RFC 2524
Neda's Efficient Mail Submission and Delivery (EMSD) Protocol Specification Version 1.3
Pages: 83
Informational
Informational
Part 2 of 4 – Pages 11 to 39
3 EFFICIENT MAIL SUBMISSION AND DELIVERY PROTOCOL
EM Submission is the process of transferring a message from EMSD-UA to EMSD-SA. EM Delivery is the process of transferring a message from EMSD-SA to EMSD-UA.
The Message-submission service enables an EMSD-UA to submit a message
to the EMSD-SA for transfer and delivery to one or more recipients.
The Message-submission Service comprises of the submit operation --
invoked by the EMSD-UA -- and possibly the submitVerify operation --
invoked by the EMSD-SA.
The Message-delivery service enables the EMSD-SA to deliver a message
to an EMSD-UA. The Message-delivery Service comprises of the deliver
operation -- invoked by the EMSD-SA -- and possibly the deliverVerify
operation -- invoked by the EMSD-UA.
EMSD-UA uses the following services:
o Message-submission
+---------------------------------------------+
| MTS |
| |
| +-------------------------+ |
| | MRS | |
| | +---+ +---+ | |
| | | | | M | | +---+ |
| | | |<-------->| T |<----------->| | |
| | | | | A | | | | | +---+
| | | | +---+ | | E | | | E |
| | | | | | M | | | M |
| | | M | | | S | | EMSD-P&FS | S |
| | | T |<-------------------------->| D |<---------------->| D |
| | | A | | | - | | | - |
| | | | +---+ | | S | | | U |
| | | | | M | | | A | | | A |
| | | |<-------->| T |<----------->| | | +---+
| | | | | A | | | | |
| | +---+ +---+ | +---+ |
| | | |
| +-------------------------+ |
| |
| |
+---------------------------------------------+
Figure 2: Efficient Mail Submission and Delivery Protocol
o Delivery-control (the deliveryControl operation).
EMSD-SA uses the following services:
o Message-delivery
o Submission-control (the submissionControl operation).
This specification expresses information objects using ASN.1 [X.208].
This specification expresses Remote Operations based on the model of
ESROS as specified in Efficient Short Remote Operations (RFC-2188)
[1]. The ES-OPERATION notation of (RFC-2188) is used throughout this
specification to define specific operations.
This specification uses the Duplicate Operation Detection Support
functions as specified in Section 4.
3.1 Use Of Lower Layers
3.1.1 Use of ESROS
ESRO protocol, as specified in (RFC-2188 [1]), provides reliable
connectionless remote operation services on top of UDP [6] with
minimum overhead. ESRO protocol supports segmentation and
reassembly, concatenation and separation.
ESRO Services (2-Way and 3-Way handshake) shall be used by the EMSD-
P.
ESRO Service Access Point (SAP) selectors used by EMSD-P are
enumerated in the protocol.
3.1.2 Use Of UDP
EMSD-P through ESRO MUST use UDP [6] port number 642 (esro-emsdp).
Note that specification of Service Access Points (SAP) for EMSD-P
include the UDP Port Number specification in addition to ESRO SAP
selector specifications. In other words, EMSD-P's use of ESRO SAPs
does not preclude use of the same SAP selectors by other protocols
which use a UDP port other than port 642. Such usage of ESRO is a
design characteristic of ESRO which results into bandwidth efficiency
and is not a scalability limitation.
3.1.3 Encoding Rules
Use of Basic Encoding Rules (BER) [5] is mandatory for both EMSD
Format Standards and EMSD Protocol.
In order to minimize data transfer, the following restrictions shall
be maintained in the formatting of EMSD PDUs:
o Specifically, when ASN.1 Basic Encoding Rules are being used:
A. Only the "Definite" form of Length encoding MUST be used,
B. The "Short" form of Length encoding MUST be used whenever
possible (i.e. when the Length is less than 128), and
C. OCTET STRING and BIT STRING values, and any other native
ASN.1 types which may be encoded as either "Primitive" or
"Constructed", MUST always be encoded as "Primitive" and
MUST never be "Constructed".
3.1.4 Presentation Context
Parameter Encoding Type of "0" MUST be used in ESRO Protocol to
identify Basic Encoding Rules for operation arguments.
3.2 EMSD-UA Invoked Operations
The following operations are invoked by EMSD-UA:
a. submit
b. deliveryControl
c. deliveryVerify
The submit operation uses the duplication detection functional unit
while deliveryControl and deliveryVerify don't use the duplication
detection.
