A component for Apache Isis' Wicket viewer that renders a collection of entities upon a map.
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This component, intended for use with Apache Isis's Wicket viewer, allows an entity or collection of entities to be rendered within a map (using google’s gmap3 API).


The following screenshots show the example app’s usage of the component with some sample fixture data:

010 install fixtures

Parented collection as gmap

The todo item’s collection contains a list of Locatable entities (also todo items); this is indicated through a button to switch the view:

020 gmap button available on parented collection

Clicking the button shows the same entities on a gmap3:

030 view collection in gmap3 next update location

Update location using service

The previous screenshot shows the todo item also provides an "update location" action:

public Gmap3WicketToDoItem updateLocation(
        final String address) {
    final Location location = this.locationLookupService.lookup(address);
    return this;

When invoked:

040 update location invoke

... it updates the location:

050 location updated

Standalone location as gmap

Invoking an action that returns a list of Locatable entities:

060 view all items

... also results in the button to view in a gmap3:

070 gmap button available on standalone collection

... which then renders the items in a map. Note the tooltips:

080 view collection in gmap3

Click through

Clicking on a map marker drills down to the entity:

090 click through to entity

How to run the Demo App

The prerequisite software is:

  • Java JDK 8 (>= Isis 1.9.0) or Java JDK 7 (⇐ Isis 1.8.0)

    • note that the compile source and target remains at JDK 7

  • maven 3 (3.2.x is recommended).

To build the demo app:

git clone https://github.com/isisaddons/isis-wicket-gmap3.git
mvn clean install

To run the demo app:

mvn -pl webapp jetty:run

Then log on using user: sven, password: pass

API & Usage

gmap3 API Key

In order to use the component an API key is required. See the google documentation for instructions as to how to do this; a free key (with quite generous daily limits) can be used.

Configure the key in WEB-INF/viewer_wicket.properties (or WEB-INF/isis.properties):


Rendering objects on a map

Make your entity implement org.isisaddons.wicket.gmap3.applib.Locatable, such that it provides a Location property of type org.isisaddons.wicket.gmap3.applib.Location.

This property will need to be annotated as @javax.jdo.annotations.Persistent.

For example:

import org.isisaddons.wicket.gmap3.cpt.applib.Locatable;
import org.isisaddons.wicket.gmap3.cpt.applib.Location;

public class ToDoItem implements Locatable {
    private Location location;

    @MemberOrder(name="Detail", sequence = "10")
    public Location getLocation() {
        return location;
    public void setLocation(Location location) {
        this.location = location;

You should then find that any collections of entities that have Locatable properties (either returned from an action, or as a parented collection) will be rendered in a map.


By injecting the provided LocationLookupService domain service, you can write an action to lookup Locations.

For example:

public void lookupLocation(
        final String description) {

To use this the LocationLookupService needs to be registered; see below.


Alternatively, the Location can also be specified directly as a string. The format is mmm.mmm;nnn.nnn, where mmm.mmm is the latitude, and nnn.nnn is the longitude


Sometimes the domain object that implements Locatable will be a supporting object such as an Address, belonging to a Customer, say. When the location marker is clicked in the map, we would rather that the UI opens up the Customer rather than the associated Address (in other words, saving a click).

This requirement is supported by providing an implementation of the LocationDereferencingService:

public interface LocationDereferencingService {
	Object dereference(final Object locatable);

for example, one might have:

public class LocationDereferencingServiceForAddress implements LocationDereferencingService {
	public Object dereference(final Object locatable) {
		if (!(locatable instanceof Address)) {
			return null;
		final Address address = (Address) locatable;
		return address.getCustomer();

Note that there can be multiple implementations of this service; the component will check all that are available. The order in which they are checked depends upon the @DomainServiceLayout(menuOrder=…​) attribute.

How to configure/use

You can either use this component "out-of-the-box", or you can fork this repo and extend to your own requirements.


To use "out-of-the-box", add the component to your project’s dom module’s pom.xml:


Check for later releases by searching Maven Central Repo.

