Examples of org.dmd.dmc.DmcObject

org.dmd.dmc.DmcObject
The Dark Matter Core (DMC) Object is the basic entity on which all aspects of the Dark Matter Data framework are based.
The DMC object is basically a typed holder for a collection of attributes. At this level, the DMC is abstract; it is the derived, auto-generated, Dark Matter Objects (DMOs) that give a DMC identity. Storing the attributes as a collection introduces a small amount of overhead to DMOs, but allows for operational concepts such as serialization, modification, formatting, cloning, staging etc. that are all provided automatically. It also allows for the use of DMOs in environments where accessing values by name (for example in GWT-based applications) is a necessity.
In addition to the attribute collection, the only constant overhead for a DMC object is the info Vector. The info Vector will contain various information at various times during the life cycle of an object, but will only take up additional space as required. Again, there is some overhead, but the benefits of that overhead are very useful.
There are currently 6 additional pieces of information stored for a DMC object:
- CONTAINER[0] - if the DMO is wrapped by a DMW generated class, this holds the reference to the DMW. This supports the automatic casting of a DMO to its DMW wrapper type via the use of auto generated Iterable classes.
- BACKREFS[1] - in order to behave nicely with Java garbage collection, the named object reference mechanisms of Dark Matter will maintain knowledge of which resolved reference attributes are pointing at a particular DMO instance. If the DMO is deleted, it can automatically remove the reference to itself in the reference attributes. This is a work around for the fact that the GWT JRE Emulation mechanisms don't support the java.lang.ref.WeakReference mechanisms. Back reference tracking must be enabled via the DmcOmni.instance.backRefTracking() method.
- MODIFIER[2] - the Modifier is used to record changes that are made to an object so that the modifications can be distributed via the Dark Matter Protocol Event (DMPEvent) and then applied to remote objects. This mechanism supports very succinct notification of changes to objects and only includes the object deltas, not the entire object. The MODIFIER and the LASTVAL (described next) will only exist on the object if it has been modified.
- LASTVAL[3] - the LASTVAL is just a handle to the last value that was added to or deleted from a multi-valued attribute. It is required to support the Modifier concept.
- MODREC[4] - the MODREC flag is just a Boolean to indicate that the object is a temporary construct that will be used as a MODification RECorder to populate a DmcTypeModifier with a set of changes to be applied to an object in a cache or a remote object. This value is set when a DMO/DMW is constructed with a DmcTypeModifierMV. This distinction is required to prevent applying backrefs to an object when an object referring to it is in MODREC mode. If we didn't keep track of this, we would wind up tracking references twice.
- STAGING[5] - the STAGING flag is used to indicate that the current object is a staging area for the evaluation of a set of modifications that are about to be applied to an existing object. This mechanism exists to facilitate the application of validation rules to the results of a set of modifications. Instead of cloning an entire object, which could be costly, a staging object will only clone the attributes of a target object that are referred to in the modifications; the other attributes of the staging object are merely references to those in the target object. The staging object can then be passed to the rule manager for validation and, if the resulting object is valid, the modifier can be applied to the target object. While in STAGING mode, the object reference tracking mechanisms are disabled so that we don't track changes that could, in the end not be valid (and also, we don't want to apply them twice).

  // DmcCacheIF
  
  @Override
  public void applyModification(DmcNamedObjectIF referringObject, DmcTypeModifier mods) throws DmcValueExceptionSet, DmcValueException {
    System.out.println("TestDataCache.applyModification() ");
    DmcObject target = (DmcObject) referringObject;
    
    SetRequestDMO request = new SetRequestDMO();
    request.setTarget(referringObject.getObjectName());
    request.add(mods.getAttributeInfo(), mods);
    
    System.out.println(request.toOIF());
    
    System.out.println("Before:\n" + target.toOIF(15) + "\n");
    
    target.applyModifier(mods);
    
    System.out.println("After:\n" + target.toOIF(15) + "\n");
    
  }

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    return null;
  }


  @Override
  public DmcObject getDMOInstance(DmcInputStreamIF dis) throws Exception {
    DmcObject rc = null;
    
    // READ: the number of classes in the objectClass
    int classCount = dis.readInt();
    
    // READ: the construction class ID
    int classID = dis.readInt();
    
    // Try to find the class in the schema
    ClassDefinition cd = schema.isClass(classID);
    
    if (cd == null)
      throw new IllegalStateException("Unknown class ID: " + classID + " ensure that you have loaded the required schemas.");
    
    // Tricky stuff: we always try to instantiate the wrapper for the object so that 
    // we can support the DMW environment i.e. the DMO will have a handle to its
    // container. If something goes wrong, we fall back to directly instantiating
    // the DMO.
    DmwWrapper wrapper = null;
    try {
      wrapper = cd.newInstance();
    }
    catch(Exception ex){
      // Just fall back to instantiating the DMO
    }
    
    if (wrapper == null)
      rc = cd.newDMOInstance();
    else
      rc = wrapper.getDmcObject();
    
