[Registry-dev] Typed properties [was: Suggested Registry changes/improvements]

[Jonathan Marsh]

+1 to the first approach.  See below:

Jonathan Marsh - http://www.wso2.com - http://auburnmarshes.spaces.live.com
 

> -----Original Message-----
> From: registry-dev-bounces at wso2.org [mailto:registry-dev-
> bounces at wso2.org] On Behalf Of Chathura C. Ekanayake
> Sent: Thursday, November 08, 2007 9:53 AM
> To: registry-dev at wso2.org
> Subject: [Registry-dev] Suggested Registry changes/improvements
> 
> 
> Below are the changes and improvements suggested in the discussion with
> Glen and Jonathan.
> 
...

> 3) Properties with arbitrary content
> 
> Currently properties of resources can only store strings as their
> values. Glen suggests that we should be able to associate any arbitrary
> content with resources as properties. There are two possible ways to do
> that. One method is to change the data model of the registry, so that
> we
> can store blobs as resource properties. Then we can associate a media
> type with properties to specify whether it is a string or binary
> content.

I like the approach of having a properties with names, values, and media
types.  Simple, clean, very powerful, and allows us to do some nice things
to display the property in the UI: e.g. a JPEG can show a preview and an
upload button to change it, a simple string can be displayed directly with
an inline edit field for quick entry, and XML document might link to an XML
editing view, an HTML document might link to a rich text editor, etc.

I also think we might want to define a couple of our own special "media
types" for this, such as a simple length-limited string from a text/plain
resource, a url, or an epr.  The UI could adapt intelligently to the user's
intention if we had these types along with the traditional media types.

> Second method is to store the content of the property as a normal
> resource in the registry and store the URL of that resource as the
> property value. Then, when ever we look up a property we should
> determine whether it is a string or a URL. If it is URL, we should get
> the content of the corresponding resource and return it as the property
> value. This look up functionality can either be implemented in the
> registry or in the product that uses arbitrary property contents. This
> method does not require changes in the registry data model.

I don't like this.  If it's a normal resource, we should allow comments,
tags, ratings, children, etc.  What's then the point then of distinguishing
the "property" children of a resource from the "resource" children of the
resource?  And you'd still need a type mechanism to differentiate from
simple string properties and paths, which is equal in complexity to the
first option.

> Comments...
> 
> Thanks,
> Chathura
> 
> 
> 
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