This is an open source SDK to create WAP Push in Java.  It implements the PAP 1.0 specification.

WAP Push is based on the traditional client/server model but in contrast to the ordinary pull technology there is no explicit request from the client before the server transmits its content.

A push operation in WAP is accomplished by allowing a Push Initiator (PI) to transmit push content and delivery instructions to a Push Proxy Gateway (PPG), which then delivers the push content to the WAP client according to the delivery instructions. The PPG is typically a WAP Gateway with support for WAP Push. The PI is typically an application that runs on an ordinary web server. It communicates with the PPG using the Push Access Protocol (PAP). The PPG uses the Push Over-the-Air (OTA) Protocol to deliver the push content to the client.

PAP is based on standard Internet protocols. XML is used to express the delivery instructions, and the push content can be any MIME media type.  This SDK supports PAP 1.0 for all the standard operations with the exception of Client Query Capabilities.

PAP 1.0 allows any content type to be pushed to the WAP client. However, the client may not be able to receive them. The WAP standard defines three push content types, which are supported by this SDK:

• Service Indication (SI) ? send a notification to the WAP client.        
• Service Loading (SL) ? cause the WAP client to load and execute a service.        
• Cache Operations (CO) ? invalidate content objects in the WAP client cache.

The WAP Push SDK API is controlled from the WapPushManager class. This is implementation specific and is used to create all other classes as needed. A PI is used to send push messages to ? and receive their corresponding messages from ? a PPG. The interface PushInitiator describes the corresponding class. Results from the PAP 1.0 requests are returned directly as objects by the methods in the PushInitiator class.

The PushMessage class abstracts push messages. This class collects both the control and content parts of the message. The different WAP Push operations are controlled by the control part of the message. Each operation is associated with a separate class.

Result notification from the PPG is in the form of an HTTP POST operation. Providing a URI in the control part of a PushMessage sets up a result notification. The URI is stored together with other options in a SubmitOptions object. Result notification will not occur if the request to the PPG fails in the first place. It will be sent by the PPG to report on the success of the delivery. To handle the result notification a servlet must be set up that waits for the incoming result notification.

This SDK supports the following PAP1.0 operations:

• Push Submission        
• Result Notification        
• Push Cancellation        
• Status Query

With this SDK it is possible to create an application that intensively uses WAP Push to deliver content to mobile devices.  It has been tested in live environments and is very stable. The logging capabilities can be configured at during creation by registering a class that implements the Logger interface. This makes it independent of any type of logging API. The WAP Push SDK API works by passing messages to and from a PPG. This means that it is difficult to test applications without access to a PAP 1.0 compliant system. A sample class is included which, can be used both in scripting and interactive mode to test the Service Indication and Service Loading messages with the Push Submission operation to deliver URLs to a client.