Object-oriented%20programming%20with%20OpenEdge

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Object-oriented programming with OpenEdge 10.1A

• PSDN Web Seminar
• February 2006

Salvador Viñals
Consultant Product Manager Progress Software
OpenEdge Division
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Audience

• Technical level Intermediate
• This session is targeted to customers somewhat
  familiar with object-orientation
• This session does not focus on reference
  information

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OpenEdge 10.1A Focus

• Improve the productivity of OpenEdge
• to provide our partners significant competitive
  advantage through the software they develop and
  deploy

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OpenEdge 10.1A Highlights
What we are not going to talk about today

• OpenEdge Architect
• Auditing
• Language short-hand syntax (), READ-XML(),
  WRITE-XML(), BY-REFERENCE, XP manifests, 64bit
  r-code
• RDBMS performance, more online utilities and
  schema changes
• JDBC Type 4
• Symbiotic Adapter for SonicMQ
• Install Simpler, faster and embeddable
• Rebranding Fathom to OpenEdge
• Replication Enable online, AI, single command
  failback
• DVD
• Linux 64bit (RH AS 3, SuSe 9) . and much
  more

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Agenda

• Object-orientation in OpenEdge 10.1A
• Benefits
• Positioning
• Concepts and Features
• Object-oriented programming
• Where to go next

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Introducing OO in 10.1A
OpenEdge 10.1 introduces formal object-oriented
programming through language extensions that
support user-defined classes. User-defined
classes allow you to define objects, with methods
and data, and interfaces for building business
applications.
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Object-orientation Benefits

• Lets you organize applications the way you
  think
• around objects
• Increase application robustness (strong typing)
• More development productivity with encapsulation,
  inheritance, and polymorphism
• Promotes reusability
• Helps you build OERA. More closely support SOA
• Modular. Components. Composite applications.
• Service contracts Interfaces
• Ease application maintenance
• Natural integration with
• modeling tools
• other OO platforms
• Ease hire new developers

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Positioning

• When shall you consider using Classes?
• For well defined and designed functional units
• Not too coarse. Not too granular.
• Useful (and easy) when called from at least three
  different modules of the application, or
  different applications
• Need to adhere to Interfaces
• When Procedures are best?
• Tasks
• Processes
• Workflows
• Dynamic or late bound code (not strong typed)
• Disposable programs

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Quick facts

• Multiple rollout strategy OpenEdge 10.1A is the
  first one
• The object-oriented extensions do not replace
  existing language constructs
• You do not need to use OO if you do not want
• Classes can include ON lteventgt constructs
• 10.1A language compiler is two-pass

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InteroperabilityProcedures and Classes

• Procedures
• Can NEW a CLASS
• Can DELETE an object
• Invoke methods using object reference
• Can pass object reference as a parameter
• Classes
• Can RUN a procedure
• Can invoke internal procedure / UDF using
  procedure handle

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Similarities betweenClasses and Procedures
Procedures Classes
Procedure files (.p) Class files (.cls)
Define variables Data members
Internal procedures VOID methods
User defined functions Other methods
Code in main block Constructor
Super-procedures Inheritance

.p
.cls
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Object-Oriented Concepts Overview
What do you need to understand to use OO?

• OO terminology for familiar concepts
• Classes, data members, methods, types objects
• Encapsulation
• Grouping data behavior together
• Inheritance
• Re-using and extending code
• Delegation
• Letting contained objects do their own work
• Interfaces
• Implementing a standard set of methods
• Polymorphism
• Generic code for objects with common data
  behavior

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OO in the 10.1A Features

• CLASS definitions
• Single inheritance hierarchies
• Data members and methods
• Interfaces
• Polymorphism
• Delegation
• CAST function
• VALID-OBJECT() method
• .cls files
• Support with development tools

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Details on Object-Oriented Concepts Overview and
10.1A Features

• Refer to the following 10.1A Beta program
  presentations that will be made available on PSDN
  along with this Web seminar
• (beta) Object-oriented programming in the
  Progress 4GL 10 1A1B Webinar.ppt
• (beta) Object-oriented programming in the
  Progress 4GL 10 1A2B Webinar.ppt

