Difference between revisions of "Entity Data Model"

Revision as of 14:37, 18 December 2012

Introduction

Objectives

In an industrial environment we quite often need to

describe an industrial plant consisting of a bunch of different parts, each having a certain purpose and set of properties, and which are related in various ways
manage process or maintenance data of the plant and its features
do a high-performance cost-benefit analysis and create key performance indicators

Therefore we need to

15 px „Dissemble“ the system into theoretical blocks representing the real as well as intangible parts of the system.
15 px Identify the necessary properties of the blocks.
15 px Think about how blocks are possibly related to each other.
15 px Think about the functions and features of blocks.

Plant picture

Lets start with a simple picture and assume that our plant consists of a pump and an armature. Both equipments exhibit certain technical or other properties, which our datamodel must contain in some form. Additionally the datamodel has to provide mechanism to indicate the circumstances that both equipments are parts of the plant and maybe even be related to each other.

For our first example plant, the pump and armature we find the following definitions

Looking closer at the "PUMP" block reveals its properties and property values

Of course, a real plant consists of multiple pumps, each described with the same set of properties (TAG, vendor, power, maintenance data). The real pumps in the plant are distinguished by different property values as given in the table.

Pump	TAG	Vendor	Power	Maintenance
#1	P0815	Andritz	2 kW	Yearly
#2	P0816	Andritz	5 kW	Monthly
#3	P0817	Sulzer	4 kW	Yearly

We can redefine or extend our objectives by

15 px Design a descriptive model including all required blocks and properties of the system
15 px An object in this model specifies possible properties for a certain part of the real system

From the plant picture to UBIK

Transition

In summary we can picture the transition from the plant picture into an object- / data-model like

and post our first definition

UBIK metamodel: A descriptive model, where objects provide information about the aspects of the data, is also called “Metamodel”.

Intermediate summary I

So far we have identified

20 px Theoretical blocks representing the parts of the system

20 px Necessary properties of these blocks

An important aspect of the datamodel has not been discussed yet, namley

20 px How are the blocks (=metaclasses) related to each other?

Relating objects

Assuming that all three pumps are clearly parts of the plant „UBIK1“, the descriptive model has to be extended in order to include this information as well. In our "table" view we account for this by adding a property to the „Pump“ block refering to the plant. This additional property represents the link information between the pumps #1 - #3 and the plant „UBIK1“.

20 px

Pump	TAG	Vendor	Power	Maintenance
#1	P0815	Andritz	2 kW	Yearly
#2	P0816	Andritz	5 kW	Monthly
#3	P0817	Sulzer	4 kW	Yearly

@@ Line 95: / Line 95: @@
 [[File:UDOM_Relating1.png|400 px]]
 [[File:ArrowGreenRight.png|20 px]]
+{| class="wikitable"
+|-
+! Pump !! TAG !! Vendor !! Power !! Maintenance
+|- align="center"
+| #1 || style="width: 80px;" | P0815 || style="width: 100px;" | Andritz || style="width: 50px;" align="right" | 2 kW || Yearly
+|- align="center"
+| #2 || P0816 || Andritz || align="right" | 5 kW || Monthly
+|- align="center"
+| #3 || P0817 || Sulzer || align="right" | 4 kW || Yearly
+|}
 [[File:UDOM_Relating2.png|400 px]]