The complete definition of these operations follows.
3.2.1 submit
The submit ES-OPERATION enables an EMSD-UA to submit a message to the
EMSD-SA for transfer and delivery to one or more recipients.
submit ES-OPERATION
ARGUMENT SubmitArgument
RESULT SubmitResult
ERRORS
{
submissionControlViolated,
securityError,
resourceError,
protocolViolation,
messageError
} ::= 33;
Duplicate operation detection is necessary for this operation.
The successful completion of the ES-OPERATION signifies that the
EMSD-SA has accepted responsibility for the message (but not that it
has delivered it to its intended recipients).
The disruption of the ES-OPERATION by an error signifies that the
EMSD-SA cannot assume responsibility for the message.
Arguments
This operation's arguments are:
SubmitArgument ::= SEQUENCE
{
-- Security features
security [0] IMPLICIT SecurityElement OPTIONAL,
-- Segmentation features for efficient transport
segment-info SegmentInfo OPTIONAL,
-- Content type of the message
content-type ContentType,
--
-- THE CONTENT --
--
-- The submission content
content ANY DEFINED BY content-type
};
The fields are:
Security
See Section 3.4.1, "SecurityElements".
Segment-info
See Section 3.4.2, "Message Segmentation and Reassembly".
Content-type
This argument identifies the type of the content of the message. It
identifies the abstract syntax and the encoding rules used.
Content
This argument contains the information the message is intended to
convey to the recipient(s). It shall be generated by the originator
of the message.
Results
This operation's results are:
SubmitResult ::= SEQUENCE
{
-- Permanent identifier for this message.
-- Also contains the message submission time.
-- See comment regarding assignment of message identifiers,
-- at the definition of EMSDLocalMessageId.
message-id EMSDLocalMessageId
};
The fields are:
Message-id
This result contains an EMSD-SA-identifier that uniquely and
unambiguously identifies the message-submission. It shall be
generated by the EMSD-SA.
Errors
See Section 3.4.3.
3.2.2 deliveryControl
The deliveryControl ES-OPERATION enables the EMSD-UA to temporarily limit the operations that the EMSD-SA may invoke, and the messages that the EMSD-SA may deliver to the EMSD-UA via the Message delivery ES-OPERATION. deliveryControl ES-OPERATION ARGUMENT DeliveryControlArgument RESULT DeliveryControlResult ERRORS { securityError, resourceError, protocolViolation } ::= 2; The duplicate operation detection is not required for this operation. The EMSD-SA shall hold until a later time, rather than abandon, ES- OPERATIONS and messages that are presently suspended. The successful completion of the ES-OPERATION signifies that the specified controls are now in force. The ES-OPERATION returns an indication of any ES-OPERATIONS that the EMSD-SA would invoke, or any message types that the EMSD-SA would deliver, were it not for the prevailing controls. Arguments This operation's arguments are: DeliveryControlArgument ::= SEQUENCE { -- Request an addition of or removal of a set of restrictions restrict [0] IMPLICIT Restrict DEFAULT update, -- Which operations are to be placed in the restriction set permissible-operations [1] IMPLICIT Operations OPTIONAL, -- What maximum content length should be allowed permissible-max-content-length [2] IMPLICIT INTEGER (0..ub-content-length) OPTIONAL,
-- What is the lowest priority message which may be delivered
permissible-lowest-priority
[3] IMPLICIT ENUMERATED
{
non-urgent (0),
normal (1),
urgent (2)
} OPTIONAL,
-- Security features
security [4] IMPLICIT SecurityElement
OPTIONAL,
-- User Feature selection
user-features [5] IMPLICIT OCTET STRING
OPTIONAL
};
Restrict
This argument indicates whether the controls on ES-OPERATIONS are to
be updated or removed. It may be generated by the EMSD-UA.
This argument may have one of the following values:
o update: The other arguments update the prevailing controls;
o remove: All temporary controls are to be removed
In the absence of this argument, the default update shall be assumed.
Permissible-operations
This argument indicates the ES-OPERATIONS that the EMSD-SA may invoke
on the EMSD-UA. It may be generated by the EMSD-UA.
This argument may have the value allowed or prohibited for each of
the following:
o message-delivery: The EMSD-SA may/may not invoke the deliver
ES-OPERATIONS; and
o Other ES-OPERATIONS are not subject to controls, and may be
invoked at any time.
