How to read and write Identified Data Serializable in Hazelcast

Question

i have a problem and the documentations and github examples doesn't provide a clear example about how to do it....

i have this class

public class KeySerializable implements IdentifiedDataSerializable{



private String claveReq;
private int id_interno_pe;
private String cod_nrbe_en;
private int num_sec_ac;
public KeySerializable(String claveReq, int id_interno_pe, String cod_nrbe_en, int num_sec_ac) {
    this.claveReq = claveReq;
    this.id_interno_pe = id_interno_pe;
    this.cod_nrbe_en = cod_nrbe_en;
    this.num_sec_ac = num_sec_ac;
}
public KeySerializable() {
}
public void writeData(ObjectDataOutput out) throws IOException {
    out.writeString(claveReq);
    out.writeInt(id_interno_pe);
    out.writeString(cod_nrbe_en);
    out.writeInt(num_sec_ac);
    
}
public void readData(ObjectDataInput in) throws IOException {
    this.claveReq = in.readString();
    this.id_interno_pe = in.readInt();
    this.cod_nrbe_en = in.readString();
    this.num_sec_ac = in.readInt();
    
}
public int getFactoryId() {
    return KeySerializableFactory.FACTORY_ID;
}
public int getClassId() {
    return KeySerializableFactory.KEY_SERIALIZABLE_TYPE;
}
@Override
public String toString() {
    return "KeySerializable [claveReq=" + claveReq + ", id_interno_pe=" + id_interno_pe + ", cod_nrbe_en="
            + cod_nrbe_en + ", num_sec_ac=" + num_sec_ac + "]";
}

}

and this class

public class ResponseSerializablePlus implements IdentifiedDataSerializable{




private int id_interno_pe;
private String cod_nrbe_en;
private int num_sec_ac;
private int statusCode;
private HashMap<String,List<String>> headers;
private byte[] content;
public ResponseSerializablePlus(int id_interno_pe, String cod_nrbe_en, int num_sec_ac, int statusCode,
        HashMap<String, List<String>> headers, byte[] content) {
    this.id_interno_pe = id_interno_pe;
    this.cod_nrbe_en = cod_nrbe_en;
    this.num_sec_ac = num_sec_ac;
    this.statusCode = statusCode;
    this.headers = headers;
    this.content = content;
}
public ResponseSerializablePlus() {
}
public void writeData(ObjectDataOutput out) throws IOException {
    out.writeInt(id_interno_pe);
    out.writeString(cod_nrbe_en);
    out.writeInt(num_sec_ac);
    out.write(statusCode);
    out.writeObject(headers);
    out.writeByteArray(content);
    
}
public void readData(ObjectDataInput in) throws IOException {
    this.id_interno_pe = in.readInt();
    this.cod_nrbe_en = in.readString();
    this.num_sec_ac = in.readInt();
    this.statusCode = in.readInt();
    this.headers = in.readObject();
    this.content = in.readByteArray();
    
}
public int getFactoryId() {
    return ResponseSerializablePlusFactory.FACTORY_ID;
}
public int getClassId() {
    return ResponseSerializablePlusFactory.RESPONSE_SERIALIZABLE_PLUS_CLASS;
}
@Override
public String toString() {
    return "ResponseSerializablePlus [id_interno_pe=" + id_interno_pe + ", cod_nrbe_en=" + cod_nrbe_en
            + ", num_sec_ac=" + num_sec_ac + ", statusCode=" + statusCode + ", headers=" + headers + ", content="
            + Arrays.toString(content) + "]";
}

and this other class

public class ResponseSerializable implements IdentifiedDataSerializable{



private int statusCode;
private HashMap<String,List<String>> headers;
private byte[] content;
public ResponseSerializable(int statusCode, HashMap<String, List<String>> headers, byte[] content) {
    this.statusCode = statusCode;
    this.headers = headers;
    this.content = content;
}
public ResponseSerializable() {
}

public void writeData(ObjectDataOutput out) throws IOException {
    out.write(statusCode);
    out.writeObject(headers);
    out.writeByteArray(content);
    
}

public void readData(ObjectDataInput in) throws IOException {
    this.statusCode = in.readInt();
    this.headers = in.readObject();
    this.content = in.readByteArray();
    
}
public int getFactoryId() {
    
    return ResponseSerializableFactory.FACTORY_ID;
}
public int getClassId() {
    return ResponseSerializableFactory.RESPONSE_TYPE;
}
@Override
public String toString() {
    return "ResponseSerializable [statusCode=" + statusCode + ", headers=" + headers + ", content="
            + Arrays.toString(content) + "]";
}

}

and the factory it's always the same but with different classes

public class KeySerializableFactory implements DataSerializableFactory{

public static final int FACTORY_ID = 1;

public static final int KEY_SERIALIZABLE_TYPE = 1;

public IdentifiedDataSerializable create(int typeId) {
    if ( typeId == KEY_SERIALIZABLE_TYPE ) {
        return new KeySerializable();
    } else {
        return null;
    }
}

}

and im always having this bunch errors

the documentation and the github examples from hazelcast doesn't provide a good example about how to use the getters and setters and i don't understand what to do here to write or read an object

any hint? can you help me?

Answer 1

You shouldn't be calling readData or writeData yourself. These methods are called by Hazelcast internally when the data is about to be serialized/deserialized.

On your side, you should only register the data serializable factories you have created to the Hazelcast.

Then, upon receiving an instance of a class that implements IdentifiedDataSerializable and has a factory registered for it, Hazelcast will call the methods I mentioned above in appropriate places and return you the object read.

From the code sample you shared, you need to drop the line starting with newResponse.writeData(..., and everything should be working, assuming you did the factory registration.

Also, please fix your ResponseSerializablePlus and ResponseSerializable classes: You need to use writeInt method to write the statusCode field. The readData and writeData methods should be consistent with each other.