Overview
The ACS Logging System is comprised of several pieces of software available for different programming languages. There are 4 main pieces or concepts regarding the logging system:
- Logging technology
- Logging implementation
- Notification Channel
- Central Logger
- *ACS Log Service
* The ACS Log Service is only used by the Python logging implementation, but it could be used by any ACS / CORBA application.
Logging Technology
The logging technology is the underlying library, package or framework that is used to enable the ACS logging system. Each programming language is based and/or compatible with at least one logging technology. The current support is the following:
- Python
- Logging facility for Python
- Java
- JDK Logger
- SLF4J
- Log4j2
- C++
- ACE Logging
Log4CPP
Each of these technologies is integrated with different ad-hoc techniques intrinsic to the mechanics and best practices they have, but also due to existing restrictions at the time of design and implementation that may no longer be there.
Logging Implementation
The logging implementation is the programming language specific code to integrate one or more of the logging technologies into ACS. The code for each of the programming languages is in different modules:
- Python: ACS/LGPL/CommonSoftware/acspycommon
- Java: ACS/LGPL/CommonSoftware/acsjlog
- C++: ACS/LGPL/CommonSoftware/logging
Python
The Python logging implementation is based in the standard Python 'logging' module. Some conventions are introduced to standardize log levels among the implementations as well as other convenient functionalities. The logging.Logger class is specialized for ACS by defining a local and a remote handler.
The local handler just formats the logs in a convenient way to stdout, while the central handler takes advantage of the ACS Log Service to distribute the logs to any interested client.
Java
C++
Notification Channel
The Notification Channel is a CORBA service for decoupled messaging through events. We're currently using the implementation provided by ACE/TAO through the Notify Service. For more details please look at the Notification Channel technical document.