In the absence of this argument, the ES-OPERATIONS that the EMSD-SA may invoke on the EMSD-UA are unchanged. Permissible-max-content-length This argument contains the content-length, in octets, of the longest-content message that the EMSD-SA shall deliver to the EMSD-UA via the deliver ES-OPERATIONS. It may be generated by the EMSD-UA. In the absence of this argument, the permissible-maximum-content- length of a message that the EMSD-SA may deliver to the EMSD-UA is unchanged. Permissible-lowest-priority This argument contains the priority of the lowest priority message that the EMSD-SA shall deliver to the EMSD-UA via the deliver ES- OPERATIONS. It may be generated by the EMSD-UA. This argument may have one of the following values of the priority argument of the submit ES-OPERATIONS: normal, non-urgent or urgent. In the absence of this argument, the priority of the lowest priority message that the EMSD-SA shall deliver to the EMSD-UA is unchanged. Security See Section 3.4.1, "SecurityElements". User-features This argument contains information that allows the EMSD-UA to convey to MTS the feature set that the user is capable of supporting. This argument will be defined when the setConfiguration and getConfiguration operations are defined. Results DeliveryControlResult ::= SEQUENCE { -- Operation types queued at the EMSD-SA due to existing -- restrictions. waiting-operations [0] IMPLICIT Operations DEFAULT { },
-- Types of messages queued at the EMSD-SA due to
-- existing restrictions
waiting-messages [1] IMPLICIT WaitingMessages
DEFAULT { },
-- Content Types of messages queued at the EMSD-SA
waiting-content-types SEQUENCE SIZE (0..ub-content-types) OF
ContentType DEFAULT { }
};
Restrict ::= ENUMERATED
{
update (1),
remove (2)
};
Operations ::= BIT STRING
{
submission (0),
delivery (1)
};
WaitingMessages ::= BIT STRING
{
long-content (0),
low-priority (1)
};
Waiting-operations
This result indicates the ES-OPERATIONS being held by the EMSD-SA,
and that the EMSD-SA would invoke on the EMSD-UA if it were not for
the prevailing controls. It may be generated by the EMSD-SA.
This result may have the value holding or not-holding for each of the
following:
o message-delivery: The EMSD-SA is/is not holding messages, and
would invoke the deliver ES-OPERATIONS on the EMSD-UA if it were
not for the prevailing controls.
In the absence of this result, it may be assumed that the EMSD-SA is
not holding any messages for delivery due to the prevailing controls.
Waiting-messages
This result indicates the kind of messages the EMSD-SA is holding for
delivery to the EMSD-UA, and would deliver via the deliver ES-
OPERATIONS, if it were not for the prevailing controls. It may be
generated by the EMSD-SA.
This result may have one or more of the following values:
o long-content: The EMSD-SA has messages held for delivery to the
EMSD-UA which exceed the permissible maximum-content-length
control currently in force;
o low-priority: The EMSD-SA has messages held for delivery to the
EMSD-UA of a lower priority than the permissible-lowest-priority
control currently in force;
In the absence of this result, it may be assumed that the EMSD-SA is
not holding any messages for delivery to the EMSD-UA due to the
permissible-maximum-content-length, permissible-lowest-priority or
permissible-security context controls currently in force.
Errors
See Section 3.4.3.
3.2.3 deliveryVerify
The deliveryVerify ES-OPERATIONS enables the EMSD-UA to verify
delivery of a message when it receives FAILURE.indication for deliver
ES-OPERATIONS.
deliveryVerify ES-OPERATION
ARGUMENT DeliveryVerifyArgument
RESULT DeliveryVerifyResult
ERRORS
{
verifyError,
resourceError,
protocolViolation
} ::= 5;
The duplicate operation detection is not required for this operation.
Arguments
This operation's arguments are:
DeliveryVerifyArgument ::= SEQUENCE
{
-- Identifier of this message. This is the same identifier that
-- was provided to the originator in the Submission Result.
-- See comment regarding assignment of message identifiers,
-- at the definition of EMSDMessageId.
message-id EMSDMessageId
};
Message-id
This argument contains an EMSD-SA-identifier that distinguishes the
message from all other messages. It shall be generated by the EMSD-
SA, and shall have the same value as the message-submission-
identifier supplied to the originator of the message when the message
was submitted.
Results
DeliveryVerifyResult ::= SEQUENCE
{
status DeliveryStatus
};
DeliveryStatus ::= ENUMERATED
{
no-report-is-sent-out (1),
delivery-report-is-sent-out (2),
non-delivery-report-is-sent-out (3)
};
No-report-is-sent-out
This result indicates that EMSD-SA has received the delivery verify
and no report is sent out (either because it has not been requested
or EMSD-SA has problems and can not send it out).
