[EAS] Alert origination software CAP/IPAWS data issues

[Sean Donelan]

I'm trying to avoid calling out specific alert origination software 
vendors. Vendors just gets defensive, and resists fixing their 
software. However, there were minor to major issues with CAP messages 
created in 2017 from most alert origination software vendors. The minor 
stuff was nitpicky, while the major stuff would impact alert processing.

Instead I created some brief and generic CAP XML white papers. They should 
be applicable to all alert origination software developers and programmers.

All of these white papers are on https://www.donelan.com/eas

Unicode and UTF-8 encoding issues were common. The Unicode consortium has 
done a lot of work in later Unicode versions. I tried to distill guidance 
based on what I saw in CAP messages into a couple of pages, but Alert 
Origination Software vendors should also look at the Unicode documents.

Unicode Constraints Creating CAP Alerts (PDF) [2 pages]

CAP XML data type issues is a bit more challenging because the original 
Oasis Common Alerting Protocol (CAP) specifications were intentionally 
vague. Vague standards are good for committee consensus, but bad for 
implementation and interoperability. Different Alert Origination Software 
vendors intepreted the Oasis CAP standards different ways. And each vendor 
will likely assert their intepretation was correct.

Avoiding vendor specifics, I tried to suggest CAP XML data type guidance 
that wasn't covered by the Oasis specifications and IPAWS profile. These 
are conservative data types for creating CAP message. In other words, CAP 
messages created within these constraints should be acceptable by almost 
any CAP message consumer.

XML Constraints Creating CAP Alerts (PDF) [7 pages]

Finally, some good housekeeping guidance for software which consumes CAP 
messages. Again, Unicode processing is a common issue. It also explains 
the reason for the CAP data type guidance above. The issues aren't as 
noticable with English language CAP messages, typically Windows-1252 
characters such as smart quotes. But issues showed up with some Spanish 
language CAP messages, and were extremely problematic with a CAP message 
using non-latin characters.

Hints Consuming XML CAP Alerts (PDF) [2 pages]

If you have feedback or suggestions, I'd like to hear from you.