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WsPullBytes function (webservices.h)

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Sets up a callback to be invoked to obtain the bytes to be written within an element.
In some encodings this can be more efficient by eliminating a copy of the data.

Syntax

HRESULT WsPullBytes(
  [in]           WS_XML_WRITER          *writer,
  [in]           WS_PULL_BYTES_CALLBACK callback,
  [in, optional] void                   *callbackState,
  [in, optional] WS_ERROR               *error
);

Parameters

[in] writer

The writer to which the bytes will be written.

[in] callback

The callback to invoke when its time to write the binary data.

[in, optional] callbackState

User-defined state to be passed to the callback.

[in, optional] error

Specifies where additional error information should be stored if the function fails.

Return value

This function can return one of these values.

Return code Description
E_INVALIDARG
 One or more arguments are invalid.
WS_E_INVALID_OPERATION
 The operation is not allowed due to the current state of the object.
WS_E_QUOTA_EXCEEDED
 A quota was exceeded.

Remarks

WsWriteBytes and WsPushBytes require the buffer of data to be provided to the writer. In some usage patterns, this may require an extra copy of the data. For those scenarios, WsPullBytes offers a way to request the writer to provide the buffer that must be filled with data.

If the encoding cannot take advantage of this behavior, then WsPullBytes will invoke the callback immediately and operate as if WsWriteBytes was called on the resulting data.

Requirements

Requirement Value
Minimum supported client Windows 7 [desktop apps | UWP apps]
Minimum supported server Windows Server 2008 R2 [desktop apps | UWP apps]
Target Platform Windows
Header webservices.h
Library WebServices.lib
DLL WebServices.dll