PLT v299 (soon to be PLT v300) is different from PLT v208 (its predecessor), and code that
works with v208 needs work in order to work with v299. This 'recipe'
attempts to provide summaries and links regarding the changes -- An upgrade FAQ, if you will.
These are notes made by Doug Orleans after upgrading a substantial block of servlet
code to 299:
Now that I've finally gotten all my servlets to work with v299 again,
here's a list of the changes I ran into that seems to be
un(der)documented. Hopefully this will make it easier for anyone else
who might be planning follow the same path. I already posted about
some of these but I'm collecting them all here in one place for the record.
However, I'm leaving out a few bugs (which I've reported via help-desk),
on the assumption that they'll be fixed before v300 so you won't have
to think about a workaround.
`with-semaphore' in `(lib "thread.ss")' has been removed, but the
new primitive `call-with-sempahore' seems to be the same thing.
There is a note in HISTORY about useless procedures in "thread.ss"
being removed, but it still took me a little while to figure out the
replacement.
`url-query' in `(lib "url.ss" "net")' returns a list of
symbol/string pairs instead of a string or #f. If the query part of
the URI doesn't include an equals sign, the whole query becomes a
symbol mapped to the empty string. `alist->forml-urlencoded' will
convert the alist back to a string, but appends an equals sign if
there is none.
`url-path' in `(lib "url.ss" "net")' returns a list of strings
instead of string or #f. This is alluded to in HISTORY due to the
realization that rfc2396 allows params to be attached to each path
segment of a URI.
`(lib "servlet-helpers.ss" "web-server")' is no longer needed,
because `(lib "servlet-sig.ss" "web-server")' provides all its
symbols. In fact, you can't require both or you'll get duplicate
symbols. This change was announced on this list but it's not in
MzScheme_300.txt or HISTORY.
`request-headers' in `(lib "servlet-sig.ss" "web-server")' is a
list of symbol/bytes pairs instead of symbol/string pairs.
`request-bindings' is still a list of symbol/string pairs.
The `response/full' and `response/incremental' structs have been
moved from `(lib "servlet-sig.ss" "web-server")' to
`(lib "response.ss" "web-server")'. The "mime" field is a bytes
instead of a string. The field accessors and mutators are no longer
provided, i.e. the structs are opaque.
Errors while handling web-server requests are now reported to
stderr. I think the errors are generally innocuous, for example:
tcp-read: error reading (Connection reset by peer; errno=104)
tcp-write: error writing (Broken pipe; errno=32)
tcp-write: error writing (Connection reset by peer; errno=104)
read-request: http input closed abruptly
tcp-addresses: could not get peer address (Transport endpoint is not connected; errno=107)
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