11.  Formal Syntax

   The following syntax specification uses XML Schema as described in
   XML [7].

11.1.  Schema

   <?xml version="1.0" encoding="UTF-8"?>
   <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
     elementFormDefault="qualified">
     <xs:element name="MediaServerControl">
       <xs:complexType>
         <xs:choice>
           <xs:element name="request">
             <xs:complexType>
               <xs:choice>
                 <xs:element name="configure_conference"
                   type="configure_conferenceRequestType"/>
                 <xs:element name="configure_leg"
                   type="configure_legRequestType"/>
                 <xs:element name="play" type="playRequestType"/>
                 <xs:element name="playcollect"
                   type="playcollectRequestType"/>
                 <xs:element name="playrecord"
                   type="playrecordRequestType"/>

                 <xs:element name="managecontent"
                   type="managecontentRequestType"/>
                 <xs:element name="faxplay"
                   type="faxRequestType"/>
                 <xs:element name="faxrecord"
                   type="faxRequestType"/>
                 <xs:element name="stop" type="stopRequestType"/>
               </xs:choice>
             </xs:complexType>
           </xs:element>
           <xs:element name="response" type="responseType"/>
           <xs:element name="notification">
             <xs:complexType>
               <xs:choice>
                 <xs:element name="conference"
                   type="conferenceNotificationType"/>
                 <xs:element name="keypress"
                   type="keypressNotificationType"/>
                 <xs:element name="signal"
                   type="signalNotificationType"/>
               </xs:choice>
             </xs:complexType>
           </xs:element>
         </xs:choice>
         <xs:attribute name="version" use="required"/>
       </xs:complexType>
     </xs:element>
     <!-- Definitions for base and concrete MSCML requests -->
     <!-- and embedded types. -->
     <xs:complexType name="base_requestType" abstract="true">
       <xs:attribute name="id" type="xs:string"/>
     </xs:complexType>
     <xs:complexType name="playRequestType">
       <xs:complexContent>
         <xs:extension base="base_requestType">
           <xs:sequence>
             <xs:element name="prompt" type="promptType"
               minOccurs="0"/>
           </xs:sequence>
           <xs:attribute name="prompturl" type="xs:string"/>
           <xs:attribute name="offset" type="xs:string"/>
           <xs:attribute name="promptencoding" type="xs:string"/>
         </xs:extension>
       </xs:complexContent>
     </xs:complexType>
     <xs:complexType name="configure_conferenceRequestType">
       <xs:complexContent>
         <xs:extension base="base_requestType">

           <xs:sequence>
             <xs:element name="subscribe"
               type="conference_eventsubscriptionType" minOccurs="0"/>
           </xs:sequence>
           <xs:attribute name="reservedtalkers"
             type="xs:positiveInteger"/>
           <xs:attribute name="reserveconfmedia" type="yesnoType"
             default="yes"/>
         </xs:extension>
       </xs:complexContent>
     </xs:complexType>
     <xs:complexType name="configure_legRequestType">
       <xs:complexContent>
         <xs:extension base="base_requestType">
           <xs:sequence>
             <xs:element name="inputgain" type="gainType"
               minOccurs="0"/>
             <xs:element name="outputgain" type="gainType"
               minOccurs="0"/>
             <xs:element name="configure_team"
               type="configure_teamType" minOccurs="0"/>
             <xs:element name="subscribe"
               type="leg_eventsubscriptionType" minOccurs="0"/>
           </xs:sequence>
           <xs:attribute name="type">
             <xs:simpleType>
               <xs:restriction base="xs:NMTOKEN">
                 <xs:enumeration value="talker"/>
                 <xs:enumeration value="listener"/>
               </xs:restriction>
             </xs:simpleType>
           </xs:attribute>
           <xs:attribute name="mixmode">
             <xs:simpleType>
               <xs:restriction base="xs:NMTOKEN">
                 <xs:enumeration value="full"/>
                 <xs:enumeration value="mute"/>
                 <xs:enumeration value="preferred"/>
                 <xs:enumeration value="parked"/>
                 <xs:enumeration value="private"/>
               </xs:restriction>
             </xs:simpleType>
           </xs:attribute>
           <xs:attribute name="dtmfclamp" type="yesnoType"/>
           <xs:attribute name="toneclamp" type="yesnoType"/>
         </xs:extension>
       </xs:complexContent>
     </xs:complexType>

