Navigating the Programmable Web

Don Box and Steve MaineURI JockeysMicrosoft Corporation

About This Talk…Goals and Bits

GoalsHow do my programs use the web?How do my programs become part of the web?How do I do this efficiently and pragmatically?

BitsStuff that's already shipped (lots)Stuff that will ship in Orcas (lots more)Stuff that will ship in TBD (a couple of things)

About The Web…Stating the Obvious

GET is More Important Than

You Think

It’s the URI, Stupid

Formats Matter

It's The URI, StupidQuery, S-Expression, or Opaque Identifier

The web pivots on URIsEasy to write down, share, and compareHierarchy matches many information modelsCan be treated as opaque identifier (a la a GUID)Can be treated as a structured expression (a la S-Expr)

URI-space for a given service often infiniteMay also be state/data dependentCommonplace to use template syntax to specify "holes" in URI space (a la A9 and Joe Gregorio)

It's The URI, Stupid,UriTemplates: Embrace Infinity

System.UriTemplate ("Orcas") provides runtime support for URI template syntaxUriTemplate.Bind fills in template holes with actual valuesUriTemplate.Match extracts actuals from concrete URIUriTemplateTable provides matching over multiple candidate templates

Most specific match wins

It's The URI, Stupid,UriTemplates

Uri baseAddress = new Uri( “http://localhost:81” );string artist = "Led Zeppelin";string album = "Four"; UriTemplate template = new UriTemplate(“music/{artist}/{album}?format={format}" );

Uri boundUri = template.BindByPosition( baseAddress, artist, album, "rss" ); //boundUri:// http://localhost:81/music/Led%20Zeppelin/Four?format=rss

UriTemplateMatch match = template.Match( baseAddress, boundUri );

Debug.Assert( match.BoundVariables[“artist”] == artist );Debug.Assert( match.BoundVariables[“album”] == album );Debug.Assert( match.BoundVariables[“format”] == “rss” );

Using URIs and UriTemplates

demo

Watch Steve Code…

GET is More Important Than You ThinkView It vs. Do It

GET CHAOS

Bounded SemanticsMeans “retrieve”No “unsafe” side-effectsExpectation of idempotency

Unbounded SemanticsMeans “do something”

Side-effects allowedNo expectation of idempotency

Most of the world is GETThe rest is relative chaos

GET is More Important Than You ThinkView It vs. Do It

GET CHAOS

“Add”, “Create”, or “Invoke”?

POST PUT DELETE OTHER

“Replace” or “Partial

Update”?

“Delete” or “Rollback”?

What aboutSUBSCRIBE

NOTIFYUPSERT

ENQUEUEMKCOL

…

GET is More Important Than You ThinkView It vs. Do It

Turn off DELETE

Turn off PUT Turn off POST

Turn off GET

Degree of Resultant Apocalypse

Rectal Itching

The Simpsons Movie

Dogs/cats sleepingtogether; mass hysteria

The Oprah Channel

Lindsay Lohan

Smooth Jazz

GET is More Important Than You ThinkWebGet/WebInvoke

[WebGet] ("orcas") adds GET support to WCF service operations

Allows target URI space to be specified as URI templateTemplates parameters mapped to method parametersWebOperationContext provides easy access to web specifics (e.g., headers, status codes)

[WebInvoke] provides same for other HTTP methods

POST is default method

GET is More Important Than You ThinkWebHttpClient : The Opaque/Transparent Duality

[WebGet]/[WebInvoke] work great for "transparent" URI with well-understood structure

Ideal for server, OK (at best) for client

WebHttpClient ("experimental") is a more flexible client-side programming model

Supports both transparent and opaque URIEasier to use and more scalable than current WebClient API

Using WebGet and WebHttpClient

demo

Watch Steve Code…

Formats MatterSchemas, Schemas and more Schemas

Uniform operations are half the web "reach" propositionUniform formats for HTTP entity bodies are the other halfHTML was the ubiquitous format for projecting UXAlas, multiple format(s) for exchanging data

Original vision for "web data" based on plain old XML (POX)JSON offers simpler format/data modelRSS/ATOM constrain POX by adding list structureSOAP constraints POX by adding header processing model

Formats MatterWCF and Formats

WebGet/WebInvoke supports XML, JSON, or opaque binary formats for request/response data

SOAP and POX were in the box in V1

SyndicationFeed/SyndicationItem provide rich programming model for dealing with RSS/ATOM data

Usable standalone or as WCF message contentIntegrates with serialization stacks for feed/item extensibility

Fun with Formats

demo

Watch Steve Code…

Stuff We UsedThe Code/Time Continuum

Already Shipped

System.UriWebClient

WPFWCF

Ships in “Orcas”

UriTemplate[WebGet]

SyndicationFeedLINQ for XML

JSON Formatter

Speculative Bits

WebHttpClient

"Orcas" and the WebCode and Ideas

GET is More Important Than

You Think

It’s the URI, Stupid

Formats Matter

UriTemplate

[WebGet]

SyndicationFeed

LINQ for XML

JSON Formatter

Talk amongst ourselves

discussion

Please fill out your eval

evaluation

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