Exit Zen
20
string ID 47
type: table cell
English
These helper functions are used to construct a chunk or last chunk directly at call sites.
90/900 · 90
21
string ID 101
type: paragraph
English
We demonstrate the use of these objects first by declaring a function which returns the next buffer sequence to use as a chunk body:
132/1320 · 132
22
string ID 106
type: paragraph
English
This example demonstrates sending a complete chunked message payload manually. No chunk extensions or trailers are emitted:
123/1230 · 123
23
string ID 111
type: paragraph
English
The following code sends additional chunks, and sets chunk extensions using the helper container. The container automatically quotes values in the serialized output when necessary:
180/1800 · 180
24
string ID 117
type: paragraph
English
Callers can take over the generation and management of the extensions buffer by passing a non-owning string. Note that this requires the string contents to adhere to the correct syntax for chunk extensions, including the needed double quotes for values which contain spaces:
274/2740 · 274
25
string ID 124
type: paragraph
English
The next code sample emits a chunked response which promises two trailer fields and delivers them in the last chunk. The implementation allocates memory using the default or a passed-in allocator to hold the state information required to serialize the trailer:
260/2600 · 260
26
string ID 131
type: paragraph
English
Using a custom allocator to serialize the last chunk:
53/530 · 53
27
string ID 135
type: paragraph
English
Alternatively, callers can take over the generation and lifetime management of the serialized trailer fields by passing in a non-owning string:
143/1430 · 143
28
string ID 141
type: paragraph
English
For the ultimate level of control, a caller can manually compose the chunk itself by first emitting a header with the correct chunk body size, and then by emitting the chunk body in multiple calls to the stream write function. In this case the caller is responsible for also emitting the terminating CRLF (`"\r\n"`):
316/3160 · 316
29
string ID 149
type: heading
English
Parsing Chunks
14/140 · 14
30
string ID 151
type: paragraph
English
The __parser__ automatically removes the chunked transfer coding when it is the last encoding in the list. However, it also discards the chunk extensions and does not provide a way to determine the boundaries between chunks. Advanced applications which need to access the chunk extensions or read complete individual chunks may use a callback interface provided by __parser__:
376/3760 · 376
31
string ID 158
type: table title
English
Chunking Parse Callbacks
24/240 · 24
158
string ID 158
type: table cell
English
Name
4/100 · 4
158
string ID 158
type: table cell
English
Description
11/110 · 11
34
string ID 158
type: table cell
English
[link beast.ref.boost__beast__http__parser.on_chunk_header `on_chunk_header`]
77/770 · 77
35
string ID 158
type: table cell
English
Set a callback to be invoked on each chunk header.

The callback will be invoked once for every chunk in the message payload, as well as once for the last chunk. The invocation happens after the chunk header is available but before any body octets have been parsed.

The extensions are provided in raw, validated form, use [link beast.ref.boost__beast__http__basic_chunk_extensions.parse `chunk_extensions::parse`] to parse the extensions into a structured container for easier access. The implementation type-erases the callback without requiring a dynamic allocation. For this reason, the callback object is passed by a non-constant reference.

The function object will be called with this equivalent signature:
713/7130 · 713
36
string ID 158
type: table cell
English
[link beast.ref.boost__beast__http__parser.on_chunk_body `on_chunk_body`]
73/730 · 73
37
string ID 158
type: table cell
English
Set a callback to be invoked on chunk body data.

The callback will be invoked one or more times to provide buffers corresponding to the chunk body for the current chunk. The callback receives the number of octets remaining in this chunk body including the octets in the buffer provided.

The callback must return the number of octets actually consumed. Any octets not consumed will be presented again in a subsequent invocation of the callback. The implementation type-erases the callback without requiring a dynamic allocation. For this reason, the callback object is passed by a non-constant reference.

The function object will be called with this equivalent signature:
673/6730 · 673
38
string ID 214
type: paragraph
English
This example will read a message header from the stream, and then manually read each chunk. It recognizes the chunk boundaries and outputs the contents of each chunk as it comes in. Any chunk extensions are printed, each extension on its own line. Finally, any trailers promised in the header are printed.
305/3050 · 305
39
string ID 221
type: paragraph
English
Given the HTTP response as input on the left, the output of the function shown above is shown on the right:
107/1070 · 107