[Yanel-dev] Moving toward the node based repository interface

[Josias Thöny]

Andreas Wuest wrote:
> Hi
> 
> Here's a short summary of what we've discussed today with regard to the 
> node based repository interface.

Thanks a lot for this summary.

> 
> In the long and medium term, we would like to move to a node interface 
> which contains typed properties (we already have that), and a default 
> property (which we don't have yet). On those properties, getType() can 
> be called to enquire for the property's type. If the type is e.g. 
> binary, then getInputStream() should be called to retrieve its value, if 
> the type is character, then getReader(), etc.
> 
> The default property marks one of the properties as kind of "main". A 
> node would also implement the Property interface, whose methods would be 
> used as a shortcut to access the node's default property.
> 
> When creating new nodes, not only should the creation method be 
> parametrised with the distinction between collection and resource, but 
> also with the content type (in case it is a resource). Subsequently, the 
> correct method should be called to set the content of the default 
> property, e.g. getOutputStream() for binary resources, getWriter() for 
> character resources, etc.
> 
> Since this would require some refactoring, we decided to just implement 
> an isBinary() method on the node, in order to be able to decide if 
> getInputStream() or getReader() should be called to read the content's 
> of the resource. 

I'm currently thinking about how to tell the repository whether a new 
node is binary or not. I guess we have to inform the repository right at 
creation time of a new node.
Would it be ok to pass and use the mime-type? The repository would have 
to decide whether a certain mime-type is binary or textual.

Maybe we could enhance the addNode() method as follows:

public Node addNode(String name, int type, String mimeType);
(type would be either collection or resource)

Or should the caller specify explicitely whether it's binary or not:

public Node addNode(String name, int type, boolean isBinary);

Or would it be better to have dedicated methods:

public Node addCollectionNode(String name);
public Node addResourceNode(String name, String mimeType or boolean 
isBinary);

To use the mime-type instead of a boolean isBinary might have some 
advantages. The repository could e.g. store a text/plain document in a 
different way than application/xml.
Moreoever it could be used to index binary documents like pdf or doc 
(although this would not require to specify the mime-type at creation time).
But I'm not sure if it's easy to decide whether a given mime-type is 
binary or textual.

WDYT?

Josias


> The downside of this is that we can only distinguish 
> between character data and binary data, and therefore lose type 
> information, if the repo back-end had provided some (e.g. using an SQL 
> resource, whose values sport much finer-grained type information than 
> only character and binary).
>