    indexing
    	description: "FTP protocol"
    	legal: "See notice at end of class."
    	status: "See notice at end of class."
    	date: "$Date: 2006-01-22 18:25:44 -0800 (Sun, 22 Jan 2006) $"
    	revision: "$Revision: 56675 $"

    class interface
    	FTP_PROTOCOL

    create
    	make (addr: like address)
    			-- Create protocol.
    			-- (from DATA_RESOURCE)
    		require -- from DATA_RESOURCE
    			address_exists: addr /= Void
    		ensure -- from DATA_RESOURCE
    			address_set: address = addr

    feature -- Access

    	address: FTP_URL
    			-- Associated address

    	bytes_transferred: INTEGER_32
    			-- Number of transferred bytes
    			-- (from NETWORK_RESOURCE)

    	check_instruction: INTEGER_32 is 7
    			-- Exception code for violated check
    			-- (from EXCEP_CONST)

    	class_invariant: INTEGER_32 is 6
    			-- Exception code for violated class invariant
    			-- (from EXCEP_CONST)

    	com_exception: INTEGER_32 is 28
    			-- Exception code for a COM error.
    			-- (from EXCEP_CONST)

    	create_on_deferred: INTEGER_32 is 17
    			-- Create on deferred
    			-- (from EXCEP_CONST)

    	developer_exception: INTEGER_32 is 24
    			-- Exception code for developer exception
    			-- (from EXCEP_CONST)

    	dollar_applied_to_melted_feature: INTEGER_32 is 26
    			-- $ applied to melted feature
    			-- (from EXCEP_CONST)

    	eiffel_runtime_fatal_error: INTEGER_32 is 25
    			-- Eiffel run-time fatal error
    			-- (from EXCEP_CONST)

    	eiffel_runtime_panic: INTEGER_32 is 13
    			-- Eiffel run-time panic
    			-- (from EXCEP_CONST)

    	exception_in_signal_handler: INTEGER_32 is 20
    			-- Exception in signal handler
    			-- (from EXCEP_CONST)

    	external_exception: INTEGER_32 is 18
    			-- Exception code for operating system error
    			-- which does not set the `errno' variable
    			-- (Unix-specific)
    			-- (from EXCEP_CONST)

    	floating_point_exception: INTEGER_32 is 5
    			-- Exception code for floating point exception
    			-- (from EXCEP_CONST)

    	generating_type: STRING_8
    			-- Name of current object's generating type
    			-- (type of which it is a direct instance)
    			-- (from ANY)

    	generator: STRING_8
    			-- Name of current object's generating class
    			-- (base class of the type of which it is a direct instance)
    			-- (from ANY)

    	hash_code: INTEGER_32
    			-- Hash function
    			-- (from DATA_RESOURCE)
    		ensure -- from HASHABLE
    			good_hash_value: Result >= 0

    	incorrect_inspect_value: INTEGER_32 is 9
    			-- Exception code for inspect value which is not one
    			-- of the inspect constants, if there is no Else_part
    			-- (from EXCEP_CONST)

    	io_exception: INTEGER_32 is 21
    			-- Exception code for I/O error
    			-- (from EXCEP_CONST)

    	last_packet: STRING_8
    			-- Last packet read
    			-- (from DATA_RESOURCE)

    	last_packet_size: INTEGER_32
    			-- Size of last packet
    			-- (from NETWORK_RESOURCE)

    	location: STRING_8
    			-- Location of resource
    			-- (from DATA_RESOURCE)
    		require -- from DATA_RESOURCE
    			address_exists: address /= Void

    	loop_invariant: INTEGER_32 is 11
    			-- Exception code for violated loop invariant
    			-- (from EXCEP_CONST)

    	loop_variant: INTEGER_32 is 10
    			-- Exception code for non-decreased loop variant
    			-- (from EXCEP_CONST)

    	mode: INTEGER_32
    			-- Current mode
    			-- (from DATA_RESOURCE)

    	no_more_memory: INTEGER_32 is 2
    			-- Exception code for failed memory allocation
    			-- (from EXCEP_CONST)

    	number_of_codes: INTEGER_32 is 29
    			-- How many codes are there to represent exceptions?
    			-- (from EXCEP_CONST)

