Web Notification Service (WNS) 2.0.0

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Release v2-00-00

The new OGC best practice paper 06-095 lead to some changes in the design of the WNS, as Ingo Simonis had announced. One of the most obvious change is that the operation 'doCommunication' is no longer used. Instead the operation 'doNotification' is more generally and sends now up to three kinds of messages; the Notification, Communication and Reply message.

The Notification message should be used for one-way-communication and is build from two elements, the payload with the message and the ServiceDescription. The ServiceDescription contains more detailed information about the calling service, even the URL. The Communication message should be used for two-way-communication. This type is more complex than the Notification message and consist of four elements, the already know ServiceDescripition, the as well known payload, the CorrID and the CallbackURL. The CorrID allows the calling service to map the response to an internally request. The CallbackURL says where to response. The Reply message is the response of a Communication message. It consists of the CorrID and the payload.

Another change is that it is now supported to add other MultiUser to already registered MultiUser. In the previous version is was only allowed to add SingleUser to MultiUser. The WNS checks now for upcoming circular dependencies if a MultiUser should be added to MultiUser. It works like this: 1. Check every user of the MultiUser if it is an MultiUser, if so then save the ID into a list, even the own ID. 2. Check the users that should be added to the MultiUser if there is any MultiUser, if so check recursive the associated users if there are MultiUser. If there is a MultiUser compare the ID to those in the list containig the already added MultiUser IDs.

Another feature that was added is a WSDL description of the WNS.

WNS Testing

• 52°North WNS v2-00-00 adapts the OGC 06-095 paper!
• Example page

The feature of sending SMS, Fax and Phone messages will be disabled to prevent message spaming. If you want to test it, get the sources from sourceforge.org or send me an email.

Communication abilities

• The WNS is able to send messages via different protocols, these are HTTP POST, Email, SMS, FAX, PHONE and XMPP, an instant messaging protocoll.
• The Email capabilites contains the support for SSL connections to the SMTP server, the support for TLS and the ability to authenticate before sending.

Message structure

• The message must contain a short description of the fully message, because this short description wil be delivered, if the user has registered to a "lower power" channel, e.g. SMS or Phone.
• Notification type: The user will be informed, but the user must not react on this notification
• Communication type. The user will be informed and should react to this message
• In both, notification and communication type it is now possible to store the message. The user has now the ability to get the full XML message even if the user is just registered to a "lower power" channel, e.g. SMS or Phone.
• To see more details of the message schema use the test site

User administration

• Register SingelUser (a user with an name and messaging channels) or MultiUser (Group of SingleUsers)
• UpdateSingleUserRegistration (edit the name, add or remove channels)
• UpdateMultiUserRegistration (add or remove user)
• Unregister user (delete the user)

WNS Status

• The Web Notification Service was released by 52°North at 10. April 2007.

Download

• Download the 52°North WNS 2.0.0 here.

SVN Structure

• Checkout the WNS from SVN (use viewvc) and build it via Maven (or do the same by importing it into your favorite IDE).

Run the WNS directly from your IDE or deploy it in Tomcat (make sure to configure the WNS appropriately).

Troubleshooting

Some users experienced trouble when installing the WNS. Here is a list of problems that occurred and how to fix them.

WNSConfig cannot be not found

In cases when the servlet cannot find the config.xml file of the WNS (usually contained in WEB-INF/conf folder of the WNS webapp folder) then change the value of the WNS_CONFIG_FILE_LOCATION parameter in the WNS' web.xml to contain the absolute path to the config.xml.