Ajith Prabhakar’s Weblog

A beginner’s guide to Documentum

Posts Tagged ‘Documentum Tutorials’

Using Java reflection to reduce Code and Development time in DFS

Posted by Ajith Prabhakar on March 11, 2009


Java reflections is one of the most powerful API’s of Java Language, this can be used to reduce code significantly.

Most of the Current Enterprise application consists of different layers and they uses Value objects to transfer data from one layer to another. Inefficient way of using getters and setters of the attributes of Value objects can increase code and development time of application. Effective use of reflection can reduce code and development time significantly.

So lets take a Scenario,  I have a Object type MyObjectType extending from dm_document with 50 additional attributes, so dm_document as of Documentum 6.5 has 86 attributes adding additional 50 attributes that means we have 139 attributes for this object type. Consider a standard Web Application using DFS behind which needs to manipulate (add or edit) instances of this object type, The Service needs to add all these attributes to the PropertySet  of the DataObject representing that instance. Then need to call the appropriate service.

Considering that the bean instance name of MyObjectType is myObjectBean the Standard code will  be something like this


          ObjectIdentity objIdentity = new ObjectIdentity("myRepository");
          DataObject dataObject = new DataObject(objIdentity, "dm_document");
          PropertySet properties = dataObject.getProperties();
          properties.set("object_name", myObjectBean.getObject_Name());
          properties.set("title", myObjectBean.getTitle());

………

objectService.create(new DataPackage(dataObject), operationOptions);

 

In the above code you have to explicitly set individual attributes for the object , the more the number of attributes the more complex and messy code.

Take another Example, where you have to retrieve an Object information and pass it over to the UI layer.


 myObjectBean.setObject_name(properties.get("object_name").getValueAsString());
 myObjectBean.setTitle(properties.get("title").getValueAsString());
 myObjectBean.setMy_Custom_Property(properties.get("my_custom_property").getValueAsString());

This operation can be more complex if you decide to use match the Data Type of your bean with the Object type.

 

So what is the best approach to reduce this complexity? the answer is effective use of reflection API.

Lets take a step to step approach to handle this issue.

 

To understand this better consider the below as the attributes of mycustomobjecttype

 

Attribute Name Attribute Type
first_name String
last_name String
age integer
date_purchased time
amount_due double
local_buyer boolean

 

Java Bean

Create a Java Bean that matches the Object Type


public class Mycustomobjecttype {
  protected String first_name ;
  protected String last_name  ;
  protected int age;
  protected Date date_purchased  ;
  protected double amount_due  ;
  protected boolean local_buyer ;
  public int getAge() {
    return age;
  }
  public void setAge(int age) {
    this.age = age;
  }
  public double getAmount_due() {
    return amount_due;
  }
  public void setAmount_due(double amount_due) {
    this.amount_due = amount_due;
  }
  public Date getDate_purchased() {
    return date_purchased;
  }
  public void setDate_purchased(Date date_purchased) {
    this.date_purchased = date_purchased;
  }
  public String getFirst_name() {
    return first_name;
  }
  public void setFirst_name(String first_name) {
    this.first_name = first_name;
  }
  public String getLast_name() {
    return last_name;
  }
  public void setLast_name(String last_name) {
    this.last_name = last_name;
  }
  public boolean isLocal_buyer() {
    return local_buyer;
  }
  public void setLocal_buyer(boolean local_buyer) {
    this.local_buyer = local_buyer;
  }
}
 

Getting the Values from PropertySet (Loading Java Bean)

……


List<DataObject> dataObjectList = dataPackage.getDataObjects();
DataObject dObject = dataObjectList.get(0);
Mycustomobjecttype myCustomObject = new Mycustomobjecttype();
populateBeanFromPropertySet(dObject.getProperties(),myCustomObject);

……

// See the Reflection in Action here 

public void populateBeanFromPropertySet(PropertySet propertySet, Object bean)
  throws Exception {

BeanInfo beaninformation;
beaninformation = Introspector.getBeanInfo(bean.getClass());
  PropertyDescriptor[] sourceDescriptors = beaninformation.getPropertyDescriptors();
  for (PropertyDescriptor descriptor : sourceDescriptors) {

    Object result = null;
    String name = descriptor.getName();
    if (!name.equals("class")) {
      if (propertySet.get(name) != null) {
        if (descriptor.getPropertyType().getName().equals(
            "int")) {
          result = new Integer(propertySet.get(name)
              .getValueAsString());
        } else if (descriptor.getPropertyType().getName().equals("double")) {
          result = new Double(propertySet.get(name).getValueAsString());

        } else if (descriptor.getPropertyType().getName().equals("boolean")) {
          result = new Boolean(propertySet.get(name).getValueAsString());

        } else if (descriptor.getPropertyType().getName().equals("java.util.Date")) {
          DateProperty dat = (DateProperty)propertySet.get(name);
          result = dat.getValue();
        }else {
          // none of the other possible types, so assume it as String
          result = propertySet.get(name).getValueAsString();
        }
        if (result != null)
          descriptor.getWriteMethod().invoke(bean, result);
      }
    