    	operating_system_exception: INTEGER_32 is 22
    			-- Exception code for operating system error
    			-- which sets the `errno' variable
    			-- (Unix-specific)
    			-- (from EXCEP_CONST)

    	out_of_memory: INTEGER_32 is 15
    			-- Out of memory (cannot be ignored)
    			-- (from EXCEP_CONST)

    	port: INTEGER_32
    			-- Port used by service
    			-- (from DATA_RESOURCE)
    		ensure -- from DATA_RESOURCE
    			result_non_negative: Result >= 0

    	postcondition: INTEGER_32 is 4
    			-- Exception code for violated postcondition
    			-- (from EXCEP_CONST)

    	precondition: INTEGER_32 is 3
    			-- Exception code for violated precondition
    			-- (from EXCEP_CONST)

    	proxy_host: STRING_8
    			-- Name or address of proxy host
    			-- (from DATA_RESOURCE)
    		require -- from DATA_RESOURCE
    			proxy_supported: is_proxy_supported
    			proxy_used: is_proxy_used
    		ensure -- from DATA_RESOURCE
    			result_not_empty: Result /= Void and then not Result.is_empty

    	proxy_port: INTEGER_32
    			-- Port of proxy
    			-- (from DATA_RESOURCE)
    		require -- from DATA_RESOURCE
    			proxy_supported: is_proxy_supported
    			proxy_used: is_proxy_used
    		ensure -- from DATA_RESOURCE
    			result_non_negative: Result >= 0

    	read_buffer_size: INTEGER_32
    			-- Size of read buffer
    			-- (from NETWORK_RESOURCE)

    	rescue_exception: INTEGER_32 is 14
    			-- Exception code for exception in rescue clause
    			-- (from EXCEP_CONST)

    	resumption_failed: INTEGER_32 is 16
    			-- Resumption failed (retry did not succeed)
    			-- (from EXCEP_CONST)

    	retrieve_exception: INTEGER_32 is 23
    			-- Exception code for retrieval error
    			-- may be raised by `retrieved' in `IO_MEDIUM'.
    			-- (from EXCEP_CONST)

    	routine_failure: INTEGER_32 is 8
    			-- Exception code for failed routine
    			-- (from EXCEP_CONST)

    	runtime_check_exception: INTEGER_32 is 29
    			-- Exception code for runtime check being violated.
    			-- (from EXCEP_CONST)

    	runtime_io_exception: INTEGER_32 is 27
    			-- Exception code for I/O error raised by runtime functions
    			-- such as store/retrieve, file access...
    			-- (from EXCEP_CONST)

    	service: STRING_8
    			-- Name of service
    			-- (from DATA_RESOURCE)

    	signal_exception: INTEGER_32 is 12
    			-- Exception code for operating system signal
    			-- (from EXCEP_CONST)

    	valid_code (c: INTEGER_32): BOOLEAN
    			-- Is `c' a valid code to represent some kind of exceptions?
    			-- (from EXCEP_CONST)

    	void_assigned_to_expanded: INTEGER_32 is 19
    			-- Exception code for assignment of void value
    			-- to expanded entity
    			-- (from EXCEP_CONST)

    	void_call_target: INTEGER_32 is 1
    			-- Exception code for feature applied to void reference
    			-- (from EXCEP_CONST)

    feature -- Measurement

    	count: INTEGER_32
    			-- Size of data resource

    	default_buffer_size: INTEGER_32 is 16384
    			-- Default size of read buffer

    feature -- Comparison

    	frozen deep_equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void
    			-- or attached to isomorphic object structures?
    			-- (from ANY)
    		ensure -- from ANY
    			shallow_implies_deep: standard_equal (some, other) implies Result
    			both_or_none_void: (some = Void) implies (Result = (other = Void))
    			same_type: (Result and (some /= Void)) implies some.same_type (other)
    			symmetric: Result implies deep_equal (other, some)

    	frozen equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void or attached
    			-- to objects considered equal?
    			-- (from ANY)
    		ensure -- from ANY
    			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

    	is_equal (other: like Current): BOOLEAN
    			-- Is resource equal to `other'?
    			-- (from DATA_RESOURCE)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			symmetric: Result implies other.is_equal (Current)
    			consistent: standard_is_equal (other) implies Result

