Subject: [alto] ALTO & HTTP 2

From: Wendy Roome <[email-masked]>
Date: Mon, 02 Feb 2015 13:32:12 -0500

HTTP version 2 is approaching final approval;
http://datatracker.ietf.org/doc/draft-ietf-httpbis-http2/ gives the latest
draft.

What do people think of the HTTP 2 extensions with respect to ALTO?

My take is that while the new features will be wonderful for many
commercial web sites, they have little benefit to ALTO. The only exception
is for server-initiated updates, which could take advantage of the fact
that HTTP 2 officially supports server-push.

But other than that, I don't see how the new HTTP 2 features would help
ALTO. They do not let us provide new services, or let existing services
work more efficiently. Yes, HTTP 2 does provide a better way for a client
to pipeline multiple GETs on a single TCP stream. But it is not that much
better than HTTP 1.1 Keep-Alive, and I doubt that clients will pipeline
many requests anyway. At least not the way a browser does for an
image-heavy page.

What do the rest of you think about ALTO & HTTP 2?

An ALTO client & server can always use HTTP 2, of course. HTTP 2 allows a
client to initiate an 1.1 connection, with an ³I can handle http 2 if you
can² header, and an HTTP 2 aware server can respond with HTTP 2. But that
is transparent to the ALTO protocol specification.

Oh yes, the disadvantages of HTTP 2 are that it is much more complex than
HTTP 1.1, it will be a while before standard HTTP client/server libraries
support it, and any proxies between the client & server must also support
HTTP 2.

	- Wendy Roome

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From: Ben Niven-Jenkins <[email-masked]>
Date: Mon, 2 Feb 2015 20:29:25 +0100

Wendy,

I agree with your analysis below. HTTP/2 provides many advantages over HTTP/1.1 but they do not apply to all use cases and IMO ALTO is one of the use cases where HTTP/2 doesn't provide a significant advantage. The exception to that might be server push as you note but even then I suspect the additional complexity of HTTP/2 probably outweighs the benefit of server push in the ALTO use case given I do not imagine that really timely updates of ALTO information is that critical to most ALTO clients (& clients that really require rapid updates can always make regular revalidation requests to the ALTO server). 

Ben

> On 2 Feb 2015, at 19:32, Wendy Roome <[email-masked]> wrote:
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