2. Boost Beast Translation (zh_Hans)
3. Doc / Qbk / 05 Http Examples / Http Examples (qbk)
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5. Zen

4 string ID 20
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Sophisticated servers may wish to defer the choice of the Body template type until after the header is available. Then, a body type may be chosen depending on the header contents. For example, depending on the verb, target path, or target query parameters. To accomplish this, a parser is declared to read in the header only, using a trivial body type such as [link beast.ref.boost__beast__http__empty_body `empty_body`]. Then, a new parser is constructed from this existing parser where the body type is conditionally determined by information from the header or elsewhere. 574/10000 · 574
5 string ID 29
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — This example illustrates how a server may make the commitment of a body type depending on the method verb: 106/10000 · 106
6 string ID 38
	Source string description type: section title
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Expect 100-continue (Client) __example__ 40/10000 · 40
7 string ID 40
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The Expect field with the value "100-continue" in a request is special. It indicates that the after sending the message header, a client desires an immediate informational response before sending the message body, which presumably may be expensive to compute or large. This behavior is described in [@https://tools.ietf.org/html/rfc7231#section-5.1.1 rfc7231 section 5.1.1]. Invoking the 100-continue behavior is implemented easily in a client by constructing a __serializer__ to send the header first, then receiving the server response, and finally conditionally send the body using the same serializer instance. A synchronous, simplified version (no timeout) of this client action looks like this: 700/10000 · 700
8 string ID 57
	Source string description type: section title
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Expect 100-continue (Server) __example__ 40/10000 · 40
9 string ID 59
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The Expect field with the value "100-continue" in a request is special. It indicates that the after sending the message header, a client desires an immediate informational response before sending the message body, which presumably may be expensive to compute or large. This behavior is described in [@https://tools.ietf.org/html/rfc7231#section-5.1.1 rfc7231 section 5.1.1]. Handling the Expect field can be implemented easily in a server by constructing a __parser__ to read the header first, then send an informational HTTP response, and finally read the body using the same parser instance. A synchronous version of this server action looks like this: 654/10000 · 654
10 string ID 75
	Source string description type: section title
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — HEAD request (Client) __example__ 33/10000 · 33
11 string ID 77
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The [@https://tools.ietf.org/html/rfc7231#section-4.3.2 HEAD request] method indicates to the server that the client wishes to receive the entire header that would be delivered if the method was GET, except that the body is omitted. When a client wishes to receive the response to a HEAD request, it is necessary to inform the parser not to expect a body. This is done by calling [link beast.ref.boost__beast__http__basic_parser.skip `basic_parser::skip`] with the value `true`, as shown in this example: 504/10000 · 504
12 string ID 93
	Source string description type: section title
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — HEAD response (Server) __example__ 34/10000 · 34
13 string ID 95
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — When a server receives a [@https://tools.ietf.org/html/rfc7231#section-4.3.2 HEAD request], the response should contain the entire header that would be delivered if the method was GET, except that the body is omitted. 217/10000 · 217
14 string ID 106
	Source string description type: section title
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — HTTP Relay __example__ 22/10000 · 22
15 string ID 108
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — An HTTP proxy acts as a relay between client and server. The proxy reads a request from the client and sends it to the server, possibly adjusting some of the headers and representation of the body along the way. Then, the proxy reads a response from the server and sends it back to the client, also with the possibility of changing the headers and body representation. 368/10000 · 368
16 string ID 114
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The example that follows implements a synchronous HTTP relay. It uses a fixed size buffer, to avoid reading in the entire body so that the upstream connection sees a header without unnecessary latency. This example brings together all of the concepts discussed so far, it uses both a __serializer__ and a __parser__ to achieve its goal: 336/10000 · 336
17 string ID 126
	Source string description type: section title
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Send Child Process Output __example__ 37/10000 · 37
18 string ID 128
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Sometimes it is necessary to send a message whose body is not conveniently described by a single container. For example, when implementing an HTTP relay function a robust implementation needs to present body buffers individually as they become available from the downstream host. These buffers should be fixed in size, otherwise creating the unnecessary and inefficient burden of reading the complete message body before forwarding it to the upstream host. 457/10000 · 457
19 string ID 135
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — To enable these use-cases, the body type __buffer_body__ is provided. This body uses a caller-provided pointer and size instead of an owned container. To use this body, instantiate an instance of the serializer and fill in the pointer and size fields before calling a stream write function. 290/10000 · 290
20 string ID 140
	Source string description type: paragraph
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — This example reads from a child process and sends the output back in an HTTP response. The output of the process is sent as it becomes available: 145/10000 · 145
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