Instead of “trace” I recommend to use the logging API of the Flex framework. To have the output also on the Console window add the TraceTarget to your main application MXML:

<mx:TraceTarget fieldSeparator="->" includeCategory="true" includeLevel="true" includeTime="true" />

The nice thing you get when you add the TraceTarget is that the internal logs of the Flex framework also show up. If you use for instance HTTPService and load something this shows up in your console:

“[SWF] Users:soenkerohde:Documents:workspace:Example:bin-debug:Example.swf - 191,465 bytes after decompression
19:23:22.843->[INFO]->mx.messaging.Producer->’54A8E65E-90C9-3D70-66F6-BA1BEE5842F9′ producer set destination to ‘DefaultHTTP’.
19:23:22.956->[INFO]->mx.messaging.Channel->’direct_http_channel’ channel endpoint set to http:
19:23:22.960->[INFO]->mx.messaging.Producer->’54A8E65E-90C9-3D70-66F6-BA1BEE5842F9′ producer sending message ‘33FDE4CB-764A-C757-4FC6-BA1BEECFF0A6′
19:23:22.973->[DEBUG]->mx.messaging.Channel->’direct_http_channel’ channel sending message:
(mx.messaging.messages::HTTPRequestMessage)#0
body = (Object)#1
clientId = (null)
contentType = “application/x-www-form-urlencoded”
destination = “DefaultHTTP”
headers = (Object)#2
httpHeaders = (Object)#3
messageId = “33FDE4CB-764A-C757-4FC6-BA1BEECFF0A6″
method = “GET”
recordHeaders = false
timestamp = 0
timeToLive = 0
url = “http://feeds.feedburner.com/soenkerohde?format=xml”
19:23:22.978->[INFO]->mx.messaging.Producer->’54A8E65E-90C9-3D70-66F6-BA1BEE5842F9′ producer connected.
19:23:23.002->[INFO]->mx.messaging.Producer->’54A8E65E-90C9-3D70-66F6-BA1BEE5842F9′ producer acknowledge of ‘33FDE4CB-764A-C757-4FC6-BA1BEECFF0A6′.
19:23:23.006->[INFO]->mx.rpc.http.HTTPService->Decoding HTTPService response
19:23:23.011->[DEBUG]->mx.rpc.http.HTTPService->Processing HTTPService response message:
(mx.messaging.messages::AcknowledgeMessage)#0
body = “… REMOVED THE CONTENT HERE”
clientId = “DirectHTTPChannel0″
correlationId = “33FDE4CB-764A-C757-4FC6-BA1BEECFF0A6″
destination = “”
headers = (Object)#1
messageId = “6AF8650F-3634-FD0D-FF23-BA1BEEFFCDDB”
timestamp = 0
timeToLive = 0″

As you see this a bunch of information and the brackets in front indicate the level of the logging message which are DEBUG and INFO here. If you are not interested in DEBUG logs at all simply change the level in the TraceTarget to LogEventLevel.INFO.

What you need to log on your own is pretty simple. Just add this to every class (MXML/AS) to define your logger constant:

import mx.logging.Log;
import mx.logging.ILogger;
private static const logger:ILogger = Log.getLogger("MyCategory");

Now you can use the constant like:

logger.info("this is an info message");

which shows up as: 19:51:47.917->[INFO]->MyCategory->this is an info message
Replace “MyCategory” with a category name. I always use the name of the class. In this case an info message is used but there is also debug, warn, error and fatal to represent the kind of your log message.

4 Responses to 'Stop tracing and start logging'

1. trace(chris.foster) » Sönke Rohde » Stop tracing and start logging - May 6th, 2008 at 4:40 am

   [...] Sönke Rohde » Stop tracing and start logging [...]

2. The Secret to Debugging . . . - May 6th, 2008 at 6:47 pm

   [...] Stop tracing and start logging - Debug information with the good old “trace” is around since ActionScript 1 and has been heavily used as this was a key for debugging a Flash application. In AS3 trace has lost its importance as Flash Player 9 supports Runtime Exceptions … [...]

3. sectore - May 13th, 2008 at 7:42 pm

   Moin Sönke,

   give ThunderBolt AS3 also a try, which is a lightweight logger extension for using Firebug. It supports the Flex Logging API using an own target called “ThunderBoltTarget” as well.

   -Jens
   –
   http://www.websector.de/blog/

4. Sönke Rohde » SOS Logging Target - August 27th, 2008 at 6:41 pm

   [...] I have posted a little extension for SOS about two years ago and now I made a little update which is easier to use. It works the same way as the TraceTarget I already blogged about. [...]

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