SIP-based Media Server Controlling
Protocols
Ilkka Kiiskinen
22.04.2008
Supervisor: Prof. Joerg Ott
Instructor: M.Sc. Kari Haapala
Table Of Contents
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Background for the evaluative research
– Background
– Research tools
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Terminology and environment
– Terminology & Environment
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Underlying protocols
Media server control protocols
– Media Server Control Markup Language and Protocol (MSCML)
– Media Server Markup Language (MSML)
– Media Server Control Protocols (MSCP)
•
Analysis and evaluation
– High level protocol analysis and evaluation
– Protocol analysis for purposes of a company
– Alternative solutions
•
Conclusion
Background for the evaluative
research - what is this about?
Background
• Real-time multimedia applications require media processing, such as
audio and video rendering, conference services and interactive voice
response services. Current intelligent endpoint terminals can execute
media processing but in some cases centralized media processing
provide more efficiency.
• The devices that execute centralized media processing are called
media servers. The efficiency of the media servers has boosted the
demand and the interest of the media servers gaining common market
acceptance to them.
• Media servers’ media processing resources are available to external
servers via different kind of control channels. Currently there are none
single standardized protocols for media server control but many
similar protocols compete on the same field. This consumes
development resources both from protocol development and service
applications development.
7/24/2016
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Background and research tools
• This thesis studies SIP- (Session Initiation Protocol) and XML-based
(eXtensible Markup Language) media server control protocols on market
year 2007.
• The examined protocols - Media Server Control Markup Language
(MSCML), Media Server Markup Language (MSML) and Media Server
Control Protocol (MSCP) - are evaluated both on common level and from
Tecnomen Corporation perspective.
• Additionally some research work and evaluation of existing alternative
media server control solutions have been done.
• The thesis represents the strengths and weaknesses of each protocol,
and it proposes the best suitable protocol standard candidate on common
level and for a specific company’s purposes.
Terminology and environment
IMS
3G Cell phone
Terminal
PSTN
Access
Network
SS7/ISDN
TDM
SIP/H.323
RTP/RTCP
CIRCUITSWITCHED
NETWORK
(PSTN)
Gateway
Other IMS
Elements
Gateway
IP-Network
SIP
RTP/RTCP
Connection Control
+ Signaling
SIP/H.323
Media Streaming + Signaling
SIP/H.323
RTP/RTCP
Media Streaming
RTP/RTCP
Connection control
+ Media Control
SIP/Media Server Control Protocol
Application Server
Media Service
Network
Architecture
SIP/H.323
RTP/RTCP
SIP/H.323
RTP/RTCP
Switch
Media Server
SIP/H.323
RTP/RTCP
Laptop
Storage Access + Media
HTTP/FTP/NFS
Tablet Computer
PACKET-SWITCHED
NETWORK
(IP-NETWORK)
PC
Media Database
•Media
•Media Session
•Terminals
•Media Server
•Application
Server
•Media Database
•Gateway
•Media Control
Underlying Protocols
Underlying Protocols
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SIP
– An example about SIP message (SIP INFO) with some
common headers and MSCML payload:
INFO sip:ilkka@172.17.2.33 SIP/2.0
Via: SIP/2.0/UDP 172.80.2.100:5060
From: Ivr <sip:ivr@172.80.2.100>;tag=43
To: Ilkka <sip:ilkka@172.17.2.33>;tag=9753.0207
Call-ID: 984072_15401962@172.80.2.100
CSeq: 25635 INFO
Content-Type: application/mediaservercontrol+xml
Content-Length: 287
<MediaServerControl version="1.0">
<response id="332985001" request="playcollect" code="200"
text="OK" playduration="5200ms" playoffset="5200ms"
digits="2543"/>
</MediaServerControl>
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RFC4240, “Basic Network Media Services with SIP”.(Netann; Network
Announcement)
VXML & CCXML
Media Server Control Protocols
Media Server Control Protocols
• To extend RFC4020 for advanced IVR and
advanced conferencing
• Media Server Control Markup Language and
Protocol (MSCML)
• Media Server Markup Language (MSML)
• Media Server Control Protocol (MSCP)
Media Server Control Markup Language
and Protocol (MSCML)
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Media Server Control Markup Language (MSCML) [RFC5022] is made to fill
the needs that Netann misses.
Not a self standing specification. It is always used in conjunction with Netann.
Netann carries the basic SIP-network media services: basic conferencing
service, announcement service and prompt and collect service. MSCML
carries out the others.
MSCML reached RFC status on November 2006, RFC4722. RFC4722 has
been obsolete by RFC5022 since September 2007. [RFC5022]
Two broad classes of MSCML functionality: advanced conferencing and IVR.
There is also a small subset of fax processing features which can be seen as
the third, scarce, class of functionality.
MSCML carries out IVR and advanced conference requests and responses
(only) over SIP, and VXML carries out HTTP interface for IVR requests and
responses.
Media Server Control Markup Language
and Protocol (MSCML)
• MSCML uses combined, fixed operands to execute the most common
operations
• Poor flexibility and extensibility
• Only one request, response or notification allowed per message
• Uses Call Control Leg for conference management (dedicated SIP
session)
• The most mature (in protocol status)
• Good market acceptance
Media Server Markup Language
(MSML)
• Like MSCML, MSML has capabilities to serve IVR and enhanced
conference services.