    }
  }
}
  

Setting Values to Property Set

 


public DataPackage createContentLessObject(Mycustomobjecttype myCustomType) throws Exception {
ObjectIdentity objectIdentity = new ObjectIdentity("testRepositoryName");
DataObject dataObject = new DataObject(objectIdentity, myCustomType.getClass().getName());

PropertySet properties = populateProperties(myCustomType);
properties.set("object_name",myCustomType.getFirst_name()+myCustomType.getLast_name() );
dataObject.setProperties(properties);

DataPackage dataPackage = new DataPackage(dataObject);
OperationOptions operationOptions = new OperationOptions();

return objectService.create(dataPackage, operationOptions);

}

 


// Reflection in Action  
public PropertySet populateProperties(Object bean)throws Exception {
BeanInfo beaninfo;
PropertySet myPropertyset = new PropertySet();
  beaninfo = Introspector.getBeanInfo(bean.getClass());
  PropertyDescriptor[] sourceDescriptors = beaninfo
      .getPropertyDescriptors();
  for (PropertyDescriptor descriptor : sourceDescriptors) {
    String propertyName = descriptor.getName();
    if (!propertyName.equals("class")) {
        // dont set read only attributes if any
        // example r_object_id 
      if (!propertyName.startsWith("r")) {
        Object value = descriptor.getReadMethod().invoke(bean);
        if (value != null) {
          myPropertyset.set(propertyName, value);
        }

      }

    }

  }
  return myPropertyset;
}

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Non Qualifiable properties and Property Bag in Documentum Objects

Posted by Ajith Prabhakar on April 11, 2008


Before getting into details of Property Bags lets quickly see what are Qualifiable and Non-Qualifiable properties?

 

Qualifiable Properties

Most of the Object attributes are Qualifiable properties. The properties are qualifiable if it is saved (persisted) in a column of that Objects underlying tables (_r or _s table) in the Database. Attributes are Qualifiable by default.  I am not getting into much detail of Qualifiable properties here. See the following link for more on this

 

Object Attribute :- Repeated and Single Value Attributes in Database

 

Non – Qualifiable Properties

These Attributes of objects does not have column of its own in the Object’s underlying _r or s tables. They are saved in the serialized format in the i_property_bag property of the underlying object. See the below noted bullet points that reveal some interesting facts about Non – Qualifiable attributes.

 

·         Though these properties can be returned using a DQL Query, this cannot be used in the Qualifying clause [in Where Clause of the Query]. The Exception to this rule is that Non-Qualifiable properties can be used in the where clause of FTQL queries

·         These properties can be full text indexed.

·         IF the Non-Qualifiable properties are part of the select part of the Query, the query should have r_object_id in the select list.

·         If a property is Non-Qualifiable and it is of type String the length of that attribute must be less than the value of max_nqa_string key in the server.ini (Only if this key has a value set in server.ini) (The default value is 2000)

 

 

Lets See Few Related DQL’s

 

The following DQL creates an object type mycustomtype with first name a Qualifiable Attribute and country a Single Non-Qualifiable attribute and phone a Non Qualifiable Repating attribute.

 

CREATE TYPE “mycustomtype” (“firstname” string(64), country string(64) NOT QUALIFIABLE, phone string(10) REPEATING NOT QUALIFIABLE ) WITH SUPERTYPE “dm_document”

 

The following Query will create an object of type mycustomtype (You may notice that there is no difference in the create Query when compared with Qualifiable Properties

 

CREATE mycustomype OBJECT SET “firstname” = ‘Hello World’, SET “country”= ‘US’, SET phone [0]= ‘1111111111’

 

The following Query will return the Attributes from mycustomtype.
Note:
Make sure that you have r_object_id in the select query if you have non-Qualifiable attributes otherwise you will get following error
DM_QUERY2_E_MISSING_OBJECTID_IN_SELECT_LIST

 

Select r_object_id, firstname, country from mycustomype;

 

What is Property Bag

Property bag is a relatively new term in Documentum. This is a property, which is used to store other properties and values of an Object.  Non Qualifiable properties and its values of an Object is stored in its property bag (both Single and Repeated)

Other than Non-Qualifiable properties Property bag can also hold Properties and values of Aspect if the aspect properties are enabled with OPTIMIZEFETCH.

 

i_property_bag and r_property_bag

 

The i_property_bag property is defined in dm_sysobject , This Attribute is of datatype String and  can hold up to 2000 characters. This makes sure that all the object types that are inheriting from dm_sysobject have the ability to have its own property bag.

 

In the scenarios where you don’t have a Parent type defined in the Object definition and you create a non-Qualifiable attribute this property is automatically added to the object type.

 

If you add property bag to an object type it can never be removed from that object type.

