This example illustrates the use of a Program to manage a domain download into a control system as depicted in Figure A.1. The download requires the segmented transfer of control operation data from a secondary storage device to the local memory within a control system.

Figure A.1 – Program example

The domain download has a source and a target location which are identified when the download is initiated. Each time a segment of the domain is successfully transferred the Client is notified and informed of the amount of data that has been downloaded. The Client is also notified when the download is finished. The percentage of the total data received is reported periodically while the download continues. If the download fails, the cause of the failure is reported. At the completion of the download, the performance information is kept at the Server.

The Client uses the “DomainDownload” Program to manage and monitor the download of a domain at the Server.

The basic state model for the DomainDownload Program is presented in Figure A.2. The Program has three primary states, Ready, Running, and Halted which are aligned with the standard states of a ProgramStateMachineType. Additionally, the DomainDownloadType extends the ProgramStateMachineType by defining subordinate State Machines for the Program’s Running and Halted states. The subordinate states describe the download operations in greater detail and allow the Client to monitor the activity of the download at a finer resolution.

An instance (Program Invocation) of a DomainDownload Program is created by the Client each time a download is to be performed. The instance exists until explicitly removed by the Client. The initial state of the Program is Ready and the terminal state is Halted. The DomainDownload can be temporarily suspended and then resumed or aborted. Once halted, the program may not be restarted.

Figure A.2 – DomainDownload state diagram

The sequence of state transitions is illustrated in Figure A.2. Once the download is started, The Program progresses to the Opening state. After the source of the data is opened, a sequence of transfers occurs in the Sending state. When the transfer completes the Objects are closed in the Closing state. If the transfer is terminated before all of the data is downloaded or an error is encountered then the download is halted and the Program transitions to the Aborted state; otherwise the Program halts in the Completed state. The states are presented in Table A.1 along with the state transitions.

The valid state transitions specified for the DomainDownload Program are specified in Table A.1. Each of the transitions defines a start state and end state for the transition and is identified by a unique number. Five of the transitions are from the base ProgramStateMachineType and retain the transition identifier numbers specified for Programs. The additional transitions relate the base Program states with the subordinate states defined for the DomainDownload. These states have been assigned unique transition identifier numbers that distinguish them from the base Program transition identifiers. In cases where transitions occur between substates and the Program’s base states, two transitions are specified. One transition identifies the base state change and a second substate change. For example, ReadyToRunning and ToOpening occur at the same time.

Table A.1 also specifies the defined states, causes for the transitions, and the effects of each transition. Program Control Methods are used by the Client to “run” the DomainDownload. The Methods cause or trigger the specified transitions. The transition effects are the specified EventTypes which notify the Client of Program activity.

Table A.1 – DomainDownload states

No.	Transition name	Cause	From State	To State	Effect
2	ReadyToRunning	Start Method	Ready	Running	Report Transition 2 Event/Result
3	RunningToHalted	Halt Method/Error or Internal.	Running	Halted	Report Transition 3 Event/Result
5	RunningToSuspended	Suspend Method	Running	Suspended	Report Transition 5 Event/Result
6	SuspendedToRunning	Resume Method	Suspended	Running	Report Transition 6 Event/Result
7	SuspendedToHalted	Halt Method	Suspended	Halted	Report Transition 7 Event/Result
10	OpeningToSending	Internal	Opening	Sending	Report Transition 10 Event/Result
11	SendingToSending	Internal	Sending	Sending	Report Transition 11 Event/Result
12	SendingToClosing	Internal	Sending	Closing	Report Transition 12 Event/Result
13	SendingToAborted	Halt Method/Error	Opening	Aborted	Report Transition 13 Event/Result
14	ClosingToCompleted	Internal	Closing	Completed	Report Transition 14 Event/Result
15	SendingToSuspended	Suspend Method	Sending	Suspended	Report Transition 16 Event/Result
16	SuspendedToSending	Resume Method	Suspended	Sending	Report Transition 17 Event/Result
18	SuspendedToAborted	Halt Method	Suspended	Aborted	Report Transition 18 Event/Result
17	ToOpening	Internal	Ready	Opening	Report Transition 19 Event/Result

