OS X Mavericks

Core Technologies Overview

October 2013

Core Technologies Overview

OS X Mavericks

Contents

Page 4 Introduction

Page 5 System Startup

BootROM

EFI

Kernel

Drivers

Initialization

Address Space Layout Randomization (ASLR)

Compressed Memory

Power Eciency

App Nap

Timer Coalescing

Page 10 Disk Layout

Partition Scheme

Core 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

Bonjour

Page 25 Document Lifecycle

Auto Save

Automatic Versions

Document Management

Version Management

iCloud Storage

Core Technologies Overview

OS X Mavericks

Page 28 Data Management

Spotlight

Time Machine

Page 30 Developer Tools

Xcode

LLVM

Instruments

Accelerate

Automation

WebKit

Page 36 For More Information

Core Technologies Overview

OS X Mavericks

With more than 72 million users—consumers, scientists, animators, developers, and

system 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 Oce,

Adobe Photoshop, and thousands of other consumer applications—all side by side

with 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 innovations

in the core technologies that power Apple’s industry-leading user experiences. We walk

you through the entire software stack, from rmware and kernel to iCloud and devel-

oper tools, to help you understand the many things OS X does for you every time you

use your Mac.

Introduction

Core Technologies Overview

OS X Mavericks

BootROM

When you turn on the power to a Mac, it activates the BootROM rmware. 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 veries that

sucient 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 selected

by 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—denes the interface between an operating system

and platform rmware. It supersedes the legacy Basic Input Output System (BIOS) and

OpenFirmware architectures.

Once BootROM is nished and an OS X partition has been selected, control passes to

the boot.e boot loader, which runs inside EFI. The principal job of this boot loader is to

load 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 for

the user’s password, which the system needs so it can access the encrypted disk and

boot from it. Otherwise, loginwindow draws the login UI.

System Startup

Core Technologies Overview

OS X Mavericks

Kernel

The OS X kernel is based on FreeBSD and Mach 3.0 and features an extensible architec-

ture based on well-dened kernel programming interfaces (KPIs).

OS X was the rst operating system to ship as a single install that could boot into

either 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 qualied 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 object-

oriented 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 of

device-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, ecient 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 other

software 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, le 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 for

the kernel to nd the root device—the disk or network service where the rest of the

operating system resides.

Core Technologies Overview

OS X Mavericks

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 nds the root device, it roots BSD o of it.

Address Space Layout Randomization (ASLR)

Many malware exploits rely on xed 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 ll up, Compressed Memory

automatically compresses the least recently used items in memory, compacting them to

about 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 eciently. Through use of the dictionary-

based WKdm algorithm, compression and decompression are faster than reading and

writing to disk. If your Mac needs to swap les on disk, compressed objects are stored

in full-size segments, which improves read/write eciency and reduces wear and tear

on SSD and ash drives. The advantages of Compressed Memory include the following:

• Shrinks memory usage. Compressed Memory reduces the size of items in memory

that haven’t been used recently by more than 50 percent, freeing memory for the

applications you are currently using.

• Improves power eciency. Compressed Memory reduces the need to read and write

virtual memory swap les on disk, improving the power eciency of your Mac.

• Minimizes CPU usage. Compressed Memory is incredibly fast, compressing or decom-

pressing 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 both

reclaiming unused memory and accessing seldom-used objects in memory.

Power Eciency

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 some

cases 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, though

small 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.

Core Technologies Overview

OS X Mavericks

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 automati-

cally 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 the

existing IOKit IOPMAssertion API (used today in OS X to prevent the system from

sleeping 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 red. This

can mean signicant improvements in CPU idle time when running applications that

frequently check for data.

• I/O throttling—Assigns the lowest priority to disk or network activity associated with

a napping app. The rate at which an application can read or write data from a device

is signicantly reduced. In addition, I/O throttling reduces the chances that a back-

ground 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 a

smaller share of available processor time.

Timer Coalescing

Timer Coalescing minimizes the amount of system maintenance and background work

that is performed while your Mac is running on battery power. Some tasks are set to

run on battery power only after a specied 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 congured to never run on

battery 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 dier-

ent intervals to schedule routine work.

OS X Mountain Lion timers

125 milliseconds

Typical timer execution sample showing 125 milliseconds on an OS X Mountain Lion system

with no user interaction. Frequent execution of timers from various processes can prevent the

processor from idling.