     <xs:complexType name="configure_teamType">
       <xs:sequence>
         <xs:element name="teammate" type="teammateType" minOccurs="0"
           maxOccurs="unbounded"/>
       </xs:sequence>
       <xs:attribute name="id" type="xs:string"/>
       <xs:attribute name="action" use="required">
         <xs:simpleType>
           <xs:restriction base="xs:string">
             <xs:enumeration value="add"/>
             <xs:enumeration value="delete"/>
             <xs:enumeration value="query"/>
             <xs:enumeration value="set"/>
           </xs:restriction>
         </xs:simpleType>
       </xs:attribute>
     </xs:complexType>
     <xs:complexType name="teammateType">
       <xs:attribute name="id" type="xs:string" use="required"/>
     </xs:complexType>
     <xs:complexType name="playcollectRequestType">
       <xs:complexContent>
         <xs:extension base="base_requestType">
           <xs:sequence>
             <xs:element name="prompt" type="promptType"
               minOccurs="0"/>
             <xs:element name="pattern" type="dtmfGrammarType"
               minOccurs="0"/>
           </xs:sequence>
           <xs:attribute name="prompturl" type="xs:string"/>
           <xs:attribute name="offset" type="xs:string"/>
           <xs:attribute name="barge" type="yesnoType" default="yes"/>
           <xs:attribute name="promptencoding" type="xs:string"/>
           <xs:attribute name="cleardigits" type="yesnoType"
             default="no"/>
           <xs:attribute name="maxdigits" type="xs:string"/>
           <xs:attribute name="firstdigittimer" type="xs:string"
             default="5000ms"/>
           <xs:attribute name="interdigittimer" type="xs:string"
             default="2000ms"/>
           <xs:attribute name="extradigittimer" type="xs:string"
             default="1000ms"/>
           <xs:attribute name="interdigitcriticaltimer"
             type="xs:string"/>
           <xs:attribute name="skipinterval" type="xs:string"
             default="6s"/>
           <xs:attribute name="ffkey" type="DTMFkeyType"/>
           <xs:attribute name="rwkey" type="DTMFkeyType"/>

           <xs:attribute name="returnkey" type="DTMFkeyType"
             default="#"/>
           <xs:attribute name="escapekey" type="DTMFkeyType"
             default="*"/>
           <xs:attribute name="maskdigits" type="yesnoType"
             default="no"/>
         </xs:extension>
       </xs:complexContent>
     </xs:complexType>
     <xs:complexType name="playrecordRequestType">
       <xs:complexContent>
         <xs:extension base="base_requestType">
           <xs:sequence>
             <xs:element name="prompt" type="promptType"
               minOccurs="0"/>
           </xs:sequence>
           <xs:attribute name="prompturl" type="xs:string"/>
           <xs:attribute name="promptencoding" type="xs:string"/>
           <xs:attribute name="offset" type="xs:string" default="0"/>
           <xs:attribute name="barge" type="yesnoType" default="yes"/>
           <xs:attribute name="cleardigits" type="yesnoType"
             default="no"/>
           <xs:attribute name="escapekey" type="xs:string" default="*"/>
           <xs:attribute name="recurl" type="xs:string" use="required"/>
           <xs:attribute name="mode" default="overwrite">
             <xs:simpleType>
               <xs:restriction base="xs:NMTOKEN">
                 <xs:enumeration value="append"/>
                 <xs:enumeration value="overwrite"/>
               </xs:restriction>
             </xs:simpleType>
           </xs:attribute>
           <xs:attribute name="recencoding" type="xs:string"/>
           <xs:attribute name="initsilence" type="xs:string"/>
           <xs:attribute name="endsilence" type="xs:string"/>
           <xs:attribute name="duration" type="xs:string"/>
           <xs:attribute name="beep" type="yesnoType" default="yes"/>
           <xs:attribute name="recstopmask" type="xs:string"
             default="01234567890*#"/>
         </xs:extension>
       </xs:complexContent>
     </xs:complexType>
     <xs:complexType name="managecontentRequestType">
       <xs:complexContent>
         <xs:extension base="base_requestType">
           <xs:attribute name="fetchtimeout" type="xs:string"
             default="10000"/>
           <xs:attribute name="mimetype" type="xs:string"/>

