The ZOOM Error Logger package is meant to meet the needs of Run II (D0 and CDF) offline (and possibly higher-level online) code for a unified message logging and statistics facility.

• Fundamentals and Concepts
• How the Physicist Logs Errors
• Frameworker's Basics of Error Loggers
• Further Options for the Frameworker
• Collective Error Logging
• Error Logging for Multithreaded Processes
• Graded Assertions Interfacing with the Error Logger
• Customization Hooks

This package provides:

• Uniform formatting of log messages
• Central control of logging to multiple destination logs
• Throttling by severity of messages to each destination
• Setting limits on appearances (by message id) of each sort of message
• Error statistics by message id, module, and subroutine
• Collective (multiprocess) error reporting (with the user supplying the communications mechanism)
• Error message history, via a filtered list of ErrorObj's.
• Assertion macros reporting via error messages

Some design points of this package are

• The semantics of providing information to a log message are those of streaming objects into the log. Thus the full power of the << mechanism for any object that may be sent to an ostream is available.
  Here is a very brief description of how users issue messages for the log.
• It is assumed that most of the time, messages are not being logged. The burden in time incurred by the presence of the mechanism is kept absolutely minimal in such circumstances.
• Much attention has been paid to the potential for use in the D0 Level 2 environment, in which efficienciy considerations are extreme and notable restrictions are placed on C++ feature usage. The design is such that customization for that purpose can be done with maximal retention of the ErrorLogger code.

Although this package did not start out with a design goal of becoming a not a multi-process message gathering mechanism, the ELcollected destination allows an experiment to set up collective error message handling, based on whatever communications mechanism they choose to employ. Given this collection mechanism, the need for a "circular save buffer" (which had previously been called ELsaveBuffer) is also greatly simplified. The necessary functionallity is met by a destination ELerrorList, which places error objects onto a user-accessible std::list.

This package may be obtained from the following sources:

• The ZOOM reference copy is located on the Fermilab fnalu Unix cluster (for example, on fsgi02.fnal.gov), in directories rooted at /afs/fnal.gov/files/reports/working-groups/fpcltf/Pkg/ErrorLogger.
• For CDF or D0 users, a reference copy is maintained in the standard CDF or D0 manner on their respective Unix systems.
• The package is kept in a CVS repository managed by SoftRelTools. A file cvs.setup provides a script for setting up this and/or other ZOOM products.

• Fundamentals and Concepts
• How the Physicist Logs Errors
• Frameworker's Basics of Error Loggers
• Further Options for the Frameworker
• Collective Error Logging
• Error Logging for Multithreaded Processes
• Graded Assertions Interfacing with the Error Logger
• Customization Hooks
• Design Notes and details of syntax and semantics
  includes all the above sections, plus technical details.

• Very basic usage
• Sample framework illustratiing the use of many of the common features
• Using ELcollected/ELrecv to implement centralized message collection
• Using ELerrorList for in-code examination of error message history

• ZMexAugmented.