Dare Obasanjo aka Carnage4Life - Google OpenS...

来源:百度文库 编辑:16楼社区 时间:2021/06/14 22:20:49
 Saturday, November 03, 2007
Google OpenSocial: Technical Overview and Critique
Disclaimer: This post does not reflect the opinions, thoughts, strategies or future intentions of my employer. These are solely my personal opinions. If you are seeking official position statements from Microsoft, please gohere.
One of the Google folks working onOpenSocial sent me a message viaFacebook asking what I thought about the technical details of the recent announcements. Since my day job is working on social networking platforms for Web properties at Microsoft and I'm deeply interested in RESTful protocols, this is something I definitely have some thoughts about. Below is what started off as a private message but ended up being long enough to be it's own blog post.
First Impressions
In reading theOpenSocial API documentation it seems clear that is intended to be the functional equivalent of the Facebook platform. Instead of theFacebook users and friends APIs, we get theOpenSocial People and Friends Data API. Instead of theFacebook feed API, we get theOpenSocial Activities API. Instead of theFacebook Data Store API, we get theOpenSocial Persistence Data API. Instead ofFQL as a friendly alternative to the various REST APIs we geta JavaScript object model.
In general, I personally prefer the Facebook platform to OpenSocial. This is due to three reasons
There is no alternative to the deep integration into the Web site's user experience that is facilitated withFBML.   I prefer idiomatic XML to tunnelling data through Atom feeds in ways that [in my opinion] add unnecessary cruft. The Facebook APIs encourage developers to build social and item relationship graphs within their application while the OpenSocial seems only concerned with developers stuffing data in key/value pairs.
The Javascript API
At first I assumed theOpenSocial JavaScript API would provide similar functionality to FBML given the large number of sound bites quoting Google employees stating that instead of "proprietary markup" you could use "standard JavaScript" to buildOpenSocial applications. However it seems the JavaScript API is simply a wrapper on top of the various REST APIs. I'm sure there's some comment one could make questioning if REST APIs are so simple why do developers feel the need to hide them behind object models?
Given the varying features and user interface choices in social networking sites, it is unsurprising that there is no rich mechanism specified for adding entry points to the application into the container sites user interface. However it is surprising that no user interface hooks are specified at all. This is surprising given that there are some common metaphors in social networking sites (e.g. a profile page, a friends list, etc) which can be interacted with in a standard way.  It is also shocking that Google attacked Facebook's use of "proprietary markup" only to not even ship an equivalent feature.
The People and Friends Data API
ThePeople and Friends Data API is used to retrieve information about a user or the user's friends as an Atom feed. Each user is represented as an atom:entry which is aPersonKind (which should not be confused with anAtom person construct). It is expected that the URL structure for accessing people and friends feeds will be of the form  http:///feeds/people/ and http:///feeds/people//friends respectively.
Compare the following response to a request for a user's information using OpenSocial with the equivalent Facebook API call response.
GET http://orkut.com/feeds/people/14358878523263729569
Elizabeth Bennet

51.668674 -0.066235

Below is the what the above information would look like if returned by Facebook'susers.getInfo method


Palo Alto
United States


I've already mentioned that I prefer idiomatic XML to tunnelling data through Atom feeds. Comparing the readability of both examples should explain why.
The Activities Data API
A number of social networking sites now provide a feature which enables users to see the recent activities of members of their social network in an activity stream. TheFacebook news feed,Orkut's updates from your friends, and theWindows Live Spaces what's new page are all examples of this feature. TheOpenSocial Activities Data API provides a mechanism for OpenSocial applications to access and update this activity stream as an Atom feed. All of the users activities or all activities from a specific application can be accessed using URIs of the form  http:///activities/feeds/activities/user/ and http:///activities/feeds/activities/user//source/ respectively.
Currently there is no reference documentation on this API. My assumption is that since Orkut is the only OpenSocial site that supports this feature, it is difficult to produce a spec that will work for other services without it being a verbatim description of Orkut's implementation.
There are some notes on how Orkut attempts to prevents applications from spamming a user's activity stream. For one, applications are only allowed to update the activity stream for their source directly instead of the activity stream for the user. I assume that Google applies some filter to the union of all the source specific activity streams before generating the user's activity feed to eliminate spam. Secondly, applications are monitored to see if they post too many messages to the activity stream or if they post promotional messages instead of the user's activities to the stream. All of this makes it seem difficult to see how one could specify the behavior of this API and feature set reliably for a diverse set of social networking sites.
The Persistence Data API
TheOpenSocial Persistence API allows applications to store and retrieve key<->value pairs that are either user-specific or are global to the application. An example of the former is a listing of company name and stock ticker pairs while an example of the latter is a user's stock portfolio. The feed of global key<->value pairs for an application can be accessed at a URL of the form http:///feeds/apps//persistence/global for the entire feed and http:///feeds/apps//persistence/global/ if seeking a particular key<->value pair. User-specific key<->value pairs are available at the URL of the form http:///feeds/apps//persistence//instance/.
This is probably the least interesting aspect of the API. A simple persistence API like this is useful for applications with simple storage needs that need to store user preferences or simple textual data that is needed by the application. However you aren't going to use this as the data storage platform for applications likeiLike,Flixster orScrabulous.
However I will add that an Atom feed seems like a horrible representation for a list of key<->value pairs. It's so bad that the documentation doesn't provide an example of such a feed.
Hosting OpenSocial Applications
Thedocumentation on hosting OpenSocial applications implies that any site that can host Google gadgets can also host OpenSocial applications. In practice, it means that any site that you can place a