ARCH-7: A Class-Based Implementation of the OpenEdge ® Reference Architecture John Sadd Fellow and...

ARCH-7: A Class-Based Implementation of the OpenEdge® Reference Architecture

John SaddFellow and OpenEdge Evangelist

Applied Technology

© 2007 Progress Software Corporation2 ARCH-7: A Class-based Implementation of the OERA

Goals for the session

Show practical implications of the OpenEdge Reference Architecture

Show how ABL support for classes is useful Discuss some interesting issues and choices


Agenda

OERA for SOBA and existing materials Overview of a class-based approach Server-side components Bridging the gap from client to server Using Templates Introducing Managers The Context Helper Class Generating Components from OE Architect Relational data in classes


OpenEdge Reference ArchitectureFor Service Oriented Business Applications

Design for longevity, flexibility, and competitive advantage

Accommodates evolving business requirements

Anticipates trends in technology

Provides agile and flexible architecture

PresentationPresentation

Business ComponentsBusiness Components

Data AccessData Access

Data SourcesData Sources

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Infrastru

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Enterprise ServicesEnterprise Services


Basic Architecture Principles

Avoid duplicated code!• “ABL is a great language – we want you to write

less of it.”

• Do every job once and only once.

• Outlaw Copy-Paste-Edit!

• Factor! Factor! Factor!

Don’t hardwire things that are liable to change!• That’s what the OERA layers are there for…


Implementing the OpenEdge Reference Architecture on PSDN


For example: Business Entities using Procedures

Server BE procs

dsOrder.i

{etOrder.i}

{etOrderLine.i}

{etItem.i}

DEFINE DATASET…

Data Access Object

SUPER

SUPER

Template procedures Include files Super procedures RUN VALUE (…)

Business Entity

beOrder.p

beEntity.i

RUN daOrder.p

PROC fetchWhere:

…

Super Procedure

beSupport.p

beOrderValidate.p

(optional)

eOrderLineModifyPreTrans:


Agenda



Basic principles of using classes in ABL

Strong typing• Compiler knows exactly what everything is

• Compiler cross-checks classes

• Much more robust error checking at compile time

Inheritance of common behavior• Definitional, not done at runtime

• Compiler checking of validity

• Always invoke the most-derived version


Overview of server-side classes


Top-level class componentbase.cls

CLASS base.componentbase IMPLEMENTS interfaces.iComponent:/* Base class for all objects. Locates the service manager, which it expects some startup routine to have created.*/ DEFINE PROTECTED PROPERTY servicemgr AS service.servicemgr NO-UNDO GET. PRIVATE SET. CONSTRUCTOR PROTECTED componentbase(): DEFINE VARIABLE sessionObject AS progress.lang.object. sessionObject = SESSION:FIRST-OBJECT. DO WHILE VALID-OBJECT(sessionObject) AND sessionObject:GetClass():TypeName <> 'service.servicemgr': sessionObject = sessionObject:NEXT-SIBLING. END. IF NOT VALID-OBJECT(sessionObject) THEN FatalError( "Session management service not found!"). ELSE servicemgr = CAST (sessionObject, service.servicemgr). END CONSTRUCTOR. METHOD PUBLIC VOID FatalError (pcMessage AS CHAR): MESSAGE "Fatal error!" SKIP pcMessage VIEW-AS ALERT-BOX ERROR. END.


The CLASS statement

The CLASS statement identifies the class by name and by package to the compiler

If it INHERITS another class this is named If it IMPLEMENTS an interface this is named

CLASS base.componentbase IMPLEMENTS interfaces.iComponent:

INTERFACE interfaces.icomponent: METHOD PUBLIC VOID initializeComponent(). METHOD PUBLIC VOID destroyComponent().END INTERFACE.


Data members and properties

Data members in a class can be PUBLIC, PROTECTED, or PRIVATE

The data type can be a class type For added control you can define data as

properties• GET phrase controls read access and behavior• SET phrase controls write access and behavior

DEFINE PROTECTED PROPERTY servicemgr AS service.servicemgr NO-UNDO GET. PRIVATE SET.


