Class hierarchy and inheritance

The Pega 7 Platform class hierarchy is a hierarchy for storing rules and data, not for Java variables or Java methods. Each class, whether abstract or concrete, can contain properties, activities, data transforms, and many other rules. Only objects in concrete classes can be saved as persistent or enduring instances in the PegaRULES database.

At the top of the hierarchy is the ultimate base class, identified by the keyword @baseclass. Its immediate child classes are known as the base classes. Concrete classes under two of these base classes, Rule- and Data-, hold rules and data instances that application developers create and update to build their application.

Instances of concrete classes derived from the Assign- base class and the Work- base class (and perhaps a few others) hold the dynamic transaction data and status details as your Pega 7 Platformapplication operates.

When any object is held in memory, it has an XML (eXtensible Markup Language) format visible on your clipboard as pages and property name-value pairs. When stored into the PegaRULES database, the persistent object instance becomes a row in a SQL-based relational database table. Three data classes, accessed through the Database, Database Table, and Class Group forms, together determine how Pega 7 Platform saves and retrieves the XML data as relational database rows.

You application may need custom classes derived from these base classes:

• Work- base class (common)

• Assign- base class (rare)

• Data- base class (common)

• Embed- base class (occasional)

• Index- base class (occasional)

• History- base class (created automatically)

Careful planning and analysis are important before creating the new classes, to understand their interrelationships and plan their positions in the standard class hierarchy. Maximizing reuse of standard classes, standard properties, and other standard rules is a proven tactic for fast development at minimum effort.

A database administrator can help design and plan Database Tables and class groups, as these decisions can influence database performance and backup needs.

Many rules apply to a specific class, and potentially to subclasses of that class. Rule resolution is the Pega 7 Platform search and lookup algorithm that uses inheritance to search through parent classes in a defined sequence for a rule. For example, if a property named CreditLimit is needed at runtime in the context of a class named Delta- CustomerCard, the system may search for a property with this name in several classes:

• Delta-CustomerCard

• Delta-

• Work-Cover-

• Work-

• @baseclass (the topmost class)

The search ends when a rule is found. Settings in the class rule (Rule-Obj-Class rule type) define whether and how two mechanisms — directed inheritance and pattern inheritance — are employed during this search.

Class Structure

How to replicate (clone) a class group and class structure

At times, when following installation or migration of a RuleSet or product ZIP file, it may be desirable to mirror or "clone" a class structure.

For example, two similar but separate companies Delta and Omega can use one application in the MORTGAGE RuleSet. The MORTGAGE application includes several work types, each a class belonging to a single class group (say Mortgage).

Both Delta and Omega will use the same rules, but will apply the rules to distinct work types belonging to two distinct class groups (work pools). Users at each company can create work items identified as W-1234, and reports for each company will include only work items, assignments, and other data for that company.

The classes needed are similar to these:

• Delta-Div-Work-Mortgage-WorkType1

• Delta-Div-Work-Mortgage-WorkType2

• Omega-Div-Work-Mortgage-WorkType1

• Omega-Div-Work-Mortgage-WorkType2

and so on.

To support such situations, the Direct Inheritance wizard creates a new set of classes (one of which corresponds to a class group) that match the classes below a specified class. Through directed inheritance, the new classes inherit rules from those in the MORTGAGE RuleSet.

Procedure

Select Designer Studio> Data Model >Classes and Properties > Clone Class Group to start the Direct Inheritance wizard.

1. Complete the first form with the following information:

• The RuleSet that contains the classes to be replicated

• The class group (work pool) to be replicated

• A new name for the class group to be created

• Choose any value for the strategic process; this field is not used

2. Click Next. Complete the second form:

• The RuleSet to contain the new classes

• Checks for each class to be replicated

3. Click Next to start replication. The final form identifies the classes, Database Table, and class group that were created.

Standard classes derived from the Data- base class

About thirty standard concrete classes derived from the Data- base class record information that is entered by developers or other staff. For more information, see Data- classes by class name.