           <xs:attribute name="name" type="xs:string"/>
           <xs:attribute name="httpmethod">
             <xs:simpleType>
               <xs:restriction base="xs:NMTOKEN">
                 <xs:enumeration value="put"/>
                 <xs:enumeration value="post"/>
               </xs:restriction>
             </xs:simpleType>
           </xs:attribute>
           <xs:attribute name="action">
             <xs:simpleType>
               <xs:restriction base="xs:NMTOKEN">
                 <xs:enumeration value="move"/>
                 <xs:enumeration value="delete"/>
               </xs:restriction>
             </xs:simpleType>
           </xs:attribute>
           <xs:attribute name="dest" type="xs:string"/>
           <xs:attribute name="src" type="xs:string" use="required"/>
         </xs:extension>
       </xs:complexContent>
     </xs:complexType>
     <xs:complexType name="stopRequestType">
       <xs:complexContent>
         <xs:extension base="base_requestType"/>
       </xs:complexContent>
     </xs:complexType>
     <xs:complexType name="faxRequestType">
       <xs:complexContent>
         <xs:extension base="base_requestType">
           <xs:sequence>
             <xs:element name="prompt" type="promptType" minOccurs="0"/>
           </xs:sequence>
           <xs:attribute name="lclid" type="xs:string"/>
           <xs:attribute name="prompturl" type="xs:string"/>
           <xs:attribute name="recurl" type="xs:string"/>
           <xs:attribute name="rmtid" type="xs:string"/>
         </xs:extension>
       </xs:complexContent>
     </xs:complexType>
     <xs:complexType name="dtmfGrammarType">
       <xs:choice>
         <xs:element name="regex" type="dtmfPatternType"
           maxOccurs="unbounded"/>
         <xs:element name="mgcpdigitmap" type="dtmfPatternType"/>
         <xs:element name="megacodigitmap" type="dtmfPatternType"/>
       </xs:choice>
     </xs:complexType>

     <xs:complexType name="dtmfPatternType">
       <xs:attribute name="value" type="xs:string" use="required"/>
       <xs:attribute name="name" type="xs:string"/>
     </xs:complexType>
     <!-- Definitions for base and concrete MSCML responses -->
     <!-- and embedded types. -->
     <xs:complexType name="base_responseType" abstract="true">
       <xs:attribute name="request" use="required">
         <xs:simpleType>
           <xs:restriction base="xs:NMTOKEN">
             <xs:enumeration value="configure_conference"/>
             <xs:enumeration value="configure_leg"/>
             <xs:enumeration value="play"/>
             <xs:enumeration value="playcollect"/>
             <xs:enumeration value="playrecord"/>
             <xs:enumeration value="managecontent"/>
             <xs:enumeration value="faxplay"/>
             <xs:enumeration value="faxrecord"/>
             <xs:enumeration value="stop"/>
           </xs:restriction>
         </xs:simpleType>
       </xs:attribute>
       <xs:attribute name="id" type="xs:string"/>
       <xs:attribute name="code" type="xs:string" use="required"/>
       <xs:attribute name="text" type="xs:string" use="required"/>
     </xs:complexType>
     <xs:complexType name="responseType">
       <xs:complexContent>
         <xs:extension base="base_responseType">
           <xs:sequence>
             <xs:element name="error_info"
               type="stoponerrorResponseType" minOccurs="0"/>
             <xs:element name="team" type="configure_teamResponseType"
               minOccurs="0"/>
           </xs:sequence>
           <xs:attribute name="reason" type="xs:string"/>
           <xs:attribute name="reclength" type="xs:string"/>
           <xs:attribute name="recduration" type="xs:string"/>
           <xs:attribute name="digits" type="xs:string"/>
           <xs:attribute name="name" type="xs:string"/>
           <xs:attribute name="playduration" type="xs:string"/>
           <xs:attribute name="playoffset" type="xs:string"/>
           <xs:attribute name="faxcode" type="xs:string"/>
           <xs:attribute name="pages_sent" type="xs:string"/>
           <xs:attribute name="pages_recv" type="xs:string"/>
         </xs:extension>
       </xs:complexContent>
     </xs:complexType>

