OS X Mavericks

Core Technologies Overview
October 2013

Core Technologies Overview
OS X Mavericks

Contents

Page 4Introduction

Page 5

System Startup
BootROM
EFI
KernelDrivers
Initialization
Address Space Layout Randomization (ASLR)
Compressed Memory
Power Efficiency
App Nap
Timer Coalescing

Page 10

Disk Layout
Partition SchemeCore Storage
File Systems

Page 12

Process Control
Launchd
Loginwindow
Grand Central Dispatch
Sandboxing
GateKeeper
XPC

Page 19

Network Access
Ethernet
Wi-Fi
Multihoming
IPv6
IP over Thunderbolt
Network File Systems
Access Control Lists
Directory Services
Remote Access
BonjourPage 25

Document Lifecycle
Auto Save
Automatic Versions
Document Management
Version Management
iCloud Storage

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Page 28

Data Management
Spotlight
Time Machine

Page 30Developer Tools
Xcode
LLVM
Instruments
Accelerate
Automation
WebKitPage 36

For More Information

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Introduction

With more than 72 million users—consumers, scientists, animators, developers, andsystem administrators—OS X is the most widely used UNIX® desktop operating system.
In addition, OS X is the only UNIX environment that natively runs Microsoft Office,
Adobe Photoshop, and thousands of other consumer applications—all side by sidewith traditional command-line UNIX applications. Tight integration with hardware—from the sleek MacBook Air to the powerful Mac Pro—makes OS X the platform of
choice for an emerging generation of power users.
This document explores the powerful industry standards and breakthrough innovationsin the core technologies that power Apple’s industry-leading user experiences. We walk
you through the entire software stack, from firmware and kernel to iCloud and developer tools, to help you understand the many things OS X does for you every time you
use your Mac.

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System Startup

BootROM
When you turn on the power to a Mac, it activates the BootROM firmware. BootROM,
which is part of the computer’s hardware, has two primary responsibilities: It initializes
system hardware and it selects an operating system to run. Two BootROM components
carry out these functions:• Power-On Self Test (POST) initializes some hardware interfaces and verifies thatsufficient memory is available and in a good state.
• Extensible Firmware Interface (EFI) does basic hardware initialization and selects
which operating system to use.
If multiple OS installations are available, BootROM chooses the one that was last selectedby the Startup Disk System Preference. The user can override this choice by holding
down the Option key while the computer starts up, which causes EFI to display a screen
for choosing the startup volume.

EFI boot picker screen.

EFI
EFI—a standard created by Intel—defines the interface between an operating systemand platform firmware. It supersedes the legacy Basic Input Output System (BIOS) and
OpenFirmware architectures.
Once BootROM is finished and an OS X partition has been selected, control passes tothe boot.efi boot loader, which runs inside EFI. The principal job of this boot loader is toload the kernel environment. As it does this, the boot loader draws the “booting” image
on the screen.
If full-disk encryption is enabled, the boot loader draws the login UI and prompts forthe user’s password, which the system needs so it can access the encrypted disk andboot from it. Otherwise, loginwindow draws the login UI.

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KernelThe OS X kernel is based on FreeBSD and Mach 3.0 and features an extensible architecture based on well-defined kernel programming interfaces (KPIs).
OS X was the first operating system to ship as a single install that could boot intoeither a 32-bit or 64-bit kernel, either of which could run 32-bit and 64-bit applications
at full native performance. OS X now exclusively uses a 64-bit kernel, but it continues
to run both 32-bit and 64-bit applications.
With its 64-bit kernel, OS X is able to address large amounts of physical RAM. OS X
Mavericks has been tested to support up to 128GB of physical RAM on qualified Mac
computers.

Drivers
Drivers in OS X are provided by I/O Kit, a collection of system frameworks, libraries,
tools, and other resources for creating device drivers. I/O Kit is based on an objectoriented programming model implemented in a restricted form of C++ that omits
features unsuitable for use within a multithreaded kernel.
By modeling the hardware connected to an OS X system and abstracting common
functionality for devices in particular categories, the I/O Kit streamlines the process ofdevice-driver development. I/O Kit helps device manufacturers rapidly create drivers
that run safely in a multiprocessing, preemptive, hot-pluggable, power-managed
environment.
To do this, I/O Kit provides the following:• An object-oriented framework implementing common behavior shared among all
drivers and types (families) of drivers• Many families of drivers for developers to build upon
• Threading, communication, and data-management primitives for dealing with issues
related to multiprocessing, task control, and I/O transfers• A robust, efficient match-and-load mechanism that scales well to all bus types• The I/O Registry, a database that tracks instantiated objects (such as driver instances)and provides information about them
• The I/O Catalog, a database of all I/O Kit classes available on a system• A set of device interfaces—plug-in mechanism that allows applications and othersoftware outside the kernel to communicate with drivers• Excellent overall performance• Support for arbitrarily complex layering of client and provider objects

Initialization
There are two phases to system initialization:• Boot refers to loading the bootstrap loader and kernel.
• Root means mounting a partition as the root, or top-level, file system.
Once the kernel and all drivers necessary for booting are loaded, the boot loader
starts the kernel’s initialization procedure. At this point, enough drivers are loaded forthe kernel to find the root device—the disk or network service where the rest of theoperating system resides.

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The kernel initializes the Mach and BSD data structures and then initializes the I/O Kit.
The I/O Kit links the loaded drivers into the kernel, using the device tree to determine
which drivers to link. Once the kernel finds the root device, it roots BSD off of it.

Address Space Layout Randomization (ASLR)
Many malware exploits rely on fixed locations for well-known system functions. To
mitigate that risk, OS X randomly relocates the kernel, kexts, and system frameworks
at system boot. This protection is available to both 32-bit and 64-bit processes.

Compressed Memory
Compressed Memory keeps your Mac fast and responsive by freeing up memory when
you need it most. When your system’s memory begins to fill up, Compressed Memory
automatically compresses the least recently used items in memory, compacting them toabout half their original size. When these items are needed again, they can be instantly
uncompressed.
Compressed Memory improves total system bandwidth and responsiveness, allowing
your Mac to handle large amounts of data more efficiently. Through use of the dictionarybased WKdm algorithm, compression and decompression are faster than reading andwriting to disk. If your Mac needs to swap files on disk, compressed objects are storedin full-size segments, which improves read/write efficiency and reduces wear and tearon SSD and flash drives. The advantages of Compressed Memory include the following:• Shrinks memory usage. Compressed Memory reduces the size of items in memorythat haven’t been used recently by more than 50 percent, freeing memory for theapplications you are currently using.
• Improves power efficiency. Compressed Memory reduces the need to read and write
virtual memory swap files on disk, improving the power efficiency of your Mac.
• Minimizes CPU usage. Compressed Memory is incredibly fast, compressing or decompressing a page of memory in just a few millionths of a second.
• Is multicore aware. Unlike traditional virtual memory, Compressed Memory can run
in parallel on multiple CPU cores, achieving lightning-fast performance for bothreclaiming unused memory and accessing seldom-used objects in memory.

