Unable to persist CFC to App scope if invoked by Webservice call (With workaround)
I have come across the following issue when attempting to persist a CFC to the Coldfusion Application scope, when the the CFC method had been invoked remotely.
If I take the following cfc:
app_persit.cfc
<cffunction name="init" output="true">
<cfif not isdefined("application.persistedobject")>
<cfset _initialiseObject()>
<cfset variables.persitedvalue = 54321>
<cfelse>
<cfset variables.persitedvalue = 0>
</cfif>
<cfreturn application.persistedobject>
</cffunction>
<cffunction name="remotetest" output="false" access="remote" returntype="numeric">
<cfset var localObject = init()>
<cfreturn localObject.returnPersistedValue()>
</cffunction>
<cffunction name="_initialiseObject" output="true">
<cfset variables.persitedvalue = 12345>
<cfset application.persistedobject = this>
</cffunction>
<cffunction name="returnPersistedValue" output="false" returntype="numeric">
<cfreturn variables.persitedvalue>
</cffunction>
</cfcomponent>
and call it with the following CFML code:
test_app_persit.cfm
<cfset x = persistedobject_ref.remotetest()>
<cfdump var="#x#">
The object would get created, and persisted to application scope correctly - with all subsequent calls to the remotetest() function using the object which had been persisted to Application scope.
If I then try to call this method as a web service (after first clearing the application scope) as follows:
<cfset x = persistedobject_ref.remotetest()>
<cfdump var="#x#">
The first time I execute the code, it runs as expected.
On all subsequent requests, I would get the following error:
Here is the fault returned when invoking the web service operation:
AxisFault
faultCode: {http://schemas.xmlsoap.org/soap/envelope/}Server.userException
faultSubcode:
faultString: coldfusion.xml.rpc.CFCInvocationException:
[java.lang.NullPointerException : null]
faultActor:
faultNode:
faultDetail:
{http://xml.apache.org/axis/}stackTrace:coldfusion.xml.rpc.CFCInvocationException: [java.lang.NullPointerException : null]
at coldfusion.xml.rpc.CFComponentSkeleton.__createCFCInvocationException(CFComponentSkeleton.java:714)
at coldfusion.xml.rpc.CFComponentSkeleton.__invoke(CFComponentSkeleton.java:660)
at cf7.test.cfcs.app_persist.remotetest(C:\sites\cf7\test\cfcs\app_persist.cfc)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.apache.axis.providers.java.RPCProvider.invokeMethod(RPCProvider.java:388)
at org.apac...
On further investigation, it appears that although application.persistedobject was defined, it was a null reference - i.e. the object to which the variable had pointed no longer exists.
So it appears that it is not possible to persist a CFC to the application scope a method is executed remotely. (Is this a bug? - I expected the same behaviour from a remote invocation as from a local invocation...)
As a work around (and probably better practice anyway) I created the following wrapper CFC:
app_persist_wrapper.cfc
<cffunction name="remotetest" output="true" access="remote" returntype="numeric">
<cfset var localObject = "">
<cfset var persistedobject_ref = createobject("component","app_persist")>
<cfset localObject = persistedobject_ref.init()>
<cfreturn localObject.returnPersistedValue()>
</cffunction>
</cfcomponent>
When I invoked this as follows:
<cfset x = persistedobject_ref.remotetest()>
<cfdump var="#x#">
This works correctly - the original object is persisted to application scope as intended, and retrieved from there on subsequent requests.
(Took me over a day to figure out what was happening here as part of testing a much more complex application - hopefully this will save someone else some time :)
well i've not tried persisting my WS before.
i think i'll try this out