• MSML complements RFC4240 (Netann)
• Current draft for MSML is built from two separate internet drafts,
Media Sessions Markup Language and Media Objects Markup
Language (MSML/MOML).
• MSML can be used for interactive dialogs, but it also can be used to
invoke other IVR languages, such as VXML.
• MSML has an object oriented perspective for the media server system
architecture.
– The three classes of media objects defined by MSML: network
connection, conference and dialog
Media Server Markup Language
(MSML)
MSML Core
• Payload transaction with SIP or
preferebly with dedicated
transport channel (such as TCP)
• MSML defines a concept
“package” for language structure.
“A package is an integrated set of
one or more XML schemas that
define additional features and
functions via new or extended
use of elements and attributes.”
Defined rules to create a new,
extensive package.
Dialog Base
Core
Audit Core
Dialog Base
Audit Dialog
Dialog Transform
Audit Conference
Dialog Speech
Audit Connection
Dialog Group
Audit Stream
Dialog Fax Detect
Dialog Fax Send/
Receive
Conference Core
Media Server Markup Language
(MSML)
• Scripted language
– Flexible and easy to extend (packages)
– A bit complex just for most common and simple operations
• The most extensive feature set
• The modular basis for protocol enables also modular implementation
development, and lets every implementer to decide themselves what
to develop and what is important to them.
• MSML has defined support for multiple request, response or
notification elements in a single control message.
• Fairly good market acceptance
• During the work of this document The Internet Engineering Steering
Group (IESG) has given to the MSML document status “Dead”
(24.9.2007), and IETF has focused the work to the MEDIACTRL.
Media Server Control Protocol
(MSCP)
•
•
•
•
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The third and the latest developed of these SIP-based proposals for media
server control interface protocol at hand.
MSCP is (was) IETF’s internet-draft for an application server to control
interactive media and conferencing functions on media server and
notifications related to these functions.
– MSCP has been already removed from IETF Internet-Draft database
since it has expired the maximum lifetime of unrevised documents.
The protocol messages are modeled on W3C (World Wide Web Consortium)
CCXML 1.0 elements for interactive dialog and conferencing.
MSCP can rely working with SIP messages, but the description encourages
using dedicated channel for message transportation.
Leans to VXML+CCXML
3GPP had MSCP on their candidate lists
Flexible design
Incomplete protocol description
Overrun by MediaCtrl’s Media Server Control Protocol
Analysis and evaluation
Analysis and evaluation
• High level analysis
• Protocol analysis for a specific company’s
purposes
• Alternative solutions
High level analysis
• The criterions (evaluative questions) for every graduation keys were
created:
• Capabilities: How many different kinds of functions the protocol
supports (existing, mentioned in the protocol description, conjunctive
protocols or tools are taken into account)? How the functions meet the
needs? Architectural design: How solid and practical is the structure of
the architecture? How complex is the architectural design?
• Protocol status: What is the status of the protocol?
• Progress (in development): Is protocol development in active progress
or is it stagnant?
• Extensibility: Can the protocol be extended with vendor specific
functions?
• Flexibility: Is the protocol flexible? Can the protocol be modified if
needed?
High level analysis
• Implementation drive: Who are driving the protocol? Are there big
players as background for the protocol? Commercial implementations
and markets: Are there commercial (successful) implementations?
(Do these implementations give first comer’s advantage?) What are
the current/future estimations for market shares? Are there any trends
on view?
• Position in IMS: Does the protocol have any role in IMS? (can be seen
as market potential)
• Intellectual Property statements: Are there any restrictions from IPR?
• Capacity bottlenecks: Are there any capacity limitations in the protocol
itself?
• Security: Have attention been paid to the security features?
High level analysis
Results (suggestive)
Protocol analysis from a
specific company’s purposes
The specific criterions and explanations for every graduation keys are:
• Strategic Fit: Does the protocol fit to the company strategy and roadmap?
• Market potential: Does some protocol provide a higher market potential than
others and why?
• Channel Partner Requirements: How well the protocol suits for channel
partner deals? Can it be sold to partners as a solution for Media Server
Control interface? (partners’ opinion)
• Former tendency and current resources: Are there ready (partial) solutions?
Does the former tendency support the development of the protocol? Is there
know-how and resources available? When is the expected time-to-market?
• Continuity: Does the protocol complement current product? How well it suits
in existing product?
Alternative solutions
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Megaco/H.248
MRCPv2
VXML+CCXML
MediaCtrl Working Group
Conclusion
Conclusion
• MSCML, MSML & MSCP: MSML and MSCP have more or less dried
out, the future for those does not seem to be very promising. MSCML
has gained some foothold in the markets, but it seems not be a farreaching solution. There may never be one standard that is
universally accepted to control all media servers, however, a clear
trend is emerging — the use of the web model based on an XML
language and the use of SIP for session establishment.
• VXML & CCXML: VXML complemented with CCXML is the emerging
call control and media server control interface. CCXML is becoming a
defacto standard to be supported by media servers.
• MediaCtrl Protocol: upcoming strong candidate as universal standard
Possible future work
• The work of this study could be continued by making a
market study about the IMS’ MRF current market shares,
market forecasts and estimates.
• Also the implementation of a media server control protocol
can be seen as a potential assignment and challenge.
• This study has also only an overview about CCXML.
Since the interest of the markets towards CCXML has
been raised a lot, it could be studied in more detailed.
• The progress and gained results of the MediaCtrl Working
Group could also be evaluated and studied.
Thank you!
Questions?