    	frozen standard_equal (some: ANY; other: like arg #1): BOOLEAN
    			-- Are `some' and `other' either both void or attached to
    			-- field-by-field identical objects of the same type?
    			-- Always uses default object comparison criterion.
    			-- (from ANY)
    		ensure -- from ANY
    			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

    	frozen standard_is_equal (other: like Current): BOOLEAN
    			-- Is `other' attached to an object of the same type
    			-- as current object, and field-by-field identical to it?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			same_type: Result implies same_type (other)
    			symmetric: Result implies other.standard_is_equal (Current)

    feature -- Status report

    	address_exists: BOOLEAN
    			-- Does address exists?
    			-- (from NETWORK_RESOURCE)

    	assertion_violation: BOOLEAN
    			-- Is last exception originally due to a violated
    			-- assertion or non-decreasing variant?
    			-- (from EXCEPTIONS)

    	class_name: STRING_8
    			-- Name of the class that includes the recipient
    			-- of original form of last exception
    			-- (from EXCEPTIONS)

    	conforms_to (other: ANY): BOOLEAN
    			-- Does type of current object conform to type
    			-- of `other' (as per Eiffel: The Language, chapter 13)?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void

    	developer_exception_name: STRING_8
    			-- Name of last developer-raised exception
    			-- (from EXCEPTIONS)
    		require -- from EXCEPTIONS
    			applicable: is_developer_exception

    	error: BOOLEAN
    			-- Has an error occurred?
    			-- (from DATA_RESOURCE)

    	error_code: INTEGER_32
    			-- Code of error
    			-- (from DATA_RESOURCE)

    	error_text (code: INTEGER_32): STRING_8
    			-- Textual description of error
    			-- (from DATA_RESOURCE_ERROR_CONSTANTS)
    		require -- from DATA_RESOURCE_ERROR_CONSTANTS
    			positive_code: code > 0

    	exception: INTEGER_32
    			-- Code of last exception that occurred
    			-- (from EXCEPTIONS)

    	exception_trace: STRING_8
    			-- String representation of the exception trace
    			-- (from EXCEPTIONS)

    	has_packet: BOOLEAN
    			-- Is there a packet available in last_packet?
    			-- (from DATA_RESOURCE)

    	is_binary_mode: BOOLEAN
    			-- Is binary transfer mode selected?

    	is_count_valid: BOOLEAN
    			-- Is value in count valid?
    			-- (from NETWORK_RESOURCE)

    	is_developer_exception: BOOLEAN
    			-- Is the last exception originally due to
    			-- a developer exception?
    			-- (from EXCEPTIONS)

    	is_developer_exception_of_name (name: STRING_8): BOOLEAN
    			-- Is the last exception originally due to a developer
    			-- exception of name `name'?
    			-- (from EXCEPTIONS)

    	is_hashable: BOOLEAN
    			-- Are objects of current type hashable?
    			-- (from DATA_RESOURCE)
    		ensure -- from HASHABLE
    			ok_if_not_default: Result implies (Current /= default)

    	is_logged_in: BOOLEAN
    			-- Logged in to a server?

    	is_mode_set: BOOLEAN
    			-- Has resource mode been set?
    			-- (from DATA_RESOURCE)

    	is_open: BOOLEAN
    			-- Is resource open?
    		require -- from  DATA_RESOURCE
    			True

    	is_packet_pending: BOOLEAN
    			-- Can another packet currently be read out?
    			-- (from NETWORK_RESOURCE)

    	is_proxy_supported: BOOLEAN
    			-- Is proxy supported by resource?
    			-- (from DATA_RESOURCE)

    	is_proxy_used: BOOLEAN
    			-- Is a proxy used?
    			-- (from NETWORK_RESOURCE)

    	is_readable: BOOLEAN
    			-- Is it possible to open in read mode currently?
    			-- (from NETWORK_RESOURCE)
    		ensure -- from DATA_RESOURCE
    			mode_unchanged: mode = old mode

    	is_signal: BOOLEAN
    			-- Is last exception originally due to an external
    			-- event (operating system signal)?
    			-- (from EXCEPTIONS)

    	is_system_exception: BOOLEAN
    			-- Is last exception originally due to an
    			-- external event (operating system error)?
    			-- (from EXCEPTIONS)

