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Network Working Group K. Moore Request for Comments: 3205 University of Tennessee BCP: 56 February 2002 Category: Best Current Practice

                 On the use of HTTP as a Substrate

Status of this Memo

 This document specifies an Internet Best Current Practices for the
 Internet Community, and requests discussion and suggestions for
 improvements.  Distribution of this memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (2002).  All Rights Reserved.


 Recently there has been widespread interest in using Hypertext
 Transfer Protocol (HTTP) as a substrate for other applications-level
 protocols.  This document recommends technical particulars of such
 use, including use of default ports, URL schemes, and HTTP security

1. Introduction

 Recently there has been widespread interest in using Hypertext
 Transfer Protocol (HTTP) [1] as a substrate for other applications-
 level protocols.  Various reasons cited for this interest have
 o  familiarity and mindshare,
 o  compatibility with widely deployed browsers,
 o  ability to reuse existing servers and client libraries,
 o  ease of prototyping servers using CGI scripts and similar
    extension mechanisms,
 o  ability to use existing security mechanisms such as HTTP digest
    authentication [2] and SSL or TLS [3],
 o  the ability of HTTP to traverse firewalls, and
 o  cases where a server often needs to support HTTP anyway.

Moore Best Current Practice [Page 1] RFC 3205 HTTP Layering February 2002

 The Internet community has a long tradition of protocol reuse, dating
 back to the use of Telnet [4] as a substrate for FTP [5] and SMTP
 [6].  However, the recent interest in layering new protocols over
 HTTP has raised a number of questions when such use is appropriate,
 and the proper way to use HTTP in contexts where it is appropriate.
 Specifically, for a given application that is layered on top of HTTP:
 o  Should the application use a different port than the HTTP default
    of 80?
 o  Should the application use traditional HTTP methods (GET, POST,
    etc.) or should it define new methods?
 o  Should the application use http: URLs or define its own prefix?
 o  Should the application define its own MIME-types, or use something
    that already exists (like registering a new type of MIME-directory
 This memo recommends certain design decisions in answer to these
 This memo is intended as advice and recommendation for protocol
 designers, working groups, implementors, and IESG, rather than as a
 strict set of rules which must be adhered to in all cases.
 Accordingly, the capitalized key words defined in RFC 2119, which are
 intended to indicate conformance to a specification, are not used in
 this memo.

2. Issues Regarding the Design Choice to use HTTP

 Despite the advantages listed above, it's worth asking the question
 as to whether HTTP should be used at all, or whether the entire HTTP
 protocol should be used.

2.1 Complexity

 HTTP started out as a simple protocol, but quickly became much more
 complex due to the addition of several features unanticipated by its
 original design.  These features include persistent connections, byte
 ranges, content negotiation, and cache support.  All of these are
 useful for traditional web applications but may not be useful for the
 layered application.  The need to support (or circumvent) these
 features can add additional complexity to the design and
 implementation of a protocol layered on top of HTTP.  Even when HTTP
 can be "profiled" to minimize implementation overhead, the effort of
 specifying such a profile might be more than the effort of specifying
 a purpose-built protocol which is better suited to the task at hand.

Moore Best Current Practice [Page 2] RFC 3205 HTTP Layering February 2002

 Even if existing HTTP client and server code can often be re-used,
 the additional complexity of layering something over HTTP vs. using a
 purpose-built protocol can increase the number of interoperability

2.2 Overhead

 Further, although HTTP can be used as the transport for a "remote
 procedure call" paradigm, HTTP's protocol overhead, along with the
 connection setup overhead of TCP, can make HTTP a poor choice.  A
 protocol based on UDP, or with both UDP and TCP variants, should be
 considered if the payloads are very likely to be small (less than a
 few hundred bytes) for the foreseeable future.  This is especially
 true if the protocol might be heavily used, or if it might be used
 over slow or expensive links.
 On the other hand, the connection setup overhead can become
 negligible if the layered protocol can utilize HTTP/1.1's persistent
 connections, and if the same client and server are likely to perform
 several transactions during the time the HTTP connection is open.