    // Add the auxiliary classes if they exist
    if (classCount > 1){
      for(int i=1; i<classCount; i++){
        classID = dis.readInt();
        cd = schema.isClass(classID);
        rc.addAux(new ClassDefinitionREF(cd.getDMO()));
      }
    }
    
    return(rc);
  }

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    try {
      if ( (getEventTypeDMP() == DMPEventTypeEnum.CREATED) || (getEventTypeDMP() == DMPEventTypeEnum.LOADED)){
        if (getSourceObject() == null)
          throw(new IllegalStateException("Malformed DMPEvent. Missing source object for a CREATE event."));
        
        DmcObject clonedSourceObj = getSourceObject().getNew();
          
        int nonPersistentCount = 0;
        for(DmcAttribute<?> attr: getSourceObject().getAttributes().values()){
          if (attr.getID() == DmcObject.__objectClass.id)
            continue;
          if (attr.getAttributeInfo().dataType == DataTypeEnum.PERSISTENT){
            clonedSourceObj.add(attr.getAttributeInfo(), attr.cloneIt());
          }
          else
            nonPersistentCount++;
        }

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          throw(new IllegalStateException("Dropping the sliced modifier in our shallow copy shouldn't throw an exception!"));
        }
      }
    }
    else if ( (getEventTypeDMP() == DMPEventTypeEnum.CREATED) || (getEventTypeDMP() == DMPEventTypeEnum.LOADED)){
      DmcObject sliced = getSourceObject().getSlice(dsi);
//      if (sliced.numberOfAttributes() > 1){
        // We have more than the objectClass attribute so create the new event
        rc = new DMPEvent((DMPEventDMO) this.getDMO().shallowCopy());
        
        rc.setSlice(dsi.getName());

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  }




  @Override
  public DmcObject findNamedDMO(DmcObjectName name) {
    DmcObject     rc   = null;
    MvwDefinition   d   = allDefs.get(name);
    
    if (d == null){
      // Fall back and check the schema
      rc = schema.findNamedDMO(name);

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   * @throws IOException
   * @throws ResultException 
   * @throws Exception 
   */
  public DmcObject deserialize(DmcInputStreamIF dis) throws Exception {
    DmcObject dmo = null;
    
    // READ: the number of classes in the objectClass
    int classCount = dis.readInt();
    
    // READ: the construction class ID
    int classID = dis.readInt();
    
    // Try to find the class in the schema
    ClassDefinition cd = schema.isClass(classID);
    
    if (cd == null)
      throw new IllegalStateException("Unknown class ID: " + classID + " ensure that you have loaded the required schemas.");
    
    // Instantiate the object
    dmo = cd.newDMOInstance();
    
    // Add the auxiliary classes if they exist
    if (classCount > 1){
      for(int i=1; i<classCount; i++){
        classID = dis.readInt();
        cd = schema.isClass(classID);
        dmo.addAux(new ClassDefinitionREF(cd.getDMO()));
      }
    }
    
    // READ: the number of attributes
    int attrCount = dis.readAttributeCount();
    
    for(int i=0; i<attrCount; i++){
      DmcAttribute<?> attr = dis.getAttributeInstance();
      
      // READ: the current attribute
      attr.deserializeIt(dis);
      
      if (attr.getAttributeInfo().valueType == ValueTypeEnum.SINGLE)
        dmo.set(attr.getAttributeInfo(), attr);
      else
        dmo.add(attr.getAttributeInfo(), attr);
    }
    
    return(dmo);
  }

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     * by this class definition.
     * @throws ResultException 
     */
    public DmcObject newDMOInstance() throws ResultException
    {
      DmcObject rc = null;


        if (dmoClass == null){
            // The first time we try to create an object this way, get our
            // object class so we can call Class.newInstance()
            try{

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  ////////////////////////////////////////////////////////////////////////////////
  // DmcAttribute abstract overrides


  public DmcObject typeCheck(Object value) throws DmcValueException {
    DmcObject rc = null;
    
        if (value instanceof DmcObject){
            rc = (DmcObject)value;
        }
        else if (value instanceof DmcContainerIF){

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    public DmcObject deserializeValue(DmcInputStreamIF dis) throws Exception {
//    DmcTypeClassDefinitionREF  oc   = (DmcTypeClassDefinitionREF) dis.getAttributeInstance();
//    oc.deserializeIt(dis);
//      DmcObject rc = dis.getDMOInstance(oc.getMVnth(0).getObjectName().getNameString());
//      rc.deserializeIt(dis);
      DmcObject rc = dis.getDMOInstance(dis);
      rc.deserializeIt(dis);
      return(rc);
    }

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  }


  @Override
  public DmcObject findNamedDMO(DmcObjectName name) {
    DmcObject rc = schema.findNamedDMO(name);
    
    if (rc == null)
      return(cache.findNamedDMO(name));
    
    return rc;

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org.dmd.dmc.types.DmcTypeNamedObjectREF

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