Modernizing with Confidence: WebSphere Application Server’s Legacy and Future in IT Infrastructure
For "z/OS and Friends," Dr. Joe Gulla inspects IBM WebSphere Application Server's (WAS) deep integration with the mainframe
IBM WebSphere Application Server (WAS) has had incredible growth over 13 major releases since the initial one in 1998. Today, Many thousands of companies are using it globally, taking advantage of incredible functionality that offers developers, team leaders and executives an array of implementation choices.
Let’s take a look at how we got here and where WAS is going.
WAS and IBM Web Hosting
When WAS arrived, web hosting was starting to take off in the IT industry. Many companies were setting up their web presence, and some were seeking help to do that. There were no offerings labelled as “cloud services,” so almost all the servers were dedicated to the specific customer.
IBM had a group of web experts who hosted special events, mostly major sporting happenings, with a huge web audience. The group knew how to scale up for big events and keep the systems from crashing or locking up. Handling peak usage on this scale was new ground. IBM also had many customers who had outsourced systems and applications in IBM data centers like the one in Research Triangle Park in North Carolina where I worked. This combination of expertise and a raised floor resulted in IBM web hosting “farms” in secure and power-redundant data centers.
WAS became part of the standard build for customer servers running Solaris, Windows and AIX. Along with WAS came utilities and other products like databases that needed to be supported and maintained. Customers didn’t just need space, but many counted on IBM to install and maintain software and provide support services. At this time, there were many challenges, but the skills of the implementation teams were growing by the day.
What Operating Systems and Platforms?
WAS has had a deep and evolving relationship with z/OS, since WebSphere Application Server for z/OS (WASz) was first released in 2001. That support came with WAS version 4.01. Currently, WASz provides full Java EE support on the mainframe. It also integrates with core z/OS subsystems like CICS, IMS, DB2 and batch jobs, allowing Java applications to interact with application resources of long standing. In addition to z/OS, WAS runs on other key operating systems and platforms as shown in Table 1.
Table 1. WAS Operating System and Platform Support
| OS/Platform | Named Implementation |
| Linux | Red Hat Enterprise Linux (RHEL) SUSE Linux Enterprise Server (SLES) Ubuntu (Liberty only) Note: WAS is popular for containerized deployments and cloud-native environments. |
| Windows | Windows Server Windows 10/11 (for development and testing) |
| AIX | Versions 7.2 and 7.3 Note: IBM’s UNIX operating system for Power systems is frequently used in high-performance, mission-critical environments. |
| IBM i | WAS Liberty supports IBM i for running Java workloads on Power systems. |
| Solaris | Older versions of WAS supported Solaris on SPARC and x86, but support has been phased out in recent releases. Note: IBM recommends migrating to platforms with full support, such as Linux, AIX, Windows, IBM I or z/OS. |
| Cloud Platforms | IBM Cloud AWS Microsoft Azure Google Cloud Platform Note: Liberty is optimized for containers including Docker, Kubernetes and OpenShift, as well as cloud-native deployment. |
What About z/OS Subsystem Integration?
WAS runs as a standard subsystem on z/OS. As it runs, it becomes part of a platform that has the unique capacity for running hundreds of heterogeneous workloads concurrently and meeting service level objectives as defined by the user.
WAS Workloads Can Be Consolidated
A mainframe can be used to consolidate workloads from many individual servers. In the industry, this is called a “server consolidation play” but this is not a game. Rather, it is an opportunity. As there is often a large administration overhead or a physical capacity concern from using many individual servers, the mainframe can take on the role of a single server environment managing those workloads. Consolidation typically results in cost savings and simpler operating processes.
WAS Security Made Stronger
The combination of zSeries hardware- and software-based security, along with incorporated J2EE security, offers significant defense against possible intrusions. The J2EE security is a layered architecture built on top of the operating system. It is a policy-based, fine-grain access control mechanism.
WAS Workloads Experience High Availability by Design
WASz uses the zSeries platform’s internal error detection and correction capabilities. WASz has recovery termination management that detects, isolates, corrects and recovers from software errors. WASz can differentiate and prioritize work based on service level agreements that are carried out by the z/OS Workload Manager (WLM) component. WASz offers clustering capability as well as the ability to make non-disruptive changes to software components, such as resource managers.