2.3 Security

 Although HTTP appears at first glance to be one of the few "mature"
 Internet protocols that can provide good security, there are many
 applications for which neither HTTP's digest authentication nor TLS
 are sufficient by themselves.
 Digest authentication requires a secret (e.g., a password) to be
 shared between client and server.  This further requires that each
 client know the secret to be used with each server, but it does not
 provide any means of securely transmitting such secrets between the
 parties.  Shared secrets can work fine for small groups where
 everyone is physically co-located; they don't work as well for large
 or dispersed communities of users.  Further, if the server is
 compromised a large number of secrets may be exposed, which is
 especially dangerous if the same secret (or password) is used for
 several applications.  (Similar concerns exist with TLS based clients
 or servers - if a private key is compromised then the attacker can
 impersonate the party whose key it has.)
 TLS and its predecessor SSL were originally designed to authenticate
 web servers to clients, so that a user could be assured (for example)
 that his credit card number was not being sent to an imposter.
 However, many applications need to authenticate clients to servers,
 or to provide mutual authentication of client and server.  TLS does

Moore Best Current Practice [Page 3] RFC 3205 HTTP Layering February 2002

 have a capability to provide authentication in each direction, but
 such authentication may or may not be suitable for a particular
 Web browsers which support TLS or SSL are typically shipped with the
 public keys of several certificate authorities (CAs) "wired in" so
 that they can verify the identity of any server whose public key was
 signed by one of those CAs.  For this to work well, every secure web
 server's public key has to be signed by one of the CAs whose keys are
 wired into popular browsers.  This deployment model works when there
 are a (relatively) small number of servers whose identities can be
 verified, and their public keys signed, by the small number of CAs
 whose keys are included in a small number of different browsers.
 This scheme does not work as well to authenticate millions of
 potential clients to servers.  It would take a much larger number of
 CAs to do the job, each of which would need to be widely trusted by
 servers.  Those CAs would also have a more difficult time verifying
 the identities of (large numbers of) ordinary users than they do in
 verifying the identities of (a smaller number of) commercial and
 other enterprises that need to run secure web servers.
 Also, in a situation where there were a large number of clients
 authenticating with TLS, it seems unlikely that there would be a set
 of CAs whose keys were trusted by every server.  A client that
 potentially needed to authenticate to multiple servers would
 therefore need to be configured as to which key to use with which
 server when attempting to establish a secure connection to the
 For the reasons stated above, client authentication is rarely used
 with TLS.  A common technique is to use TLS to authenticate the
 server to the client and to establish a private channel, and for the
 client to authenticate to the server using some other means - for
 example, a username and password using HTTP basic or digest
 For any application that requires privacy, the 40-bit ciphersuites
 provided by some SSL implementations (to conform to outdated US
 export regulations or to regulations on the use or export of
 cryptography in other countries) are unsuitable.  Even 56-bit DES
 encryption, which is required of conforming TLS implementations, has
 been broken in a matter of days with a modest investment in
 resources.  So if TLS is chosen it may be necessary to discourage use
 of small key lengths, or of weak ciphersuites, in order to provide
 adequate privacy assurance.  If TLS is used to provide privacy for
 passwords sent by clients then it is especially important to support
 longer keys.

Moore Best Current Practice [Page 4] RFC 3205 HTTP Layering February 2002

 None of the above should be taken to mean that either digest
 authentication or TLS are generally inferior to other authentication
 systems, or that they are unsuitable for use in other applications
 besides HTTP.  Many of the limitations of TLS and digest
 authentication also apply to other authentication and privacy
 systems.  The point here is that neither TLS nor digest
 authentication is a "magic pixie dust" solution to authentication or
 privacy.  In every case, an application's designers must carefully
 determine the application's users' requirements for authentication
 and privacy before choosing an authentication or privacy mechanism.
 Note also that TLS can be used with other TCP-based protocols, and
 there are SASL [7] mechanisms similar to HTTP's digest
 authentication.  So it is not necessary to use HTTP in order to
 benefit from either TLS or digest-like authentication.  However, HTTP
 APIs may already support TLS and/or digest.