Your system also includes several concrete Data- classes that it uses internally while it operates. The installation process creates instances of many of these classes. Later, as the system operates, it creates instances of others indirectly. In most cases, no form is defined, so you cannot directly review the instances of these classes.

To access reports on Data- classes, click Designer Studio > Application > Inventory > Inventory Reports. In the Category menu, select Data.

For a list of those concrete Data- classes that developers can maintain using forms, see Data classes by name.

A dot () marks those classes for which instances are persistent (saved to the PegaRULES database).

Data-A

Class	Description
Data-Address-Email	Stores email addresses used in correspondence. Can be referenced in Correspondence Type rules.
Data-Address-Fax	Stores fax number addresses used in correspondence. Can be referenced in Correspondence Type rules.
Data-Address-PhoneText	Stores phone text messages used in correspondence. Can be referenced in Correspondence Type rules.
Data-Address-Postal	Stores street addresses used in correspondence. Can be referenced in Correspondence Type rules.
Data-Admin-ArchiveSettings	Supports the Purge/Archive wizard.
Data-Admin-IS-ClientSimulation	Supports unit testing of service rules with the Run toolbar button.
Data-Admin-Product	Stores information used by Product rule processing during upload.
Data-Admin-Products-Restore-	Supports hotfix installation and backout.
Data-Admin-Security	Supports the Access Role Editor.
Data-Admin-Skill	Associates skill ratings with operators. Skill names are rules, not data objects.
Data-Admin-StartingFlows	Maintains the starting flows for a given access group and workpool, to support IWM and other facilities.
Data-Admin-SysMaint	Supports reporting features of the portal.
Data-Admin-System-AuthPolicies	Hold security policies entered though the Security Policy gadget. See Systems category — Settings page.
Data-Admin-Tenant	Stores tenant information in a multitenant system.
Data-Admin-UnavailablePeriod	Supports recording of periods when a user is unavailable, corresponding to dates entered in the Scheduled Absences array on the Availability tab of the Operator ID form.
Data-Agent	Saves the last time the agent was awakened.
Data-ApplicationDependency	Supports application import and export.
Data-Assignment-Summary	Supports reporting on assignments, through a database table pcv4_assignment_summary. If you create a custom table to hold work items (to supplement the standard table pc_work), you must adjust the database view definition. See Database views and PDN article How to customize the display of a worklist.
Data-Assignment-WBSummary	Supports reporting on assignments, through a database table pcv4_assignmentwb_summary. If you create a custom table to hold work items (to supplement the standard table pc_work), you must adjust the database view definition. See Database views.
Data-Assistant	Not used.
Data-AutoTest-AutoGen	Supports testing of decision tables; part of Automated Unit Testing. See About Automated Unit Testing.
Data-AutoTest-Result-Case	Holds results of tests; part of Automated Unit Testing. See About Automated Unit Testing.
Data-AutoTest-Result-Suite	Holds results of tests; part of Automated Unit Testing. See About Automated Unit Testing.

Data-C

Class	Description
Data-Circumstance-Duplicates	Supports problem reporting with rules that contain circumstanceproperties. Linked to a view in the PegaRULES database. See Database views.
Data-ConnectHTTPStatus	Supports runtime operations of Connect HTTP rules. About Connect HTTP rules.
Data-Corr-Email	Holds outgoing email correspondence. Can be referenced in Correspondence Type rules.
Data-Corr-Fax	Holds outgoing fax correspondence. Can be referenced in Correspondence Type rules.
Data-Corr-Letter	Holds the body of letter or fax correspondence. Can be referenced in Correspondence Type rules.
Data-Corr-PhoneText	Holds the body of phone text correspondence. Can be referenced in Correspondence Type rules.
Data-Cover-Associations	Not used.
Data-Customer	Deprecated. Use Data-Party-Person or Data-Party-Org.

