src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/constants/DmStatus.java

+package gov.anl.aps.dm.common.constants;
+
+/**
+ * DM status codes.
+ */
+public class DmStatus {
+
+    public static final int DM_OK = 0;
+    public static final int DM_ERROR = 1;
+    public static final int DM_INTERNAL_ERROR = 2;
+    public static final int DM_COMMUNICATION_ERROR = 3;
+    public static final int DM_CONFIGURATION_ERROR = 4;
+    public static final int DM_AUTHORIZATION_ERROR = 5;
+    public static final int DM_AUTHENTICATION_ERROR = 6;
+    public static final int DM_DB_ERROR = 7;
+    public static final int DM_URL_ERROR = 8;
+    public static final int DM_TIMEOUT_ERROR = 9;
+    public static final int DM_INVALID_ARGUMENT = 10;
+    public static final int DM_INVALID_REQUEST = 11;
+    public static final int DM_INVALID_SESSION = 12;
+    public static final int DM_COMMAND_FAILED = 13;
+    public static final int DM_OBJECT_NOT_FOUND = 14;
+    public static final int DM_OBJECT_ALREADY_EXISTS = 15;
+    public static final int DM_INVALID_OBJECT_STATE = 16;
+    public static final int DM_FILE_PROCESSING_ERROR = 17;
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/AuthenticationError.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Authentication error exception.
+ */
+public class AuthenticationError extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public AuthenticationError() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public AuthenticationError(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public AuthenticationError(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public AuthenticationError(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_AUTHENTICATION_ERROR;
+    }    
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/AuthorizationError.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Authorization error exception.
+ */
+public class AuthorizationError extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public AuthorizationError() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public AuthorizationError(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public AuthorizationError(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public AuthorizationError(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_AUTHORIZATION_ERROR;
+    }      
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/CommunicationError.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Communication error exception.
+ */
+public class CommunicationError extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public CommunicationError() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public CommunicationError(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public CommunicationError(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public CommunicationError(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_COMMUNICATION_ERROR;
+    }     
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/ConfigurationError.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Configuration error exception.
+ */
+public class ConfigurationError extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public ConfigurationError() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public ConfigurationError(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor sing throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public ConfigurationError(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public ConfigurationError(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_CONFIGURATION_ERROR;
+    }    
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/DbError.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * DB error exception.
+ */
+public class DbError extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public DbError() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public DbError(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public DbError(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public DbError(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_DB_ERROR;
+    }    
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/DmException.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Generic DM exception, used as base class for all DM exceptions.
+ */
+public class DmException extends Exception {
+
+    /**
+     * Exception keys.
+     */
+    public static final String SIGNATURE_KEY = "__dm_exception__";
+    public static final String TYPE_KEY = "type";
+    public static final String CODE_KEY = "code";
+    public static final String ARGS_KEY = "args";
+
+    private String error = null;
+
+    /**
+     * Default constructor.
+     */
+    public DmException() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public DmException(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public DmException(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public DmException(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    public int getErrorCode() {
+        return DmStatus.DM_ERROR;
+    }
+
+    public void setErrorMessage(String error) {
+        this.error = error;
+    }
+
+    public String getErrorMessage() {
+        if (error != null) {
+            return error;
+        }
+        return super.getMessage();
+    }
+
+    /**
+     * Convert exception to string, overriding string output if error message is
+     * set.
+     *
+     * @return exception string
+     */
+    @Override
+    public String toString() {
+        if (error != null) {
+            return error;
+        } else {
+            return super.toString();
+        }
+    }
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/DmExceptionFactory.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+import org.apache.log4j.Logger;
+
+/**
+ * DM exception factory class.
+ *
+ */
+public class DmExceptionFactory {
+
+    private static final Logger logger
+            = Logger.getLogger(DmExceptionFactory.class.getName());
+
+    /**
+     * Generate DM exception.
+     *
+     * @param type exception type
+     * @param code exception code
+     * @param error exception error message
+     * @return generated DM exception
+     */
+    public static DmException generateDmException(String type, int code, String error) {
+        DmException exc = new DmException();
+        try {
+            String fullType = "gov.anl.aps.dm.common.exceptions." + type;
+            // Having trouble getting code below to work in all cases, so
+            // use code for now.
+            // exc = (DmException) Class.forName(fullType).newInstance();
+            switch (code) {
