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Medium 9780596518578

C. Capacity Tools

John Allspaw O'Reilly Media ePub

MEASUREMENT, MONITORING, AND MANAGEMENT TOOLS INFORM AND GUIDE YOUR CAPACITY PLAN. IN THIS appendix, I've compiled a list of some of the more popular tools and utilities for your reference. We use a good deal of these tools at Flickr, and some of them are simply open-source equivalents of software that have been written within Yahoo! to achieve the same goal.

As we discussed in Chapter3, there can be a lot of overlap in event notification software (tools that alert on resources based on thresholds) and metric collection and display tools. Some of the following tools have alerting abilities, some of them are more focused on graphing and collection, and some have both.

Born out of the HPC community, Ganglia has a very active community of users and developers. We use Ganglia extensively at Flickr, as do Wikipedia and other large-scale social networking sites.

We use a modified version of Nagios at Yahoo! to monitor services across thousands of machines.



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Medium 9781847772077

A Wedding Photograph

Rory Waterman Carcanet Press Ltd. PDF
Medium 9780596514471

Chapter 2: Writing Systems and Scripts

Ken Lunde O'Reilly Media PDF

Chapter 2

Writing Systems and Scripts

Reading the introductory chapter provided you with a taste of what you can expect to learn about CJKV information processing in this book. Let’s begin the journey with a thorough description of the various CJKV writing systems that serve as the basis for the characters set standards that will be covered in Chapter 3.

Mind you, we have already touched upon this subject, though briefly, in the introductory chapter, but there is a lot more to learn! After reading this chapter, you should have a firm grasp of the types of characters, or character classes, used to write CJKV text, specifically the following:

• Latin characters—including transliteration and romanization systems

• Zhuyin—also called bopomofo

• Kana—hiragana and katakana

• Hangul syllables—including jamo, the elements from which they’re made

• Ideographs—originating in China

• Non-Chinese ideographs—originating in Japan, Korea, and Vietnam

Knowing that each of these character classes exhibits its own special characteristics and often has locale-specific usages is important to grasp. This information is absolutely crucial for understanding discussions elsewhere in this book. After all, many of the problems and issues that caused you to buy this book are the result of the complexities of these writing systems. This is not a bad thing: the complexities and challenges that we face are what make our lives interesting, and to some extent, unique from one another.

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Medium 9781449314903

A First Patch

Peter Brinkmann O'Reilly Media ePub

Lets create our first Pd patch. Select File New. (For clarity, Ill spell out the menu items here, but nobody actually uses menus when patching. Using keyboard shortcuts for the most important operations quickly becomes second nature.) Youll see an empty canvas (Figure2-3).

Figure2-3.The beauty of a blank canvas

This looks quite different from other graphical user interfaces. It offers no guidance, no buttons to click, no features to discover. A usability expert would decry the tyranny of the blank canvas. Dont despair, though. Once you learn your way around Pd, youll appreciate the clarity that comes with the absence of visual clutter. Pd makes no assumptions as to what you want to do, or how you want to do it. A blank canvas may seem daunting, but it is the right foundation for creative work.

Select the menu item Put Object. Youll see a dashed box that will follow your mouse pointer. Move it to the center of your canvas and type osc~ 220 into the box. Now click outside the box and the box will become solid. You have just created a sinusoid with a frequency of 220Hz (Figure2-4).

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Medium 9780596000455

3. Cryptography Basics

Simson Garfinkel O'Reilly Media ePub

This chapter explains the basics of cryptography, on which many secure Internet protocols are based. Cryptography is a complex topic and in this chapter were obviously presenting only a summary. Chapter 4 describes how cryptography is used today on the Web. For more complete information on cryptography concepts and algorithms, see the references in Appendix E.

Cryptography is a collection of mathematical techniques for protecting information. Using cryptography, you can transform written words and other kinds of messages so that they are unintelligible to anyone who does not possess a specific mathematical key necessary to unlock the message. The process of using cryptography to scramble a message is called encryption . The process of unscrambling the message by use of the appropriate key is called decryption . Figure 3-1 illustrates how these two processes fit together.

Figure3-1.Encryption is a process that uses a key to transform a block of plaintext into an encrypted ciphertext. Decryption is the process that takes an encrypted ciphertext and a decryption key and produces the original plaintext.

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