Custom map marker opening to dynamic content

ZeeForge developed all code for “ZeeGuide™”, an application of the Hex™ platform that provides a “Facebook for neighborhoods”. The location of the owner of a specific ZeeGuide is displayed as a branded marker on an interactive Google map that opens to a “ZeeWindow” in response to a mouse click on the custom marker. The development challenge was to provide end-to-end code that determines and supplies the html content of the ZeeWindow dynamically, based on merchant profile information stored in the database, so that the user sees the most recent custom content supplied and frequently updated by the owner.

In the browser, the "openZeeWindow" method of an instance of ZeeMarker (a Javascript class provided by the browser binding of the Hex framework) is invoked in response to the click handler of the Google marker. The receiver contains an instance of ZeeCommand (another Hex framework class), created during initialization of the receiver, that reifies the AJAX interaction with the server that will ultimately supply the html. This ZeeCommand instance (an application of the "Command Object" software design pattern) holds a reference to the ZeeMarker, the intended method selector for the server operation ("homeWindowHTML" in this example), and a URL for the server that will handle the request (http://red.dev.zeetix.net/zorb/17125/homeWindowHtml?isDirect=true). After validating that the receiver is enabled, the openZeeWindow method invokes the "get" method of the command object. This, in turn, invokes an AJAX exchange with the server and calls the "openInfoWindowHtml" Google Map api method with the result.

On the server, an object broker (supplied by the server binding of Hex and coded in Python) handles the browser request. That request includes the persistent object ID of a receiver ("17125"), a method selector to be invoked ("homeWindowHTML"), and any arguments ("isDirect=true").

The request is ultimately dispatched by the server object broker to the server-side instance of the same object (in this case, a ZeeMarker with objectID of 17125). The object broker retrieves the contents of this object from the persistent object store (implemented in MySql), caching records as needed, and invokes its homeWindowHtml method (written in Python).

Since ZeeMarker is a presentation object, the homeWindowHtml method is delegated to a descendant of ZeePage through presentation logic that identifies the owner of the ZeeMarker, queries a user profile associated with that party, and returns a ZeeWindow descendant (in this case, an instance of PremiumZeeWindow) that displays a ZeeView that ultimately references (through a ZeePage instance kept as an instance variable of the ZeeView) the business data associated with the owner of the ZeeMarker.

Having been dynamically bound to the appropriate ZeePage instance (supplied with the owner of the original ZeeMarker), the homeWindowHtml method is ultimately implemented by an instance of ZeeWindowRenderer (an application of the "Strategy" software design pattern). The ZeeWindowRenderer expands template objects provided by the Hex presentation framework with business data associated with the owner and kept in the persistent object store, and constructs the requested HTML. The careful separation of presentation and business logic maximizes the ability of each to be independently varied, a foundation of mature software design.

The resulting html is then serialized, using a Python implementation of JSON (with a C-language accelerator added to eliminate a major bottleneck identified during earlier benchmarking), and wrapped in an object for delivery to the browser.

This response, received asynchronously by the browser in its AJAX handler, is unwrapped in Javascript and the resulting html is then passed to the openInfoWindowHtml method of the Google API. The desired window then pops up in the interactive map of the user's browser

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