Class PersistentObject

java.lang.Object
   |
   +----PersistentObject

public class PersistentObject
extends Object

Persistent Object Class (derived from BackendUtil.java) This is a class which other objects that need network access extends. There are several abstract methods that the application developer must overload in order to use this class.

Static variables

  public static final int LOAD = 1;
  public static final int SAVE = 2;
  public static final int QUERY = 3;
  public static final int IF_EXISTS = 4;

  // modes for the network operations
  // may include more in the future

  public static final int PUT = 2;
  public static final int GETSTR = 1;
  public static final int MODIFY = 0;
  public static final int GETID = 3;
  public static final int GETATT = 4;
  public static final int DELETE = 5;
  public static final int CONNECT = 6;
  public static final int CONNECTNEW = 7;
  public static final int DISCONNECT = 8;
  public static final int GETATTINFO = 9;

  // types for type-casting 

  public static final int STRING = 1;
  public static final int INT = 2;
  public static final int FLOAT = 3;
  public static final int DOUBLE = 4;
  public static final int BOOLEAN = 5;
  public static final int CHAR = 6;
  public static final int OBJECT = 7;
  public static final int VECTOR = 8;
  public static final int PARENTS = 9;
  public static final int CHILDREN = 10;
  public static final int UNIQUE_ID = 11;
  public static final int ARRAY = 12;

  public static final int CONTAINERS = 9;
  public static final int CONTENTS = 10;

  // indicators for the declaration of functions with same name
  //   by different input type
  // initial value does not matter

  protected static final String STRING_INDICATOR = "str";
  protected static final int INT_INDICATOR = 0;
  protected static final float FLOAT_INDICATOR = 1;
  protected static final double DOUBLE_INDICATOR = 2;
  protected static final boolean BOOLEAN_INDICATOR = true;
  protected static final char CHAR_INDICATOR = 'c';
  protected static final Object OBJECT_INDICATOR = null;
  protected double[] ARRAY_INDICATOR;

  // responses from backend DB server

  public static final int OK_VAL = 200;
  public static final int DUPLICATE_VAL = 300;
  public static final int BAD_REQUEST_VAL = 400;
  public static final int NOT_FOUND_VAL = 404;
  public static final int NOT_FOUND_A_VAL = 405;
  public static final int NOT_FOUND_B_VAL = 406;
  public static final int EMPTY_REQUEST_VAL = 407;
  public static final int NO_ATTACH_VAL = 408;
  public static final int SELF_ATTACH_VAL = 409;
  public static final int PERM_ERROR_VAL = 410;
  public static final int CONT_ERROR_VAL = 411;
  public static final int INTERNAL_ERROR_VAL = 500;
  public static final int ATTACH_NOT_FOUND_VAL = 501;

  // save responses

  public static final int OK = 0;
  public static final int ERROR = 1;
  public static final int DO_NOT_PROCEED = 4;  // new

Static variables

attachObjId: The Id of the object that is being loaded from the data server
containersInMem: Indicates whether the object's containers are in memory
contentsInMem: Indicates whether the object's contents are in memory
currentRelativeClass: The name of the current class returned during parsing
dbId: Unique identifier returned by the data server after a Save()
debugFlag: Flag to print out debugging statements
fieldTypeArray: The array whose contents indicate the type of the field in the corresponding field position of the object
isPersistent: Variable indicating whether the object has been saved before
loadVector
numChildren: The number of children (objects that attaches to it) that the object has
numObjField: The number of object fields the object has
numParents: The number of parents (objects that it attaches to) that the object has
objectClassName: The class name of the object which inherits the Persistent Object class.
port: Port number for the data server
succeedParse: Variable indicating whether a parse (network operation) has been successful
succeedTransmit: Variable indicating whether a network operation has been successful
testNoNet
userId: User Id of the Persistent Object (for network transactions)

PersistentObject(): Constructor of PersistentObject Should never be called explicitly