Four standard Program Methods are specified for running the DomainDownload Program, Start, Suspend, Resume, and Halt. No additional Methods are specified. The base behaviours of these Methods are defined by the ProgramStateMachineType. The Start Method initiates the download activity and passes the source and destination locations for the transfer. The Suspend Method is used to pause the activity temporarily. The Resume Method reinitiates the download, when paused. The Halt Method aborts the download. Each of the Methods causes a Program state transition and a substate transition. The specific state transition depends on the current state at the time the Method is called. If a Method Call is made when the DomainDownload is in a state for which that Method has no associated transition, the Method returns an error status indicating invalid state for the Method.

The Start Method specifies three input arguments to be passed when it is called: Domain Name, DomainSource, and DomainDestination. The other Methods require no input arguments. No output arguments are specified for the DomainDownload Methods. The resultant error status for the Program is part of the Call Service.

A ProgramTransitionEventType is specified for each of the DomainDownload Program transitions. The EventTypes trigger a specific Event notification to the Client when the associated state transition occurs in the running Program Instance. The Event notification identifies the transition. The SendingToSending state transition also includes intermediate result data.

The SendingToSending Program transition Event relays intermediate result data to the Client along with the notification. Each time the transition occurs, data items describing the amount and percentage of data transferred are sent to the Client.

The DomainDownload Program retains final result data following a completed or aborted download. The data includes the total transaction time and the size of the domain. In the event of an aborted download, the reason for the termination is retained.

The UA model for the DomainDownload Program is presented in Clause A.2.6.2. Collectively they define the components that constitute this Program. For clarity, the figures present a progression of portions of the model that complement the contents of the tables and illustrate the Program’s composition.

The type definition for the DomainDownload Program precisely represents the behaviour of the Program in terms of UA components. These components can be browsed by a Client to interpret or validate the actions of the Program.

The DomainDownloadType is a subtype derived from the ProgramStateMachineType. It specifies the use or non-use of optional ProgramStateMachineType components, valid extensions such as subordinate State Machines, and constrained attribute values applied to instances of DomainDownload Programs.

Table A.2 specifies the optional and extended components defined by the DomainDownload Type. Note the references to two sub State Machine Types, TransferStateMachine and FinishStateMachine. The DomainDownloadType omits references to the Reset Program Control Method and its associated state transition (HaltedToReady), which it does not support.

Table A.2 – DomainDownloadType

Attribute	Value
	Includes all non-optional attributes specified for the ProgramStateMachineType
BrowseName	DomainDownloadType
IsAbstract	False
References	NodeClass	BrowseName	DataType	TypeDefinition	ModellingRule
HasComponent	Object	TransferStateMachine		StateMachineType	Mandatory
HasComponent	Object	FinishStateMachine		StateMachineType	Mandatory
HasComponent	Variable	ProgramDiagnostic		ProgramDiagnostic2Type	Mandatory
HasComponent	Object	ReadyToRunning		TransitionType
HasComponent	Object	RunningToHalted		TransitionType
HasComponent	Object	RunningToSuspended		TransitionType
HasComponent	Object	SuspendedToRunning		TransitionType
HasComponent	Object	SuspendedToHalted		TransitionType
HasComponent	Method	Start			Mandatory
HasComponent	Method	Suspend			Mandatory
HasComponent	Method	Halt			Mandatory
HasComponent	Method	Resume			Mandatory
HasComponent	Object	FinalResultData		BaseObjectType	Mandatory

Table A.3 specifies the Transfer State Machine type that is a sub State Machine of the DomainDownload Program Type. This definition identifies the StateTypes that compose the substates for the Program’s Running StateType.