     <xs:complexType name="stoponerrorResponseType">
       <xs:attribute name="code" type="xs:string" use="required"/>
       <xs:attribute name="text" type="xs:string" use="required"/>
       <xs:attribute name="context" type="xs:string" use="required"/>
     </xs:complexType>
     <xs:complexType name="configure_teamResponseType">
       <xs:sequence>
         <xs:element name="teammate" type="teammateType" minOccurs="0"
           maxOccurs="unbounded"/>
       </xs:sequence>
       <xs:attribute name="id" type="xs:string" use="required"/>
       <xs:attribute name="numteam" type="xs:integer" use="required"/>
     </xs:complexType>
     <!-- Definitions for MSCML event subscriptions and -->
     <!-- embedded types -->
     <xs:complexType name="conference_eventsubscriptionType">
       <xs:sequence>
         <xs:element name="events">
           <xs:complexType>
             <xs:sequence>
               <xs:element name="activetalkers"
                 type="activetalkersSubscriptionType"/>
             </xs:sequence>
           </xs:complexType>
         </xs:element>
       </xs:sequence>
     </xs:complexType>
     <xs:complexType name="activetalkersSubscriptionType">
       <xs:attribute name="report" type="yesnoType" use="required"/>
       <xs:attribute name="interval" type="xs:string" default="60s"/>
     </xs:complexType>
     <xs:complexType name="leg_eventsubscriptionType">
       <xs:sequence>
         <xs:element name="events">
           <xs:complexType>
             <xs:sequence>
               <xs:element name="keypress"
                 type="keypressSubscriptionType" minOccurs="0"
                   maxOccurs="1"/>
               <xs:element name="signal" type="signalSubscriptionType"
                 minOccurs="0" maxOccurs="unbounded"/>
             </xs:sequence>
           </xs:complexType>
         </xs:element>
       </xs:sequence>
     </xs:complexType>
     <xs:complexType name="keypressSubscriptionType">
       <xs:attribute name="report" use="required">

         <xs:simpleType>
           <xs:restriction base="xs:NMTOKEN">
             <xs:enumeration value="standard"/>
             <xs:enumeration value="long"/>
             <xs:enumeration value="both"/>
             <xs:enumeration value="none"/>
           </xs:restriction>
         </xs:simpleType>
       </xs:attribute>
       <xs:attribute name="maskdigits" type="yesnoType" default="no"/>
     </xs:complexType>
     <xs:complexType name="signalSubscriptionType">
       <xs:attribute name="type" type="xs:NMTOKEN" use="required"/>
       <xs:attribute name="report" type="yesnoType" use="required"/>
     </xs:complexType>
     <!-- Definitions for MSCML event notifications and -->
     <!-- embedded types. -->
     <xs:complexType name="conferenceNotificationType">
       <xs:sequence>
         <xs:element name="activetalkers"
           type="activetalkersNotificationType" minOccurs="0"/>
       </xs:sequence>
       <xs:attribute name="uniqueid" type="xs:string" use="required"/>
       <xs:attribute name="numtalkers" type="xs:string"
         use="required"/>
     </xs:complexType>
     <xs:complexType name="activetalkersNotificationType">
       <xs:sequence minOccurs="0">
         <xs:element name="talker" maxOccurs="unbounded">
           <xs:complexType>
             <xs:attribute name="callid" type="xs:string"
              use="required"/>
           </xs:complexType>
         </xs:element>
       </xs:sequence>
     </xs:complexType>
     <xs:complexType name="keypressNotificationType">
       <xs:sequence>
         <xs:element name="status" type="statusType"/>
       </xs:sequence>
       <xs:attribute name="digit" type="DTMFkeyType" use="required"/>
       <xs:attribute name="length" use="required">
         <xs:simpleType>
           <xs:restriction base="xs:NMTOKEN">
             <xs:enumeration value="standard"/>
             <xs:enumeration value="long"/>
           </xs:restriction>
         </xs:simpleType>