Delivery-report-is-sent-out
This result indicates that EMSD-SA has received the delivery verify
and has sent the delivery report out. Non-Delivery-report-is-sent-out This result indicates that EMSD-SA has received the delivery verify but it has already sent out a non-Delivery report. This should not happen in normal cases but a wrong user profile on EMSD-SA side can result in this outcome. Errors See Section 3.4.3.3.3 EMSD-SA Invoked Operations
This section defines the operations invoked by the EMSD-SA: a. deliver; b. submissionControl; c. submissionVerify. The deliver operation uses 3-Way handshake service of ESROS. This operation always uses the duplication detection functional unit. The submissionControl and submissionVerify operations use 2-Way handshake service of ESROS without duplication detection.3.3.1 deliver
The deliver ES-OPERATIONS enables the EMSD-SA to deliver a message to an EMSD-UA. deliver ES-OPERATION ARGUMENT DeliverArgument RESULT NULL ERRORS { deliveryControlViolated, securityError, resourceError, protocolViolation, messageError } ::= 35;
The EMSD-UA MUST not refuse performing the deliver ES-OPERATION
unless the delivery would violate the deliveryControl restrictions
then in force.
Arguments
This operation's arguments are:
DeliverArgument ::= SEQUENCE
{
-- Identifier of this message. This is the same identifier that
-- was provided to the originator in the Submission Result.
-- See comment regarding assignment of message identifiers,
-- at the definition of EMSDMessageId.
message-id EMSDMessageId,
-- Time the message was delivered to the recipient by EMSD-SA
message-delivery-time DateTime,
-- Time EMSD-SA originally took responsibility for processing
-- of this message. This field shall be omitted if the message-id
-- contains an EMSDLocalMessageId, because that field contains
-- the submission time within it.
message-submission-time [0] IMPLICIT DateTime OPTIONAL,
-- Security features
security [1] IMPLICIT SecurityElement OPTIONAL,
-- SegContentTypementation features for efficient transport
segment-info SegmentInfo OPTIONAL,
-- The type of the content
content-type ContentType,
--
-- THE CONTENT --
--
-- The submitted (and now being delivered) content
content ANY DEFINED BY content-type
};
message-id This argument contains an EMSD-SA-identifier that distinguishes the message from all other messages. When within the EMSD, it MUST be generated by the EMSD-SA, and MUST have the same value as the message-submission-identifier supplied to the originator of the message when the message was submitted. Message-delivery-time This argument contains the Time at which delivery occurs and at which the EMSD-SA is relinquishing responsibility for the message. It shall be generated by the EMSD-SA. Results This operation returns an empty result as indication of success. Errors See Section 3.4.3.3.3.2 submissionControl
submissionControl ES-OPERATION ARGUMENT SubmissionControlArgument RESULT SubmissionControlResult ERRORS { securityError, resourceError, protocolViolation } ::= 4; The submissionControl ES-OPERATIONS enables the EMSD-SA to temporarily limit the operations that the EMSD-UA may invoke, and the messages that the EMSD-UA may submit to the EMSD-SA via the submit ES-OPERATIONS. The duplicate operation detection is not required for this operation. The EMSD-UA should hold until a later time, rather than abandon, ES- OPERATIONS and messages that are presently suspended.
The successful completion of the ES-OPERATIONS signifies that the
specified controls are now in force. These controls supersede any
previously in force, and remain in effect until the association is
released or the EMSD-SA re-invokes the submissionControl ES-
OPERATIONS.
The ES-OPERATIONS returns an indication of any ES-OPERATIONS that the
EMSD-UA would invoke were it not for the prevailing controls.
Arguments
This operation's arguments are:
SubmissionControlArgument ::= SEQUENCE
{
-- Request an addition of or removal of a set of restrictions
restrict [0] IMPLICIT Restrict DEFAULT update,
-- Which operations are to be placed in the restriction set
permissible-operations [1] IMPLICIT Operations OPTIONAL,
-- What maximum content length should be allowed
permissible-max-content-length
[2] IMPLICIT INTEGER
(0..ub-content-length) OPTIONAL,
-- Security features
security [3] IMPLICIT SecurityElement
OPTIONAL
};
Restrict
This argument indicates whether the controls on ES-OPERATIONS are to
be updated or removed. It may be generated by the EMSD-SA.
This argument may have one of the following values:
o update: The other arguments update the prevailing controls;
o remove: All temporary controls are to be removed
In the absence of this argument, the default update shall be assumed.
