RIAction Social Applications in the Cloud 20090226
1. Gadgets and Social Applications
With OpenSocial
Vinoaj Vijeyakumaar
Customer Solutions Engineer
Google Southeast Asia
http://friendfeed.com/vinoaj
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Google Confidential and Proprietary
21. First Stop
OpenSocial.org
Also a social network (surprise surprise!)
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22. A day in the life of a social app developer
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23. A day in the life of a social app developer
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24. A day in the life of a social app developer
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25. A day in the life of a social app developer
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26. A day in the life of a social app developer
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27. Gadgets
A gadget spec:
• Is an XML file.
• Defines metadata about an OpenSocial app.
• Is highly cacheable and does not need a high performance server.
Gadgets use existing web standards
• XML to define metadata.
• HTML for markup.
• JavaScript for interactivity.
• CSS for presentation.
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28. Gadgets
Example gadget XML spec:
• Uses HTML to print “Hello World”.
• Colors the text red with CSS.
• Dynamically adjusts the height of the gadget with JavaScript.
<?xml version=quot;1.0quot; encoding=quot;UTF-8quot; ?>
<Module>
<ModulePrefs title=quot;Hello World!quot;>
<Require feature=quot;dynamic-heightquot; />
</ModulePrefs>
<Content type=quot;htmlquot;>
<![CDATA[
<h1>Hello World</h1>
<style type=quot;text/cssquot;>
h1 { color: #dd0000; }
</style>
<script type=quot;text/javascriptquot;>
gadgets.window.adjustHeight();
</script> ]]> </Content></Module>
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29. Gadgets
JavaScript utility functions for gadgets:
•gadgets.io.makeRequest()
Make cross-domain AJAX calls to remote servers.
•gadgets.json.parse() and gadgets.json.stringify()
Native JSON support.
•gadgets.util.escapeString()
Make text safe for display via innerHTML.
•gadgets.util.registerOnLoadHandler()
Execute code when the page is finished loading.
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30. Gadgets
Add extra features to your gadget:
• dynamic-height - Change the size of your gadget in the container.
• views - Navigate between different surfaces of the container.
• skins - Make your gadget change its styles to match the container.
• Containers may offer custom features...
<?xml version=quot;1.0quot; encoding=quot;UTF-8quot; ?>
<Module>
<ModulePrefs title=quot;Hello World!quot;>
<Require feature=quot;dynamic-heightquot; />
</ModulePrefs>
<Content type=quot;htmlquot;>
<![CDATA[ ... ]]>
</Content>
</Module>
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31. Gadgets
<?xml version=quot;1.0quot; encoding=quot;UTF-8quot; ?>
<Module>
<ModulePrefs title=quot;Hello Social!quot;>
<Require feature=quot;opensocial-0.8quot; />
</ModulePrefs>
<Content type=quot;htmlquot;>
<![CDATA[ ... ]]>
</Content>
</Module>
The OpenSocial JavaScript API is a gadget feature, too!
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37. The OpenSocial JavaScript API
Working with people:
• A Collection represents many opensocial.Person objects.
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38. The OpenSocial JavaScript API
Working with data:
• Persistent data gives apps key, value storage directly on the container.
• String only, but conversion to JSON allows for storage of complex
objects.
• Storage per app per user - scales well with growth.
• Ideal for settings, customizations.
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39. The OpenSocial JavaScript API
Working with activities:
• API to post information about what users are doing with your app.
• Many containers have support for images and some HTML.
• Channel to grow your application.
orkut MySpace hi5
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40. The OpenSocial JavaScript API
Post an activity:
function postActivity(text) {
var params = {};
params[opensocial.Activity.Field.TITLE] = text;
var activity = opensocial.newActivity(params);
opensocial.requestCreateActivity(activity,
opensocial.CreateActivityPriority.HIGH, callback);
};
• Assign the activity text to the TITLE field.
• Call opensocial.newActivity() to create a new Activity instance.
• Call opensocial.requestCreateActivity() to post the activity to the
container.
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42. RESTful and RPC protocols
Opens new development models
•Background processing.
•Easier Flash integration.
•Mobile applications.
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43. RESTful and RPC protocols
Communication methods:
• RESTful (Representational State Transfer)
• RPC (Remote Procedure Call)
Formats:
• XML
• JSON
• AtomPub
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44. RESTful and RPC protocols
REST:
• Resources are URLs.
Example - People:
• All people connected to the given user:
/people/{guid}/@all
• All friends of the given user:
/people/{guid}/@friends
• Profile of the given user:
/people/{guid}/@self
• Profile of the authenticated user:
/people/@me/@self
• Supported Person fields:
/people/@supportedFields
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47. RESTful and RPC protocols
Authentication:
• Both protocols use OAuth to identify users and apps.
• Depending on what the application needs to do, it can use two-legged
or three-legged OAuth.
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49. Shindig
Writing a gadget server is difficult:
• Fast changing API - hard to keep up.
• Standardization is hard to get right.
• Costs $ / ¥ / 元 !
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56. Challenges
Cross container development is still tricky:
• Containers may not follow the standard.
• Containers may follow the standard but have different policies.
• Follow best practices: http://tinyurl.com/4nuzll
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57. Challenges
No central directory
• Hard for apps to spread to many containers.
• Apps need to work with different install processes.
• Directory approval requirements vary from container to container.
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