       </xs:attribute>
       <xs:attribute name="method" use="required">
         <xs:simpleType>
           <xs:restriction base="xs:NMTOKEN">
             <xs:enumeration value="standard"/>
             <xs:enumeration value="long"/>
             <xs:enumeration value="double"/>
           </xs:restriction>
         </xs:simpleType>
       </xs:attribute>
       <xs:attribute name="interdigittime" type="xs:string"
         use="required"/>
     </xs:complexType>
     <xs:complexType name="statusType">
       <xs:attribute name="command" use="required">
         <xs:simpleType>
           <xs:restriction base="xs:string">
             <xs:enumeration value="idle"/>
             <xs:enumeration value="play"/>
             <xs:enumeration value="collect"/>
             <xs:enumeration value="record"/>
           </xs:restriction>
         </xs:simpleType>
       </xs:attribute>
       <xs:attribute name="duration" type="xs:string" use="required"/>
     </xs:complexType>
     <xs:complexType name="signalNotificationType">
       <xs:attribute name="type" use="required" fixed="busy"/>
     </xs:complexType>
     <!-- Definitions for miscellaneous embedded, helper data types -->
     <xs:complexType name="promptType">
       <xs:choice maxOccurs="unbounded">
         <xs:element name="audio" type="promptcontentType"/>
         <xs:element name="variable" type="spokenvariableType"/>
       </xs:choice>
       <xs:attribute name="locale" type="xs:string"/>
       <xs:attribute name="baseurl" type="xs:string"/>
       <xs:attribute name="stoponerror" type="yesnoType" default="no"/>
       <xs:attribute name="gain" type="xs:string" default="0"/>
       <xs:attribute name="gaindelta" type="xs:string" default="0"/>
       <xs:attribute name="rate" type="xs:string" default="0"/>
       <xs:attribute name="ratedelta" type="xs:string" default="0"/>
       <xs:attribute name="repeat" type="xs:string" default="1"/>
       <xs:attribute name="duration" type="xs:string"
         default="infinite"/>
       <xs:attribute name="offset" type="xs:string" default="0"/>
       <xs:attribute name="delay" type="xs:string" default="0"/>
     </xs:complexType>

     <xs:complexType name="promptcontentType">
       <xs:attribute name="url" type="xs:string" use="required"/>
       <xs:attribute name="encoding" type="xs:string"/>
       <xs:attribute name="gain" type="xs:string" default="0"/>
       <xs:attribute name="gaindelta" type="xs:string" default="0"/>
       <xs:attribute name="rate" type="xs:string" default="0"/>
       <xs:attribute name="ratedelta" type="xs:string" default="0"/>
     </xs:complexType>
     <xs:complexType name="spokenvariableType">
       <xs:attribute name="type" use="required">
         <xs:simpleType>
           <xs:restriction base="xs:NMTOKEN">
             <xs:enumeration value="dat"/>
             <xs:enumeration value="dig"/>
             <xs:enumeration value="dur"/>
             <xs:enumeration value="mth"/>
             <xs:enumeration value="mny"/>
             <xs:enumeration value="num"/>
             <xs:enumeration value="sil"/>
             <xs:enumeration value="str"/>
             <xs:enumeration value="tme"/>
             <xs:enumeration value="wkd"/>
           </xs:restriction>
         </xs:simpleType>
       </xs:attribute>
       <xs:attribute name="subtype">
         <xs:simpleType>
           <xs:restriction base="xs:NMTOKEN">
             <xs:enumeration value="mdy"/>
             <xs:enumeration value="dmy"/>
             <xs:enumeration value="ymd"/>
             <xs:enumeration value="ndn"/>
             <xs:enumeration value="t12"/>
             <xs:enumeration value="t24"/>
             <xs:enumeration value="USD"/>
             <xs:enumeration value="gen"/>
             <xs:enumeration value="ndn"/>
             <xs:enumeration value="crd"/>
             <xs:enumeration value="ord"/>
           </xs:restriction>
         </xs:simpleType>
       </xs:attribute>
       <xs:attribute name="value" type="xs:string" use="required"/>
     </xs:complexType>
     <xs:simpleType name="yesnoType">
       <xs:restriction base="xs:NMTOKEN">
         <xs:enumeration value="yes"/>
         <xs:enumeration value="no"/>

         <xs:enumeration value="1"/>
         <xs:enumeration value="0"/>
         <xs:enumeration value="true"/>
         <xs:enumeration value="false"/>
       </xs:restriction>
     </xs:simpleType>
     <xs:simpleType name="DTMFkeyType">
       <xs:restriction base="xs:string">
         <xs:pattern value="[0-9]"/>
         <xs:pattern value="[A-D]"/>
         <xs:pattern value="[a-d]"/>
         <xs:pattern value="#"/>
         <xs:pattern value="\*"/>
       </xs:restriction>
     </xs:simpleType>
     <xs:complexType name="gainType">
       <xs:choice>
         <xs:element name="auto" type="autogainType"/>
         <xs:element name="fixed" type="fixedgainType"/>
       </xs:choice>
     </xs:complexType>
     <xs:complexType name="autogainType">
       <xs:attribute name="startlevel" type="xs:string"/>
       <xs:attribute name="targetlevel" type="xs:string"/>
       <xs:attribute name="silencethreshold" type="xs:string"/>
     </xs:complexType>
     <xs:complexType name="fixedgainType">
       <xs:attribute name="level" type="xs:string"/>
     </xs:complexType>
   </xs:schema>

12.  IANA Considerations

12.1.  IANA Registration of MIME Media Type application/
      mediaservercontrol+xml

      MIME media type name: application
      MIME subtype name: mediaservercontrol+xml
      Required parameters: none
      Optional parameters: charset

      charset This parameter has identical semantics to the charset
         parameter of the "application/xml" media type, as specified in
         XML Media Types [8].