Table A.3 – TransferStateMachineType

Attribute	Value
	Includes all attributes specified for the FiniteStateMachineType
BrowseName	TransferStateMachineType
IsAbstract	False
References	NodeClass	BrowseName	DataType	TypeDefinition	ModellingRule
HasComponent	Object	Opening		StateType
HasComponent	Object	Sending		StateType
HasComponent	Object	Closing		StateType
HasComponent	Object	ReadyToOpening		TransitionType
HasComponent	Object	OpeningToSending		TransitionType
HasComponent	Object	SendingToClosing		TransitionType
HasComponent	Object	SendingToAborted		TransitionType
HasComponent	Object	SendingToSuspended		TransitionType
HasComponent	Object	SuspendedToSending		TransitionType
HasComponent	Method	Start			Mandatory
HasComponent	Method	Suspend			Mandatory
HasComponent	Method	Halt			Mandatory
HasComponent	Method	Resume			Mandatory

Table A.3 specifies the StateTypes associated with the Transfer State Machine Type. All of these states are substates of the Running state of the base ProgramStateMachineType.

The Opening state is the preparation state for the domain download.

The Sending state is the activity state for the transfer in which the data is moved from the source to destination.

The Closing state is the cleanup phase of the download.

The component Variables of the TransferStateMachineType have additional Attributes defined in Table A.4.

Table A.4 – TransferStateMachineType Attribute values for child Nodes

Source Path	Value Attribute	Description Attribute
Statenumbers
Opening StateNumber	1
Sending StateNumber	2
Closing StateNumber	3
Transitionnumbers
ReadyToOpening TransitionNumber	1
OpeningToSending TransitionNumber	2
SendingToClosing TransitionNumber	3
SendingToAborted TransitionNumber	4
SendingToSuspended TransitionNumber	5
SuspendedToSending TransitionNumber	6

Table A.5 specifies the Finish State Machine Type that is a sub State Machine of the DomainDownload ProgramStateMachineType. This definition identifies the StateTypes that compose the substate for the Program’s Halted StateType.

Table A.5 – Finish State Machine Type

Attribute	Value
	Includes all attributes specified for the FiniteStateMachineType
BrowseName	FinishStateMachineType
IsAbstract	False
References	NodeClass	BrowseName	Data Type	TypeDefinition	Modelling Rule
HasComponent	Object	Completed		StateType
HasComponent	Object	Aborted		StateType

The Aborted state is the terminal state that indicates an incomplete or failed domain download operation.

The Completed state is the terminal state that indicates a successful domain download.

The component Variables of the FinishStateMachineType have additional Attributes defined in Table A.6.

Table A.6 – FinishStateMachineType Attribute values for child Nodes

Source Path	Value Attribute	Description Attribute
Statenumbers
Aborted StateNumber	8
Completed StateNumber	9

Table A.7 specifies the constraining behaviour of a DomainDownload.

Table A.7 – DomainDownloadType Property Attributes variable values

NodeClass	BrowseName	Data Type	Data Value	Modelling Rule
Variable	Creatable	Boolean	True
Variable	Deletable	Boolean	True	Mandatory
Variable	AutoDelete	Boolean	False	Mandatory
Variable	RecycleCount	Int32	0	Mandatory
Variable	InstanceCount	UInt32	PropertyType
Variable	MaxInstanceCount	UInt32	500
Variable	MaxRecycleCount	UInt32	0

A DomainDownload Program Invocation can be created and also destroyed by a Client. The Program Invocation will not delete itself when halted, but will persist until explicitly removed by the Client. A DomainDownload Program Invocation cannot be reset to restart. The Server will support up to 500 concurrent DomainDownload Program Invocations.

Figure A.3 presents a partial DomainDownloadType model that illustrates the association between the states and the DomainDownload, Transfer, and Finish State Machines. Note that the current state number for the sub State Machines is only valid when the DomainDownload active base state references the sub State Machine, Running for the Transfer current state and Halted for the Finish current state.

Figure A.3 – DomainDownloadType partial state model

Table A.8 specifies the ProgramTransitionTypes that are defined in addition to the ProgramTransitionTypes specified for Programs in Table 7. These types associate the Transfer and Finish sub State Machine states with the states of the base Program.

