Skip to content
New issue

Have a question about this project? # for a free GitHub account to open an issue and contact its maintainers and the community.

#

By clicking “#”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? # to your account

Intent is to make all headers list-based. #369

Closed
wants to merge 1 commit into from
Closed

Intent is to make all headers list-based. #369

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
32 changes: 19 additions & 13 deletions draft-ietf-httpbis-semantics-latest.xml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1167,7 +1167,7 @@ Content-Type: text/plain
<t>
<iref item="field value"/>
Each field name present in a section has a corresponding "<x:dfn>field value</x:dfn>"
for that section, composed from all field line values with that given
for that section. A field value is a list whose members are composed from all field line values with that given
field name in that section, concatenated together and separated with
commas. See <xref target="field.order"/> for further discussion of the
semantics of field ordering and combination in messages, and <xref
Expand Down Expand Up @@ -1406,7 +1406,10 @@ deployed and not likely to be registered in a timely manner otherwise.</t>
<x:anchor-alias value="field-vchar"/>

<t>
HTTP field values typically have their syntax defined using ABNF
HTTP field values are comma-separated lists, with zero to many members.
</t>
<t>
Typically, their syntax is defined using ABNF
(<xref target="RFC5234"/>), using the extension defined in <xref target="abnf.extension"/>
as necessary, and are usually constrained to the range of US-ASCII characters.
Fields needing a greater range of characters can use an encoding
Expand Down Expand Up @@ -1436,20 +1439,25 @@ deployed and not likely to be registered in a timely manner otherwise.</t>
as quoted-string (<xref target="quoted.strings"/>).
</t>
<t>
Because commas (",") are used as a generic delimiter between members of a
list-based field value, they need to be treated with care if they are
Because commas (",") are used as a delimiter between members of a
field value, they need to be treated with care if they are
allowed as data within those members. Typically, list members that might contain a
comma are enclosed in a quoted-string.
</t>
<t>
For example, a textual date and a URI (either of which might contain a comma)
could be safely carried in list-based field values like these:
could be safely carried in field values like these:
</t>
<artwork type="example">
Example-URI-Field: "http://example.com/a.html,foo",
"http://without-a-comma.example.com/"
Example-Date-Field: "Sat, 04 May 1996", "Wed, 14 Sep 2005"
Example-Date-Field: "Sat, 04 May 1996"
</artwork>
<t>
Even field values that are intended to carry a single member are considered
to be lists by generic HTTP implementations; as a result, field definitions
need to disambiguate how to handle multiple values when they are received.
</t>
<t>
Note that double-quote delimiters almost always are used with the
quoted-string production; using a different syntax inside double-quotes
Expand Down Expand Up @@ -1598,7 +1606,7 @@ deployed and not likely to be registered in a timely manner otherwise.</t>
<section title="ABNF List Extension: #rule" anchor="abnf.extension">
<t>
A #rule extension to the ABNF rules of <xref target="RFC5234"/> is used to
improve readability in the definitions of some list-based field values.
improve readability in the definitions of field values.
</t>
<t>
A construct "#" is defined, similar to "*", for defining comma-delimited
Expand Down Expand Up @@ -1781,15 +1789,13 @@ deployed and not likely to be registered in a timely manner otherwise.</t>
</t>
<ul>
<li>
<t>Whether the field is a single value or whether it can be a list
(delimited by commas; see <xref target="field.values"/>).</t>
<t>If it is not a list, document how to treat messages
where the field occurs multiple times (a sensible default would
<t>If only a single value is intended to be conveyed, document how to handle messages
where the field value has multiple members (a sensible default would
be to ignore the field, but this might not always be the right
choice).</t>
<t>Note that intermediaries and software libraries might combine
multiple field instances into a single one, despite the
field's definition not allowing the list syntax. A robust format enables
multiple field lines into a single one, despite the
field's definition not allowing multiple members. A robust format enables
recipients to discover these situations (good example: "Content-Type",
as the comma can only appear inside quoted strings;
bad example: "Location", as a comma can occur inside a URI).</t>
Expand Down