RFC2652 - MIME Object Definitions for the Common Indexing Protocol (CIP)

领测软件测试网

　　 
　　Network Working Group J. Allen
Request for Comments: 2652 WebTV Networks, Inc.
Category: Standards Track M. Mealling
Network Solutions, Inc.
August 1999

MIME Object Definitions for the Common Indexing Protocol (CIP)

Status of this Memo

This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1999). All Rights Reserved.

Abstract

The Common Indexing Protocol (CIP) is used to pass indexing
information from server to server in order to facilitate query
routing. The protocol is comprised of several MIME objects being
passed from server to server. This document describes the definitions
of those objects as well as the methods and requirements needed to
define a new index type.

1. Introduction

The Common Indexing Protocol (CIP) is used to pass indexes between
servers that combine multiple indexes and/or route queries based on
those indexes. The overall framework for the protocol is specified in
the CIP Framework document [FRAMEWORK]. This document should be read
within the context of that document as there are fundamental concepts
contained in the framework that are not fully explained here.

Since there are several different ways to index a given database
there will be multiple types of indexes to pass. These indexes may
have different transport requirements, different ways of specifying
parameters, and different referral rules. These different
requirements are handled by encapsulating the indexes within MIME
wrappers in order to have a standardized way to specify those
different parameters.

Appendix A contains the actual MIME [RFC2046] registration templates
sent to the IANA for registration [RFC2048].

This document uses language like SHOULD and SHALL that have special
meaning as specified in "Key words for use in RFCs to Indicate
Requirement Levels" [RFC2119].

2.0 CIP Transactions

Messages passed by CIP implementations over reliable transport
mechanisms fall into three categories: requests, responses and
results. All requests result in either a response or a result. A
result sent in response to a request must be interpreted as a
successful operation.

Requests, responses and results are formatted as MIME [RFC2046]
messages. The specific MIME types involved are defined below.

As with all MIME objects, CIP messages may be wrapped in a security
multipart package to provide authentication and privacy. The security
policy with respect to all messages is implementation defined, when
not explicitly discussed below. CIP implementors are strongly urged
to allow server administrators maximum configurability to secure
their servers against maliciously sent anonymous CIP messages. In
general, operations which can permanently change the server's state
in a harmful way should only take place upon receipt of a properly
signed message from a trusted CIP peer or administrator. Implementors
should provide appropriate auditing capabilities so that both
successful and failed requests can be tracked by the server
administrator.

Since these MIME objects can and will be sent over several different
protocols, body termination is specified by the transfer protocol.
New protocols are encouraged to use SMTP [RFC821] style body
termination.

Finally, since MIME objects can specify their own encoding, the
line-breaks contained within each body are defined by the encoding.
Thus, instead of specifying them as carriage-return and/or linefeed,
the identifier <linebreak> is used. Linebreaks in the headers and
separating the body from the headers follow existing standards.

2.1 Common syntactic definitions

There are certain syntactic elements common to all of the CIP
transactions. These include type, DSI and the Base-URI.

2.1.1 The "application/index" MIME type tree

Due to requirements in RFC2048 concerning objects that have the same
type but different syntaxes, CIP objects will use the
application/index tree but include "facets" [RFC2048] which extend it
as other types have done with respect to global elements and vendor
specific enhancements. Thus the tree is divided up into the following
branches:

application/index.cmd._command_
application/index.response
application/index.obj._type_
application/index.vnd._xxx_

_command_ is a command as specified here. It contains commands and
their arguments.

_type_ identifies what type of CIP index object is contained
within the body. It is unique among all other reserved types.
Reserved types are those previously documented by other CIP index
object specifications, according to standard IETF processes.

_xxx_ is an identifier specified by a vendor for use by that
vendor in operations specifically to do with indexes.

