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package com.unboundid.directory.sdk.examples;
import java.io.File;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import com.unboundid.directory.sdk.common.api.AlertHandler;
import com.unboundid.directory.sdk.common.api.DiskSpaceConsumer;
import com.unboundid.directory.sdk.common.config.AlertHandlerConfig;
import com.unboundid.directory.sdk.common.types.AlertNotification;
import com.unboundid.directory.sdk.common.types.LogSeverity;
import com.unboundid.directory.sdk.common.types.RegisteredDiskSpaceConsumer;
import com.unboundid.directory.sdk.common.types.ServerContext;
import com.unboundid.ldap.sdk.LDAPException;
import com.unboundid.ldap.sdk.ResultCode;
import com.unboundid.util.StaticUtils;
import com.unboundid.util.args.ArgumentException;
import com.unboundid.util.args.ArgumentParser;
import com.unboundid.util.args.FileArgument;
/**
* This class provides a simple example of an alert handler which will write
* information about each alert notification to a file in a specified directory.
* The file will be named with the alert ID. It has one configuration argument:
* <UL>
* <LI>alert-directory -- The path to the directory in which files will be
* written about alerts that are generated.</LI>
* </UL>
*/
public final class ExampleAlertHandler
extends AlertHandler
implements DiskSpaceConsumer
{
/**
* The name of the argument that will be used to specify the path to the
* directory in which to write alert files.
*/
private static final String ARG_NAME_ALERT_DIR = "alert-directory";
// The current configuration for this alert handler.
private volatile AlertHandlerConfig config;
// The directory in which to write alert files.
private volatile File alertDirectory;
// The registered disk space consumer for this alert handler.
private volatile RegisteredDiskSpaceConsumer registeredConsumer;
// The server context for the server in which this extension is running.
private ServerContext serverContext;
/**
* Creates a new instance of this alert handler. All alert handler
* implementations must include a default constructor, but any initialization
* should generally be done in the {@code initializeAlertHandler} method.
*/
public ExampleAlertHandler()
{
// No implementation required.
}
/**
* Retrieves a human-readable name for this extension.
*
* @return A human-readable name for this extension.
*/
@Override()
public String getExtensionName()
{
return "Example Alert Handler";
}
/**
* Retrieves a human-readable description for this extension. Each element
* of the array that is returned will be considered a separate paragraph in
* generated documentation.
*
* @return A human-readable description for this extension, or {@code null}
* or an empty array if no description should be available.
*/
@Override()
public String[] getExtensionDescription()
{
return new String[]
{
"This alert handler serves an example that may be used to demonstrate " +
"the process for creating a third-party alert handler. It will " +
"create a file in a specified directory for each alert " +
"generated within the server. The file will be human-readable " +
"but not particularly machine-parseable.",
"Because this alert handler writes to disk, it also serves as an " +
"example of a disk space consumer so that the server may track " +
"available space on the disk containing the alert files and " +
"potentially warn administrators if usable space becomes too low."
};
}
/**
* Updates the provided argument parser to define any configuration arguments
* which may be used by this alert handler. The argument parser may also be
* updated to define relationships between arguments (e.g., to specify
* required, exclusive, or dependent argument sets).
*
* @param parser The argument parser to be updated with the configuration
* arguments which may be used by this alert handler.
*
* @throws ArgumentException If a problem is encountered while updating the
* provided argument parser.
*/
@Override()
public void defineConfigArguments(final ArgumentParser parser)
throws ArgumentException
{
// Add an argument that allows you to specify the alert directory.
Character shortIdentifier = null;
String longIdentifier = ARG_NAME_ALERT_DIR;
boolean required = true;
int maxOccurrences = 1;
String placeholder = "{path}";
String description = "The path to the directory in which alert " +
"files should be written. Relative paths will be relative to the " +
"server root.";
boolean fileMustExist = true;
boolean parentMustExist = true;
boolean mustBeFile = false;
boolean mustBeDirectory = true;
parser.addArgument(new FileArgument(shortIdentifier, longIdentifier,
required, maxOccurrences, placeholder, description, fileMustExist,
parentMustExist, mustBeFile, mustBeDirectory));
}
/**
* Initializes this alert handler.
*
* @param serverContext A handle to the server context for the server in
* which this extension is running.
* @param config The general configuration for this alert handler.
* @param parser The argument parser which has been initialized from
* the configuration for this alert handler.
*
* @throws LDAPException If a problem occurs while initializing this alert
* handler.
*/
@Override()
public void initializeAlertHandler(final ServerContext serverContext,
final AlertHandlerConfig config,
final ArgumentParser parser)
throws LDAPException
{
serverContext.debugInfo("Beginning alert handler initialization");
this.serverContext = serverContext;
this.config = config;
// Get the path to the directory in which the alert files should be written.
final FileArgument alertDirArg =
(FileArgument) parser.getNamedArgument(ARG_NAME_ALERT_DIR);
alertDirectory = alertDirArg.getValue();
// Register as a disk space consumer since we will be writing to the
// alert directory.
registeredConsumer = serverContext.registerDiskSpaceConsumer(this);
}
/**
* Indicates whether the configuration contained in the provided argument
* parser represents a valid configuration for this extension.
