© Danny Lee/South China Morning Post, via Getty Images
© Xijing Hospital of the Air Force Medical University, via Xinhua
One of the many fine details in macOS is its built-in support for a content caching service, both as server and client. This can be used for local distribution of macOS and other system updates, App Store updates, Apple media content such as Music and movie purchases, and iCloud content.
This appears to have originated as one of the new services added to Mac OS X Server 10.4 Tiger in April 2005, initially confined to a Software Update server. Apple’s online services were growing rapidly at the time, with the iTunes Store opening in 2003, and the first of its App Stores for iOS launching in 2008. Those were followed by the iCloud service in 2011. To cater for those, Apple added a separate Content Caching server by OS X Server 2 in 2012.
This shows the Software Update service in OS X Server 2 in 2012, with a list of some of the updates it had in its cache at the time.
At that time, a client Mac’s Software Update pane in System Preferences had to be pointed at the local server for that to be used instead of Apple’s. However, that didn’t work with App Store caching, for which the /Library/Preferences/com.apple.SoftwareUpdate.plist file had to be edited manually on each client to add a new property specifying the IP address of the local server.
macOS Server 5 in 2015 extended this further.
Features of the Software Update server then included the ability to limit the server’s bandwidth in its link back to Apple’s servers, and to control local network bandwidth used to transfer updates from the server to clients.
Amazingly, its original documentation is still available online here, and instructions for setting up clients remain here.
The Caching service worked with all content and apps provided by the Mac App and iTunes Stores, which of course included OS X updates, and is explained here. By this time, Macs and iOS devices connected to the local network would automatically find a server when it was running; there was minimal configuration for the server, and none for the clients.
When macOS 10.13 High Sierra was released in 2017, that brought update and content caching services to client Macs, and no longer required macOS Server, which was already in its terminal decline. These were configured in a new Content Caching feature added to the Sharing pane in System Preferences.
In essence, you designated one or more Macs as ‘parents’, to serve their cached content to ‘children’, which can themselves host caching services, to allow tiered setups. Initially, parents also needed to share their internet connection, required a minimum of iOS 10.3 for iOS devices, required a wired Ethernet connection to your router, and couldn’t sleep, so had to be run on mains power.
Although the content caching service has become quite widely used since, it’s never been as popular as it deserves. It remains remarkably simple to set up, as seen in these screenshots from 2020.
Clicking on the Options button let you set the cache location and its size.
Tabs were made available if you held the Option key before clicking the Options button, which then became Advanced Options. That let you set up clients, as well as other servers functioning as peers or parents, on more extensive networks.
These remain essentially the same today in Tahoe.
When Apple changed macOS updates in Big Sur, life became more complicated. When updating Apple silicon Macs, the first GB of macOS updates had to be downloaded direct from Apple’s servers, and it was only after that the remainder of the update could be obtained from a local caching server.
Apple has further extended the types of content that can be cached locally, to include
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softwareupdate;Most recently Rosetta 2, screen savers, wallpaper and AI models have been added to the list. Apple’s reference document is here.
Advanced server configurations are catered for by the command tool AssetCacheManagerUtil which can also provide performance information, and there are two additional tools available, AssetCacheLocatorUtil and AssetCacheTetheratorUtil. On the server, performance information is most readily accessed in Activity Monitor’s Cache view, which provides summary statistics for the local cache.
This includes the total size of data served for the last hour, 24 hours, 7 days, and 30 days. To view those graphically, the time period for the charts at the foot can be changed by using it as a popup menu.
These show what happened on my content caching server during the macOS 11.4 update in 2021, for which almost 30 GB still had to be downloaded from Apple’s servers, while just over 20 GB was served from its cache.
Over the last 20 years or so, Software Update and Content Caching services have been remarkably reliable, but in June 2022 there was a period during which updates to XProtect and XProtect Remediator failed to install correctly when attempted through a content caching server. Apple never explained what the cause of that was, but it was eventually fixed and hasn’t recurred since.
Then, out of the blue, iOS and iPadOS 26 introduced a new feature to identify and test a connected caching server.
To access this, in Settings > Wi-Fi tap the ⓘ button on your current active network, scroll to the bottom and tap Content Caches. Tap the active cache to see full details, together with a download test. Don’t bother looking for an equivalent feature in macOS 26 Tahoe, though, as it isn’t available yet. How odd.
Few other companies have had as much influence on the Mac and its success as Adobe. Founded just over a year before Apple launched the Mac, its original mission was to develop and market its new PostScript page description language, originally designed and written by Adobe’s co-founders, John Warnock (1940-2023) and Charles Geschke (1939-2021). Steve Jobs (1955-2011) was an early enthusiast who shared their vision. After an unsuccessful bid to buy Adobe, Apple bought a 19% stake in it and paid in advance for a five-year licence for PostScript. When Apple introduced its first PostScript laser printer, the LaserWriter, in March 1985 the partnership launched the Desktop Publishing (DTP) revolution.
