diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/RpcStatus.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/RpcStatus.java
index 76ce3844e0..955c8e2648 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/RpcStatus.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/RpcStatus.java
@@ -56,6 +56,10 @@ public class RpcStatus implements RpcStartHandler, RpcCompleteHandler {
 
   @Override
   public void onRpcStart(final RpcStartEvent event) {
+    onRpcStart();
+  }
+
+  public void onRpcStart() {
     if (++activeCalls == 1) {
       if (hideDepth == 0) {
         loading.setVisible(true);
@@ -65,6 +69,10 @@ public class RpcStatus implements RpcStartHandler, RpcCompleteHandler {
 
   @Override
   public void onRpcComplete(final RpcCompleteEvent event) {
+    onRpcComplete();
+  }
+
+  public void onRpcComplete() {
     if (--activeCalls == 0) {
       loading.setVisible(false);
     }
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/NativeList.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/NativeList.java
new file mode 100644
index 0000000000..e820fe060f
--- /dev/null
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/NativeList.java
@@ -0,0 +1,55 @@
+// Copyright (C) 2012 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.client.rpc;
+
+import com.google.gwt.core.client.JavaScriptObject;
+
+import java.util.AbstractList;
+import java.util.List;
+
+/** A read-only list of native JavaScript objects stored in a JSON array. */
+public class NativeList<T extends JavaScriptObject> extends JavaScriptObject {
+  protected NativeList() {
+  }
+
+  public final List<T> asList() {
+    return new AbstractList<T>() {
+      @Override
+      public T set(int index, T element) {
+        T old = NativeList.this.get(index);
+        NativeList.this.set0(index, element);
+        return old;
+      }
+
+      @Override
+      public T get(int index) {
+        return NativeList.this.get(index);
+      }
+
+      @Override
+      public int size() {
+        return NativeList.this.size();
+      }
+    };
+  }
+
+  public final boolean isEmpty() {
+    return size() == 0;
+  }
+
+  public final native int size() /*-{ return this.length; }-*/;
+  public final native T get(int i) /*-{ return this[i]; }-*/;
+  private final native void set0(int i, T v) /*-{ this[i] = v; }-*/;
+}
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/NativeMap.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/NativeMap.java
new file mode 100644
index 0000000000..cde9041bc0
--- /dev/null
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/NativeMap.java
@@ -0,0 +1,93 @@
+// Copyright (C) 2012 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.client.rpc;
+
+import com.google.gwt.core.client.JavaScriptObject;
+import com.google.gwtjsonrpc.common.AsyncCallback;
+
+import java.util.Set;
+
+/** A map of native JSON objects, keyed by a string. */
+public class NativeMap<T extends JavaScriptObject> extends JavaScriptObject {
+  /**
+   * Loop through the result map's entries and copy the key strings into the
+   * "name" property of the corresponding child object. This only runs on the
+   * top level map of the result, and requires the children to be JSON objects
+   * and not a JSON primitive (e.g. boolean or string).
+   */
+  public static <T extends JavaScriptObject,
+      M extends NativeMap<T>> AsyncCallback<M> copyKeysIntoChildren(
+      AsyncCallback<M> callback) {
+    return copyKeysIntoChildren("name", callback);
+  }
+
+  /** Loop through the result map and set asProperty on the children. */
+  public static <T extends JavaScriptObject,
+      M extends NativeMap<T>> AsyncCallback<M> copyKeysIntoChildren(
+      final String asProperty, AsyncCallback<M> callback) {
+    return new TransformCallback<M, M>(callback) {
+      @Override
+      protected M transform(M result) {
+        result.copyKeysIntoChildren(asProperty);
+        return result;
+      }
+    };
+  }
+
+  protected NativeMap() {
+  }
+
+  public final Set<String> keySet() {
+    return Natives.keys(this);
+  }
+
+  public final native NativeList<T> values()
+  /*-{
+    var s = this;
+    var v = [];
+    var i = 0;
+    for (var k in s) {
+      if (s.hasOwnProperty(k)) {
+        v[i++] = s[k];
+      }
+    }
+    return v;
+  }-*/;
+
+  public final int size() {
+    return keySet().size();
+  }
+
+  public final boolean isEmpty() {
+    return size() == 0;
+  }
+
+  public final boolean containsKey(String n) {
+    return get(n) != null;
+  }
+
+  public final native T get(String n) /*-{ return this[n]; }-*/;
+
+  public final native void copyKeysIntoChildren(String p)
+  /*-{
+    var s = this;
+    for (var k in s) {
+      if (s.hasOwnProperty(k)) {
+        var c = s[k];
+        c[p] = k;
+      }
+    }
+  }-*/;
+}
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/Natives.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/Natives.java
new file mode 100644
index 0000000000..3d99c9e4a8
--- /dev/null
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/Natives.java
@@ -0,0 +1,56 @@
+// Copyright (C) 2012 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.client.rpc;
+
+import com.google.gwt.core.client.JavaScriptObject;
+import com.google.gwt.json.client.JSONObject;
+
+import java.util.Collections;
+import java.util.Set;
+
+public class Natives {
+  /**
+   * Get the names of defined properties on the object. The returned set
+   * iterates in the native iteration order, which may match the source order.
