Data Change Notification

Data change notification (DCN) is an update mechanism that allows an enterprise information system (EIS) to send data changes to SAP Mobile Server over an HTTP or HTTPS connection using JavaScript Object Notation (JSON).

Two steps are required to send DCN all the way from the EIS to the device: EIS to SAP Mobile Server (DCN), and SAP Mobile Server to device (synchronization). DCN is independent of device synchronization and can be used with or without push synchronization.

This guide describes DCN only. For information about Hybrid App DCN (previously called WF-DCN) see the Developer Guide: Hybrid Apps.

All DCN commands support both GET and POST methods. The EIS developer creates and sends a DCN to SAP Mobile Server through HTTP GET or POST operations. The portion of the DCN command parameters that come after http://host:8000/dcn/DCNServlet, can all be in POST; any var=name can be in either the URL (GET) or in the POST. The HTTP POST method is more secure than HTTP GET methods; therefore, SAP recommends that you include the authenticate.password parameter in the POST method, as well as any sensitive data provided for attributes and parameters.

For detailed DCN with payload and without paylod examples using POST commands from a SAP ABAP EIS using a Firefox REST Client, see How-To Use Data Change Notification for CDB Update at http://scn.sap.com/docs/DOC-28185# . While the example is based on SAP Mobile Platform version 2.1, the basic procedures apply to other versions as well.

• Data Change Notification Data Flow
  This diagram illustrates DCN data flow.
• Data Change Notification's Effect on the SAP Mobile Server Cache
  Supported DCN types and their effect on the SAP Mobile Server cache (CDB):
• Data Change Notification With Payload and Without Payload
  Understand the differences between DCN with payload and DCN without payload.
• DCN Payload Compression
  DCN, as well as the REST API, supports compressed HTTP request body and response body using gzip compression, which compresses network traffic and can improve performance for larger payloads where the reduced traffic compensates for the overhead of compression/decompression.
• Related DCN Developer and Administrator Tasks
  DCN is a feature that is performed in different runtime and development components of SAP Mobile Platform. Review the tasks that must be performed by different roles to effectively implement DCN and Hybrid App DCN in an end-to-end environment.
• Implementing Data Change Notification
  Follow the syntax described in this section to implement DCN with payload and DCN without payload.
• Controlling Notifications for Native Applications With Cache Partitions
  SAP Mobile Platform sends out change notifications based on Subscriptions. MBOs are assigned to synchronization groups and when the device application registers for change notifications, they become part of a subscription. Whenever SAP Mobile Platform detects a change in an MBO, it sends out a notification to all subscribers.
• Basic HTTP Authentication
  When you use http://<host>:8000/dcn/DCNServlet, the user authentication is done by SAP Mobile Server extracting the user information from the request parameter.
• Data Change Notification Requirements and Guidelines
  Familiarize yourself with data change notification (DCN) requirements before implementing DCN.
• Data Change Notification Results
  Each binding in a data change notification (DCN) request is associated with an ID. The result status of the DCN request is returned in JavaScript Object Notation (JSON) format, and includes a list of IDs followed by a Boolean success field and status message, in case of error.
• Data Change Notification Filters
  Data change notification (DCN) requests need not always be in the format SAP Mobile Server expects.