Lecture 1B - EA as a set of models Flashcards
What is Enterprise Architecture (In a very simple definition) ?
A combination of tens of thousands artifacts (lists, tables, diagrams) that describe a business and its systems.
-Includes: Current state, future state and migration plan
What is Information Technology (IT)?
The combination of:
- Hardware
- Software
- Data
- Network
- Procedures
- People
What is a flowchart?
A diagram that represents a workflow or process. *It can also be a representation of an algorithm.
What are the most common notations in a flow chart?
- Arrow is the flowline
- Oval rectangle is a start or end point
- A block is a process
- A triangle is a decision
- An italic rectangle is an input or output
What 3 types of views do you have in a flowchart?
- Designer view (with the notations described)
- Developer view (In programming language)
- In user view (in CMD exe)
What are data models and which 2 views do you have?
-> Models about databases
User view - Expressed in a spreadsheet style
Developer view - SQL language
What is a Physical Database model?
A database model for database engineers that is dependent on the technology they use.
- It shows columns in separate table, with in the table a candidate key, a primary key and a foreign key.
- Related columns are linked by lines.
What is the Logical Database model
A database model for database designers/architects. It is technology independent and often uses the Relational Model.
- It shows which tables are present in the database.
- It shows the attributes of each tables in a row, with the primary key underlined.
- The primary keys are linked to the foreign keys in other tables with arrows.
What is the Conceptual Data(base) model?
A database model for business owners / analysts. It is Design and Technology independent and often uses the Entity-Relationship model.
- It shows Entities as separate tables with their attributes. Attributes are listed in the tables Identifiers (PK) are underlined;
- It shows relationships between the tables as well as their cardinality;
- Composite attributes have round brackets;
- Multi-values attributes have curly brackets;
- Calculated attributes have square brackets;
Which user uses the Conceptual Database model?
Business Managers / Analysts
- Entity Relationship Model
Which user uses the Logical Database model?
Database Designers / Architects
- Relational Model
Which user uses the Physical Database Model?
Database Engineers
- Technology Dependent
What are the main differences between a Conceptual Model and a Logical Model?
- Logical (Designers) only has 1-N and 1-1 relationships whereas Conceptual Model (business) has N-N relationships;
- Conceptual model may lack identifiers, because business managers might not be aware of them. Logical model needs to have PK’s.
What is the process of developing a database system?
Step 1: Make conceptual model for current state
Step 2: Make conceptual model for to be state
Step 3: Map the conceptual model into the logical model
What is UML?
Unified Modeling Language. - Several software engineering diagrams under 1 umbrella.
Focus:
- Use-case diagram
- Activity diagram
- These are used in system diagrams and business diagrams
What is a system use-case diagram?
- Diagram about what a system does.
- Providing a bird view
- Design-dependent & Technology-independent
- Shows which functionalities (use cases) are supported in a system (Registering/login/watch movie/log out)
- Shows the relationship between functionalities
When is a functionality considered a functionality?
When it has at least two steps
What are the most important symbols in a system use-case diagram?
- The actor is portayed with a circle with a smiley or with a poppetje
- Use cases are circles
- The system is a big non-filled square around the functionalities
- Relationships are arrows
What is a system activity diagram?
- A diagram about a system that shows how the system does that. It focuses on a specific functionality that is given in a system use-case diagram;
- Shows all the steps that are taken with the system to successfully complete the functionality/process;
- Often a swimlane model. The lanes are the different actors involved in the process;
- Design dependent and technoloy-independent;
What are the most important symbols in a system activity diagram?
- A square with round edges is an action;
- An arrow indicates the action flow;
- A triangle is a decision point;
What is a business use-case diagram?
- A diagram about what the business does.
- Design independent
- Gives a bird view
- Shows the functionality of a business
- Shows physical, manual and digital functionalities;
- Involves external actors, such as customers, suppliers
What is a business activity diagram?
- A diagram about how the business does it;
- Gives a detailed view of all the steps for a single business functionality
- Often a swimlane model, in which the lanes are actors (can include outside actors like customer and delivery guy)
- Same symbols as for the system activity;
How do the business and system use case and activity models relate to each other?
- Business diagrams are conceptual whereas the system diagrams are logical
- The activity diagrams of each give a detailed view of a functionality within a use-case diagram;
- The bussiness activity diagram helps developing the system activity diagram
- The business use case diagram helps developing the system use case diagram
What is the CRUD Matrix?
A matrix that helps connecting diagrams to see if the combination of them is valid.
C -> Create
R -> Read
U -> Update
D -> Delete
- You can put entities in the columns and functionalities as rows;
- Can be used to check the current state and to see per entity column if there are functionalities or processes missing
