MVC naming conventions for JSON actions

Arguably the path names could all be the same. You can examine the Accept header for the mime-type of your client's desired response, and then return an appropriate view based on what you find there:

• application/json: JSON View
• text/xml: XML View
• text/plain, text/html: JSPView

Browsers set this field to HTML; your JSON clients would simply set this field as appropriate.

It's highly unlikely that anyone would be bookmarking a URL that requests JSON so I think that it's not that important to keep the URL as clean. It's also likely to be programmatically generated, not hand entered. Given these, I'd consider adding it as a query parameter.

 /things/list  -- HTML /things/list?format=json  -- JSON 

This won't break your URLs if you do have ID parameters or need other parameters as well. It could also work with POSTs as well as GETs.

/things/1  -- HTML for "thing 1"/things/1?format=json -- JSON for "thing 1"

I use the convention of

/things/list -- HTML/things/_listpage -- AJAX

The rule is that all AJAXed actions/views have a leading underscore. This tells me that they are never called top-level, and usually have no master page associated. In this case, I keep the action under the same controller in order to share any associated logic.

Typically in the list view I would have a

<% RenderAction("_listpage", "things", new {page = ViewData["CURRENT_PAGE"]}); %>