Permissible-operations
This argument indicates the ES-OPERATIONS that the EMSD-UA may invoke
on the EMSD-SA. It may be generated by the EMSD-SA.
This argument may have the value allowed or prohibited for each of
the following:
o submit: The EMSD-UA may/may not invoke the submit ES-
OPERATIONS; and
o Other ES-OPERATIONS are not subject to controls, and may be
invoked at any time.
In the absence of this argument, the ES-OPERATIONS that the EMSD-UA
may invoke on the EMSD-SA are unchanged.
Permissible-max-content-length
This argument contains the content-length, in octets, of the
longest-content message that the EMSD-UA shall submit to the EMSD-SA
via the submit ES-OPERATIONS. It may be generated by the EMSD-SA.
In the absence of this argument, the permissible-maximum-content-
length of a message that the EMSD-UA may submit to the EMSD-SA is
unchanged.
Security
See Section 3.4.1, "SecurityElements".
Results
SubmissionControlResult ::= SEQUENCE
{
-- Operation types queued at the EMSD-SA due to existing
-- restrictions.
waiting-operations [0] IMPLICIT Operations DEFAULT { }
};
Waiting-operations
This result indicates the ES-OPERATIONS being held by the EMSD-UA,
and that the EMSD-UA would invoke if it were not for the prevailing
controls. It may be generated by the EMSD-UA.
This result may have the value holding or not-holding for each of the
following:
o submit: The EMSD-UA is/is not holding messages, and would
invoke the submit ES-OPERATIONS if it were not for the
prevailing controls.
In the absence of this result, it may be assumed that the EMSD-UA is
not holding any messages for submission due to the prevailing
controls.
Errors
See Section 3.4.3.
3.3.3 submissionVerify
The submissionVerify ES-OPERATIONS enables the EMSD-SA to verify if
the EMSD-UA has received the result of its submission.
submissionVerify ES-OPERATION
ARGUMENT SubmissionVerifyArgument
RESULT SubmissionVerifyResult
ERRORS
{
submissionVerifyError,
resourceError,
protocolViolation
} ::= 6;
The duplicate operation detection is not required for this operation.
Arguments
This operation's arguments are:
SubmissionVerifyArgument ::= SEQUENCE
-- Identifier of this message. This is the same identifier that
-- was provided to the originator in the Submission Result.
-- See comment regarding assignment of message identifiers,
-- at the definition of EMSDMessageId.
{
message-id EMSDMessageId
};
Message-id
This argument contains an EMSD-SA-identifier that distinguishes the
message from all other messages. It shall be generated by the EMSD-
SA, and shall have the same value as the message-submission-
identifier supplied to the originator of the message when the message
was submitted.
Results
SubmissionVerifyResult ::= SEQUENCE
{
status SubmissionStatus
};
SubmissionStatus::= ENUMERATED
{
send-message (1),
drop-message (2)
};
Send-message
This result indicates that EMSD-SA is supposed to send the message
out.
Drop-message
This result indicates that EMSD-SA is supposed to drop the message.
Errors
See Section 3.4.3.
3.4 EMSD Common Information Objects
3.4.1 SecurityElements
SecurityElement ::= SEQUENCE { credentials Credentials, contentIntegrityCheck ContentIntegrityCheck OPTIONAL }; Credentials ::= CHOICE { simple [0] IMPLICIT SimpleCredentials -- Strong Credentials are for future study -- strong [1] IMPLICIT StrongCredentials -- externalProcedure [2] EXTERNAL }; SimpleCredentials ::= SEQUENCE { eMSDAddress EMSDAddress OPTIONAL, password [0] IMPLICIT OCTET STRING SIZE (0..ub-password-length)) OPTIONAL }; -- StrongCredentials ::= NULL -- for now. -- ContentIntegrityCheck is a 16-bit checksum of content ContentIntegrityCheck ::= INTEGER (0..65535);3.4.2 Message Segmentation and Reassembly
Small messages can benefit from the efficiencies of connectionless feature of ESROS (See Efficient Short Remote Operations, RFC-2188 [1]). Very large messages are transferred using protocols (e.g., SMTP) that rely on Connection Oriented Transport Service (e.g., TCP). When a message is too large to fit in a single connectionless PDU but is not large enough to justify the overhead of connection establishment, it may be more efficient for the message to be segmented and reassembled while the connectionless service of ESROS is used. If the underlying Remote Operation Service is capable of efficient segmentation/reassembly over connectionless (CL) services,
then use of the segmenting/reassembly mechanism introduced in this
section is not necessary. This feature is accommodated in this layer
by:
SegmentInfo ::= CHOICE
{
first [APPLICATION 2] IMPLICIT FirstSegment,
other [APPLICATION 3] IMPLICIT OtherSegment
};
FirstSegment ::= SEQUENCE
{
sequence-id INTEGER,
number-of-segments INTEGER
-- number-of-segments must not exceed ub-total-number-of-segments
};
OtherSegment ::= SEQUENCE
{
sequence-id INTEGER,
segment-number INTEGER
};
Segmentation and reassembly only applies to Message-submission and
Message-delivery.
