[QueueNews] Making SIP Make Cents

[QueueNews]

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   Queue E-Mail Newsletter
   for the Week of Mar/26/2007
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Latest Articles:


Making SIP Make Cents
P2P payments using SIP could enable new classes of micropayment
applications and business models.
http://acmqueue.com/rd.php?c.470
   (scroll down to read an excerpt from this article)


Object-Oriented Modeling with UML: A Study of Developers' Perceptions
Developers with prior experience in process-oriented modeling perceived
UML diagrams as easy to use.
http://acmqueue.com/rd.php?c.468



Latest Blog Posts:

Terry Coatta

A New Approach to DB Programming
http://www.acmqueue.com/modules.php?name=News&file=article&sid=377
Object Relational Mappers (ORM) have been around for a while, but I
think they are poised to come into much wider use. While the basic idea
of ORMs is simple - make objects able to automatically persist
themselves to a database - the ramifications on how you program are
fundamental. 

Setting an Example (to program by)
http://www.acmqueue.com/modules.php?name=News&file=article&sid=376
As a parent, I have a strong visceral appreciation for the adage
"actions speak louder than words." It is readily apparent that the
examples I set are far more important than the "words of wisdom" I
occasionally dispense. In this regard, I think a case can be made that
Microsoft is guilty of some very poor parenting.

John Stanik

Happy Birthday, E-Mail
http://www.acmqueue.com/modules.php?name=News&file=article&sid=372
Next week marks a milestone in communication. E-mail that
technological blessing (or curse, depending on how you look at it) is
turning 25. 

The Control Issue
http://www.acmqueue.com/modules.php?name=News&file=article&sid=371
Keeping development costs in control is a recurring problem for many
companies. Software firms that sell their wares for hundreds or
thousands of dollars per user regularly claim that the high price is
needed to cover the cost of development. 


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Solve the Software Production Bottleneck

Software production (the back-end of software development, including
tasks such as build, test, package and deploy) has become a bottleneck
in many development organizations. In this interview Electric Cloud
founder John Ousterhout explains how you can turn software production
from a liability to a competitive advantage.
http://www.acmqueue.com/special/qclg9.php

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New article on ACM Queue:
Making SIP Make Cents
http://acmqueue.com/rd.php?c.470
New micropayment systems might be just around the corner.
by Jason Fischl, Counterpath, and Hannes Tschofenig, Siemens

>From the SIP: Session Initiation Protocol issue, vol. 5, no. 2 - March
2007

article excerpt:
The Session Initiation Protocol (SIP) is used to set up realtime
sessions in IP-based networks.^1 These sessions might be for
audio, video, or IM communications, or they might be used to relay
presence information. SIP service providers are mainly focused on
providing a service that copies that provided by the PSTN (public
switched telephone network) or the PLMN (public land mobile network) to
the Internet-based environment. 

Some advantages of using SIP
for this purpose are: 

  * SIP-compliant elements, including
   hardphones, softphones, PSTN gateways, or proxies can be used on
   the
   network.
  * SIP service providers can easily peer with each
   other at very low cost over existing IP network connections.
  *
   IM and presence service providers are able to federate with each
   other.

 Despite these many benefits, however, SIP systems lack
 an integration with recently introduced identity management solutions
 in
 combination with realtime accounting and payments. This article
 describes how existing SIP deployments address accounting and
 payments.
 It also presents a proposal for P2P (peer-to-peer) realtime accounting
 and payments using SIP in the spirit of federated identity management.

 Challenges

 In a traditional e-commerce environment,
 customers set up direct relationships with merchants. For example, a
 customer creates an account with a merchant (such as Amazon.com) and
 provides credit card and user identification information that can be
 stored for future purchases with the same merchant.

 A typical
 ITSP (Internet telephony service provider) that uses SIP focuses
 mainly
 on the delivery of basic services and the features of a
 telecommunications company, such as voicemail and call waiting. The
 most
 common ITSP model is blended with flat-rate monthly pricing, depending
 on the plan, and per-minute charges for some types of calls. Many
 ITSPs
 are moving to a mostly flat-rate plan where all of the minutes are
 included for an extended geographic region for calls that terminate in
 the PSTN, and all of the calling features are included with the basic
 flat rate. International calls that terminate in the PSTN will still
 have a per-minute charge billed at the end of each month (i.e., a
 postpaid approach).

 Other ITSPs, such as Skype, use a prepaid
 approach. The customer pays a certain amount of money in advance, then
 the ITSP rates individual calls in realtime and debits the appropriate
 amount from the customer's account. To deter fraud, the system
 must be prepared to cut off a call in realtime if the account balance
 reaches zero. A call manager might play announcements offering the
 ability to recharge the account.

 Such a system must also be
 prepared for end users using the same account from different endpoints
 concurrently and must either disallow this behavior or account for it.
 Some network operators want to prevent users from directly
 communicating
 with each other without involvement of the operator via SIP signaling.
 This requires additional protocol interaction between SIP entities and
 routers at the border of the network administrator's domain.

 [fischl1.jpg] width="488" height="347">

 As shown in figure 1, the following
 are the components of a traditional SIP-based ITSP accounting
 management
 system (we use terminology from RFC 2975^2 as much as
 possible):
  * SIP server. This server
   offers access to the credential database for user authentication,
   potentially using protocol extensions such as Diameter SIP
   Application
   (RFC 4740^3) or RADIUS Extension for Digest Authentication
   (RFC 4590^4).
  * Call routing engine
   (typically a SIP proxy). This entity decides how to route the
   call based on the dialed address or number.
  * SBC
   (session border controller, typically a SIP signaling element and
   a
   media relay). This network entity acts as a controller between
   the ITSP's network and the PSTN gateway. It may also communicate
   with the RADIUS server to authorize the caller and to account for
   each
   call. This element is also responsible for terminating the call in
   realtime when there are insufficient funds. This entity plays the
   role
   of a RADIUS or Diameter client for (realtime) accounting.
  *
   RADIUS or Diameter Client/Server. A RADIUS (remote
   authentication dial-in user service) or Diameter server is
   responsible
   for receiving user connection requests, authenticating and
   authorizing
   the user, and then returning all configuration and authorization
   information necessary for the client to deliver service to the
   user. The
   RADIUS or Diameter server in turn communicates with the billing
   and
   payment system. The role of a RADIUS or Diameter client may be
   played by
   an SBC, a SIP proxy, or a SIP server. The RADIUS or Diameter
   client
   transmits accounting records at the beginning, during, and at the
   end of
   the call. Protocols such as Diameter Credit Control^5 and
   RADIUS Prepaid Extensions^6 may be used to provide realtime
   accounting capabilities. Non-realtime accounting is offered via
   the
   Diameter Base Protocol (RFC 3588^7) and RADIUS Accounting (RFC
   2866^8).
  * Billing server. This
   entity is responsible for the act of preparing an invoice.
  *
   Payment server. This entity is responsible for all
   e-commerce transactions, such as credit card transactions to add
   funds
   to a prepaid account or to process the monthly fee in a prepaid
   system.
   The term payment refers to the transfer of monetary amounts
   resulting
   from the accounting process.

 Read the rest of this article at acmqueue.com
 http://acmqueue.com/rd.php?c.470
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