The reason why Time Machine Preference Pane doesn’t show network drive is likely the Mac Developer’s mantra: keep simple things simple and complex things possible. Novice users, by definition, are inexperienced — they’re likely haven’t gone through the pain of losing data and discounted the value of backups. Thus to not complicate things more and make it easy for most users (especially novices) Time Machine’s preferences only cater for the two common cases:

• Directly-attached external storage (via USB, Firewire, or Thunderbolt).
• Time Capsule or Airport Base Station attached storage.

But with Mac OS X 10.7, Apple have now made more advanced cases possible. As with most advanced stuff, you will need to open up Terminal to do it. The secret? The new tmutil command.

Back to the HOWTO. In order to create a Time Machine backup on a network folder  you need to follow these three steps:

1. Create a HFS+ disk image, preferably sparse disk image, and place the disk image file into its destination folder/server where it will live. It shouldn’t matter whether it is SMB (Windows) or AFP (Mac) shared folder as long as your Mac can write to it.
2. Mount the disk image and use the tmutil command to tell where is it.
3. Tell Time Machine to start the backup process to make sure it works.

Still not clear? Here comes the walkthrough

Creating the Disk Image

1. Open Disk Utility
2. Click on New Image
3. Set a large enough size for the disk image. Ensure that the Format is “Mac OS X Extended (Journaled)” (in other words, this will be HFS+, the  Mac’s native filesystem) and the Image Format is “sparse bundle disk image“.
   

   Time Machine Disk Image Settings

4. You can set Encryption if you want but not necessary. On the other hand, encrypting the disk image is a good idea since you’re going to put it on a network that can potentially be accessed by others.
5. Save the disk image to the shared folder. Alternatively you can save the image locally and then move it to the destination folder on a server.

Tell Time Machine to use the Disk Image

1. Open Finder
2. Navigate to the shared folder which you put the new disk image.
3. Double-click on the disk image to mount it. You should see the new volume in the Finder’s sidebar
4. Open Terminal and enter the following command :
   sudo tmutil setdestination /Volumes/{mounted-disk-image}
   Be sure to replace {mounted-disk-image} with the appropriate name for your new disk image. You will be prompted for your password, this is normal.

Do a Test Backup

1. Click the Time Machine icon in the Menu Extras area (that’s the upper-right side of the screen) and select “Back Up Now”.
2. Wait for 10 minutes or so for Time Machine to do its thing
3. Open Finder, navigate to the mounted disk image, and ensure that Time Machine have created the “Backups.backupdb” folder and there is a folder inside it with the same name as your computer.

So that’s just about it. You can also use this method to save backups to a non-Mac drives, like NTFS drives, if you have the appropriate drivers installed to write to those filesystems (hint: MacFUSE+NTFS-3g or Tuxera’s NTFS driver). For more information on the tmutil command, type man tmutil at the Terminal.

Till next time, you take care.

Related posts:

1. Sandboxing the PubSub framework

The feature was inspired by Monica Rankin’s Twitter Experiment in the University of Texas at Dallas. She found that projecting a Twitter hashtag search result on-screen and letting students tweet that hashtag improves student’s engagement in the discussion. This helped her facilitate a healthy weekly class discussion of a relatively large class (about 90 students).

The following text is the transcript of the video.

➠
Hi, I’m Sasmito and you will see a second preview of Resonate, our new Twitter client for educators.

In this preview you can see how Resonate can help you bring out the backchannel by projecting tweets on an overhead projector.

The idea of projecting tweets to assist class discussion was pioneered by Monica Rankin of University of Texas at Dallas. She found that by encouraging students to tweet about the topic being discussed and displaying them on-screen for everyone to see makes students more engaged and makes the discussion more lively, especially in a large class.

Resonate has a special tweet projection mode that allows you to display a twitter timeline or search result on a large screen. Let’s see how to do this.

➠(show projection screen)

Imagine that this window is your overhead projection. When you connect your iPad to an LCD projector or a television using the appropriate cable, Resonate will display this content on your overhead screen or TV.

➠(switch to iPad)

Now, this is what you will see on your iPad’s screen. From here, you can setup what the projector will show. You can write the headline text and subtitle text to set the overall topic of the discussion.

I’m changing the headings now and you can see that the projection is updated immediately.

You can show any one of your timelines or saved searches. In addition, you can also display a search result in your projection. You can search for a hashtag and let your students tweet the hashtag to get their messages on the screen.

Let’s say that I want the class to discuss about #edchat – I’ll enter the hashtag and let’s see what tweets comes out.

The projection screen is updated real-time, so you don’t need to keep manually refreshing it to display the latest tweets.

You have just seen Resonate’s tweet projection feature. Projecting tweets is pretty handy to augment class discussion when the class has many students.

Resonate is currently in development. If you want to be the first to know when Resonate is ready, just go to ResonateApp.com and enter your e-mail address. Also if you want to be a beta tester and get a free copy, just go to resonateapp.com and remember to tick the beta tester box when you register.

