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| SSD19 - Simulating Timing Behavior |
LSE19 - Zeitverhalten simulieren
1 Allocation to V-Model and Methods Allocation
V-Model
SD2.3 - Investigation of Feasibility
SD5.2 - Analysis of Resources and Time Requirements
Method
2 Brief Characteristics
This service unit defines the requirements for tools used to simulate processes on a computer system that cannot be actually realized based on time, cost, and other reasons. This not only includes the simulation of airplane control but also the simulation of software during planning phases the way it is expressed in
- interface specifications,
- process models and
- logical schema specifications of databases.
The simulation of software requires that actual data are available about:
- how many calculations have to be realized for an action (1),
- how many memory accesses are required,
- what data volumes have to be moved between main memory and processor,
- how many accesses are required to disk drives,
- what data volumes have to be moved between hard disk and main memory.
The following must be known with regard to the simulated computer system:
- the processor performance (clocks per statement, statements per second),
- the transmission rate between processor and main memory,
- the transmission rate between computer and disk storage.
When simulating real-time software systems it is also required to take into consideration the peripheral devices and their corresponding reaction times as well as the input and reaction time for user input.
3 Requirements
3.1 Requirements for Interfaces
| SSD19.I.1 | Granularity | The exchange of control parameters with SWFM01 - Workflow Management is possible for individual closed function packages of the tool by means of a disclosed, documented interface. |
| SSD19.I.2 | Input interface to SSD02 - Supporting Specification of User Interfaces | It is possible to integrate interface specifications generated with SSD02 without further transformation directly from the object management in order to simulate the time behavior. |
| SSD19.I.3 | Input interface to SSD04 - Supporting Process Modeling | It is possible to integrate process models generated with SSD04 without further transformation directly from the object management in order to simulate the time behavior. |
| SSD19.I.4 | Input interface to SSD11 - Supporting Database Specification | It is possible to integrate logical schema specifications for databases and data structures generated with SSD11 without further transformation directly from the object management in order to simulate the time behavior. |
3.2 Requirements for the Methods Support
| SSD19.M.1 | SIMU - Simulation Models | |
| SSD19.M.1.1 | Resources | |
| SSD19.M.1.1.1 | Restricted availability |
It is possible to restrict the availability of resources. Resources are CPU, bus, memory, controller, hard disks, peripherals; in a multitasking operating system, an individual program can only have parts of the total capacity at disposal. |
| SSD19.M.1.1.2 | Exclusive availability | It is possible to make resources available exclusively to a single process. |
| SSD19.M.1.1.3 | Simultaneous utilization | It is possible to make resources available to different processes for simultaneous use. |
| SSD19.M.1.1.4 | Utilization rules |
It is possible to regulate the utilization of resources by a special procedure. There are rules for the access to a computer bus. |
| SSD19.M.1.1.5 | Mapping | Without restrictions, it is possible to map resources. |
| SSD19.M.1.1.6 | Availability limitations | It is possible to model all availability limitations. |
| SSD19.M.1.2 | Waiting queues | |
| SSD19.M.1.2.1 | Mapping | It is possible to map waiting queues. |
| SSD19.M.1.2.2 | Limitations |
It is possible to limit the capacity of waiting queues. The instruction code storage of a computer can be limited. |
| SSD19.M.1.2.3 | Priority rules | It is possible to specify priority rules for waiting queues. |
| SSD19.M.1.2.4 | Changing the priority | It is possible that the priorities in a waiting queue will change during the time or because of external influences. |
| SSD19.M.1.2.5 | Status request | It is possible to request the status of a waiting queue at any time. |
| SSD19.M.1.3 | Activities | |
| SSD19.M.1.3.1 | Preset time | It is possible to preset the time demand for an activity. |
| SSD19.M.1.3.2 | Calculation of preset time | It is possible to calculate the time demand for an activity with arbitrary formulas. |
| SSD19.M.1.3.3 | Time demand depending on activities | It is possible that the time demand of an activity depend on its characteristics. |
| SSD19.M.1.3.4 | External influences | It is possible that the time demand of an activity is determined by external influences. |
| SSD19.M.1.3.5 | Stochastic distribution | It is possible that the time demand to execute an activity is stochastically distributed. |
| SSD19.M.1.3.6 | Optional combinations | It is possible to optionally combine the above listed influence factors for activities. |
| SSD19.M.1.4 | Logical operations | |
