Returning a stream of documents for each request

The user's view

• Upon requesting a page, a user should receive some version of that page as quickly as possible
• As fresher versions arrive, the page should be updated in the user's Web browser (perhaps with some dialog box asking whether to really display a newer version)
• The user should always have a clear indication of the staleness of pages being viewed
• A user who is looking at an expired page should be given a very clear warning to this effect

Implementation

• Netscape's server push mechanism is already adequate for displaying successive versions of a document
• Every HTTP GET or conditional GET may return a stream of document versions, each with its own Date: and Last-Modified: headers
• A document body in the stream may be null, indicating that the previous document in the stream was still valid at a date later than previously realized
• A null document may arrive before a non-null document only if the GET request was conditional