One document matched: draft-ietf-megaco-h248g-00.txt
Media Gateway Control (Megaco) Michael Brown
Internet Draft Peter Blatherwick
Document: draft-ietf-megaco-h248g-00.txt Nortel Networks
Category: Standards Track July 2000
H.248 Annex G (Pre-Decision White Document)
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026 [1].
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1. Abstract
This document reproduces the content of the ITU-T Study Group 16
White Document draft of H.248 Annex G, which is scheduled for
decision in Geneva in November 2000. H.248 Annex G provides
packages for "User Interface Elements and Actions". Specifically,
the packages in Annex G include:
- Display
- Key
- Keypad
- Label key
- Function key
- Indicator
- Soft key
- Ancillary input
This document is submitted for IETF comment prior to ITU-T decision,
in accordance with procedures currently being negotiated between
ITU-T Study Group and ISOC on behalf of the IETF.
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2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC-2119 [2].
3. Introduction
The following packages define a framework for specifying
capabilities associated with user interface elements, such as text
display, keys, dynamically labeled keys, indicators and alphanumeric
input. In addition, specific extension packages for telephone
keypads and telephone function keys are defined.
4. Proposed Packages
4.1 Display Package
PackageID: dis, 0x0014
Version: 1
Extends: None
This package defines properties and signals associated with text
display user interface elements. See Procedures for details of
operation.
4.1.1 Properties
Number of rows
PropertyID: nrows (0x0001)
Description: Maximum number of rows on the display
Type: integer
Defined in: TerminationState.
Characteristics: read only.
Number of columns
PropertyID: ncols (0x0002)
Description: Maximum number of columns on the display
Type: integer
Defined in: TerminationState.
Characteristics: read only.
Supported unicode code pages
PropertyID: cdpgs (0x0003)
Description: a list of supported unicode pages
Type: list of enumerated type
Defined in: TerminationState.
Characteristics: read only.
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Example: if the text display element supports U+2500 ->U+25ff,
U+2600 ->U+26ff and U+2700 -> U+277f, this property would
return "250, 258, 260, 268, 270" in cdpgs.
Unicode page U+0000 -> U+00ff shall be supported in all
implementations.
Cursor row position
PropertyID: cr (0x0004)
Type: integer
Defined in: TerminationState.
Characteristics: read and write:
Cursor column position
PropertyID: cc (0x0005)
Type: integer
Defined in: TerminationState.
Characteristics: read and write.
Note: row and column numbering begin at 0. A display's origin is
row 0, column 0. The origin is at the top left corner
4.1.2 Events
None
4.1.3 Signals
4.1.3.1 Display
SignalID: di (0x0001)
Description: Display text.
Parameters:
Row
ParameterID: r (0x0001)
Type: Integer
Insertion point row, relative to 0,0. Default is current
cursor position.
Column
ParameterID: c (0x0002)
Type: Integer
Insertion point column, relative to 0,0. Default is current
cursor position.
String
ParameterID: str (0x0003)
Type: String
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Default is empty string (moves cursor position).
Attribute
ParameterID: a (0x0004)
Type: enumerated or list of enumerated
Possible values: plain (0x0001), blink (0x0002), invert
(0x0003), underline (0x0004)
Default Value: Plain
4.1.3.2 Clear Display
SignalID: cld, 0x0002
Description:
This signal clears the entire display and resets the current cursor
position to the origin (row 0, column 0).
Parameters: None
4.1.4 Statistics
None
4.1.5 Procedures
Unicode is supported to provide for multiple languages. The Unicode
Standard, Version 2.0 or ISO/IEC 10646-1:1993 [xxx] shall be the
definitive standard intended when the term Unicode is used within
the context of this document. All text display elements shall at
least support the Unicode pages U+0000 -> U+00ff as the basic
character set. All text strings shall be encoded using UTF-8 as
defined in ISO/IEC 10646 AM1 [xxx].
In the Display signal, text will be inserted beginning at the row
and column given in the signal parameters, relative to 0,0. If no
row and column parameters are given, the text will be inserted
starting at the current cursor position. The current cursor
position will always be advanced to the position immediately after
the last character inserted.
Carriage return <Unicode U+000D> is supported in-string, and moves
the text input to the beginning of the next line, clearing the
remainder (if any) of the current line.
Text wrapping is not provided. A string will not word wrap to the
next row. If a string cannot fit into the current row, it will be
truncated without warning.
