Logic Simulator System

Use case diagram:

Flow of events:

Select Vendor:

Pre-condition: User has provided the name of a flowsheet to use

Basic Path:

1. User requests to select a vendor for choosing components
2. A list of vendors is presented to the user
3. User selects a vendor from the list
4. Selected vendor is remembered as the default vendor by the system

Alternate Path:

• There is always a default vendor that the system uses, even if the user has never selected one

Post-condition: System knows the default vendor to use for components.

Select Component:

Pre-condition: User has provided the name of a flowsheet to use

Basic Path:

1. User requests to select a component
2. System presents list of all components like AND, OR, etc. The list displayed only shows components provided by the default vendor selected by the user
3. User selects a component
4. System asks for a name for the component
5. User provides name for component
6. System verifies the name is unique
7. System creates an instance of the component and adds to a collection of components

Alternate Path:

• If in step 6 the component name is not unique, ask user to enter a unique name

Post-condition:

Connect Components:

Pre-condition: User has provided the name of a flowsheet to use

Basic Path:

1. User provides the name of the first component to connect from
2. User provides the name of the second component to connect to
3. User provides the second component’s input number to connect to
4. System establishes the connectivity

Alternate Path:

• In step 1 or 2 if given component name is not valid, ask user to reenter
• In step 3, if given input number is not valid, as user to reenter

Post-condition: A connectivity has been established

Save Flowsheet:

Pre-condition: User has provided the name of a flowsheet to use

Basic Path:

1. User requests the flowsheet to be saved
2. System stores the flowsheet under the given name at given location

Alternate Path:

• If error saving the flowsheet, inform user

Post-condition: Flowsheet is saved

Remove Component:

Pre-condition: User has provided the name of a flowsheet to use

Basic Path:

1. User provides the name of the component to remove
2. System removes the component from the collection
3. Any connectivity for that component is also removed

Alternate Path:

• In step 1 if given component name is not valid, ask user to reenter

Post-condition: Given component removed from system

List Components and Connectivity:

Pre-condition: User has provided the name of a flowsheet to use

Basic Path:

1. User wants to list the components and connectivity
2. System displays the names and types of the components and any connectivity information for each component.

Alternate Path:

Post-condition: -

Run Flowsheet:

Pre-condition: User has provided the name of a flowsheet and an input file to use

Basic Path:

1. System first reads and sets the input values for each component specified in the input file.
2. It then loops through the components in the collection evaluation their state
3. For each component with unconnected output, it displays the value of output
4. This repeats at one second interval, until the user asks to terminate

Alternate Path:

• If any of the component names or input numbers specified in the input file are invalid, system reports this and terminates

Post-condition: -