Constructors and destructors in classes

The CONSTRUCTOR represents the “main block” code

It can have parameters but no return type It can be inherited and overridden

CONSTRUCTOR PROTECTED componentbase():

…

END CONSTRUCTOR

The DESTRUCTOR represents the code to execute when the object is deleted

It has no parameters and no return type It is reliably invoked unless the whole session

ends unexpectedly


The object hierarchy

CONSTRUCTOR code locates the service manager

DEFINE VARIABLE sessionObject AS progress.lang.object.

sessionObject = SESSION:FIRST-OBJECT. DO WHILE VALID-OBJECT(sessionObject) AND sessionObject:GetClass():TypeName <> 'service.servicemgr': sessionObject = sessionObject:NEXT-SIBLING. END. IF NOT VALID-OBJECT(sessionObject) THEN FatalError( "Session management service not found!"). ELSE servicemgr = CAST (sessionObject, service.servicemgr).

progress.lang.object

service.servicemgr

sessionObject

servicemgr

CAST

DEFINE PROTECTED PROPERTY servicemgr AS service.servicemgr NO-UNDO GET. PRIVATE SET.


Methods in classes

Methods take the place of internal procedures and functions

They define parameters and a return type like functions do

VOID means there’s no return type Like data members, they are PUBLIC,

PROTECTED, or PRIVATE

METHOD PUBLIC VOID FatalError (pcMessage AS CHAR): MESSAGE "Fatal error!" SKIP pcMessage VIEW-AS ALERT-BOX ERROR. END.


Agenda



Business Entities and Data Access Objects


Business Component classes

CLASS base.businesscomponent INHERITS base.componentbase:

CLASS base.businessentity INHERITS base.businesscomponent IMPLEMENTS interfaces.ibusinessentity: DEFINE PROTECTED VARIABLE dataAccess AS base.dataaccessobject.

METHOD fetchData(): dataAccess:loadData().

CLASS samples.beCustomer INHERITS base.businessentity: {samples/dsCustomer.i} CONSTRUCTOR PUBLIC beCustomer (): dataAccess = CAST (servicemgr:startService (‘samples.daCustomer',"da"), samples.daCustomer). END CONSTRUCTOR. METHOD PUBLIC OVERRIDE VOID validateData(): SUPER:validateData(). validateCustomer(INPUT-OUTPUT DATASET-HANDLE hdsDataset BY-REFERENCE). END METHOD. METHOD PRIVATE VOID validateCustomer(INPUT-OUTPUT DATASET dsCustomer):…


Data Access classes

CLASS base.dataaccess INHERITS base.componentbase:

CLASS base.dataaccessobject INHERITS base.dataaccess IMPLEMENTS interfaces.idataaccess:…METHOD PUBLIC VOID loadData(): hdsDataset:EMPTY-DATASET(). setFillMode('MERGE':U). attachDatasource(). fillDataset(). detachDatasource(). END METHOD.

CLASS samples.daCustomer INHERITS base.dataaccessobject: {samples/dsCustomer.i &REFERENCE-ONLY=REFERENCE-ONLY} METHOD PUBLIC OVERRIDE VOID attachDatasource(): bufferDatasource('ttCustomer', 'Customer', 'CustNum', '', 'FOR EACH Customer'). END METHOD.


Agenda



OpenEdge Reference Architecture:How do you invoke a Business Component?





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Enterprise ServicesEnterprise ServicesClient session

AppServer™ session


Principles for making calls to the AppServer

You can run a procedure on an AppServer You can run an internal procedure, but only by

binding the AppServer session first• Binding the AppServer is not a good idea• This also requires multiple calls to complete a

single request You want the AppServer to be stateless You cannot instantiate a class on the AppServer You don’t want clients directly calling Business

Component classes anyway! So: Define a procedure on the server to handle a

specific request for a specific Business Component type


The Service Adapter and Service Interface





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Enterprise ServicesEnterprise ServicesClient session

AppServer session

Service AdapterService Adapter

Service InterfaceService Interface


The role of the Service Adapter

You don’t want client objects knowing the details about Business Components• Where they’re located

• Exactly what their APIs are

• How to route a request to them

The Service Adapter provides a key layer of indirection and discovery


The role of the Service Interface

Defines a point of entry for each accessible method in each Business Component

Static parameters for those methods so they are self-describing

Common services invoked consistently and automatically• Authentication, security, context…

So you want client Service Adapters calling Service Interface procedures!


The Service Adapter class on the client

CLASS pres.serviceadapter INHERITS base.componentbase: CONSTRUCTOR PUBLIC serviceadapter(): hAppServer = IF VALID-HANDLE(SESSION:FIRST-SERVER) THEN SESSION:FIRST-SERVER ELSE SESSION:HANDLE. END CONSTRUCTOR.

METHOD PUBLIC VOID fetchData (OUTPUT DATASET-HANDLE dsDataset): RUN VALUE(getSIPath() + "_fetchdata.p") ON hAppServer (OUTPUT DATASET-HANDLE dsDataset). END METHOD.

METHOD PROTECTED CHARACTER getSIPath (): RETURN ?. END METHOD.END CLASS.

