12.1
INTRODUCTION – THE MOVE TO HOSTED
SERVICES
It all started with Internet Service Providers (ISPs) offering to host a company’s website and email. ISPs can offer economies of scale and could cost effectively maintain a permanent connection to the Internet and offer dial-up solutions to their customers. The customers in return get a permanent presence on the Internet for their website and permanent email delivery service.
In the corporate environments the move from centralised server and mainframe environments to peer-to-peer networks with local workgroup servers had started the return to centrally managed servers. In the early to mid-1990s, technologies such as the Citrix WinFrameeproducts enabled
resurgence in the centralised management and delivery of enterprise applications.
These two technology solutions combined with organisational desires to outsource functions of business activity, seen to be non-core, led to the opportunity for application hosting services. The idea of thin client computing was born and the web browser became the ultimate thin client application. Architectures such as the now famous three-tier architecture of client, web server and back office database engine spawned the use of server side scripting and Java applications running either on the web server or in the web browser (applets in this case) and then-tier architec- ture model was born. This model has given birth to application servers and the architecture of call servers and softswitches.
This evolution of technology has enabled the growth in the service provider marketplace (xSPs as they have become known) including:
† ISP – Internet service provider.
Next Generation Network Services Neill Wilkinson Copyrightq2002 John Wiley & Sons, Ltd ISBNs: 0-471-48667-1 (Hardback); 0-470-84603-8 (Electronic)
† ASP – Application Service Provider.
† WASP – Wireless Application Service Provider.
† WISP – Wireless ISP.
† AIP – Application Infrastructure Provider.
† ITSP – Internet Telephony Service Provider.
† CSP – Content Service Provider.
† Telecom hotels – where web, email and telephony services are provided with a building as part of the fabric like other utilities such as water and electricity. These hosting centres are sometimes shared, for example in the UK, London Docklands is host to Tele- house, a building providing shared services for a number of ISPs with international interconnections to other Internet hosting centres and tier 1 ISPs (those ISPs with a direct connection to the main Inter- net backbone or those ISPs who actually own some of the main Inter- net backbone that other ISPs buy capacity on).
The forecasts for the growth and development of this market area were extremely bullish in 2000 with all the major research organisations fore- casting huge potential revenues from this market opportunity. Whilst the figures may well be exaggerated the use of these kinds of services will increase as confidence in both the technology and the ability of the SPs to deliver on quality and security increases and of course the ability to bill for the usage of such services. The model itself will continue to provide a valuable architectural concept for the delivery of next-generation network services, as it encompasses the desire for the mixture of processing power both in the network and in intelligent devices.
All xSPs share the same characteristics, those of: offering services over a network connection, managing the services on behalf of the customer, providing the same service to many customers to gain economies of scale and generally levy a recurring fee (monthly, quarterly or annually). The concept on a rental-based service delivery is not new and facility management companies have been providing similar services for some time. The newness is in the delivery mechanism – over a network. Tele- communication service providers have been providing this service for some time and in some countries the telephone line and handset were rented from the telecoms operator. This arguably puts telecoms operators in a strong position as their internal processes and business systems are set up to manage a rental approach to service delivery.
The key message from the previous paragraph is that the telecommu- nications network operators who have decided to move their infrastruc- tures to deliver next-generation network services are moving to a very strong position in the marketplace. Not only will they be able to offer more services such as application hosting (ASP), but they will be able to offer infrastructure provision in the form of virtual private networks and dedi- cated servers in hosting centres. This means telecommunication network
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operators moving in this direction stand to have the capability to offer the service providers services. In Chapter 14 the idea of a virtual service provider is explored and other concepts of how the market may develop. This very brief description outlines the change from the basic web server, to a new application server and content delivery framework. This framework will sit alongside and even underpin the call server frameworks to enable the combination and collaboration of telephony services and enterprise applications in a network-based hosted environ- ment. Three components will form the basis of all new services, two of which we have explored: softswitches and application servers. The third component is infrastructure. Session Initiation Protocol (SIP), Extensible Markup Language (XML) and Java will be the dominant technologies that will bond this new service orientated environment together.
12.2
PRESENCE
In Chapter 11 call centre services were explored and their evolution to presence centres was postulated. The following section explores the concept of presence, and by the end the reader should be able to under- stand how presence as a concept and a service could underpin many services clambering for the throne of the elusive ‘killer application’.
One of the most compelling services to come from the Internet recently has been Instant Messaging (IM). All the major portals and ISPs (MSN, Yahoo, AOL/Compuserve, LineOne, etc.) offer an IM service and client application. The early releases of IM clients were incompatible in a bid to create tie-in to a particular portal (not unlike the browser wars that ruled the ’net a little while back), however, more recently a number of clients have started to appear that are compatible with the others.
The Internet Engineering Task Force (IETF) have got involved and at the time of writing two informational RFCs have been written and three Internet drafts under the Instant Messaging and Presence Protocol Work- ing Group (IMPP-WG). The working group’s aim is to define protocols and data formats for the IM and presence community, to allow robust Internet-scale IM and presence applications to be constructed. All was not easy with the IETF during the formation of this group and a number of different parties all proposed different approaches to IM and presence solutions, this finally resolved, work is still underway to complete the standardisation effort.
The informational RFC 2778 describes presence and IM systems as systems that allow users to subscribe to changes in each other’s state and for users to be able to send each other instant messages. In the case of current IM applications this state is normally represented as some form of ‘buddy list’ and instant messages can be sent to and from both web clients and Short Message Service (SMS) or Wireless Application Protocol
(WAP) interfaces. IM clients also currently integrate access to email and an online diary/calendar.
So what is the difference between IM and presence? Current IM appli- cations only really reflect whether you are online or offline. Presence services will reflect more dynamic behaviour linked to location-based services and with information about the type of terminal you are using, the type of communications you are capable of receiving.
This means the integration of technologies such as: voice over IP, IM, mobile handsets and Personal Digital Assistants (PDAs), Public Switched Telephone Network (PSTN) services, email and perhaps even online games. One of the early examples of this kind of presence client is from Hotsip, their Active Addressbookeclient. It allows you to instigate multi-
player network games whilst communicating with friends either via text- based chat session or voice/video over IP. It is designed around the SIP protocol.
What are the key components to a presence service? Figure 12.1 shows the key components of a presence service (this is based on RFC 2778).
The presentity software is responsible for informing the presence
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service of the changes in the status of the user, called the ‘presentity’. In the case of a user application as shown in the figure this is reflecting the changes the user instigates by selecting status changes in their Graphical User Interface (GUI). However, in an embedded application say in a mobile device, this could reflect location updates, availability of different communications medium (say I just walked into a room that has a wire- less Local Area Network (LAN) or a Bluetooth LAN) or user changes.
The watcher software is responsible for receiving updates about ‘buddies’ and for instigating the subscription to the buddy’s information with the presence service. The watcher can also do one-shot updates by polling the presence service for an update. The watcher software is known as either a ‘subscriber’ or a ‘fetcher’ for each of the operations outlined in the previous sentence.
Clearly for this model to work and information to get exchanged between presentities and presence services, a protocol and the structure of the messages to be exchanged must be defined. These topics are still items for discussion in the IETF-WG, but SIP is one of the strong proposals for the protocol and a draft proposal has been made available for the message formats for IM and presence (draft-ietf-impp-cpim-nsgfmt- 03.txt).
We started with a bold statement on presence, that it will be a key service enabler in the future next-generation network. Maybe after the previous description readers can form their own view as to the future of presence?