DEBUG(String): Debug Prints debugging statements if the debug flag is set to true
DeleteObj(): DeleteObj Deletes the object at the data back-end
Disconnect(int, int): Disconnect Voids the connections at the data back-end
GetField(int, boolean)
GetField(int, char)
GetField(int, double)
GetField(int, double[])
GetField(int, float)
GetField(int, int)
GetField(int, Object, int)
GetField(int, String): Get the corresponding contents from an internal vector that parsed and stored the values of a network Load
GetMemberInfo(int, int): Return a MemberInfo object which contains the object class name and object id pair
GetObjFields()
InstancePolicy(PersistentObject): Policy that must be followed after instantiating an object
Load(int)
Load(String): Load (from Persistent Storage over the network).
LoadObject(String, String, int): The actual method call thats being made when a Load() is called.
MakeInstance(): Loads and instantiates a "copy" of the (non-OctCell) object from the data back-end.
NetObjSetup(int, int, String): Network Object Setup method that needs to be run before the object can operate as a persistent object over the network
PostLoadPolicy(Object): Post-object-loading policy, such as handling of dirty bits, etc., that the object developer has to overload
PostSavePolicy(Object): Post-object-saving policy, such as handling of dirty bits, etc., that the object developer has to overload
Save(): Save (Object) Encapsulation of the actual call to SaveObject (returns either OK, ERROR or the Object's UniqueID)
SaveObject(String): Save Object returns OK if save is completed ERROR if not
SavePolicy(Object): Object Saving policy, such as handling of dirty bits, etc., that must/should be done before saving.
SetField(int, boolean, int)
SetField(int, char, int)
SetField(int, double, int)
SetField(int, double[], int)
SetField(int, float, int)
SetField(int, int, int)
SetField(int, Object, int)
SetField(int, String, int): Sets the fields in the Vector holding the fields of the object Non-object types are stored in object that matches mostly closely its type.
SetField(int, Vector, int)
SetNumField(int): Initializes fieldTypeArray.
SetNumObjField(int): Sets the number of Object fields in the object For generation of contents/children purposes
SetObjClassName(String): Sets the Object Class Name for network transaction.
SetObjFields(): Sets up the object's fields into internal data structure.
SetPersistent(boolean): Sets the isPersistent flag which indicates that this object has persistence (has a copy at the data backend) Future operations will then make use of the object's unique id.
SetPort(int): Sets the port number for network transaction.
SetType(int, int): Sets the type of each field.

loadVector

  protected Vector loadVector

numObjField

  protected int numObjField

The number of object fields the object has

fieldTypeArray

  protected int fieldTypeArray[]

The array whose contents indicate the type of the field in the corresponding field position of the object

port

  public int port

Port number for the data server

objectClassName

  public String objectClassName

The class name of the object which inherits the Persistent Object class.

dbId

  protected int dbId

Unique identifier returned by the data server after a Save()

numParents

  protected int numParents

The number of parents (objects that it attaches to) that the object has

numChildren

  protected int numChildren

The number of children (objects that attaches to it) that the object has

containersInMem

  public boolean containersInMem

Indicates whether the object's containers are in memory

contentsInMem

  public boolean contentsInMem

Indicates whether the object's contents are in memory

currentRelativeClass

  protected String currentRelativeClass

The name of the current class returned during parsing

attachObjId

  protected int attachObjId

The Id of the object that is being loaded from the data server

isPersistent

  public boolean isPersistent

Variable indicating whether the object has been saved before

userId

  protected String userId

User Id of the Persistent Object (for network transactions)

succeedTransmit

  protected boolean succeedTransmit

Variable indicating whether a network operation has been successful

succeedParse

  protected boolean succeedParse

Variable indicating whether a parse (network operation) has been successful

debugFlag

  public boolean debugFlag

Flag to print out debugging statements

testNoNet

  protected boolean testNoNet

PersistentObject

  public PersistentObject()

Constructor of PersistentObject Should never be called explicitly

Load

  public abstract boolean Load(String strId)

Load (from Persistent Storage over the network). Needs to be overloaded by the object developer. Return OCT.OK if Load is successful, OCT.ERROR otherwise.

Parameters:: strId - String type of id; intId - Integer type of id

Load

  public abstract boolean Load(int intId)

SetObjFields

  protected abstract void SetObjFields()

Sets up the object's fields into internal data structure. Needs to be overloaded by the object developer

NetObjSetup

  protected void NetObjSetup(int port,
                             int numFields,
                             String objectClassName)

Network Object Setup method that needs to be run before the object can operate as a persistent object over the network

Parameters:: port - Port number of the server; numFields - Number of fields the object has; objectClassName - Name of the class

SetNumField

  protected void SetNumField(int fieldsSize)

Initializes fieldTypeArray. Set the number of fields and the size of the field_type_array and object_field_vector of the object. Needs to be done by the object developer

Parameters:: fieldsSize - Number of fields of the object

SetNumObjField

  protected void SetNumObjField(int numObjs)

Sets the number of Object fields in the object For generation of contents/children purposes

SetType

  protected void SetType(int nthField,
                         int type)

Sets the type of each field. This is a method the Object designer has to overload.