2.4 Compatibility with Proxies, Firewalls, and NATs

 One oft-cited reason for the use of HTTP is its ability to pass
 through proxies, firewalls, or network address translators (NATs).
 One unfortunate consequence of firewalls and NATs is that they make
 it harder to deploy new Internet applications, by requiring explicit
 permission (or even a software upgrade of the firewall or NAT) to
 accommodate each new protocol.  The existence of firewalls and NATs
 creates a strong incentive for protocol designers to layer new
 applications on top of existing protocols, including HTTP.
 However, if a site's firewall prevents the use of unknown protocols,
 this is presumably a conscious policy decision on the part of the
 firewall administrator.  While it is arguable that such policies are
 of limited value in enhancing security, this is beside the point -
 well-known port numbers are quite useful for a variety of purposes,
 and the overloading of port numbers erodes this utility.  Attempting
 to circumvent a site's security policy is not an acceptable
 justification for doing so.
 It would be useful to establish guidelines for "firewall-friendly"
 protocols, to make it easier for existing firewalls to be compatible
 with new protocols.

2.5 Questions to be asked when considering use of HTTP

 o  When considering payload size and traffic patterns, is HTTP an
    appropriate transport for the anticipated use of this protocol?

Moore Best Current Practice [Page 5] RFC 3205 HTTP Layering February 2002

    (In other words: will the payload size be worth the overhead
    associated with TCP and HTTP?  Or will the application be able to
    make use of HTTP persistent connections to amortize the cost of
    that overhead over several requests?)
 o  Is this new protocol usable by existing web browsers without
    (For example: Is the request transmitted as if it were a filled-in
    HTML form?  Is the response which is returned viewable from a web
    browser, say as HTML?)
 o  Are the existing HTTP security mechanisms appropriate for the new
 o  Are HTTP status codes and the HTTP status code paradigm suitable
    for this application?  (see section 8)
 o  Does the server for this application need to support HTTP anyway?

3. Issues Regarding Reuse of Port 80

 IANA has reserved TCP port number 80 for use by HTTP.  It would not
 be appropriate for a substantially new service, even one which uses
 HTTP as a substrate, to usurp port 80 from its traditional use.  A
 new use of HTTP might be considered a "substantially new service",
 thus requiring a new port, if any of the following are true:
 o  The "new service" and traditional HTTP service are likely to
    reference different sets of data, even when they both operate on
    the same host.
 o  There is a good reason for the "new service" to be implemented by
    a separate server process, or separate code, than traditional HTTP
    service on the same host, at least on some platforms.
 o  There is a good reason to want to easily distinguish the traffic
    of the "new service" from traditional HTTP, e.g., for the purposes
    of firewall access control or traffic analysis.
 o  If none of the above are true, it is arguable that the new use of
    HTTP is an "extension" to traditional HTTP, rather than a "new
    service".  Extensions to HTTP which share data with traditional
    HTTP services should probably define new HTTP methods to describe
    those extensions, rather than using separate ports.  If separate
    ports are used, there is no way for a client to know whether they
    are separate services or different ways of accessing the same
    underlying service.

Moore Best Current Practice [Page 6] RFC 3205 HTTP Layering February 2002

4. Issues Regarding Reuse of the http: Scheme in URLs

 A number of different URL schemes are in widespread use and many more
 are in the process of being standardized.  In practice, the URL
 scheme not only serves as a "tag" to govern the interpretation of the
 remaining portion of the URL, it also provides coarse identification
 of the kind of resource or service which is being accessed.  For
 example, web browsers typically provide a different response when a
 user mouse-clicks on an "http" URL, than when the user clicks on a
 "mailto" URL.
 Some criteria that might be used in making this determination are:
 o  Whether this URL scheme is likely to become widely used, versus
    used only in limited communities or by private agreement.
 o  Whether a new "default port" is needed.  If reuse of port 80 is
    not appropriate (see above), a new "default port" is needed.  A
    new default port in turn requires that a new URL scheme be
    registered if that URL scheme is expected to be widely used.
    Explicit port numbers in URLs are regarded as an "escape hatch",
    not something for use in ordinary circumstances.
 o  Whether use of the new service is likely to require a
    substantially different setup or protocol interaction with the
    server, than ordinary HTTP service.  This could include the need
    to request a different type of service from the network, or to
    reserve bandwidth, or to present different TLS authentication
    credentials to the server, or different kind of server
    provisioning, or any number of other needs.
 o  Whether user interfaces (such as web browsers) are likely to be
    able to exploit the difference in the URL prefix to produce a
    significant improvement in usability.
 According to the rules in [8] the "http:" URI is part of the "IETF
 Tree" for URL scheme names, and IETF is the maintainer of the "IETF
 Tree".  Since IESG is the decision-making body for IETF, IESG has the
 authority to determine whether a resource accessed by a protocol that
 is layered on top of HTTP, should use http: or some other URL prefix.
 Note that the convention of appending an "s" to the URL scheme to
 mean "use TLS or SSL" (as in "http:" vs "https:") is nonstandard and
 of limited value.  For most applications, a single "use TLS or SSL"
 bit is not sufficient to adequately convey the information that a
 client needs to authenticate itself to a server, even if it has the
 proper credentials.  For instance, in order to ensure that adequate
 security is provided with TLS an application may need to be

