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Write custom events that can be used by 3rd party applications

Is it possible to write custom events that can be handled by 3rd party applications?
We have an existing app and we're finding that many people that use the app are using sql triggers to custom-write functionality of their own certain when things happen in our app.
This has led to some instances where our own processes have slowed down due to shoddy 3rd party Triggers that block our app.
I was thinking we could make this easier for 3rd party devs if we could raise events that they could handle in their own services or apps instead of having to use triggers.
That way we'd lose the blocking because we can just fire the event and continue. Also their slowness/potential crashes would happen outside of our process.
A) is this a reasonable approach?
B) Is this possible? Can I scope an event beyond the scope of my app?
EDIT
I have since found other related questions to be of interest:
wcf cross application communication
Interprocess pubsub without network dependency
Listen for events in another application (This seems very close to what I'm after)
I guess I'm looking for the simplest approach but if we wanted to adopt this method across a number of other apps within our company we'd have some further challenges:
We have some older apps in vb6 and delphi - from those I'd just like to be able to listen for their events in my (or 3rd party) newer C# apps or services.
For now, I'll look at:
Managed Spy and http://pubsub.codeplex.com

No, events are only usable by code that's loaded into your own process. If you don't trust these people now, you really don't want to expose yourself to shoddy code that you load into your own process and throws unhandled exceptions that terminate your app. You'll get the phone call, not them. Besides, they'll use such an event to run code that slows down your app.
In general, anything you do with a dbase will run with an entirely unpredictable amount of overhead. Not just because of triggers added by others, the dbase server could simply be bogged down by other work and naturally slow down over time as it stores more and more data. Make sure that doesn't make your app difficult or unpleasant to use, dbase operations typically must run on a worker thread or be done asynchronously with, say, BeginExecuteXxxx(). And make it obvious in your UI that progress is stalled by the dbase server, not by any code that you wrote. Saves you from having to do a lot of explaining.

What you're looking to do is basically to send messages to other processes. For this, you need some sort of IPC mechanism. Since it sounds like you'll have multiple listeners to each message, a mailslot is probably the best way. Unfortunately, .NET doesn't have built-in support for mailslots, so you'll have to use P/Invoke.
If you're looking for a built-in solution, then you could use named pipes, WCF, .NET Remoting, or bare TCP or UDP. With any of these, though, you'll have to loop through all of your listeners and send the message one at a time to each of them, which is not that big of a deal, but maintaining the separate connections is a little more of a hassle.
Note that with WCF and .NET Remoting, you're pretty much limiting your clients to using .NET as well. If your clients might be native or some other platform, then mailslots, named pipes, and TCP/IP are your best bet.

Good remote application logging/monitoring software

I'm sure this has already been done, but Google isn't helping me - I'm getting swamped with answers for similar but different problems:
My boss has asked me to find or build a system that will log uses of our kiosk installations. We build kiosks using java, native c++, c#, python and using things like Unity. We saw another company we worked with using a simple system where a post call with data was logged on a remote site to be checked later. The system allowed the application programmer to decide the contents of the message, and was able to allocate it to either debug or release according to the programmer's wishes.
An example of the log output might be:
[Debug] 28-11-2011 10:10:20 Kiosk1: Pulse
[Debug] 28-11-2011 10:10:25 Kiosk1: Button pressed
[Debug] 28-11-2011 10:10:45 Kiosk1: Widget used
[Debug] 28-11-2011 10:11:20 Kiosk1: Pulse
I looked at log4net/log4j, but that doesn't seem to be compatible with native c++ or python. I'm probably mistaken there :).
Does anyone know of a system that works like this, or that will otherwise be suitable for logging from such diverse languages? If not, I can write my own easily enough. I just don't want to have to support it :)
Regards,
Steve

I'm not sure, but I think what you're looking for is SPLUNK. This can parse almost every log and display it in a unified manner. It can listen to ports, read log files via polling and parses and indexes anything you throw at any point of time.
You can use this to set up you're own multi-language logging server/system. We've been using this and it seamlessly works in our distributed environment.

