I'm still working with the protocol-buffers code in (planet
murphy/protobuf). I want the web server to return a deserialized protocol
buffer struct, then have the client deserialize it. I cannot make this
work, and the problem is clearly due to the data being mangled by
retrieving it from the HTTP port. How can I send binary data in an HTTP
response and retrieve it on the other end without it being modified on the
way?
This is how the original request is made:
(define p
(post-impure-port
(string->url "http://localhost:25678/file-chunk-info";)
(serialize-pbuf proto-buff-struct)))
Here's the function that generates the response:
(define/contract (send-response-pbuf msg-func thk)
(->* (procedure? (-> any)) () response?)
(define msg-name (symbol->string (object-name msg-func)))
(response/xexpr `(html (body (p ,(~a msg-name " processed"))))
#:mime-type (string->bytes/utf-8
"application/octet-stream")
#:headers (list
(header #"Transfer-Encoding"
#"identity")
(header #"Content-Encoding"
#"identity")
(header #"X-protocol-buffer-response"
(serialize-pbuf (thk))))))
Here's what I've tried, none of which worked
*) Basics
- Verifying that the data arrives on the server intact. It does.
- Verifying that (deserialize (serialize x)) works. It does.
- Verifying that putting the data into a manually-constructed (response)
struct, then pulling it out and deserializing it works. It does.
*) Headers on the response
- Setting Content-Type to application/octet-stream
- Setting Transfer-Encoding to identity
- Setting Content-Encoding to identity
*) Retrieving the data client side through the post-impure-port
- Pull the data out with (hash-ref (heads-string->dict (port->string p))
'X-my-custom-header)
- Parse the data manually using regexp-match against (port->bytes p)
- Retrieve the data with (port->bytes-lines p) and deserialize the
individual
The error it's failing with is "<x> does not match expected data type",
which means "you've given me a blob of bytes that cannot be parsed into the
structure that you want me to parse them into."
It only fails on protocol-buffer types that have embedded protocol-buffer
messages, for what that's worth.
This would be trivial if I could get the original response object before it
was turned into a port, but I don't see how to do that.
I am absolutely at my wits end, and I know this has to be simple. What am
I missing?
Dave
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