Google Maps and Google Talk Integration: GoWhere

Introduction

GoWhere is an experimental collaborative mapping tool which combines online mapping and chat technologies.

Two users with chat accounts can plot points, move the map, zoom the map, and change the map type.

This is in the early experimental stages and I'm sure there are many improvements to be made. See "Future" below for a wish-list of future enhancements.

Prerequisites

You'll want these prerequisites to run GoWhere:

• Latest Java2 Standard Edition Runtime, available from here for PC, Linux, or, was available as a System Update for OSX on 4/17/06.
• Two XMMP chat accounts, two people with accounts, etc. These can be GoogleTalk accounts or other "Jabber" accounts that use this technology.

If you intend to build GoWhere for yourself, download the source below.

Please note that when you first run the Java Applet, you must be willing to accept the certificate that pops up in order for GoWhere to run. With good reason, Java places security restrictions on what Applets are not allowed to access on a client machine. For instance, file access and network access are normally not allowed. Typically, software companies get a third party "Certificate Authority" to "sign" the software... i.e., vouch for the integrity of the code in question. An alternative is to self-sign the Java Applet, which I have done here. It's certainly allowed and is done all the time, but understand that it does rather defeat the purpose of having a signer in the first-place. You can read more about signed Applets here.

All code used for GoWhere is under the GNU General Public License. Source code is available below.

Usage

GoWhere's chat window is very simple and it was not my intention to create a full-fledged chat program. (See JBother for a fully fledged Smack-API Java chat program).

Here's basic usage:

• You and another person will need to have chat accounts.
• You need to add your friend to your Roster/Buddy-List using your native program (i.e. GoogleTalk, gaim, etc.) GoWhere's chat pane does not currently have a facility for doing this, though it does rely on your Buddy List to determine who you can chat with.
• Log In to your chat accounts. On the Login tab. If the login is successful, the title will say "logged in". Check with your chat provider for the proper settings. If Service is left blank, the Server setting will be used. Note that if you need to use a SSL connection, see the Options Tab. Google Talk settings are as follows (subject to change):
  • Screen Name: your GMail user name
  • Password: your GMail password
  • Server: talk.google.com
  • Port: 5222
  • Service: gmail.com
  • (no SSL connection is necessary)
• Switch to the "Chat" tab. You need to select a user to chat with by RIGHT-CLICKING (OSX ctrl-click) on the compose-area (bottom area) of the chat pane. Currently, only a single (non-group) conversation is possible. The title of the compose area will change once a user is selected.
• Now, two users should be able to hold a chat text session. Type in the compose area, hit "Send" or the return key. This is very bare-bones chat client, so no bells and whistles here! ;)
• To begin collaborating using the map, you must check the "Allow modification of my map" box in order to allow your buddy to change YOUR map. (He will need to do the same if you are to change his)
• Map actions are now linked. If your buddy has clicked to "Allow modification of my map" box, you will be able to:
  • Single-Click on your map to add map points. Points you add are colored green, points added by your chat buddy are red.
  • Drag or zoom the map to change the location
  • Change the type of map
  • Push the "Sync" button to send all of your settings to your chat buddy. WARNING: THIS will reset his map and erase any points he has added
• For more advanced users, note that there is a debug tab that is hidden by default (See Options tab). The chat client may be run in stand-alone mode too. This is without any maps of course, but it is useful for testing.

How It Works

The mapping function is implemented thanks to the Google Maps API and is written using JavaScript callbacks. The chat function uses the excellent Java XMMP API, Smack, from JiveSoftware. Events on the map are tied to callbacks in JavaScript. These callbacks call Java functions which build and send custom XMMP Extension messages to trigger remote map events. On the receiving side, the custom XMMP message is received, parsed, and JavaScript callbacks manipulated the Google Maps API accordingly.

Code

The source code may be downloaded as a bzip2 tar archive here.

Future

There is certainly room for future improvements and bug fixes. Here are some ideas, not necessarily in order:

• Add group-chat functionality to the system
• Correct lost marker bug.. it seems that at times, particularly after using the Sync function, some marker overlays become detached from the map and don't change with zoom, map pans, clears, etc.. I'm not sure why this is, but more investigation is needed.
• It's also true that some map events, particularly the zoom change or type change don't trigger their callbacks, particularly after some time. It seems like it might be a Google Maps bug, I see this JavaScript error instead of my callback being called:
  

  Error: e has no properties
  Source File: http://maps.google.com/mapfiles/maps2.50a.api.js
  Line: 471
  

• GUI improvements:
  • Use color markers more effectively, i.e. colorize user in the same way that the marker is colorized
  • Improve look and feel of GUI, which now uses Swing default look and feel
• Improve class hierarchy and modularity
• Write custom XMMP extension code rather than use Smack's simple DefaultExtension

Contact

Questions, comments: j c o o l e y (at) m e d i a (dot) m i t (dot) e d u
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