   Encoding considerations: See RFC 3023 [8].
   Interoperability considerations: See RFC 2023 [8] and RFC 5022.
   Published specification: RFC 5022

   Applications that use this media type: Multimedia, enhanced
      conferencing and interactive applications.
   Personal and email address for further
      information: eburger@cantata.com [31]
   Intended usage: COMMON

13.  Security Considerations

   Because media flows through a media server in a conference, the media
   server itself MUST protect the integrity, confidentiality, and
   security of the sessions.  It should not be possible for a conference
   participant, on her own behalf, to be able to "tap in" to another
   conference without proper authorization.

   Because conferencing is a high-value application, the media server
   SHOULD implement appropriate security measures.  This includes, but
   is not limited to, access lists for application servers.  That is,
   the media server only allows a select list of application or proxy
   servers to create conferences, to invite participants to sessions,
   etc.  Note that the mechanisms for such security, like private
   networks, shared certificates, MAC white/black lists, are beyond the
   scope of this document.

   Security concerns are one important reason MSCML limits requests with
   conference scope to a separate control leg per conference.  MSCML
   uses the simple, proven, Internet-scale security model of SIP to
   determine if a client is who they say they are (authentication) and
   if they are allowed to create and manipulate a conference.  However,
   the security model to enable a control leg to manipulate arbitrary
   conferences on the media server is extremely difficult.  Not only
   would one need to authenticate and authorize the basic conference
   primitives, but privacy considerations require policies for one
   client to access another client's conferences, even if the two
   clients are on the same host.  For example, if the media server
   allowed any control leg to control any conference, an authorized but
   unrelated client could maliciously attach itself to an existing
   session and record or tap the conversation without the participant's
   knowledge or consent.

   Participants give implicit authorization to their applications by
   virtue of the INVITE to the application.  However, there is no trust,
   explicit or implicit, between the users of one service and a distinct
   client of another service.

   All MSCML messages are sent within an INVITE-created SIP dialog.  As
   a result, it would be difficult for an entity other than the original
   requestor to interfere with an established MSCML session, as this
   would require detailed information on the dialog state.  This allows

   multiple applications to utilize the resources of a single media
   server simultaneously without interfering with one another.

   Because of the sensitive nature of collected data, such as credit
   card numbers or other identifying information, the media server MUST
   support sips: and TLS.  Clients, who presumably know the value of the
   information they collect, as well as the privacy expectations of
   their users, are free to use clear text signaling or encrypted secure
   signaling, depending on the application's needs.  Likewise, the media
   server SHOULD support Secure Realtime Transport Protocol (SRTP) [9].
   Again, the clients are free to negotiate the appropriate level of
   media security.

   The media management facilities of MSCML, such as the <managecontent>
   (Section 8) request, assume a trust relationship between the media
   server and file server.  This scenario is similar to the one
   addressed by URLAUTH [20].  Namely, the media server is acting on
   behalf of a given user, yet the media server does not have
   credentials for that user.  One might be tempted to use the user:pass
   facility of the HTTP URI to offer per-user security, but that also
   requires that the media server be secure, as the media server would
   need to know the user credentials in a form that is easily
   compromised (clear text passwords).

   The IETF is investigating methods for providing per-user or per-
   instance authorization of third-party http writing, as is needed for
   other protocols as well, such as WEBDAV [21].  However, until that
   work is completed, media server implementations MUST be prepared to
   authenticate themselves to file and web servers using appropriate
   authentication means.  At a minimum, the media server MUST support
   HTTPS basic authentication.  Implementers should note that the media
   server will need to respond appropriately to whatever authentication
   mechanism the file server requires.

   As this is an XML markup, all the security considerations of RFC 3023
   [8] apply.

