www.3tera.com Software-as-a-Service (SaaS) is among the fastest growing segments of the technology industry. Although much of the attention focuses on the low entry cost for users and subscription revenue stream for providers, the viability of SaaS really stems from the fact users simply prefer SaaS applications. Operating the application themselves, allows SaaS providers to focus on the user experience rather than on the IT team who installs and maintains the application. Salesforce.com and Webex have proven SaaS is a viable business model and inspired a wave of change in the software industry. However, typical ISVs face a significant challenge in adopting the SaaS model; architecting multi-tenant applications.
Multi-tenant applications, like Salesforce.com, are shared among all customers. When all users share a common database, such as a search engine, sharing the application offers few challenges to the developer. On the other hand, sharing applications in which users access only their own data, such as CRM, requires securing data from inappropriate use. The added security wouldn't be needed if each user had their own dedicated application and database. Unfortunately, hosting individual applications for each customer hasn't been feasible due to the economics of IT operations. The manpower involved in deploying and maintaining hundreds of copies of a complex application would make the cost of the resulting service unappealing to users. Therefore, to reduce operating costs the provider must share a single application among all users.
Building a multi-tenant application has its own costs. Architecting systems for multi-tenancy requires scarce skills. Additional engineers are required and development and test cycles are longer. In addition, when all subscribers share the same application, upgrades and outages affect the entire user base, creating spikes in support needs. Therefore, designing for multi-tenancy is a tradeoff; increasing engineering expense and time-to-market in order to lower the cost of service.
AppLogic changes the economic assumptions that drive the need for multi-tenancy by eliminating most of manpower required in typical IT operations. Instead of provisioning servers and installing software, AppLogic applications are built with virtual appliances, essentially disposable infrastructure that becomes part of the application. When an application runs, the infrastructure required is created dynamically, maintained while the copy runs, and then disposed of when it stops. This allows operators to maintain a simple grid of commodity servers, and not the complex infrastructure used by the applications. AppLogic enables copying and deploying complete applications for subscribers without operator intervention. The provider can automate the entire process starting with the user's click on a browser to subscribe and ending with the user logged into a private copy of the application.
Enabling SaaS providers to deploy individual copies of applications for their subscribers eliminates the need for multi-tenancy in most applications. Therefore applications can be brought to market quicker with smaller staffs.