XML Versus the New Kids on the Block (ZC10 2010-11-03)

XML VS. THE NEW KIDS ON THE BLOCK

David Zülke

David Zuelke

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@dzuelke

TODAY'S MENU • XML (and where it took a wrong turn) • HTML 5 (and why it makes me very, very angry) • JSON (and why it's not always as useful as you may think) • YAML (and why it makes my eyes bleed)

but ﬁrst

I'd like to hear from you, dear audience

what do you love, hate, adore or loathe with a passion?

XML eXtensible Markup Language

"extensible" mostly refers to the Namespaces concept

VALIDATION • XML Schema (validates the grammar of a document) • RELAX NG (like XML Schema, just full of win) • Except it's so awesome it sucks at reporting errors :( • Schematron (validates the semantics of a document) • DTD (RRRRRRRAAAAAAAAAAAAAAAAAGGGGEEEE)

OTHER GOODIES • XPath and XQuery for querying documents • XPath is an expression syntax, XQuery a full query language • XSLT to transform documents to XML, HTML, text, ... • Makes heavy use of XPath • XIncludes • Allow re-use of content within and across documents

READING AND WRITING • Push Parsing, uses events to notify app during parsing • Example: SAX • Pull Parsing, allows app to retrieve or skip elements • Example: PHP's ext/xmlreader • DOM, constructs an object representation of the tree • Example: DOM (duh)

but most importantly

Mixed Content!

<?xml version="1.0" encoding="utf-‐8"?> <products xmlns="http://acme.com/shop/products"> <product id="123"> <name>Bacon</name> <price>5.99</price> </product> </products>

<?xml version="1.0" encoding="utf-‐8"?> <products xmlns="http://acme.com/shop/products"> <product id="123"> <name>Bacon</name> <price>5.99</price> OMNOMNOM Bacon </product> </products>

and you can add elements without changing the structure

<?xml version="1.0" encoding="utf-‐8"?> <products xmlns="http://acme.com/shop/products"> <product id="123"> <name>Bacon</name> <price>5.99</price> </product> </products>

<?xml version="1.0" encoding="utf-‐8"?> <products xmlns="http://acme.com/shop/products"> <product id="123"> <name xml:lang="en">Bacon</name> <name xml:lang="de">Speck</name> <price>5.99</price> </product> </products>

<?xml version="1.0" encoding="utf-‐8"?> <products xmlns="http://acme.com/shop/products"> <product id="123"> <name xml:lang="en">Bacon</name> <name xml:lang="de">Speck</name> <price>5.99</price> <link rel="category" href="..." /> </product> </products>

XML: doing it right

<?xml version="1.0" encoding="utf-‐8" standalone="yes"?> <search> <total_results>6</total_results> <items_per_page>2</items_per_page> <start_index>1</start_index> <link href="http://openapi.lovefilm.com/catalog/games?start_index=1&items_per_page=2&term=old" rel="self" title="self"/> <link href="http://openapi.lovefilm.com/catalog/games?start_index=3&items_per_page=2&term=old" rel="next" title="next"/> <link href="http://openapi.lovefilm.com/catalog/games?start_index=5&items_per_page=2&term=old" rel="last" title="last"/> <catalog_title> <can_rent>true</can_rent> <release_date>2003-‐09-‐12</release_date> <title full="Star Wars: Knights of the Old Republic" clean="Star Wars: Knights of the Old Republic"/> <id>http://openapi.lovefilm.com/catalog/title/59643</id> <adult>false</adult> <number_of_ratings>574</number_of_ratings> <rating>4</rating> <category scheme="http://openapi.lovefilm.com/categories/catalog" term="games"/> <category scheme="http://openapi.lovefilm.com/categories/format" term="Xbox"/> <category scheme="http://openapi.lovefilm.com/categories/genres" term="Adventure"/> <category scheme="http://openapi.lovefilm.com/categories/genres" term="Role-‐playing"/> <category scheme="http://openapi.lovefilm.com/categories/certificates/bbfc" term="TBC"/> <link href="http://openapi.lovefilm.com/catalog/title/59643/synopsis" rel="http://schemas.lovefilm.com/synopsis" title="synopsis"/> <link href="http://openapi.lovefilm.com/catalog/title/59643/reviews" rel="http://schemas.lovefilm.com/reviews" title="reviews"/> <link href="http://www.lovefilm.com/product/59643-‐Star-‐Wars-‐Knights-‐of-‐the-‐Old-‐Republic.html?cid=LFAPI" rel="alternate" title="web page"/> </catalog_title> </search>

which brings me to...