14.  References

14.1.  Normative References

   [1]   Bradner, S., "Key words for use in RFCs to Indicate Requirement
         Levels", BCP 14, RFC 2119, March 1997.

   [2]   Burger, E., Van Dyke, J., and A. Spitzer, "Basic Network Media
         Services with SIP", RFC 4240, December 2005.

   [3]   Donovan, S., "The SIP INFO Method", RFC 2976, October 2000.

   [4]   Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
         Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
         Session Initiation Protocol", RFC 3261, June 2002.

   [5]   "Network call signalling protocol for the delivery of time-
         critical services over cable television networks using cable
         modems", ITU-T J.162, March 2001.

   [6]   Groves, C., Pantaleo, M., Anderson, T., and T. Taylor, "Gateway
         Control Protocol Version 1", RFC 3525, June 2003.

   [7]   Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn, "XML
         Schema Part 1: Structures", W3C REC REC-xmlschema-1-20010502,
         May 2001.

   [8]   Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types",
         RFC 3023, January 2001.

   [9]   Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
         Norrman, "The Secure Real-time Transport Protocol (SRTP)", RFC
         3711, March 2004.

14.2.  Informative References

   [10]  Rosenberg, J., "A Framework for Conferencing with the Session
         Initiation Protocol (SIP)", RFC 4353, February 2006.

   [11]  Carter, J., Danielsen, P., Hunt, A., Ferrans, J., Lucas, B.,
         Porter, B., Rehor, K., Tryphonas, S., McGlashan, S., and D.
         Burnett, "Voice Extensible Markup Language (VoiceXML) Version
         2.0", W3C REC REC-voicexml20-20040316, March 2004.

   [12]  International Packet Communications Consortium, "IPCC Reference
         Architecture V2", June 2002.

   [13]  European Telecommunications Standards Institute, "Digital
         cellular telecommunications system (Phase 2+); Universal Mobile
         Telecommunications System (UMTS); IP Multimedia Subsystem
         (IMS); Stage 2 (3GPP TS 23.228 version 7.2.0 Release 7)",
         December 2005.

   [14]  Hollenbeck, S., Rose, M., and L. Masinter, "Guidelines for the
         Use of Extensible Markup Language (XML) within IETF Protocols",
         BCP 70, RFC 3470, January 2003.

   [15]  Jacobs, I., Lie, H., Bos, B., and C. Lilley, "Cascading Style
         Sheets, level 2 (CSS2) Specification", W3C REC REC-CSS2-
         19980512, May 1998.

   [16]  Rosenberg, J., Schulzrinne, H., and O. Levin, "A Session
         Initiation Protocol (SIP) Event Package for Conference State",
         RFC 4575, August 2006.

   [17]  Cable Television Laboratories, Inc., "Audio Server Protocol",
         January 2005.

   [18]  "Procedures for document facsimile transmission in the general
         switched telephone network", Recommendation T.30, April 1999.

   [19]  "Procedures for real-time Group 3 facsimile communication over
         IP networks", Recommendation T.38, March 2002.

   [20]  Crispin, M., "Internet Message Access Protocol (IMAP) - URLAUTH
         Extension", RFC 4467, May 2006.

   [21]  Dusseault, L., Ed., "HTTP Extensions for Web Distributed
         Authoring and Versioning (WebDAV)", RFC 4918, June 2007.

   [22]  Institute of Electrical and Electronics Engineers, "Information
         Technology - Portable Operating System Interface (POSIX) - Part
         1: Base Definitions, Chapter 9", IEEE Standard 1003.1, June
         2001.

   [23]  Burger, E. and M. Dolly, "A Session Initiation Protocol (SIP)
         Event Package for Key Press Stimulus (KPML)", RFC 4730,
         November 2006.

   [24]  Klensin, J., "Simple Mail Transfer Protocol", RFC 2821, April
         2001.

   [25]  Campbell, B., Ed., Mahy, R., Ed., and C. Jennings, Ed., "The
         Message Session Relay Protocol", Work in Progress, February
         2007.

URIs

   [26]  <http://www.ietf.org/html.charters/sip-charter.html>

   [27]  <http://www.ietf.org/html.charters/sipping-charter.html>

   [28]  <http://www.ietf.org/html.charters/mmusic.html>

   [29]  <http://www.ietf.org/html.charters/xcon-charter.html>

   [30]  <http://www.3gpp.org/ftp/Specs/html-info/23228.htm>

   [31]  <mailto:eburger@cantata.com>

Appendix A.  Regex Grammar Syntax

   The regular expression syntax used in MSCML is a telephony-oriented
   subset of POSIX Extended Regular Expressions (ERE) [22] termed Digit
   REGular EXpression (DRegex).  This syntax was first described in KPML
   [23].

