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http://issues.apache.org/bugzilla/show_bug.cgi?id=32618 ------- Additional Comments From [EMAIL PROTECTED] 2004-12-09 23:50 ------- B.2. Fix fragile configuration problems. This area is more discussion, and less is currently represented in any proposed interface/class changes. Two things can/should be done here: a. tighten the 'discovery' process to minimize "non-deterministic behavior". b. give *serious* consideration to how we package commons logging. - Declarative Configuration: Now, regarding 'fragile' configurations, a declarative configuration driven programmatically by the "target framework" into which a component might be installed/executing within would resolve a lot of the problems. In such a solution, we should guard against any multiplicity of such "declarations". Throw exception, something, to if multiple occur in the runtime. - ONE Configuration Even in a dynamic "discovery" process, we should adopt a strategy of allowing only ONE configuration to exist. - In absense of an explicit declaration, if there is only one logger available, use it. - In absense of an explicit declaration, if there are multiple loadable loggers available, then configurable preference list could be consulted. Such a list MUST NOT be packaged with the commons logging distributable. - In presense of an explicit declaration, if that is NOT available, then fall back to a default logger (preference list or simple logger) AND log warning/info. - NO configuration of explicit/default loggers in ANY resource packaged with the logger. - Detailed diagnostics Detailed Internal analysis and dump on error/warning. Explain what has failed, why, and what should be done about it. References to a user guide would be acceptable I think. If there is ANY ambiguity, then WARN or INFO at a minimum. - Improve relationship with ClassLoader hierarchies The parent-first class loader mechanism causes problems with in some situations. Specifically, J2EE environments where applications attempt to use commons logging, AND where the runtime also supports it. The apparent solution is both a more deterministic discovery process for *configuration* data, and a more flexible config model. More deterministic ClassLoader behavior with respect to configuration files: - Force adherence to the parent-first ClassLoader precedence even if the ClassLoaders attempt to circumvent [force deterministic behavior]. - Walk ClassLoader hierarchy from top to bottom, discover and track WHERE resources [config files] are available. - Always defer to configuration found in lowest [closest to app] classloader. - Look for multiple copies of config resource loaded by any *one* classloader, throw a configuration exception or warning w/ fall-back to consistent default behavior in such an event OR warn and fall-back to behavior configured by PARENT classloader. - NO configuration file to be packed with commons-logging.jar Flexible config model: - Allow PARENT config to define a *default* attribute [such as logger] which applies to current classloader, and as a default to any child loader. These attributes are always considered in order of PARENT LAST. - Allow PARENT config to define a *must-use* attribute [such as logger] which forces behavior of child loaders. These attributes are always considered in order of PARENT FIRST, and override a corresponding *default* attribute. - The distinction between *default* and *must-use* to be made by different attribute names. - Repackaging Separate Interface from Implementations. Yes, this means TWO jar files (default). We might produce "utility" jar files that contain an interface with ONE implementation, and config for that implementation. We MUST eliminate packaging/solutions that dynamically adapt to environments were our users loose control of what the logger is doing. - Misc - is there any value in: Being able to query the logger implementation for it's "name"? An "Assert" the application/framework runtime can use to verify that all is as expected? Would be be better to "name" a logger, or a specific configuration? I think naming a configuration would lend better towards a deterministic behavior. -- Configure bugmail: http://issues.apache.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are the assignee for the bug, or are watching the assignee. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
