boostorg/beast
1
0
Fork 1
mirror of https://github.com/boostorg/beast.git synced 2025-07-29 20:37:31 +02:00
Code Issues Packages Projects Releases Wiki Activity

Documentation tidying

Browse Source 
fix #836
This commit is contained in:
Vinnie Falco
2017-10-26 16:05:50 -07:00
parent c3367e0746
commit b5389ba5f2
20 changed files with 117 additions and 149 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
CHANGELOG.md
View File

@ -1,6 +1,7 @@
Version 129:
* Add autobahn test report to doc
* Documentation tidying
--------------------------------------------------------------------------------

10
doc/qbk/00_main.qbk
View File

@ -26,7 +26,7 @@
[template indexterm1[term1] '''<indexterm><primary>'''[term1]'''</primary></indexterm>''']
[template indexterm2[term1 term2] '''<indexterm><primary>'''[term1]'''</primary><secondary>'''[term2]'''</secondary></indexterm>''']
[template repo_file[path] '''<ulink url="../../'''[path]'''">'''[path]'''</ulink>''']
[template source_file[path] '''<ulink url="../../'''[path]'''">'''[path]'''</ulink>''']
[template include_file[path][^<'''<ulink url="../../../../'''[path]'''">'''[path]'''</ulink>'''>]]
[def __N3747__ [@http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3747.pdf [*N3747]]]
@ -34,14 +34,19 @@
[def __rfc6455__ [@https://tools.ietf.org/html/rfc6455 rfc6455]]
[def __rfc7230__ [@https://tools.ietf.org/html/rfc7230 rfc7230]]
[def __Asio__ [@boost:/doc/html/boost_asio.html Boost.Asio]]
[def __Asio__ [@boost:/libs/asio/index.html Boost.Asio]]
[def __async_initfn__ [@boost:/doc/html/boost_asio/reference/asynchronous_operations.html initiating function]]
[def __get_associated_allocator__ [@boost:/doc/html/boost_asio/reference/get_associated_allocator.html `get_associated_allocator`]]
[def __get_associated_executor__ [@boost:/doc/html/boost_asio/reference/get_associated_executor.html `get_associated_executor`]]
[def __asio_handler_invoke__ [@boost:/doc/html/boost_asio/reference/asio_handler_invoke.html `asio_handler_invoke`]]
[def __asio_handler_allocate__ [@boost:/doc/html/boost_asio/reference/asio_handler_allocate.html `asio_handler_allocate`]]
[def __io_context__ [@boost:/doc/html/boost_asio/reference/io_context.html `boost::asio::io_context`]]
[def __executor_work_guard__ [@boost:/doc/html/boost_asio/reference/executor_work_guard.html `boost::asio::executor_work_guard`]]
[def __post__ [@boost:/doc/html/boost_asio/reference/post.html `boost::asio::post`]]
[def __socket__ [@boost:/doc/html/boost_asio/reference/ip__tcp/socket.html `boost::asio::ip::tcp::socket`]]
[def __ssl_context__ [@boost:/doc/html/boost_asio/reference/ssl__context.html `boost::asio::ssl::context`]]
[def __ssl_stream__ [@boost:/doc/html/boost_asio/reference/ssl__stream.html `boost::asio::ssl::stream`]]
[def __streambuf__ [@boost:/doc/html/boost_asio/reference/streambuf.html `boost::asio::streambuf`]]
[def __use_future__ [@boost:/doc/html/boost_asio/reference/use_future_t.html `boost::asio::use_future`]]
@ -73,6 +78,7 @@
[def __basic_fields__ [link beast.ref.boost__beast__http__basic_fields `basic_fields`]]
[def __basic_multi_buffer__ [link beast.ref.boost__beast__basic_multi_buffer `basic_multi_buffer`]]
[def __basic_parser__ [link beast.ref.boost__beast__http__basic_parser `basic_parser`]]
[def __bind_handler__ [link beast.ref.boost__beast__bind_handler `bind_handler`]]
[def __buffer_body__ [link beast.ref.boost__beast__http__buffer_body `buffer_body`]]
[def __fields__ [link beast.ref.boost__beast__http__fields `fields`]]
[def __flat_buffer__ [link beast.ref.boost__beast__flat_buffer `flat_buffer`]]