+
+                case DmStatus.DM_AUTHORIZATION_ERROR:
+                    exc = new AuthorizationError();
+                    break;
+                case DmStatus.DM_COMMUNICATION_ERROR:
+                    exc = new CommunicationError();
+                    break;
+                case DmStatus.DM_CONFIGURATION_ERROR:
+                    exc = new ConfigurationError();
+                    break;
+                case DmStatus.DM_INTERNAL_ERROR:
+                    exc = new InternalError();
+                    break;
+               case DmStatus.DM_DB_ERROR:
+                    exc = new DbError();
+                    break;
+                case DmStatus.DM_INVALID_ARGUMENT:
+                    exc = new InvalidArgument();
+                    break;
+                case DmStatus.DM_INVALID_REQUEST:
+                    exc = new InvalidRequest();
+                    break;
+                case DmStatus.DM_INVALID_SESSION:
+                    exc = new InvalidSession();
+                    break;
+                case DmStatus.DM_OBJECT_ALREADY_EXISTS:
+                    exc = new ObjectAlreadyExists();
+                    break;
+                case DmStatus.DM_OBJECT_NOT_FOUND:
+                    exc = new ObjectNotFound();
+                    break;
+                case DmStatus.DM_INVALID_OBJECT_STATE:
+                    exc = new InvalidObjectState();
+                    break;
+                case DmStatus.DM_TIMEOUT_ERROR:
+                    exc = new TimeoutError();
+                    break;                    
+                default:
+                    exc = (DmException) Class.forName(fullType).newInstance();
+            }
+        } catch (ClassNotFoundException | IllegalAccessException | InstantiationException ex) {
+            String err = "Cannot generate exception of type " + type + ": " + ex;
+            logger.error(err);
+        }
+        exc.setErrorMessage(error);
+        return exc;
+    }
+
+    /**
+     * Throw DM exception.
+     *
+     * @param type exception type
+     * @param code exception code
+     * @param error exception error message
+     * @throws DmException generated DM exception whenever this method is
+     * called
+     */
+    public static void throwDmException(String type, int code, String error) throws DmException {
+        DmException exc = generateDmException(type, code, error);
+        throw exc;
+    }
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/InternalError.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Internal error exception.
+ */
+public class InternalError extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public InternalError() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public InternalError(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public InternalError(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public InternalError(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+    
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_INTERNAL_ERROR;
+    }
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/InvalidArgument.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Invalid argument exception.
+ */
+public class InvalidArgument extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public InvalidArgument() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public InvalidArgument(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public InvalidArgument(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public InvalidArgument(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_INVALID_ARGUMENT;
+    }    
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/InvalidObjectState.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Invalid object state exception.
+ */
+public class InvalidObjectState extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public InvalidObjectState() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public InvalidObjectState(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public InvalidObjectState(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public InvalidObjectState(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_INVALID_OBJECT_STATE;
+    }    
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/InvalidRequest.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Invalid request exception.
+ */
+public class InvalidRequest extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public InvalidRequest() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public InvalidRequest(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public InvalidRequest(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public InvalidRequest(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_INVALID_REQUEST;
+    }    
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/InvalidSession.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Invalid session exception.
+ */
+public class InvalidSession extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public InvalidSession() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public InvalidSession(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public InvalidSession(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public InvalidSession(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_INVALID_SESSION;
+    }    
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/ObjectAlreadyExists.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Object already exists exception.
+ */
+public class ObjectAlreadyExists extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public ObjectAlreadyExists() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public ObjectAlreadyExists(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public ObjectAlreadyExists(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public ObjectAlreadyExists(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_OBJECT_ALREADY_EXISTS;
+    }    
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/ObjectNotFound.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Object not found exception.
+ */
+public class ObjectNotFound extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public ObjectNotFound() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public ObjectNotFound(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public ObjectNotFound(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public ObjectNotFound(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_OBJECT_NOT_FOUND;
+    }    
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/exceptions/TimeoutError.java