WAS Performance Can Be Enhanced
WASz uses the mainframe qualities in hardware, and software characteristics incorporating WLM definitions (service classes, report classes, and enclaves), dynamic LPAR configuration and Parallel Sysplex functionality. Classic WASz uses a control region (CR) and multiple servant regions (SRs), each with its own JVM. This design supports scalability and isolation of workloads.
What Is the Liberty Profile on z/OS?
WAS Liberty was introduced in 2012. Liberty is a lightweight, modular version of WAS. On z/OS, Liberty merges CR and SRs into a single JVM, reducing startup time and resource usage. Liberty allows feature selection, so only needed components are loaded.
Since z/OS 2.3 (2017), IBM includes z/OS Liberty Embedded with the base OS. It is used by many IBM products like z/OSMF, IBM z/OS Connect EE, CICS (Java programs via JCICS) and IBM MQ web console. Here are details about how it is maintained by IBM.
What Companies in What Industries Use WAS?
Let’s broaden the discussion and look at what companies use WAS and discover the many reasons to use WAS today and into the future. According to Landbase GTM Intelligence, the thousands of companies that utilize WAS span industries such as:
- Apparel and accessories retail
- Department stores, shopping centers and superstores
- Computer equipment and peripherals
- Database and file management software
- Drug stores and pharmacies
- Telecommunication equipment
- Crops
- Custom software and IT services
Typical users range from mid-sized businesses to large enterprises with thousands of employees and billions in revenue. Examples of major companies using WAS include Amazon, Walmart, Apple, Microsoft, CVS Health, Huawei, Samsung, Cargill, McKesson and IBM itself. WAS software remains a critical component in enterprise IT for these customers for many reasons.
There Are Many Reasons to Include WAS in Your Application Development Portfolio
Here are the main reasons to employ WAS, whether on z/OS, distributed platforms or cloud environments. Each reason includes a brief explanation (in summary form) of its value. I organized them in five categories as you will see in Table 2. All 25 summary-form reasons are explored in the section following Table 2.
Table 2. Reasons to Use WAS
| Category | Reason in Summary Form |
| 1. Principal capabilities and architecture | |
| Full Java EE support | |
| Modular runtime with Liberty Profile | |
| Classic Profile for full functionality | |
| Flexible deployment models | |
| Containerized runtime separation | |
| 2. Integration and compatibility strengths | |
| Deep integration with z/OS subsystems | |
| Cross-platform consistency | |
| Support for open standards | |
| Connectors for enterprise information systems | |
| Support for REST and SOAP web services | |
| 3. Performance and scalability impacts | |
| Vertical scalability on z/OS | |
| Horizontal scalability via Sysplex clustering | |
| Optimized JVM performance | |
| Efficient resource management | |
| Reduced CPU and memory footprint | |
| 4. Security and reliability strengths | |
| Robust security model | |
| High availability features | |
| Disaster recovery integration | |
| Secure API gateway with z/OS Connect EE | |
| Auditing and monitoring tools | |
| 5. Operational and strategic advantages | |
| Included with z/OS base (Liberty embedded) | |
| Skill portability across platforms | |
| Reduced total cost of ownership | |
| Support for DevOps and CI/CD | |
| Strategic IBM commitment |
Category 1: Principal Capabilities and Architecture
Five reasons related to WAS capabilities and architecture are explored in the section below:
Full Java EE Support
WAS supports full Java EE (Jakarta EE) standards, enabling enterprise-grade application development and deployment. Java remains one of the most widely used programming languages in the world, especially in enterprise environments. It provides platform independence, a huge ecosystem, performance and optimization and backward compatibility. Plus, it is cloud- and microservices-ready.
Modular Runtime with Liberty Profile
Liberty is significant because it is lightweight and fast-starting and allows selective feature loading. It also improves performance and reduces resource usage as compared to traditional WAS profiles. It is a good fit for certain kinds of uses like new, cloud-native, micro-service-based applications.
Classic Profile for Full Functionality
The term “WAS Classic profile” refers to the traditional, full-featured version of IBM WebSphere Application Server. The Classic profile offers strong enterprise features like EJBs, JMS and full J2EE stack for complex workloads.
Flexible Deployment Models
WAS supports Base and Network Deployment configurations, allowing scalability from single-server setups to clustered environments. The discussion of deployment models also extends to cloud and container-based deployments and development-specific deployment models that might include an administrative console or command-line tools. It supports all these different ways to deploy an application.