+   */
+  public static Set<String> keys(JavaScriptObject obj) {
+    if (obj != null) {
+      return new JSONObject(obj).keySet();
+    }
+    return Collections.emptySet();
+  }
+
+  public static <T extends JavaScriptObject> T parseJSON(String json) {
+    if (parser == null) {
+      parser = bestJsonParser();
+    }
+    return parse0(parser, json);
+  }
+
+  private static native <T extends JavaScriptObject>
+  T parse0(JavaScriptObject p, String s)
+  /*-{ return p(s); }-*/;
+
+  private static JavaScriptObject parser;
+  private static native JavaScriptObject bestJsonParser()
+  /*-{
+    if ($wnd.JSON && typeof $wnd.JSON.parse === 'function')
+      return $wnd.JSON.parse;
+    return function(s) { return eval('(' + s + ')'); };
+  }-*/;
+
+  private Natives() {
+  }
+}
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/RestApi.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/RestApi.java
new file mode 100644
index 0000000000..bd6909248e
--- /dev/null
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/RestApi.java
@@ -0,0 +1,174 @@
+// Copyright (C) 2012 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.client.rpc;
+
+import com.google.gerrit.client.RpcStatus;
+import com.google.gwt.core.client.GWT;
+import com.google.gwt.core.client.JavaScriptObject;
+import com.google.gwt.http.client.Request;
+import com.google.gwt.http.client.RequestBuilder;
+import com.google.gwt.http.client.RequestCallback;
+import com.google.gwt.http.client.RequestException;
+import com.google.gwt.http.client.Response;
+import com.google.gwt.http.client.URL;
+import com.google.gwt.user.client.rpc.StatusCodeException;
+import com.google.gwtjsonrpc.client.RemoteJsonException;
+import com.google.gwtjsonrpc.client.ServerUnavailableException;
+import com.google.gwtjsonrpc.common.AsyncCallback;
+import com.google.gwtjsonrpc.common.JsonConstants;
+
+/** Makes a REST API call to the server. */
+public class RestApi {
+  /**
+   * Expected JSON content body prefix that prevents XSSI.
+   * <p>
+   * The server always includes this line as the first line of the response
+   * content body when the response body is formatted as JSON. It gets inserted
+   * by the server to prevent the resource from being imported into another
+   * domain's page using a &lt;script&gt; tag. This line must be removed before
+   * the JSON can be parsed.
+   */
+  private static final String JSON_MAGIC = ")]}'\n";
+
+  private StringBuilder url;
+  private boolean hasQueryParams;
+
+  /**
+   * Initialize a new API call.
+   * <p>
+   * By default the JSON format will be selected by including an HTTP Accept
+   * header in the request.
+   *
+   * @param name URL of the REST resource to access, e.g. {@code "/projects/"}
+   *        to list accessible projects from the server.
