I have a model class which I want to use in different projects. I am not sure where I am doing wrong, if anyone can catch my error.

Project fsmodel - Consists only model class. Eg: AdhocAlbum.java (attached). Maven dependencies

Included this project into another project FSWebService

Compiled Successfully. But throwing error at runtime.

SUCCESSFUL PROPERTIES LOAD
Nov 4, 2013 5:43:34 PM org.apache.catalina.core.ApplicationContext log
INFO: Initializing Spring FrameworkServlet 'fsrest'
Nov 4, 2013 5:43:36 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-bio-8080"]
Nov 4, 2013 5:43:36 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
Nov 4, 2013 5:43:36 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 9156 ms
Nov 4, 2013 5:43:36 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [fsrest] in context with path [/pkoapi] threw exception [Request processing failed; nested exception is org.springframework.dao.InvalidDataAccessApiUsageException: Unknown entity: fsmodel.model.adhoc.AdhocAlbum; nested exception is java.lang.IllegalArgumentException: Unknown entity: fsmodel.model.adhoc.AdhocAlbum] with root cause
org.hibernate.MappingException: Unknown entity: fsmodel.model.adhoc.AdhocAlbum
    at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:1192)
    at org.hibernate.internal.SessionImpl.locateEntityPersister(SessionImpl.java:2436)
    at org.hibernate.internal.SessionImpl.access$2100(SessionImpl.java:172)
    at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.<init>(SessionImpl.java:2378)
    at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.<init>(SessionImpl.java:2382)
    at org.hibernate.internal.SessionImpl$IdentifierLoadAccessImpl.<init>(SessionImpl.java:2369)
    at org.hibernate.internal.SessionImpl.byId(SessionImpl.java:1052)
    at org.hibernate.internal.SessionImpl.get(SessionImpl.java:975)
    at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:807)
    at org.hibernate.ejb.AbstractEntityManagerImpl.find(AbstractEntityManagerImpl.java:781)
    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:597)
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:365)
    at com.sun.proxy.$Proxy18.find(Unknown Source)
    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:597)
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:240)
    at com.sun.proxy.$Proxy18.find(Unknown Source)
    at fsrest.model.adhoc.dao.jpa.AdhocAlbumDaoImpl.getAdhocAlbumById(AdhocAlbumDaoImpl.java:24)
    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:597)
    at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:319)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:155)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
    at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)
    at com.sun.proxy.$Proxy19.getAdhocAlbumById(Unknown Source)
    at fsrest.webapp.controller.core.HomeController.index(HomeController.java:23)

I don't have any Entity Classes in my FSWebService Project. All classes are in FSModel Project.

Example do make  sense though  I haven't tried it yet. I will definitely implement it, but just wondering if I end up having 100 classes then I have to explicitly include it in persistence.xml

Thanks for the reply, I may ask few things to proceed in right direction