YAML

YAMLBackground and Purpose

What is YAML?• Human friendly, cross language, Unicode based data

serialization language.• Pronounced in such a way as to rhyme with “camel”• Acronym for

YAML

Ain’t

Markup

Language

What is a data serialization language?

• A language used to convert or represent structured data or objects as a series of characters that can be stored on a disk.

• Examples:• CSV – Comma separated values• XML – Extensible markup language• JSON – JavaScript object notation• YAML – YAML ain’t markup language

Why YAML if XML?• Unlike XML which is not easily readable by humans,

YAML was created to be human-friendly and integrate easily with modern programming languages.

• Unlike with XML, YAML was intended to simplify the viewing and understanding of config files, log files, object persistence, and messaging, to allow the programmer to spend more time programming and less time formatting data.

YAML Design Goals• As stated in the YAML official specification, the design

goals for YAML in decreasing priority are:1. YAML is easily readable by humans

2. YAML data is portable between programming languages

3. YAML matches the native data structures of agile languages.

4. YAML has a consistent model to support generic tools.

5. YAML supports one-pass processing.

6. YAML is expressive and extensible.

7. YAML is easy to implement and use.

YAMLSyntax and Language Elements

Basic YAML Syntax Rules• Documents begin with --- and end with …• Indentation of lines denotes the structure within the

document.• Comments begin with #• Members of lists begin with –• Key value pairs use the following syntax

• <key>: <value>

Basic YAML Syntax Rules• Example:

---Student-Id: 11223344First-Name: JohnLast-Name: Smith

Phone-numbers: - 281.555.7689 - 713.555.8967 - 832.555.9980

Addresses: - street: 123 Main St. city: Houston state: TX...

Advanced YAML Syntax• There is more advanced syntaxes that exist that allow

YAML to represent• Relational trees

• *, <<, and & are used for node reference, array merges, and anchoring respectively

• User defined data types

• These are beyond the scope of this introductory tutorial.