Power Efficiency
The power technologies in OS X Mavericks were built with the capabilities of modern
processors and the demands of modern apps in mind. The new power technologies
work together to achieve substantial power savings, while maintaining—and in somecases even improving—the responsiveness and performance of your Mac.
These technologies are rooted in a few key principles:• Just work for existing apps. No changes to applications should be needed, thoughsmall changes may facilitate additional power savings.
• Keep as many processor cores idle as possible given the demand for CPU.
• When on battery power, only do work that the user is requesting or that is absolutely
essential.

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App Nap
App Nap puts applications that you’re not using into a special low-power state that
regulates their CPU usage as well as network and disk I/O. App Nap can be automatically triggered if an app’s windows are not visible and the app is not playing audio,
though developers can explicitly make an app ineligible for App Nap by using theexisting IOKit IOPMAssertion API (used today in OS X to prevent the system fromsleeping while an app is busy). App Nap triggers a number of power-saving measures,
including:• Timer throttling—Reduces the frequency with which an app’s timers are fired. Thiscan mean significant improvements in CPU idle time when running applications thatfrequently check for data.
• I/O throttling—Assigns the lowest priority to disk or network activity associated witha napping app. The rate at which an application can read or write data from a device
is significantly reduced. In addition, I/O throttling reduces the chances that a background process will interfere with the I/O activity of an app that you are actively using.
• Priority reduction—Reduces the UNIX process priority of an app so that it receives asmaller share of available processor time.

Timer Coalescing
Timer Coalescing minimizes the amount of system maintenance and background workthat is performed while your Mac is running on battery power. Some tasks are set torun on battery power only after a specified amount of time has passed (for example,
Software Update checks every seven days, and can defer checking by up to one day
if the user is on battery power), while other tasks may be configured to never run onbattery power (such as background downloads of software updates).
If allowing the CPU to spend as much time as possible idling is good for power, it
stands to reason that frequently waking up a processor can hurt battery life. Typically,
there are numerous applications and background processes that use timers with different intervals to schedule routine work.
OS X Mountain Lion timers

OS X Mountain Lion timers

125 milliseconds

Typical timer execution sample showing 125 milliseconds on an OS X Mountain Lion systemwith no user interaction. Frequent execution of timers from various processes can prevent theprocessor from idling.

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The challenge becomes: How can the system do all of the required work while
maximizing the amount of time the processor spends at idle? The solution is Timer
Coalescing, which shifts the execution of timers by a small amount so that multiple
applications’ timers are executed at the same time. This can dramatically increase theamount of time that the processor spends idling.
OS OS
X Mavericks
timersX Mavericks timers

125 milliseconds

A sample of the same scenario on OS X Mavericks: 125 milliseconds of timer execution with nouser activity. Executing timers at the same time reduces power use by maximizing processor
idle time.

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Disk Layout

Partition Scheme
Disk drives are divided into logical partitions, which Apple traditionally calls volumes.
Modern Mac systems use the GUID partition table (GPT) partitioning scheme introduced by Intel as part of EFI. The partitioning scheme is formally defined by:• Section 11.2.2 of “Extensible Firmware Interface Specification,” version 1.1, available
from Intel• Chapter 5, “GUID Partition Table (GPT) Format,” of the “Unified Extensible Firmware
Interface Specification,” version 2.0, available from the Unified EFI ForumBy default, the internal hard disk is formatted as GPT. You can explore and modify GPT
disks using the gpt command-line tool derived from FreeBSD. You can also use Apple’s
GPT-aware diskutil utility, which provides more human-readable output.
Helper partitions
Typically, a single partition is “blessed” as the active boot volume via the blesscommand-line tool, though you can also bless specific folders or files. This partition isusually also the root volume.
However, sometimes the boot partition is not the root, such as when the root partitionis encrypted using full-disk encryption or located on a device that requires additional
drivers (such as a RAID array). In that case, a hidden helper partition stores the files
needed to boot, such as the kernel cache. The last three known good helper partitions
are maintained in case one becomes corrupted.
Recovery partitions
New OS X systems include a Recovery HD partition that includes the tools you need to
do the following:• Reinstall OS X
• Repair a hard drive• Restore from a Time Machine backup• Launch Safari to view documentation and search the Internet• Create Recovery HD partitions on external drives
To boot from the Recovery HD partition, restart your Mac while holding down theCommand key and the R key (Command-R). Keep holding them until the Apple icon
appears, indicating that your Mac is starting up. After the Recovery HD finishes startingup, you should see a desktop with an OS X menu bar and an OS X Utilities application
window.
If your Recovery HD is corrupt or unavailable and you have a network connection,
your Mac will automatically use OS X Internet Recovery to download and boot directlyfrom Apple’s servers, using a pristine Recovery HD image that provides all the samefunctionality.

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Core Storage
Layered between the whole-disk partition scheme and the file system used for a
specific partition is a new logical volume format known as Core Storage. Core Storage
makes it easy to dynamically allocate partitions while providing full compatibility withexisting filesystems. In particular, Core Storage allows in-place transformations such as
backgrounding the full-disk encryption used by File Vault 2, intelligent block-level data
migration used by Fusion Drive, ditto blocks for metadata, and copy-on-write B-tree
catalogs.

File Systems
A stackable virtual file system layer allows OS X to dynamically mount, read, and write
to numerous local file systems—including HFS+, UFS, ISO 9660 CD-ROM formats, UDF
for DVDs, FAT32, and NTFS (read only).
Mac OS Extended (HFS+)OS X partitions are usually formatted using some variant of the HFS+ file system. HFS+
supports 64-bit disk space addressing, 32-bit file allocation blocks, journaling, automatic
compression of files, fast B-tree lookups, robust alias support, and rich metadata—
including fine-grained access controls and extended attributes.
The Mac OS Extended file system functionality includes:• Long filenames and international support. HFS+ allows more descriptive filenames,with support for up to 255 characters and Unicode text encoding for internationaland mixed-script filenames.
• Case sensitivity. OS X offers an optional case-sensitive file system format for HFS+,
allowing you to host files for use by UNIX applications that require case sensitivity.
• Large volume support. To accommodate massive databases, image archives, andvideo volumes larger than 16TB, OS X can configure HFS+ volumes to use block sizes
larger than 4K.
• File system journaling. A robust journaling feature protects the integrity of the filesystem in the event of an unplanned shutdown or power failure. With journaling,
the operating system automatically tracks file system operations and maintains acontinuous record of these transactions in a separate file, called a journal. After an
unexpected shutdown, the operating system can use the journal to return the filesystem to a known state—eliminating the need to perform a consistency check on
the entire file system during startup. With a journaled file system, bringing a volume
back online takes just seconds, regardless of the number of files or the size of thevolume.
RAID
OS X supports drive striping (RAID 0) for improved performance, drive mirroring (RAID 1)
for higher reliability, and mirrored striping (RAID 10) for improving both performanceand reliability of storage. In addition, you can reformat storage in the background:
You can promote a single volume to a mirrored volume, split a mirrored array into twovolumes, or rebuild RAID volumes.