    	is_writable: BOOLEAN
    			-- Is it possible to open in write mode currently?
    			-- (from NETWORK_RESOURCE)
    		ensure -- from DATA_RESOURCE
    			mode_unchanged: mode = old mode

    	meaning (except: INTEGER_32): STRING_8
    			-- A message in English describing what `except' is
    			-- (from EXCEPTIONS)

    	original_class_name: STRING_8
    			-- Name of the class that includes the recipient
    			-- of original form of last exception
    			-- (from EXCEPTIONS)

    	original_exception: INTEGER_32
    			-- Original code of last exception that triggered
    			-- current exception
    			-- (from EXCEPTIONS)

    	original_recipient_name: STRING_8
    			-- Name of the routine whose execution was
    			-- interrupted by original form of last exception
    			-- (from EXCEPTIONS)

    	original_tag_name: STRING_8
    			-- Assertion tag for original form of last
    			-- assertion violation.
    			-- (from EXCEPTIONS)

    	passive_mode: BOOLEAN
    			-- Is passive mode used?

    	read_mode: BOOLEAN
    			-- Is read mode set?

    	recipient_name: STRING_8
    			-- Name of the routine whose execution was
    			-- interrupted by last exception
    			-- (from EXCEPTIONS)

    	same_type (other: ANY): BOOLEAN
    			-- Is type of current object identical to type of `other'?
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			definition: Result = (conforms_to (other) and other.conforms_to (Current))

    	supports_multiple_transactions: BOOLEAN is True
    			-- Does resource support multiple transactions per connection?
    			-- (Answer: yes)

    	tag_name: STRING_8
    			-- Tag of last violated assertion clause
    			-- (from EXCEPTIONS)

    	timeout: INTEGER_32
    			-- Connection timeout
    			-- (from DATA_RESOURCE)

    	transfer_initiated: BOOLEAN
    			-- Has transfer being initiated.
    			-- (from DATA_RESOURCE)

    	valid_mode (n: INTEGER_32): BOOLEAN
    			-- Is mode `n' valid?

    	write_mode: BOOLEAN
    			-- Is write mode set?

    feature -- Status setting

    	catch (code: INTEGER_32)
    			-- Make sure that any exception of code `code' will be
    			-- caught. This is the default.
    			-- (from EXCEPTIONS)

    	close
    			-- Close.
    		require -- from DATA_RESOURCE
    			open: is_open
    		ensure -- from DATA_RESOURCE
    			closed: not is_open
    			mode_unchanged: mode = old mode
    			no_packet_available: not (has_packet and is_packet_pending)
    		ensure then
    			not_logged_in: not is_logged_in

    	die (code: INTEGER_32)
    			-- Terminate execution with exit status `code',
    			-- without triggering an exception.
    			-- (from EXCEPTIONS)

    	ignore (code: INTEGER_32)
    			-- Make sure that any exception of code `code' will be
    			-- ignored. This is not the default.
    			-- (from EXCEPTIONS)

    	initiate_transfer
    			-- Initiate transfer.
    		require -- from DATA_RESOURCE
    			no_error_occurred: not error
    			mode_set: is_mode_set
    			open: is_open
    			not_initiated: not transfer_initiated
    		ensure -- from DATA_RESOURCE
    			failure_means_error: not transfer_initiated implies error
    		ensure then
    			connection_established: data_socket.is_open_read or data_socket.is_open_write

    	message_on_failure
    			-- Print an exception history table
    			-- in case of failure.
    			-- This is the default.
    			-- (from EXCEPTIONS)

    	no_message_on_failure
    			-- Do not print an exception history table
    			-- in case of failure.
    			-- (from EXCEPTIONS)

    	open
    			-- Open resource.
    		require -- from DATA_RESOURCE
    			no_error_occurred: not error
    			mode_set: is_mode_set
    		ensure -- from DATA_RESOURCE
    			no_packet_available: not (has_packet and is_packet_pending)
    			initiated_flag_reset: not transfer_initiated
    			failure_means_error: not is_open implies error

    	raise (name: STRING_8)
    			-- Raise a developer exception of name `name'.
    			-- (from EXCEPTIONS)

    	raise_retrieval_exception (name: STRING_8)
    			-- Raise a retrieval exception of name `name'.
    			-- (from EXCEPTIONS)

