Internal Server Error (circular reference detected while serializing: ....

Question

Hello Folks -
I am trying to implement both ManyToMany and OneToMany relationships in J2EE EJB3.0.
My application client has no problems, but when I expose my session bean methods as WebServices, I constantly run into this circular reference error.
My example tables are simple:
CREATE TABLE CLUB
ID NUMBER NOT NULL,
NAME VARCHAR2(100 BYTE) NOT NULL,
CITY VARCHAR2(100 BYTE) NOT NULL,
COUNTRY VARCHAR2(100 BYTE) NOT NULL
TABLESPACE USERS
PCTUSED 0
PCTFREE 10
INITRANS 1
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
BUFFER_POOL DEFAULT
CREATE UNIQUE INDEX CLUB_PK ON CLUB
(ID)
TABLESPACE USERS
PCTFREE 10
INITRANS 2
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
BUFFER_POOL DEFAULT
CREATE UNIQUE INDEX CLUB_UK1 ON CLUB
(NAME, COUNTRY)
TABLESPACE USERS
PCTFREE 10
INITRANS 2
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
BUFFER_POOL DEFAULT
ALTER TABLE CLUB ADD (
CONSTRAINT CLUB_PK
PRIMARY KEY
(ID)
USING INDEX
TABLESPACE USERS
PCTFREE 10
INITRANS 2
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
ALTER TABLE CLUB ADD (
CONSTRAINT CLUB_UK1
UNIQUE (NAME, COUNTRY)
USING INDEX
TABLESPACE USERS
PCTFREE 10
INITRANS 2
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
CREATE TABLE CONTRACTPERIOD
ID NUMBER NOT NULL,
PYR_ID NUMBER NOT NULL,
CUB_ID NUMBER NOT NULL,
START_DATE DATE NOT NULL,
END_DATE DATE
TABLESPACE USERS
PCTUSED 0
PCTFREE 10
INITRANS 1
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
BUFFER_POOL DEFAULT
CREATE UNIQUE INDEX CONTRACTPERIOD_PK ON CONTRACTPERIOD
(ID)
TABLESPACE USERS
PCTFREE 10
INITRANS 2
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
BUFFER_POOL DEFAULT
ALTER TABLE CONTRACTPERIOD ADD (
CONSTRAINT CONTRACTPERIOD_PK
PRIMARY KEY
(ID)
USING INDEX
TABLESPACE USERS
PCTFREE 10
INITRANS 2
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
ALTER TABLE CONTRACTPERIOD ADD (
CONSTRAINT CONTRACTPERIOD_FK
FOREIGN KEY (PYR_ID)
REFERENCES PLAYER (ID)
ON DELETE CASCADE);
ALTER TABLE CONTRACTPERIOD ADD (
CONSTRAINT CONTRACTPERIOD_FK2
FOREIGN KEY (CUB_ID)
REFERENCES CLUB (ID)
ON DELETE CASCADE);
CREATE TABLE PLAYER
ID NUMBER NOT NULL,
FIRSTNAME VARCHAR2(30 BYTE) NOT NULL,
LASTNAME VARCHAR2(30 BYTE) NOT NULL,
NATIONALITY VARCHAR2(30 BYTE) NOT NULL,
BIRTHDATE DATE NOT NULL
TABLESPACE USERS
PCTUSED 0
PCTFREE 10
INITRANS 1
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
BUFFER_POOL DEFAULT
CREATE UNIQUE INDEX PLAYERS_PK ON PLAYER
(ID)
TABLESPACE USERS
PCTFREE 10
INITRANS 2
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
BUFFER_POOL DEFAULT
ALTER TABLE PLAYER ADD (
CONSTRAINT PLAYERS_PK
PRIMARY KEY
(ID)
USING INDEX
TABLESPACE USERS
PCTFREE 10
INITRANS 2
MAXTRANS 255
STORAGE (
INITIAL 64K
MINEXTENTS 1
MAXEXTENTS 2147483645
PCTINCREASE 0
Also the Stateless session bean is simple:
package demo;
import java.util.Collection;
import java.util.List;
import javax.ejb.Stateless;
import javax.jws.WebService;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.Query;
@Stateless
@WebService
public class JavaServiceFacade {
private EntityManagerFactory emf = Persistence.createEntityManagerFactory("demo-1");
public JavaServiceFacade() {
public static void main(String [] args) {
final JavaServiceFacade javaServiceFacade = new JavaServiceFacade();
// TODO: Call methods on javaServiceFacade here...