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Process Control

Launchd
The kernel invokes launchd as the first process to run and then bootstraps the rest of
the system. It replaces the complex web of init, cron, xinetd, and /etc/rc used
to launch and manage processes on traditional UNIX systems. launchd is available asopen source under the Apache license.
File-based configuration
Each job managed by launchd has its own configuration file in a standard
launchd.plist(5) file format, which specifies the working directory, environment
variables, timeout, Bonjour registration, etc. These plists can be installed independently
in the standard OS X library domains (for example, /Network/Library, /System/Library,/Library, or ~/Library), avoiding the need to edit system-wide configuration scripts. Jobs
and plists can also be manually managed by the launchctl(1) command-line tool.
Launch on demandlaunchd prefers for processes to run only when needed instead of blocking or polling continuously in the background. These launch-on-demand semantics avoid wasting
CPU and memory resources, and thus prolong battery life.
For example, jobs can be started based on the following:• If the network goes up or down
• When a file path exists (for example, for a printer queue)• When a device or file system is mounted
Smart scheduling
Like traditional UNIX cron jobs, launchd jobs can be scheduled for specific calendar
dates with the StartCalendarInterval key, as well as at generic intervals via
the StartInterval key. Unlike cron—which skips job invocations when thecomputer is asleep—launchd starts the job the next time the computer wakes up.
If the computer sleeps through multiple intervals, those events will be coalesced intoa single trigger.
User agentslaunchd defines a daemon as a system-wide service where one instance serves
multiple clients. Conversely, an agent runs once for each user. Daemons should not
attempt to display UI or interact directly with a user’s login session; any and all workthat involves interacting with a user should be done through agents.
Every launchd agent is associated with a Session Type, which determines where it
runs and what it can do, as shown in the following table:
Name

Session type

GUI
Aqua
Non-GUI StandardIO		
Per-user
Background		
Pre-login Loginwindow

Notes
Has access to all GUI services; much like a login item
Runs only in non-GUI login sessions(for example, SSH login sessions)
Runs in a context that’s the parent of all contexts for 		a given user
Runs in the loginwindow context

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Install on demand
To reduce download sizes and the surface area available to attackers, OS X provides
an install-on-demand mechanism for certain subsystems. This provides easy accessfor those users who need them without burdening those who don’t. When you launch
an application that relies on X11 or Java, OS X asks whether you want to download thelatest version as shown in the next image.

OS X prompts users if they attempt to run applications that require X11.

Installing the latest open source software is easier than ever. OS X automatically installs
the compiler and frameworks needed to set up these software packages, or can open
the Mac App Store to download the complete Xcode toolset.

Loginwindow
As the final part of system initialization, launchd launches loginwindow. The
loginwindow program controls several aspects of user sessions and coordinates thedisplay of the login window and the authentication of users.
If a password is set, OS X requires users to authenticate before they can access thesystem. The loginwindow program manages both the visual portion of the login
process (as manifested by the window where users enter name and password
information) and the security portion (which handles user authentication).
Once a user has been authenticated, loginwindow begins setting up the user
environment. As part of this process, it performs the following tasks:• Secures the login session from unauthorized remote access• Records the login in the system’s utmp and utmpx databases• Sets the owner and permissions for the console terminal• Resets the user’s preferences to include global system defaults• Configures the mouse, keyboard, and system sound according to user preferences• Sets the user’s group permissions (gid)• Retrieves the user record from Directory Services and applies that information to
the session• Loads the user’s computing environment (including preferences, environment
variables, device and file permissions, keychain access, and so on)• Launches the Dock, Finder, and SystemUIServer• Launches the login items for the user

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Once the user session is up and running, loginwindow monitors the session and user
applications in the following ways:• Manages the logout, restart, and shutdown procedures• Manages Force Quit by monitoring the currently active applications and responding
to user requests to force quit applications and relaunch the Finder. (Users open thiswindow from the Apple menu or by pressing Command-Option-Escape.)• Arranges for any output written to the standard error console to be logged using
the Apple System Logger (ASL) API. (See “Log Messages Using the ASL API” in the
OS X Developer Library.)

Grand Central Dispatch
Grand Central Dispatch (GCD) supports concurrent computing via an easy-to-use
programming model built on highly efficient system services. This radically simplifies
the code needed for parallel and asynchronous processing across multiple cores.
GCD is built around three core pieces of functionality:• Blocks, a concise syntax for describing work to be done
• Queues, an efficient mechanism for collecting work to be done
• Thread pools, an optimal service for distributing work to be done
These help your Mac make better use of all available CPU cores while improving
responsiveness by preventing the main thread from blocking.
System-wide optimization
The central insight of GCD is shifting the responsibility for managing threads and their
execution from applications to the operating system. As a result, programmers can write
less code to deal with concurrent operations in their applications, and the system canperform more efficiently on both single-processor and multiprocessor machines. Withouta pervasive approach such as GCD, even the best-written application cannot deliver
optimal performance across diverse environments because it lacks insight into everything else happening on the system.
BlocksBlock objects are extensions to C, Objective-C, and C++ that make it easy for programmers
to encapsulate inline code and data for later use. Here’s what a block object looks like:
int scale = 4;
int (^Multiply)(int) = ^(int num) {return scale * num;};
int result = Multiply(7); // result is 28
These types of “closures”—effectively a function pointer plus its invocation context—
are common in dynamically typed interpreted languages, but they were never before
widely available to C programmers. Apple has published both the Blocks Language
Specification and its implementation as open source under the MIT license and added
blocks support to both GCC and Clang/LLVM.

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QueuesGCD dispatch queues are a powerful tool for performing tasks safely and efficiently on
multiple CPUs. Dispatch queues atomically add blocks of code that can execute either
asynchronously or synchronously. Serial queues enable mutually exclusive access toshared data or other resources without the overhead or fragility of locks. Concurrent
queues can execute tasks across multiple distinct threads, based on the number ofcurrently available CPUs.
Thread pools
The root level of GCD is a set of global concurrent queues for every UNIX process,each of which is associated with a pool of threads. GCD dequeues blocks and private
queues from the global queues on a first-in/first-out (FIFO) basis as long as there areavailable threads in the thread pool, providing an easy way to achieve concurrency.
If there is more work than available threads, GCD asks the kernel for more threads,
which are given if there are idle logical processors. Conversely, GCD eventually retires
threads from the pool if they are unused or the system is under excessive load. This all
happens as a side effect of queuing and completing work so that GCD itself doesn’t
require a separate thread. This approach provides optimal thread allocation and CPU
utilization across a wide range of loads.
Event sources
In addition to scheduling blocks directly, GCD makes it easy to run a block in response
to various system events, such as a timer, signal, I/O, or process state change. Whenthe source fires, GCD will schedule the handler block on the specific queue if it is not
currently running, or—more importantly—coalesce pending events if it is running.
This provides excellent responsiveness without the expense of either polling or binding a thread to the event source. Plus, since the handler is never run more than onceat a time, the block doesn’t even need to be reentrant; only one thread will attempt toread or write any local variables.
OpenCL integration
Deeply integrated into OS X, OpenCL accelerates applications by tapping into theparallel computing power of modern GPUs and multicore CPUs. Using a C99-based
language coupled with a flexible API for managing data-parallel workloads, OpenCL
opens up a new range of computationally intensive algorithms for use in yourapplication.
You use OpenCL to transform your apps’ most performance-intensive routines into
computational “kernels.” Each kernel is runtime compiled by OpenCL and efficiently
scheduled for execution, automatically taking best advantage of the parallel processing
capabilities of the targeted GPU or CPU. On OS X, OpenCL kernels can also be run as
blocks using a special GCD queue.