Data-D to Data-O

Data-DBSummary-RDBList	Referenced in the RDB-List method for reports.
Data-DBSummary-Union	Not used.
Data-DecisionLogicSupport	Supports decision rule form processing.
Data-DecisionRulePath	Supports decision rule form processing.
Data-DisplayProperties	Abstract. Supports harness operations.
Data-EmailAttachments	Supports creation of outgoing email attachments (as part of correspondence) from work item attachments.
Data-Email-Receive	Not used.
Data-Event-Pattern	Supports scheduled processing of Agent Schedule instances (Data-Agent-Queue).
Data-Find	Supports full-text search.
Data-Find-Results	Supports full-text search.
Data-Gadget	The Applies To class of activities that define the gadgets in the tabs of the portal. Referenced in portal rules. No instances.
Data-Inventory	Supports the Import wizard.
Data-IS-ClientSimulation	Supports interactive testing of service rules with the Run toolbar button.
Data-Management-Target	Supports the Product Migration wizard.
Data-MO	Reserved. Supports models for flows based on flow rule category.
Data-MO-Activity	Reserved. Supports models for flows based on flow rule category.
Data-MO-Connector	Reserved. Supports models for flows based on flow rule category.
Data-MO-Event	Reserved. Supports models for flows based on flow rule category.
Data-MO-Freeform	Reserved. Supports models for flows based on flow rule category.
Data-MO-Gateway	Reserved. Supports models for flows based on flow rule category.
Data-MOD	Reserved. Supports models for flows based on flow rule category.
Data-MQMessage	Contains WebSphere MQ messages created through operation of the Service MQ or Connect MQ interfaces.
Data-Optimization-Info	Supports the Process Optimizer.

Data-P to Data-R

Data-Parse-State	Supports Rule-Parse-Structured processing. See About Parse Structured rules.
Data-Party-Com	Used in work party configuration, generally for businesses that have a domain ending in ".com." Can be referenced in Work Parties rule instances. Contains the PartyDisplay HTML rule that can appear on the work item entry form. When users complete the party fields on a work item entry form that uses a Rule-Obj-WorkParties rule referencing this class, they create instances of this class.
Data-Party-Gov	Used in work party configuration. Can be referenced in Work Parties rule instances. Contains the PartyDisplay HTML rule that can appear on the work item entry form. When users complete the party fields on a work item entry form that uses a Rule-Obj-WorkParties rule referencing this class, they create instances of this class.
Data-Party-Operator	Used in party configuration. Can be referenced in Work Parties rule instances. Contains the PartyDisplay HTML rule that can appear on the work item entry form. When users complete the party fields on a work item entry form that uses a Rule-Obj-WorkParties rule referencing this class, they create instances of this class.
Data-Party-Org	Used in party configuration for nonprofit organizations. Can be referenced in Work Parties rule instances. Contains the PartyDisplay HTML rule that can appear on the work item entry form. When users complete the party fields on a work item entry form that uses a Rule-Obj-WorkParties rule referencing this class, they create instances of this class.
Data-Party-Person	Used in party configuration. Can be referenced in Work Parties rule instances. Contains the PartyDisplay HTML rule that can appear on the work item entry form. When users complete the party fields on a work item entry form that uses a Rule-Obj-WorkParties rule referencing this class, they create instances of this class.
Data-PerfTest	Used by the Performance Test utility to support performance benchmarking.
Data-Portal	Contains facts about your portal appearance and gadgets appearing on your portal.
Data-Project-Task	A data table that supports the project worklist. See About the Project Management communication link.
Data-Report-Aging	Contains data supporting aging reports.
Data-Report-Category	Supports the Report Browser display and interactions.
Data-Rule-ClassAncestor	Internal. Facilitates high-performance rule resolution.
Data-Report-Shortcut	Supports the Report Browser display and interactions.
Data-Rule-Locking	Supports reporting on checked-out rules, through the pcbv4_rule_lockingdatabase view.
Data-Rule-Overrides	Supports reporting through the prbv4_rule_overrides database view.
Data-Rule-Summary	Supports searching and reporting on rules through the pr4_rule_vw database view.  See Reporting on rules.
Data-RuleSearch	Supports the full-text search facilities. In a multinode system, uses Connect SOAP and Service SOAP rules. See Full text search.

