Hi

I have multiple processes (writer) running on a linux machine (processes are written in perl, c++, php5 and java) which generate messages

I have one process (reader) (can write in any language depending on choice) which takes a message and transfer to a remote server.

Aim is that writer will write messages which reader must read on a near realtime basis (atmax a minute delay). What approach should i choose for this kind of job.

I am thinking of file based mechanism where each writer write to same file and reader reads the file after a minute keeping track of file size and max data to read in a minute slot. But this has problems like

1. How do i achieve multiple process appending to same file without data loss and without performance impact on writer

2. Performance impact of file writing.

Please suggest me alternate / best approach.

PS: Choice of linux distro should not matter

My first instinct would be to use multiple files, and have the reader poll them each in turn, looking for a timestamp to keep the operations in order. That gets away from corrupting a single file with mulitple writers.

Yes, I gave it a thought .. The approach i came up with multiple files is this

Each process writes to a file with name based on it's pid, ensuring mutual exclution amongst processes. But reading the files is little too complex in this case, because

1. Reader need to maintain ptr to all the open files.
2. Reader must continously poll for any new file created.
3. Reader must maintain multiple recovery log in case of system crash. Recovery log will contain position of reader in each file.

Apart from that .. How will read data will be erased from files ?

I'm back in front of my linux box now, and I thought about it some more. Given that you've got multiple writers, have you considered using pipes?

http://en.wikipedia.org/wiki/Named_pipe

that way you could have the data sit in the pipe until it's read by the reader at which point it's gone. No need for any sort of internal pointers, and if the reader goes offline, the pipe persists until it comes back up.

Writer can be in perl, php, java too ... is it easy to implement pipes for them too.

The only one I'm unsure of is php. I've seen it done in C, C++, Java and Perl, but never in php.