*
* @param config The general configuration for this alert
* handler.
* @param parser The argument parser which has been initialized
* with the proposed configuration.
* @param unacceptableReasons A list that can be updated with reasons that
* the proposed configuration is not acceptable.
*
* @return {@code true} if the proposed configuration is acceptable, or
* {@code false} if not.
*/
@Override()
public boolean isConfigurationAcceptable(final AlertHandlerConfig config,
final ArgumentParser parser,
final List<String> unacceptableReasons)
{
// No special validation is required.
return true;
}
/**
* Attempts to apply the configuration contained in the provided argument
* parser.
*
* @param config The general configuration for this alert
* handler.
* @param parser The argument parser which has been
* initialized with the new configuration.
* @param adminActionsRequired A list that can be updated with information
* about any administrative actions that may be
* required before one or more of the
* configuration changes will be applied.
* @param messages A list that can be updated with information
* about the result of applying the new
* configuration.
*
* @return A result code that provides information about the result of
* attempting to apply the configuration change.
*/
@Override()
public ResultCode applyConfiguration(final AlertHandlerConfig config,
final ArgumentParser parser,
final List<String> adminActionsRequired,
final List<String> messages)
{
// Get the new path to the alert directory. We don't really care if it's
// the same as the directory that was already in use.
final FileArgument alertDirArg =
(FileArgument) parser.getNamedArgument(ARG_NAME_ALERT_DIR);
alertDirectory = alertDirArg.getValue();
// Cache an updated copy of the configuration.
this.config = config;
return ResultCode.SUCCESS;
}
/**
* Performs any cleanup which may be necessary when this alert handler is
* to be taken out of service.
*/
@Override()
public void finalizeAlertHandler()
{
// Deregister the disk space consumer.
if (registeredConsumer != null)
{
serverContext.deregisterDiskSpaceConsumer(registeredConsumer);
}
}
/**
* Performs any processing which may be necessary to handle the provided alert
* notification.
*
* @param alert The alert notification generated within the server.
*/
@Override()
public void handleAlert(final AlertNotification alert)
{
// The filename for the alert will be the alert ID. It will be unique, so
// we can be certain there won't be any collisions.
final File alertFile = new File(alertDirectory, alert.getAlertID());
final PrintWriter writer;
try
{
writer = new PrintWriter(alertFile);
}
catch (final Exception e)
{
serverContext.debugCaught(e);
// If we can't create the file, then we can't write anything about this
// alert. We don't want to generate an alert in response to this because
// that could create an infinite loop. The only thing we'll do is to log
// an error message.
serverContext.logMessage(LogSeverity.SEVERE_ERROR,
"The example alert handler defined in configuration entry '" +
config.getConfigObjectDN() + "' could not write file '" +
alertFile.getAbsolutePath() + "' with information about " +
"alert " + alert.toString() + ": " +
StaticUtils.getExceptionMessage(e));
return;
}
// Write information about the alert to the file.
writer.println("Alert ID: " + alert.getAlertID());
writer.println("Alert Type: " + alert.getAlertTypeName());
writer.println("Alert Severity: " + alert.getAlertSeverity().toString());
writer.println("Generated by Class: " +
alert.getAlertGeneratorClassName());
writer.println("Alert Message: " + alert.getAlertMessage());
writer.println("Alert Additional Information:");
Map<Object,Object> additionalInfo = alert.getAdditionalInformation();
for (final Object o : additionalInfo.keySet())
{
writer.printf(" %s:%s%n", o.toString(),
additionalInfo.get(o).toString());
}
writer.close();
}
/**
* Retrieves a map containing examples of configurations that may be used for
* this extension. The map key should be a list of sample arguments, and the
* corresponding value should be a description of the behavior that will be
* exhibited by the extension when used with that configuration.
*
* @return A map containing examples of configurations that may be used for
* this extension. It may be {@code null} or empty if there should
* not be any example argument sets.
*/
@Override()
public Map<List<String>,String> getExamplesArgumentSets()
{
final LinkedHashMap<List<String>,String> exampleMap =
new LinkedHashMap<List<String>,String>(1);
exampleMap.put(
Arrays.asList(ARG_NAME_ALERT_DIR + "=logs/alerts"),
"Write information about any generated alerts into the logs/alerts " +
"directory below the server root.");
return exampleMap;
}
/**
* Retrieves the name that should be used to identify this disk space
* consumer.
*
* @return The name that should be used to identify this disk space consumer.
*/
public String getDiskSpaceConsumerName()
{
return "Example Alert Handler " + config.getConfigObjectName();
}
/**
* Retrieves a list of filesystem paths in which this disk space consumer may
* store files which may consume a significant amount of space. It is
* generally recommended that the paths be directories, but they may also be
* individual files.
*
* @return A list of filesystem paths in which this disk space consumer may
* store files which may consume a significant amount of space.
*/
public List<File> getDiskSpaceConsumerPaths()
{
return Arrays.asList(alertDirectory);
}
}