| SSD19.M.1.4.1 | AND/OR | It is possible to specify at least the logical operations "AND" and "OR". |
| SSD19.M.1.4.2 | Impact on resources | It is possible that logical operations reduce the availability of resources. |
| SSD19.M.1.4.3 | Impact on processing sequence | It is possible that logical operations determine the processing sequence. |
| SSD19.M.1.5 | Events | |
| SSD19.M.1.5.1 | External interventions |
It is possible to simulate external interventions by means of events. External interventions are user input, hardware interrupts, software interrupts. |
| SSD19.M.1.5.2 | Changing the system state |
It is possible that events change system states. Global and also continuous variables may change. |
| SSD19.M.1.5.3 | Impact on availability of resources |
It is possible that events have an impact on the availability of resources. The failure of system parts can thus be simulated. |
| SSD19.M.1.5.4 | Initialization of processes | It is possible that events initialize processes. |
| SSD19.M.1.5.5 | Initialization by a process |
It is possible that events are initialized by processes. A process may cause a switching operation. |
| SSD19.M.1.5.6 | Initialization by status changes |
It is possible that events are initialized by status changes. When crossing a threshold value of a continuous status item, an event might be initialized. |
| SSD19.M.1.6 | Status changes | |
| SSD19.M.1.6.1 | Continuous | It is possible that system states change continuously. |
| SSD19.M.1.6.2 | Linear equations | It is possible to describe status changes by linear equations. |
| SSD19.M.1.6.3 | Differential equations | It is possible to describe status changes by differential equations. |
| SSD19.M.1.6.4 | Supply with solution procedures | Solution procedures for equations are made available. |
| SSD19.M.1.6.5 | Impact of events | It is possible to influence system states by events. |
| SSD19.M.1.6.6 | Impact of global variables |
It is possible to influence system states by global variables. Loading factors of resources may have an impact on the system behavior. |
| SSD19.M.1.6.7 | Impact of local variables |
It is possible to influence system states by local variables. Local variables are attributes of processes. |
| SSD19.M.1.6.8 | Impact on activity duration | It is possible that a duration of activities is influenced by system states. |
| SSD19.M.1.6.9 | Independent development |
It is possible that system states develop independently of the modeled interconnections. Thus it is possible to describe external influences with regard to measuring and control technology systems. |
| SSD19.M.1.7 | Interrupts | |
| SSD19.M.1.7.1 | Interrupt at any time | The simulation is interruptible at any time. |
| SSD19.M.1.7.2 | Manual | It is possible to cause interrupts manually. |
| SSD19.M.1.7.3 | Predefined | It is possible to predefine interrupts. |
| SSD19.M.1.7.4 | Time-oriented | It is possible that interrupts are oriented on the simulation time. |
| SSD19.M.1.7.5 | Status-oriented | It is possible that interrupts are oriented on system states. |
| SSD19.M.1.7.6 | Event-oriented |
It is possible that interrupts are linked with events. The simulation can be interrupted after a certain event has occurred. |
| SSD19.M.1.7.7 | Status representation |
During an interrupt, it is possible to represent all states. Variables can be queried. |
| SSD19.M.1.7.8 | Status changes |
It is possible to change system states manually. Variables or parameters can be changed. |
| SSD19.M.1.7.9 | Sequence changes |
It is possible to intervene in the simulation process. Processes can be interrupted or re-initialized. |
| SSD19.M.1.7.10 | Step-by-step continuation | It is possible to continue the simulation on a step-by-step basis after an interruption. |
| SSD19.M.1.7.11 | Unlimited continuation | Without restrictions it is possible to continue the simulation after an interruption. |
| SSD19.M.1.8 | Status backup | |
| SSD19.M.1.8.1 | Storing | It is possible to store simulation states. |
| SSD19.M.1.8.2 | Reloading | It is possible to reload simulation states. |
| SSD19.M.1.9 | Logging | It is possible to generate a sequence list containing all processes, activities and events happened. |
3.3 Requirements for Functions
| SSD19.F.1 | Animation | It is possible to visualize the simulation by an animation. |
3.4 Other Requirements
| SSD19.O.1 | Macro language | It is possible to control the simulation process by means of a macro language. |
| SSD19.O.2 | Upward compatibility | It must be possible to process objects generated with an older release of the tool with the later release of that tool, without loss of information and functionality. |
| SSD19.O.3 | Procedural command language | The tool has a procedural command language that can be applied by the user to generate and run macros or procedures. |
| SSD19.O.4 | Complexity | There is no limitation of the complexity caused by the tool itself. |
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GDPA Online
Last Updated 01.Jan.2002
Updated by Webmaster
Last Revised 01.Jan.2002
Revised by Webmaster
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