Core Technologies Overview

OS X Mavericks

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 the

amount of time that the processor spends idling.

OS X Mavericks timers

125 milliseconds

A sample of the same scenario on OS X Mavericks: 125 milliseconds of timer execution with no

user activity. Executing timers at the same time reduces power use by maximizing processor

idle time.

Core Technologies Overview

OS X Mavericks

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 intro-

duced by Intel as part of EFI. The partitioning scheme is formally dened by:

• Section 11.2.2 of “Extensible Firmware Interface Specication,” version 1.1, available

from Intel

• Chapter 5, “GUID Partition Table (GPT) Format,” of the “Unied Extensible Firmware

Interface Specication,” version 2.0, available from the Unied EFI Forum

By 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 bless

command-line tool, though you can also bless specic folders or les. This partition is

usually also the root volume.

However, sometimes the boot partition is not the root, such as when the root partition

is 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 les

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 the

Command 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 nishes starting

up, 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 directly

from Apple’s servers, using a pristine Recovery HD image that provides all the same

functionality.

Disk Layout

Core Technologies Overview

OS X Mavericks

Core Storage

Layered between the whole-disk partition scheme and the le system used for a

specic partition is a new logical volume format known as Core Storage. Core Storage

makes it easy to dynamically allocate partitions while providing full compatibility with

existing lesystems. 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 le system layer allows OS X to dynamically mount, read, and write

to numerous local le 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+ le system. HFS+

supports 64-bit disk space addressing, 32-bit le allocation blocks, journaling, automatic

compression of les, fast B-tree lookups, robust alias support, and rich metadata—

including ne-grained access controls and extended attributes.

The Mac OS Extended le system functionality includes:

• Long lenames and international support. HFS+ allows more descriptive lenames,

with support for up to 255 characters and Unicode text encoding for international

and mixed-script lenames.

• Case sensitivity. OS X oers an optional case-sensitive le system format for HFS+,

allowing you to host les for use by UNIX applications that require case sensitivity.

• Large volume support. To accommodate massive databases, image archives, and

video volumes larger than 16TB, OS X can congure HFS+ volumes to use block sizes

larger than 4K.

• File system journaling. A robust journaling feature protects the integrity of the le

system in the event of an unplanned shutdown or power failure. With journaling,

the operating system automatically tracks le system operations and maintains a

continuous record of these transactions in a separate le, called a journal. After an

unexpected shutdown, the operating system can use the journal to return the le

system to a known state—eliminating the need to perform a consistency check on

the entire le system during startup. With a journaled le system, bringing a volume

back online takes just seconds, regardless of the number of les or the size of the

volume.

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 performance

and 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 two

volumes, or rebuild RAID volumes.

Core Technologies Overview

OS X Mavericks

Launchd

The kernel invokes launchd as the rst 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 as

open source under the Apache license.

File-based conguration

Each job managed by launchd has its own conguration le in a standard

launchd.plist(5) le format, which species 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 conguration scripts. Jobs

and plists can also be manually managed by the launchctl(1) command-line tool.

Launch on demand

launchd prefers for processes to run only when needed instead of blocking or poll-

ing 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 le path exists (for example, for a printer queue)

• When a device or le system is mounted

Smart scheduling

Like traditional UNIX cron jobs, launchd jobs can be scheduled for specic calendar

dates with the StartCalendarInterval key, as well as at generic intervals via

the StartInterval key. Unlike cron—which skips job invocations when the

computer 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 into

a single trigger.

User agents

launchd denes 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 work

that 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 Notes

GUI Aqua Has access to all GUI services; much like a login item

Non-GUI StandardIO Runs only in non-GUI login sessions

(for example, SSH login sessions)

Per-user Background Runs in a context that’s the parent of all contexts for

a given user

Pre-login Loginwindow Runs in the loginwindow context

Process Control

Core Technologies Overview

OS X Mavericks

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 access

for 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 the

latest 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 nal part of system initialization, launchd launches loginwindow. The

loginwindow program controls several aspects of user sessions and coordinates the

display of the login window and the authentication of users.

