HTTP Request — cpp-netlib v0.13.0

# HTTP Request

This part of the documentation talks about the publicly accessible API of the HTTP Request objects. This section details the Request Concepts requirements, the implemented and required Directives, Modifiers, and Wrappers that work with the HTTP Request objects.

## Request Concepts

There are two generally supported Request Concepts implemented in the library. The first of two is the Normal Client Request Concept and the second is the Pod Server Request Concept.

The Normal Client Request Concept is what the HTTP Client interface requires. All operations performed internally by the HTTP Client abide by the interface required by this concept definition.

The Pod Server Request Concept is as the name suggests what the HTTP Server implementation requires from Request Objects.

Switching on whether the Request concept chooses either of the Normal Client Request Concept or the Pod Server Request Concept is done through the nested `tag` type and whether that tag derives from the root tag `pod`. Simply, if the Request type’s nested `tag` type derives from `boost::network::tags::pod` then it chooses to enforce the Pod Server Request Concept, otherwise it chooses the Normal Client Request Concept.

### Normal Client Request Concept

A type models the Normal Client Request Concept if it models the Message Concept and also supports the following constructs.

Legend

R: | The request type.
r: | An instance of R.
S: | The string type.
s: | An instance of S.
P: | The port type.
p: | An instance of P.

Construct | Result | Description
--- | --- | ---
`R::string_type` | `S` | The nested `string_type` type.
`R::port_type` | `P` | The nested `port_type` type.
`R r(s)` | NA | Construct a Request with an `s` provided. This treats `s` as the URI to where the request is destined for.
`host(request)` | Convertible to `S` | Return the host to where the request is destined for.
`port(request)` | Convertible to `P` | Return the port to where the request is destined for.
`path(request)` | Convertible to `S` | Return the path included in the URI.
`query(request)` | Convertible to `S` | Return the query part of the URI.
`anchor(request)` | Convertible to `S` | Return the anchor part of the URI.
`protocol(request)` | Convertible to `S` | Return the protocol/scheme part of the URI.
`r << uri(s)` | `R&` | Set the URI of the request.
`uri(r, s)` | `void` | Set the URI of the request.

### Pod Server Request Concept

A type models the Pod Server Request Concept if it models the Message Concept and also supports the following constructs.

Legend

R: | The request type.
r: | An instance of R.
S: | The string type.
I: | An unsigned 8 bit integer.
V: | The vector type for headers.

Construct | Result | Description
--- | --- | ---
`R::string_type` | `S` | The nested `string_type` type.
`R::headers_container_type` | `V` | The nested `headers_container_type` type.
`r.source` | `S` | The nested source of the request.
`r.method` | `S` | The method of the request.
`r.destination` | `S` | The destination of the request. This is normally the URI of the request.
`r.version_major` | `I` | The major version number part of the request.
`r.version_minor` | `I` | The minor version number part of the request.
`r.headers` | `V` | The vector of headers.
`r.body` | `S` | The body of the request.

## Directives

This section details the provided directives that are provided by `cpp-netlib`. The section was written to assume that an appropriately constructed request instance is either of the following:

    boost::network::http::basic_request<
      boost::network::http::tags::http_default_8bit_udp_resolve
    > request;

    // or

    boost::network::http::basic_request<
      boost::network::http::tags::http_server
    > request;

The section also assumes that there following using namespace declaration is in effect:

    using namespace boost::network;

Directives are meant to be used in the following manner:

    request << directive(...);

Warning

There are two versions of directives, those that are applicable to messages that support narrow strings (`std::string`) and those that are applicable to messages that support wide strings (`std::wstring`). The `cpp-netlib` implementation still does not convert wide strings into UTF-8 encoded narrow strings. This will be implemented in subsequent library releases.

For now all the implemented directives are listed, even if some of them still do not implement things correctly.

unspecified `source(std::string const & source_)`
  Create a source directive with a `std::string` as a parameter, to be set as the source of the request.
unspecified `source(std::wstring const & source_)`
  Create a source directive with a `std::wstring` as a parameter, to be set as the source of the request.
unspecified `destination(std::string const & source_)`
  Create a destination directive with a `std::string` as a parameter, to be set as the destination of the request.
unspecified `destination(std::wstring const & source_)`
  Create a destination directive with a `std::wstring` as a parameter, to be set as the destination of the request.
unspecified `header(std::string const & name, std::string const & value)`
  Create a header directive that will add the given name and value pair to the headers already associated with the request. In this case the name and values are both `std::string`.
unspecified `header(std::wstring const & name, std::wstring const & value)`
  Create a header directive that will add the given name and value pair to the headers already associated with the request. In this case the name and values are both `std::wstring`.
unspecified `remove_header(std::string const & name)`
  Create a remove_header directive that will remove all the occurences of the given name from the headers already associated with the request. In this case the name of the header is of type `std::string`.
unspecified `remove_header(std::wstring const & name)`
  Create a remove_header directive that will remove all the occurences of the given name from the headers already associated with the request. In this case the name of the header is of type `std::wstring`.
unspecified `body(std::string const & body_)`
  Create a body directive that will set the request’s body to the given parameter. In this case the type of the body is an `std::string`.
unspecified `body(std::wstring const & body_)`
  Create a body directive that will set the request’s body to the given parameter. In this case the type of the body is an `std::wstring`.

## Modifiers

This section details the provided modifiers that are provided by `cpp-netlib`.

`template <class Tag> inline void source(basic_request<Tag> & request, typename string<Tag>::type const & source_)`
  Modifies the source of the given `request`. The type of `source_` is dependent on the `Tag` specialization of `basic_request`.
`template <class Tag> inline void destination(basic_request<Tag> & request, typename string<Tag>::type const & destination_)`
  Modifies the destination of the given `request`. The type of `destination_` is dependent on the `Tag` specialization of `basic_request`.
`template <class Tag> inline void add_header(basic_request<Tag> & request, typename string<Tag>::type const & name, typename string<Tag>::type const & value)`
  Adds a header to the given `request`. The type of the `name` and `value` parameters are dependent on the `Tag` specialization of `basic_request`.
`template <class Tag> inline void remove_header(basic_request<Tag> & request, typename string<Tag>::type const & name)`
  Removes a header from the given `request`. The type of the `name` parameter is dependent on the `Tag` specialization of `basic_request`.
`template <class Tag> inline void clear_headers(basic_request<Tag> & request)`
  Removes all headers from the given `request`.
`template <class Tag> inline void body(basic_request<Tag> & request, typename string<Tag>::type const & body_)`
  Modifies the body of the given `request`. The type of `body_` is dependent on the `Tag` specialization of `basic_request`.

## Wrappers

This section details the provided request wrappers that come with `cpp-netlib`. Wrappers are used to convert a message into a different type, usually providing accessor operations to retrieve just part of the message. This section assumes that the following using namespace directives are in effect:

    using namespace boost::network;
    using namespace boost::network::http;

`template <class Tag>` unspecified `source(basic_request<Tag> const & request)`
  Returns a wrapper convertible to `typename string<Tag>::type` that provides the source of a given request.
`template <class Tag>` unspecified `destination(basic_request<Tag> const & request)`
  Returns a wrapper convertible to `typename string<Tag>::type` that provides the destination of a given request.
`template <class Tag>` unspecified `headers(basic_request<Tag> const & request)`
  Returns a wrapper convertible to `typename headers_range<basic_request<Tag> >::type` or `typename basic_request<Tag>::headers_container_type` that provides the headers of a given request.
`template <class Tag>` unspecified `body(basic_request<Tag> const & request)`
  Returns a wrapper convertible to `typename string<Tag>::type` that provides the body of a given request.