This document provides an overview of the zembly programming model, including its main building blocks of widgets, data services, and APIs. Widgets are the user interface components, data services provide backend logic, and APIs allow external access. The document describes how widgets and data services interact, how to call services, handle errors and parameters. It also covers logging, keychains, and integrating external web APIs into zembly applications.

1. zembly Programming Model
Srividhya Narayanan, Sr. Engineering Manager
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2. Agenda
• Building Blocks
• Language Reference
• Web APIs
• Building a FB application
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3. Building Blocks
• Widgets
> Are ...
● User interface (rendered in browser)
• Data Services
> Are …
● Back-end logic
• API
> Are …
● Externally available value-added services
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4. Widgets
• Are...
> 3 things – HTML, CSS, JavaScript
> Flavors
● FB: FBML, FBJS
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5. Data Services
• Are...
> JavaScript 1.6 including E4X
> Called from widgets or from other services
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6. API
• Are...
> RESTful services
> WADL(Web Application Description Language)
described
> Called from other widgets and services
> Keyset managed in zembly
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7. Language Reference
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8. Data Services
• Input
// Get value of a parameter
var a = Parameters.param1;
• Output
// Returning a String
return quot;Hello world!quot;;
// Returning an Object
return { foo: quot;barquot; };
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9. Data Services
Calling a service from other service
• Calling zembly created Data service – Using Things
object
var result = Things.codename.serviceName(parameters);
• Calling external Web API - Using Web object
var result = Web.domain.api.serviceName(parameters);
• Passing identity credentials
> From keychain using Owner.keychain
> Generating on the fly
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10. Data Services
Error Occurs when
• Problems with the request or caller, for example, a
required parameter wasn't specified
• Syntax errors in the service code
• JavaScript runtime errors in the service code, such as
reference to undefined variable
• Uncaught errors from a nested service invocation
• Errors thrown from the service code
• Platform errors
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11. Data Services
Error Object
• error.code - Error code returned by the service, or by the
platform. Error code is always included.
• error.message - Message may provide a quot;human
readablequot; information about the error.
• error.details - Details property may carry a structured
information about the error.
• error.httpStatusCode - HTTP status code that was used
in the service response.
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12. Data Services
• Error Handling
> Using try-catch block
> Throwing errors from services
• Logging in Services
> Log.write(message)
> Log.log(message)
> Log.debug
> Log.info
● All these 4 methods currently add a message to the
execution log with info level.
> Log.warn - Adds a message to the execution log with
warning level
> Log.error - Adds a message to the execution log with
error level
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13. Widgets
• Parameters
> As properties of Parameter object:
Parameters.x
> As Markup expressions:
<h1>Hello ${Parameter.name}</h1>
> Markup with a scriptlet
<h1>Hi <?=${Parameter.name}</h1>
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14. Widgets
• Calling a service from a widget
> service invocations from widgets are asynchronous
> Things.callService(serviceName, parameters,
options)
> Web.callService(serviceName, parameters,
options) -
http://zembly.com/things/cb1812d5a786455b82
331045884ca7f9
• Service invocation callbacks
> options.onSuccess : function(data)
> options.onSuccess : function(data, transport,
options)
> Service result comes back in data parameter
> options.onFailure : function(error)
> Error parameter contains the code, message, HTTP status
code and details of the error.
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15. Widgets
• Logging
> Alert()
> Log object
● default logging is turned off when executing
published widgets;
• Keychain
> Not available
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16. Web APIs
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18. API
• Zembly exposed Web APIs
• Bring Your Own API into zembly.
http://wiki.zembly.com/wiki/Bring_Your_Own_API
• NetBeans WADL designer.
http://www.netbeans.org/kb/docs/websvc/wadl-zembly.html
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19. Facebook Demo
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20. Thank You!
srividhya.narayanan@sun.com
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