The Application Network
Application Network is a new term that reflects the reality that networks need to be closely integrated with applications to insure that the enterprise effectively bridges the gap between infrastructure, devices, applications and users. This converged network, the application network, is seen as the source of a new generation of solutions - and at the core is XML.
To trace the evolution of application network, we can look back to XML's emergence around 1995 as a meta-language for defining domain specific vocabularies. Soon after XML's arrival, XML-RPC was launched as a way to eliminate the infrastructure constraints imposed by code centric distributed computing approaches such as CORBA and DCOM. Around 2001, XML's success in enabling data distribution across networks led to the rise of web services, centered around a host of XML technologies that included SOAP envelopes and protocols for platform-independent distributed computing, WSDL for describing web services and UDDI for publishing and lookup. With the web services infrastructure in place, we then began to see architectural solutions structured around distributed XML interactions and leading to what has become known as SOA or service oriented architectures.
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Figure 1. Conventional vs. Service Oriented Architecture (SOA)
As illustrated in Figure 1, SOA represents a major change in the structure of web based applications. Conventional web-based client server applications are organized in tiers – a web tier to manage browser interaction, an application tier to hold the business logic and a data tier for data management. In the new world of SOA, application functionality is distributed across a variety of platforms delivering data and services based on XML messaging. These XML messages, typically traveling in XML SOAP envelopes with services defined by XML-based WSDL descriptors.
With service-oriented architectures delivering pieces of an application from across the network, new applications are emerging that integrate content from different network locations into a central portal. For application builders this means that the application and the network are now more closely tied to each other. Developers must understand how their technology impacts the network and network planners must more closely understand their applications and how they affect network performance. One of mantras heard over and over at Interop was that responsive, available, accessible applications delivered efficiently to end users are the only measures by which IT should be judged.