# Chapter 1. Overview

This chapter provides an architectural overview of Log Central, covering the following topics:

- Log Messages in System Management

- Agent/Manager Architecture

- Log Central and Enterprise Management Systems

- Data Collection Agents

- Log Central Components on the Managed Node

- Process Monitor

- Central Collector

## Log Messages in System Management

Log messages are typically used as a system management tool: to detect problems, track down the source of a fault, or track system performance. Distributed systems typically include a variety of software components that generate message logs, such as operating systems and relational database management systems (RDBMS). In the absence of any standard, software makers use different practices for message logging.

Log Central allows you to extract the information from these diverse logs and map the information into a common format. The information is maintained in a single relational database, providing a single point of access and a unified view of all information contained in log messages. This database approach improves the manageability of distributed systems.

A single failure, such as a file system filled to capacity, can generate a number of different log messages as the problem ripples through the affected software components. A unified view of the various messages means that the source of a problem can be more rapidly diagnosed.

All messages are stored in an RDBMS, and users can view the logs, generate reports, and do online monitoring through a set of graphical user interface tools-called the Log Central Console-and through several commands offered at the operating system level.

Also, each message is associated with a message definition, which includes information such as severity (degree of impact on the distributed system), probable cause of the message generated, and actions that need to be taken when it is logged. This information can be viewed and updated online by the administrator, who can use it to form a knowledge base for resolving problems.

Log information can be monitored "in real time" as it arrives at the Central Collector, using the Log Central Message Browser (part of the Log Central Console). The Central Collector stores management information in a relational database system which can be queried for analysis of problems or to track trends.

How to use the Log Central Console is discussed in Chapter 9, "Using the Log Central Console."

## Agent/Manager Architecture

Log Central is based on an agent/manager architecture, as shown in Figure 1-1. Local data collection agents run on machines where you have resources to be managed-these machines are called managed nodes. Local data collection agents forward log messages to the Central Collector. The Log Central Console, the Central Collector, and the Log Central relational database together play the "manager" role in the Log Central system.

The log agents monitor log messages generated by the resources that you wish to manage, such as messages logged to the UNIX syslog or NT event log, BEA TUXEDO userlogs, or relational database system logs. Agents map the information from these log messages into Log Central's uniform internal format for forwarding to the Central Collector. The data collection agents can be distributed around the network as needed.

To implement fault tolerance, users can configure a secondary Central Collector. If the primary Central Collector becomes unavailable, management information is automatically sent to the secondary Central Collector. Control automatically switches back to the primary Central Collector when it becomes available. Once the primary Central Collector becomes available again, the information sent to the secondary Central Collector is available to the primary Collector if the primary and secondary Central Collectors have been configured to use the same RDBMS.

How to configure a backup Central Collector is described in Chapter 6, "Host and Filter Configuration."

When no Central Collector is available to the data collection agent, the agent automatically stores the information in a temporary local backup file. Information in this file is automatically recovered and passed to the Central Collector when the Central Collector becomes available.

## Log Central and Enterprise Management Systems

Log Central allows you to integrate information from logs into an enterprise management system using Simple Network Management Protocol (SNMP). Both the data collection agents and the Central Collector have the ability to generate SNMP trap notifications. Two levels of trap configuration are available:

- A basic mapping of log messages to SNMP traps can be configured at the Central Collector using the Log Central Console Basic Trap Configuration window. The Central Collector generates SNMP traps when messages arrive that match the selected criteria. Using the Log Central Console Basic Trap Configuration is described in Chapter 9, "Using the Log Central Console."

- By editing the Log Central configuration file (`messaging.conf`), more complex criteria can be specified to select messages that trigger SNMP trap notifications. These criteria allow you to generate SNMP trap notifications from the distributed data collection agents. Defining agent filters to generate SNMP traps is described in Chapter 6, "Host and Filter Configuration."

  > Figure 1-1 Log Central in an Enterprise Network

Steps for integrating Log Central with your enterprise management system are described in Chapter 7, "Integrating Log Central with an SNMP Manager."

## Data Collection Agents

The data collection agent is made up of a Message Sender and one or more Log Monitors. Log Monitors monitor log messages generated by the resources that you wish to manage, such as messages logged to the UNIX `syslog` or Windows NT event log, BEA TUXEDO userlogs, or relational database system (RDBMS) logs. A distinct Log Monitor process is used on each managed node to monitor a particular log and map the information from incoming log messages to Log Central internal log format. The log messages are then forwarded to the Message Sender.

## Log Central Components on the Managed Node

The flow of information from the managed resource through the agent to the Central Collector is shown in Figure 1-2.

Note: Although two Log Monitors are shown in this diagram, the data collection agent can in fact have one or any number of Log Monitor processes. You must have a separate Log Monitor process for each log that you wish to monitor.

> Figure 1-2 Log Central Flow of Information

### Log Monitor

The Log Monitor reads the logs generated by the managed resource, such as a computer system, a BEA TUXEDO application, or a relational database system. Log Monitor maps the attributes in the managed resource log messages to attributes in Log Central messages. Messages are then placed in the Message Sender queue for forwarding to the Central Collector. You need a dedicated Log Monitor process for each managed resource.

Mapping of information into the Log Central internal format is provided out-of-the-box for the following logs:

- BEA TUXEDO user logs

- Oracle alert logs

- Windows NT event log

Message definitions are also provided out-of-the-box for these log resources.