Sandboxing
Sandboxes ensure that processes are only allowed to perform a specific set of expected
operations. For example, a web browser regularly needs to read from the network, butshouldn’t write to the user’s home folder without explicit permission. Conversely, a disk
usage monitor may be allowed to read directories and delete files, but not talk to the
network.
These restrictions limit the damage a program could potentially cause if it became
exploited by an attacker. By using attack mitigation, sandboxes complement the usual
security focus on attack prevention. For this reason, we recommend that sandboxes beused with all applications, and we require their use for apps distributed via the Mac
App Store.

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Mandatory access controls
Sandboxes are built on low-level access control mechanisms enforced in the kernel by
the kauth subsystem. This was introduced in OS X 10.4 based on work originating inTrustedBSD. kauth identifies a valid actor (typically a process) by its credentials.
It then asks one or more listeners to indicate whether that actor can perform a given
action within a specified scope (authorization domain). Only the initial (default) listener
can allow a request; subsequent listeners can only deny or defer. If all listeners defer,kauth denies the request.
Entitlements
Sandboxes collect these low-level actions into specific entitlements that an applicationmust explicitly request by adding the appropriate key to a property list file in its application bundle. Entitlements can control access to:• The entire file system• Specific folders• Networking• iCloud• Hardware (for example, the built-in camera or microphone)• Personal information (for example, contacts)
In addition, entitlements control whether processes inherit their parents’ permissions
and can grant temporary exceptions for sending and receiving events or reading andwriting files.
User intent
While it may seem that virtually all applications would need to request broad entitlements to read and write files, that isn’t the case. OS X tracks user-initiated actions,such as dragging a file onto an application icon, and automatically opens a temporaryhole in the sandbox, allowing the application to read just that one file. In particular,
open and save panels run in a special-purpose PowerBox process that handles all userinteraction. This allows applications to only request entitlements for actions they needto perform autonomously.
Code signing
Entitlements use code signing to ensure the privileges they specify only cover thecode originally intended. Code signing uses public key cryptography to verify that theentity that created the entitlements (that is, the developer) is the same as the authorof the executable in question, and that neither has been modified.

Gatekeeper
Gatekeeper is a feature in OS X that helps protect you from downloading and installing malicious software. Developers can sign their applications, plug-ins, and installer
packages with a Developer ID certificate to let Gatekeeper verify that they come fromidentified developers.
Developer ID certificates
As part of the Mac Developer Program, Apple gives each developer a unique Developer
ID for signing their apps. A developer’s digital signature lets Gatekeeper verify that they
have not distributed malware and that the app hasn’t been tampered with.

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User control
Choose the kinds of apps that are allowed to run on OS X from the following:• Only apps from the Mac App Store, for maximum security• Apps from the Mac App Store as well as apps that have a Developer ID• Apps from anywhere
You can even temporarily override higher-protection settings by clicking on the app
while holding down the Control key and then choosing Open from the contextual
menu. This lets you install and run any app at any time. Gatekeeper ensures that you
stay completely in control of your system.

You control which kinds of apps you want your system to trust.

XPC
XPC leverages launchd, GCD, and sandboxing to provide a lightweight mechanism
for factoring an application into a family of coordinating processes. This factoring
improves launch times, crash resistance, and security by allowing each process tofocus on one specific task.
No configuration needed
XPC executables and xpcservice.plist(5) configuration files are all part of asingle app bundle, so there is no need for an installer.
Launch-on-demand
XPC uses launchd to register and launch helper processes as they are needed.
Asynchronous communication
XPC uses GCD to send and receive messages asynchronously using blocks.

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Privilege separation
XPC processes each have their own sandbox, allowing clean separation of responsibilities. For example, an application that organizes and edits photographs does not usuallyneed network access. However, it can create an XPC helper with different entitlements,
whose sole purpose is to upload photos to a photo-sharing website.
Out-of-band data
In addition to primitive data types such as booleans, strings, arrays, and dictionaries,
XPC can send messages containing out-of-band data such as file descriptors and
IOSurface media objects.

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Network Access

Ethernet
Mac systems were the first mass-market computers to ship with built-in Ethernet. OS X
today supports everything from 10BASE-T to 10 Gigabit Ethernet. The Ethernet capabilities in OS X include the following:
Automatic link detection
Automatic link detection brings up the network stack whenever a cable is plugged in,and safely tears it down when the cable is removed.
Auto-MDIX
This feature reconfigures the connection depending on whether you are connecting toa router or another computer, so you no longer need special crossover cables.
Autonegotiation
Autonegotiaton discovers and uses the appropriate transmission parameters for agiven connection, such as speed and duplex matching.
Channel bonding
Channel bonding supports the IEEE 802.3ad/802.1ax Link Aggregation Control Protocol
for using multiple low-speed physical interfaces as a single high-speed logical interface.
Jumbo framesThis capability uses Ethernet frames of up to 9000 bytes with Gigabit Ethernet switches
that allow them.
TCP segmentation offload
To reduce the work required of the CPU, TCP segmentation offload lets the Network
Interface Card (NIC) handle splitting a large outgoing buffer into individual packets.

Wi-Fi
Apple brought Wi-Fi to the mass market with the original AirPort card and continues
to provide cutting-edge wireless networking across our product lines.
Built into every Mac
Every Mac we ship—from the MacBook Air to the top-of-the-line Mac Pro—has 802.11
networking built right in.
AirDrop
AirDrop makes it easy to safely share files wirelessly with nearby users, even if you
aren’t on the same network. AirDrop leverages the wireless hardware on newer Mac
systems to find and connect to other computers on an ad hoc basis, even if they are
already associated with different Wi-Fi networks.

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Share files wirelessly with anyone around you using AirDrop.

AirPlay
AirPlay lets you stream music throughout your entire house—wirelessly. You canshare audio or mirror your screen from your Mac to an Apple TV or any other AirPlayenabled device.

OS X treats AirPlay as just another audio output device.

Multihoming
OS X can have multiple network interfaces active at the same time, and dynamicallydetermines the optimal one to use for a given connection. Here are some examples ofwhere this is useful:• Connecting to the Internet via Ethernet when you plug a Mac into the network, but
seamlessly switching over to Wi-Fi when the network cable is unplugged.

