ITA - IT Architecture

Enhanced Definition

IT Architecture, within the mainframe context, is the comprehensive blueprint and design principles that guide the structure, behavior, and implementation of an organization's entire information technology environment on the z/OS platform. It encompasses the hardware, software, data, and network components, ensuring they align with business objectives, performance requirements, security policies, and operational efficiency. Its primary purpose is to provide a holistic, strategic view for developing, integrating, and managing critical enterprise systems.

Key Characteristics

- Holistic Scope: Covers all layers from the physical zSystem hardware, z/OS operating system, middleware (e.g., CICS, IMS, MQ), databases (DB2, IMS DB), applications (COBOL, PL/I, Java), to network connectivity and security controls.
- Performance and Scalability Focus: Designs for the unique high-volume transaction processing, low-latency, and massive data handling capabilities inherent to the z/OS platform, leveraging features like Sysplex and data sharing.
- Resilience and Availability: Emphasizes high availability (HA), disaster recovery (DR), and business continuity through robust configurations, GDPS solutions, and replication technologies.
- Security Integration: Incorporates enterprise security managers like RACF (or equivalent ESM), encryption standards, network segmentation, and auditing as fundamental design elements from inception.
- Cost Optimization: Considers the unique cost model of mainframe software (MLC - Monthly License Charge) and hardware, aiming for efficient resource utilization and workload management to optimize operational expenses.
- Legacy and Modernization Balance: Must account for the vast existing COBOL and PL/I application portfolios while integrating new technologies, APIs, cloud integration, and DevOps practices on z/OS.

Use Cases

- New Application Development: Designing the end-to-end architecture for a new mission-critical application, including choice of transaction manager (CICS vs. IMS TM), database (DB2 vs. IMS DB), integration patterns, and deployment within a Sysplex.
- System Modernization and Transformation: Planning the phased evolution of existing mainframe applications to leverage newer z/OS capabilities, such as exposing COBOL programs as REST APIs via z/OS Connect or adopting Java on z/OS.
- Disaster Recovery and Business Continuity Planning: Architecting a robust DR solution using GDPS or other replication technologies to ensure rapid recovery and minimal downtime for critical business services.
- Performance and Capacity Planning: Analyzing the current architecture to identify bottlenecks, optimize resource allocation, and plan for future growth in transaction volumes or data storage.
- Security Posture Enhancement: Reviewing and improving the overall security architecture of the mainframe environment, including RACF policies, data encryption at rest and in transit, and compliance with industry regulations.

Related Concepts

IT Architecture provides the strategic roadmap that governs the implementation and interaction of specific mainframe technologies. It dictates how z/OS, CICS, DB2, IMS, JCL, and COBOL applications are deployed, configured, and integrated to form a cohesive, high-performing enterprise system. It directly influences System Programming decisions, Application Development standards, and Operations procedures, ensuring that all components of the mainframe ecosystem are aligned to meet business objectives and non-functional requirements.

Best Practices:

Adopt a Reference Architecture: Leverage IBM's z/OS reference architectures or industry-standard patterns as a foundation, customizing them to meet specific organizational requirements and constraints.
Prioritize Non-Functional Requirements (NFRs): Design with performance, security, availability, scalability, and recoverability as primary considerations from the outset, rather than addressing them as afterthoughts.
Document Thoroughly and Consistently: Maintain comprehensive, up-to-date documentation of the architecture, including logical and physical diagrams, component specifications, data flows, and interface definitions.
Regular Review and Audit: Periodically review and audit the architecture to ensure its continued alignment with evolving business goals, security policies, technological advancements, and regulatory compliance.
Embrace Hybrid Cloud Integration: Design for seamless and secure integration with off-platform services and hybrid cloud environments, utilizing technologies like z/OS Connect, MQ, and API management