SIP vs. API How Will You Be Developing Your Next Application? (SIP-01)

SIP vs. APIHow Will You Be Developing Your Next

Application?(SIP-01)

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Competing methods

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Drivers

Hardware

NETANN

Development Building Blocks

Your Application

Compiled XML Graphical

C/C++ Java VoiceXML

API

SIP

MSCML MSML/MOML

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API – What is it?

If all else fails, refer to Wikipedia:

APIAn application programming interface (API) is a

source code interface that a computer system or program library provides to support requests for services to be made of it by a computer program.

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Legacy API Architecture

Application

API

Device Driver

T1 InterfaceHardware

API

Device Driver

ResourceHardware

PSTN

H.100

Proprietary

Proprietary

Proprietary

Proprietary

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API Development

Key Attributes:• Powerful• Feature Rich• Highly Efficient• Highly Complex• Slow to Develop• Hard to Debug• Proprietary (mostly)

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Drivers

Hardware

NETANN

Development Building Blocks

Your Application

Compiled XML Graphical

C/C++ Java VoiceXML

API

SIP

MSCML MSML/MOML

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SIP – What is it?

Wikipedia:

SIPThe Session Initiation Protocol (SIP) is an application-layer

control (signalling) protocol for creating, modifying, and terminating sessions with one or more participants. These sessions include Internet telephone calls, multimedia distribution, and multimedia conferences. (cit. RFC 3261).

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SIP – Where does it fit?

RTP SIPHTTPSMTPL5

TCP UDP

IP

Ethernet PPP

Copper Fiber Wireless

L4

L3

L2

L1

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SIP Development

Key Attributes:• Open• Standard• Interoperable• Easy to Debug• Inefficient• Moving Target• Slow to evolve

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SIP Architecture

Service CreationEnvironment

SIP Protocol Stack

MediaGatewayResource

MediaResource

LAN

SIP

PSTN

Application

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Two Classes of Resources

• Media Gateways– Provide connectivity to existing TDM infrastructure– 90% + of installed base is still TDM

• Media Resources– IVR – Play / Record / DTMF– Conferencing– Fax– Tone Detection/Generation– Announcements– Transcoding

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Speeds Development Time

PCI

SIP

IntegrationTime inMan-Years

1

2

3 Customer A:Just over 3 Man-years to integrate and test with a Legacy PCI

BladeSame customer using SIP based hardware,

88% less time to market!

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Drivers

Hardware

NETANN

Development Building Blocks

Your Application

Compiled XML Graphical

C/C++ Java VoiceXML

API

SIP

MSCML MSML/MOML

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NetAnn – What is it?

NetAnn• RFC 4240 as of December of 2005 • Predecessor to MSCML. • Basic announcements• Simpler conference model (no control dialog)• Doesn’t provide for mid-call requests and responses.

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MSCML – What is it?

MSCML – Media Server Control Markup Language• RFC 4722 in November 2006• Provides “services” to users at an application level• Services specified in user part of URI.

• For example – “Conf” service implies a star connection topology with a mixer at the center, or PlayCollect connects a “player” and a “dtmf-receiver” to the call

• Conf, IVR (Play, PlayCollect, PlayRecord, FaxPlay, FaxRecord)

• Command oriented protocol (vs scripted)• MSCML IVR syntax is modeled on the H.248 and

MGCP• Includes the composite PlayCollect and PlayRecord

functions

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MSCML - Sample

Example of a Play command:

<?xml version="1.0" encoding="utf-8"?><MediaServerControl version="1.0"><request><play id="234"><prompt><audio url="http://10.3.0.2/hello.wav"/>

<variable type="date" subtype="ymd" value="19760102"/>

<variable type="silence" value="5"/>

<variable type="duration" value="2"/></prompt></play></request></MediaServerControl>

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MSCML Conferencing – Create

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MSCML Conferencing – Play

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MSML / MOML – What is it?

MSML – Media Sessions Markup Language•Device Control Protocol that focuses on internal media server resources

• SIP is normally concerned with the behavior external to the media server

•Provides a mechanism for invoking MOML or VXML scripts.•Provides a mechanism for creating conferences and modifying their topologies.•Does not provide for IVR control

MOML – Media Objects Markup Language•MOML is a scripting languages that provides a defined set of useful IVR primitives: play, generate dtmf, recognize dtmf, record, recognize speech, and others•Primitives can be combined into groups, and multiple groups can be established concurrently. Lots of flexibility at the cost of complexity•It is a scripting language with an internal state machine, but only 2 primitives have state, and they only have 2 states (stop/go).

• Absence of flow control limits scripts to functions rather than applications (eg VXML)

IETF Draft (no RFC)

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MSCML vs MSML/MOML

Application Level Services vs Device Control• MSML provides explicit internal connection topology.• MSCML provides predefined services with implicit internal connection

topologies• Provides a less complex interface for 99% of what’s required.

Scripting• MOML provides a script execution capability to build composite functions.

• State Machines within primitives are so limited as to be of little general use.• Requires a script execution framework.

• MSCML provides defined composite functions• For example PlayCollect/Record provide integration between the Play and the

Collect/Record functions. Much simpler for 99+% of use cases• No script engine required: provides performance advantages as well as

simplicity

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Who supports what?

MSCML / NetAnn MSML / MOML

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Media Control -Bottom Line

• Neither MSCML nor MSML/MOML are likely to be the “Final Answer”.– Both rely on INFO messages which the IETF SIP arbiters do not like

• Both will allow you to do what you need to get done• MSCML is our favorite:

– Greater standards “coverage” (RFC vs not RFC)

– Easier to use (Operates at application level vs device control)

– More widely adopted

– Better adapted to 3GPP MRF (IVR mapping to H.248 used in MRFC-to-MRFP)

• Discussion is carried out in the “mediactrl” - Media Control BOF Discussion List – “Final Answer” likely 2 to 3 years out.

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Will we need APIs and SIP?

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How do they compare

Capability / Feature API SIP+NetAnn SIP+MSCML

TDM Bus Switching (H.100)

Yes No No

Industry Standard (RFC?)

No Yes Yes

Basic IVR Yes Yes Yes

Complex IVR Yes No Yes

Mixing/Recording Yes No No

Simple Conference Yes Yes Yes

Complex Conference Controls

Yes No Yes

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The Future

• Expect many new applications to leverage SIP– With one of the media server control protocols

• APIs will continue, but only for very complex apps.– Secret: our SIP and MSCML uses our API under the covers!

• Expect continued refinement – of SIP and related media server protocols

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Questions?

?

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Booth #115

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