Google Data Protocol Guy Mark Lifshitz

Motivation Google’s Mission: – Organize the world’s information – Make information universally accessible – Provide tools to access your information Avoid limitations on contexts: – Not limited to Google – Not limited to browsers

Foundation REST AtomPub JSON RSS

REST “Representational state transfer”

REST Simple Lightweight Scalable Maps well to representing and exposing data

REST 1. Client sends a request to server 2. Server process the request 3. Server returns a response

AtomPub “Atom Publishing Protocol” (RFC 5023)

AtomPub Originally created for blogs Feed based Feeds are found at a specific URI An Atom Reader looks for entries in a feed

AtomPub Create Retrieve Update Delete

AtomPub Create – PUT Retrieve – GET Update – GET, modify feed, PUT Delete – DELETE

Calendar Atom Feed Google Calendar T10:46:25.244Z Coach's's personal settings 1 Coach T10:46:25.245Z

Calendar Atom Feed Google Calendar T10:46:25.244Z Coach's's personal settings 1 Coach T10:46:25.245Z

Calendar Atom Feed Google Calendar T10:46:25.244Z Coach's's personal settings 1 Coach T10:46:25.245Z

Calendar Atom Feed Google Calendar T10:46:25.244Z Coach's's personal settings 1 Coach T10:46:25.245Z

Calendar Atom Feed Google Calendar T10:46:25.244Z Coach's's personal settings 1 Coach T10:46:25.245Z

Calendar Atom Feed Google Calendar T10:46:25.244Z Coach's's personal settings 1 Coach T10:46:25.245Z

Calendar Atom Feed Google Calendar T10:46:25.244Z Coach's's personal settings 1 Coach T10:46:25.245Z

JSON “ JavaScript Object notation”

JSON Properties – Lightweight data interchange format – Widespread use among web developers – Easy to read and write – Can parse JSON using any language – JSON structures map directly to data structures used in most programming languages Within the Google Data Protocol, JSON objects simply mirror the Atom representation.

JSON vs. XML "firstName": "John", "lastName": "Smith", "age": 25, "address": { "streetAddress": "21 2nd Street", "city": "New York", "state": "NY", "postalCode": "10021“ }, "phoneNumbers": [ { "type": "home“, "number": " "}, { "type": "fax", "number": " " } ], "newSubscription": false, "companyName": null

JSON vs. XML nd Street New York NY false

GData

Additional Features Authentication Queries Concurrency Common Elements Batch Processing

Authentication ClientLogin – Desktop applications – Uses text input in application "mypassword"); AuthSub – 3 rd party websites – Directs you to Google’s website.

Query Add query to the URL Basic: Events before February 11 th 2010, ordered by date ?start-max= &orderby=starttime

Query Use the API to build queries CalendarQuery myQuery = new CalendarQuery(feedUrl); myQuery.setMinimumStartTime(DateTime.parseDateTime(" T00:00:00")); myQuery.setMaximumStartTime(DateTime.parseDateTime(" T23:59:59"));... CalendarEventFeed resultFeed = myService.query(myQuery, Feed.class);

Additional Features Authentication Queries Concurrency Common Elements Batch Processing

Additional Features Authentication Queries Concurrency Common Elements – “Kines” Batch Processing

Additional Features Authentication Queries Concurrency Common Elements Batch Processing

APIs

Libraries Java.NET PHP Python JavaScript Obj-C

API Library

Links

Example public class CalendarTest { public static void main(String[] args) { CalendarService myService = new CalendarService("exampleCo-exampleApp-1.0"); "pa$$word"); URL feedUrl = new URL(" CalendarFeed resultFeed = myService.getFeed(feedUrl, CalendarFeed.class); System.out.println("Your calendars:"); System.out.println(); for (int i = 0; i < resultFeed.getEntries().size(); i++) { CalendarEntry entry = resultFeed.getEntries().get(i); System.out.println("\t" + entry.getTitle().getPlainText()); }

Request GET PUT DELETEE HEAD POST – All Methods – POST not safe or idempotent Intermediaries can be added in between – Proxies and Gateways – Can add performance

Protocol Client Server Stateless – Requests are independent (don’t know what other interactions are doing) Layered – HTTP intermdiaries can be added without changing behaviour Cacheable

REST Architectural Style Architecture of the web HTTP (protocol) Request Response. Client requests from server, and server responds.

Extends Atom 1.0 RSS 2.0 Atom Publishing Protocol (APP). Google Data protocol extends those standards in various ways, using the extension mechanisms built into the standards. Feeds conform to either the Atom or RSS syndication formats. The publishing model conforms to the Atom Publishing Protocol.

AtomPub “Atom Publishing Protocol” (RFC 5023) Web syndication is an effective and popular method for providing and aggregating content. It also lets you send data to Google and update data that Google maintains.

Benefits Efficiency – Caches Scalability – Large set of origin servers Performance to user – Partial rendering of html and such.

Calendar Feed <feed xmlns=" xmlns:openSearch=" xmlns:gCal=" xmlns:gd=" gd:etag="W/"Ck8FQ3Y4cCp7I2A9WxVVEkU.""> T10:46:25.244Z Coach's's personal settings Coach Google Calendar T10:46:25.245Z T10:46:25.245Z

Calendar Feed <feed xmlns=" xmlns:openSearch=" xmlns:gCal=" xmlns:gd=" gd:etag="W/"Ck8FQ3Y4cCp7I2A9WxVVEkU.""> T10:46:25.244Z Coach's's personal settings Coach Google Calendar T10:46:25.245Z T10:46:25.245Z

Calendar Feed <feed xmlns=" xmlns:openSearch=" xmlns:gCal=" xmlns:gd=" gd:etag="W/"Ck8FQ3Y4cCp7I2A9WxVVEkU.""> T10:46:25.244Z Coach's's personal settings Coach Google Calendar T10:46:25.245Z T10:46:25.245Z

Calendar Feed T10:46:25.245Z

Atom Feeds Example Feed A subtitle. urn:uuid:60a76c80-d399-11d9-b91C e0af T18:30:02Z John Doe Atom-Powered Robots Run Amok urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a T18:30:02Z Some text.

Atom Feeds Example Feed A subtitle. urn:uuid:60a76c80-d399-11d9-b91C e0af T18:30:02Z John Doe Atom-Powered Robots Run Amok urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a T18:30:02Z Some text.

Atom Feeds Example Feed A subtitle. urn:uuid:60a76c80-d399-11d9-b91C e0af T18:30:02Z John Doe Atom-Powered Robots Run Amok urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a T18:30:02Z Some text.

Atom Feeds Example Feed A subtitle. urn:uuid:60a76c80-d399-11d9-b91C e0af T18:30:02Z John Doe Atom-Powered Robots Run Amok urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a T18:30:02Z Some text.

Atom Feeds Example Feed A subtitle. urn:uuid:60a76c80-d399-11d9-b91C e0af T18:30:02Z John Doe Atom-Powered Robots Run Amok urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a T18:30:02Z Some text.

Atom Feeds Example Feed A subtitle. urn:uuid:60a76c80-d399-11d9-b91C e0af T18:30:02Z John Doe Atom-Powered Robots Run Amok urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a T18:30:02Z Some text.

Atom Feeds Example Feed A subtitle. urn:uuid:60a76c80-d399-11d9-b91C e0af T18:30:02Z John Doe Atom-Powered Robots Run Amok urn:uuid:1225c695-cfb8-4ebb-aaaa-80da344efa6a T18:30:02Z Some text.