PowerBuilder Foundation Class: A Service Orientated Framework

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PowerBuilder Foundation ClassA Service
Orientated Framework

• Sea Bass Software Limited
• www.seabass.co.uk

2
Introduction

• David Hargreaves
• david.hargreaves_at_seabass.co.uk
• Sea Bass Software Limited
• www.seabass.co.uk

3
Topics for Discussion

• PFC Architecture
• Using PFC Services
• Adding Additional Services

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PFC Architecture

• Evolution of Frameworks
• Service Orientated Framework

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Evolution of Frameworks

• General Purpose Framework
• Nest Generalisation Framework
• Service Orientated Framework

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General Purpose Framework

• All functionality in one ancestor
• Turn functionality on using functions
• Functionality provided through instance variables

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General Purpose Framework
Ancestor Window
boolean ib_sort FALSE boolean ib_filter FALSE
...
of_SetSort(TRUE) of_SetFilter(TRUE) ...
IF ib_sort THEN Sort code END IF IF ib_filter
THEN Filter code END IF
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Nested Generalisation Framework

• Ancestor class contains generic functionality
• Descendent classes add specific functionality
• Functionality enabled by selecting required
  descendant

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Nested Generalisation Framework
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Service Orientated Framework

• Functionality is encapsulated in service classes
• Requestor classes delegate work to service
  classes
• Uses the Client/Server model

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Service Orientated Framework
Services
Requestor
Base
Sort
Filter
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PFC Architecture Summary

• Code is encapsulated in service classes
• Requestor calls services when required
• Smaller hierarchy
• Maintenance is easier
• Quicker compilation time
• No duplication of code
• High level of reuse

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Using PFC Services

• Service Classes
• Requestor Classes
• Creating Services
• Delegating Work to Services

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Service Classes

• Perform work specific to the service
• Maintains a link to the requestor object

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Service Classes
n_cst_dwsrv_sort
u_dw idw_requestor ...
of_SetRequestor(u_dw adw_requestor) idw_requestor
adw_requestor ...
pfc_clicked(xpos, ypos, row, dwo) This.of_Sort()
...
of_Sort() idw_requestor.Sort() ...
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Requestor Classes

• Owns service objects
• Create service objects required
• Maintains a link to the service object
• Delegates work to the service object
• Destroys the service object

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Requestor Classes
u_dw
n_cst_dwsrv_sort inv_sort ...
of_SetSort(boolean ab_switch) inv_sort Create
n_cst_dwsrv_sort inv_sort.of_SetRequestor(This)
...
clicked(xpos, ypos, row, dwo) IF IsValid
(inv_Sort) THEN inv_Sort.Event pfc_clicked
( xpos, ypos, row, dwo ) END IF ...
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Creating Services

• Requestor object owns the service object
• Requestor object creates the service (two way
  link)
• Requestor contains pre-defined instance variables
  to point to service
• Pre-defined requestor functions allowing the
  service to be created

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Creating Services
u_dw (requestor)
n_cst_dwsrv_sort inv_sort
... of_SetSort(TRUE) inv_sort Create
n_cst_dwsvr_sort inv_sort.of_SetRequestor(This)
...
n_cst_dwsvr_sort (service)
u_dw idw_requestor
... idw_requestor adw_requestor ...
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Demonstration

• Create the default sort service
• Create the default filter service

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Delegating Work to Services

• Work is delegated using pre-defined methods in
  Requestor and Service objects
• Delegation Types
• Pre-defined delegation
• User-defined delegation

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Pre-defined Delegation

• Requestor Pre-coded events
• PowerBuilder events
• PFC events called from menu
• Service Pre-coded events
• Re-directed from requestor

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Pre-defined Delegation
u_dw (requestor)
n_cst_dwsrv_sort inv_sort
IF IsValid (inv_Sort) THEN inv_Sort.Event
pfc_clicked ( xpos, ypos, row, dwo ) END IF
n_cst_dwsvr_sort (service)
u_dw idw_requestor
... idw_Requestor.Sort() ...
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User-defined Delegation

• Service pre-coded functions
• Requestor delegates work to service
• Used to change the state of a service