If you wish to use this the LocationLookupService, this needs to be registered:


if using AppManifest, then update its getModules() method:

public List<Class<?>> getModules() {
     return Arrays.asList(
  • otherwise, update the isis.properties file:


And if you have integration tests then register the services' package using IsisSystemForTest.Builder#withServicesIn(…​) method.

"Out-of-the-box" (-SNAPSHOT)

If you want to use the current -SNAPSHOT, then the steps are the same as above, except:

  • when updating the classpath, specify the appropriate -SNAPSHOT version:

  • add the repository definition to pick up the most recent snapshot (we use the Cloudbees continuous integration service). We suggest defining the repository in a <profile>:


Forking the repo

If instead you want to extend this component’s functionality, then we recommend that you fork this repo. The repo is structured as follows:

  • pom.xml - parent pom

  • cpt - the component implementation

  • fixture - fixtures, holding sample domain object classes and fixture scripts

  • webapp - demo webapp (see above screenshots)

Only the cpt project is released to Maven central. The versions of the other modules are purposely left at 0.0.1-SNAPSHOT because they are not intended to be released.

Change Log

  • 1.14.0 - released against Isis 1.14.0

  • 1.13.1 - released against Isis 1.13.2, now require an API key. Also uses mavenmixins (to simplify pom.xml configuration) and as a consequence now runs only on JDK 1.8.

  • 1.13.0 - released against Isis 1.13.0

  • 1.12.0 - released against Isis 1.12.0

  • 1.11.0 - released against Isis 1.11.0

  • 1.10.0 - released against Isis 1.10.0; LocationDereferencingService, issues #8 and #9.

  • 1.9.0 - released against Isis 1.9.0

  • 1.8.0 - released against Isis 1.8.0

  • 1.7.0 - released against Isis 1.7.0

  • 1.6.0 - re-released as part of isisaddons, with classes under package org.isisaddons.wicket.gmap3


Copyright 2013~2017 Dan Haywood

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


Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
KIND, either express or implied.  See the License for the
specific language governing permissions and limitations
under the License.


In addition to Apache Isis, this component depends on:

  • org.wicketstuff:wicketstuff-gmap3 (ASL v2.0 License)

Maven deploy notes

Only the cpt module is deployed, and is done so using Sonatype’s OSS support (see user guide).

Release to Sonatype’s Snapshot Repo

To deploy a snapshot, use:

pushd cpt
mvn clean deploy

The artifacts should be available in Sonatype’s Snapshot Repo.

Release an Interim Build

If you have commit access to this project (or a fork of your own) then you can create interim releases using the interim-release.sh script.

The idea is that this will - in a new branch - update the dom/pom.xml with a timestamped version (eg It then pushes the branch (and a tag) to the specified remote.

A CI server such as Jenkins can monitor the branches matching the wildcard origin/interim/* and create a build. These artifacts can then be published to a snapshot repository.

For example:

sh interim-release.sh 1.15.0 origin


  • 1.15.0 is the base release

  • origin is the name of the remote to which you have permissions to write to.

Release to Maven Central

The release.sh script automates the release process. It performs the following:

  • performs a sanity check (mvn clean install -o) that everything builds ok

  • bumps the pom.xml to a specified release version, and tag

  • performs a double check (mvn clean install -o) that everything still builds ok

  • releases the code using mvn clean deploy

  • bumps the pom.xml to a specified release version

For example:

sh release.sh 1.14.0 \
              1.15.0-SNAPSHOT \
              dan@haywood-associates.co.uk \
              "this is not really my passphrase"

where * $1 is the release version * $2 is the snapshot version * $3 is the email of the secret key (~/.gnupg/secring.gpg) to use for signing * $4 is the corresponding passphrase for that secret key.

Other ways of specifying the key and passphrase are available, see the `pgp-maven-plugin’s documentation).

If the script completes successfully, then push changes:

git push origin master && git push origin 1.14.0

If the script fails to complete, then identify the cause, perform a git reset --hard to start over and fix the issue before trying again. Note that in the cpt’s `pom.xml the nexus-staging-maven-plugin has the autoReleaseAfterClose setting set to true (to automatically stage, close and the release the repo). You may want to set this to false if debugging an issue.

According to Sonatype’s guide, it takes about 10 minutes to sync, but up to 2 hours to update search.