Moore Best Current Practice [Page 7] RFC 3205 HTTP Layering February 2002

 configured with a list of acceptable ciphersuites, or with the client
 certificate to be used to authenticate to a particular server.  When
 it is necessary to specify authentication or other connection setup
 information in a URL these should be communicated in URL parameters,
 rather than in the URL prefix.

5. Issues regarding use of MIME media types

 Since HTTP uses the MIME media type system [9] to label its payload,
 many applications which layer on HTTP will need to define, or select,
 MIME media types for use by that application.  Especially when using
 a multipart structure, the choice of media types requires careful
 consideration.  In particular:
 o  Should some existing framework be used, such as text/directory
    [10], or XML [11,12], or should the new content-types be built
    from scratch?  Just as with HTTP, it's useful if code can be
    reused, but protocol designers should not be over-eager to
    incorporate a general but complex framework into a new protocol.
    Experience with ASN.1, for example, suggests that the advantage of
    using a general framework may not be worth the cost.
 o  Should MIME multipart or message types be allowed?  This can be an
    advantage if it is desirable to incorporate (for example) the
    multipart/alternative construct or the MIME security framework.
    On the other hand, these constructs were designed specifically for
    use in store-and-forward electronic mail systems, and other
    mechanisms may be more appropriate for the application being
    The point here is that a decision to use MIME content-type names
    to describe protocol payloads (which is generally desirable if the
    same payloads may appear in other applications) does not imply
    that the application must accept arbitrary MIME content-types,
    including MIME multipart or security mechanisms.  Nor does it
    imply that the application must use MIME syntax or that it must
    recognize or even tolerate existing MIME header fields.
 o  If the same payload is likely to be sent over electronic mail, the
    differences between HTTP encoding of the payload and email
    encoding of the payload should be minimized.  Ideally, there
    should be no differences in the "canonical form" used in the two
    environments.  Text/* media types can be problematic in this
    regard because MIME email requires CRLF for line endings of text/*
    body parts, where HTTP traditionally uses LF only.

Moore Best Current Practice [Page 8] RFC 3205 HTTP Layering February 2002

 o  A MIME content-type label describes the nature of the object being
    labeled.  It does not describe, and should not be used to
    describe, the semantics which should be applied when the object is
    received.  For instance, the transmission of an object with a
    particular content-type using HTTP POST, should not be taken as a
    request for some operation based solely on the type.  The request
    should be separate from the content-type label and it should be
    When it is necessary for a protocol layered on HTTP to allow
    different operations on the same type of object, this can be
    communicated in a number of different ways: HTTP methods, HTTP
    request-URI, HTTP request headers, the MIME Content-Disposition
    header field, or as part of the payload.

6. Issues Regarding Existing vs. New HTTP Methods

 It has been suggested that a new service layered on top of HTTP
 should define one or more new HTTP methods, rather than allocating a
 new port.  The use of new methods may be appropriate, but is not
 sufficient in all cases.  The definition of one or more new methods
 for use in a new protocol, does not by itself alleviate the need for
 use of a new port, or a new URL type.

7. Issues regarding reuse of HTTP client, server, and proxy code

 As mentioned earlier, one of the primary reasons for the use of HTTP
 as a substrate for new protocols, is to allow reuse of existing HTTP
 client, server, or proxy code.  However, HTTP was not designed for
 such layering.  Existing HTTP client and code may have "http"
 assumptions wired into them.  For instance, client libraries and
 proxies may expect "http:" URLs, and clients and servers may send
 (and expect) "HTTP/1.1", in requests and responses, as opposed to the
 name of the layered protocol and its version number.
 Existing client libraries may not understand new URL types.  In order
 to get a new HTTP-layered application client to work with an existing
 client library, it may be necessary for the application to convert
 its URLs to an "http equivalent" form.  For instance, if service
 "xyz" is layered on top of HTTP using port ###, the xyz client may
 need, when invoking an HTTP client library, to translate its URLs
 from "xyz://host/something" format to "http://host:###/something" for
 the purpose of calling that library.  This should be done ONLY when
 calling the HTTP client library - such URLs should not be used in
 other parts of the protocol, nor should they be exposed to users.