23
doc/qbk/01_intro.qbk
View File

@ -27,8 +27,9 @@ This library is designed for:
* [*Basis for Further Abstraction.] Components are well-suited for building upon.
Beast is not an HTTP client or HTTP server, but it can be used to build
those things.
This library is not a client or server, but it can be used to build those
things. Many examples are provided, including clients and servers, which may
be used as a starting point for writing your own program.
[heading Motivation]
@ -60,11 +61,11 @@ Supported compilers: msvc-14+, gcc 4.8+, clang 3.6+
Sources are [*header-only].
To link a program using Beast successfully, add the
[@http://www.boost.org/libs/system/doc/reference.html Boost.System]
[@boost:/libs/system/index.html Boost.System]
library to your build scripts. If you use coroutines you'll also need the
[@http://www.boost.org/libs/coroutine/doc/html/index.html Boost.Coroutine]
[@boost:/libs/coroutine/index.html Boost.Coroutine]
library. Please visit the
[@http://www.boost.org/doc/ Boost documentation]
[@boost:/more/getting_started.html Boost documentation]
for instructions on how to do this for your particular build system.
[heading Credits]
@ -102,7 +103,9 @@ for tirelessly answering questions on
[section WebSocket]
The Autobahn|Testsuite provides a fully automated test suite to
The
[@https://github.com/crossbario/autobahn-testsuite Autobahn WebSockets Testsuite]
provides a fully automated test suite to
verify client and server implementations of The WebSocket Protocol
for specification conformance and implementation robustness.
The test suite will check an implementation by doing basic
@ -114,16 +117,14 @@ contains over 500 test cases.
[@https://vinniefalco.github.io/boost/beast/reports/autobahn/index.html Autobahn|Testsuite WebSocket Results]
[warning
Version 0.7.6 of
[@https://github.com/crossbario/autobahn-testsuite Autobahn WebSockets Testsuite]
contains a
Version 0.7.6 of Autobahn|Testsuite contains a
[@https://github.com/crossbario/autobahn-testsuite/issues/77 known defect]
which causes false positives for the following test cases:
which causes false positive failures in Beast for the following test cases:
{ 12.4.5, 12.4.6, 12.4.8, 12.4.9, 12.4.10, 12.4.11, 12.4.13,
12.4.14, 12.4.15, 12.4.16, 12.4.17, 12.4.18 }
When this issue is resolved in the test suite, the reports will be updated.
]
[endsect]
[endsect]

24
doc/qbk/02_examples.qbk
View File

@ -12,13 +12,13 @@
These complete programs are intended to quickly impress upon readers
the flavor of the library. Source code and build scripts for them are
located in the example/ directory.
located in the [source_file example] directory.
[section HTTP Client]
Use HTTP to make a GET request to a website and print the response:
File: [repo_file example/http/client/sync/http_client_sync.cpp]
File: [source_file example/http/client/sync/http_client_sync.cpp]
[example_http_client]
@ -28,7 +28,7 @@ File: [repo_file example/http/client/sync/http_client_sync.cpp]
Establish a WebSocket connection, send a message and receive the reply:
File: [repo_file example/websocket/client/sync/websocket_client_sync.cpp]
File: [source_file example/websocket/client/sync/websocket_client_sync.cpp]
[example_websocket_client]
@ -42,7 +42,7 @@ File: [repo_file example/websocket/client/sync/websocket_client_sync.cpp]
[block'''<?dbhtml stop-chunking?>''']
Source code and build scripts for these programs are located
in the [repo_file example] directory.
in the [source_file example] directory.
@ -203,7 +203,7 @@ listed here along with a description of their use:
[table
[[Source File] [Description]]
[
[[repo_file example/common/detect_ssl.hpp]]
[[source_file example/common/detect_ssl.hpp]]
[
This contains the detect SSL algorithm including the
synchronous and asynchronous initiating functions, described
@ -211,7 +211,7 @@ listed here along with a description of their use:
support both plain and SSL sessions on the same port.
]
][
[[repo_file example/common/root_certificates.hpp]]
[[source_file example/common/root_certificates.hpp]]
[
This contains the root SSL certificates used in the SSL client
examples. These certificates are used to verify the signatures
@ -221,7 +221,7 @@ listed here along with a description of their use:
possible server.
]
][
[[repo_file example/common/server_certificate.hpp]]
[[source_file example/common/server_certificate.hpp]]
[
This file contains a self-signed SSL certificate used by the
SSL server examples. It has not been validated by a Certificate
@ -229,10 +229,10 @@ listed here along with a description of their use:
a browser may generate security warnings.
]
][
[[repo_file example/common/ssl_stream.hpp]]
[[source_file example/common/ssl_stream.hpp]]
[
The `ssl_stream` is a replacement for `boost::asio::ssl::stream`
which supports construction from a moved-froms ocket and is also
The `ssl_stream` is a replacement for __ssl_stream__ which
supports construction from a moved-froms ocket and is also
itself move constructible.
]
]]
@ -247,7 +247,7 @@ Here are all of the example functions and classes presented
throughout the documentation, they can be included and used
in your program without modification
* [repo_file example/doc/http_examples.hpp]
* [source_file example/doc/http_examples.hpp]
[endsect]
@ -261,7 +261,7 @@ operation implementation. This is a complete, runnable version of
the example described in
[link beast.using_io.writing_composed_operations.echo Writing Composed Operations: Echo].
* [repo_file example/echo-op/echo_op.cpp]
* [source_file example/echo-op/echo_op.cpp]
[endsect]