Collection<Player> playerCollection = javaServiceFacade.queryPlayerFindAll();
for (Player player : playerCollection){
System.out.println(player.getFirstname()+" "+player.getLastname()+"\n");
Collection<Club> clubCollection = (Collection<Club>)javaServiceFacade.queryClubFindAll();
for (Club club : clubCollection){
System.out.println(club.getName()+"\n");
List<Contractperiod> contractperiodList= player.getContractperiodList();
for (Contractperiod contractperiod : contractperiodList){
System.out.println("contracts: "+ contractperiod.getClub().getName() + ": from: "
contractperiod.getStartDate()" to: " contractperiod.getEndDate() "\n");
private EntityManager getEntityManager() {
return emf.createEntityManager();
public Object mergeEntity(Object entity) {
final EntityManager em = getEntityManager();
try {
final EntityTransaction et = em.getTransaction();
try {
et.begin();
em.merge(entity);
et.commit();
} finally {
if (et != null && et.isActive()) {
entity = null;
et.rollback();
} finally {
if (em != null && em.isOpen()) {
em.close();
return entity;
public Object persistEntity(Object entity) {
final EntityManager em = getEntityManager();
try {
final EntityTransaction et = em.getTransaction();
try {
et.begin();
em.persist(entity);
et.commit();
} finally {
if (et != null && et.isActive()) {
entity = null;
et.rollback();
} finally {
if (em != null && em.isOpen()) {
em.close();
return entity;
/** <code>select o from Club o</code> */
public List<Club> queryClubFindAll() {
Query query = getEntityManager().createNamedQuery("Club.findAll");
return (List<Club>) query.getResultList();
public void removeClub(Club club) {
final EntityManager em = getEntityManager();
try {
final EntityTransaction et = em.getTransaction();
try {
et.begin();
club = em.find(Club.class, club.getId());
et.commit();
} finally {
if (et != null && et.isActive()) {
et.rollback();
} finally {
if (em != null && em.isOpen()) {
em.close();
/** <code>select o from Contractperiod o</code> */
public List<Contractperiod> queryContractperiodFindAll() {
Query query = getEntityManager().createNamedQuery("Contractperiod.findAll");
return (List<Contractperiod>) query.getResultList();
public void removeContractperiod(Contractperiod contractperiod) {
final EntityManager em = getEntityManager();
try {
final EntityTransaction et = em.getTransaction();
try {
et.begin();
contractperiod = em.find(Contractperiod.class, contractperiod.getId());
et.commit();
} finally {
if (et != null && et.isActive()) {
et.rollback();
} finally {
if (em != null && em.isOpen()) {
em.close();
/** <code>select o from Player o</code> */
public List<Player> queryPlayerFindAll() {
Query query = getEntityManager().createNamedQuery("Player.findAll");
return (List<Player>) query.getResultList();
public void removePlayer(Player player) {
final EntityManager em = getEntityManager();
try {
final EntityTransaction et = em.getTransaction();
try {
et.begin();
player = em.find(Player.class, player.getId());
et.commit();
} finally {
if (et != null && et.isActive()) {
et.rollback();
} finally {
if (em != null && em.isOpen()) {
em.close();
public void removeClub(Club player) {
final EntityManager em = getEntityManager();
try {
final EntityTransaction et = em.getTransaction();
try {
et.begin();
player = em.find(Player.class, player.getId());
et.commit();
} finally {
if (et != null && et.isActive()) {
et.rollback();
} finally {
if (em != null && em.isOpen()) {
em.close();
(A few commented lines, as I tried both OneToMany and ManyToMany...)
my Webservice result, after deploying to OC4J Standalone, is always the same:
Entity Beans:
package demo;
import java.io.Serializable;
import java.util.Collection;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.NamedQuery;
import javax.persistence.OneToMany;
@Entity
@NamedQuery(name = "Club.findAll", query = "select o from Club o")
public class Club implements Serializable {
@Column(nullable = false)
private String city;
@Column(nullable = false)
private String country;
@Id
@Column(nullable = false)
private Long id;
@Column(nullable = false)
private String name;
@ManyToMany(mappedBy = "clubCollection",cascade={CascadeType.PERSIST})
private Collection<Player> playerCollection;
public Club() {
public String getCity() {
return city;
public void setCity(String city) {
this.city = city;
public String getCountry() {
return country;
public void setCountry(String country) {
this.country = country;
public Long getId() {
return id;
public void setId(Long id) {
this.id = id;
public String getName() {
return name;
public void setName(String name) {
this.name = name;
public Collection<Player> getPlayerCollection() {
return playerCollection;
public void setPlayerCollection(Collection<Player> playerCollection) {
this.playerCollection = playerCollection;
public Contractperiod addContractperiod(Contractperiod contractperiod) {
getContractperiodList().add(contractperiod);
contractperiod.setClub(this);
return contractperiod;
public Contractperiod removeContractperiod(Contractperiod contractperiod) {
getContractperiodList().remove(contractperiod);
contractperiod.setClub(null);
return contractperiod;
package demo;
import java.io.Serializable;
import java.sql.Timestamp;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.NamedQuery;
@Entity