Moore Best Current Practice [Page 9] RFC 3205 HTTP Layering February 2002

 Note that when a client is sending requests directly to an origin
 server, the URL prefix ("http:") is not normally sent.  So
 translating xyz: URLs to http: URLs when calling the client library
 should not actually cause http: URLs to be sent over the wire.  But
 when the same client is sending requests to a proxy server, the
 client will normally send the entire URL (including the http: prefix)
 in those requests.  The proxy will remove the http: prefix when the
 request is communicated to the origin server.
 Existing HTTP client libraries and servers will transmit "HTTP/1.1"
 (or a different version) in requests and responses.  To facilitate
 reuse of such libraries and servers by a new protocol, such a
 protocol may therefore need to transmit and accept "HTTP/1.1" rather
 than its own protocol name and version number.  Designers of
 protocols which are layered on top of HTTP should explicitly choose
 whether or not to accept "HTTP/1.1" in protocol exchanges.
 For certain applications it may be necessary to require or limit use
 of certain HTTP features, for example, to defeat caching of responses
 by proxies.  Each protocol layered on HTTP must therefore specify the
 specific way that HTTP will be used, and in particular, how the
 client and server should interact with HTTP proxies.

8. Issues regarding use of HTTP status codes

 HTTP's three-digit status codes were designed for use with
 traditional HTTP applications (e.g., document retrieval, forms-based
 queries), and are unlikely to be suitable to communicate the
 specifics of errors encountered in dissimilar applications.  Even
 when it seems like there is a close match between HTTP status codes
 and the codes needed by the application, experience with reuse of
 other protocols indicates that subtle variations in usage are likely;
 and that this is likely to degrade interoperability of both the
 original protocol (in this case HTTP) and any layered applications.
 HTTP status codes therefore should not be used to indicate subtle
 errors of layered applications.  At most, the "generic" HTTP codes
 200 (for complete success) and 500 (for complete failure) should be
 used to indicate errors resulting from the content of the request
 message-body.  Under certain circumstances, additional detail about
 the nature of the error can then be included in the response
 message-body.  Other status codes than 200 or 500 should only appear
 if the error was detected by the HTTP server or by an intermediary.
 A layered application should not define new HTTP status codes.  The
 set of available status codes is small, conflicts in code assignment
 between different layered applications are likely, and they may be
 needed by future versions of, or extensions to, mainstream HTTP.

Moore Best Current Practice [Page 10] RFC 3205 HTTP Layering February 2002

 Use of HTTP's error codes is problematic when the layered application
 does not share same notion of success or failure as HTTP.  The
 problem exists when the client does not connect directly to the
 origin server, but via one or more HTTP caches or proxies.  (Since
 the ability of HTTP to communicate through intermediaries is often
 the primary motivation for reusing HTTP, the ability of the
 application to operate in the presence of such intermediaries is
 considered very important.)  Such caches and proxies will interpret
 HTTP's error codes and may take additional action based on those
 codes.  For instance, on receipt of a 200 error code from an origin
 server (and under other appropriate conditions) a proxy may cache the
 response and re-issue it in response to a similar request.  Or a
 proxy may modify the result of a request which returns a 500 error
 code in order to add a "helpful" error message.  Other response codes
 may produce other behaviors.
 A few guidelines are therefore in order:
 o  A layered application should use appropriate HTTP error codes to
    report errors resulting from information in the HTTP request-line
    and header fields associated with the request.  This request
    information is part of the HTTP protocol and errors which are
    associated with that information should therefore be reported
    using HTTP protocol mechanisms.
 o  A layered application for which all errors resulting from the
    message-body can be classified as either "complete success" or
    "complete failure" may use 200 and 500 for those conditions,
    respectively.  However, the specification for such an application
    must define the mechanism which ensures that its successful (200)
    responses are not cached by intermediaries, or demonstrate that
    such caching will do no harm; and it must be able to operate even
    if the message-body of an error (500) response is not transmitted
    back to the client intact.
 o  A layered application may return a 200 response code for both
    successfully processed requests and errors (or other exceptional
    conditions) resulting from the request message-body (but not from
    the request headers).  Such an application must return its error
    code as part of the response message body, and the specification
    for that application protocol must define the mechanism by which
    the application ensures that its responses are not cached by
    intermediaries.  In this case a response other than 200 should be
    used only to indicate errors with, or the status of, the HTTP
    protocol layer (including the request headers), or to indicate the
    inability of the HTTP server to communicate with the application