    	reset_error
    			-- Reset error.
    			-- (from DATA_RESOURCE)
    		ensure -- from DATA_RESOURCE
    			error_reset: not error

    	reset_proxy
    			-- Reset proxy information.
    			-- (from DATA_RESOURCE)
    		ensure -- from DATA_RESOURCE
    			proxy_reset: not address.is_proxy_used

    	reuse_connection (other: DATA_RESOURCE)
    			-- Reuse connection of `other'.
    		require -- from DATA_RESOURCE
    			other_exists: other /= Void
    			same_type: same_type (other)
    			supports_multiple_transactions: supports_multiple_transactions and other.supports_multiple_transactions
    			other_opened: other.is_open

    	set_active_mode
    			-- Switch FTP client to active mode.
    		ensure
    			active_mode_set: not passive_mode

    	set_binary_mode
    			-- Set binary transfer mode.
    		ensure
    			binary_mode_set: is_binary_mode

    	set_passive_mode
    			-- Switch FTP client to passive mode.
    		ensure
    			passive_mode_set: passive_mode

    	set_password (pw: STRING_8)
    			-- Set password to `pw'.
    			-- (from DATA_RESOURCE)
    		require -- from DATA_RESOURCE
    			password_accepted: address.is_password_accepted
    			non_empty_password: pw /= Void and then not pw.is_empty

    	set_port (port_no: INTEGER_32)
    			-- Set port number to `port_no'.
    			-- (from DATA_RESOURCE)
    		require -- from DATA_RESOURCE
    			closed: not is_open
    			non_negative_port_number: port_no >= 0
    		ensure -- from DATA_RESOURCE
    			port_set: port = port_no

    	set_proxy (host: STRING_8; port_no: INTEGER_32)
    			-- Set proxy host to `host' and port to `port_no'.
    			-- (from DATA_RESOURCE)
    		require -- from DATA_RESOURCE
    			proxy_supported: is_proxy_supported
    			closed: not is_open
    			non_empty_host: host /= Void and then not host.is_empty
    			host_ok: address.proxy_host_ok (host)
    			non_negative_port: port_no >= 0
    		ensure -- from DATA_RESOURCE
    			proxy_set: address.is_proxy_used

    	set_proxy_information (pi: PROXY_INFORMATION)
    			-- Set proxy information to `pi'.
    			-- (from DATA_RESOURCE)
    		require -- from DATA_RESOURCE
    			proxy_supported: is_proxy_supported
    		ensure -- from DATA_RESOURCE
    			proxy_set: address.is_proxy_used

    	set_read_buffer_size (n: INTEGER_32)
    			-- Set size of read buffer.
    			-- (from NETWORK_RESOURCE)
    		require -- from DATA_RESOURCE
    			size_positive: n > 0
    		ensure -- from DATA_RESOURCE
    			buffer_size_set: read_buffer_size = n

    	set_read_mode
    			-- Set read mode.
    		ensure -- from DATA_RESOURCE
    			read_mode_set: read_mode

    	set_text_mode
    			-- Set ASCII text transfer mode.
    		ensure
    			text_mode_set: not is_binary_mode

    	set_timeout (n: INTEGER_32)
    			-- Set connection timeout to `n'.
    			-- (from DATA_RESOURCE)
    		require -- from DATA_RESOURCE
    			non_negative: n >= 0
    		ensure -- from DATA_RESOURCE
    			timeout_set: timeout = n

    	set_username (un: STRING_8)
    			-- Set username to `un'.
    			-- (from DATA_RESOURCE)
    		require -- from DATA_RESOURCE
    			username_accepted: address.has_username
    			non_empty_username: un /= Void and then not un.is_empty

    	set_write_mode
    			-- Set write mode.
    		ensure -- from DATA_RESOURCE
    			write_mode_set: write_mode

    feature -- Removal

    	dispose
    			-- Clean up resource.
    			-- (from DATA_RESOURCE)

    feature -- Duplication

    	copy (other: like Current)
    			-- Update current object using fields of object attached
    			-- to `other', so as to yield equal objects.
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    			type_identity: same_type (other)
    		ensure -- from ANY
    			is_equal: is_equal (other)