If a password is set, OS X requires users to authenticate before they can access the

system. 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

• Congures 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 le permissions, keychain access, and so on)

• Launches the Dock, Finder, and SystemUIServer

• Launches the login items for the user

Core Technologies Overview

OS X Mavericks

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 this

window 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 ecient system services. This radically simplies

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 ecient 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 can

perform more eciently on both single-processor and multiprocessor machines. Without

a pervasive approach such as GCD, even the best-written application cannot deliver

optimal performance across diverse environments because it lacks insight into every-

thing else happening on the system.

Blocks

Block 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”—eectively 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

Specication and its implementation as open source under the MIT license and added

blocks support to both GCC and Clang/LLVM.

Core Technologies Overview

OS X Mavericks

Queues

GCD dispatch queues are a powerful tool for performing tasks safely and eciently on

multiple CPUs. Dispatch queues atomically add blocks of code that can execute either

asynchronously or synchronously. Serial queues enable mutually exclusive access to

shared data or other resources without the overhead or fragility of locks. Concurrent

queues can execute tasks across multiple distinct threads, based on the number of

currently 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 rst-in/rst-out (FIFO) basis as long as there are

available 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 eect 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. When

the source res, GCD will schedule the handler block on the specic 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 bind-

ing a thread to the event source. Plus, since the handler is never run more than once

at a time, the block doesn’t even need to be reentrant; only one thread will attempt to

read or write any local variables.

OpenCL integration

Deeply integrated into OS X, OpenCL accelerates applications by tapping into the

parallel computing power of modern GPUs and multicore CPUs. Using a C99-based

language coupled with a exible API for managing data-parallel workloads, OpenCL

opens up a new range of computationally intensive algorithms for use in your

application.

You use OpenCL to transform your apps’ most performance-intensive routines into

computational “kernels.” Each kernel is runtime compiled by OpenCL and eciently

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 specic set of expected

operations. For example, a web browser regularly needs to read from the network, but

shouldn’t write to the user’s home folder without explicit permission. Conversely, a disk

usage monitor may be allowed to read directories and delete les, 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 be

used with all applications, and we require their use for apps distributed via the Mac

App Store.

Core Technologies Overview

OS X Mavericks

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 in

TrustedBSD. kauth identies 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 specied 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 specic entitlements that an application

must explicitly request by adding the appropriate key to a property list le in its appli-

cation bundle. Entitlements can control access to:

• The entire le system

• Specic 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 and

writing les.

User intent

While it may seem that virtually all applications would need to request broad entitle-

ments to read and write les, that isn’t the case. OS X tracks user-initiated actions,

such as dragging a le onto an application icon, and automatically opens a temporary

hole in the sandbox, allowing the application to read just that one le. In particular,

open and save panels run in a special-purpose PowerBox process that handles all user

interaction. This allows applications to only request entitlements for actions they need

to perform autonomously.

Code signing

Entitlements use code signing to ensure the privileges they specify only cover the

code originally intended. Code signing uses public key cryptography to verify that the

entity that created the entitlements (that is, the developer) is the same as the author

of the executable in question, and that neither has been modied.

Gatekeeper

Gatekeeper is a feature in OS X that helps protect you from downloading and install-

ing malicious software. Developers can sign their applications, plug-ins, and installer

packages with a Developer ID certicate to let Gatekeeper verify that they come from

identied developers.

Developer ID certicates

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.

Core Technologies Overview

OS X Mavericks

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 to

focus on one specic task.

No conguration needed

XPC executables and xpcservice.plist(5) conguration les are all part of a

single 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.

Core Technologies Overview

OS X Mavericks

Privilege separation

XPC processes each have their own sandbox, allowing clean separation of responsibili-

ties. For example, an application that organizes and edits photographs does not usually

need network access. However, it can create an XPC helper with dierent 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 le descriptors and

IOSurface media objects.

Core Technologies Overview

OS X Mavericks

Ethernet

Mac systems were the rst mass-market computers to ship with built-in Ethernet. OS X

today supports everything from 10BASE-T to 10 Gigabit Ethernet. The Ethernet capabili-

ties 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 recongures the connection depending on whether you are connecting to

a router or another computer, so you no longer need special crossover cables.

Autonegotiation

Autonegotiaton discovers and uses the appropriate transmission parameters for a

given 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 frames

This capability uses Ethernet frames of up to 9000 bytes with Gigabit Ethernet switches

that allow them.