Moore Best Current Practice [Page 11] RFC 3205 HTTP Layering February 2002

 o  A layered application which cannot operate in the presence of
    intermediaries or proxies that cache and/or alter error responses,
    should not use HTTP as a substrate.

9. Summary of recommendations regarding reuse of HTTP

 1. All protocols should provide adequate security.  The security
    needs of a particular application will vary widely depending on
    the application and its anticipated use environment.  Merely using
    HTTP and/or TLS as a substrate for a protocol does not
    automatically provide adequate security for all environments, nor
    does it relieve the protocol developers of the need to analyze
    security considerations for their particular application.
 2. New protocols - including but not limited to those using HTTP -
    should not attempt to circumvent users' firewall policies,
    particularly by masquerading as existing protocols.
    "Substantially new services" should not reuse existing ports.
 3. In general, new protocols or services should not reuse http: or
    other URL schemes.
 4. Each new protocol specification that uses HTTP as a substrate
    should describe the specific way that HTTP is to be used by that
    protocol, including how the client and server interact with
 5. New services should follow the guidelines in section 8 regarding
    use of HTTP status codes.

10. Security Considerations

 Much of this document is about security.  Section 2.3 discusses
 whether HTTP security is adequate for the needs of a particular
 application, section 2.4 discusses interactions between new HTTP-
 based protocols and firewalls, section 3 discusses use of separate
 ports so that firewalls are not circumvented, and section 4 discusses
 the inadequacy of the "s" suffix of a URL prefix for specifying
 security levels.

11. References

 [1]   Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,
       Leach, P. and T. Berners-Lee, "Hypertext Transfer Protocol --
       HTTP/1.1", RFC 2616, June 1999.

Moore Best Current Practice [Page 12] RFC 3205 HTTP Layering February 2002

 [2]   Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S.,
       Leach, P., Luotonen, A. and L. Stewart, "HTTP Authentication:
       Basic and Digest Access Authentication", RFC 2617, June 1999.
 [3]   Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", RFC
       2246, January 1999.
 [4]   Postel, J. and J. Reynolds, "Telnet Protocol Specification",
       STD 8, RFC 854, May 1983.
 [5]   Postel, J. and J. Reynolds, "File Transfer Protocol", STD 9,
       RFC 959, October 1985.
 [6]   Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April
 [7]   Myers, J., "Simple Authentication and Security Layer (SASL)",
       RFC 2222, October 1997.
 [8]   Petke, R. and I. King, "Registration Procedures for URL Scheme
       Names", BCP 35, RFC 2717, November 1999.
 [9]   Freed, N. and N. Borenstein, "Multipurpose Internet Mail
       Extensions (MIME) Part Two: Media Types", RFC 2046, November
 [10]  Howes, T., Smith, M. and F. Dawson, "A MIME Content-Type for
       Directory Information", RFC 2425, September 1998.
 [11]  Bray, T., Paoli, J. and C. Sperberg-McQueen, "Extensible Markup
       Language (XML)" World Wide Web Consortium Recommendation REC-
       xml-19980210, February 1998.
 [12]  Murata, M., St. Laurent, S. and D. Kohn, "XML Media Types", RFC
       3023, January 2001.

12. Author's Address

 Keith Moore
 University of Tennessee
 Computer Science Department
 1122 Volunteer Blvd, Suite 203
 Knoxville TN, 37996-3450

Moore Best Current Practice [Page 13] RFC 3205 HTTP Layering February 2002

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 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


 Funding for the RFC Editor function is currently provided by the
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Moore Best Current Practice [Page 14]

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