CLASS samples.pres.saCustomer INHERITS pres.serviceadapter: METHOD PROTECTED OVERRIDE CHARACTER getSIPath(): RETURN “samples/api/beCustomer". END METHOD.END CLASS.


The Service Interface procedure on the server

/* becustomer_fetchdata.p */ &SCOPED-DEFINE PACKAGE-NAME samples &SCOPED-DEFINE COMPONENT-NAME customer &SCOPED-DEFINE METHOD-NAME fetchData &SCOPED-DEFINE PARAM-LIST {templates/fetchdata_params.i} &SCOPED-DEFINE PREFIX-NAME be &SCOPED-DEFINE DATASET-MODE OUTPUT {templates/apicode.i}

servicemgr:sessionContextService:setContextId(pcContextId).authenticationService = servicemgr:authenticationService.authenticationService:loadPrincipal().

{&PREFIX-NAME}{&COMPONENT-NAME} = CAST (servicemgr:startService ('{&PACKAGE-NAME}.{&PREFIX-NAME}{&COMPONENT-NAME}', "{&PREFIX-NAME}"), {&PACKAGE-NAME}.{&PREFIX-NAME}{&COMPONENT-NAME}). {&PREFIX-NAME}{&COMPONENT-NAME}:{&METHOD-NAME}({&PARAM-LIST}).


Agenda



Repeatable elements in an application

Service Adapter

class

Service Interface

procedureBusiness Entity

class

Data Access Object

class

Data Source Object

class


Business Entity class template

/*---------------------------------------------------------------------File : be<entity-name>.clsPurpose : Generated from the template for Business Entity classes Description : Sample Business Entity for <entity-name> Edited : April 2007 ---------------------------------------------------------------------*/ CLASS <package-name>.be<entity-name> INHERITS base.businessentity: {<package-name>/ds<entity-name>.i &REFERENCE-ONLY=REFERENCE-ONLY} CONSTRUCTOR PUBLIC be<entity-name>(): dataAccess = CAST (servicemgr:startService (‘<package-name>.da<entity-name>', "da"), <package-name>.da<entity-name> ). END CONSTRUCTOR.…END CLASS.


List of preprocessors and other values

PACKAGE-NAME ENTITY-NAME (or COMPONENT-NAME) PREFIX-NAME (e.g., ‘be’) For Data-Sources:

• Temp-table name• Database table list• (Optional) database key field list• Field mapping between physical and logical• Base DB query (‘FOR EACH <table-name>’)


Business Entity with the blanks filled in

/*---------------------------------------------------------------------File : beCustOrder.clsPurpose : Generated from the template for Business Entity classes Description : Sample Business Entity for CustOrderEdited : 04/04/07 ---------------------------------------------------------------------*/ CLASS Sports2000.CustOrder.beCustOrder INHERITS base.businessentity: {Sports2000.CustOrder/dsCustOrder.i &REFERENCE-ONLY=REFERENCE-ONLY} CONSTRUCTOR PUBLIC beCustOrder(): dataAccess = CAST (servicemgr:startService ('Sports2000.CustOrder.daCustOrder',"da"), Sports2000.CustOrder.daCustOrder). END CONSTRUCTOR.…END CLASS.


Agenda



OpenEdge Reference ArchitectureCommon Infrastructure





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Enterprise ServicesEnterprise Services Core Services• Auditing…

ABL Managers• Authorization

• Context Management


The Service Manager


The role of the Service Manager

CLASS service.servicemgr INHERITS base.manager IMPLEMENTS interfaces.iservicemgr, interfaces.icomponent:

DEFINE TEMP-TABLE ttSessionComponent NO-UNDO FIELD ComponentName AS CHARACTER FIELD ComponentType AS CHARACTER FIELD ComponentRef AS progress.lang.object FIELD SINGLETON AS LOGICAL. …METHOD PUBLIC progress.lang.object startService (pcComponentName AS CHARACTER, pcComponentType AS CHARACTER):

FIND FIRST ttSessionComponent WHERE ttSessionComponent.ComponentName = pcComponentName AND ttSessionComponent.ComponentType = pcComponentType NO-LOCK NO-ERROR. IF NOT AVAILABLE ttSessionComponent OR NOT ttSessionComponent.SINGLETON THEN RUN VALUE(cPackage + '/factory.p') (cClass, OUTPUT oObject, OUTPUT lSingleton NO-ERROR. RETURN (IF AVAILABLE ttSessionComponent THEN ttSessionComponent.ComponentRef ELSE ?). END METHOD.END CLASS.


