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Design Notes


Design rationale for the Boost.Asio library.

Asynchronous operations

Support for asynchronous operations in the Boost.Asio library is based on the Proactor pattern. This design note outlines the advantages and disadvantages of this approach.

Custom memory allocation

Describes the custom memory allocation support in Boost.Asio.


Examines the buffer abstraction used by asio in order to support scatter-gather operations.

Why EOF is an error

Discusses why the end-of-file condition should be an error code.

Line-based protocols

Outlines Boost.Asio's support for line-based protocols.


An implementation of Boost.Asio for a particular platform may make use of one or more additional threads to emulate asynchronicity. This design note discusses design rules applied to the use of threads in this way.


Describes the "strand" abstraction provided by Boost.Asio to ease concurrent programming and provide scalability across multiple processors.

Platform-specific implementation

This design note lists platform-specific implementation details, such as the default demultiplexing mechanism, the number of threads created internally, and when threads are created.