User Manual

Table Of Contents
Management services
99-137719-D Confidential - For internal use 7-31
7777
Data interfaces
Note that the client side HTTP implementation may end the connection before the
BGAN XL Radio Module sends back any data. Such a timeout should simply be handled
by resending the request. A typical sequence when waiting for a long time then
becomes:
1. Client sends notification request
2. Client timeout
3. Client re-sends notification request
4. Client timeout
5. Client re-sends notification request
6. BGAN XL Radio Module sends back a HTTP response
7. Client continues processing
To ensure that a write event is detected by the client, the RM HTTP interface employs
an ETag mechanism defined in the HTTP protocol. When reading a parameter or when
a notification event occurs, the RM HTTP protocol generates a tag value and transmits
it along with the response to the client.
The value can be used in a notification request as a way for the client to communicate
the last value (as expressed by the tag) that it has received. The ETag value is included
in the notification request in a "If-None-Match" header field.
If no ETag value is included in the request the BGAN XL Radio Module will wait until
the next write is performed.
The notification timeout can be configured using the sys.sw.http.notification.keepalive
parameter (see 6.4.14 on page 6-19).
Figure 7-3: Notification sequence
Client / AP
BGAN XL Radio
Module
GET request (setting/parameter)
GET reply (value, ETag)
GET request (notification/parameter, ETag)
GET reply (value, ETag)
parameter has
changed since GET
GET reply (value, ETag)
GET request (notification/parameter, ETag)
parameter has not
changed since GET
parameter changed