WebClients
can
be
configured
in
Spring
to
handle
the
failover
in
case
any
of
the
webservice
connection
fails
to
respond
due
to
network
or
server
failure
or
due
to
any
other
reason.
In
order
to
handle
such
issues
Apache
CXF
provides
Sequential
and
Random
strategies,
which
are
supported
and
implementers
can
develop
more
sophisticated
failover
features
by
retrieving
alternate
addresses.
The
above
could
be
achieved
by
doing
the
following
configurations
in
spring-servlet.xml
(Spring
Web
Context
Configuration
file)
or
whatever
else
you
call
it.
Spring-servlet.xml(
failover
configurations
only)
____________________________________________________________________________
<?xml
version="1.0"
encoding="UTF-8"?>
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:cache="http://www.springframework.org/schema/cache"
xmlns:cxf="http://cxf.apache.org/core"
xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="http://cxf.apache.org/core
http://cxf.apache.org/schemas/core.xsd
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.springframework.org/schema/cache
http://www.springframework.org/schema/cache/spring-cache.xsd
http://www.springframework.org/schema/util
http://www.springframework.org/schema/util/spring-util-2.0.xsd
"
>
<!--
begin: Fail over configurations -->
<util:list
id="alternateSerAddresses"
list-class="java.util.concurrent.CopyOnWriteArrayList">
<value>http://hostname:port/servie-location-1</value>
<value>http://hostname:port/servie-location-2</value>
<value>http://hostname:port/servie-location-3</value>
</util:list>
<bean
id="serviceClientFactory"
class="org.apache.cxf.jaxws.JaxWsProxyFactoryBean">
<property
name="serviceClass"
value="com.soaptopupsuite.EndPointInterface"/>
<property
name="address"
value="http://hostname:port/service-default-loc"/>
<property
name="username"
value="service-username"/>
<property
name="password"
value="service-password"/>
<property
name="features">
<util:list>
<bean
class="org.apache.cxf.clustering.FailoverFeature">
<property
name="strategy">
<bean
class="org.apache.cxf.clustering.SequentialStrategy">
<property
name="alternateAddresses"
ref="alternateSerAddresses"/>
</bean>
</property>
</bean>
</util:list>
</property>
</bean>
<bean
id="serviceClient"
class="com.soaptopupsuite.EndPointInterface"
factory- bean="serviceClientFactory"
factory-method="create"/>
<bean
id="servicePort"
class="com.swaraj.client.WsClient">
<property
name="port"
ref="serviceClient"
/>
</bean>
<!--
end: Fail over configurations -->
</beans>
Here,
the
client
factory
does
not
itself
defines
the
address
attribute.
It
uses
that
alternateSerAddresses
list
exclusively
throughout
all
the
invocations
and
primary
address
exists
as
default
location.
SequentialStrategy
will
use
one
endpoint
after
another
providing
nice
round
robin
implementation
(RandomStrategy
is
available
as
well,
where
an
end
point
is
picked
up
randomly).
Also
in
this
configuration
we
will
get
failover
– if
any
endpoint
fails,
all
endpoints
starting
from
the
default
one
will
be
examined
(except
the
one
that
has
just
failed).
Reference
Java
Code (Spring 3.1) :
package
com.swaraj.client;
@Service
public
class
WsClient
{
/*
list of
instance variable*/
//
web
service
location
private
EndPointInterface
port;
//
setter
injection
for
EndPointInterface
public
void
setPort(EndPointInterface
port)
{
this.port
=
port;
}
//
Invoking
web
service
method
on
EndPointInterface
port.
public
String
webSerMethodCall(){
return
port.testCall();
}
}