Containerized Runtime Separation
Containerized runtime separation is critical for enhancing security, especially in multi-tenant environments, by providing stronger isolation between containers and the underlying host operating system. Web and EJB containers isolate runtime components, improving manageability and fault tolerance. Since applications are getting more complex, containers help alleviate pain points.
Category 2: Integration and Compatibility Strengths
Five reasons related to integration and compatibility are explored in the section below:
Deep Integration With z/OS Subsystems
WASz integrates with CICS, IMS, Db2 and MQ primarily through an API gateway called IBM z/OS Connect to expose transaction processors like CICS as RESTful APIs. This helps with data sharing, transaction management and message queuing to support hybrid cloud environments and modern AI initiatives.
Cross-Platform Consistency
Applications written with WAS behave the same across z/OS, Linux, Windows and cloud platforms due to consistent APIs and tooling. While WAS aims for consistency, performance tuning and integration will likely differ across platforms. Additionally, external dependencies like file paths and OS-level services may require platform-specific handling. Note: The same version of WAS should be used across platforms to avoid inconsistencies in features or behavior.
Support for Open Standards
WAS adheres to standards like HTTP, HTML, CORBA, IIOP and J2EE, ensuring interoperability. Using open standards, J2EE helps to ensure interoperability and data exchange between different systems. This fosters competition and innovation while reducing vendor lock-in.
Connectors for Enterprise Information Systems
WAS Connectors for enterprise information systems (EIS) are a key component of IBM’s WebSphere platform. The connectors enable applications to interact with backend systems like databases, enterprise resource planning (ERP) software and mainframes. These connectors, also known as resource adapters, are based on the Java EE Connector Architecture (JCA) standard.
Support for REST and SOAP Web Services
WAS has support for web services, which enables modern API-based architectures and legacy SOAP-based integrations. Web services are critically important to developers today, as they enable different software systems to communicate, share data and function across platforms and devices.
Category 3: Performance and Scalability Impacts
Five reasons related to performance and scalability are explored in the section below:
Vertical Scalability on z/OS
WAS leverages z/OS’s efficient I/O and dynamic resource allocation for high-performance workloads. The z/OS channel subsystem architecture provides superior I/O throughput and efficiency as z/OS uses a dedicated I/O subsystem that offloads I/O processing from the main CPU. This design enables high-speed data transfer and reduces CPU overhead. z/OS also has high-speed I/O interfaces using technologies like FICON and zHPF (High Performance FICON. z /OS provides extremely fast access to disk, which benefits WAS applications with heavy data access needs.
Horizontal Scalability via Sysplex Clustering
WAS can scale across multiple LPARs using Parallel Sysplex for high availability. The ability to leverage this technology makes a difference for applications that require a clustering solution that can support up to 32 mainframes to be linked to form a single logical computing platform.
Optimized JVM Performance
The latest version of Java on z/OS supported with WAS is Java SE 21 which is a Long-Term Support (LTS) release that includes significant performance enhancements and features that contribute to improved application performance and efficiency. Key performance characteristics include:
1. Generational Z Garbage Collector (ZGC)
2. Virtual Threads (Project Loom)
3. JVM and Core Library Optimizations
4. Language Feature Contributions to Performance
These are 4 areas specifically focused on performance.
Efficient Resource Management
WAS uses control and servant regions to manage workloads efficiently on z/OS. This separation of duties between control regions and servant regions helps to manage workloads efficiently. This architecture works with the z/OS WLM to balance resources, optimize performance, and ensure high availability.
Reduced CPU and Memory Footprint
Liberty’s reduced CPU and memory footprint is achieved through its lightweight design, including modular features and efficient runtime architecture, and can be further optimized by tuning Java Virtual Machine (JVM) settings, disabling unneeded features, and reducing idle CPU time by tailoring config parameters.
Category 4: Security and Reliability Strengths
Five reasons related to security and reliability are explored in the section below:
Robust Security Model
The integration of WASwith the system authorization facility (SAF), combined with EAL5 certificationand secure cross-memory communication, provides enterprise-grade security on the z/OS mainframe platform. This combination delivers high assurance for mission-critical systems by controlling resource access and isolating application processes. Note:configurations of z/OS, such as the PR/SM LPARs for secured isolation, are certified at the EAL5+ level.
