Informatische Bildung - Neue Einsichten für Neugierige/Zusatzmaterial/Workflow

The definitions given here apply to →artefacts whose purpose is

• to do something (activity, here called production steps)
• to something (object, here called products)
• by means of something (instrument).

Conforming to the →Chinese Box principle, activities can be composed of sub-activities, which can be considered at a lower level. The same holds for products, instruments, production steps, recipes, etc.

Note that we avoid th term "process", as it has too many different meanings in the literature.

Worum geht es?

• Die Fabrik muss auf Bestellung Objekte liefern.
• Eine Bestellung bestellt gewisse Objekte zu gewissen Liefermomenten.
• Zu jedem lieferbaren Objekt gehört mindestens ein Rezept.
• Um ein Objekt zu einem gegebenen Moment zu liefern, muss ein Vorgang ablaufen, in dem eine Charge alle durch ein Rezept definierten Schritte durchläuft.
• Zu jedem dieser Schritte sind laut Rezept gewisse Instrumente nötig. (Scheduling!)
• In einer Fabrik gehört oft zu einem Instrument ein Dienst, der dieses Instrument immer wieder gebraucht für Schritte für jedesmal andere Chargen.

Basic concepts

concept	definition	world	special cases	examples					remark
				Auto	Wikipedia	Öl-Raffinerie	information system	Restaurant
product (Objekt)	Substances, information, people, or money that are objects of processing	reality	ingredient, raw product, half product, end product, catalysator	Bremsscheibe, Bremsflüssigkeit	Buchstabe, geschriebenes Wort, Bild	Öl, Luft, Energie	Vorgang	Gurke, Fisch, Salz
instrument Instrument, Werkzeug	A →thing that is used for production	reality	plant, vehicle, resource	Warnlampe, Bremspedal	Bildschirm, Tastatur, Maus	Rohr, Kompressor, Tank	a subroutine together with its memory allocation and processor	Küchenwerkzeug: Messer, Herd, Schüssel	An instrument can only be used once at any moment. One production step can require several instruments. The same intrument can be necessary for different production steps, in which case conflicts have to be resolved.
production step Produktionsschritt	a procedure that takes some products as ingredients (precondition), performs some operation, thereby using some instrments for a certain time, and produces some products (postcondition)	reality	thread?	Bremskraft wird verstärkt	Eine Auswahl der Suchergebnisse wird angezeigt	Destillation, Reinigung, Öltransport durch die Pipeline		Salat wird zubereitet, Fisch wird gebraten,	the crossing point of a service and a batch
batch Charge	a quantity of products moving from production step to production step resulting in one end product	reality		Bremsflüssigkeit, Bremsklotz, Bremsscheibe	Internetverbindung, Computer, Tastatur, server der Wikipediaseite	Leichtöl, Heizöl		Gesamtheit aller Zutaten des Rezepts	orthogonal to service
service Dienst	the iterative execution of a production step with the same instrument for different batches	reality	actor, task	Spezifiaktion der Funktionsweise des Bremsflüssigkeitssensors	Abfrage der Tastatur	Schließen eines Ventils, Erhitzen		Salat putzen, Fisch säubern	orthogonal to batch
scenario Vorgang	all production steps that actually happen in a period of time	reality		Bremsen	Informationen zum Stichwort "Goch" finden	Benzinherstellung		Fisch essen in einem Restaurant	Within a scenario, many batches and services can be identified.
recipe (Vorgangsbeschreibung)	The specification of a class of batches that result in a certain product	description		mit dem rechten Fuß das Bremspedal betätigen, Kupplung betätigen, Gang auskuppeln, ..	Internetseite aufrufen, Stichwort ein geben, Enter-Taste betätigen…	Beschreibung der Funktionsweise der Fabrik		Fisch provencalisch, Tagesmenue	A recipe for a product. Recipes usually specify partial orders of production steps, where the products of steps are ingredients for other steps.
functionality (Dienstbeschreibung)	The specification of a service	description		Sensor registriert Niveau der Bremsflüssigkeit	Bei Betätigung einer bestimmten Taste ein spezifisches Signal weiterleiten	Reinigungsverfahren, Bedingungen für das Schließen des Ventils		Tomaten in Scheiben schneiden, Fisch scharf anbraten,..	the functionality of a service
order Bestellung	A bag of pairs (product, due date)	description		Betätigung des Bremspedals	Abschicken der Suchanfrage durch Betätigung der ENTER-Taste	Lieferauftrag von Firma x		Bestellung des Tagesmenues durch die Dame an Tisch 2	A scenario conforms to an order if it contains a production step that produces the ordered product at the ordered moment.

The story

• Design and verification of an artefact for production
  • The purpose of many artefacts is the production of products of a certain class.
  • The design of such an artefact is based on recipes for the intended products.
  • The artefact must provide services for all production steps required by all recipes involved.
• Design of a control
  • Get the recipes for all ordered products
  • Determine a schedule, i.e. a class of scenarios that contain the batches that conform to these recipes and orders and that can be produced by the available services without conflicts
  • Control the services conforming to this schedule.
• Verification of a control
  • For any order, there is a batch that conforms to that order.
  • For all steps in all such batches there is a service that can perform it.
• Efficiency
  • All steps should conform to an order.
  • All products should either be ordered or be input for steps that conform to some order.
  • Services should not be idle.

Relations

• a recipe for a product, ingredients for a recipe
• ingredient for a step, result of a step, resource for a step
• a plant suitable for a recipe, i.e. a plant for which a schedule for an order of the result of that recipe exists
• ...

Problems

Modelling problems

reverse engineering 

model a given physical plant so that the model can be used for the verification of a controller. This involves the identification of intruments that match production steps from the intended recipes.

Design problems

production line 

Given a recipe, design a plant that repetitively produces products conforming this recipe as quickly as possible

processor 

Given a generic recipe, design a plant that fulfils orders for instances of this recipe when they come in as soon as possible. (Example: printer)

multi-purpose plant 

Given a (usually small) set of recipes, design a plant that takes orders for results of these recipes and fulfills them conforming to some efficiency measure

universal plant 

Design a kitchen that takes orders together with recipes and fulfills them

Decision problems

• Is a plant suitable for a recipe?
• Is a plant suitable for an order? Viz. is there a schedule for a given plant and a given order?
• What can be done with the waste? Not all output of certain steps of a recipe is used as input for subsequent steps in the same recipe. Can different recipes be so combined that waste is minimal?