    	frozen deep_copy (other: like Current)
    			-- Effect equivalent to that of:
    			--		copy (`other' . deep_twin)
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    		ensure -- from ANY
    			deep_equal: deep_equal (Current, other)

    	frozen deep_twin: like Current
    			-- New object structure recursively duplicated from Current.
    			-- (from ANY)
    		ensure -- from ANY
    			deep_equal: deep_equal (Current, Result)

    	frozen standard_copy (other: like Current)
    			-- Copy every field of `other' onto corresponding field
    			-- of current object.
    			-- (from ANY)
    		require -- from ANY
    			other_not_void: other /= Void
    			type_identity: same_type (other)
    		ensure -- from ANY
    			is_standard_equal: standard_is_equal (other)

    	frozen standard_twin: like Current
    			-- New object field-by-field identical to `other'.
    			-- Always uses default copying semantics.
    			-- (from ANY)
    		ensure -- from ANY
    			standard_twin_not_void: Result /= Void
    			equal: standard_equal (Result, Current)

    	frozen twin: like Current
    			-- New object equal to `Current'
    			-- twin calls copy; to change copying/twining semantics, redefine copy.
    			-- (from ANY)
    		ensure -- from ANY
    			twin_not_void: Result /= Void
    			is_equal: Result.is_equal (Current)

    feature -- Basic operations

    	frozen default: like Current
    			-- Default value of object's type
    			-- (from ANY)

    	frozen default_pointer: POINTER
    			-- Default value of type `POINTER'
    			-- (Avoid the need to write `p'.default for
    			-- some `p' of type `POINTER'.)
    			-- (from ANY)

    	default_rescue
    			-- Process exception for routines with no Rescue clause.
    			-- (Default: do nothing.)
    			-- (from ANY)

    	frozen do_nothing
    			-- Execute a null action.
    			-- (from ANY)

    feature -- Input

    	read
    			-- Read packet.
    		require -- from DATA_RESOURCE
    			no_error_occurred: not error
    			open: is_open
    			transfer_initated: transfer_initiated
    			readable: is_readable
    			positive_read_buffer_size: read_buffer_size > 0
    			packet_pending: is_packet_pending
    		ensure -- from DATA_RESOURCE
    			packet_received: is_packet_pending implies last_packet_size > 0
    			counter_correct: not error implies bytes_transferred = old bytes_transferred + last_packet_size

    feature -- Output

    	io: STD_FILES
    			-- Handle to standard file setup
    			-- (from ANY)

    	out: STRING_8
    			-- New string containing terse printable representation
    			-- of current object
    			-- Was declared in ANY as synonym of tagged_out.
    			-- (from ANY)

    	print (some: ANY)
    			-- Write terse external representation of `some'
    			-- on standard output.
    			-- (from ANY)

    	put (other: DATA_RESOURCE)
    			-- Write out resource `other'.
    		require -- from DATA_RESOURCE
    			no_error_occurred: not (error and other.error)
    			other_resource_exists: other /= Void
    			resources_open: is_open and other.is_open
    			writable: is_writable
    			transfer_initated: transfer_initiated

    	frozen tagged_out: STRING_8
    			-- New string containing terse printable representation
    			-- of current object
    			-- Was declared in ANY as synonym of out.
    			-- (from ANY)

    feature -- Platform

    	operating_environment: OPERATING_ENVIRONMENT
    			-- Objects available from the operating system
    			-- (from ANY)

    invariant
    		-- from DATA_RESOURCE
    	address_assigned: address /= Void
    	timeout_non_negative: timeout >= 0
    	packet_constraint: not (has_packet xor last_packet /= Void)
    	pending_constraint: is_packet_pending implies (is_open and is_readable and transfer_initiated)
    	error_definition: error = (error_code /= 0)
    	valid_count_constraint: count > 0 implies is_count_valid
    	mode_constraint: is_mode_set = read_mode xor write_mode

    		-- from ANY
    	reflexive_equality: standard_is_equal (Current)
    	reflexive_conformance: conforms_to (Current)

    indexing
    	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
    	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
    	source: "[
    		Eiffel Software
    		356 Storke Road, Goleta, CA 93117 USA
    		Telephone 805-685-1006, Fax 805-685-6869
    		Website http://www.eiffel.com
    		Customer support http://support.eiffel.com
    	]"

    end -- class FTP_PROTOCOL