Add note about meaning and interpretation of Content-Type

Author: felipecrv

http/get_compressed/README.md

@@ -82,6 +82,21 @@ If a server adopts this approach and a client does not specify any codecs in
 the `Accept` header, the server can fall back to checking `Accept-Encoding`
 header to pick a compression algorithm for the entire HTTP response stream.
 
+To make debugging easier servers may include the chosen compression codec(s)
+in the `Content-Type` header of the response (quotes are optional):
+
+    Content-Type: application/vnd.apache.arrow.ipc; codecs=zstd
+
+This is not necessary for correct decompression because the payload already
+contains information that tells the IPC reader how to decompress the buffers,
+but it can help developers understand what is going on.
+
+When programatically checking if the `Content-Type` header contains a specific
+format, it is important to use a parser that can handle parameters or look
+only at the media type part of the header. This is not an exclusivity of the
+Arrow IPC format, but a general rule for all media types. For example,
+`application/json; charset=utf-8` should be match `application/json`.
+
 ## HTTP/1.1 Response Compression
 
 HTTP/1.1 offers an elaborate way for clients to specify their preferred

http/get_compressed/python/client/client.py

@@ -34,7 +34,7 @@ def make_request(uri, compression):
     if compression.startswith("identity+"):
         # request IPC buffer compression instead of HTTP compression
         ipc_codec = compression.split("+")[1]
-        headers["Accept"] = f'{ARROW_STREAM_FORMAT};codec="{ipc_codec}"'
+        headers["Accept"] = f'{ARROW_STREAM_FORMAT};codecs="{ipc_codec}"'
     request = urllib.request.Request(uri, headers=headers)
 
     response = urllib.request.urlopen(request)

http/get_compressed/python/server/server.py

@@ -524,7 +524,7 @@ def do_GET(self):
         self.send_header(
             "Content-Type",
             (
-                f"{ARROW_STREAM_FORMAT}; codec={compression[9:]}"
+                f"{ARROW_STREAM_FORMAT}; codecs={compression[9:]}"
                 if compression.startswith("identity+")
                 else ARROW_STREAM_FORMAT
             ),

http/get_simple/python/client/client.py

@@ -25,7 +25,7 @@
 
 response = urllib.request.urlopen('http://localhost:8008')
 content_type = response.headers['Content-Type']
-if content_type != ARROW_STREAM_FORMAT:
+if not content_type.startswith(ARROW_STREAM_FORMAT):
     raise ValueError(f"Expected {ARROW_STREAM_FORMAT}, got {content_type}")
 
 batches = []