Home Forums Mac Software Mac Operating Systems Working on file which lives on another computer

I admit I have not tried this in snowleopard yet, so it may be different. I hope it is.

Under Tiger, in this office, scenario was:

All Macs networked. We're working. It's a publication with 8 pages. The "home" for each issue, if I can put it like that, is A Mac on That Desk.

I want to make a change on a page, so network to that Mac, and on that Mac open the page and make the change. To my HORROR, I then found that the person sitting at that Mac, can and did, open the same page and work on it simultaneously.

I would have thought that my having accessed it over the network, have the page open, would stop anyone else from opening it and editing it. This has caused massive problems in a busy editorial office. As a result we have had to SHOUT OUT LOUD "I've GOT PAGE SIX, OK?" for instance.

1. If I have the page open - over the network, how can anyone else on the 'home' computer open it?

2. Why are there no warnings to the person on the 'home' computer? (e.g., this is open on xyzMac, or this file is in use?)

3. Does this happen under snowleopard? It happened under tiger.


I hope you'all understand this question, but past experience shows that unfortunately you probably won't, quite....... No we can't "lock" the issue we're working on, we're all working on it at once and the work-around is shouting to each other about which page we're working on. Shouldn't be necessary and IIRC wasn't necessary in OS9 !

Thanks.......

this is a "file locking" problem. To my knowledge, os x does not have built-in support for file locking. By "locking" I am not referring to locked or unlocked or other user permissions. This is actually called "file locking" (not a locked file) and means one user opens it with read/write permission, and others can only open with read permission until the lock is removed. Other types of locking can prevent even reading until the changes are made. more advanced locking can notify readers that a change has been completed, and cause or prompt for a reload/update to reflect the changes, or even send a message to readers to reload because some changes have been made, even if the lock remains.

I've seen OS X apps demonstrate locking, for example you can try to open itunes or mail and sometimes get an erroneous lock error saying the file is in use by another user. It's rare but is caused by whatever flag they set when you opened the app, to not get unset when the app was done. (like if it crashed) This is a pseudo-locking, and is at the mercy of app crashes and well-behaving software, it's not OS-driven/enforced and must be managed entirely by the apps and there's no agreed-on standard way to do it on the mac yet.

I've seen MS Word and Excel do file locking, but I don't have a good understanding of the scope, nature, or expected behavior. Appleworks is another app I've seen lock files. Several times I've had to duplicate an appleworks file so I could open it because appleworks insisted it was in use by another app and would only open it read-only. This suggests that appleworks was somehow keeping an inode list of open files to prevent multiple concurrent openings. I think creative suite apps can file lock also, which makes sense given the odds of being in a collaborative environment with that software.

From a practical solution standpoint, there are some hacks you can do for manual locking, but they'll require some user effort and cooperation to pull off. Lets say you have a simple setup with a single folder of ~200 documents you have four people that need to access and make changes to, and are at risk of cross-accessing. Create a folder at the top named " WORKING" (note leading space, puts it at the top by name) Now train your staff to move files into that folder before double clicking them to open them to make changes. When they are done, they must move them back. If another user goes to open a document and can't find it, they can look in WORKING and see if it's there, being worked on. If it lingers there, they can shout out in the cubicle farm "OK who's working on the Customers.xls file?" They'll get an "oops... there you go" from somewhere down the row as someone is reminded to move it back. This is going to happen from time to time. Also occasionally someone will forget to move the file and you could get some cross-editing on it. Don't count this as a failure of the system, it's going to happen infrequently in a non-enforced system. Just keep at it. Get them to quit using the "open recent" option because it can lead to working on files without WORKING them. (set Recent Item history to 0 items or disable it if you can)

It works that way under Every version of OS X up to and including Lion. In fact when someone opens a page that page is literally copied into RAM memory of their computer and so each person is working on their own copy of the page. The surviving version will be whoever saves last.

What you are dealing with is a form of version control and it is something anyone who has multiple persons working on the same file must deal with. Client/Server database systems have elaborate record locking tools to prevent this situation, but that would require you to store the pages in Filemaker or some similar database system. That would require Filemaker Server (that is a separate more expensive product) installed on the main machine and Filemaker installed on all the other computers. (I know your opinion of FIlemaker and its cost so we don't need to rehash that, but that is one of the reasons Filemaker is so pricey.)

I know you just spent a lot of money and time getting your new computers up and running but once before I suggested having a dedicated MacMini running OS X Server could solve this and other problems you have mentioned in the past. The new and improved part of this proposal is using Lion rather than an earlier version of OS X. In Lion there is no Lion Server per se as there was in previous OS X versions. Rather Apple sells a suite of Server applications for Lion through the App Store. This means you only have to buy the particular Server functions you need and you don't have to pay for the whole magilla when you don't need all the bells and whistles. You can also run the MacMini headless so you aren't out the cost of another monitor, keyboard, and mouse. I haven't priced everything out, but I suspect the MacMini with Lion and the appropriate server applications would be cheaper than all the software it would require to solve this issue and almost certainly would be easier to configure and manage.

Another thing to look into in this context is collaborative software or groupware, examples of which are listed here.

It's also entirely possible to have the same file open on the same machine at the same time, via different apps (editing a plist in Property List Editor, TextWrangler, and Terminal for example), or even, with a little AppleScript trickery, to have multiple copies of the same file open in the same application on the same machine at the same time.

This didn't happen in pre-OSX.

I can clearly remember people calling out, for instance, "Why can't I open page three?" and someone else replying "Because I've got it."

That way, no multiple-writes to same document simultaneously could happen.

That OSX allows this to happen is an appalling oversight by the developers, IMO.

(The application in question is Pages, fwiw.)

But that was a software implementation in the program you were using. it wasn't OS 9's doing

There are a number of such collaboration applications available on the market. Virtually all of them work on a client/server model meaning one computer with specialized software acting as the server or central control point and client software on each of the work station computers. With any of these you will be best served with a machine that is dedicated as a server and not used as a work station.

Cost, not counting the server hardware, runs from "free" to big money, and "free" versions are often merely shills to get you to purchase the "premium" modules to make the systems more user friendly. This link to MacUpdate pulls up a list of some 63 collaboration associated applications, some of which may fit your needs. Be careful of cost figures as some of these listings do not include the server software which may be from yet another vendor. CAUTION: There aint no free lunch and any of these will end up costing money and a substantial investment in time to setup and train your users in how to use the system, and I know that is not what you want to hear but it is the truth.

By-the-way, I saw a couple of these systems that I wish I had had when I was developing training material as a member of a team. They would have saved us lots of headaches and no few embarrassments and even a few sleepless weekends recovering from a disaster.

What program are you using?

It is up to individual programs to decide how to deal with simultaneous file access. Adobe Indesign, for example, doesn't let one person open or modify a file if someone else has it open.

That is correct. I don't know what the 3rd party apps do, I assume they hook into the file system to give support to the dumb apps.

Depends on the app. Adobe Indesign writes a "file lock" file in the same directory as the InDesign document being edited; other InDesign instances look for that file. Photoshop opens the file, reads it into memory, then closes it. Someone else can open it; if another person saves it, you'll get a message saying "The original file has changed on disk" when you go to save. Quark opens the file read/write and then holds it open; since the operating system allows only one program to open a file read/write, anyone else who tries to open it gets a "This file is already open" error message. Filemaker does record-level locking; two people can edit the same file at the same time but can't edit the same record at the same time.