+   */
+  public RestApi(String name) {
+    if (name.startsWith("/")) {
+      name = name.substring(1);
+    }
+
+    url = new StringBuilder();
+    url.append(GWT.getHostPageBaseURL());
+    url.append(name);
+  }
+
+  public RestApi addParameter(String name, String value) {
+    return addParameterRaw(name, URL.encodeQueryString(value));
+  }
+
+  public RestApi addParameterTrue(String name) {
+    return addParameterRaw(name, null);
+  }
+
+  public RestApi addParameter(String name, boolean value) {
+    return addParameterRaw(name, value ? "t" : "f");
+  }
+
+  public RestApi addParameter(String name, int value) {
+    return addParameterRaw(name, String.valueOf(value));
+  }
+
+  public RestApi addParameterRaw(String name, String value) {
+    if (hasQueryParams) {
+      url.append("&");
+    } else {
+      url.append("?");
+      hasQueryParams = true;
+    }
+    url.append(name);
+    if (value != null) {
+      url.append("=").append(value);
+    }
+    return this;
+  }
+
+  public <T extends JavaScriptObject> void send(final AsyncCallback<T> cb) {
+    RequestBuilder req = new RequestBuilder(RequestBuilder.GET, url.toString());
+    req.setHeader("Accept", JsonConstants.JSON_TYPE);
+    req.setCallback(new RequestCallback() {
+      @Override
+      public void onResponseReceived(Request req, Response res) {
+        RpcStatus.INSTANCE.onRpcComplete();
+        int status = res.getStatusCode();
+        if (status != 200) {
+          if ((400 <= status && status < 500) && isTextBody(res)) {
+            cb.onFailure(new RemoteJsonException(res.getText(), status, null));
+          } else {
+            cb.onFailure(new StatusCodeException(status, res.getStatusText()));
+          }
+          return;
+        }
+
+        if (!isJsonBody(res)) {
+          cb.onFailure(new RemoteJsonException("Invalid JSON"));
+          return;
+        }
+
+        String json = res.getText();
+        if (!json.startsWith(JSON_MAGIC)) {
+          cb.onFailure(new RemoteJsonException("Invalid JSON"));
+          return;
+        }
+
+        T data;
+        try {
+          data = Natives.parseJSON(json.substring(JSON_MAGIC.length()));
+        } catch (RuntimeException e) {
+          cb.onFailure(new RemoteJsonException("Invalid JSON"));
+          return;
+        }
+
+        cb.onSuccess(data);
+      }
+
+      @Override
+      public void onError(Request req, Throwable err) {
+        RpcStatus.INSTANCE.onRpcComplete();
+        if (err.getMessage().contains("XmlHttpRequest.status")) {
+          cb.onFailure(new ServerUnavailableException());
+        } else {
+          cb.onFailure(err);
+        }
+      }
+    });
+    try {
+      RpcStatus.INSTANCE.onRpcStart();
+      req.send();
+    } catch (RequestException e) {
+      RpcStatus.INSTANCE.onRpcComplete();
+      cb.onFailure(e);
+    }
+  }
+
+  private static boolean isJsonBody(Response res) {
+    return isContentType(res, JsonConstants.JSON_TYPE);
+  }
+
+  private static boolean isTextBody(Response res) {
+    return isContentType(res, "text/plain");
+  }
+
+  private static boolean isContentType(Response res, String want) {
+    String type = res.getHeader("Content-Type");
+    if (type == null) {
+      return false;
+    }
+    int semi = type.indexOf(';');
+    if (semi >= 0) {
+      type = type.substring(0, semi).trim();
+    }
+    return want.equals(type);
+  }
+}
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/TransformCallback.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/TransformCallback.java
new file mode 100644
index 0000000000..2cd22cb4e3
--- /dev/null
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/rpc/TransformCallback.java
@@ -0,0 +1,38 @@
+// Copyright (C) 2012 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.client.rpc;
+
+import com.google.gwtjsonrpc.common.AsyncCallback;
+
+/** Transforms a value and passes it on to another callback. */
+public abstract class TransformCallback<I, O> implements AsyncCallback<I>{
+  private final AsyncCallback<O> callback;
+
+  protected TransformCallback(AsyncCallback<O> callback) {
+    this.callback = callback;
+  }
+
+  @Override
+  public void onSuccess(I result) {
+    callback.onSuccess(transform(result));
+  }
+
+  @Override
+  public void onFailure(Throwable caught) {
+    callback.onFailure(caught);
+  }
+
+  protected abstract O transform(I result);
+}