How to wait for a file to exist with php?

I am using an asynchronous webservice which send me back a Job ID. The full response is then send by the webservice as an XML file (jobId.xml) to my server using a PUT request.

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After issuing the request to th开发者_开发技巧e webservice and getting the jobID, I would like to know what would be the best (most efficient) way to wait until the file is created into the PUT directory of my server?

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I am thinking of a loop of file_exist() with a usleep() between each execution and with a timeout.

But I am sure that there is a better way. Something like a listener...

The file can take less than a second to more than 1 minute to arrive.

Thanks!

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1. You could use inotify to watch for file creations in some directory.

2. Alternatively you could modify your PUT handler to notify your script. For example, you could create a named pipe, read from it (blocking), and modify your PUT handler to write on the pipe one it has written the file

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I didn't understand if you need the php process to remain active (not return and die) or not.

If not, consider using incrontab.
It is like a cronjob but instead of running on preconfigured times, it is run according to file changes. You can configure it to listen to a directory, and when a file finished creating on the filesystem, the incronjob will fire your desired program.

This is a solution for a unix/linux OS. You did not mention your OS.