The same year the LaserWriter brought PostScript and its fonts to the first DTP designers, Adobe started development of its first retail software product, Illustrator, released two years later in 1987. This is a vector graphics editor aimed initially at creating in Encapsulated PostScript Format (EPSF), so had to render the bézier curves of PostScript into the Mac’s QuickDraw graphics.
Illustrator wasn’t offered for Windows for another two years, and even then was widely criticised for lagging behind its Mac version. It wasn’t until 1997 that the Windows version achieved parity. Adobe’s major competitor, Aldus FreeHand, was preferred by many professionals until Adobe bought Macromedia in 2005, following which it was quietly suffocated.
This is Adobe Illustrator running in Mac OS X 10.2 Jaguar in early 2003.
In 1988, Adobe bought the distribution licence to a raster graphics editor already named Photoshop by its original developers, brothers Thomas and John Knoll. The first Adobe version was released for Macs only in February 1990. It has the distinction of being the major app developed using Apple’s MacApp class library, and wasn’t released for Windows until late 1992, by which time it was establishing itself as the standard, particularly for pro photographers. In 2007 it was joined by Adobe Photoshop Lightroom, an image management app that became the standard when Apple discontinued Aperture in 2015.
This is Adobe Photoshop in Mac OS 9.2, in late 2002.
And this is its matching Mac OS X version in 10.2 Jaguar.
Digital non-linear video editing was in its infancy in 1991, when SuperMac Technology developed a QuickTime-based app to support its Video Spigot capture card. Adobe purchased the whole project, and four months later at the end of 1991 released the first version of Adobe Premiere. Although severely constrained by hardware of the time, it proved another successful Mac-only product until its Windows version was released almost two years later, and the product was renamed Adobe Premiere Pro in 2003.
In 1995, Premiere was joined by After Effects following Adobe’s acquisition of Aldus the previous year. After Effects provides digital effects including motion graphics and compositing. In 1999, Apple released Final Cut Pro, whose early development had been by the first Premiere development team working for Macromedia, and has since added Motion and other apps to form its Pro suite. They successfully competed against Adobe’s video products on the Mac.
I have already given a fuller account of the history of PDF and Adobe Acrobat on Macs.
This is Acrobat Distiller 4.0 running on Mac OS 9.1 in early 2001, showing some of its bewildering array of options for turning PostScript files into PDF.
Adobe provided its free Acrobat Reader for Mac OS X, here seen in 10.0 Cheetah.
FrameMaker, originally developed by Frame Technology, is a high-end technical publishing system bought by Adobe in 1995. It was then offered in a premium version with extensive support for SGML, seen here in 2002, two years before Adobe dropped this Mac version.
From its launch in 1985, the leading page layout app for Macs had been Aldus PageMaker, which Adobe acquired when it purchased Aldus in 1994. By this time, PageMaker was under increasing pressure from QuarkXPress, which had become preferred by many professionals. As a result, Aldus had already started to develop what it claimed would be its “Quark killer”, and Adobe continued that. It then discontinued support for PageMaker in a final version released in 2001, which notoriously didn’t support Mac OS X and was never ported to Intel Macs either.
Early development on what was to become Adobe InDesign had started in Aldus before it was swallowed up by Adobe, and its first version was released in 1999, for both Windows and Mac OS. When Mac OS 10.0 Cheetah was released in March 2001, InDesign was its first native page layout app, as well as the first to support Unicode and advanced features of OpenType fonts. As QuarkXPress entered a decline, InDesign became the DTP product of choice.
This is Adobe InDesign in its early days, seen here editing Christmas cards in Mac OS X 10.2 Jaguar in December 2002.
Dreamweaver is a website development app that originated in Macromedia in 1997, and was acquired by Adobe with its purchase of that company in 2005.
Adobe Dreamweaver is seen here running in Mac OS X 10.6 Snow Leopard in August 2009.
Another of Macromedia’s products that Adobe acquired in 2005 was Flash, a rich multimedia software platform that became enormously popular in websites including YouTube and many corporate sites. Flash came with its own scripting language ActionScript, but proved a security nightmare because of its long series of exploited vulnerabilities. Although Flash Player was almost universal on Macs, Apple refused to allow Flash support on its devices, leading to a bitter standoff between Steve Jobs and Adobe. About a year later, much to the relief of security staff around the world, Adobe announced it would cease Flash development; it was deprecated in 2017, and all support stopped at the end of 2020.
‘Shockwave Flash’ and the Flash Player plagued Mac OS X Tiger in 2006.
There have been and still are many other apps from Adobe. One of my favourites was LaserTalk, first released by Emerald City Software in 1988. This was a PostScript debugger acquired by Adobe and bundled in its PostScript SDK. Finally, there was Adobe Streamline, a tool for converting bitmap graphics into Adobe Illustrator vector graphics, first released in 1989, and absorbed into Illustrator in about 2001. No doubt you will also have your own favourites.
Apple sold its 19% stake in Adobe in 1989, and in 2011 Adobe introduced its Creative Cloud subscription service, that two years later replaced its popular Creative Studio DVD distributions with perpetual licences.
