[zeromq-dev] Logging format for sys://log transport

[Oliver Smith]

I would like to pose a question here: who is the target audience the 
sys://log transport?

"syslog" is primarily intended for system administrators. But it seems 
like sys://log is more of a debug trail for programmers.

Among many excellent designs by my predecessor here was our product's 
logging system "dbugLog" which, although a little verbose, has 
continually proven invaluable for diagnosing complex interactions across 
a series of distributed processes.

The format is:

LEVEL [TIMESTAMP SOURCEFILE:LINENO] MESSAGE

The []s are literals, there to help with stripping that information out 
with awk/perl/etc.

E.g.

I [20101116-12:21:13.399.221 zmqSend.cpp:112] Connection opened

We have a normalized convention of beginning "message" with a set of 
key:value pairs that distinguish attributions such as ... which 
"teulIndex" (our internal socket API), which user, etc.

I [20101116-12:21:13.399.221 login.cpp:875] t:2231 p:10502 c:oliver 
login granted

I've now started using zmq to log these messages and altered the format 
a little,

LEVEL|FACILITY|TIMESTAMP|SOURCE:LINE|ATTRIBUTIONS|MESSAGE|[BACKTRACE]

I've worked with a lot of distributed systems in the last ~20 years, but 
it has been a wonderful experience being able to rely so heavily on the 
logs.

The inclusion of __FILENAME__ __LINENO__ in the logs has the convenience 
of tying in nicely with various IDEs which can be coaxed into receiving 
a quick rework of the logs into an errors list and give you a guided 
tour of the program flow... Mmm...

This may be more complex than ZMQ needs, but I wanted to put it out 
there as food for thought.

- Oliver