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Varnish Author Suggests SPDY Should Be Viewed As a Prototype
An anonymous reader writes "The author of Varnish, Poul-Henning Kamp, has written an interesting critique of SPDY and the other draft protocols trying to become HTTP 2.0. He suggests none of the candidates make the cut. Quoting: 'Overall, I find the design approach taken in SPDY deeply flawed. For instance identifying the standardized HTTP headers, by a 4-byte length and textual name, and then applying a deflate compressor to save bandwidth is totally at odds with the job of HTTP routers which need to quickly extract the Host: header in order to route the traffic, preferably without committing extensive resources to each request. ... It is still unclear for me if or how SPDY can be used on TCP port 80 or if it will need a WKS allocation of its own, which would open a ton of issues with firewalling, filtering and proxying during deployment. (This is one of the things which makes it hard to avoid the feeling that SPDY really wants to do away with all the "middle-men") With my security-analyst hat on, I see a lot of DoS potential in the SPDY protocol, many ways in which the client can make the server expend resources, and foresee a lot of complexity in implementing the server side to mitigate and deflect malicious traffic.'"
Ideally, you give the schema to the other side and they can validate the message before sending to you, catching possible errors there. You validate against same schema on your side as a safety net to week out junk data and messages from users that don't validate. It also allows you to enforce types and limitations on values in a consistent manner.
JSON is good for quick and dirty communications when you are both the sender and the consumer of messages and can be lazy and not care too much about junk data.
Both have their uses, but you have to know when to use which.