69
doc/qbk/03_core/5_composed.qbk
View File

@ -45,9 +45,8 @@ composed operations:
invoked with no arguments invokes the original completion handler with a
list of bound arguments. The invocation is made from the same implicit
or explicit strand as that which would be used to invoke the original
handler. This is accomplished by using the correct overload of
`asio_handler_invoke` associated with the original completion handler.
handler. This works because the returned call wrapper uses the same
associated executor and associated allocator as the bound handler.
]]
[[
[link beast.ref.boost__beast__handler_ptr `handler_ptr`]
@ -115,54 +114,15 @@ this echo operation:
This is the most important element of writing a composed operation, and
the part which is often neglected or implemented incorrectly. It is the
declaration and definition of the "handler hooks". There are four hooks:
[table Handler Hooks
[[Name][Description]]
[[
[@boost:/doc/html/boost_asio/reference/asio_handler_invoke.html `asio_handler_invoke`]
][
Default invoke function for handlers. This hooking function ensures
that the invoked method used for the final handler is accessible at
each intermediate step.
]]
[[
[@boost:/doc/html/boost_asio/reference/asio_handler_allocate.html `asio_handler_allocate`]
][
Default allocation function for handlers. Implement `asio_handler_allocate`
and `asio_handler_deallocate` for your own handlers to provide custom
allocation for temporary objects.
]]
[[
[@boost:/doc/html/boost_asio/reference/asio_handler_deallocate.html `asio_handler_deallocate`]
][
Default deallocation function for handlers. Implement `asio_handler_allocate`
and `asio_handler_deallocate` for your own handlers to provide custom
allocation for temporary objects.
]]
[[
[@boost:/doc/html/boost_asio/reference/asio_handler_is_continuation.html `asio_handler_is_continuation`]
][
Default continuation function for handlers. Implement
`asio_handler_is_continuation` for your own handlers to indicate when
a handler represents a continuation.
]]
]
forwarding of the final handler's associated allocator and associated
executor to the composed operation.
Our composed operation stores the final handler and performs its own
intermediate asynchronous operations. To ensure that I/O objects, in this
case the stream, are accessed safely it is important to use the same method
to invoke intermediate handlers as that used to invoke the final handler.
Similarly, for the memory allocation hooks our composed operation should use
the same hooks as those used by the final handler. And finally for the
`asio_is_continuation` hook, we want to return `true` for any intermediate
asynchronous operations we perform after the first one, since those represent
continuations. For the first asynchronous operation we perform, the hook should
return `true` only if the final handler also represents a continuation. Our
implementation of the hooks will forward the call to the corresponding
overloads of the final handler:
[example_core_echo_op_6]
case the stream, are accessed safely it is important to use the same
executor to invoke intermediate handlers as that used to invoke the final
handler. Similarly, for memory allocations our composed operation should
use the allocator associated with the final handler.
There are some common mistakes that should be avoided when writing
composed operations:
@ -180,20 +140,17 @@ composed operations:
composed operation. This will cause undefined behavior. For example,
if someone calls the initiating function with a strand-wrapped
function object, and there is more than thread running on the
`io_context`, the underlying stream may be accessed in a fashion
__io_context__, the underlying stream may be accessed in a fashion
that violates safety guarantees.
* For operations which complete immediately (i.e. without calling an
intermediate initiating function), forgetting to use
[@boost:/doc/html/boost_asio/reference/post.html `boost::asio::post`]
to invoke the final handler. This breaks the following initiating
intermediate initiating function), forgetting to use __post__ to
invoke the final handler. This breaks the following initiating
function guarantee: ['Regardless of whether the asynchronous operation
completes immediately or not, the handler will not be invoked from
within this function. Invocation of the handler will be performed
in a manner equivalent to using `boost::asio::post`].
The function
[link beast.ref.boost__beast__bind_handler `bind_handler`]
is provided for this purpose.
in a manner equivalent to using __post__]. The function
__bind_handler__ is provided for this purpose.
A complete, runnable version of this example may be found in the examples
directory.