Parameters:: nthField - The position of the field; type - The type of the field

SetPort

  protected void SetPort(int port)

Sets the port number for network transaction. Needs to be done by the object developer.

Parameters:: port - The port number

SetObjClassName

  protected void SetObjClassName(String name)

Sets the Object Class Name for network transaction. Needs to be done by the object developer.

Parameters:: name - Name of the Class

SetField

  protected void SetField(int nthField,
                          String stringField,
                          int type)

Sets the fields in the Vector holding the fields of the object Non-object types are stored in object that matches mostly closely its type.

Parameters:: nthField - The position of the field; Second_Argument - Different data types may be used; type - The type of the field

SetField

  protected void SetField(int nthField,
                          int intField,
                          int type)

SetField

  protected void SetField(int nthField,
                          double doubleField,
                          int type)

SetField

  protected void SetField(int nthField,
                          char charField,
                          int type)

SetField

  protected void SetField(int nthField,
                          boolean boolField,
                          int type)

SetField

  protected void SetField(int nthField,
                          float floatField,
                          int type)

SetField

  protected void SetField(int nthField,
                          Vector vectorField,
                          int type)

SetField

  protected void SetField(int nthField,
                          Object objField,
                          int type)

SetField

  protected void SetField(int nthField,
                          double arrayField[],
                          int type)

LoadObject

  protected boolean LoadObject(String objectClassName,
                               String strId,
                               int intId)

The actual method call thats being made when a Load() is called.

Parameters:: objectClassName - (String) Name of the class; strId - String type of Id of the object; intId - Integer type of Id of the object

MakeInstance

  protected PersistentObject MakeInstance()

Loads and instantiates a "copy" of the (non-OctCell) object from the data back-end.

InstancePolicy

  public abstract void InstancePolicy(PersistentObject pObj)

Policy that must be followed after instantiating an object

Save

  public int Save()

Save (Object) Encapsulation of the actual call to SaveObject (returns either OK, ERROR or the Object's UniqueID)

SaveObject

  protected int SaveObject(String objectClassName)

Save Object returns OK if save is completed ERROR if not

Parameters:: objectClassName - Name of the class

Disconnect

  protected int Disconnect(int parentId,
                           int childId)

Disconnect Voids the connections at the data back-end

Parameters:: parentId - Id of the parent; childId - Id of the child

DeleteObj

  protected int DeleteObj()

DeleteObj Deletes the object at the data back-end

SavePolicy

  protected abstract int SavePolicy(Object obj)

Object Saving policy, such as handling of dirty bits, etc., that must/should be done before saving. The object developer has to overload this method.

Parameters:: obj - Object to be saved

PostSavePolicy

  protected abstract void PostSavePolicy(Object obj)

Post-object-saving policy, such as handling of dirty bits, etc., that the object developer has to overload

Parameters:: obj - Object that has been saved

PostLoadPolicy

  protected abstract void PostLoadPolicy(Object obj)

Post-object-loading policy, such as handling of dirty bits, etc., that the object developer has to overload

Parameters:: Object - that has been loaded

GetMemberInfo

  protected MemberInfo GetMemberInfo(int type,
                                     int index)

Return a MemberInfo object which contains the object class name and object id pair

Parameters:: type - Either PARENTS or CHILDREN; index - The position of the object field

GetField

  protected String GetField(int nthField,
                            String indicator)

Get the corresponding contents from an internal vector that parsed and stored the values of a network Load

Parameters:: nthField - Position of the field; Indictor - Different types according to the type expected

GetField

  protected int GetField(int nthField,
                         int indicator)

GetField

  protected double GetField(int nthField,
                            double indicator)

GetField

  protected boolean GetField(int nthField,
                             boolean indicator)

GetField

  protected char GetField(int nthField,
                          char indicator)

GetField

  protected float GetField(int nthField,
                           float indicator)

GetField

  protected abstract Object GetField(int nthField,
                                     Object indicator,
                                     int nthObject)

GetObjFields

  protected abstract int GetObjFields()

GetField

  protected double[] GetField(int nthField,
                              double indicator[])

SetPersistent

  protected void SetPersistent(boolean flag)

Sets the isPersistent flag which indicates that this object has persistence (has a copy at the data backend) Future operations will then make use of the object's unique id.

DEBUG

  protected void DEBUG(String debugStmt)

Debug Prints debugging statements if the debug flag is set to true

Parameters:: debugStmt - The debugging statement supplied