All of the above identifiers follow the rules in RFC2048 for valid
MIME types. In addition commands, responses and types are limited by
this document to consist of from 1 to 20 characters from the set [a-
zA-Z0-9-]; that is, all upper and lower case letters, all digits, and
the ASCII minus character (decimal 45). Though type names may be
specified case sensitively, they must be compared and otherwise
processed case insensitively.

Appendix A contains the registration template for the
application/index tree.

2.1.2 DSI

A dataset identifier is an identifier chosen from any part of the
ISO/CCITT OID space. The DSI uniquely identifies a given dataset
among all datasets indexed by CIP.

As currently defined, OID's are an unbounded sequence of unbounded
integers. While this creates an infinite numbering space, it presents
problems for implementors dealing with machines with finite
resources. To ease implementation, this document specifies an ASCII
encoding of the OID, and specifies limits which make implementation
easier.

For the purposes of interchange in CIP messages, an OID must conform
to the following rules:

dsi = integer *( "." integer)
integer = all-digits / (one-to-nine *all-digits)
one-to-nine = "1" / "2" / "3" / "4" / "5" / "6" / "7" /
"8" / "9"
all-digits = "0" / one-to-nine

Under no circumstances shall the total length of the resulting string
exceed 255 characters. OID's which cannot, due to their length,
conform to these rules must not be used as CIP dataset identifiers.

An implementation must not attempt to parse the individual integers
unless it is prepared to handle arbitrary-length integers. Treating
the DSI as anything other than an opaque string of US-ASCII
characters is not recommended.

Two CIP DSI's are considered to match if both conform to the above
rules and every number matches.

2.1.3. Base-URI

CIP index objects carry base-URI's to facilitate referral generation
based on the index object. The base-URI parameter carries a
whitespace-delimited list of URL's. URL's are defined in RFC-1738.
The exact rules are as follows:

base-uri = genericurl *( 1*whitespace genericurl )
whitespace = "<space>" (decimal 32) /
"<tab>" (decimal 9) /
"<cr>" (decimal 13) /
"<lf>" (decimal 10)
genericurl = { as specified in RFC-1738, section 5 }

2.2 Response format

All requests must be followed by a response code, except in the cases
where a return path is unavailable.

The definition for this MIME type is:

MIME type name: application
MIME subtype name: index.response
Required parameters: code
Optional parameters: charset
Security considerations: (See Section 4)

The code parameter contains a 3 digit return code that denotes the
status of the last command.

The format of the body is such that the first line is interpreted as
the comment corresponding to the code. As with most response codes
this comment is intended for human consumption and may not exist and
must not be depended on by the protocol. Subsequent lines in the body
are reserved for each response to define. In the case where the
comment is not given the first must be an empty line.

body = comment linebreak payload
comment = { any text }
linebreak = (decimal 13) (decimal 10)
payload = { any text }

The charset parameter has its normal MIME meaning. Below are several
examples:

[begin MIME]
Content-type: application/index.response; code=220

CIP Server v1.0 ready!<linebreak>
[end MIME]

[begin MIME]
Content-type: application/index.response; code=500

MIME formatting problem<linebreak>
[end MIME]

[begin MIME]
Content-type: application/index.response; code=520

<linebreak>
[end MIME]

While the responses described in this document do not utilize the
rest of the lines in the body of a response implementors should take
care to not disallow it in the future. A good example would be a
message specifying that a poll request did not contain required
attributes. This message might look like this:

[begin MIME]
Content-type: application/index.response; code=502

Request is missing required CIP attributes
Missing-Attribute: attribute1
Missing-Attribute: attribute2
Missing-Attribute: attribute3
[end MIME]

The meaning of the various digits in the response codes is discussed
in RFC-821, Appendix E.

See Appendix B for a list of the valid response codes.

2.3 Command format

A CIP command either initiates an index transfer, interrogates the
state of the receiver-CIP (or the server's participation in the
mesh), or changes the state of the server (or the server's place in
the mesh).

