Relationship and Virtual Documents in Documentum

This Post explains how the concept of relationships and virtual documents can be used to relate objects in Documentum using Documentum Foundation Classes (DFC).

Definitions:

1. Relationship: A relationship implies a connection between two objects. When an object is related to another object then we can define which object is the parent object or the child object or if they are equal. Relationships are system-defined as well as user-defined. In the BOK, we confine our self to user-defined relationships.
2. Virtual Document: In Documentum, a document which holds other documents i.e. a document which acts as a container is called as a virtual document. A virtual document can contain other virtual documents. The document which acts as a container is called the parent document while the documents which are contained in parent document are called as child documents.

Overview on relationship:

Two built-in object types dm_relation and dm_relation_type are to be used to create relations between any two objects. The dm_relation_type object defines the behavior of the relation. The dm_relation object identifies the dm_relation_type object and the two objects between which the relation needs to be created. Pictorially it can be shown as:

Figure-1

The dm_relation_type object has following attributes:

1. child_parent_label: It defines the child to parent feature of the relation.
2. parent_child_label: It defines the parent to child feature of the relation.
3. description: It gives the general description of the relation.
4. parent_type: It defines the type of objects that will act as parents.
5. child_type: It defines the type of objects that will act as child.
6. direction_kind: It defines the nature of relationships between the objects. The expected values are:

a)    1 – Parent to Child

b)    2 – Child to Parent

c)    3 – Objects are at equal level

7. integrity_kind: It specifies the type of referential integrity used when either of the two related objects has to be deleted. The expected values are:

a)    0 – Any of the two related objects can be deleted.

b)    1 – As long as the relation exists, neither of the related objects can be deleted.

c)    2 – If one of the related objects gets deleted, other one also gets deleted.

1. relation_name: Specifies a name for the relation
2. security_type: It indicates the type of security to be used for the relation object. The valid values are:

a)    SYSTEM: If this value is used, then super-user privileges are required for creating, deleting or modifying the relationships pertaining to this dm_relation_type object.

b)    PARENT: In this case, the ACL for the relation is inherited from the parent object in the relation and RELATE permission is required to create, modify, or drop the relation. The exception to this is if the parent object is not a subtype of dm_sysobject, then no security will be enforced.

c)    CHILD: In this case, the ACL for the relation is inherited from the child object in the relation and RELATE permission is required to create, modify, or drop the relation. The exception to this is if the child object is not a subtype of dm_sysobject, then no security will be enforced.

d)    NONE – In this case, no security is applied. All users can create, modify or delete this kind of relationship.

The dm_relation object has following attributes:

1. child_id: It is the r_object_id or i_chronicle_id of the child object in this relation. If i_chronicle_id is used, then ‘child label’ attribute can be used to bind the parent object to a particular version of child.
2. parent_id: The r_object_id or i_chronicle_id of the parent object in the relations. If the attribute ‘permanent_link’ is set to TRUE then only use the i_chronicle_id of the object.
3. permanent_link: If every new version of the parent object has to be related with the child object, then the value for this attribute must be set to TRUE and i_chronicle_id should be used in the parent_id attribute. By default the value is FALSE.
4. relation_name: It specifies the value of relation_name attribute of the dm_relation_type object that defines the type of relationship.
5. child_label <Optional>: If i_chronicle_id is used in the attribute ‘child_id’, then the label of the version of the child object is to be specified here.
6. description <Optional>: Specifies the description.
7. effective_date<Optional>: Not used by the system, a user-defined date. Custom logic could check this date to determine the state of the relationship.
8. expiration_date<Optional>: Not used by the system, a user-defined date. Custom logic could check this date to determine the state of the relationship.
9. order_no<Optional>: Not used by the system. Custom logic could use this integer value to order a set of relationships.