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21• Routing all corporate traffic through a VPN server for security, while accessing the
public Internet directly to reduce latency.
• Internet sharing, where one interface, such as Ethernet, is connected to the public
Internet while the other, such as Wi-Fi, acts as a router for connecting your otherdevices.

IPv6
OS X provides best-of-breed support for IPv6, the next-generation 128-bit Internet
protocol.
Key features of IPv6 in OS X include:• Full support for both stateful and stateless DHCPv6• Happy Eyeballs algorithm (RFC 6555) for intelligently selecting between IPv6 and IPv4
addresses when both are available• High-level APIs that resolve names directly so applications don’t need to knowwhether they are using IPv4 or IPv6
• IPv6-enabled user applications (for example, Safari)
OS X has passed the U.S. Government v6 Testing Program and conformance tests toensure IPv6 interoperability between computers, mobile devices, and network equipment used within the U.S. Government. USGv6 conformance tests were conducted andvalidated by the ISO/IEC 17025 accredited InterOperability Laboratory at the Universityof New Hampshire.
In addition, Apple has completed a USGv6 SDOC (Supplier’s Declaration of Conformity),
which will be on file with the U.S. Department of Interior.

IP over Thunderbolt
Internet Protocol over Thunderbolt allows you to connect two Mac systems via
Thunderbolt cables for high-speed point-to-point data transfer.

Network File Systems
OS X includes a broad set of network file services—SMB, AFP, and NFS—for sharing
files between Mac and PC.
SMB2
SMB2 is the new default protocol for sharing files in OS X Mavericks. SMB2 is superfast,
increases security, and improves Windows compatibility.
• Efficient. SMB2 features Resource Compounding, allowing multiple requests to besent in a single request. In addition, SMB2 can use large reads and writes to makebetter use of faster networks as well as large MTU support for blazing speeds on
10 Gigabit Ethernet. It aggressively caches file and folder properties and uses opportunistic locking to enable better caching of data. It’s even more reliable, thanks to theability to transparently reconnect to servers in the event of a temporary disconnect.
• Secure. SMB2 supports Extended Authentication Security using Kerberos andNTLMv2.

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22• Compatible. SMB2 is automatically used to share files between two Mac computers
running OS X Mavericks, or when a Windows client running Vista, Windows 7, orWindows 8 connects to your Mac. OS X Mavericks maintains support for AFP and
SMB network file-sharing protocols, automatically selecting the appropriate protocol
as needed.
AFP
The Apple Filing Protocol (AFP) is the traditional network file service used on theMac. Built-in AFP support provides connectivity with older Mac computers and Time
Machine–based backup systems.
NFS
NFS v3 and v4 support in OS X allows for accessing UNIX and Linux desktop and server
systems. With AutoFS, you can now specify automount paths for your entire organization using the same standard automounter maps supported by Linux and Solaris. For
enhanced security, NFS can use Kerberos authentication as an alternative to UNIXUID-based authentication.

Access Control Lists
OS X supports both traditional UNIX file permissions and access control lists (ACLs),
offering administrators an unprecedented level of control over file and folder
permissions.
POSIX permissions
Standard UNIX file permissions, also known as Standard Portable Operating System
Interface (POSIX) permissions, allow you to assign one access privilege to the file’sowner, one to a group, and one to everyone on the network. Multiple users andmultiple groups are not allowed, nor is ownership by a group. The traditional UNIXmodel supports three permissions—read, write, and execute.
Access control lists
For flexibility in complex computing environments, OS X includes file system access
control lists. With file system ACLs, any file object can be assigned multiple users andgroups, including groups within groups. Each file object can also be assigned bothallow and deny permissions, as well as a granular set of permissions for administrative
control, read, write, and delete operations. OS X supports a file permission inheritancemodel, ensuring that user permissions are inherited when files are moved, rewritten,
or copied. ACLs may be set to allow a user to modify a file, but not to delete or evenrename it.

Directory Services
Directory services allow organizations to centralize information about users, groups,
authentication, and computing resources. OS X is designed to be easily integrated
with the most common directory servers including Microsoft Active Directory, OpenDirectory, and standard LDAP-based servers using the RFC 2307 schema standard.
Active Directory integration
OS X integrates with Microsoft Active Directory services. With Active Directory support,
you need only keep a single user record to support OS X systems. Users can accesstheir Mac using the same credentials they would use to access Windows PCs. Mac
systems are fully integrated with Active Directory for password policies, single sign-on,
and directory resources.

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LDAPv3 support
To simplify integration into existing directory services, OS X supports the LDAP RFC
2307 standard. For greater flexibility, OS X supports client-side schema mappings so
attributes in an LDAP-based directory can be easily mapped to settings in OS X.
Single sign-on
OS X uses Kerberos for single sign-on in networks using either Open Directory or
Active Directory. Kerberos uses encryption keys to provide strong authentication
for client/server applications, allowing authorized users to access secure network
services—without exchanging passwords or requiring users to type in their passwords
repeatedly.

Remote Access
Captive networks
Like iOS, OS X automatically detects the presence of a captive network and prompts
for the authentication necessary to reach the public Internet.
VPN client
OS X includes a virtual private network (VPN) client that supports the Internet standard
Layer 2 Tunneling Protocol (L2TP) over IPSec (the secure version of IPv4), as well as theolder Point-to-Point Tunneling Protocol (PPTP). OS X also includes a VPN frameworkthat developers can use to build additional VPN clients.
Firewalls
In addition to the ipfw2-based system-wide firewall, OS X includes an application
firewall that can be configured to allow incoming access to preapproved applications
and services only.
Self-tuning TCP
OS X sets the initial maximum TCP window size according to the local resources andconnection type, enabling TCP to optimize performance when connecting to highbandwidth/high-latency networks.
Port mapping
NAT-PMP enables you to export Internet services from behind a NAT gateway, while
Wide Area Bonjour lets you register the resulting port number with Back to My Mac.
This enables you to easily and securely access your home printer and disk drives
remotely, even from the public Internet.

Bonjour
Bonjour is Apple’s implementation of the Zero Configuration Networking standard. It
helps applications discover shared services such as printers on the local network. It
also enables services to coordinate within and across machines without requiringwell-known port numbers. The ability of Bonjour to painlessly find other computersover a network is critical to many Apple technologies, such as AirPlay and AirDrop.
Link-local addressing
Any user or service on a computer that needs an IP address benefits from this feature
automatically. When your host computer encounters a local network that lacks DHCP
address management, it finds an unused local address and adopts it without you
having to take any action.