CIP commands are sent as a MIME message of type
"application/index.cmd._command_". The definition for this MIME type
tree follows:

MIME type name: application
MIME subtype name: index.cmd._command_
Optional parameters: type, dsi
Security considerations: (See Section 4)

The format of the body is defined by each command. A general
attribute/value pair orientation is preserved throughout the
following specified commands. Those developing future command should
attempt to maintain that orientation but are not required to do so.

In the following sections, the server's response for each possible
value for "command" is defined. Note that the parameters listed as
optional above are only optional with respect to the generic MIME
form. The optional parameters are only optional with respect to MIME
parsing. If one or more of the parameters needed to fulfill a command
is missing, a response code of 502 is returned.

Extra optional parameters which are unrecognized must be silently
ignored.

2.3.1 No-operation

Command Name: application/index.cmd.noop
Required parameters: (none)

A CIP command with the "command" parameter set to "noop" must be
acknowledged with response type code 200 (command OK, no response
forthcoming).

This command must not require a signed MIME object. Implementations
should accept commands which have been validly signed.

Example:

[begin MIME]
Content-type: application/index.cmd.noop

[end MIME]

Note the lack of a body but how the <linebreak> pair is still
preserved after the Content-type header.

2.3.2 Poll

Request Name: application/index.cmd.poll
Required parameters: type, dsi

The "poll" command is used by a poller to request the transfer of an
index object. It requires the following parameters:

type: The index object type requested
dsi: The dataset which the index should cover

If there are no index objects available for a given DSI, or the
receiver-CIP does not support a given index object type, the
receiver-CIP must respond with response code 200, (successful, no
response forthcoming). Otherwise, the response code must be 201
(successful, response is forthcoming).

The security policy for polling commands is wholly implementation
defined. Implementations may be configured to accept or reject
anonymous poll commands.

Example:

[begin MIME]
Content-type: application/index.cmd.poll; type="simple";
dsi= "1.3.5.7.9"

Template: contact name address phone<linebreak>
Start-time: Fri May 30 14:25:30 EDT 1997<linebreak>
End-time: Sat May 31 14:25:30 EDT 1997<linebreak>
[end MIME]

2.3.3 DataChanged

Request Name: application/index.cmd.datachanged
Required parameters: type, dsi

The "datachanged" command is used by a pollee to notify a poller that
the data within an index has changed. It requires the following
parameters:

type: The index object type requested
dsi: The dataset which the index should cover

If there are no index objects available for a given DSI, or the
receiver-CIP does not support a given index object type, the
receiver-CIP must respond with response code 200, (successful, no
response forthcoming). Otherwise, the response code must be 201
(successful, response is forthcoming).

The body of a DataChanged command is formatted as a simple set of
attribute value pairs following the rules of RFC822. The actual
attributes and values allowed are defined by the index type
specification.

The security policy for DataChanged commands is wholly implementation
defined. Implementations may be configured to accept or reject
anonymous DataChanged commands.

Example:

[begin MIME]
Content-type: application/index.cmd.datachanged;
type="simple"; dsi= "1.3.5.7.9"<linebreak>

Time-of-latest-change: Fri May 30 14:25:30 EDT 1997<linebreak>
Time-of-message-generation: Fri May 30 14:25:30 EDT 1997<linebreak>
Host-Name: cip.rwhois.net<linebreak>
Host-Port: 4322<linebreak>
Protocol: RWhois2.0<linebreak>
[end MIME]

2.3.4 Additional Requests

The requests specified above are those required to implement a simple
mesh. It is expected that other requests will be developed to handle
issues of mesh-management and statistics gathering requests. At this
point this is an area of additional work. Specifically more work is
needed in the area of mesh management as meshes will tend to be
organized around the characteristics of their index type.