The sender of the message is responsible for segmenting the message
content into segments that fit in CL PDUs. The segmented content is
sent in a sequence of message-segments each carrying a segment of the
content. sequence-Id is a unique identifier that is present in all
message-segments. In addition to sequence identifier, the first
message-segment specifies the total number of segments (number-of-
segments). Other message-segments have a segment sequence number
(segment-number). The receiver is responsible for sequencing (based
on segment-number) and reassembling the entire message.
Segmenting over the Connectionless ESRO Service
The sender of the message maps the original message into an ordered
sequence of message-segments. This sequence shall not be interrupted
by other messages over the same ESROS association.
All message-segments in the sequence shall be assigned a sequence
identifier by sender. The sequence identifier shall be incremented
by one by the sender after transmission of a complete message
sequence.
The first message-segment specifies the total number of segments.
All message-segments in the sequence except the first one shall be
sequentially numbered, starting at 1 (first message-segment has
implicit segment number of 0).
Each message-segment is transmitted by issuing a Message-submission
or Message-delivery ES-OPERATIONS. All segments of a segmented
message are identified by the same sequence-id. For a given message,
the receiver should not impose any restriction on the order of
arrival of message-segments.
There is no requirement that any message-segment content be of
maximum length allowed by ESROS for connectionless transmission;
however, no more than ub-total-number-of-segments segments can be
derived from a single message.
The receiver reassembles a sequence of message-segments into a single
message. A message shall not be further processed unless all
segments of the message are received. Failure to receive the message
shall be determined by the following events:
o Expiration of Reassembly Timer (see Section 3.4.3).
o Receipt of a message-segment with different sequence identifier.
In the event of the above mentioned failures, the receiver shall
discard a partially assembled sequence.
In Reassembly process, all arguments other than content are ignored
in all segments except the first one. The content parts of all
segments are concatenated to compose the original message content.
When sender receives FAILURE.indication (as opposed to a
resourceError) for a message-segment, the whole message shall be
retransmitted.
In the case of submission and delivery operations, the verify
function is used as described below:
Receiver ignores FAILURE.indications received for message-segments,
and just collects the message-segments to complete the message.
However, it keeps a failure status for a segmented message which says
if any segment of the message has received FAILURE.indication. When
receiver succeeds to assemble the whole segmented message, then if
the status of the message shows there has been a FAILURE.indication
for any of the message-segments, it verifies the message through
verify operation. It's not enough to invoke verify operation just
based on the last message-segment because the sender might send a
segment without waiting for the result of the previous segment. In such cases, there might be any combination of success and failure for message-segments on the sender side. Receiver uses the error code ResourceError (see Section 3.4.3) to ask for retransmission of a single segment and uses the error code MessageError (see Section 3.4.3) to ask for retransmission of all segments (the whole message). Reassembly Timer The Reassembly Timer is a local timer maintained by the receiver of message-segments that assists in performing the reassembly function. This timer determines how long a receiver waits for all segments of a message-segment sequence to be received. The timer protects the receiver from the loss of a series of segments and possible sequence identifier wrap-around. The Reassembly Timer shall be started on receipt of a message-segment with different sequence identifier than that previously received. The timer shall be stopped on receipt of all segments composing the sequence. The value of Reassembly Timer is defined based on the network characteristics and the number of segments. This requires that the transmission of all segments of a single message must be completed within this time limit.3.4.3 Common Errors
protocolVersionNotRecognized ERROR PARAMETER NULL ::= 1; submissionControlViolated ERROR PARAMETER NULL ::= 2; messageIdentifierInvalid ERROR PARAMETER NULL ::= 3; securityError ERROR PARAMETER security-problem SecurityProblem ::= 4; deliveryControlViolated ERROR PARAMETER NULL ::= 5; resourceError ERROR PARAMETER NULL ::= 6; protocolViolation ERROR PARAMETER NULL ::= 7; messageError ERROR PARAMETER NULL ::= 8; SecurityProblem ::= INTEGER (0..127);
protocolVersionNotRecognized The major and minor protocol versions presented do not match those recognized as being valid. submissionControlViolated The Submission control violated error reports the violation by the MTS-user of a control on submission services imposed by the MTS via the Submission control service. The Submission control violated abstract-error has no parameters. messageIdentifierInvalid The Message Identifier Invalid error reports that the Message Identifier presented to the MTS is not considered valid. securityError The Security error reports that the requested operation could not be provided by the MTS or MTS-user because it would violate the security policy in force. deliveryControlViolated The Delivery control violated error reports the violation by the MTS of a control on delivery operations imposed by the MTS-user via the Delivery-control operation. resourceError The messaging agent cannot currently support this operation. In the case of segmentation and reassembly, resourceError is by the receiver used to request that the sender retransmit of a single segment. protocolViolation Indicates that one or more mandatory argument(s) were missing.