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Multicast DNSMulticast DNS (mDNS) uses DNS-format queries over IP multicast to resolve local
names not handled by a central DNS server. Bonjour goes further by handling mDNS
queries for any network service on the host computer. This relieves your application of
the need to interpret and respond to mDNS messages. By registering your service with
the Bonjour mDNSResponder daemon, OS X automatically directs any queries for yourname to your network address.
Service discovery
Service discovery allows applications to find all available instances of a particular
type of service and to maintain a list of named services. The application can thendynamically resolve a named instance of a service to an IP address and port number.
Concentrating on services rather than devices makes the user’s browsing experience
more useful and trouble-free.
Wide-area Bonjour
Bonjour now uses Dynamic DNS Update (RFC 2136) and unicast DNS queries to enablediscovery and publishing of services to a central DNS server. These can be viewed in
the Bonjour tab of Safari in addition to other locations. This feature can be used bycompanies to publicize their intranet or by retailers to advertise promotional websites.
High-level APIsOS X provides multiple APIs for publication, discovery, and resolution of network
services, as follows:• NSNetService and NSNetServiceBrowser classes, part of the Cocoa Foundation framework, provide object-oriented abstractions for service discovery and publication.
• The CFNetServices API declared in the Core Services framework provide Core
Foundation–style types and functions for managing services and service discovery.
• The DNS Service Discovery API, declared in </usr/include/dns_sd.h>,provides low-level BSD socket communication for Bonjour services.
Wake on Demand
Wake on Demand allows your Mac to sleep yet still advertise available services via a
Bonjour Sleep Proxy (typically an AirPort Extreme Base Station) located on your network.
The proxy automatically wakes your machine when clients attempt to access it. Your
Mac can even periodically do a maintenance wake to renew its DHCP address andother leases.
Open source
The complete Bonjour source code is available under the Apache License, Version 2.0,
on Apple’s open source website, where it’s called the mDNSResponder project. You caneasily compile it for a wide range of platforms, including UNIX, Linux, and Windows. We
encourage hardware device manufacturers to embed the open source mDNSResponder
code directly into their products and, optionally, to pass the Bonjour Conformance Test
so they can participate in the Bonjour Logo Licensing Program.

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Document Lifecycle

Auto Save
Thanks to Auto Save, you no longer need to manually save important documents every
few minutes. Applications that support Auto Save automatically save your data in the
background whenever you pause or every five minutes, whichever comes first. If thecurrent state of your document has been saved, OS X won’t even prompt you before
quitting the application, making logouts and reboots virtually painless.

Automatic Versions
Versions automatically records the history of a document as you create and makechanges to it. OS X automatically creates a new version of a document each time you
open it and every hour while you’re working on it. You can also manually create snapshots of a document whenever you like.
OS X uses a sophisticated chunking algorithm to save only the information that haschanged, making efficient use of space on your hard drive (or iCloud). Versions understands many common document formats, so it can chunk documents between logicalsections, not just at a fixed number of bytes. This allows a new version to store—for
example, just the one chapter you rewrote instead of a copy of the entire novel.
OS X automatically manages the version history of a document for you, keeping hourly
versions for a day, daily versions for a month, and weekly versions for all previous
months.
To further safeguard important milestones, OS X automatically locks documents thatwere edited more than two weeks ago. You can change the interval by clicking the
Options button in the Time Machine System Preferences pane, then choosing theinterval you want from the Lock documents pop-up menu.
When you share a document—for example through email, iChat, or AirDrop—only thelatest, final version is sent. All other versions and changes remain safely on your Mac.

Document Management
You can use the pop-up menu next to the document title to edit the document title,tags, location, and lock status.

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Version Management
You can access and browse previous versions of the document using an interface
similar to Time Machine. It shows the current document next to a cascade ofprevious versions, letting you make side-by-side comparisons. You can restore entire
past versions or bring elements from past versions such as pictures or text into yourworking document.

Recovering work from previous versions is just a click away.

iCloud Storage
iCloud Storage APIs enable apps to store documents and key value data in iCloud.
iCloud wirelessly pushes documents to your devices and updates them wheneverthey are changed on any of your devices—automatically.
Ubiquitous storage
The iCloud storage APIs let applications write your documents and data to a central
location and access those items from all your computers and iOS devices. Making a
document ubiquitous using iCloud means you can view or edit those documents fromany device without having to sync or transfer files explicitly. Storing documents in youriCloud account also provides an extra layer of protection. Even if you lose a device,those documents are still available from iCloud storage.
File coordination
Because the file system is shared by all running processes, conflicts can occur when
two processes (or two threads in the same process) try to change the same file at thesame time. To avoid this type of contention, OS X includes support for file coordinators,
which enable developers to safely coordinate file access between different processes
or different threads.
File coordinators mediate changes between applications and the daemon that facilitates the transfer of the document to and from iCloud. In this way, the file coordinator
acts as a locking mechanism for the document, preventing applications and the daemon
from modifying the document simultaneously.

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Safe versions
Versions automatically stores iCloud documents. This means iCloud never asks you toresolve conflicts or decide which version to keep. It automatically chooses the mostrecent version. You can always use the Browse Saved Versions option if you want torevert to a different one. Versions’ chunking mechanism also minimizes the informationthat needs to be sent across the network.
Ubiquitous metadata, lazy content
iCloud immediately updates the metadata (that is, the file name and other attributes)
for every document stored or modified in the cloud. However, iCloud may not push
the actual content to devices until later, perhaps only when actively requested. Devices
always know what’s available but defer loading the data in order to conserve storageand network bandwidth.
Web access
iCloud provides a range of powerful web applications to let you work directly withyour data from a web browser. These include the usual personal information tools(Mail, Calendar, and Address Book) as well as a complete suite of iWork viewers (Pages,
Keynote, and Numbers).

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Data Management

Spotlight
Spotlight is a fast desktop search technology that helps you organize and search forfiles based on either contents or metadata. It’s available to users via the Spotlightwindow in the upper-right of the screen. Developers can embed Spotlight in theirown applications using an API available from Apple.
Standard metadata
Spotlight defines standard metadata attributes that provide a wide range of options forconsistently storing document metadata, making it easier to form consistent queries.
These include POSIX-style file attributes, authoring information, and specialized metadata for audio, video, and image file formats.
Extensible importers
Using OS X Launch Services, Spotlight determines the uniform type identifier of a newor modified file and attempts to find an appropriate importer plug-in. If an importer
exists and is authorized, OS X loads it and passes it the path to the file.
Third parties can create custom importers that extract both standard and custom
metadata for a given file type and return a dictionary that is used to update the
Spotlight datastore.
Dynamic datastore
Every time you create, modify, or delete a file, the kernel notifies the Spotlight engine
that it needs to update the system store. OS X accomplishes this with the highperformance fsevents API.
Live update
Whenever OS X updates the datastore, it also notifies the system results window
and any third-party client applications if the update causes different files to match or
not match the query. This ensures that the Mac always presents the latest real-time
information to the user.

Time MachineTime Machine makes it easy to back up and restore either your entire system orindividual files.
Easy setup
To set up Time Machine, all you need to do is select a local disk or Time Capsule tostore the backups. With OS X, you can select multiple backup destinations for Time
Machine. OS X immediately starts backing up all your files in the background. Afterthe initial backup, it automatically creates new incremental backups every hour.