Resonate, the twitter app for educators. Find out more in resonateapp.com

Thanks for watching. Until next time.

Related posts:

1. Resonate Overhead Projection
2. Resonate Update – Episode One
3. Resonate marketing site 2.0

If you already own a copy, there is no need to worry because Fund Watch will continue to work as it is, at least until Fundsupermart changes how they list out fund prices. Be sure to keep a backup of your copy since you may not be able to re-download it once it’s taken off the store.

We plan to take Fund Watch off-sale early next year, primarily because iTunes Connect is still not available due to the holiday  maintenance shutdown and we have some holiday plans for the year-end. It is still available now at the iPhone App Store if you want a copy.

Note that if you’re a Mac user, Fundsupermart Widget is still available (and still free). You can use the widget to monitor Fundsupermart Singapore fund prices from your Mac OS X Dashboard.

Thanks and take care.

Related posts:

1. Fund Watch for iPhone now supports Fundsupermart India
2. Downloading Fundsupermart daily price history
3. Fund Watch for Android

News Anchor is our news reader for the Mac. As a news feed reader, it relies heavily on Apple’s PubSub (Publication Subscription) framework to parse the various news feed formats that are available (mostly RSS or ATOM, but since the standards are a bit lax, various websites tend to provide their content in ever-so-slightly different formats). The application is available both at the Mac App Store and direct-download from us. The Mac App Store version has been sandboxed since release 2.4.4 and its corresponding direct-download version was released at the same time to support the changes in the MAS version. This is so that MAS customers can also use the direct-download version, achieved via a clever licensing scheme first described by Daniel Jalkut.

The challenge around sandboxing an app that uses the PubSub framework primarily stems from the way it uses a shared database file that is shared among all applications. Fortunately, it is not system-wide — every user has her own instance of the file placed in the ~/Library directory. Another issue is that the framework uses some mach ports for inter-process communication, but this was pretty straightforward to solve since it shows immediately as sandbox violation messages in the system log.

File access issues

When you sandbox a Mac application that uses the PubSub framework right off the bat, chances are PubSub framework couldn’t parse any RSS feed that you throw at it. Furthermore you’re likely to see these errors in your console log:

[WARNING] SQL Error: SQLITE_CANTOPEN[14.0]: Database file not found
[WARNING] ***** SQL error opening database: SQLITE_CANTOPEN[14.0]: Database file not found
[WARNING] SQL Error: SQLITE_CANTOPEN[14.0]: Database file not found
[WARNING] SQLite::Exception "SQLITE_CANTOPEN[14.0]: Database file not found" caught in static void PubSub::ClientCore::openClientSession()
[WARNING] std::exception "std::exception" caught in objc_object* -[PSFeed initWithData:URL:](PSFeed*, objc_selector*, NSData*, NSURL*)

These warning messages sounds like the PubSub framework couldn’t find the path to its shared database directory. Why? Because by being in a sandbox, the application gets its own home directory that is several levels down from the user’s own directory. Since the home folder have moved (at least from the application’s point of view) the PubSub Framework then couldn’t locate its database that is normally found in ~/Library/PubSub and simply fail without throwing any exception on to the Objective-C side.

To regain access to the PubSub database, you will need to add read/write access entitlements to your application and add a symbolic link so that the PubSub framework can access it from within your application’s home directory. Adding an entitlement alone is not enough since the application’s view of the home directory have changed and some Unix-trickery is required to locate the file.

File entitlements

Add these read/write entitlements to your application do that it can access PubSub’s database

<key>com.apple.security.temporary-exception.files.home-relative-path.read-write</key>
<array>
    <string>/Library/PubSub/</string>
    <string>/Library/PubSub/Database/</string>
</array>

Symbolic Link

Adding file access entitlements only gives your application the ablility to read/write those files, but doesn’t help much on finding those files. Remember that a sandboxed application has its own home directory that is separated from the user’s normal home directory. Then how the sandboxed application can access shared files? By providing symbolic links from the sandbox to the files real positions.

Apple themselves also do this. When a sandbox directory is initialized, its Library directory is pre-populated with symbolic links of a number of important subdirectories that points to their respective true locations inside the user’s library folder. Take a look at the following sample Library folder in a sandbox:

