Hi,
I think we have three categories in this area:
1) Monitoring: Listen on the events generated by Tuscany, for example, a
component is started or stopped. (Target for management interfaces)
2) Logging: Produce end-user readable information (info/warning/error) which
is subject to I18N/L10N. (Target for end-users)
3) Tracing: Dump out input/output/exception for method calls for the purpose
of debugging/troubleshooting. (Target for developers/technical support)
IMO, we can cover 2) & 3) using AOP.
AOP-based tracing is obvious. It's simple to define pointcuts to trap all
the methods of interest and dump out the input/output/exception data.
@Pointcut("call(* org.apache.tuscany.sca..*(..))")
Logging is a bit tricky because we will need to know what method calls are
meant to be logging. We could use a Logger (for example,
org.apache.tuscany.sca.logging.Logger or just the pure
java.util.logging.Logger) in the code where logging is desired.
Logger logger = ...; // By default, the logging is no-op
logger.info(msgID, param...); // The code will be instrumented by an aspect
if logging is desired
Then we can create an aspect to trap the following pattern (any logging
calls within the Tuscany code).
@Pointcut("call(* org.apache.tuscany.sca.logging.Logger.*(..))")
Thanks,
Raymond
----- Original Message -----
From: "Jean-Sebastien Delfino" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Cc: "tuscany-user" <[email protected]>
Sent: Friday, August 10, 2007 2:41 PM
Subject: Re: Monitoring, logging and exceptions (again)
Simon Laws wrote:
On 8/8/07, ant elder <[EMAIL PROTECTED]> wrote:
On 8/7/07, Simon Laws <[EMAIL PROTECTED]> wrote:
We talked about this before (
http://www.mail-archive.com/[EMAIL PROTECTED]/msg16784.html)
but
didn't come to any conclusions. So,
1/ What is the requirement?
2/ What is the technical solution?
3/ When should we try and get it done?
To get things going again here are some thoughts drawn from what was
said
in
the referenced thread.
1/ An API in line with accepted logging/management practices to support
arbitrary debugging and runtime info, warning and error logging
A common approach to exception/error handling specifically around
the
detail recorded in the error messages
Internationalization/localization
Execution Tracing
2/ Keeping it simple was a popular sentiment
A number of java logging solutions have been proposed Log4J, SLF4J
etc.
I believe DAS is using Log4J.
We have dependencies that also use logging tools. We can take a
look
at how others approach this, e.g, quick glance at the last CxF release
shows
they include SLF4J jars
Aspects were investigated to show how they can be used for tracing,
seems like an interesting optional facility but adds extra
complexity/dependencies
There was also a suggestion that we could implement some higher
level
tracing, e.g. runtime starts, stops, application loading, component
instance
creation etc.
We need to move error message out of the code and into resource
files
3/ I think we can reasonably expect to agree what approach we are going
to
take fairly quickly and provide some examples, i.e. before the next
release?
People suggested before that we take time out to go through the
code
based and bring it into line. This will take a lot of time but can we
get
it
into 1.0?
Please add your thoughts to the list and we can then draw them
together,
try
some of it out and come to some conclusions.
Simon
+1 for going with SLF4J. If we can decide on this soon then we can all
just
start adding it in to the code we're working on and debugging, and then
maybe have a focused sweep before 1.0 to make sure its in everywhere
useful.
...ant
Cross posting to the user list also as I expect this is close to everyone
heart. Can everyone reply to both lists.
Thanks
Simon
We had a similar discussion in April [1].
Here's what I suggest for logging:
- Separate the trace calls from the runtime code. Insert them
automatically at build time or run time using Aspectj. Raymond on SCA and
Kelvin on SDO already showed how to do it.
- Use SLF4J in these generated trace calls.
[1]
http://mail-archives.apache.org/mod_mbox/ws-tuscany-dev/200704.mbox/[EMAIL
PROTECTED]
Thoughts?
--
Jean-Sebastien
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