Table A.8 – TransferStateMachineType Additional References

Source Path	Reference Type	Is Forward	Target Path
ToSending	ToState	True	Sending
	FromState	True	Opening
	HasCause	True	Start
	HasEffect	True	ProgramTransitionEventType
	HasEffect	True	AuditProgramTransitionEventType
SendingToSending	ToState	True	Sending
	FromState	True	Sending
	HasEffect	True	ProgramTransitionEventType
SendingToClosing	ToState	True	Closing
	FromState	True	Sending
	HasEffect	True	ProgramTransitionEventType
SendingToAborted	ToState	True	Aborted
	FromState	True	Sending
	HasCause	True	Halt
	HasEffect	True	ProgramTransitionEventType
	HasEffect	True	AuditProgramTransitionEventType
ClosingToCompleted	ToState	True	Completed
	FromState	True	Closing
	HasEffect	True	ProgramTransitionEventType
SendingToSuspended	ToState	True	Suspended
	FromState	True	Sending
	HasCause	True	Suspend
	HasEffect	True	ProgramTransitionEventType
	HasEffect	True	AuditProgramTransitionEventType
SuspendedToSending	ToState	True	Sending
	FromState	True	Suspended
	HasCause	True	Resume
	HasEffect	True	ProgramTransitionEventType
	HasEffect	True	AuditProgramTransitionEventType
SuspendedToAborted	ToState	True	Aborted
	FromState	True	Suspended
	HasCause	True	Halt
	HasEffect	True	ProgramTransitionEventType
	HasEffect	True	AuditProgramTransitionEventType
ReadyToOpening	ToState	True	Opening
	FromState	True	Ready
	HasCause	True	Start
	HasEffect	True	ProgramTransitionEventType
	HasEffect	True	AuditProgramTransitionEventType

Figure A.4 through Figure A.10 illustrate portions of the DomainDownloadType model. In each figure, the referenced tates, Methods, transitions, and EventTypes are identified for one or two state transitions.

Figure A.4 – Ready To Running model

Figure A.4 illustrates the model for the ReadyToRunning Program transition. The transition is caused by the Start Method. The Start Method requires three input arguments. The Method Call service is used by the Client to invoke the Start Method and pass the arguments. When successful, the Program Invocation enters the Running state and the subordinate Transfer Opening state. The Server issues two Event notifications, ReadyToRunning (2), and ToOpening (19).

Table A.9 – Start Method additions

Attribute		Value
BrowseName		Start
IsAbstract		False
References	NodeClass	BrowseName	DataType	TypeDefinition	ModellingRule
HasProperty	Variable	InputArguments	Argument[]	PropertyType

Table A.9 specifies that the Start Method for the DomainDownloadType requires input arguments. Table A.10 identifies the Start Arguments required.

Table A.10 – StartArguments

Name	Type	Value
Argument 1	structure
name	String	SourcePath
dataType	NodeId	StringNodeId
valueRank	Int32	-1 (-1 = scalar)
arrayDimensions	UInt32[]	null
description	LocalizedText	The source specifier for the domain
Argument 2	structure
Name	String	DestinationPath
dataType	NodeId	StringNodeId
valueRank	Int32	-1 (-1 = scalar)
arrayDimensions	UInt32[]	null
description	LocalizedText	The destination specifier for the domain
Argument 3	structure
name	String	DomainName
dataType	NodeId	StringNodeId
arrayDimensions	UInt32[]	null
valueRank	Int32	-1 (-1 = scalar)
description	LocalizedText	The name of the domain

Figure A.5 illustrates the model for the Opening To Sending and the Sending to Closing Program transitions. As specified in the transition table, these state transitions require no Methods to occur, but rather are driven by the internal actions of the Server. Events are generated for each state transition (10 to 12), when they occur.