TCP segmentation ooad

To reduce the work required of the CPU, TCP segmentation ooad lets the Network

Interface Card (NIC) handle splitting a large outgoing buer 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 les wirelessly with nearby users, even if you

aren’t on the same network. AirDrop leverages the wireless hardware on newer Mac

systems to nd and connect to other computers on an ad hoc basis, even if they are

already associated with dierent Wi-Fi networks.

Network Access

Core Technologies Overview

OS X Mavericks

Share les wirelessly with anyone around you using AirDrop.

AirPlay

AirPlay lets you stream music throughout your entire house—wirelessly. You can

share audio or mirror your screen from your Mac to an Apple TV or any other AirPlay-

enabled 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 dynamically

determines the optimal one to use for a given connection. Here are some examples of

where 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.

Core Technologies Overview

OS X Mavericks

• Routing all corporate trac 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 other

devices.

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 know

whether 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 to

ensure IPv6 interoperability between computers, mobile devices, and network equip-

ment used within the U.S. Government. USGv6 conformance tests were conducted and

validated by the ISO/IEC 17025 accredited InterOperability Laboratory at the University

of New Hampshire.

In addition, Apple has completed a USGv6 SDOC (Supplier’s Declaration of Conformity),

which will be on le 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 le services—SMB, AFP, and NFS—for sharing

les between Mac and PC.

SMB2

SMB2 is the new default protocol for sharing les in OS X Mavericks. SMB2 is superfast,

increases security, and improves Windows compatibility.

• Ecient. SMB2 features Resource Compounding, allowing multiple requests to be

sent in a single request. In addition, SMB2 can use large reads and writes to make

better use of faster networks as well as large MTU support for blazing speeds on

10 Gigabit Ethernet. It aggressively caches le and folder properties and uses oppor-

tunistic locking to enable better caching of data. It’s even more reliable, thanks to the

ability to transparently reconnect to servers in the event of a temporary disconnect.

• Secure. SMB2 supports Extended Authentication Security using Kerberos and

NTLMv2.

Core Technologies Overview

OS X Mavericks

• Compatible. SMB2 is automatically used to share les between two Mac computers

running OS X Mavericks, or when a Windows client running Vista, Windows 7, or

Windows 8 connects to your Mac. OS X Mavericks maintains support for AFP and

SMB network le-sharing protocols, automatically selecting the appropriate protocol

as needed.

AFP

The Apple Filing Protocol (AFP) is the traditional network le service used on the

Mac. 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 organiza-

tion using the same standard automounter maps supported by Linux and Solaris. For

enhanced security, NFS can use Kerberos authentication as an alternative to UNIX

UID-based authentication.

Access Control Lists

OS X supports both traditional UNIX le permissions and access control lists (ACLs),

oering administrators an unprecedented level of control over le and folder

permissions.

POSIX permissions

Standard UNIX le permissions, also known as Standard Portable Operating System

Interface (POSIX) permissions, allow you to assign one access privilege to the le’s

owner, one to a group, and one to everyone on the network. Multiple users and

multiple groups are not allowed, nor is ownership by a group. The traditional UNIX

model supports three permissions—read, write, and execute.

Access control lists

For exibility in complex computing environments, OS X includes le system access

control lists. With le system ACLs, any le object can be assigned multiple users and

groups, including groups within groups. Each le object can also be assigned both

allow and deny permissions, as well as a granular set of permissions for administrative

control, read, write, and delete operations. OS X supports a le permission inheritance

model, ensuring that user permissions are inherited when les are moved, rewritten,

or copied. ACLs may be set to allow a user to modify a le, but not to delete or even

rename 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, Open

Directory, 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 access

their 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.

Core Technologies Overview

OS X Mavericks

LDAPv3 support

To simplify integration into existing directory services, OS X supports the LDAP RFC

2307 standard. For greater exibility, 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 the

older Point-to-Point Tunneling Protocol (PPTP). OS X also includes a VPN framework

that developers can use to build additional VPN clients.

Firewalls

In addition to the ipfw2-based system-wide rewall, OS X includes an application

rewall that can be congured 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 and

connection type, enabling TCP to optimize performance when connecting to high-

bandwidth/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 Conguration 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 requiring

well-known port numbers. The ability of Bonjour to painlessly nd other computers

over 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 benets from this feature

automatically. When your host computer encounters a local network that lacks DHCP

address management, it nds an unused local address and adopts it without you

having to take any action.