athena:Library adib$ pwd
/Users/adib/Library/Containers/com.basilsalad.newsanchor/Data/Library
athena:Library adib$ ls -lah
total 176
drwx------  27 adib  adib   918B Nov 12 11:58 .
drwx------  11 adib  adib   374B Nov 12 11:57 ..
-rw-r--r--@  1 adib  adib    12K Nov 12 11:57 .DS_Store
drwx------   5 adib  adib   170B Nov 20 23:31 Application Support
lrwxr-xr-x   1 adib  adib    17B Nov 12 11:57 Audio -> ../../../../Audio
drwx------@  3 adib  adib   102B Nov 12 11:57 Caches
lrwxr-xr-x   1 adib  adib    21B Nov 12 11:57 Calendars -> ../../../../Calendars
lrwxr-xr-x   1 adib  adib    24B Nov 12 11:57 ColorPickers -> ../../../../ColorPickers
lrwxr-xr-x   1 adib  adib    21B Nov 12 11:57 ColorSync -> ../../../../ColorSync
lrwxr-xr-x   1 adib  adib    18B Nov 12 11:57 Colors -> ../../../../Colors
lrwxr-xr-x   1 adib  adib    22B Nov 12 11:57 Components -> ../../../../Components
lrwxr-xr-x   1 adib  adib    24B Nov 12 11:57 Compositions -> ../../../../Compositions
drwxr-xr-x   3 adib  adib   102B Nov 20 23:48 Cookies
lrwxr-xr-x   1 adib  adib    21B Nov 12 11:57 Favorites -> ../../../../Favorites
lrwxr-xr-x   1 adib  adib    27B Nov 12 11:57 FontCollections -> ../../../../FontCollections
lrwxr-xr-x   1 adib  adib    17B Nov 12 11:57 Fonts -> ../../../../Fonts
lrwxr-xr-x   1 adib  adib    25B Nov 12 11:57 Input Methods -> ../../../../Input Methods
lrwxr-xr-x   1 adib  adib    23B Nov 12 11:57 KeyBindings -> ../../../../KeyBindings
lrwxr-xr-x   1 adib  adib    28B Nov 12 11:57 Keyboard Layouts -> ../../../../Keyboard Layouts
lrwxr-xr-x   1 adib  adib    21B Nov 12 11:57 Keychains -> ../../../../Keychains
drwx------   2 adib  adib    68B Nov 12 11:57 Logs
drwx------  24 adib  adib   816B Nov 20 23:35 Preferences
lrwxr-xr-x   1 adib  adib    21B Nov 12 11:57 QuickLook -> ../../../../QuickLook
drwx------   2 adib  adib    68B Nov 20 23:48 Saved Application State
lrwxr-xr-x   1 adib  adib    18B Nov 12 11:57 Sounds -> ../../../../Sounds
lrwxr-xr-x   1 adib  adib    20B Nov 12 11:57 Spelling -> ../../../../Spelling
athena:Library adib$

From the above example, you can see for yourself that these subdirectories are links to their real ones in ~/Library four levels up. Unfortunately adding a directory entitlements for additional subdirectories inside ~/Library does not imply that the necesssary symbolic links will be created for you, at least not as of Mac OS X 10.7.2. You’ll need to create those links yourself via the symlink() function call.

Fortunately for linking to PubSub’s database folder you can use this function that I’ve written originally for News Anchor:

bool BSCreatePubSubSymlink()
{
    NSString* libraryDirectory = [NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES) lastObject];
    NSString* pubSubDirectory = [libraryDirectory stringByAppendingPathComponent:@"PubSub"];
    NSString* pubSubTarget = @"../../../../PubSub";
    NSFileManager* fileManager = [NSFileManager defaultManager];

    BOOL isDirectory  = NO;
    NSString* realPubSubDirectory = [libraryDirectory stringByAppendingPathComponent:pubSubTarget];
    if ([fileManager fileExistsAtPath:realPubSubDirectory isDirectory:&isDirectory]) {
        if (isDirectory) {
            int success = symlink([pubSubTarget UTF8String], [pubSubDirectory UTF8String]);
            if (success != 0) {
                if (errno != EEXIST) {
                    return NO;
                }
            }
        }
    }
    return YES;
}

You should find it easy to adapt the function above to create symbolic links for accessing other shared files inside ~/Library.

Mach Ports

Last but not least you should add IPC exceptions needed by the PubSub framework. You probably saw these sandbox violation messages in the console log the moment you enable sandboxing for your app:

    sandboxd: deny mach-lookup com.apple.pubsub.notification

To solve this, simply add these two exceptions to your application’s entitlements:

<key>com.apple.security.temporary-exception.mach-lookup.local-name</key>
<array>
    <string>com.apple.pubsub.notification</string>
</array>

<key>com.apple.security.temporary-exception.mach-lookup.global-name</key>
<array>
    <string>com.apple.pubsub.ipc</string>
</array>

The first entitlement I found out myself whereas the second security exception for com.apple.pubsub.ipc came from the DTS ticket resolution. Since it came from Apple, it’s probably wise to just include the exception.

Sample Project

You can download the sample project here. This contains the BSCreatePubSubSymlink() function as well as all the entitlements needed to get PubSub ready to parse your news feeds.

So thats about it. Apple may be too rushing to enforce sandboxing to the Mac App Store, with brings up issues such as this one and probably many more that others have experienced. But as Mac devs, especially indie devs, we should band together and do our best for everyone involved in the ecosystem, users and devs alike.

Thanks for reading and until next time…

Related posts:

1. The story behind News Anchor
2. News Anchor 2.0 – Enjoy News Feeds with your breakfast
3. News Anchor 1.0 for Mac OS X Release