messageError For a multi-segment message, this error indicates that the messaging agent has not received the message completely and that the message must be retransmitted. SecurityProblem To ensure the security-policy is not violated during delivery, the message-security-label is checked against the security-context. If delivery is barred by the security-policy then, subject to the security policy, a report instruction for this is generated.3.4.4 ContentType
ContentType ::= INTEGER { -- Content type 0 is reserved and shall never be transmitted. reserved (0), -- Content types between 1 and 31 (inclusive) are for -- internal-use only probe (1), -- reserved delivery-report (2), -- reserved -- Content types between 32 and 63 (inclusive) are for -- message types defined within this specifications. emsd-interpersonal-messaging-1995 (32), voice-messaging (33) -- reserved -- Content types beyond and including 64 are for -- bilaterally-agreed use between peers. } (0..127);3.4.5 EMSDMessageId
If this message was originated as an RFC-822 message, then this EMSDMessageId shall be the "Message-Id:" field from that message. If this message was originated within the EMSD domain, then this identifier shall be unique for the EMSD-SA generating this id. EMSDMessageId ::= CHOICE { EMSDLocalMessageId [APPLICATION 4] IMPLICIT EMSDLocalMessageId, rfc822MessageId [APPLICATION 5] IMPLICIT AsciiPrintableString
(SIZE (0..ub-message-id-length))
};
EMSDLocalMessageId ::= SEQUENCE
{
submissionTime DateTime,
messageNumber INTEGER (0..ub-local-message-nu)
};
3.4.6 EMSDORAddress
EMSDORAddress ::= CHOICE
{
-- This is the local-format address
emsd-local-address-format EMSDAddress,
-- This is a globally-unique RFC-822 Address
rfc822DomainAddress AsciiPrintableString
};
In the global sense Originators and Recipients are represented by
EMSDORAddress. The rfc822Domain may be used to address any
recipient.
3.4.7 EMSDAddress
EMSDAddress ::= SEQUENCE
{
emsd-address OCTET STRING (SIZE
(1..ub-emsd-address-length)),
-- emsd-address is a decimal integer in BCD
(Binary Encoded Decimal) format.
-- If it had an odd number of digits, it is
-- padded with 0 on the left.
emsd-name [0] IMPLICIT OCTET STRING
(SIZE (0..ub-emsd-name-length))
OPTIONAL
};
Originator and Recipients in the scope of EMSD network are identified
by a digit based addressing scheme. EMSDAddress can only be used
where the scope of addressing has clearly been limited to the EMSD
network.