This is an extensible system in that other log resources can be incorporated into Log Central as well. To manage other log resources you need to provide two things:

- A mapping to enable Log Monitor to translate the log messages into Log Central format.

You can define different mappings for the same log file-up to 20 different Log Central messages could be generated from a single message logged by the managed resource. How to devise mappings for log files is discussed in Chapter 4, "Integrating Logs into Log Central."

- Message definitions corresponding to the messages that will be forwarded by data collection agents to the Central Collector. A message definition template and command-line utilities are provided for loading message definitions when setting up the Log Central system. This is described in Chapter 5, "Creating and Loading Message Definitions."

For a list of all the procedures for setting up Log Central, refer to Chapter 2, "Getting Started."

### Message Sender

The Message Sender reads incoming messages from its queue and forwards them to its primary Central Collector. If the primary Central Collector is not available, the Message Sender sends the message to a secondary Central Collector if a secondary Central Collector has been defined. There should be one message sender for every managed node.

Agent filters can be defined for the Message Sender to do the following:

- Discard (not forward) specified messages

- Send a Simple Network Management Protocol (SNMP) trap notification when a specified message occurs

- Execute a script or program when a specified message occurs

- Store a specified message in a local file

Configuring filters is described in Chapter 6, "Host and Filter Configuration."

If none of the Central Collectors configured for this agent are accessible-due to a network outage, for example-the Message Sender writes messages retrieved from its queue to a temporary local file. When the Central Collector becomes available, the Message Sender automatically recovers all messages from the temporary file and forwards them to the Central Collector. When automatic recovery is occurring, new incoming messages have the highest priority and recovered messages are forwarded when the Message Sender is not preoccupied with new messages.

Temporary files are automatically deleted once the messages have been forwarded to the Central Collector.

If the Message Sender is unable to save messages in a temporary file, the messages are discarded and an SNMP trap is generated.

For information on starting and stopping Log Central processes on the managed node, refer to Chapter 8, "Starting and Stopping Log Central."

## Process Monitor

The Process Monitor (`proc_monitor`) is a daemon that runs on all managed nodes and the central host. The Process Monitor is started whenever the `start_messaging` command is invoked on a particular machine. The following processes "register" with the Process Monitor at startup time:

- `start_messaging`

- Log Monitor (`log_monitor`)

- Message Sender (`msg_sender`)

- Message Receiver (`msg_receiver`)

- Message Processor (`msg_processor`)

The Process Monitor awakens at fixed intervals and checks all registered processes. If configured to do so, it restarts any dead processes. The Process Monitor restarts the processes with the user and group IDs that were passed to it at startup.

## Central Collector

The Central Collector performs the following functions:

- Log information collected by the distributed data collection agents is forwarded to the Central Collector. The Central Collector is your central point of access to the stream of information flowing from distributed log agents. When you monitor incoming messages using the Log Central Message Browser, the Central Collector provides the messages to the Message Browser as they arrive from the log agents.

- The Central Collector is responsible for inserting incoming messages into the Log Central database. The Log Central database may be located either on the central host or on another machine in your network. The Central Collector is your point of access to the historical log data maintained in the database. When you make queries for historical log data through the Log Central Message Browser, the Central Collector processes your requests, retrieves the requested data from the database, and sends the data to the Message Browser.

- The Log Central Console Basic Trap Configuration window allows you to do basic configuration of SNMP trap notifications generated by the Central Collector. More advanced conditions can be defined for generating SNMP traps using agent filters. These are defined by editing the Log Central configuration file (`messaging.conf`) on the central host.

- The Central Collector is also your point of access to the message definitions maintained in the Log Central database. Requests for viewing or modifying message definitions from the Message Definition Editor are processed by the Central Collector.

For fault tolerance, you can configure two Central Collectors with one serving as the backup or secondary collector in case the primary Central Collector goes down or is unavailable.

The Central Collector is made up of two processes, the Message Receiver and the Message Processor. The flow of information at the Central Collector is shown in Figure 1-3.

> Figure 1-3 Log Central Components on the Central Host

### Message Receiver

Messages from the distributed data collection agents arrive at the Message Receiver. The Message Receiver stores the incoming messages in an intermediate file. A new intermediate file is created every hour. You can control how frequently the intermediate files are deleted using the Log Central Console Storage Maintenance tool.

For information on using the Storage Maintenance tool, refer to Chapter 9, "Using the Log Central Console."

The Message Receiver generates an enterprise-specific SNMP trap if it cannot log messages to an intermediate file. The number of failures that triggers a trap is defined by the `BEA_LC_TRAP_EVERY_FAILURES` environment variable. If this environment variable is not set, a trap is generated every 100 failures. The SNMP trap has an enterprise-specific trap number of 90101.

### Message Processor

The Message Processor performs the following functions:

- Reads messages from intermediate files and inserts these messages into the Log Central relational database.

- Handles user-initiated requests from Log Central Consoles, such as database queries or forwarding of incoming messages for online monitoring.

- Generates SNMP trap notifications if the user has enabled trap generation at the Central Collector. This can be configured using the Log Central Console Basic Trap Configuration window. Traps can be generated either on the basis of severity or the message definition. How to do Basic Trap Configuration is described in Chapter 9, "Using the Log Central Console."