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User-defined Delegation
u_dw (requestor)
n_cst_dwsrv_sort inv_sort
This.of_SetSort(TRUE) IF IsValid(inv_Sort)
THEN inv_Sort.of_SetStyle(inv_sort.dragdrop) END
IF
n_cst_dwsvr_sort (service)
integer ii_style
... ii_style ai_style ... Return 1
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Demonstration

• Assign the DRAGDROP style to the sort service
• Assign the EXTENDED style to the filter service
• Create the calendar service on the joining date
• Create the calculator service on the salary

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Using PFC Services Summary

• Service Classes encapsulate functionality
• Requestor Classes call required services
• Pre-defined delegation has been coded into the
  PFC
• User-defined delegation changes the default style
  of the service

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Adding Additional Services

• Create Additional Service Objects
• Create Service Object
• Instance variables
• Functions
• Events
• Add New Service to Requestor
• Instance variable
• Create/Destroy function
• Re-direct calls to service

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Create Additional Service Objects
pfc_w_master
pfc_n_base
w_master
n_base
pfc_w_response
pfc_n_cst_dwsrv
w_response
n_cst_dwsrv
w_column_dragdrop
n_cst_dwsrv_column
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Demonstration

• Create a DataWindow service to allow columns to
  be moved during runtime
• Create a column service object
• Create a column service attribute object
• Create a column drag and drop window

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Create Service Functions

• Encapsulate functionality
• Protected instance variables
• Protected functions
• Enable the requestor to customise the service
• Protected instance variables
• Public functions to change variables

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Create Service Functions
n_cst_dwsrv_column (Extension Layer)
string is_excludecolumns
Public of_setexclude (string as_excludecols) of
_getexclude (ref string as_excludecols) Protect
ed of_buildcolumnattrib ( ref
n_cst_columnattrib anv_columnattrib) ...
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Demonstration

• Create the column service functionality
• Create the required instance variables
• Create the public interface, such as get/set
  functions
• Create the column functionality

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Create Service Events

• Create user events for requestor redirection
• Process service functionality
• Call additional service objects
• Ensure a return code is provided

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Create Service Events
n_cst_dwsrv_column (Extension Layer)
event pfc_column()
... IF NOT IsValid(idw_requestor) THEN li_rc
-1 ELSE li_rc This.of_SetColumn() END
IF RETURN li_rc
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Demonstration

• Create the column service events
• Create a pfc_columndlg event to call the
  drag-drop window

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Add New Service to Requestor

• Add instance variable for service
• Add of_Set() function to enable service
• Re-direct events to service

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Add New Service to Requestor
u_dw (Extension Layer)
n_cst_dwsrv_column inv_column ...
Public of_setcolumn(boolean ab_switch)
pfc_columndlg event IF IsValid(inv_column)
THEN inv_column.Event pfc_columndlg() END IF ...
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Demonstration

• Create the requestor service calls
• Create service instance variable
• Create function to turn service on/off
• Create a pfc_columndlg event to call the column
  service

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Creating Services

• Requestor object owns the service object
• Requestor object creates the service (two way
  link)
• Requestor contains pre-defined instance variables
  to point to service
• Pre-defined requestor functions allowing the
  service to be created

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Creating Services
u_dw (requestor)
n_cst_dwsrv_column inv_column
... of_SetColumn(TRUE) inv_column Create
n_cst_dwsvr_column inv_column.of_SetRequestor(Thi
s) ...
n_cst_dwsvr_column (service)
u_dw idw_requestor
... idw_requestor adw_requestor ...
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Demonstration

• Create the column service to allow columns to be
  moved during runtime
• Add a button to call the service

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Adding Additional Services Summary

• Create new service objects
• Create events for redirection and functions to
  encapsulate functionality
• Create requestor links to service object
• Instance variable
• Create/Destroy function
• Re-direct functionality

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Questions and Answers

• David Hargreaves
• david.hargreaves_at_seabass.co.uk
• Sarah Bell - Business Manager
• sarah.bell_at_seabass.co.uk
• [phone]
• Web Site
• www.seabass.co.uk