Data-S to Data-W

Data-Saved-Context	Contains saved requestor contexts.
Data-Scan-Configuration	Retains scanner configuration details.
Data-SecurityVAUtility	Supports the Rule Security Analyzer.
Data-ServiceMessage	Used only passing service parameter data at run time, and by Service Email rules for attachments.
Data-ServiceSimulation	Supports testing of service rules with the Run button.
Data-Spellchecker	Supports spell-checking processing.
Data-SystemStart	Not used.
Data-TRACERSettings	Holds a user's settings for the Tracer tool.
Data-UI-Component-*	Internal classes supporting presentation of user forms derived from harnesses, sections, and flow actions.
Data-UniqueID	Stores the next available unique work object or other ID number.
Data-Upgrade	Reserved. Used internally only.
Data-VERB-Registry	Not used.
Data-VERB-Repository	Not used.
Data-Work-History	Supports reporting through the pcv4_work_history database view.
Data-Work-Summary	Supports advanced reporting about work items using full-text search indexes or other custom searches. See Full text search.
Data-WorkAttach-ECM	Class of work item file attachments that are saved in an external CMIS system, rather than in the PegaRULES database.
Data-WorkAttach-File	Contains files attached to work objects, unless such attachments are stored in an external CMIS system.
Data-WorkAttach-Note	Contains text notes attached to work objects.
Data-WorkAttach-ScanDocument	Contains scanned documents (TIFF images) attached to a work item. See About Pega Document Scanning.
Data-WorkAttach-ScreenShot	Contains Screen Shot image attachments to a work item.
Data-WorkAttach-URL	Contains URL attachments to a work object.

class name prefix

A class name prefix is used during pattern inheritance when the Pega 7 Platform searches the classstructure to find a rule using a sequence of prefixes of the class name. The hyphen delimits segments of the name.

Class layers

Classes define the applicability, or scope, of a rule instance. Knowledge of the different layers of classes and their inheritance relationships is important as you develop applications.

Framework classes

Framework classes define a common work-processing foundation that you extend and modify as implementation applications for an organization, division, or organization unit. Framework classes belong to the framework layer.

For example, the MyCo enterprise makes auto loans and has an auto loan framework application that contains all of the assets needed for the basic auto loan process. Then, the MyCo enterprise develops two implementations built on the auto loan framework to meet the specific requirements of its two divisions: a commercial business line and a personal line.

Using the New Application wizard, you can build a new implementation application and its implementation classes on a framework application. You can reuse some or all of the work and data class structure of the framework. From the new implementation application, you can use the Designer Studio landing pages, explorers, rule forms, and reports to reuse many of the rules and data objects inherited from the built-on framework layer. For example, while developing a process, you can select specifications or processes in a framework ruleset for reuse or customization in the current application.

When you build an implementation application, you can also create a reusable framework application built on the same framework. You can extend the framework so that it is used by other implementations that you might create later. As a best practice, reuse framework rules and create only specialized rules in your implementation application. For example, use report definitions in the framework classes that run with the corresponding implementation classes.

Note: Framework classes are different from Strategic Applications, which are starter applications for specific industries or lines of business.

Implementation classes

Implementation classes define the extension, reuse, and specialization of assets in a framework layer to meet the business requirements of an organization, division, or organization unit. For example, you can build two division-level implementations—business auto loan and personal auto loan—on an organization's auto loan framework layer.

Implementation classes belong to the implementation layer. Typically, cases that are related to application processes are instances of case type classes that belong only to the implementation layer.

Organization classes

Organization classes contain enterprise-wide data assets and assets that must be reused for business logic. Data assets include classes and rules for data stored in the system, and classes and rules for access to data in external systems by using connectors. Business logic assets include standard properties, decision tables, and service-level agreements.

For example, the MyCo enterprise might want to reuse, on an enterprise-wide basis, the property for employee serial number. By reusing this property, the various applications across the enterprise that an employee uses can consistently rely on the same serial number property for the same employee.

Organization classes belong to the organizational layer. In most configurations, your implementation and framework layers inherit (by pattern inheritance) from organization classes.

Tip: To identify the inheritance relationships among these classes, you can right-click the class name in the Application Explorer and select the Inheritance option.