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Coalescing changes
Time Machine leverages the fsevents technology developed for Spotlight tocontinuously identify and track any folders (what UNIX calls directories) that containmodified files. During the hourly backup, it creates a new folder that appears to represent the entire contents of your hard drive. In reality, it uses a variant of UNIX hard links
that mostly point to trees of unmodified folders already on the disk. Those trees are
effectively copy-on-write, so that future changes never affect the backup version.
Time Machine creates new trees inside a backup for any path that contains modified
folders. Time Machine creates new versions of those folders that contain links to thecurrent files, thus automatically capturing any changes that occurred in the past hour.
This avoids the overhead of either scanning every file on disk or capturing each andevery change to a file.
This technique allows each backup to provide the appearance and functionality of afull backup while only taking up the space of an incremental backup (plus some slightoverhead for the metadata of modified trees). This makes it easy to boot or clone a
system from the most recent Time Machine backup.
Mobile Time Machine
Mobile Time Machine keeps track of modified files even while you are disconnectedfrom your backup drive. When you reconnect, it will automatically record the hourly
snapshots to ensure you don’t lose your version history.
Preserving backups
Time Machine keeps hourly backups for the past 24 hours, daily backups for the pastmonth, and weekly backups until your backup drive is full. At that point, OS X warns
you that it is starting to delete older backups. To be notified whenever OS X deletes anolder backup, open Time Machine preferences, click the Options button, and select thecheckbox next to “Notify after old backups are deleted.”

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Developer Tools

Xcode
Xcode 5 is the latest version of Apple’s integrated development environment (IDE),
a complete toolset for building OS X and iOS applications. The Xcode IDE includes a
powerful source editor, a sophisticated graphical UI editor, and many other features,from highly customizable builds to robust testing infrastructure. Xcode can help you
identify mistakes in both syntax and logic and will even suggest fixes.

￼
The Xcode 5 integrated development environment.

Testing and continuous integration
The Xcode Test Navigator makes it easy to add or edit tests, and execute them one ata time or as a group. The XCTest framework enables you to write tests that run on Mac,
iPhone, iPad, or iOS Simulator, from within Xcode or the command line.
Once you have a test harness created, Xcode can configure a continuous integration“bot” on any Mac in your network running OS X Server. The Xcode bot on the remote
Mac will perform an integration—build, analyze, test, and archive your app—when
anyone on your team commits to source control, or at a defined interval.

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￼
The Xcode Test Navigator.

Static analysis
You can think of static analysis as providing you advanced warnings by identifying
bugs in your code before it is run—hence the term static. The Xcode static analyzer
gives you a much deeper understanding of your code than do traditional compiler
warnings. The static analyzer leverages the Clang code processor to travel downeach possible code path, identifying logical errors such as unreleased memory—wellbeyond the simple syntax errors normally found at compile time.
Fix-itFix-it brings autocorrection from the word processor to your source code. The Xcode
Fix-it feature checks your symbol names and code syntax as you type, highlights any
errors it detects, and even fixes them for you. Fix-it marks syntax errors with a red
underbar or a caret at the position of the error and a symbol in the gutter. Clicking
the symbol displays a message describing the possible syntax error and, in many cases,
offers to repair it automatically.
Source control
Xcode also provides integrated support for Git and Subversion repositories, including
an option to create a local Git repository when you create a new project. Once yourproject is under source control, Xcode provides a special editor, called the version
editor, that compares different versions of files back through time so you can watch
as code changes, and determine who made each change.

LLVM
The next-generation Apple LLVM compiler is based on the open source LLVM.org
project, which employs a unique approach of building compiler technologies as a setof libraries. Capable of working together or independently, these libraries enable rapid
innovation and provide the ability to attack problems never before solved by compilers.
Apple’s compiler, runtime, and graphics teams are extensive contributors to the
LLVM.org community. They use LLVM technology to make Apple platforms faster andmore secure.

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Clang front-end
Clang is a high-performance front-end for parsing C, Objective-C, and C++ code aspart of the Apple LLVM compiler. It supports the latest C++ standards, including full
C++11 support. Clang is also implemented as a series of libraries, allowing its technology to be embedded within the Xcode IDE to enable static code analysis and Fix-it.
Comprehensive optimization
LLVM’s flexible architecture makes it easy to add sophisticated optimizations at any
point during the compilation process. For example, LLVM performs whole-program
analysis and link-time optimizations to eliminate unused code paths.
Automatic Reference Counting
Automatic Reference Counting (ARC) for Objective-C lets the compiler take care ofmemory management. By enabling ARC with the new Apple LLVM compiler, you neverneed to manually track object lifecycles using retain and release, dramaticallysimplifying the development process while reducing crashes and memory leaks. The
compiler has a complete understanding of your objects, and releases each object
the instant it is no longer used. Apps run as fast as ever, with predictable, smooth
performance.

Instruments
Instruments is an application for dynamically tracing and profiling OS X and iOS code.
It is a flexible and powerful tool that lets you track one or more processes, examine
the collected data, and track correlations over time. In this way, Instruments helps you
understand the behavior of both user programs and the operating system.

Instruments in use are on the left, data track in the middle, and extended detail at right.

Synchronized tracks
The Instruments Track pane displays a graphical summary of the data returned by thecurrent instruments. Each instrument has its own track, which provides a chart of thedata collected by that instrument. You use this pane to select specific data points you
want to examine more closely.

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Multiple traces
Each time you click the Record button in a trace document, Instruments starts gathering data for the target processes. Rather than appending the new data to any existing
data, Instruments creates a new trace run to store that data. This makes it easy tocompare behavior between different configurations.
A trace run consists of all of the data gathered between the time you click the Record
button and the Stop button. By default, Instruments displays only the most recent trace
run in the Track pane, but you can view data from previous trace runs in one of two ways:• Use the Time/Run control in the toolbar to select which trace run you want to view.
• Click the disclosure triangle next to an instrument to display the data for all trace runs
for that instrument.
DTraceDTrace is a dynamic tracing facility available for Mac systems. Because DTrace taps into
the operating system kernel, you have access to low-level information about the kernel
itself and about the user processes running on your computer. DTrace is used to power
many of the built-in instruments.
DTrace probes make it easy to use Instruments to create custom instruments. A probe
is a sensor you place in your code that corresponds to a location or event (such as afunction entry point) to which DTrace can bind. When the function executes or the
event is generated, the associated probe fires and DTrace runs whatever actions areassociated with the probe.
Most DTrace actions simply collect data about the operating system and user program
behavior at that moment. It is possible, however, to run custom scripts as part of anaction. Scripts let you use the features of DTrace to fine-tune the data you gather. That
data is then available as an Instruments track to compare with data from other instruments or other trace runs.

Accelerate
Accelerate is a unique framework of hardware-optimized math libraries that provides
the following:• Vector digital signal processing (vDSP). Optimized Fast Fourier Transforms (FFTs),
convolutions, vector arithmetic, and other common video and audio processing tasks
for both single- and double-precision data.
• Vector image processing (vImage). Optimized routines for convolutions, compositing,color correction, and other image-processing tasks, even for gigapixel images.
• vForce. Designed to wring optimal efficiency from modern hardware by specifying
multiple operands at once, allowing only default IEEE-754 exception handling.
• Linear Algebra Package (LAPACK). Industry-standard APIs written on top of BLAS for
solving common linear algebra problems.
• Basic Linear Algebra Subprograms (BLAS) Levels I, II, and III. High-quality “building
block” routines that perform basic vector and matrix operations using standard APIs.
• vMathLib. A vectorized version of libm that provides transcendental operations,enabling you to perform standard math functions on many operands at once.

