How to monitor folders using a service

Question

I wrote a program that can monitor the folders and let me know changes in those folders. But this should run whole the day until the system is ON. This should run as a task in background(like batch process).
I am using Java WatchService for monitoring the folders.
I need some suggestions,

1. How can make this as a service that run in background as a batch process?
2. If i make this as service, will this effect the performance of the system? as there will be files added for every 5mins atleast in the folders.

Please suggest your ideas.

Thanks

Answer 1

You can and it should not effect your system performance when your system have enough resource.

Steps to do that in java

1. Write a small java class FolderMonitor to monitor a particular folder.
   1. Load a Directory File("C:\folder1")
   2. Iterate all the file and hold its last modified time in a Map map key can be a foderName+fileName and value is modified time.
   3. Check with last iteration value, if found modified or new file added do process what you need.
   4. Run the above thru ScheduledExecutorService with required interval
2. Make FolderMonitor class into a jar.

Make it service

1. You can use apache's procrun or tanukisoftware service wrapper for creating a service from java executable jar
   1. Links Java Service wrapper & Apache Procrun

Hope you can do it. All the best

Answer 2

Q> How can make this as a service that run in background as a batch process?
A> See this SO post, it addresses the same question.

Q> If i make this as service, will this effect the performance of the system? as there will be files added for every 5mins atleast in the folders.
A> Because you are using WatchService, this should be really cheap. Quoting the documentation:

Most file system implementations have native support for file change notification. The Watch Service API takes advantage of this support where available. However, when a file system does not support this mechanism, the Watch Service will poll the file system, waiting for events.

If in doubt, you can always monitor your server and see how much CPU and I/O your app uses. I bet this won't be a lot.

Answer 3

Make a thread with an infinite loop, like

while(true) {
   //code and logic
   Thread.sleep(theTimeYouWantBetweenTheScans);
}

Create a .bat file for convinience with stuff, like java -jar myMonitor.jar

The performance depends on your code, but it shouldn't be very heavy. Enjoy.