High Availability Features
WAS supports failover, clustering and workload balancing for 24×7 operations. These options are especially robust and flexible when WAS is running on System Z. WAS supports failover, clustering and workload balancing on Linux as well. These are standard features of WAS, particularly the Network Deployment (ND) and Liberty versions, which are designed for high availability and scalability in production environments.
Disaster Recovery Integration
WAS fully supports sysplex distributor and dynamic virtual IP addressing (DVIPA) for disaster recovery and failover scenarios in a z/OS Parallel Sysplex environment. This configuration provides high availability and workload balancing for WAS applications running on the mainframe. WAS Network Deployment has well-documented implementation details.
Secure API Gateway With z/OS Connect EE
WAS Liberty powers z/OS Connect EE, which enables secure RESTful access to mainframe assets. The API gateway is a way to access systems of record, written in COBOL or BAL, and utilize their processing and access to data without changing them or writing other COBOL and BAL programs.
Auditing and Monitoring Tools
Each environment where WAS runs has mature tools for chargeback, SLA monitoring and performance tracking. WAS has the Performance Monitoring Infrastructure (PMI) system and other tools to help monitor the overall health of the application server.
Category 5: Operational and Strategic Advantages
Five reasons related to important advantages are explored in the section below:
Included With z/OS Base (Liberty Embedded)
Liberty is bundled with z/OS since v2.3, reducing acquisition and installation overhead. IBM maintains the z/OS Liberty Embedded base element through the system-managed building (SMB) process using SMP/E. This allows for digital signing and verification of software packages to ensure their integrity.
Skill Portability Across Platforms
Common administrative interfaces and tooling allow teams to manage WAS across environments. This common approach allows skills developed on one platform (on-premises, cloud environments and hybrid infrastructures) to be easily transferred to another, saving time and improving software quality. This allows developers and administrators to apply the same expertise to applications running on-premises, on mainframes or in multiple cloud environments, including containerized deployments.
Reduced Total Cost of Ownership
Consolidation, virtualization and specialty processors, for example IBM z Integrated Information Processor (zIIP), reduce hardware and software costs. Server consolidation, using z/OS, is a cost takeout strategy. It also simplifies operations. Virtualization, through LPARs or VMs, is a proven way to support consolidation without buying additional servers. zIIP processors lower the overall cost of mainframe software by running workloads that would otherwise incur higher charges on general-purpose CPs.
Support for DevOps and CI/CD
WAS supports DevOps and CI/CD through its adaptable runtimes, command-line tools and native integration with modern orchestration platforms like Kubernetes. Both the traditional WAS and the lightweight Liberty profile offer features to automate the software delivery lifecycle, from development to production. There is an IBM Redbook, “Using Liberty for DevOps, Continuous Delivery, and Deployment,” that directly addresses this opportunity for project managers and developers.
Strategic IBM Commitment
IBM continues to invest in WAS across platforms, ensuring long-term viability and innovation. 13 major releases since the initial one in 1998 is a substantial record of support and commitment from IBM. When you dig in and explore WAS, you immediately realize that IBM supports this product with continued innovation.
Note on Sources in the Previous Section on Reasons to Use WAS
Here is an explanation of the two main sources used in the previous section:
1. Introduction to WebSphere Application Server for z/OS
This is a very useful article on WAS that is part of the z/OS Basic Skills materials. In addition to an introduction to Application Server for z/OS, the article contains four other detailed sections:
- J2EE application model on z/OS
- Running WebSphere Application Server on z/OS
- Application server configuration on z/OS
- WebSphere Application Server connectors for Enterprise Information Systems
2. Websphere Application Server – Now An Essential Part of z/OS
This article, from April 22, 2021, is by David Stephens. It contains useful information and is divided into sections:
- WebSphere Application Server on z/OS
- Who Uses WASz?
- Not the Only Java Option
What Is Next?
In the next article, I will focus on IBM HTTP Server (IHS) and others in this category. I have questions that I will answer related to:
- How is it used and by whom?
- What “space” does IHS occupy?
- What are the other web servers of this kind in the industry? (I am interested in both open-source and proprietary/enterprise web servers.)
- Which web servers are “at home” on z/OS?