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Agenda

• Object-orientation in OpenEdge 10.1A
• Benefits
• Positioning
• Concepts and Features
• Object-oriented programming
• Where to go next

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Object-oriented programming

• When shall you consider using Classes?
• For well defined and designed functional units
• Not too coarse. Not too granular.
• Useful (and easy) when called from at least three
  different modules of the application, or
  different applications
• Need to adhere to Interfaces
• How to start?
• You need a model (white-board models are good)
• Best not to start with the presentation layer
• Best not to start with the data management layer
• Start inside-out
• Model the required functionality
• Identify potential functional units candidates
  for classes

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Object-oriented programming

• Logical model - Abstraction
• Identify Classes. Data members. Methods.
• Identify inheritance chains
• Identify interfaces you need to conform to
• Identify where youll need delegation,
  polymorphism, etc.
• Refine Too coarse? Too fine grained? Will you
  use it?
• Implementation model
• Define each of above
• Refine as needed
• Start programming

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Object-oriented programming

• Logical model - Abstraction
• Identify Classes. Data members. Methods.
• Identify inheritance chains
• Identify interfaces you need to conform to
• Identify where youll need delegation,
  polymorphism, etc.
• Refine Too coarse? Too fine grained? Reusable?
• Implementation model
• Define each of above
• Refine as needed
• Start programming

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Business Abstraction

• What is an Order?
• Business Operations
• Approve
• Ship
• Check Inventory
• Data Operations
• Create
• Read
• Update
• Delete

• Order

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Higher Level Abstraction

• What is a Business Entity
• Tracks my business
• What do I do with a business entity
• Business Operation
• Security
• Auditing
• Delegate CRUD to Data Access in subclasses
• Create
• Read
• Update
• Delete

• Business Entity

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Example of Logical Model
Presentation Layer
Data Access
Integration

• Business Processing

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Example of More Detailed Logical Model
Data Members
Super Class
Protected
Methods
Interface
Inheritance
Private
Subclass
Public
Polymorphism
Delegation
Polymorphism
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Object-oriented programming

• Logical model - Abstraction
• Identify Classes. Data members. Methods.
• Identify inheritance chains
• Identify interfaces you need to conform to
• Identify where youll need delegation,
  polymorphism, etc.
• Refine Too coarse? Too fine grained? Reusable?
• Implementation model
• Define each of above
• Refine as needed
• Start programming

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Super Class Business Entity

• What does a Business Entity need to do for the
  application?
• Data Members
• daObject - Retrieve records
• lcBEXMLDataSet Stores records in XML to pass
  around
• Methods
• fetchWhere Select Records (Read)
• saveChanges Saves Changes (Create, Update,
  Delete)
• Note Example doesnt contain Security or
  Auditing but that could be defined here as well

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Super Class Business Entity
CLASS OOABL.BusinessEntity / data members
/ DEFINE PUBLIC VARIABLE lcBEXMLDataSet AS
LONGCHAR NO-UNDO. / methods / METHOD
PUBLIC LONGCHAR fetchWhere (INPUT cBEWhere AS
CHAR) END. / fetchWhere/ METHOD PUBLIC
VOID saveChanges () END. / saveChanges
/ END CLASS. /BusinessEntity Class/
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Inheritance Hierarchy Overview
Re-using and extending code

• Inheritance is used to abstract out common
  functionality data amongst similar classes
• Inheritance relationship means a sub-class
  inherits all data members methods from a super
  class
• Resulting sub-class may extend or change behavior
  by overriding methods of super class or add
  functionality by adding new methods to the
  sub-class

