[Opensim-dev] Thoughts on adding a generic key-value storage system to OpenSim?

[Melanie]

None of our DB layers use the try pattern. Using it at that level 
would be a huge break in an otherwise homogenous interface 
landscape. Also, I don't like the try pattern at all, since it 
always forces the definitnion of a local variable even though the 
result may be needed only once, or only as a truth value.

Melanie

Stefan Andersson wrote:
> John,
> 
> I'm not a big fan of tall/skinny untyped string/string storage, as I believe
> that approach always come back to bite you in the ass in the end. Adam F did
> propose the same thing a year ago, and I was against it then as well.
> 
> Since then, my stance has softened somewhat, as there hasn't really emerged
> any other option than nhibernate (but still, wouldn't that be an option?)
> 
> If you can just turn string GetValue(string context, string key) into 
> 
> bool TryGetValue(string context, string key, out string value)
> 
> embracing the Try pattern, I'm 0 on it.
> 
> I'm presuming that you're going to implement a behind-the-scene
> module-unique identifier also, so modules don't clash on context? I would
> suggest having an IGenericDataStore factory that produces handlers that are
> private to the modules.
> 
> /Stefan
> 
>> -----Original Message-----
>> From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev-
>> bounces at lists.berlios.de] On Behalf Of Hurliman, John
>> Sent: den 21 september 2009 22:05
>> To: opensim-dev at lists.berlios.de
>> Subject: Re: [Opensim-dev] Thoughts on adding a generic key-value
>> storage system to OpenSim?
>> 
>> Formatting got messed up, that should have looked like this:
>> 
>> // returns true if the key was found and data was updated, otherwise
>> false if a new key row was added
>> bool AddOrUpdateKeyValue(string context, string key, string value);
>> 
>> // returns true if the key was found and deleted
>> bool DeleteKeyValue(string context, string key);
>> 
>> // returns the string value if the key was found, otherwise null
>> string GetValue(string context, string key);
>> 
>> -----Original Message-----
>> From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev-
>> bounces at lists.berlios.de] On Behalf Of Hurliman, John
>> Sent: Monday, September 21, 2009 12:54 PM
>> To: opensim-dev at lists.berlios.de
>> Subject: [Opensim-dev] Thoughts on adding a generic key-value storage
>> system to OpenSim?
>> 
>> A lot of the work going into OpenSim recently has been modularizing the
>> codebase and making it easy for third party developers to write
>> plugins. One feature that I think would really complete the picture
>> would be a (simple) generic data storage interface that leveraged the
>> existing OpenSim storage framework. Most plugins I've seen (and wrote)
>> currently tack on their own database tables, use a simple text file
>> with a custom format, or use some other means of data storage that does
>> not match up with the rest of OpenSim. Adding a new database table that
>> had three columns: [context, key, value] would allow plugins to store
>> key/value mappings (string to string) without worrying about data
>> collisions between plugins or having to implement a custom data store
>> every time.
>> 
>> // returns true if the key was found and data was updated, otherwise
>> false if a new key row was added
>> bool AddOrUpdateKeyValue(string context, string key, string value);
>> // returns true if the key was found and deleted
>> bool DeleteKeyValue(string context, string key);
>> // returns the string value if the key was found, otherwise null
>> string GetValue(string context, string key);
>> 
>> Although I've been writing extensions for the OpenSim codebase for
>> quite a while, I'm still fairly new to the guts of the system. Does
>> this seem like the correct solution? If so, where would this interface
>> go? I'm happy to write the code to implement this, I just want feedback
>> from the dev community first to see if I'm on track.
>> 
>> John
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