deferred class interface F_ASYNCH_STREAM

feature(s) from F_STREAM
   --  Constant

   Byte_maximum: INTEGER

feature(s) from F_STREAM
   --  Access

   connect
      --  Connect the stream so that it may, if the connect is successful, 
      --  be accessible.

      ensure
         can_fail:  --  success implies is_alive

   imperative_connect
      --  Connect the stream and generate an exception if connection fails.

      ensure
         valid: is_alive

   disconnect
      --  Disconnect a valid stream.

      require
         valid: is_alive
      ensure
         done: not is_alive

feature(s) from F_STREAM
   --  Status

   is_alive: BOOLEAN
      --  Is the stream connection alive (allowing read/write)?


   has_data: BOOLEAN
      --  Is at least one byte waiting to be read?

      require
         valid: is_alive

   has_error: BOOLEAN
      --  Is the stream in an error state?


   is_readable: BOOLEAN
      --  Is the stream currently readable?

      ensure
         asynch: Result implies not is_reading

   is_writable: BOOLEAN
      --  Is the stream currently writable?

      ensure
         asynch: Result implies not is_writing

feature(s) from F_STREAM
   --  Read/write

   last_byte: INTEGER
      --  Last byte read.

      ensure
         byte_size: Result >= 0 and then Result <= Byte_maximum

   read_byte
      --  Read one byte and update last byte.

      require
         valid: is_alive;
         readable: is_readable;
         available: has_data

   write_byte (byte: INTEGER)
      --  Write a byte.

      require
         valid: is_alive;
         writable: is_writable;
         byte_size: byte >= 0 and then byte <= Byte_maximum

feature(s) from F_ASYNCH_STREAM
   --  Status of asynchronous communications

   is_connect_readable: BOOLEAN
      --  Is the stream open in read mode?


   is_connect_writable: BOOLEAN
      --  Is the stream open in write mode?


   is_reading: BOOLEAN
      --  Is a read operation currently under way?


   is_writing: BOOLEAN
      --  Is a write operation currently under way?



end of deferred F_ASYNCH_STREAM