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Inheritance - An Example
super class
Inherits
subclass
Additional
Override
Additional
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Inheritance - An Example
CLASS OOABL.BEOrder INHERITS OOABL.BusinessEntity
ProDataSet/PrivateOrderTT.i
ProDataSet/PrivateDSOrder.i
CONSTRUCTOR PUBLIC BEOrder (OUTPUT lSuccess AS
LOGICAL) END CONSTRUCTOR. / constructor
BEOrder / DESTRUCTOR PUBLIC BEOrder ()
END DESTRUCTOR. / destructor BEOrder /
METHOD PUBLIC OVERRIDE LONGCHAR fetchWhere (INPUT
cBEWhere AS CHAR) END. / fetchWhere/
METHOD PUBLIC OVERRIDE VOID saveChanges()
END. / saveChanges / METHOD PUBLIC VOID
processOrder() END. / processOrder / END
CLASS. /BEOrder Class/
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Delegation Overview
Letting contained classes do their own work

• Delegation may be used when an object is built
  from other objects that are not in the class
  hierarchy
• The containing object forwards messages it cant
  handle to a contained object, called its delegate
• The containing object defines a stub for the
  message

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Delegation An Example

• Business entity object delegates the record
  retrieval to data access object

delegates
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Delegation - Using an Interface to Ensure an API
Animation walks through the code design
OrderMain.p / Defines a BEOrder variable / /
NEWs BEOrder / / calls BEOrder fetchWhere / /
Passes dataset back to UI /
implements
delegates
Delegate Class
Container Class
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Delegation An Example
(complete sample code in annotations)
CLASS OOABL.DAOrder INHERITS OOABL.DataObject
ProDataSet/PrivateOrderTT.i
ProDataSet/PrivateDSOrder.i CONSTRUCTOR
PUBLIC DAOrder () END CONSTRUCTOR. /
INHERITED METHODS OVERRIDE SECTION / METHOD
PUBLIC OVERRIDE VOID ConvertToDS () /
Uses default READ-XML behavior / DATASET
dsOrderREAD-XML ("LONGCHAR", lcXMLDATASET,
"EMPTY", ?, ?, ?). END. /END
ConvertToDS / METHOD PUBLIC
OVERRIDE VOID ConvertToXML() / Default
XML-WRITE to LONGCHAR / DATASET
dsOrderWRITE-XML ("LONGCHAR", / target-type /
lcXMLDATASET, / longchar /
TRUE, / formatted /
?, / encoding / ?, /
schema location / ?, / write
schema / ?). / minschema /
END. / end of ConvertToXML /
. . . / . . .
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Delegation An Example
(complete sample code in annotations)
. . . / . . .
METHOD PUBLIC OVERRIDE LONGCHAR selectRecords
() DEFINE VARIABLE hdsOrder AS HANDLE
NO-UNDO. DEFINE VARIABLE hEvents AS
HANDLE NO-UNDO. DEFINE VARIABLE iBuff
AS INTEGER NO-UNDO. DEFINE VARIABLE
hBuff AS HANDLE NO-UNDO.
DEFINE QUERY qOrder FOR Sports2000.Order,
Sports2000.Customer, Sports2000.SalesRep.
DEFINE DATA-SOURCE srcOrder FOR QUERY qOrder
Order KEYS (OrderNum), Customer KEYS (CustNum),
SalesRep KEYS (SalesRep). DEFINE
DATA-SOURCE srcOline FOR OrderLine.
hdsOrder DATASET dsOrderHANDLE. / Use
NEW SET-CALLBACK Method for THIS-OBJECT instead
of persistent proc / SetCallBacks(INPUT
hdsOrder). / Prepare the query
/ QUERY qOrderQUERY-PREPARE("FOR EACH
Order WHERE order.ordernum " (cWhere)
", FIRST Customer OF Order, FIRST SalesRep
OUTER-JOIN OF Order"). / Attach
datasources before fill / BUFFER
ttOrderATTACH-DATA-SOURCE(DATA-SOURCE
srcOrderHANDLE, "Customer.Name,CustName").
BUFFER ttOlineATTACH-DATA-SOURCE(DATA-SOURCE
srcOlineHANDLE).
hDSOrderFILL(). /Detach datasources
after fill / DO iBuff 1 TO DATASET
dsOrderNUM-BUFFERS DATASET
dsOrderGET-BUFFER-HANDLE(iBuff)DETACH-DATA-SOURC
E(). END.
convertToXML(). RETURN lcXMLDataSet. END.
/ selectRecords /
. . . / . . .
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Interfaces Overview
Implementing a standard set of methods