2.4. Index Object format

In reply to the "poll" command, a server may choose to send one or
more index objects. Regardless of the number of index objects
returned, the response must take the form of a MIME multipart/mixed
message. Each part must itself be a MIME object of type
"application/index.obj._type_". The definition for this type follows:

MIME type name: application
MIME subtype name: index.obj._type_
Required parameters: dsi, base-uri
Optional parameters: none
Security considerations: (See Section 4)

As previously described, each index object is of a particular
type. This type is specified in the MIME subtype name since some
types may have a different syntax.

The required parameters are to be used as follows:

DSI: The DSI is a string which globally uniquely identifies
the dataset from which the index was created.

base-URI: One or more URI's will form the base of any referrals
created based upon this index object.

3. Index Type Definition Requirements

Because of the need for application domain specific indices, CIP
index objects are abstract; they must be defined by a separate
specification. The basic protocols for moving index objects are
widely applicable, but the specific design of the index, and the
structure of the mesh of servers which pass a particular type of
index is dependent on the application domain. While companion
documents will describe index objects, there is a set of base
requirements and questions those documents must address. This is to
ensure that the base assumptions that the CIP protocol makes about
its indexes are actually expressible within the index.

Since each type is a MIME type all its own, registration of new types
follows the standard registration policies specified in RFC2048.

3.1 Type specific requests

Any index type definition must address the type specific bodies of
the Poll and DataChanged requests. All parameters included in the
body must be specified.

3.2 The index.obj parameters

3.2.1 Type

See the above definitions for allowed values for type.

A new name must be assigned when any changes to the document
describing the index object type are not completely backwards
compatible.

3.2.2 DSI

Another attribute is the "DSI", or Dataset Identifier, which uniquely
identifies the dataset from which the index was created. The index
specification should define the policies for how the DSI is
generated. This includes the concept of what a data-set means for the
given index.

3.2.3. Base-URI

An attribute of the index object which is crucial for generating
referrals is the "Base-URI". The URI (or URI's) contained in this
attribute form the basis of any referrals generated based on this
index block. The URI is also used as input during the index
aggregation process to constrain the possible types of aggregation.
This use of the Base-URI is used to deal with meshes that support
multiple protocols.

Thus, an index specification should define how the Base-URI applies
to the underlying index and how it is changed during the aggregation
process.

3.3 Aggregation

All index object specifications must address the issue of
aggregation. This is the method by which an index server takes two
or more indexes and combines them into one index to be passed on. It
is not required that a given index-type aggregate. If it does not it
must explicitly address the reasons why and what affect that has on
scalability.

If a given index does aggregate, the algorithm for that aggregation
must be given. It must also address how that algorithm affects mesh
organization and scalability.

Index object document authors should remember that any kind of
aggregation should be performed without compromising the ability to
correctly route queries while avoiding excessive numbers of missed
results. The acceptable likelihood of false negatives must be
established on a per-application-domain basis, and is controlled by
the granularity of the index and the aggregation rules defined for it
by the particular specification.

Nothing in these documents specifically disallows aggregation rules
that deal with different index object types. This type of
heterogeneous mesh is difficult to formulate at best and thus is not
covered by these documents. If document authors wish to attempt such
a mesh they should be aware that it is considered an ill understood
concept that contains many pitfalls for the mesh builder.

3.4 Referral Generation Semantics

Since the method by which a client navigates the mesh is by
referrals, the document must address how a given access protocol
generates a referral from the index. Authors should pay particular
attention to the case where an index is accessed by different
protocols and the interaction between them. For example, an index
that supports referrals being generated for both RWhois and LDAP must
understand that one uses a Distinguished Name while the other
doesn't. The impacts of these differences on the referral should be
clear.

3.5 Matching Semantics

In order to generate a referral the decision of whether or not to do
so must be handled by the access protocol. The semantics surrounding
this decision have a large impact on the efficiency of searches as
well as the requirements on aggregation. Thus, index specification
authors must be very clear about how a match is determined.

3.6 Security Considerations

As is customary with Internet protocol documentation, a brief review
of security implications of the proposed object must be included.
This section may need to do little more than echo the considerations
expressed in this document's Security Considerations section.

