Cloud computing has evolved into serverless computing, an application architecture that includes more client-side code, a reliance on managed services, and the removal of direct server interaction. The serverless architecture can reduce operational costs and increase developer productivity, shared Randy Frerking, distinguished systems engineer for z/OS Enterprise and Cloud Services at Walmart, during his SHARE Virtual 2020 Best of the Best session, "Serverless Computing: A Walmart Perspective." The session was presented along with Rich Jackson, principal systems engineer at Walmart.

Frerking said, "Serverless computing is the next evolution of the cloud delivery model and has implicit high availability." It enables the building and running of applications that do not involve server management, and it is a deployment model where applications are loaded onto a platform at the exact moment of demand. Moreover, he adds, it supports Backend as a Service (BaaS) and Function as a Service (FaaS).

Walmart's serverless computing environment, self-service provisioning portal, and z/OS cloud services (KVS/NoSQL object, caching, event control, unique ID, and others) are designed, developed, and engineered using resources readily available to z/OS and CICS without any special tools, languages, extensions, or other licensed software/hardware, according to Frerking. Other organizations can easily do the same to meet their own needs.

Building the Serverless Computing Environment 

Frerking explains that serverless computing and application development are similar in that organizations must first understand what is exactly required to support applications, but they are different in that an application developer requires no management of a server host.

The Parallel Sysplex within z/OS helps eliminate "single points of failure" from the hardware and operating system, as well as from the middleware and application software, which enables organizations to improve performance and availability. Frerking points out that the z/OS Parallel Sysplex's use of the Coupling Facility (CF) is crucial in supporting a serverless computing environment. The CF allows for high-speed caching, list processing, and locking. In turn, this provides extremely high availability and pooled/shared resources, which enables a robust serverless computing environment.

Additionally, he says that CICS is proven as a multi-tenancy, multi-language application server. Meanwhile, system management facilities provide charge-back to application and data access services, while z/OS Parallel Sysplex, workload manager, and TCP/SP provide elasticity. Frerking adds that state management can be developed using the CF and other pooled/shared resources.

Functions Best Served by Serverless Computing on z/OS

1. Data access services

2. Crypto services

3. Functions enabled by use of the Coupling Facility (e.g. Walmart's Unique ID Generating service)

To maximize a serverless computing environment, Frerking noted that organizations must design and develop data access services that utilize the CF of z/OS, such as VSAM/RLS and DB2. He adds that organizations also must establish REST access to applications as "Backend" Services and expose z/OS functions, such as crypto APIs. Any organization can create their own serverless computing environment with the tools and resources available in z/OS and CICS.

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