Logging in APIs

Question

When I'm writing an API assembly for someone else to use, it would be useful to have some logging capability to help diagnose the clients' problems using it.

However, if I reference, for example, log4net in my assembly, this might clash with the version of log4net being used by the client's application.

I don't want to reinvent the wheel by writing my own logging framework.

What's the best way to solve my dilemma?

Edit: I suppose I could demand that the particular version of log4net I am using be installed into the GAC to avoid the version clash with the client, but that would make the API a fat thing that requires installation instead of a drop-in assembly.

Answer 1

Use the Enterprise Library. It's flexible enough, and uses both built-in loggers and its own. It has been fairly verison-compatible as well. It's configurable enough that if there were a conflict with a particular component, you could easily swap it out, with just configuration changes.

Answer 2

This is where dependency injection is your friend--you probably don't need to use all of log4net but rather some small bits of it. So write an ILogger class in your app that exposes your functionality, then write an implementation for whatever logger(s) you want to use. For example, a Debug.Trace() logger is great for development or debugging work, while you might need a log4net driver for production. Then use dependency injection, such as StructureMap, to insert the instances of your logger in the production code.

Answer 3

use dependency injection (Unity, Castle Windsor, etc) to specify what the log4net dll to use that way if the client is using an older version, you can just plug in there version of log4net, if they don't have it then provide your own.

Answer 4

Use System.Diagnostics.Trace. No chance of version clashes then!