3.7 Optional Coverage

Because indexing algorithms, stop-lists, and data reduction
technologies are considered by some index object designers to be
proprietary, it is not necessary to discuss the process used to
derive indexing information from a body of source material. When
proprietary indexing technologies are used in a public mesh, all CIP
servers in the mesh should be able to parse the index object (and
perform aggregation operations, if necessary), though not all of them
need to be able to create these proprietary indices from source data.

Thus, index object designers may choose to remain silent on the
algorithms used for the generation of indices, as long as they
adequately document how to participate in a mesh of servers passing
these proprietary indices.

Designers should also seriously consider including useful examples of
source data, the generated index, and the expected results from
example matches. When the aggregation algorithm is complex, it is
recommended that a table showing two indices and the resultant
aggregate index be included.

4. Security Considerations

Security considerations come into play in at least the following two
scenarios. Indexing information can leak undesirable amounts of
proprietary information, unless carefully controlled. At a more
fundamental level, the CIP protocol itself requires external security
services to operate in a safe manner. Both topics are covered below.

4.1 Secure Indexing

CIP is designed to index all kinds of data. Some of this data might
be considered valuable, proprietary, or even highly sensitive by the
data maintainer. Take, for example, a human resources database.
Certain bits of data, in moderation, can be very helpful for a
company to make public. However, the database in its entirety is a
very valuable asset, which the company must protect. Much experience
has been gained in the directory service community over the years as
to how best to walk this fine line between completely revealing the
database and making useful pieces of it available.

Another example where security becomes a problem is for a data
publisher who would like to participate in a CIP mesh. The data that
publisher creates and manages is the prime asset of the company.
There is a financial incentive to participate in a CIP mesh, since
exporting indices of the data will make it more likely that people
will search your database. (Making profit off of the search activity
is left as an exercise to the entrepreneur.) Once again, the index
must be designed carefully to protect the database while providing a
useful synopsis of the data.

One of the basic premises of CIP is that data providers will be
willing to provide indices of their data to peer indexing servers.
Unless they are carefully constructed, these indices could constitute
a threat to the security of the database. Thus, security of the data
must be a prime consideration when developing a new index object
type. The risk of reverse engineering a database based only on the
index exported from it must be kept to a level consistent with the
value of the data and the need for fine-grained indexing.

Since CIP is encoded as MIME objects, MIME security solutions should
be used whenever possible. Specifically when dealing with security
between index servers.

4.2 Protocol Security

CIP protocol exchanges, taking the form of MIME messages, can be
secured using any technology available for securing MIME objects. In
particular, use of RFC-1847's Security Multiparts are recommended. A
solid application of RFC-1847 using widely available encryption
software is PGP/MIME, RFC-2016. Implementors are encouraged to
support PGP/MIME, as it is the first viable application of the MIME
Security Multiparts architecture. As other technologies become
available, they may be incorporated into the CIP mesh.

If an incoming request does not have a valid signature, it must be
considered anonymous for the purposes of access control. Servers may
choose to allow certain requests from anonymous peers, especially
when the request cannot cause permanent damage to the local server.
In particular, answering anonymous poll requests encourages index
builders to poll a server, making the server's resources better
known.

The explicit security policy with respect to incoming requests is
outside the scope of this specification. Implementors are free to
accept or reject any request based on the security attributes of the
incoming message. When a request is rejected due to authentication
reasons, a response code from the 530 series must be issued.

Acknowledgments

Thanks to the many helpful members of the FIND working group for
discussions leading to this specification.

Specific acknowledgment is given to Jeff Allen formerly of Bunyip
Information Systems. His original version of these documents helped
enormously in crystallizing the debate and consensus. Most of the
actual text in this document was originally authored by Jeff.

