We are using software applications more than ever before. As the demand for new capabilities and functions grows, companies strive to provide an adequate response to business needs. The rate of application evolution places an ever-larger burden on the shoulders of software producers, vendors, and even consumers.

In addition, much of the costly software used by organizations was not designed to respond to a rapidly changing marketplace or highly dispersed workforce, requiring its substitution or modernization.

These challenges and trends have fueled the growth of rich Internet applications (RIA) and software as a service (SaaS), as well as the emergence of new application platforms that are attractive alternatives to traditional on-premise software and systems.

Rich Internet Applications (RIAs) are interactive, desktop-style business applications that are installed at a single location (the server) and are accessible from any portal via the Internet (the client). Depending on the platform, they can take advantage of the local computing power of the client hardware, yet manage all this without the complex installation and maintenance typical of the "Fat Client."

There are considerable advantages when moving to RIAs that include:

• Access via mobile and remote devices
• Desktop-style "drag and drop" functions that offer a much improved user experience compared to Web browser applications
• Software-as-a-Service (SaaS) enablement making applications quickly and easily assimilated by customers of all shapes and sizes who will use your RIA
• Multi-tier architecture that lets businesses better secure the sensitive aspects of their application

On-Demand vs. On-Premise 'Operation'
With the increasing complexity and richness of enterprise applications, a new role has evolved - that of software operators. Applications today are being "operated" even more than they are "produced" or even "consumed." Applications can therefore be classified according to their style of operation:

• On-premise: Traditional mainframe, client/server, based on dedicated resources, in-house infrastructure, and perpetual license-based pricing
• Outsourced: Intranet-based clients and third-party operated and managed infrastructure
• Application Service Providers (ASPs): Web-based clients, cloud infrastructure, subscription based payment
• Software-as-a-Service (SaaS): Where RIAs are based on a multi-tenant, subscription-based pricing model

Enterprises are faced with the question of choosing the most effective and economical mode of software operation, and often are looking at multiple operating modes. Among these, SaaS is probably the "hottest" operating mode, however, that does not mean that its advantage over on-premise applications is completely cut and dry. From the consumer point of view, on-premise means a substantial capital expense whereas on-demand means an operating expense. This makes the decision process in acquiring and paying for the system substantially different.

From an operational point of view, businesses must distinguish between levels of control, where on-premise offers high control and SaaS provides only abstracted control, and the application is simply "consumed." The SaaS model therefore depends on a service-level agreement to ensure that the software is made available according to user demands. In terms of adaptability, on-premise allows for customization - but at a price. With SaaS, where the software is not owned outright, significant customization becomes more difficult.