Passbook update tag: if-modified-since (null) - passbook

Question

I am using Restlet2.0 (java) to build passbook server. When I send a Push Notification to APNs with PushToken, I got message 'if-modified-since (null)' from the server log:
entity.getText() : {"logs":["[2013-03-31 00:18:29 +1100] Get pass task
(pass type pass.xxxxxx.freehug, serial number ABC, if-modified-since
(null); with web service url
http://192.168.1.43:8080/passbook/restlet) encountered error:
Server response was malformed (Missing response data)"]}
This responding URL matches the router defined for the LoggingResource class (Line 4), but not the SerialNumbersPassWithDeviceResource class (Line 2) which defines the passUpdatedSince={tag} parameter to be captured for the latest pkpass comparison:
router.attach("/v1/devices/{deviceLibraryIdentifier}/registrations/{passTypeIdentifier}/{serialNumber}", DeviceRegistrationResource.class); //1/4. Registration - POST/DELETE
router.attach("/v1/devices/{deviceLibraryIdentifier}/registrations/{passTypeIdentifier}?passUpdatedSince={tag}", SerialNumbersPassWithDeviceResource.class); //2. SerialNumbers - GET
router.attach("/v1/passes/{passTypeIdentifier}/{serialNumber}", LatestVersionPassResource.class); //3. LatestVersion - GET
router.attach("/v1/log", LoggingResource.class); //5. Logging - POST
So where can I set the Update Tag (passUpdatedSince={tag}) and how can I get it under the router in above Line 2? Is my router setup for getting Update tag correct?

Answer 1

The passUpdatedSince={tag} value is set from the last successful response that your web service gave to the requsest:
https://{webServiceURL}/v1/devices/{deviceLibraryIdentifier}/registrations/{passTypeIdentifier}
You set it by providing a key of lastUpdated in the JSON dictionary response to the above request. The value can be anything you like, but the simplest approach would be to use a timestamp.
The if-modified-since value is set by the Last-Modified HTTP header sent with the last .pkpass bundle received matching the passTypeIdentifier and serialNumber. Again, you can choose what value to send in this header.
The specific error that you mention above is not due to either of these. It is caused by your web service not providing a .pkpass bundle in response to the request to:
https://{webServiceURL}/v1/passes/{passTypeIdentifier}/{serialNumber}
You may want to try hooking your device up to Xcode, turning on PassKit logging (Settings -> Developer), then monitoring the device's console log as you send the push. This may give you more detail as to why the device sent the message to your web service log.