• An interface specifies a set of method prototypes
  which must be implemented by a class in order to
  claim support for the interface
• Reliably defines a common API supported by
  different classes
• Use an INTERFACE to ensure the API exists
• Similar to inheritance, except no default data to
  inherit no default implementation for the
  methods
• A class may implement zero or more interfaces

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Interface An Example
OOABL.dataObject xmlDataSet LONGCHAR
hDataSetHANDLE cWhereCHARACTER
DataObject() convertToDS()VOID
convertToXML()VOID setcWhere()VOID
getcWhere()CHAR setDataSource()VOID
selectRecords()LONGCHAR updateRecords()VOID
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Interface An Example
(all dataObject classes will implement this
interface)
INTERFACE OOABL.IDataAccess METHOD PUBLIC
VOID setcWhere(INPUT icWhere AS CHARACTER).
/ will set the where clause for record selection
/ METHOD PUBLIC CHAR getcWhere (). /
will get the where clause for record selection
/ METHOD PUBLIC VOID setDataSources(INPUT
cDataSources AS CHARACTER). /will
initialize the dataset's datasources /
METHOD PUBLIC LONGCHAR selectRecords(). /
will select object specific records /
METHOD PUBLIC VOID updateRecords(INPUT lcXML AS
LONGCHAR). / store create, updates, and
deletes to records / METHOD PUBLIC VOID
convertToDS (). METHOD PUBLIC VOID
convertToXML (). END INTERFACE. /IDataAccess /
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Polymorphism Overview
Treating similar objects generically

• Multiple classes can inherit from same super
  class
• Each can override behavior in super class
• Multiple implementations
• Different behavior
• Instances of classes derived from the same super
  class can be dealt with generically at runtime
• A message in the super class is dispatched to the
  corresponding method in a subclass
• Polymorphism means each subclass may respond to
  the same message in a different manner

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Polymorphism An Example
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Polymorphism An Example
(complete sample code in annotations)
CLASS OOABL.BEOrder INHERITS OOABL.BusinessEntity
. . .
CLASS OOABL.BEExternalOrder INHERITS
OOABL.BEOrder FINAL . . .
CLASS OOABL.BEInternalOrder INHERITS
OOABL.BEOrder FINAL . . .
/ ProcessOrderMain.p -- Main procedure for an
Order Dataset / DEFINE INPUT PARAMETER
lInternal AS LOGICAL NO-UNDO. DEFINE INPUT
PARAMETER piOrderNum AS INTEGER NO-UNDO. DEFINE
OUTPUT PARAMETER lProcessed AS LOGICAL
NO-UNDO. DEFINE VARIABLE myBEOrder AS CLASS
OOABL.BEOrder NO-UNDO. DEFINE VARIABLE lcXML AS
LONGCHAR NO-UNDO. DEFINE VARIABLE lSuccess AS
LOGICAL NO-UNDO. / Instantiate the right
subclass / IF lInternal THEN myBEOrder NEW
OOABL.BEInternalOrder(OUTPUT LSuccess). ELSE
myBEOrder NEW OOABL.BEExternalOrder(OUTPUT
lSuccess). / fetch the right order and
orderlines / lcXML myBEOrderfetchWhere(STRING(
piOrderNum)). myBEOrderprocessOrder(OUTPUT
lProcessed). DELETE OBJECT myBEOrder.
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Polymorphism Another Example
Director.p / Defines a Boss variable / / NEWs
Boss (RegionalManager or CorporateManager / /
sets Boss cTaskToDelegate / / calls Boss
delegateTask / / deletes Boss object etc. /
delegates
implements
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Where to go next
Product Documentation

• OpenEdge Getting Started Object-oriented
  Programming
• What's New in OpenEdge 10.1 Object Oriented
  Programming (April 2006)
• Article Object-orientation and the Progress ABL
  in OpenEdge Release 10.1A
• Development patterns web papers (coming up soon)

Education Course
PSDN
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Thank you for your time!
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Questions
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