The log format in access log created by APIX-G and follows Tomcat/ApacheHTTP Server formats.
 

This article provides inputs on customizing the access log created by Facade HTTP/HTTPS Channels in APIX-G.

All supported platforms

Here is a sample for quick reference:

When the value below is set in the asg.properties file:

tibco.clientVar.DefaultImplementation/Connections/HTTP/FacadeHTTPConnection/DebugPattern=%{yyyy MMM dd HH:mm:ss.SSS 'GMT'X}t [%{in_UUID}i] %A %I [%m] '%U' [%s] %bbytes %Dms

and a request with a "in_UUID" header is sent, the following entry can be seen in the access_log file:

2016 Oct 26 11:21:41.891 GMT-05 [abcd1234] 10.97.24.104 HTTP-NIO-Worker-1-1 [GET] '/basichttp/get' [200] 135bytes 639ms

Here is the complete transaction from the engine log:
------------
GET http://vvk-win7-dsktp.na.tibco.com:9222/basichttp/get?param1=value1
in_UUID: abcd1234

 -- response --
200 OK
Date:  Wed, 26 Oct 2016 16:21:41 GMT
Server:  Apache-Coyote/1.1
Content-Type:  text
Content-Length:  135

Received query string is::param1=value1
Received URI is::/basichttp/get?param1=value1
Received payload of size::0
Received payload is::
---------------

Tomcat Documentation.

https://tomcat.apache.org/tomcat-7.0-doc/api/org/apache/catalina/valves/AccessLogValve.html

Apache Documentation.

https://httpd.apache.org/docs/2.4/mod/mod_log_config.html#logformat