@NamedQuery(name = "Contractperiod.findAll",
query = "select o from Contractperiod o")
public class Contractperiod implements Serializable {
@Column(name="END_DATE")
private Timestamp endDate;
@Id
@Column(nullable = false)
private Long id;
@Column(name="START_DATE", nullable = false)
private Timestamp startDate;
@ManyToOne
@JoinColumn(name = "PYR_ID", referencedColumnName = "ID")
private Player player;
@ManyToOne
@JoinColumn(name = "CUB_ID", referencedColumnName = "ID")
private Club club;
public Contractperiod() {
public Timestamp getEndDate() {
return endDate;
public void setEndDate(Timestamp endDate) {
this.endDate = endDate;
public Long getId() {
return id;
public void setId(Long id) {
this.id = id;
public Timestamp getStartDate() {
return startDate;
public void setStartDate(Timestamp startDate) {
this.startDate = startDate;
public Player getPlayer() {
return player;
public void setPlayer(Player player) {
this.player = player;
public Club getClub() {
return club;
public void setClub(Club club) {
this.club = club;
package demo;
import java.io.Serializable;
import java.sql.Timestamp;
import java.util.Collection;
import java.util.List;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.NamedQuery;
import javax.persistence.OneToMany;
@Entity
@NamedQuery(name = "Player.findAll", query = "select o from Player o")
public class Player implements Serializable {
@Column(nullable = false)
private Timestamp birthdate;
@Column(nullable = false)
private String firstname;
@Id
@Column(nullable = false)
private Long id;
@Column(nullable = false)
private String lastname;
@Column(nullable = false)
private String nationality;
@ManyToMany
@JoinTable(name="CONTRACTPERIOD",
joinColumns=@JoinColumn(name="PYR_ID"),
inverseJoinColumns=@JoinColumn(name="CUB_ID"))
private Collection<Club> clubCollection;
public Player() {
public Timestamp getBirthdate() {
return birthdate;
public void setBirthdate(Timestamp birthdate) {
this.birthdate = birthdate;
public String getFirstname() {
return firstname;
public void setFirstname(String firstname) {
this.firstname = firstname;
public Long getId() {
return id;
public void setId(Long id) {
this.id = id;
public String getLastname() {
return lastname;
public void setLastname(String lastname) {
this.lastname = lastname;
public String getNationality() {
return nationality;
public void setNationality(String nationality) {
this.nationality = nationality;
public Collection<Club> getClubCollection() {
return clubCollection;
public void setClubCollection(Collection<Club> clubCollection) {
this.clubCollection = clubCollection;
public Contractperiod addContractperiod(Contractperiod contractperiod) {
getContractperiodList().add(contractperiod);
contractperiod.setPlayer(this);
return contractperiod;
public Contractperiod removeContractperiod(Contractperiod contractperiod) {
getContractperiodList().remove(contractperiod);
contractperiod.setPlayer(null);
return contractperiod;
<env:Envelope
xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:ns0="http://demo/">
<env:Body>
<env:Fault>
<faultcode>env:Server</faultcode>
<faultstring>Internal Server Error (circular reference detected while serializing: demo.Contractperiod)</faultstring>
</env:Fault>
</env:Body>
</env:Envelope>
Anyone else run into this Troll?
All suggestions(almost all) received with thanks.
Regards,
Charles
Some strange error messages in Diagnostic Logs:
Log Message: September 18, 2006 3:58:02 PM CEST
     Component Name          OC4J          Component ID          j2ee
     Host Network Address          192.168.1.69          Message Level          1
     Module ID          home_ejb.transaction          User ID          Charles
     Execution Context ID          192.168.1.69:35920:1158587882221:405          Execution Context Sequence          0
     Host Name          vmware          Message ID          J2EE EJB-08006
     Thread ID          44          Message Type          Error
     J2EE Application Module          OraPorterAPIdeploy          J2EE Application          OraPorterAPIdeploy
     Web Service Port          JavaServiceFacade          Web Service Name          JavaServiceFacadeService
Message Text
[JavaServiceFacade:public java.util.List demo.JavaServiceFacade.queryClubFindAll()] exception occurred during method invocation: oracle.
Supplemental Text
oracle.oc4j.rmi.OracleRemoteException: java.lang.IllegalStateException: ClassLoader "OraPorterAPIdeploy.root:0.0.0" (from <application>
in /C:/Oracle/oc4j/j2ee/home/applications/OraPorterAPIdeploy/): This loader has been closed and should not be in use.
Nested exception is:
java.lang.IllegalStateException: ClassLoader "OraPorterAPIdeploy.root:0.0.0" (from <application> in /C:/Oracle/oc4j/j2ee/home/applications/OraPorterAPIdeploy/):
This loader has been closed and should not be in use.
........This loader has been
closed and should not be in use.; nested exception is:
java.lang.IllegalStateException: ClassLoader
Message was edited by:
promise
Message was edited by:
promise

Answer 1

Hei Guys -
I see that the ClassLoader exceptions are known, and are "to be ignored".
I left a reference to them, in case they play into our problems anyway.....
"java.lang.IllegalStateException: ClassLoader" - known harmless bug... ?
Best Regards,
Charles