4
doc/qbk/04_http/02_message.qbk
View File

@ -57,8 +57,8 @@ inspection of fields. As per __rfc7230__, a non-case-sensitive comparison
is used for field names. User defined types for fields are possible.
The `Body` type determines the type of the container used to represent the
body as well as the algorithms for transferring buffers to and from the
the container. The library comes with a collection of common body types.
As with fields, user defined body types are possible.
container. The library comes with a collection of common body types. As
with fields, user defined body types are possible.
Sometimes it is desired to only work with a header. Beast provides a single
class template __header__ and some aliases to model HTTP/1 and HTTP/2 headers:

6
doc/qbk/04_http/04_serializer_streams.qbk
View File

@ -14,15 +14,13 @@ at once, such as:
* Send the header first, and the body later.
* Set chunk extensions or trailers using a chunk decorator.
* Send a message incrementally: bounded work in each I/O cycle.
* Use a series of caller-provided buffers to represent the body.
These tasks may be performed by using the serializer stream interfaces.
To use these interfaces, first construct a suitable object with
the message to be sent:
To use these interfaces, first construct an appropriate serializer
from the message to be sent:
[table Serializer
[[Name][Description]]

4
doc/qbk/04_http/06_serializer_buffers.qbk
View File

@ -16,8 +16,8 @@ algorithms on objects whose interface does not conform to __Stream__.
For example, a
[@https://github.com/libuv/libuv *libuv* socket].
The serializer interface is interactive; the caller invokes it repeatedly
to produce buffers until all of the buffers have been generated. Then the
serializer is destroyed.
to produce buffers until all of the serialized octets have been generated.
Then the serializer is destroyed.
To obtain the serialized next buffer sequence, call
[link beast.ref.boost__beast__http__serializer.next `serializer::next`].

