Web part as universal data provider
I'd like to make the web part that will be universal data provider. It means that other web parts, including built-in web parts, can use its internal data.
What interface or class that web part should implement or derive from to be universal data provider?
I've made a simple web part that implements IWebPartTable interface and the custom list cannot be populated using that simple web part. Also, I've made another simple web part that implements IWebPartRow interface and the dialog that matches fields from custom list and web part appears, but after I click "Finish" button, the error message about inproper casting comes up.
Could you help me, please, to resolve this issue?
Thank you in advance.