Data Decay and the Illusion of the PresentDan Lynn

@danklynn

Keeps all your contacts in one place and keeps them automatically up to date.

Based in Denver, Colorado

CTO & Co-Founderdan@fullcontact.com

@danklynn

Let’s talk about time.

The Past

http://wearcam.org/dundas-square/2004sep23/cement.jpg

The FutureThe Past

The Present

Unless you’re a yogi, you probably can’t even perceive the present.

http://applemagazine.com/wp-content/uploads/2012/12/exc.jpeg

- Washington Post (September 24, 2013)

“Traders may have gotten last week’s Fed news 7 milliseconds early“

It’s just a question of how old.Data is always old

How do APIs keep data fresh?

Polling

• Simple

• But can lead to complex scheduling

• Trades efficient use of resources for fresh data.

GET /notifications?since=1382630675166

- Zapier“98.5% of polls are wasted”

Ping/Pull• XML-RPC

• Facebook Realtime updates

• Avoids scheduled polling

• Consumer must host an endpoint

• Moderate latency (3 hops)

• Complex

Push• Github service hooks

• Content of change is pushed

• Payload can be diff or full resource

• Consumer must host an endpoint

• Lowest latency (1 hop)

We are moving towards a push-based

API ecosystem

“Security is abnormally slow.”Flight Delays

“Dan Lynn changed his phone number”Contact Information

Dynamic SubscriptionsPOST /contacts/123/subscriptions

{

"url" : "https://.../updates?contactId=123"

}

201 Created

{ "url" : "/contacts/123/subscriptions/a3b"}

Dynamic SubscriptionsDELETE /contacts/123/subscriptions/a3b

200 OK

So which model is right for your API?

What’s the cost of acting on wrong

data?

$100 per contact

Source: SiriusDecisions

If left untreated

Low time sensitivity?Polling is fine.

High time sensitivity?Go with push.

APIs are combating information asymmetry.

Thanks!@danklynn

See Also:http://xmpp.org/extensions/xep-0060.html

https://code.google.com/p/pubsubhubbub/http://www.resthooks.org/