> GFRequest sendRequest (String resource, List<Arg> vars, final GFCallback<T> callback) {
-	public void onJSONReceived(JSONValue json);
-    }
-
-    private GFRequest sendRequest (String resource, List<Arg> vars, final JSONRequestCallback callback) {
 	String url = baseURL + "/" + resource + "?" + buildQueryString(vars);
 	RequestBuilder builder = new RequestBuilder(RequestBuilder.GET, url);
+	builder.setTimeoutMillis(30000);
 	builder.setHeader("Accept","text/plain, text/html;q=0.5, */*;q=0.1");
 	Request request = null;
 
 	try {
 	    request = builder.sendRequest(null, new RequestCallback() {
 		    public void onError(Request request, Throwable e) {
-			GWT.log("onError called", e);
+			callback.onError(e);
 		    }
 		    
 		    public void onResponseReceived(Request request, Response response) {
 			if (200 == response.getStatusCode()) {
-			    callback.onJSONReceived(JSONParser.parse(response.getText()));
+			    callback.onResult((T)eval(response.getText()).cast());
 			} else {
-			    GWT.log("Response not OK: " + response.getStatusCode() + ". " + response.getText(), null);
+			    RequestException e = new RequestException("Response not OK: " + response.getStatusCode() + ". " + response.getText());
+			    callback.onError(e);
 			}
 		    }
 		});
 	} catch (RequestException e) {
-	    GWT.log("Failed to send request", e);
+	    callback.onError(e);
 	}
 
 	return new GFRequest(request);
     }
 
+    private static native JavaScriptObject eval(String json) /*-{ 
+        return eval('(' + json + ')');
+    }-*/;
+
     private static class Arg {
 	public final String name;
 	public final String value;

src/server/gwt-client/src/se/chalmers/cs/gf/gwt_translate/client/Translate.java

@@ -4,6 +4,7 @@ import com.google.gwt.core.client.EntryPoint;
 import com.google.gwt.user.client.ui.Button;
 import com.google.gwt.user.client.ui.ChangeListener;
 import com.google.gwt.user.client.ui.ClickListener;
+import com.google.gwt.user.client.ui.DockPanel;
 import com.google.gwt.user.client.ui.DialogBox;
 import com.google.gwt.user.client.ui.Grid;
 import com.google.gwt.user.client.ui.Image;
@@ -17,6 +18,8 @@ import com.google.gwt.user.client.ui.VerticalPanel;
 import com.google.gwt.user.client.ui.Widget;
 import com.google.gwt.user.client.ui.KeyboardListenerAdapter;
 
+import com.google.gwt.core.client.GWT;
+
 import com.google.gwt.user.client.Window;
 
 import java.util.ArrayList;
@@ -34,6 +37,7 @@ public class Translate implements EntryPoint {
     private List<String> fromLangs;
     private List<String> toLangs;
     private VerticalPanel outputPanel;
+    private Label statusLabel;
 
     private void addTranslation(String text) {
 	Label l = new Label(text);
@@ -43,13 +47,16 @@ public class Translate implements EntryPoint {
 
     private void translate() {
 	gf.translate(suggest.getText(), fromLangs, null, toLangs, new GF.TranslateCallback() {
-		public void onTranslateDone (GF.Translations translations) {
+		public void onResult (GF.Translations translations) {
 		    outputPanel.clear();
 		    for (int i = 0; i < translations.length(); i++) {
 			GF.Translation t = translations.get(i);
 			addTranslation(t.getText());
 		    }
 		}
+		public void onError (Throwable e) {
+		    showError("Translation failed", e);
+		}
 	    });
     }
 
@@ -64,15 +71,26 @@ public class Translate implements EntryPoint {
 	return l;
     }
 
+    private void setStatus(String msg) {
+	statusLabel.setText(msg);
+    }
+
+    private void showError(String msg, Throwable e) {
+	GWT.log(msg, e);
+	setStatus(msg);
+    }
+
     public void onModuleLoad() {
     
-	final PopupPanel loading = new PopupPanel();
+	statusLabel = new Label("Loading...");
-	loading.add(new Label("Loading..."));
-	loading.center();
 
 	gf = new GF(gfBaseURL);
 
-	oracle = new CompletionOracle(gf);
+	oracle = new CompletionOracle(gf, new CompletionOracle.ErrorHandler() {
+		public void onError(Throwable e) {
+		    showError("Completion failed", e);
+		}
+	    });
 
 	suggest = new SuggestBox(oracle);
 	suggest.addKeyboardListener(new KeyboardListenerAdapter() {
@@ -133,9 +151,10 @@ public class Translate implements EntryPoint {
 	vPanel.add(outputPanel);
 
 	RootPanel.get().add(vPanel);
+	RootPanel.get().add(statusLabel, (Window.getClientWidth() - statusLabel.getOffsetWidth())/2, (Window.getClientHeight() - statusLabel.getOffsetHeight()));
 
 	gf.languages(new GF.LanguagesCallback() {
-		public void onLanguagesDone(GF.Languages languages) {
+		public void onResult(GF.Languages languages) {
 		    for (int i = 0; i < languages.length(); i++) {
 			GF.Language l = languages.get(i);
 			if (l.canParse()) {
@@ -144,7 +163,11 @@ public class Translate implements EntryPoint {
 			toLangBox.addItem(l.getName());
 		    }
 
-		    loading.hide();
+		    setStatus("Loaded languages.");
+		}
+
+		public void onError (Throwable e) {
+		    showError("Error getting language information", e);
 		}
 	    });