+package gov.anl.aps.dm.common.exceptions;
+
+import gov.anl.aps.dm.common.constants.DmStatus;
+
+/**
+ * Timeout error.
+ */
+public class TimeoutError extends DmException {
+
+    /**
+     * Default constructor.
+     */
+    public TimeoutError() {
+        super();
+    }
+
+    /**
+     * Constructor using error message.
+     *
+     * @param message error message
+     */
+    public TimeoutError(String message) {
+        super(message);
+    }
+
+    /**
+     * Constructor using throwable object.
+     *
+     * @param throwable throwable object
+     */
+    public TimeoutError(Throwable throwable) {
+        super(throwable);
+    }
+
+    /**
+     * Constructor using error message and throwable object.
+     *
+     * @param message error message
+     * @param throwable throwable object
+     */
+    public TimeoutError(String message, Throwable throwable) {
+        super(message, throwable);
+    }
+
+    @Override
+    public int getErrorCode() {
+        return DmStatus.DM_TIMEOUT_ERROR;
+    }    
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/objects/DmObject.java

+package gov.anl.aps.dm.common.objects;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import gov.anl.aps.dm.common.exceptions.DmException;
+import java.io.Serializable;
+
+/**
+ * Base DM object class.
+ */
+public class DmObject implements Serializable {
+
+    protected Long id = null;
+    protected String name = null;
+    protected String description = null;
+
+    public DmObject() {
+    }
+
+    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 String getDescription() {
+        return description;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    /**
+     * Conversion to JSON string representation.
+     *
+     * @return JSON string
+     */
+    public String toJson() {
+        Gson gson = new GsonBuilder().create();
+        return gson.toJson(this);
+    }
+
+    /**
+     * Encode object.
+     *
+     * @throws DmException in case of any errors
+     */
+    public void encode() throws DmException {
+    }
+
+    /**
+     * Decode object.
+     *
+     * @throws DmException in case of any errors
+     */
+    public void decode() throws DmException {
+    }
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/objects/DmObjectFactory.java

+package gov.anl.aps.dm.common.objects;
+
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+import com.google.gson.reflect.TypeToken;
+import gov.anl.aps.dm.common.exceptions.DmException;
+import java.lang.reflect.Type;
+import java.util.LinkedList;
+import java.util.List;
+import org.apache.log4j.Logger;
+
+/**
+ * DM object factory class.
+ */
+public class DmObjectFactory {
+
+    private static final Logger logger = Logger.getLogger(DmObjectFactory.class.getName());
+    private static final Gson gson = new GsonBuilder().create();
+
+    /**
+     * Create object from JSON string.
+     *
+     * @param <T> template class
+     * @param jsonString JSON string
+     * @param objectClass object class
+     * @return generated object
+     */
+    public static <T extends Object> T createObject(String jsonString, Class<T> objectClass) {
+        logger.debug("Converting JSON string to object " + objectClass + ": " + jsonString);
+        T object = gson.fromJson(jsonString, objectClass);
+        return object;
+    }
+
+    /**
+     * Create DM object from JSON string.
+     *
+     * @param <T> template class
+     * @param jsonString JSON string
+     * @param dmClass DM object class
+     * @return generated DM object
+     * @throws DmException in case of any errors
+     */
+    public static <T extends DmObject> T createDmObject(String jsonString, Class<T> dmClass) throws DmException {
+        logger.debug("Converting JSON string to DM object " + dmClass + ": " + jsonString);
+        T dmObject = gson.fromJson(jsonString, dmClass);
+        dmObject.decode();
+        return dmObject;
+    }
+
+    /**
+     * Create list of DM objects from JSON string.
+     *
+     * @param <T> template class
+     * @param jsonString DM string
+     * @return generated list of DM objects
+     */
+    public static <T extends DmObject> List<T> createDmObjectList(String jsonString) {
+        // This method does not appear to work as template, so we have
+        // to write specific methods for each object type.
+        logger.debug("Converting JSON string to dm object list: " + jsonString);
+        Type dmType = new TypeToken<LinkedList<T>>() {
+        }.getType();
+        List<T> dmObjectList = gson.fromJson(jsonString, dmType);
+        return dmObjectList;
+    }
+
+    /**
+     * Create list of string objects from JSON string.
+     *
+     * @param jsonString JSON string
+     * @return generated list of string objects
+     */
+    public static List<String> createStringObjectList(String jsonString) {
+        logger.debug("Converting JSON string to string object list: " + jsonString);
+        Type dmType = new TypeToken<LinkedList<String>>() {
+        }.getType();
+        List<String> dmObjectList = gson.fromJson(jsonString, dmType);
+        return dmObjectList;
+    }
+
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/objects/Experiment.java

+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+
+package gov.anl.aps.dm.common.objects;
+
+/**
+ * Experiment class.
+ */
+public class Experiment extends DmObject {
+
+    public Experiment() {
+    }
+
+}

src/java/DmWebPortal/src/java/gov/anl/aps/dm/common/utilities/ArgumentUtility.java