While writing a specialized logging backend to handle logging both locally and to the network is quite possible, I would advise against it. The reason being that network latency can be to long so it either stops your application, or logging messages can be queued up if using another process/thread to do the actual network pushing.
A much simpler solution is to use little script that is scheduled to run once or a couple of times per day, and that copies the log file(s) to the remote location.

For C++ I highly recommend Poco logging. It allows you to specify the formatting and log level/output using e.g. a properties file.

the python logging library that is included with python is quite similar to log4net, so if you are used to those, the other will be quite easy to understand, but they do not share code (as far as I know)

Use log4j/log4net with a socket appender or log remotely via rsyslog.

You might be interested in something like web beacons. I know it's not exactly what you're asking for, but you ought to think about it for the same reason that web developers do: it's good to know what users are doing.

Is it possible to enumerate the AppDomains in a remote process?

I have seen this question and a number of blog posts related to using mscoree.CorRuntimeHostClass.EnumDomains method to enumerate the AppDomains within the current process, but I'm wondering if there's a way to enumerate the AppDomains within a separate process on the same machine.
I'd like to be able to write a simple console or even WinForms app that could take a process ID and be able to give me some information about the AppDomains within that process. Is this even possible? I assume it is to some degree given that Process Explorer can give you a list of the AppDomains for a .NET process. I just want to know how to accomplish this with C# code.

It is possible, but you would need to use the debugging API to do it. This is broadly similar to the post you link to, but you use different APIs and interfaces. See Publishing Processes in the Debugging API for an overview and links.
In particular, see the CorpubPublish coclass and the ICorPublish interface, then track down through ICorPublish::GetProcess and ICorPublishProcess::EnumAppDomains.

I guess this post 'Enumerating Managed Processes' by Mike Stall should solve the problem.

A method for high-load web site logging to file?

I need to build in click and conversion tracking (more specific and focused than IIS log files) to an existing web site. I am expecting pretty high load. I have investigated using log4net, specifically the FileAppender Class, but the docs explicitly state: "This type is not safe for multithreaded operations."
Can someone suggest a robust approach for a solution for this type of heavy logging? I really like the flexibility log4net would give me. Can I get around the lack of safe multi-threading using lock? Would this introduce performance/contention concerns?

While FileAppender itself may not be safe for logging, I'd certainly expect the normal access routes to it via log4net to be thread-safe.
From the FAQ:
log4net is thread-safe.
In other words, either the main log4net framework does enough locking, or it has a dedicated logging thread servicing a producer/consumer queue of log messages.
Any logging framework which wasn't thread-safe wouldn't survive for long.

You could check out the Logging Application Block available in the Microsoft Enterprise Library. It offers a whole host of different types of loggers, as well as a handy GUI configurator that you can point to your app.config\web.config in order to modify it. So there's not need to sift through the XML yourself.
Here's a link to a nice tutorial on how to get started with it:
http://elegantcode.com/2009/01/20/enterprise-library-logging-101/

I'm also interested in the answer, but I'll tell you what I was told when I tried to find a solution.
An easy way around it would be to use something like an SQL database. If the data you want isn't well suited for that, you could have each page access write it's own log file and then periodically merge the log files.
However, I'm sure there's a better solution.

When using syslog, you won't be having any threading issues. Syslog, sends the loglines using UDP to a logdaemon (could potentially be on the same machine).
Works especially great if you have more running processes/services, since all log lines are aggregated in 1 viewing tool.
if you expect really heavy loads, look at how the guys from facebook do it: http://developers.facebook.com/scribe/ You can use their opensource logtool. I don't think you'll hit their kind of load just yet, so you should be safe for some time to come!
R

In .NET, can I detect system focus events (C#)?

Is it possible to determine when window focus changes at the system level? I'm writing a time-tracking application, and I'd like to be able to listen for application switching (so that I can begin logging time in a given application). I've poked around the Process class for a good hour here, and while I learned quite a few useful things, I didn't find what I was looking for. I suspect I'll need to use hooks, but it's difficult finding clear documentation on the process, let alone documentation specific to what I'm asking.

See SetWindowHooksEx.
Good article, "Windows Hooks in the .NET Framework":
http://msdn.microsoft.com/en-us/magazine/cc188966.aspx