   DRegex includes ordinary characters, special characters, bracket
   expressions, and interval expressions.  These entities are defined in
   the list below.

   . matches digits 0-9, *, #, and A-D (case insensitive)
   *  matches the * character
   #  matches the # character
   [character selector] matches any character in selector
   [range1-range2] matches any character in range from range1 to range2,
      inclusive
   x  matches any digit 0-9
   {m} matches m repetitions of the previous pattern
   {m,} matches m or more repetitions of the previous pattern
   {,n} matches at most n (including zero) repetitions of the previous
      pattern
   {m,n} at least m and at most n repetitions of the previous pattern
   L  the presence of 'L' in any regex expression causes the media
      server to enable "long" digit detection mode.  See Section 7.1 for
      the definition of "long" digits.

   Table 7 illustrates DRegex usage through examples.

       +--------------+--------------------------------------------+
       | Example      | Description                                |
       +--------------+--------------------------------------------+
       | 1            | Matches the digit 1                        |
       | [179]        | Matches 1, 7, or 9                         |
       | [2-9]        | Matches 2, 3, 4, 5, 6, 7, 8, 9             |
       | [02-46-9A-D] | Matches 0, 2, 3, 4, 6, 7, 8, 9, A, B, C, D |
       | x            | Matches 0, 1, 2, 3, 4, 5, 6, 7, 8, 9       |
       | .            | Matches 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B,|
       |              | C, D, #, *                                 |
       | *6[179#]     | Matches *61, *67, *69, or *6#              |
       | x{10}        | Ten digits (0-9)                           |
       | 011x{7,15}   | 011 followed by seven to fifteen digits    |
       | L*           | Long star                                  |
       +--------------+--------------------------------------------+

                         Table 7: DRegex Examples

Appendix B.  Contributors

   Jeff Van Dyke and Andy Spitzer did the concept, development,
   documentation, and execution for MSCML at SnowShore Networks, Inc.,
   which is now part of Cantata Technology, Inc.  Andy Spitzer's
   original work at The Telephone Connection, Inc., influenced the IVR
   implementation.  Mary Ann Leekley implemented the personalized mix
   feature and several other enhancements.

   Cliff Schornak of Commetrex and Jeff Van Dyke developed the facsimile
   service.

   Jai Cauvet, Rolando Herrero, Srinivas Motamarri, and Ashish Patel
   contributed greatly by testing MSCML.

Appendix C.  Acknowledgements

   The following individuals provided valuable assistance in the
   direction, development, or debugging of MSCML:

   o  Brian Badger and Phil Crable from Verizon Business
   o  Stephane Bastien from BroadSoft
   o  Peter Danielsen of Lucent Technologies
   o  Kevin Flemming, formerly of SnowShore Networks, Inc.
   o  Wesley Hicks and Ravindra Kabre, formerly from Sonus Networks
   o  Jon Hinckley from SkyWave/Sestro
   o  Terence Lobo, formerly of SnowShore Networks, Inc.
   o  Kunal Nawale, formerly of SnowShore Networks, Inc.
   o  Edwina Nowicki, formerly of SnowShore Networks, Inc.
   o  Diana Rawlins and Sharadha Vijay, formerly of WorldCom
   o  Gaurav Srivastva and Subhash Verma from BayPackets
   o  Kevin Summers from Sonus Networks
   o  Tim Wong from at&t

   The authors would like to thank Cullen Jennings and Dan Wing from
   Cisco Systems for their helpful review comments.

   The authors would also like to thank Scotty Farber for applying her
   technical writing expertise to the documentation of MSCML.

Authors' Addresses

   Jeff Van Dyke
   Cantata Technology, Inc.
   18 Keewaydin Dr.
   Salem, NH  03079
   USA

   EMail: jvandyke@cantata.com


   Eric Burger (editor)
   BEA Systems, Inc.
   USA

   Email: eburger@standardstrack.com
   URI: http://www.standardstrack.com


   Andy Spitzer
   Bluesocket Inc.
   10 North Avenue
   Burlington, MA  01803
   USA

   EMail: woof@pingtel.com

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