+package gov.anl.aps.dm.common.utilities;
+
+import gov.anl.aps.dm.common.exceptions.InvalidArgument;
+import gov.anl.aps.dm.common.exceptions.DmException;
+import java.util.Map;
+import javax.xml.bind.DatatypeConverter;
+
+/**
+ * Utility class for processing and checking function arguments.
+ */
+public class ArgumentUtility {
+
+    /**
+     * Check that input string is not null and not empty.
+     *
+     * @param arg input argument to be checked
+     * @return true if input string is not null and not empty, false otherwise
+     */
+    public static boolean isNonEmptyString(String arg) {
+        return arg != null && !arg.isEmpty();
+    }
+
+    /**
+     * Convert input argument to string.
+     *
+     * @param arg input argument to be checked
+     * @return original argument string representation, or empty string if
+     * argument is null
+     */
+    public static String toNonNullString(Object arg) {
+        if (arg == null) {
+            return "";
+        }
+        return arg.toString();
+    }
+
+    /**
+     * Verify that input string is not null and not empty.
+     *
+     * @param argName name of the argument to be verified; used for error
+     * message
+     * @param arg input argument to be checked
+     * @throws InvalidArgument if input string is null or empty
+     */
+    public static void verifyNonEmptyString(String argName, String arg) throws InvalidArgument {
+        if (arg == null || arg.isEmpty()) {
+            throw new InvalidArgument(argName + " must be non-empty string.");
+        }
+    }
+
+    /**
+     * Verify that input string contains given pattern.
+     *
+     * @param argName name of the argument to be verified; used for error
+     * message
+     * @param arg input argument to be checked
+     * @param pattern string that must be contained in the input argument
+     * @throws InvalidArgument if input string is null or empty, or if it does
+     * not contain specified pattern
+     */
+    public static void verifyStringContainsPattern(String argName, String arg, String pattern) throws InvalidArgument {
+        verifyNonEmptyString(argName, arg);
+        verifyNonEmptyString("Pattern", pattern);
+        if (!arg.contains(pattern)) {
+            throw new InvalidArgument(argName + " must contain pattern " + pattern + ".");
+        }
+    }
+
+    /**
+     * Verify that input integer is not null and greater than zero.
+     *
+     * @param argName name of the argument to be verified; used for error
+     * message
+     * @param arg input argument to be checked
+     * @throws InvalidArgument if input number is null or not positive
+     */
+    public static void verifyPositiveInteger(String argName, Integer arg) throws InvalidArgument {
+        if (arg == null || arg <= 0) {
+            throw new InvalidArgument(argName + " must be a positive number.");
+        }
+    }
+
+    /**
+     * Verify that input double is not null and greater than zero.
+     *
+     * @param argName name of the argument to be verified; used for error
+     * message
+     * @param arg input argument to be checked
+     * @throws InvalidArgument if input number is null or not positive
+     */
+    public static void verifyPositiveDouble(String argName, Double arg) throws InvalidArgument {
+        if (arg == null || arg <= 0) {
+            throw new InvalidArgument(argName + " must be a positive number.");
+        }
+    }
+
+    /**
+     * Verify that input object is not null.
+     *
+     * @param argName name of the argument to be verified; used for error
+     * message
+     * @param arg input argument to be checked
+     * @throws InvalidArgument if input string is null or empty
+     */
+    public static void verifyNonNullObject(String argName, Object arg) throws InvalidArgument {
+        if (arg == null) {
+            throw new InvalidArgument(argName + " cannot be null.");
+        }
+    }
+
+    /**
+     * Add (key,value) pair to map if value is not null or empty.
+     *
+     * @param map target map
+     * @param key key
+     * @param value string that will be added to map if it is not null or empty
+     */
+    public static void addNonEmptyKeyValuePair(Map<String, String> map, String key, String value) {
+        if (value != null && !value.isEmpty()) {
+            map.put(key, value);
+        }
+    }
+
+    /**
+     * Add (key,value) pair to map if value is not null or empty.
+     *
+     * @param map target map
+     * @param key key
+     * @param valueObject object that will be added to map if it has non-empty
+     * string representation
+     */
+    public static void addNonEmptyKeyValuePair(Map<String, String> map, String key, Object valueObject) {
+        if (valueObject != null) {
+            String value = valueObject.toString();
+            if (!value.isEmpty()) {
+                map.put(key, value);
+            }
+        }
+    }
+
+    /**
+     * Base 64 encode.
+     *
+     * @param input input string
+     * @return base 64 encoded string
+     * @throws DmException in case of any errors
+     */
+    public static String encode(String input) throws DmException {
+        try {
+            // Input is twice encoded in order to avoid issues like
+            // '+' being interpreted as space
+            if (input == null) {
+                return input;
+            }
+            String s1 = DatatypeConverter.printBase64Binary(input.getBytes());
+            String s2 = DatatypeConverter.printBase64Binary(s1.getBytes());
+            return s2;
+        } catch (Exception ex) {
+            throw new DmException(ex);
+        }
+    }
+
+    /**
+     * Base 64 decode.
+     *
+     * @param input base 64 encoded string
+     * @return decoded string
+     * @throws DmException in case of any errors
+     */
+    public static String decode(String input) throws DmException {
+        try {
+            // Input is twice encoded in order to avoid issues like
+            // '+' being interpreted as space
+            byte[] ba1 = DatatypeConverter.parseBase64Binary(input);
+            byte[] ba2 = DatatypeConverter.parseBase64Binary(new String(ba1));
+            return new String(ba2);
+        } catch (Exception ex) {
+            throw new DmException(ex);
+        }
+    }
+}