• Creation of dm_relation_type object using DQL: The query used to create a dm_relation_type object is as follows:

create dm_relation_type object

set child_parent_label = ‘<Child to parent label>’,

set parent_child_label = ‘<Parent to child label>’,

set description = ‘<Description>’,

set parent_type = ‘<Document type>’,

set child_type = ‘<Document type>’,

set direction_kind = <0 or 1 or 2>,

set integrity_kind = <0 or 1 or 2>,

set relation_name = ‘<Name of Relation>’,

set security_type = ‘<SYSTEM or PARENT or CHILD or NONE>’

• Creation of dm_relation object using DFC: Following methods which returns an object of type dm_relation can be used to create a dm_relation object.

1. addChildRelative(relationTypeName, childId, childLabel, isPermanent, description): This method has to be invoked on the object which is going to act as Parent in the relation. The parameters it takes are

a)    relationTypeName – Name of a valid dm_relation_type object.

b)    childId – The r_object_id or i_chronicle_id of the child object of the relation.

c)    childLabel – Version label of the child object. If this is ‘null’, the relation will contain no child label.

d)    isPermanent – Specifies if the link permanent. Valid values are TRUE or FALSE

e)    description – Specifies the description for the relation object. If ‘null’, the relation object will not have a description.

2.addParentRelative(relationTypeName, parentId, childLabel, isPermanent, description): This method has to be invoked on the object which is going to act as Child in the relation. It takes the same parameters as the method addChildRelative takes except instead of r_object_id or i_chronicle_id of the child object we pass the r_object_id or i_chronicle_id of the parent object as the parameter parentId.

Note: dm_relation object can be created through DQL also.

Overview on virtual document:

Virtual document provides a way for combining documents in various formats into one consolidated document. For e.g. one word document, one pdf document and one image can be combined to form one virtual document. There is no limitation regarding nesting of documents. One particular version or else all of the versions of a component can be combined with a virtual document. Two object types are used to store information about virtual documents. They are:

1. Containment Object Type: It stores the information that links a component to a virtual document. Every time a component is added to a virtual document, a containment object is created for that component. The attributes of this object type can be set by the methods AppendPart, InsertPart, UpdatePart.
2. Assembly Object Type:  An assembly object provides a snapshot of a virtual document at a given instance.

Creation of a virtual document using DFC:

A document can be converted to a virtual document by invoking the method setIsVirtualDocument on it. This method sets the r_is_virtual_doc of the document.

Note: Virtual documents can also be created using clients such as Webtop, DA etc as well as through DQL.

Requirement in the project:

Consider there are three main documents A, B and C. Essentially, A, B and C represent different contracts. Consider another set of documents A1, A2, A3, B1, B2, B3, C1, C2 and C3. A1, A2 and A3 are directly related to A, B1, B2 and B2 are directly related to B, C1, C2 and C3 are directly related to C. Also, A is related to B (A is child, B is parent), B is related to C (B is child and C is parent), and C is related to A (C is child and A is parent). The documents being referred here are Documentum documents of a certain system-defined or user-defined document type.

As per the requirements:

1. For every new version of the documents the existing relations should be valid.
2. From the document A, we should be able to navigate to A1, A2 and A3 and also to the documents B and C. Similarly for B and C.
3. Depending on a particular attribute of main documents (A, B and C), there should be dynamic creation or deletion of relationships between contracts.

Resolution of requirement # 1:

Issue encountered:

Documentation says that when a dm_relation object is created with attribute values permanent_link = TRUE and child_label = ‘Current’ then for every new version of parent or child a new instance of the dm_relation object is created and the relation is created between the latest versions of child object and parent object. But on implementation of the same, always the latest version of the parent object was related to child object between which the relation was initially created.

Issue resolution:

To maintain the relation across the current versions of document and for easy navigation from parent to child documents the concept of virtual documents in addition to that of relationship was used.