Authors' Addresses

Jeff R. Allen
246 Hawthorne St.
Palo Alto, CA 94301

EMail: jeff.allen@acm.org

Michael Mealling
Network Solutions, Inc.
505 Huntmar Park Drive
Herndon, VA 22070

Phone: +1-703-742-0400
EMail: michael.mealling@RWhois.net

References

[FRAMEWORK] Allen, J. and M. Mealling, "The Architecture of the
Common Indexing Protocol (CIP)", RFC2651, August 1999.

[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC2046,
January 1996.

[RFC2048] Freed, N., Klensin, J. and J. Postel, "Multipurpose
Internet Mail Extensions (MIME) Part Four: MIME
Registration Procedures", RFC2048, January 1996.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC2119, March 1997.

[RFC821] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC
821, August 1992.

Appendix A: Media Type Registration Templates

The following templates have been registered with the IANA:

Index tree

To: ietf-types@iana.org
Subject: Registration of MIME media type tree application/index

MIME media type name: application

MIME subtype name: index

Required parameters: none

Optional parameters: none

Encoding considerations: none

Security considerations:

Security considerations come into play in at least the following
two scenarios. Indexing information can leak undesirable amounts
of proprietary information, unless carefully controlled. At a more
fundamental level, the CIP protocol itself requires external
security services to operate in a safe manner. Both topics are
covered below.

Interoperability considerations:

Published specification:

RFC2652

Applications which use this media type:

This media type is used to contain information about indices and
how they inter-operate to form meshes of index servers.

Additional information:

This media type is not a standalone type. It is the top level of a
tree similar to the vnd or prs trees specified in Section 2.1 of
RFC2048. There are four specified branches to this tree:
application/index.cmd
application/index.response
application/index.obj
application/index.vnd

Each of these branches is a tree in its own right with types
registered below them. See those registrations for more
information on the types allowed below those branches.

Person & email address to contact for further information:

Intended usage: LIMITED USE

Author/Change controller:

Command tree

To: ietf-types@iana.org
Subject: Registration of MIME media type application/index.cmd

MIME media type name: application

MIME subtype name: index.cmd

Required parameters: none

Optional parameters: none

Encoding considerations: none

Security considerations:

Security considerations come into play in at least the following
two scenarios. Indexing information can leak undesirable amounts
of proprietary information, unless carefully controlled. At a more
fundamental level, the CIP protocol itself requires external
security services to operate in a safe manner. Both topics are
covered below.

Interoperability considerations:

Implementors should handle unknown commands gracefully.

Published specification:

RFC2652

Applications which use this media type:

This media type is the top of a tree of media types that express
commands between hosts that exchange indices for the purpose of
routing referrals.

Additional information:

This media type is not a standalone type. It is the top of a tree
similar to the vnd and prs trees specified in Section 2.1 of
RFC2048. Types registered within this tree are limited to being
commands as specified in the document(s) referenced in the
"Published specifications" section.

Person & email address to contact for further information:

Intended usage: LIMITED USE

Author/Change controller:

Response tree

To: ietf-types@iana.org
Subject: Registration of MIME media type application/index.response

MIME media type name: application

MIME subtype name: index.response

Required parameters: code

Optional parameters: none

Encoding considerations: none

Security considerations:

Security considerations come into play in at least the following
two scenarios. Indexing information can leak undesirable amounts
of proprietary information, unless carefully controlled. At a more
fundamental level, the CIP protocol itself requires external
security services to operate in a safe manner. Both topics are
covered below.

Interoperability considerations:

Implementors should handle unknown responses gracefully.

Published specification:

RFC2652

Applications which use this media type:

This media type is used to encode responses to CIP commands passed
between hosts that exchange indices for the purpose of routing
referrals.

Additional information:

This media type _is_ a standalone type. The code parameter
contains the specific response code as specified by Appendix B of
the specification document.