The attribute parameter applies to all characters contained in the
current signal. If no attribute is provided, plain text will be
displayed. For example, to turn on an attribute in the middle of a
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string, one would send a signal with a beginning sub-string of plain
text, follow by a signal with the desired attribute(s) for the
middle sub-string, and finishing with the signal containing the
remaining sub-string of plain text.
4.2 Key Package
PackageID: key, 0x0015
Version: 1
Extends: none
This package defines the basic behavior of key user interface
elements. Specific key IDs are selected by name (keyid) from the
list of keys. This package does not specify parameter values for
keys.
Intended to be extended by other packages which have key behavior.
4.2.1 Properties
None.
4.2.2 Events
4.2.2.1 keydown
EventID: kd (0x0001)
Detects key was pressed.
EventDescriptor parameters: None.
ObservedEventDescriptor parameters:
Key name
ParameterId: keyid (0x0001)
Type: Enumeration
Possible values: No values are specified in this package.
Extensions to this package add possible values for keyid.
4.2.2.2 keyup
EventID: ku (0x0002)
Detects key up.
EventDescriptor parameters: None.
ObservedEventDescriptor parameters:
Key name
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ParameterId: keyid (0x0001)
Type: Enumeration
Possible values: No possible values are specified in this
package. Extensions to this package would add possible values
for keyid.
Duration
ParameterId: duration (0x0002)
Type: Integer
Units: miliseconds
Description: Key press duration (key down to key up).
4.2.3 Signals
None
4.2.4 Statistics
None
4.2.5 Procedures
None.
4.3 Keypad Package
PackageID: kp, 0x0016
Version: 1
Extends: key version 1
This package defines the keypad user interface element. The keypad
package is used to represent a standard 10 digit key pad plus the
'*', '#', A, B, C, and D keys. Keypad may be used in conjunction
with digit maps, similar to dtmf tone detection package. Keypad
entry can be directed to provide audio and/or display feedback to
other user interface terminations, for example to automatically
provide audible feedback of keypad touches to the user or to
automatically update display.
Additional Keyid values, and mapping to DigitMap symbols (as
described in Megaco/H.248 Protocol, section 7.1.14):
Name Description DigitMap Symbol
k0 (0x0001) Keypad digit 0 `0'
k1 (0x0002) Keypad digit 1 `1'
k2 (0x0003) Keypad digit 2 `2'
k3 (0x0004) Keypad digit 3 `3'
k4 (0x0005) Keypad digit 4 `4'
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k5 (0x0006) Keypad digit 5 `5'
k6 (0x0007) Keypad digit 6 `6'
k7 (0x0008) Keypad digit 7 `7'
k8 (0x0009) Keypad digit 8 `8'
k9 (0x000a) Keypad digit 9 `9'
ks (0x000b) Keypad digit * `E' or `e'
ko (0x000c) Keypad digit # `F' or `f'
kA (0x000d) Keypad digit A `A' or `a'
kB (0x000e) Keypad digit B `B' or `b'
kC (0x000f) Keypad digit C `C' or `c'
kD (0x0010) Keypad digit D `D' or `d'
4.3.1 Properties
None.
4.3.2 Events
4.3.2.1 DigitMap Completion Event
EventID: ce (0x0001)
Generated when a digit map completes as described in Megaco/H.248
Protocol section 7.1.14. Form of this event is identical to its
definition in DTMF Detection Package (dd), Megaco/H.248 Protocol
section E.6.2.
EventsDescriptor parameters:
Digit map processing is activated only if a digit map parameter
is present, specifying a digit map by name or by value. Other
parameters such as a KeepActive flag or embedded Events or
Signals Descriptors may be present.
ObservedEventsDescriptor parameters:
DigitString
ParameterID: ds (0x0001)
Type: String of digit map symbols (possibly empty) returned as
a quotedString.
Possible values: a sequence of the characters "0" through "9",
"A" through "F", and the long duration modifier "Z".
Description: the portion of the current dial string as
described in Megaco/H.248 Protocol section 7.1.14 which matched
part or all of an alternative event sequence specified in the
digit map.
Termination Method
ParameterID: meth (0x0003)
Type: enumeration
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Possible values:
"UM" (0x0001) Unambiguous match
"PM" (0x0002) Partial match, completion by timer
expiry or unmatched event
"FM" (0x0003) Full match, completion by timer expiry
or unmatched event
Description: indicates the reason for generation of the event.