3.4.8 DateTime
DateTime ::= INTEGER;
DateTime is a Julian date, expressed as the number of seconds since 00:00:00 UTC, January 1, 1970.3.4.9 AsciiPrintableString
Iso8859String ::= GeneralString; AsciiPrintableString ::= [APPLICATION 0] IMPLICIT Iso8859String (FROM (" "|"!"|"#"|"$"|"%"|"&"|"'"|"("|")"|"*"|"+"|","|"-"|"."|"/"| "0"|"1"|"2"|"3"|"4"|"5"|"6"|"7"|"8"|"9"|":"|";"|"<"|"="|">"| "?"|"@"|"A"|"B"|"C"|"D"|"E"|"F"|"G"|"H"|"I"|"J"|"K"|"L"|"M"| "N"|"O"|"P"|"Q"|"R"|"S"|"T"|"U"|"V"|"W"|"X"|"Y"|"Z"|"["|"]"| "^"|"_"|"`"|"a"|"b"|"c"|"d"|"e"|"f"|"g"|"h"|"i"|"j"|"k"|"l"| "m"|"n"|"o"|"p"|"q"|"r"|"s"|"t"|"u"|"v"|"w"|"x"|"y"|"z"|"{"| "|"|"}"|"~"|"\"|""""));3.4.10 ProtocolVersionNumber
ProtocolVersionNumber ::= [APPLICATION 1] SEQUENCE { version-major INTEGER, +------------------+-------+----+---------+----+---------+-----+-----+ |Operation |Invoker|Sap |Performer|Sap |Duplicate|OpId |ESROS| | | |Sel | |Sel |Detect | |Use | |__________________|_______|____|_________|____|_________|_____|_____| |submit |UA |4 |MTS |5 |Yes |33 |3-Way| |__________________|_______|____|_________|____|_________|_____|_____| |deliver |MTS |2 |UA |3 |Yes |35 |3-Way| |__________________|_______|____|_________|____|_________|_____|_____| |deliveryControl |UA |8 |MTS |9 |No |2 |2-Way| |__________________|_______|____|_________|____|_________|_____|_____| |submissionControl |MTS |6 |UA |7 |No |4 |2-Way| |__________________|_______|____|_________|____|_________|_____|_____| |submissionVerify |MTS |6 |UA |7 |No |6 |2-Way| |__________________|_______|____|_________|____|_________|_____|_____| |deliveryVerify |UA |8 |MTS |9 |No |5 |2-Way| |__________________|_______|____|_________|____|_________|_____|_____| |getConfiguration |UA |8 |MTS |9 |No |7 |2-Way| |__________________|_______|____|_________|____|_________|_____|_____| |setConfiguration |MTS |6 |UA |7 |No |8 |2-Way| +------------------+-------+----+---------+----+---------+-----+-----+ Table 1: EMSD-P Operations Summary
version-minor [0] IMPLICIT INTEGER DEFAULT 0
}
3.5 Submission and Delivery Procedures
Table 1 provides a comprehensive summary of EMSD-P operations, the
SAP selectors used and the operation IDs used.
Submission
The semantics of a submission operation is Exactly Once. Exactly
Once means that every operation is carried out exactly one time, no
more and no less. This semantic can not be fully implemented
because, if after invoking the operation, an invoker has a Success
(e.g. result) indication and the performer has a FAILURE.indication,
and the network goes down, the result of the operation will be Zero
(and not Exactly Once).
No more than one is controlled and guaranteed by the performer by
using the Duplicate Operation Detection Support Functions (see the
chapter entitled Duplicate Operation Detection Support).
Not zero but one is realized by performer by using the
SubmissionVerify operation. When the performer receives
FAILURE.indication, it's responsibility is to resolve the case by
using SubmissionVerify resulting in Not zero but one.
Submission procedure is as follows:
o Submit operation with 3-Way handshake and Duplicate Operation
Detection Support Function is invoked.
o If performer at EMSD-SA receives FAILURE.indication, it invokes
SubmissionVerify.
o Message is sent out by EMSD-SA only if result operation is
confirmed or the operation is verified (in the case of
FAILURE.indication).
The semantic of SubmissionVerify operation is At Least Once. This
type of semantics corresponds to the case that invoker keeps trying
over and over until it gets a proper reply. This operation can be
performed more than once without any harm.
Implications:
o MTS sends out the message if and only if it's sure that UA knows
about it.
Delivery
The semantics of Deliver operation is Exactly Once. Exactly Once
means that every operation is carried out exactly one time, no more
and no less. This semantic can not be fully implemented and if after
invoking the operation, invoker has Success indication and performer
has FAILURE.indication, and the network goes down, the result of the
operation will be Zero (and not Exactly Once).
No more than one is controlled and guaranteed by performer and by
using the Duplicate Operation Detection Support Functions.
Not zero but one is realized by performer by using the DeliveryVerify
operation. When performer receives FAILURE.indication, it's
responsible to resolve the case by using DeliveryVerify resulting in
Not zero but one.
Delivery procedure is as follows:
o Deliver operation with 3-Way handshake is invoked.
o If performer at User Agent (device) receives FAILURE.indication,
it invokes DeliveryVerify.
The semantic of DeliveryVerify operation is At Least Once. This type
of semantics corresponds to the case that invoker keeps trying over
and over until it gets a proper reply. This operation can be
performed more than once without any harm.
Implications:
o A non-delivery report is sent by MTS only if the message is not
delivered.
o The UA is responsible for notifying the MTS (through an explicit
deliveryVerify) to make sure that a delivery report is sent out.
(next page on part 3)