Core Technologies Overview

OS X Mavericks

Multicast DNS

Multicast 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 your

name to your network address.

Service discovery

Service discovery allows applications to nd all available instances of a particular

type of service and to maintain a list of named services. The application can then

dynamically 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 enable

discovery 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 by

companies to publicize their intranet or by retailers to advertise promotional websites.

High-level APIs

OS X provides multiple APIs for publication, discovery, and resolution of network

services, as follows:

• NSNetService and NSNetServiceBrowser classes, part of the Cocoa Foundation frame-

work, 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 and

other 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 can

easily 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.

Core Technologies Overview

OS X Mavericks

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 ve minutes, whichever comes rst. If the

current 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 make

changes 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 snap-

shots of a document whenever you like.

OS X uses a sophisticated chunking algorithm to save only the information that has

changed, making ecient use of space on your hard drive (or iCloud). Versions under-

stands many common document formats, so it can chunk documents between logical

sections, not just at a xed 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 that

were 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 the

interval you want from the Lock documents pop-up menu.

When you share a document—for example through email, iChat, or AirDrop—only the

latest, nal 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.

Document Lifecycle

Core Technologies Overview

OS X Mavericks

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 of

previous 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 your

working 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 whenever

they 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 from

any device without having to sync or transfer les explicitly. Storing documents in your

iCloud 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 le system is shared by all running processes, conicts can occur when

two processes (or two threads in the same process) try to change the same le at the

same time. To avoid this type of contention, OS X includes support for le coordinators,

which enable developers to safely coordinate le access between dierent processes

or dierent threads.

File coordinators mediate changes between applications and the daemon that facili-

tates the transfer of the document to and from iCloud. In this way, the le coordinator

acts as a locking mechanism for the document, preventing applications and the daemon

from modifying the document simultaneously.

Core Technologies Overview

OS X Mavericks

Safe versions

Versions automatically stores iCloud documents. This means iCloud never asks you to

resolve conicts or decide which version to keep. It automatically chooses the most

recent version. You can always use the Browse Saved Versions option if you want to

revert to a dierent one. Versions’ chunking mechanism also minimizes the information

that needs to be sent across the network.

Ubiquitous metadata, lazy content

iCloud immediately updates the metadata (that is, the le name and other attributes)

for every document stored or modied 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 storage

and network bandwidth.

Web access

iCloud provides a range of powerful web applications to let you work directly with

your 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).

Core Technologies Overview

OS X Mavericks

Spotlight

Spotlight is a fast desktop search technology that helps you organize and search for

les based on either contents or metadata. It’s available to users via the Spotlight

window in the upper-right of the screen. Developers can embed Spotlight in their

own applications using an API available from Apple.

Standard metadata

Spotlight denes standard metadata attributes that provide a wide range of options for

consistently storing document metadata, making it easier to form consistent queries.

These include POSIX-style le attributes, authoring information, and specialized meta-

data for audio, video, and image le formats.

Extensible importers

Using OS X Launch Services, Spotlight determines the uniform type identier of a new

or modied le and attempts to nd an appropriate importer plug-in. If an importer

exists and is authorized, OS X loads it and passes it the path to the le.

Third parties can create custom importers that extract both standard and custom

metadata for a given le type and return a dictionary that is used to update the

Spotlight datastore.

Dynamic datastore

Every time you create, modify, or delete a le, the kernel noties the Spotlight engine

that it needs to update the system store. OS X accomplishes this with the high-

performance fsevents API.

Live update

Whenever OS X updates the datastore, it also noties the system results window

and any third-party client applications if the update causes dierent les to match or

not match the query. This ensures that the Mac always presents the latest real-time

information to the user.

Time Machine

Time Machine makes it easy to back up and restore either your entire system or

individual les.

Easy setup

To set up Time Machine, all you need to do is select a local disk or Time Capsule to

store the backups. With OS X, you can select multiple backup destinations for Time

Machine. OS X immediately starts backing up all your les in the background. After

the initial backup, it automatically creates new incremental backups every hour.

Data Management

Core Technologies Overview

OS X Mavericks

Coalescing changes

Time Machine leverages the fsevents technology developed for Spotlight to

continuously identify and track any folders (what UNIX calls directories) that contain

modied les. During the hourly backup, it creates a new folder that appears to repre-

sent the entire contents of your hard drive. In reality, it uses a variant of UNIX hard links

that mostly point to trees of unmodied folders already on the disk. Those trees are

eectively copy-on-write, so that future changes never aect the backup version.