See the procedures in Megaco/H.248 Protocol section 7.1.14.
4.3.3 Signals
None.
4.3.4 Procedures
None.
4.4 Label Key Package
PackageID: labelkey, 0x0017
Version: 1
Extends: key version 1
This package defines the basic behavior of labeled key user
interface elements. Key labels may be used, for example, to provide
information to the MGC regarding pre-configured telephone key
assignments, allowing telephone moves and changes outside the
initial administrative domain without requiring re-configuration of
keys. May also be used to provide static label information on the
telephone user interface, identifying key function to the user
without the need for manual labeling.
Specific keys are addressed by name (keyid) from the list of keys.
This package does not specify parameter values for keys.
Intended to be extended by other packages which have key behavior.
4.4.1 Properties
Key List
Property ID: keylist (0x0001)
Type: String, using the following format
{{keyid, label, label_size}, ...}
Description: Keylist property allows auditing and setting of
keyid/label mapping. Label size is also given. This package
defines syntax only; no specific keys are defined. See derived
packages for the actual keyid lists.
Defined in: TerminationState
Characteristics: read and write
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4.4.2 Events
None.
4.4.3 Signals
None.
4.4.4 Procedures
None.
4.5 Function Key Package
PackageID: kf, 0x0018
Version: 1
Extends: labelkey version 1
Common telephone function keys are defined in this package. This
allows, for example, line keys and other function keys to be
implemented without specific knowledge of the physical layout of the
telephone.
Additional keyid values in keyup and keydown events and keylist
property:
Name Description
kh (0x0011) Hookswitch
kl (0x0012) Hold
kc (0x0013) Conference
kt (0x0014) Transfer
l001 - l999 (0x0015-0x03fb) Set of line keys
f001 - f999 (0x03fc-0x07e2) Set of assignable function keys
4.5.1 Procedures
Function keys may have well known names (keyid) associated with
function, for example "hookswitch", "hold", etc. These well know
names identify the purpose of the particular key on the actual
device. Function keys may also be assigned a label identifier by
the MGC. This approach avoids assumptions and/or the requirement
for application level knowledge of device-specific configuration of
the physical resources to derive intended function of keys.
Function Keys can be co-related with physically associated
Indicators using Function Key keyid and Indicator indid. If the IDs
are identical, the MGC application can safely assume that the key
and indicator are physically (or otherwise) associated on the actual
device. Again, this avoids assumptions and/or the requirement for
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application level knowledge of device-specific layout of the
physical resources. See also the Indicator package (ind).
NOTE: The key sense of hookswitch (keyid=kh) is a special case. Key
up indicates the hookswitch is depressed (i.e. handset is nominally
on hook). Key down indicates the hookswitch is lifted (i.e. handset
is nominally off hook). This allows for sensible use of the
duration parameter in the keyup event which will normally give the
duration the handset was off-hook.
4.6 Indicator Package
PackageID: ind, 0x0019
Version: 1
Extends: None
This package defines the basic behavior of indicator user interface
elements. Specific indicators are addressed by name (indid) from the
list of indicators. Indicators may have well- known names (indid)
associated with function, for example "message waiting", "hold",
"line active", etc. This allows, for example, indicators to be
implemented without specific knowledge of the physical layout of the
telephone.
Intended to be possible to extend by other packages which have
indicator behavior.
4.6.1 Properties
Indicator List
Property ID: indlist (0x0001)
Type: String, using the following format
{{indid, label, label_size}, ...}
Description: Indicator List property allows auditing and
setting of indid/label mapping. Label size is also given. This
package defines syntax only; no specific indicators are
defined. See derived packages for the actual indid lists.
Defined in: TerminationState.
Characteristics: read and write.
4.6.2 Events
None
4.6.3 Signals
4.6.3.1 SetIndactor
SignalID: is (0x0001)
Set indicator state.
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Parameters:
Indicator name
ParameterId: Indid (0x0001)
Type: Enumeration.
Possible values:
Name Description
il (0x0001) Hold
ic (0x0002) Conference
l001-l999 (0x0003- Set of line indicators
0x03f9)
f001-f999 (0x03fa- Set of assignable
0x07e0) function indicators
ir (0x07e1) Ringer/Alerter
indication
im (0x07e2) Message waiting
indicator
Indicator state
ParameterId: state (0x0002)
Type: Enumeration.