 

The r_property_bag is silently added to the Object’s type definition when we add i_property_bag. This repeating attribute property is used to store the overflow from the i_property_bag. That means if the names and values of properties stored in i_property_bag exceed 2000 chars, the overflow is stored in r_property_bag. This is repeating string property with 2000 characters.

 

Download This Study Note (PDF)

 

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Few Important Object Types in Documentum

Posted by Ajith Prabhakar on April 7, 2008


 

 

Documentum is an Object Oriented Content Management Systems. Everything in Documentum is considered as Objects, This includes all the things that user manipulates, or the content server saves. From the User to Document, everything in Documentum is different type of Object. The whole Object types in Documentum has been structured in a Hierarchal model. Means All the Attributes from the super types are extended to the sub types. In other sense the attributes of Super types are visible and accessible from the Subtypes.

 

Lets see some of the important and most commonly used object types here. 

 

Note: This is just to give an insight of Documentum Object model. Please read Object Reference Manual for very detailed information on All Object types and its attributes.

Persistence Object 

This type is the super type of all the object types that are saved in Documentum. Each time user creates an object instance of Persistence object type they are objects stored in the repository, this can be retrieved at a later point of time from the Content server.

 

This Object type is an internal type and you cannot create an instance of it.  There are only 3 attributes for this object type they are. These attributes are extended to all the object types across the Documentum.

 

1)      r_object_id
A Unique ID of an object. Content server generates this ID when you create an object of any type. There are some interesting aspects about r_object_id. r_object_id is 16 characters long and its alpha numeric.

The characters from position 01 to 02 indicate the object type tag (09 = document, 0b = folder, etc.).

The characters from position 03 to 08            Repository id (Same for every object in a Repository, but different for each Repository)     

The characters from position 09 -to 16            is unique identifier for this object

 

Consider the following r_object_id 09012a5b80075dc2 in this 09 is the Object type Tag, 012a5b is the repository ID and 80075dc2 is the unique id that represents this object.

2)      i_vstamp
This property is basically used for versioning, each time you save changes to the object the value of this property increases by 1 and this also helps to check the concurrent modification of object.

3)      i_is_replica
This property of object that indicates whether that object is replica of  an object in a remote repository

 

Sys Object (extended from Persistence Object) (dm_sysobject)

Most of the commonly used object types are extended from this object type. Most common Subtypes include Document, Folder, and Cabinet etc.

There are 4 important characteristics for this Object type. They are

1)      Only dm_sysobject and its subtypes can be defined as shareable

2)      They can have permissions associated (Attach ACL).

3)      Sys object can belongs to a folder (Exception Cabinet – Cabinet cannot belong to a folder)

4)      Sys object can have content attached to it.

ACL  (extended from Persistence Object) (dm_acl)

This object type plays a very vital role in implementing security to the Documentum server if the security model of Content Server is set to ACL. All ACL objects r_object_id starts with letters 45

User (extended from Persistence Object)(dm_user)

This stores all the information about user in a Documentum repository, Only a Super user or Sys Admin can create/activate/delete/deactivate a user. All User Object’s r_object_id starts with letters 11

Group (extended from Persistence Object)(dm_group)

A group is the group of users and it can include another groups also.  This object stores information about a specific group, which includes r_object_id of all the member users, groups. This has identifier which determines whether it’s a group or a role. All the group objects has r_object_id starting with 12

Document (extended from Sys Object)(dm_document)

Documents represent a real document in Repository; it can be associated with 0 or more content objects also.  A Document may be a real document or virtual document. All objects of this type has a r_object_id starting with 09

Folder (extended from Sys Object)(dm_folder)

Folders are basically used to organize contents. All the sys objects that are created should be linked with at least one folder or a Cabinet. An Object can be linked with multiple folders also. All objects of this type has a r_object_id starting with 0b

Cabinet (extended from Sys Object)(dm_cabinet)

Cabinet is a special type of folders and its used to organize sys object in a repository. Cabinets are the highest in the Folder Hierarchy in Documentum. A Cabinet cannot be placed inside a Cabinet or a Folder and that makes it special. All objects of this type has a r_object_id starting with 0c

Registered (extended from Sys Object)(dm_registered)

Represents a Registered table in a RDBMS in Documentum. It has the table, name, column names and it s data type saved.  All objects of this type has a r_object_id starting with 19

  

Object types that are not saved in Repository

There are few Object types in Documentum, which are not to be saved in the repository. These are some object types that are created on runtime and destroyed as its use is over. Here is the list of those object types.

 

Client config (New in D6)

A Client config object is created at every time when DFC is initialized. This has all the properties in the dfc.properties file.

Connection Config

This type describes a session’s connection to a specific repository

Docbroker Locator

A docbroker locator object contains information about each connection broker that the

client DMCL can access

Docbase Locator

This has information all repositories registered with a connection broker

Server Locator

A server locator object has information about all the servers registered to a connection broker

Session Config

Contains information about an open repository session

 

Download this Study Note (PDF)

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