WTOR - Write to Operator with Reply

Enhanced Definition

WTOR (Write to Operator with Reply) is a type of message issued by the z/OS operating system or an application program that requires an explicit response from the system operator. Its primary purpose is to solicit a decision or action from the operator, which is often critical for system management, problem resolution, or resource allocation.

Key Characteristics

- Operator Interaction: Explicitly designed to prompt an operator for input, unlike a simple WTO (Write To Operator) which is informational.
- Reply Identifier (Reply ID): Each WTOR is assigned a unique reply ID (e.g., R 01, 'YES') that the operator uses to direct their response to the correct message.
- Blocking vs. Non-blocking: A program issuing a WTOR can either wait (block) for the operator's reply before continuing execution or proceed asynchronously, processing the reply later.
- System Console Display: WTORs are displayed on the z/OS system console, which is the primary interface for operators to monitor and control the system.
- Automation Potential: Many WTORs, especially routine ones, are intercepted and responded to automatically by z/OS automation software like SA z/OS or NetView, reducing manual intervention.
- Message Format: Typically includes a message ID (e.g., IEF238D), descriptive text, and often specifies valid reply options.

Use Cases

- Mounting Removable Media: Requesting the operator to mount a specific tape volume or removable disk pack for a job step.
- Resource Contention Resolution: Prompting the operator to make a decision when a critical resource (e.g., a dataset, device) is contended or unavailable.
- System Shutdown/IPL Options: Offering the operator choices during system initialization (IPL) or shutdown procedures, such as whether to perform a warm or cold start.
- Application Error Handling: Allowing an application to request operator intervention for an unexpected condition or an ABEND that might require a specific recovery action.
- Security Confirmation: Requiring operator confirmation for sensitive system commands or actions that could impact system integrity or data security.

Related Concepts

WTORs are a fundamental part of the z/OS message services, working in conjunction with WTOs (Write To Operator) to provide comprehensive communication between the system, applications, and operators. They are often issued by programs executed via JCL or initiated by system components, with responses managed through the z/OS system console. Modern automation software like NetView or SA z/OS heavily relies on intercepting and responding to WTORs to minimize human interaction and improve system availability.

Best Practices:

Minimize Usage: Use WTORs sparingly and only when operator intervention is truly necessary; for informational messages, use WTO to avoid unnecessary interruptions.
Clear and Concise Messaging: Ensure the WTOR message is clear, concise, and provides all necessary information for the operator to make an informed decision, including valid reply options.
Automate Responses: Implement automation scripts (e.g., using REXX, CLIST, or automation products) to automatically respond to routine or predictable WTORs, reducing operator workload and response time.
Implement Timeouts: Design applications to include timeouts for WTORs to prevent indefinite waits if an operator does not respond, allowing for alternative error handling or recovery paths.
Robust Error Handling: Program applications to gracefully handle invalid or unexpected replies from the operator, preventing application failures due to incorrect input.