org.apache.tools.ant.taskdefs.condition
Class IsReachable

java.lang.Object
  org.apache.tools.ant.ProjectComponent
      org.apache.tools.ant.taskdefs.condition.IsReachable

All Implemented Interfaces:

java.lang.Cloneable, Condition

public class IsReachable
extends ProjectComponent
implements Condition

Test for a host being reachable using ICMP "ping" packets & echo operations. Ping packets are very reliable for assessing reachability in a LAN or WAN, but they do not get through any well-configured firewall. Echo (port 7) may.

This condition turns unknown host exceptions into false conditions. This is because on a laptop, DNS is one of the first services lost when the network goes; you are implicitly offline.

If a URL is supplied instead of a host, the hostname is extracted and used in the test--all other parts of the URL are discarded.

The test may not work through firewalls; that is, something may be reachable using a protocol such as HTTP, while the lower level ICMP packets get dropped on the floor. Similarly, a host may be detected as reachable with ICMP, but not reachable on other ports (i.e. port 80), because of firewalls.

Requires Java 5+ to work properly. On Java 1.4, if a hostname can be resolved, the destination is assumed to be reachable.

Since:

Ant 1.7

Field Summary

static int	DEFAULT_TIMEOUT The default timeout.
static java.lang.String	ERROR_BAD_TIMEOUT Error when invalid timeout value is defined
static java.lang.String	ERROR_BAD_URL Error message when an invalid url is used.
static java.lang.String	ERROR_BOTH_TARGETS Error message when url and host are specified.
static java.lang.String	ERROR_NO_HOST_IN_URL Error message when no hostname in url.
static java.lang.String	ERROR_NO_HOSTNAME Error when no hostname is defined
static java.lang.String	ERROR_ON_NETWORK Network error message is seen.
static java.lang.String	METHOD_NAME The method name to look for in InetAddress
static java.lang.String	MSG_NO_REACHABLE_TEST Error message when no reachably test avail.

Fields inherited from class org.apache.tools.ant.ProjectComponent

description, location, project

Constructor Summary

IsReachable()

Method Summary

boolean	eval() Evaluate the condition.
void	setHost(java.lang.String host) Set the host to ping.
void	setTimeout(int timeout) Set the timeout for the reachability test in seconds.
void	setUrl(java.lang.String url) Set the URL from which to extract the hostname.

Methods inherited from class org.apache.tools.ant.ProjectComponent

clone, getDescription, getLocation, getProject, log, log, setDescription, setLocation, setProject

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_TIMEOUT

public static final int DEFAULT_TIMEOUT

The default timeout.

See Also:

Constant Field Values

ERROR_NO_HOSTNAME

public static final java.lang.String ERROR_NO_HOSTNAME

Error when no hostname is defined

See Also:

Constant Field Values

ERROR_BAD_TIMEOUT

public static final java.lang.String ERROR_BAD_TIMEOUT

Error when invalid timeout value is defined

See Also:

Constant Field Values

ERROR_ON_NETWORK

public static final java.lang.String ERROR_ON_NETWORK

Network error message is seen.

See Also:

Constant Field Values

ERROR_BOTH_TARGETS

public static final java.lang.String ERROR_BOTH_TARGETS

Error message when url and host are specified.

See Also:

Constant Field Values

MSG_NO_REACHABLE_TEST

public static final java.lang.String MSG_NO_REACHABLE_TEST

Error message when no reachably test avail.

See Also:

Constant Field Values

ERROR_BAD_URL

public static final java.lang.String ERROR_BAD_URL

Error message when an invalid url is used.

See Also:

Constant Field Values

ERROR_NO_HOST_IN_URL

public static final java.lang.String ERROR_NO_HOST_IN_URL

Error message when no hostname in url.

See Also:

Constant Field Values

METHOD_NAME

public static final java.lang.String METHOD_NAME

The method name to look for in InetAddress

See Also:

Constant Field Values

Constructor Detail

IsReachable

public IsReachable()

Method Detail

setHost

public void setHost(java.lang.String host)

Set the host to ping.

Parameters:

host - the host to ping.

setUrl

public void setUrl(java.lang.String url)

Set the URL from which to extract the hostname.

Parameters:

url - a URL object.

setTimeout

public void setTimeout(int timeout)

Set the timeout for the reachability test in seconds.

Parameters:

timeout - the timeout in seconds.

eval

public boolean eval()
             throws BuildException

Evaluate the condition.

Specified by:

eval in interface Condition

Returns:

true if the condition is true.

Throws:

BuildException - if an error occurs