Figure A.5 – Opening To Sending To Closing model

Notice that a state transition can initiate and terminate at the same state (Sending). In this case the transition serves a purpose. The ProgramTransitionEventType effect referenced by the SendingToSending state transition has an IntermediateResultData Object Reference. The IntermediateResultData Object serves to identify two Variables whose values are obtained each time the state transition occurs. The values are sent to the Client with the Event notification. Table A.11 defines the IntermediateResults ObjectType and Table A.12 defines the Variables of the ObjectType.

Table A.11 – IntermediateResults Object

Attribute	Value
	Includes all attributes specified for the ObjectType
BrowseName	IntermediateResults
IsAbstract	False
References	NodeClass	BrowseName	Data Type	TypeDefinition	Modelling Rule
HasComponent	Variable	AmountTransferred	Long	VariableType	Mandatory
HasComponent	Variable	PercentageTransferred	Long	VariableType	Mandatory

Table A.12 – Intermediate result data Variables

Intermediate Result Variables	Type	Value
Variable 1	Structure
Name	String	AmountTransferred
dataType	NodeId	StringNodeId
description	LocalizedText	Bytes of domain data transferred.
Variable 2	Structure
Name	String	PercentageTransferred
dataType	NodeId	StringNodeId
description	LocalizedText	Percentage of domain data transferred.

The model for the Running To Suspended state transition is illustrated in Figure A.6. The cause for this transition is the Suspend Method. The Client can pause the download of domain data to the control. The transition from Running to Suspended invokes the Event generation for TransitionEventTypes 5 and 16. Note that there is no longer a valid current state for the Transfer State Machine.

Figure A.6 – Running To Suspended model

The model for the SuspendedToRunning state transition is illustrated in Figure A.7. The cause for this transition is the Resume Method. The Client can resume the download of domain data to the control. The transition from Suspended to Running generates the Event for TransitionEventTypes 6 and 17. Now that the Running state is active, the Sending state of the Transfer State Machine is again specified for the CurrentStateNumber.

Figure A.7 – Suspended To Running model

The model for the Running To Halted state transition for an abnormal termination of the domain download is illustrated in Figure A.8. The cause for this transition is the Halt Method. The Client can terminate the download of domain data to the control. The transition from Running To Halted generates the Event for TransitionEventTypes 3 and 15. The TransitionEventType 15 indicates the transition from the Sending state as the Running State ends and then to the Aborted state as the Halted state is entered.

Figure A.8 – Running To Halted – Aborted model

Figure A.9 illustrates the model for the Suspended To Halted state transition for an abnormal termination of the domain download. The cause for this transition is the Halt Method. The Client can terminate the download of domain data to the control while it is suspended. The transition from SuspendedToHalted invokes the Event notifiers for TransitionEventTypes 7 and 18.

Figure A.9 – Suspended To Aborted model

The model for the Running To Completed state transition for a normal termination of the domain download is illustrated in Figure A.10. The cause for this transition is internal. The transition from Closing To Halted generates the Event for TransitionEventTypes 3 and 14. The TransitionEventType 14 indicates the transition from the Closing state as the Running state ends and then to the Completed state as the Halted state is entered.

The DomainDownloadType includes a component reference to a FinalResultData Object. This Object references Variables that persists information about the domain download once it has completed. This data can be read by Clients who are not subscribed to Event notifications. The result data is described in Table A.13.

Table A.13 – FinalResultData

Attribute	Value
	Includes all attributes specified for the ObjectType
BrowseName	FinalResultData
IsAbstract	False
References	NodeClass	BrowseName	Data Type	TypeDefinition	Modelling Rule
HasComponent	Variable	DownloadPerformance	Double	BaseDataVariableType	Mandatory
HasComponent	Variable	FailureDetails	String	BaseDataVariableType	Mandatory

The Domain Download net transfer data rate and detailed reason for aborted downloads is retained as final result data for each Program Invocation.

DownloadPerformance provides the data rate in seconds for domain data transferred.

FailureDetails provides a descriptive reason for an abort.

Figure A.10 – Running To Completed model

Figure A.11 illustrates a normal sequence of service exchanges between a Client and Server that would occur during the life cycle of a DomainDownloadType Program Invocation.

Figure A.11 – Sequence of operations

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