B2B Integration : A Practical Guide to Collaborative E-commerce

Enterprise Application Integration (EAI) 105
Application A Application B
Figure 4.5. — Business process integration
4.6. Types of Enterprise Systems
To understand EAI, one must first understand the types of application
frameworks and architectures which exist with an organization. EAI can
involve legacy systems, ERP packages, CRM systems, SCM systems
and other applications.
4.6.1. Legacy systems
The term 'legacy system' typically refers to large mainframe, minicomputer
and UNIX systems that use terminal-based (thin) clients.
These systems are comprised of mission-critical business applications,
databases and file management capabilities, typically contained within
one central operating environment. There are estimates that upwards of
70% of corporate data still reside on legacy systems.
Today it seems that those who profit from EAI have their own
definitions of what a legacy system is. Some have expanded the term
'legacy system' to refer to any existing application that uses languages,
platforms, or techniques that are older than the current technology.
Contrary to popular belief, legacy systems still provide the majority
of the back-office processing capability for most Fortune 500 companies.
These systems can typically support a very large user base and provide
processing power still unmatched by any distributed system. Advances