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Automation
AppleScriptAppleScript is Apple’s native language for application automation, as used by theAppleScript Editor. Its English-like syntax generates Apple events, which use a scripting dictionary (provided by most Mac applications) to programmatically create, edit, ortransform their documents. AppleScript and other Open Scripting Architecture (OSA)
scripts can be activated by contextual menus, user interface elements, Calendar events,and even folder actions, such as drag and drop.
Automator
Automator provides a graphical environment for assembling actions (typically built
from AppleScript or shell scripts) into sophisticated workflows, which can be saved
as either standalone applications or as custom services, print plug-ins, folder actions,
Calendar alarms, and Image Capture plug-ins.
Apple events
The Apple Event Bridge framework provides an elegant way for Cocoa applications(including bridged scripting languages) to generate Apple events based on an application’s dictionary, even generating appropriate header files if necessary.
Services
The Services menu lets you focus on only those actions relevant to your current
selection, whether in the menu bar, the Finder action menu, or a contextual menu.
Individual services can also be disabled and assigned shortcuts from the Keyboard
pane in System Preferences.
iCloud support
iCloud “Documents in the Cloud” support has been added to both the AppleScript
Editor and Automator applications. As with other Apple applications, users can store
their automation documents—including AppleScript scripts, applets, droplets, andAutomator workflow files and applets—to the document storage area provided with
their Apple iCloud accounts. This service ensures that your favorite automation tools
can be easily shared across all of your Apple laptop and desktop computers.
Code signing
Support for code signing has been added as an export feature to both the AppleScript
Editor and Automator applications, enabling Apple developers to easily generate signed
copies of their applets and droplets. Such signed automation applets will not trigger
OS security warnings on computers that are using the default Gatekeeper setting ofallowing only applications downloaded from the Mac App Store and identified developers to execute. This feature is a boon for developers of automation-supporting Mac
applications and for solution providers, allowing them to distribute smooth-launching
automation solutions to their customers and clients.
AppleScript Libraries
AppleScript Libraries provide a new plug-in architecture for extending the power andabilities of AppleScript. AppleScript Libraries are user-created script files and bundles,
written using AppleScript or AppleScript/Objective-C, that can be referenced in scripts
to provide specialized handlers and functionality. In addition to providing access tostandard Cocoa classes and methods through the use of AppleScript/Objective-C,
AppleScript Libraries can publish their own scripting terminology, making it easier for
scripters to remember and incorporate custom commands in their scripts. AppleScript
Libraries have been made universally available through placement in new Script
Libraries directories created in the standard OS Library domains, enabling AppleScript
Libraries to be easily distributed between multiple computers running OS X Mavericks.

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The “use” clause
A new AppleScript construct called the “use” clause imports the terminology andfunctionality of AppleScript Libraries and scriptable applications through a simple
single-line declaration placed at the top of a script, such as “use application Finder,”or “use My AppleScript Text Library.” The handlers, scriptable objects, properties, andterminology of AppleScript Libraries and scriptable applications imported via a use
clause are automatically available globally throughout the hosting script—no longer
requiring that numerous “tell statements” or “tell blocks” be compiled and executed.
Scripts taking advantage of the use clause are more streamlined and clearer thansimilar scripts not implementing this new construct.
Notification support
AppleScript and Automator now allow system notifications to be created and displayed.
Users can incorporate notification banners and alerts into scripts and workflows with
the new default AppleScript Display Notification command or the new Automator
Display Notifications action. Automation processes requiring extended time to executeno longer need to display notification dialogs to communicate their progress or completion. Custom notifications—containing relevant information about the automation
processing—can be placed at the start, end, or throughout an automation workflow,
providing current feedback and status to the user.
Speakable-Workflows
If the Speakable Items feature is activated in the Accessibility System Preferences pane,
Automator will now present a new option in the Automator Save dialog: to save appletsas Speakable Items, automatically added to the Speakable Items Speech Recognitionarchitecture, and available for execution by simply speaking the names of the saved
applets. Speakable-Workflows extend the scope of the built-in Accessibility Speech
Recognition commands with the expansive automation architecture of OS X.

WebKitWebKit is an open source web browser engine developed by Apple. WebKit’s HTMLand JavaScript code began as a branch of the KHTML and KJS libraries from KDE.
WebKit is also the name of the OS X system framework version of the engine that’sused by Safari, Dashboard, Mail, and many other OS X applications.
Key features include:• Lightweight footprint• Great mobile support• Rich HTML5 functionality• Easy to embed in Cocoa and Cocoa Touch applications• Available as open source at webkit.org

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For More Information• Extensible Firmware Interface (EFI): See www.uefi.org• I/O Kit: See Kernel Programming Guide: I/O Kit Overview• Partition Schemes: See Technical Note TN2166: Secrets of the GPT• Recovery Partitions: See OS X: About OS X Recovery• Full-Disk Encryption: See OS X: About FileVault 2• Backup: See Mac Basics: Time Machine• File System Events: See Spotlight Overview• Launchd: See Daemons and Services Programming Guide• Grand Central Dispatch (GCD): See Concurrency Programming Guide• Sandboxes: See Code Signing Guide• Gatekeeper: See Distributing Outside the Mac App Store• Bonjour: See Bonjour Overview• XPC: See Daemons and Services Programming Guide: Creating XPC Services• iCloud: See iCloud Design Guide• LLVM: See LLVM Compiler Infrastructure Project• Xcode: See Xcode User Guide• Instruments: See Instruments User Guide• Automation: See AppleScript Overview• WebKit: See WebKit Objective-C Programming Guide

For More Information
For more information about OS X Mavericks,
visit www.apple.com/osx.

© 2013 Apple Inc. All rights reserved. Apple, the Apple logo, AirDrop, AirPlay, AirPort, AirPort Extreme, AppleScript, Apple TV, Aqua,
Back to My Mac, Bonjour, Cocoa, Cocoa Touch, Finder, iChat, iPad, iPhone, iWork, Keynote, MacBook, MacBook Air, Mac Pro, Numbers,
OpenCL, OS X, Pages, Safari, Spotlight, Time Capsule, Time Machine, and Xcode are trademarks of Apple Inc., registered in the U.S.
and other countries. iCloud is a service mark of Apple Inc., registered in the U.S. and other countries. App Store is a service mark ofApple Inc. Intel is a trademark of Intel Corp. in the U.S. and other countries. Java is a registered trademark of Oracle and/or its affiliates.
UNIX® is a registered trademark of The Open Group. Other product and company names mentioned herein may be trademarks of
their respective companies. October 2013 L524798A