4
doc/qbk/04_http/09_custom_body.qbk
View File

@ -70,10 +70,10 @@ the body type as it appears in the message. This can be any type. For
example, a body's value type may specify `std::vector<char>` or even
`std::list<std::string>`. A custom body may even set the value type to
something that is not a container for body octets, such as a
[@http://www.boost.org/libs/filesystem/doc/reference.html#class-path `boost::filesystem::path`].
[@boost:/libs/filesystem/doc/reference.html#class-path `boost::filesystem::path`].
Or, a more structured container may be chosen. This declares a body's
value type as a JSON tree structure produced from a
[@boost:/doc/html/property_tree/parsers.html#property_tree.parsers.json_parser `json_parser`]:
[@boost:/doc/html/property_tree/parsers.html#property_tree.parsers.json_parser `boost::property_tree::json_parser`]:
```
#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>

19
doc/qbk/04_http/10_custom_parsers.qbk
View File

@ -11,13 +11,14 @@
While the parsers included in the library will handle a broad number of
use-cases, the __basic_parser__ interface can be subclassed to implement
custom parsing strategies: the basic parser processes the incoming octets
into elements according to the HTTP/1 protocol specification, while the
derived class decides what to do with those elements. In particular, users
who create exotic containers for [*Fields] may need to also create their
own parser. Custom parsers will work with all of the stream read operations
that work on parsers, as those algorithms use only the basic parser
interface. Some use cases for implementing custom parsers are:
custom strategies for storing parsed results: the basic parser processes
the incoming octets into elements according to the HTTP/1 protocol
specification, while the derived class decides what to do with those
elements. In particular, users who create exotic containers for [*Fields]
may need to also create their own parser. Custom parsers will work with
all of the stream read operations that work on parsers, as those algorithms
use only the basic parser interface. Some use cases for implementing custom
parsers are:
* Inspect incoming header fields and keep or discard them.
@ -25,8 +26,8 @@ interface. Some use cases for implementing custom parsers are:
* Store header data in a user-defined __Fields__ type.
The basic parser uses the Curiously Recurring Template Pattern
([@https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern CRTP]).
The basic parser uses the
[@https://en.wikipedia.org/wiki/Curiously_recurring_template_pattern Curiously Recurring Template Pattern].
To declare your user defined parser, derive it from __basic_parser__.
The interface to the parser is event-driven. Member functions of the derived
class (termed "callbacks" in this context) are invoked with parsed elements

7
doc/qbk/06_websocket/1_streams.qbk
View File

@ -26,9 +26,10 @@ socket's constructor:
[heading Using SSL]
To use WebSockets over SSL, use an instance of the `boost::asio::ssl::stream`
class template as the template type for the stream. The required `io_context`
and `ssl::context` arguments are forwarded to the wrapped stream's constructor:
To use WebSockets over SSL, use an instance of the __ssl_stream__
class template as the template type for the stream. The required
__io_context__ and __ssl_context__ arguments are forwarded to the
wrapped stream's constructor:
[wss_snippet_1]
[wss_snippet_2]

3
doc/qbk/06_websocket/2_connect.qbk
View File

@ -28,7 +28,8 @@ the TCP/IP socket:
[wss_snippet_3]
[note
Examples use synchronous interfaces for clarity of exposition.
Examples use synchronous interfaces for clarity of exposition;
signatures for asynchronous operations are also provided.
]
[endsect]

6
doc/qbk/06_websocket/5_messages.qbk
View File

@ -9,8 +9,8 @@
[section Send and Receive Messages]
Interfaces for transacting messages are structured into a couple of
layers. The highest layer provides ease of use, while lower layers provide
Interfaces for transacting messages are structured into layers. The
highest layer provides ease of use, while lower layers provide
additional control and flexibility. The layers are arranged thusly:
[table
@ -75,7 +75,7 @@ message ahead of time:
* Sending a message that does not fit in memory at once.
* Providing incremental results as they become available.
For these cases, the frame oriented interface may be used. This
For these cases, the partial data oriented interface may be used. This
example reads and echoes a complete message using this interface:
[ws_snippet_16]

6
doc/qbk/06_websocket/8_notes.qbk
View File

@ -65,9 +65,9 @@ However, this code is well-formed:
[ws_snippet_25]
The implementation uses composed asynchronous operations internally;
although some individiual operations can perform both reads and writes,
this behavior is coordinated internally to make sure the underlying stream
The implementation uses composed asynchronous operations; although
some individiual operations can perform both reads and writes, this
behavior is coordinated internally to make sure the underlying stream
is operated in a safe fashion. This allows an asynchronous read operation
to respond to a received ping frame even while a user-initiated call to
asynchronous write is active.

8
doc/qbk/07_concepts/Body.qbk
View File

@ -24,8 +24,8 @@ the algorithms used during parsing and serialization.
