IBM i Gets SaaSy

Why the platform is the perfect software as a service platform


Editor’s Note: This article is a summary of the IBM whitepaper, “IBM i and SaaS: Positioning IBM i as a software as a service platform.”

IBM i is undeniably one of the best multiworkload, multiuser business platforms available. With hundreds of thousands of systems worldwide, this midsize computing powerhouse is a highly available, dependable, run-the-business system, whose architecture is designed to deliver applications in a hosted manner running software-as-a-service (SaaS) applications. Let’s review the capabilities that make IBM i well suited for SaaS and highlight some key solution providers who use IBM i in a hosted environment (see the “Who’s Doing It?” sidebar).

IBM i and SaaS

IBM i offers authorization and authentication services, integration, performance, management and monitoring tools, pricing and deployment options to make it well suited to a hosting environment. Figure 1 illustrates different models of SaaS/hosting as it pertains to IBM i. Moving from model I on the left to model V on the right, you see a transition from expenditures for hardware and software to expenditures based on transactions or monthly charges for the service, or both.

Before we go further, let me provide some definitions for the blocks we see on the chart in Figure 1 as they relate to IBM i. The layer above the data-center floor layer is the infrastructure layer. This includes the hardware resources and management/monitoring functions required to host the software application. The products for IBM i that provide these capabilities are IBM PowerVM, IBM PowerHA, Virtual I/O Server (VIOS) and LPAR functions, and the evolving IBM Systems Director and IBM Tivoli capabilities that allow for provisioning and creating OS images and partitions as well as monitoring image and OS health and status. The next block is the OS itself that provides job scheduling and processor management, memory management and multiuser capabilities. IBM i provides the work-management infrastructures that include subsystems, memory pools, job/process/thread management, system directory and validation lists for user and group security, and independent auxiliary storage pools. All of these can be used to provide containers and isolation capabilities for SaaS applications. The next layer is the Data Platform (DP) layer. This is the domain of DB2 for IBM i and provides the relational database support and access for applications. Above the DP layer is the Application Platform (AP) layer, the runtime containers where an application is deployed and run, providing application isolation and runtime services. Java 2 Enterprise Edition (J2EE) application servers such as WebSphere and Web Logic or .NET application servers can be viewed as application platforms. On IBM i, this can be the IBM WebSphere J2EE server, but it can also be subsystems running IBM i programs and jobs written in RPG using IBM i work-management capabilities, or the Apache HTTP Web container running CGI or PHP Web applications. The topmost layer is the SaaS business application itself.

The physical or isolated multitenancy model is an option for SaaS and hosting but it’s not “multitenancy” in that any new customer or tenant is serviced by a completely new hardware footprint that will run the application totally isolated from any other tenants running on separate hardware and OS stacks.


Jon Rush is a technical consultant in IBM STG Lab Services and helps ISVs work with IBM technologies to provide IBM i solutions.

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