Refget Sequences returning subsequences and choice of 200 vs 206 status code

[jmarshall]

The “Method: get sequence by ID” section says

If a sub-sequence is requested via a Range header, the response must be one of 206 and only contain the specified sub-sequence, be 200 and contain the entire sequence (thus ignoring the Range header), or 303 redirecting the client to where it can retrieve the sequence.

If a sub-sequence is requested, the response must only contain the specified sub-sequence.

The first sentence's 200 response option and the second sentence are not consistent with each other.

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The Response subsection of the same section says

On success and either a whole sequence or sub-sequence is returned the server MUST issue a 200 status code if the entire sequence is returned. A server SHOULD return a 206 status code if a Range header was specified and the request was successful.

The first sentence is mostly incomprehensible. I think what it's trying to say is

When a successful request results in the entire sequence being returned, the server MUST return it with a 200 status code regardless of whether the request was for the whole sequence or a sub-sequence that covers the entire sequence.

However that is not obviously the best approach and it is not very consistent with the second sentence.

[andrewyatz]

The focus of this bit was to cover the following scenarios.

• An implementation can ignore the range header and choose to return the entire sequence. In which case that's a 200 OK
• Understand the header, and return the portion requested resulting in a 206 Partial Content
• Understand the header, and return the entire sequence because that's what was requested resulting in a 200 OK

There is an attempt to distinguish between a request for part of a sequence and the whole sequence

[nsheff]

Here are revised paragraphs:

Paragraph 1 (replacing the current inconsistent text):

If a sub-sequence is requested via a Range header, the server MUST respond with one of the following:

• 206 Partial Content containing only the requested sub-sequence (RECOMMENDED)
• 200 OK containing the entire sequence, thereby ignoring the Range header (allowed but discouraged)
• 303 See Other redirecting the client to where it can retrieve the sequence

Servers that support Range headers SHOULD return 206 with the requested sub-sequence. Servers that do not support Range headers MAY return 200 with the entire sequence.

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Paragraph 2 (Response subsection):

When a request is successful:

• If the server returns the entire sequence and no Range header was specified, the server MUST return 200 OK
• If a Range header was specified and the server returns only the requested sub-sequence, the server MUST return 206 Partial Content
• If a Range header was specified but the server chooses to return the entire sequence (ignoring the Range header), the server MUST return 200 OK
• If a Range header requests the entire sequence (e.g., Range: bytes=0-), the server SHOULD return 206 Partial Content to indicate Range header support, but MAY return 200 OK

Does this clarify things?