Invoking Business Component Instances

Service

Manager

Service Interface

procedure

Business Component

class

Service Adapter

class


The role of the factory

/* samples/factory.p */DEFINE INPUT PARAMETER pcObject AS CHARACTER NO-UNDO.DEFINE OUTPUT PARAMETER objInstance AS progress.lang.object NO-UNDO.DEFINE OUTPUT PARAMETER plSingleton AS LOGICAL NO-UNDO.

CASE pcObject: WHEN 'becustomer' THEN DO: objInstance = NEW samples.becustomer(). plSingleton = YES. END. WHEN 'dacustomer' THEN DO: objInstance = NEW samples.dacustomer(). plSingleton = YES. END.END CASE.

You can’t create a class instance dynamically the way you can with RUN VALUE(…)• The compiler insists on knowing what’s going on!

The factory has a case for each possible object to create• Organized by package and object type


Using a factory procedure

Service

Manager

Service Interface

procedure

Business Component

class

Factory

procedure

Service Adapter

class


Alert! Planned (but of course not official) for 10.1C:

Service

Manager

Service Interface

procedure

Business Component

class

Service Adapter

class

DYNAMIC-NEW language extension will allow the Service Manager to instantiate classes directly using an expression for the class name.


Agenda



Types of Context and State Information

Global context Application service context Client connection context

• These types can be persisted by a context manager

Client request context• This is transient information

• Does not need to be stored persistently


The context helper class

A complete implementation will have a context manager as Common Infrastructure• This can persist context for a session, for a

user, for the entire application

This implementation uses a context helper class to manage transient state information• This information is passed between client and

server as a context ProDataSet


ABL programming issues for the context class

The context class manages a ProDataSet instance and supporting methods

But you can’t pass an object (class instance) to the AppServer, only data

Therefore you have to extract the data and pass it to another object on the other side


Context helper class flow

Client Service Requester cltdatacontext.cls

DATASET dsContext

Service Adapter

Service Interface

srvdatacontext.cls

DATASET dsContext REF-ONLY

DATASET-HANDLE

from client

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5

6

7

Create client context instance

Populate data Extract data Pass DataSet to

Service Adapter Pass to Service

Interface Create server

context instance Bind context to

DataSet passed from client

setContext


Agenda



Using the DataSet builder to generate data for a custom tool to use


Getting database data instead of an XMI file


Extending the OE Architect Menus


Generating Component source files


Code generation sample: the template

/*---------------------------------------------------------------------File : be<entity-name>.clsPurpose : Generated from the template for Business Entity classes Description : Sample Business Entity for <entity-name> Edited : April 2007 ---------------------------------------------------------------------*/ CLASS <package-name>.be<entity-name> INHERITS base.businessentity: {<package-name>/ds<entity-name>.i &REFERENCE-ONLY=REFERENCE-ONLY} CONSTRUCTOR PUBLIC be<entity-name>(): dataAccess = CAST (servicemgr:startService (‘<package-name>.da<entity-name>', "da"), <package-name>.da<entity-name> ). END CONSTRUCTOR.…END CLASS.


Code generation sample – the result

/*---------------------------------------------------------------------File : beCustOrder.clsPurpose : Generated from the template for Business Entity classes Description : Sample Business Entity for CustOrderEdited : 04/04/07 ---------------------------------------------------------------------*/ CLASS Sports2000.CustOrder.beCustOrder INHERITS base.businessentity: {Sports2000.CustOrder/dsCustOrder.i &REFERENCE-ONLY=REFERENCE-ONLY} CONSTRUCTOR PUBLIC beCustOrder(): dataAccess = CAST (servicemgr:startService ('Sports2000.CustOrder.daCustOrder',"da"), Sports2000.CustOrder.daCustOrder). END CONSTRUCTOR.…END CLASS.


A live look at generating components from templates using OpenEdge Architect

Tools for Business Logic


In Summary

The layers of the OpenEdge Reference Architecture provide valuable structure that you can fill in without excessive effort• Using templates for standard component types

• Using general-purpose supporting code

Classes in ABL can help you define your structure and assure its integrity

Resolve design issues in ways appropriate to your needs


For More Information, go to…

PSDN – OE Principles• http://www.psdn.com/library/kbcategory.jspa?categoryID=230

Other Exchange sessions• ARCH-11: Building a Presentation Layer with Classes

• ARCH-5: Modeling with UML

• ARCH-12: Design Patterns

• ARCH-2: OERA Latest Thinking

• DEV-12: Object-Oriented Programming in ABL


Questions?


Thank you for your time!


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ARCH-7: A Class-Based Implementation of the OpenEdge ® Reference Architecture John Sadd Fellow and...

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