Person & email address to contact for further information:

Intended usage: LIMITED USE

Author/Change controller:

Index Object tree

To: ietf-types@iana.org
Subject: Registration of MIME media type application/index.obj

MIME media type name: application

MIME subtype name: index.obj

Required parameters: type, dsi, base-uri

Optional parameters: none

Encoding considerations: none

Security considerations:

Security considerations come into play in at least the following
two scenarios. Indexing information can leak undesirable amounts
of proprietary information, unless carefully controlled. At a more
fundamental level, the CIP protocol itself requires external
security services to operate in a safe manner. Both topics are
covered below.

Interoperability considerations:

Implementors should handle unknown index objects according to
rules specified in the published specification.

Published specification:

RFC2652

Applications which use this media type:

This media type is the top of a tree of media types that express
indexes that are exchanged between hosts that operate within a
referral mesh.

Additional information:

This media type is not a standalone type. It is the top of a tree
similar to the vnd and prs trees specified in Section 2.1 of
RFC2048. Types registered within this tree are limited to being
representations of indexes that contain some summary of the data
found in some database and is used to generate referrals as
specified in the above specified publication.

Person & email address to contact for further information:

Intended usage: LIMITED USE

Author/Change controller:

Vendor tree

To: ietf-types@iana.org
Subject: Registration of MIME media type application/index.vnd

MIME media type name: application

MIME subtype name: index.vnd

Required parameters: none

Optional parameters: none

Encoding considerations: none

Security considerations:

Security considerations come into play in at least the following
two scenarios. Indexing information can leak undesirable amounts
of proprietary information, unless carefully controlled. At a more
fundamental level, the CIP protocol itself requires external
security services to operate in a safe manner. Both topics are
covered below.

Interoperability considerations:

Implementors should handle unknown objects gracefully.

Published specification:

RFC2652

Applications which use this media type:

This media type is the top of a tree of media types that express
vendor specific extensions to the framework specified in the
published specifications.

Additional information:

This media type is not a standalone type. It is the top of a tree
similar to the vnd and prs trees specified in Section 2.1 of
RFC2048. Types registered within this tree are limited to being
vendor specific extensions to the CIP framework as specified in
the publications. Any registrations within this tree are still
limited to dealing with indexes, meshes and referrals.

Person & email address to contact for further information:

Intended usage: LIMITED USE

Appendix B: Response Codes

The meaning of the various digits in the response codes is discussed
in RFC-821, Appendix E.

The following response codes are defined for use by CIPv3 servers.
Implementors must use these exact codes; undefined codes should be
interpreted by CIP servers as fatal protocol errors. Instead of
defining new codes for unforeseen situations, implementors must adapt
one of the given codes. The implementation should attach a useful
alternative comment to the reused response code.

Code Suggested description text
Sender-CIP action
--------------------------------------------------------
220 Initial server banner message

300 Requested CIP version accepted
Continue with CIP transaction, in the specified
version.

222 Connection closing (in response to sender-CIP close)
Done with transaction.

200 MIME request received and processed
Expect no output, continue session (or close)

201 MIME request received and processed, output follows
Read a response, delimited by SMTP-style message
delimiter.

400 Temporarily unable to process request
Retry at a later time. May be used to indicate
that the server does not currently have the
resources available to accept an index.

500 Bad MIME message format
Retry with correctly formatted MIME request.

501 Unknown or missing request in application/index.cmd
Retry with correct CIP command.

502 Request is missing required CIP attributes
Retry with correct CIP attributes.

520 Aborting connection for some unexpected reason
Retry and/or alert local administrator.

530 Request requires valid signature
Sign the request, if possible, and retry.
Otherwise, report problem to the administrator.

531 Request has invalid signature
Report problem to the administrator.

532 Cannot check signature
Alert local administrator, who should cooperate with
remote administrator to diagnose and resolve the
problem. (Probably missing a public key.)

5. Full Copyright Statement

Copyright (C) The Internet Society (1999). All Rights Reserved.

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.

This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

Funding for the RFCEditor function is currently provided by the
Internet Society.

文章来源于领测软件测试网 https://www.ltesting.net/