HATEOAS AND HYPERMEDIA The Main Ingredient For Your REST API

XML: doing it wrong

<?xml version="1.0" encoding="UTF-‐8"?> <!DOCTYPE plist PUBLIC "-‐//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-‐1.0.dtd"> <plist version="1.0"> <dict> <key>DefaultProfileChoices</key> <dict> <key>AC Power</key> <integer>2</integer> <key>Battery Power</key> <integer>1</integer> <key>UPS Power</key> <integer>1</integer> </dict> <key>SystemProfileDefaults</key> <array> <!-‐-‐ Profile 0 -‐-‐> <dict> <!-‐-‐ AC Power -‐ unused -‐-‐> <key>AC Power</key> <dict> <!-‐-‐ ... -‐-‐> </dict> </dict> </array> </dict> </plist>

but please do not serialize objects to XML (I'm looking at you, SOAP)

HTML 5 Such a mess :(

HTML 5 • Neither SGML nor XML • so browser vendors need to write new (inefﬁcient) parsers • Does not have a DTD anymore • how could it, given how it's not SGML... • Completely idiotic stuff like data-* attributes • And they're even proud of it...

<li class="user" data-‐name="John Resig" data-‐city="Boston" data-‐lang="js" data-‐food="Bacon"> John says: Hello, how are you? </li>

but that's already possible in XML!

<li class="user" xmlns:myapp="http://myapp.com/v1" myapp:name="John Resig" myapp:city="Boston" myapp:lang="js" myapp:food="Bacon"> John says: Hello, how are you? </li>

JSON JavaScript Object Notation

JSON PROS AND CONS • Quite efﬁcient, simple, universally supported in many languages • Very good for serializing objects • Built-in types, do not need explicit declaration • No schemas • No mixed content

win: store arbitrary keys and values

{ "_id" : "bc2a41170621c326ec68382f846d5764", "_rev" : "2612672603", "item" : "orange", "prices" : { "Fresh Mart" : 1.99, "Price Max" : 3.19, "Citrus Circus" : 1.09 } }

fail: use it as query language for your pile of crap database

{ foo: "bar" } { x : 3, y : "foo" } { $or : [ { a : 1 } , { b : 2 } ] } { j : { $ne: 3 }, k : { $gt: 10 } } { x : 3 }, { z : 1 } { j : { $in : [2,4,6] } } { "author.name" : "joe" }

YAML Yet Another Markup Language

YAML Yet Another Markup Language YAML Ain't Markup Language

recursive acronyms are cool

YAML also was cool at some point

a simple markup language, perfect for conﬁguration ﬁles

autoload: # plugins plugins_lib: name: plugins lib path: %SF_PLUGINS_DIR%/*/lib recursive: true exclude: [] plugins_module_lib: name: plugins module lib path: %SF_PLUGINS_DIR%/*/modules/*/lib prefix: 2 recursive: true exclude: [] # project project: name: project path: %SF_LIB_DIR% recursive: true exclude: [model, symfony, deprecated]

but then...

foo: | -‐-‐-‐ foo: bar -‐-‐-‐ yo: baz bar: | fooness clipped: | This has one newline. same as "clipped" above: "This has one newline.n" stripped: |-‐ This has no newline. same as "stripped" above: "This has no newline." kept: |+ This has four newlines. same as "kept" above: "This has four newlines.nnnn" -‐ &showell Steve -‐ Clark -‐ Brian -‐ Oren -‐ *showell

YAML DRAWBACKS • Makes your eyes bleed • No schemas or other forms of validation • Forgeta newline somewhere and the parser might look at you, helpless, like a deer in headlights • No mixed content

CONCLUSION • XML for hypermedia, documents, your new REST API • JSON for serializing objects and storing them in e.g. CouchDB • YAML for your conﬁguration ﬁles

!e End

Questions?

THANK YOU! This was http://joind.in/2269 by @dzuelke

XML Versus the New Kids on the Block (ZC10 2010-11-03)

by David Zuelke on Nov 04, 2010

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XML Versus the New Kids on the Block (ZC10 2010-11-03) — Presentation Transcript

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