Autosys – Architecture
The following are the main AutoSys system components:
- Event server (AutoSys database)
- Event processor
- Remote agent
Event Server
The event server or AutoSys database (the RDBMS) is the data repository for all system information and events as well as all job, monitor, and report definitions. Event server refers to the database where all the AutoSys information, events, and job definitions are stored. Occasionally, the database is called a data server, which actually describes a server instance. That is, it is either a UNIX or Windows process, and it is associated data space (or raw disk storage), that can include multiple databases or tablespaces.
High-Availability Option: Dual-Event Servers
AutoSys can be configured to run using two databases, or dual-event servers. This feature provides complete redundancy. Therefore, if you lose one event server due to hardware, software, or network problems, AutoSys operations can continue on the second event server without loss of information or functionality. For various reasons, database users often run multiple instances of servers that are unaware of the other servers on the network. When implementing AutoSys, the database can run stand-alone for AutoSys only, or it can be shared with other applications.
Event Processor
The event processor is the heart of AutoSys; it interprets and processes all the events it reads from the AutoSys database. Sometimes called the event_demon, the event processor is the program, running either as a UNIX process or as a Windows service that actually runs AutoSys. It schedules and starts jobs. After you start it, the event processor continually scans the database for events to be processed. When it finds one, it checks whether the event satisfies the starting conditions for any job in the database. Based on this information, the event processor first determines what actions are to be taken, then instructs the appropriate remote agent process to perform the actions. These actions may be the starting or stopping of jobs, checking for resources, monitoring existing jobs, or initiating corrective procedures.
High-Availability Option: Shadow Event processor
AutoSys lets you set up a second event processor, called the shadow event processor. This second processor should run on a separate machine to avoid a single point of failure. The shadow event processor remains in an idle mode, receiving periodic messages (pings) from the primary event processor. Basically, these messages indicate that all is well. However, if the primary event processor fails for some reason, the shadow event processor will take over the responsibility of interpreting and processing events.
Remote Agent
On a UNIX machine, the remote agent is a temporary process started by the event processor to perform a specific task on a remote (client) machine. On a Windows machine, the remote agent is a Windows service running on a remote (client) machine that is directed by the event processor to perform specific tasks. The remote agent starts the command specified for a given job, sends running and completion information about a
task to the event server, then exits. If the remote agent is unable to transfer the information, it waits and tries again until it can successfully communicate with the database.
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