Possible values: On (0x0001), off (0x0002), blink (0x0003),
fast_blink (0x0004), slow_blink (0x0005).
Default is off.
4.6.4 Statistics
None
4.6.5 Procedures
Indicators can be co-related with physically associated Function
Keys using Indicator indid and Function Key keyid. If the IDs are
identical, the MGC application can safely assume that the key and
indicator are physically (or otherwise) associated on the actual
device. This avoids assumptions and/or the requirement for
application level knowledge of device-specific layout of the
physical resources. See also the Function Keys package (kf).
4.7 Soft Key Package
PackageID: ks, 0x001a
Version: 1
Extends: labelkey version 1
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Softkeys are a combination of a function key and a display user
interface element, sharing some behavior of each. Softkeys are
intended to be dynamically updated by the MGC, based on the current
state and context of the application controlling the MG. Since the
display aspect and the key aspect are explicitely bound together,
this avoids assumptions and/or the requirement for application level
knowledge of device-specific layout of the physical resources.
See Procedures for details.
4.7.1 Properties
Number of softkeys
PropertyID: nskeys (0x0001)
PropertyType: Integer
Characteristics: read only
Defined in: TerminationState
Description: Maximum number of individual soft keys.
Display size
PropertyID: sz (0x0002)
Type: Integer
Characteristics: read only
Defined in: TerminationState
Description: Maximum number of characters that can be displayed
in each softkey.
Supported unicode code pages
PropertyID: cdpgs (0x0003)
Description: a list of supported unicode pages
Type: list of enumerated type
Defined in: TerminationState.
Characteristics: read only
4.7.2 Signals
4.7.2.1 SetDisplay
SignalID: sd (0x0001)
Description: Set softkey dynamic display content.
Parameters:
keyid
Parameter ID: k (0x0001)
Type: Enumeration
Possible values: sk1-sk999 (0x0001-0x03e7)
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displayContent
Parameter ID: d (0x0002)
Type: String
4.7.3 Procedures
The display aspect is a subset of the Display (dis) package.
Unicode is supported to provide for multiple languages [xxx], and
all SoftKey elements shall at least support the Unicode pages U+0000
-> U+00ff as the basic character set. All text strings shall be
encoded using UTF-8. If a string cannot fit into the display area,
it will be truncated without warning.
The key aspect, including Events and labeling, derives directly from
Label Key and Key packages. Softkey identifiers (keyid) are indexed
1,2...N. N (nskeys) is the maximum number of softkeys supported by
the MG implementation. Refer to the Label Key (labelkey) and Key
(key) packages for further details.
4.8 Ancillary Input Package
PackageID: anci, 0x001b
Version: 1
Extends: none
The ancillary input package is used to enter user alphanumeric
information such as text input or scan data, which is forwarded to
the MGC for processing. The information is presented as a Unicode
character encoded in UTF-8 format [xxx].
4.8.1 Properties
None.
4.8.2 Events
4.8.2.1 Character input
EventID: ch (0x0001)
Description: A character has been input.
EventDescriptor parameters: None
ObservedEventDescriptor parameters:
Input character
ParameterId: id (0x0001)
Type: Character (UTF-8 character)
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4.8.3 Signals
None.
4.8.4 Statistics
None.
4.8.5 Procedures
None.
5. Security Considerations
Security considerations regarding media gateway control are
discussed in section 10 of [3].
6. References
1 Bradner, S., "The Internet Standards Process -- Revision 3", BCP
9, RFC 2026, October 1996.
2 Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
3 ITU-T Recommendation H.248, "Gateway Control Protocol", Geneva,
June 2000. Also to appear as RFC xxxx (currently draft-ietf-
megaco-merged-01.txt).
7. Acknowledgments
This document reflects the work of the TIA (Telecommunications
Industry Association) TR-41.3.4 subcommittee under the leadership of
Phil Holland.
8. Authors' Addresses
C. Michael Brown (editor) Peter Blatherwick (editor)
Nortel Networks Nortel Networks
4008 Chapel Hill Road P.O. Box 3511, Stn C
Research Triangle Park, Ottawa, Ontario,
NC USA 27709 Canada K1Y 4H7
Phone: (919) 991-7767 Phone: (613) 763-7539
Email: Email:
C.Michael.Brown@nortelnetworks.com blather@nortelnetworks.com
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