In this table:
* `B` is a type meeting the requirements of [*Body].
* `m` is a value of type `message<b, B, F>` where `b` is a `bool` value
and `F` is a type meeting the requirements of [*Fields].
* `m` is a value of type `message<b,B,F>` where `b` is a `bool` value
and `F` is a type meeting the requirements of __Fields__.
[table Valid expressions
[[Expression] [Type] [Semantics, Pre/Post-conditions]]
@ -66,8 +66,8 @@ In this table:
[`std::uint64_t`]
[
This static member function is optional. It returns the payload
size of `body` not including any chunked transfer encoding. The
function shall not exit via an exception.
size of `body` in bytes not including any chunked transfer encoding.
The function shall not exit via an exception.
When this function is present:

4
doc/qbk/07_concepts/BodyReader.qbk
View File

@ -9,7 +9,9 @@
[section:BodyReader BodyReader]
A [*BodyReader] provides an online algorithm to obtain a sequence of zero
A [*BodyReader] provides an
[@https://en.wikipedia.org/wiki/Online_algorithm online algorithm]
to obtain a sequence of zero
or more buffers from a body during serialization. The implementation creates
an instance of this type when needed, and calls into it one or more times to
retrieve buffers holding body octets. The interface of [*BodyReader] is

14
doc/qbk/08_design.qbk
View File

@ -52,6 +52,20 @@ start. Other design goals:
* Allow for customizations, if the user needs it.
The following video presentation was delivered at
[@https://cppcon.org/ CppCon]
in 2016. It provides a light introduction to some of the earliest
interfaces of Beast (which have since changed).
[block'''
<mediaobject>
<videoobject>
<videodata fileref="https://www.youtube.com/embed/uJZgRcvPFwI?rel=0"
align="center" contentwidth="560" contentdepth="315"/>
</videoobject>
</mediaobject>
''']
[include 08_design/1_http_message.qbk]
[include 08_design/2_http_comparison.qbk]
[include 08_design/3_websocket_zaphoyd.qbk]

18
doc/qbk/08_design/1_http_message.qbk
View File

@ -5,10 +5,28 @@
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Official repository: https://github.com/boostorg/beast
<iframe width="560" height="315" src="https://www.youtube.com/embed/WsUnnYEKPnI?rel=0" frameborder="0" allowfullscreen></iframe>
]
[section HTTP Message Container]
The following video presentation was delivered at
[@https://cppcon.org/ CppCon]
in 2017. The presentation provides a simplified explanation of the design
process for the HTTP message container used in Beast. The slides and code
used are available in the
[@https://github.com/vinniefalco/CppCon2017 GitHub repository].
[block'''
<mediaobject>
<videoobject>
<videodata fileref="https://www.youtube.com/embed/WsUnnYEKPnI?rel=0"
align="center" contentwidth="560" contentdepth="315"/>
</videoobject>
</mediaobject>
''']
In this section we describe the problem of modeling HTTP messages and explain
how the library arrived at its solution, with a discussion of the benefits
and drawbacks of the design choices. The goal for creating a message model

34
example/echo-op/echo_op.cpp
View File

@ -145,7 +145,7 @@ public:
// Associated allocator support. This is Asio's system for
// allowing the final completion handler to customize the
// memory allocation strategy used for composed operation
// states. A composed operation needs to use the same allocator
// states. A composed operation should use the same allocator
// as the final handler. These declarations achieve that.
using allocator_type =
@ -172,11 +172,6 @@ public:
p_.handler(), p_->stream.get_executor());
}
// (DEPRECATED)
template<class AsyncStream_, class Handler_>
friend bool asio_handler_is_continuation(
echo_op<AsyncStream_, Handler_>* op);
// The entry point for this handler. This will get called
// as our intermediate operations complete. Definition below.
//
@ -237,33 +232,6 @@ operator()(boost::beast::error_code ec, std::size_t bytes_transferred)
//]
//[example_core_echo_op_6
// Determines if the next asynchronous operation represents a
// continuation of the asynchronous flow of control associated
// with the final handler. If we are past step one, it means
// we have performed an asynchronous operation therefore any
// subsequent operation would represent a continuation.
// Otherwise, we propagate the handler's associated value of
// is_continuation. Getting this right means the implementation
// may schedule the invokation of the invoked functions more
// efficiently.
//
template<class AsyncStream, class Handler>
bool asio_handler_is_continuation(echo_op<AsyncStream, Handler>* op)
{
// This next call is structured to permit argument
// dependent lookup to take effect.
using boost::asio::asio_handler_is_continuation;
// Always use std::addressof to pass the pointer to the handler,
// otherwise an unwanted overload of operator& may be called instead.
return op->p_->step > 1 ||
asio_handler_is_continuation(std::addressof(op->p_.handler()));
}
//]
//[example_core_echo_op_3
template<class AsyncStream, class Handler>

2
include/boost/beast/http/impl/message.ipp
View File

@ -403,7 +403,7 @@ prepare_payload(std::false_type)
this->result() == status::not_modified))
{
if(! n || *n > 0)
// The response body MUST BE empty for this case
// The response body MUST be empty for this case
BOOST_THROW_EXCEPTION(std::invalid_argument{
"invalid response body"});
}