Time Machine creates new trees inside a backup for any path that contains modied

folders. Time Machine creates new versions of those folders that contain links to the

current les, thus automatically capturing any changes that occurred in the past hour.

This avoids the overhead of either scanning every le on disk or capturing each and

every change to a le.

This technique allows each backup to provide the appearance and functionality of a

full backup while only taking up the space of an incremental backup (plus some slight

overhead for the metadata of modied 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 modied les even while you are disconnected

from 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 past

month, 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 notied whenever OS X deletes an

older backup, open Time Machine preferences, click the Options button, and select the

checkbox next to “Notify after old backups are deleted.”

Core Technologies Overview

OS X Mavericks

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 xes.

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 at

a 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 congure 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 dened interval.

Developer Tools

Core Technologies Overview

OS X Mavericks

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 down

each possible code path, identifying logical errors such as unreleased memory—well

beyond the simple syntax errors normally found at compile time.

Fix-it

Fix-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 xes 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,

oers 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 your

project is under source control, Xcode provides a special editor, called the version

editor, that compares dierent versions of les 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 set

of 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 and

more secure.

Core Technologies Overview

OS X Mavericks

Clang front-end

Clang is a high-performance front-end for parsing C, Objective-C, and C++ code as

part 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 technol-

ogy to be embedded within the Xcode IDE to enable static code analysis and Fix-it.

Comprehensive optimization

LLVM’s exible 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 of

memory management. By enabling ARC with the new Apple LLVM compiler, you never

need to manually track object lifecycles using retain and release, dramatically

simplifying 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 proling OS X and iOS code.

It is a exible 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 the

current instruments. Each instrument has its own track, which provides a chart of the

data collected by that instrument. You use this pane to select specic data points you

want to examine more closely.

Core Technologies Overview

OS X Mavericks

Multiple traces

Each time you click the Record button in a trace document, Instruments starts gather-

ing 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 to

compare behavior between dierent congurations.

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.

DTrace

DTrace 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 a

function entry point) to which DTrace can bind. When the function executes or the

event is generated, the associated probe res and DTrace runs whatever actions are

associated 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 an

action. Scripts let you use the features of DTrace to ne-tune the data you gather. That

data is then available as an Instruments track to compare with data from other instru-

ments 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 eciency 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.

Core Technologies Overview

OS X Mavericks

Automation

AppleScript

AppleScript is Apple’s native language for application automation, as used by the

AppleScript Editor. Its English-like syntax generates Apple events, which use a script-

ing dictionary (provided by most Mac applications) to programmatically create, edit, or

transform 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 workows, 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 applica-

tion’s dictionary, even generating appropriate header les 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, and

Automator workow les 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 of

allowing only applications downloaded from the Mac App Store and identied devel-

opers 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 and

abilities of AppleScript. AppleScript Libraries are user-created script les 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 to

standard 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.

Core Technologies Overview

OS X Mavericks

The “use” clause

A new AppleScript construct called the “use” clause imports the terminology and

functionality 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, and

terminology 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 than

similar scripts not implementing this new construct.

Notication support

AppleScript and Automator now allow system notications to be created and displayed.

Users can incorporate notication banners and alerts into scripts and workows with

the new default AppleScript Display Notication command or the new Automator

Display Notications action. Automation processes requiring extended time to execute

no longer need to display notication dialogs to communicate their progress or com-

pletion. Custom notications—containing relevant information about the automation

processing—can be placed at the start, end, or throughout an automation workow,

providing current feedback and status to the user.

Speakable-Workows

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 applets

as Speakable Items, automatically added to the Speakable Items Speech Recognition

architecture, and available for execution by simply speaking the names of the saved

applets. Speakable-Workows extend the scope of the built-in Accessibility Speech

Recognition commands with the expansive automation architecture of OS X.

WebKit

WebKit is an open source web browser engine developed by Apple. WebKit’s HTML

and 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’s

used 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

Core Technologies Overview

OS X Mavericks

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 of

Apple 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 aliates.

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

For More Information

For more information about OS X Mavericks,

visit www.apple.com/osx.

• Extensible Firmware Interface (EFI): See www.ue.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