All the main documents A, B and C were converted to virtual documents. The child documents A1, A2 and A3 were added as children to the newly converted virtual document A. For this the following DFC methods were used in the same order as specified:

1. asVirtualDocument(lateBindingValue, followRootAssembly): This method is invoked on a virtual document (in this case on A, B and C) and it returns the virtual document representation of the virtual document object on which it is invoked. The parameters it takes are2.   getRootNode(): This method is invoked on the virtual document representation of a virtual document. It returns the root node of the virtual document. The root node is essentially the virtual document which is at the topmost hierarchy of virtual document tree. (In our case A, B and C are root nodes)
1. lateBindingValue – the version label of the virtual document. To meet our requirement the value should be “Current”.
2. folowRootassembly: If the value is set to TRUE, the assembly specified by the root node will be used as the virtual document.
3. getRootNode(): This method is invoked on the virtual document representation of a virtual document. It returns the root node of the virtual document. The root node is essentially the virtual document which is at the topmost hierarchy of virtual document tree. (In our case A, B and C are root nodes
2. addNode(parentNode, insertAfterNode, objectChronId, binding, followAssembly, overrideLateBindingValue): This method is invoked on the root node of a virtual document. This method adds a new node to the virtual document on which it is invoked. The parameters it takes are:

• parentNode: The root node.
• insertAfterNode: A virtual document node that will immediately precede the new node in the virtual document’s hierarchy. If this parameter is null, the new node is placed as the first child of parentNode.
• objectChronId: i_chronicle_id of the document which is to be added as child to the virtual document. (In or case i_chronicle_id of A1, A2, A3, B1, B2, B3, C1, C2 and C3).
• binding: The version label of the version of the child document with which we want to bind the child document with the virtual document.
• followAssembly: It is set to TRUE if the follow_assembly attribute has to be set to TRUE for the component.
• overrideLateBindingValue: It is set to TRUE if the version label identified in binding is to be used to resolve late-bound descendents of this component.

So using the concept of virtual document always the current versions of document are present in the parent virtual document. Thus the current versions of A and A1, A2, A3 are always related. And since A has been converted to virtual document, we can navigate to A1, A2 and A3 by just clicking on A.

Resolution of requirement # 2:

Now using the concept of relationship, a relation was created between A and B, B and C, A and C each. Thus navigation across the different contracts A, B and C was possible. Pictorially this can be shown as:

Figure-2

In the above figure the arrow denotes the relationship between two documents.

Resolution of requirement #3:

Requirement #3 states that there should be dynamic creation or deletion of relations between main documents depending on a particular attribute, say, attr. The value of attr for, let’s say, document A determines to which document, A will act as child. If the value of attr for document A is changed so as to imply that A and B are no longer related, then the relation object existing between A and B should be destroyed. If the new value points toward new document D, then a relation has to be created between A and D.

So the change in value of that particular attribute needs to be intercepted. The interception can be done as follows:

1. Write a TBO (Type based object) for the document type to which A belongs to.                

 Note: For details on TBO refer BusinessObjectsDevelopersGuide.pdf provided by Documentum.

1. In the TBO, override the method setString(attribute name, value of attribute), if the attribute attr is single-valued attribute or appendString(attribute name, value of attribute), if it is multi-valued attribute. These two methods captures all the attributes and their values for a document type. setString captures the single-valued attributes while appendString captures the multi-valued attributes.
2. In either of the method, compare the old value of attribute attr with the new one. If there’s any change destroy all the existing relations which involves the document A as child. This can be done using the DFC method removeParentRelative(relationTypeName,parentId,childLabel).  Invoke this method on A. The parameters it takes are:Now use the method addParentRelative as explained, to relate document D as parent to document A.
   1. relationTypeName – Name of the relation object.
   2. parentId – r_object_id of parent object.
   3. childLabel – version label of child object.
3. Every time the value is changed for attribute attr and the document is saved, the corresponding TBO is invoked and the above mentioned methods will be executed. Thus dynamic creation or deletion of relations can be achieved.

Conclusion: Thus the concept of relationships and virtual documents can be used together to relate objects in Documentum using Documentum Foundation Classes (DFC).

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