Chapter 9

Question 1

Architectural Patterns vs. Design Patterns

Answer 1

Architectural patterns focus on the concept while Design patterns focus on the implementation

Question 1

5 Architectural Patterns

Answer 1

1. Model-View-Controller
2. Layered
3. Repository
4. Client-Server
5. Pipe and Filter

Question 2

MVC Uses

Answer 2

Used when the are multiple ways to view and interact with data, or when future requirements for interaction and presentation are unknown.

Question 3

Pro of MVC

Answer 3

Allows data to change independently of its representation and vice versa. Changes in one view shown in all of them

Question 4

Con of MVC

Answer 4

Additional code and code complexity

Question 5

Pros of Layered Pattern

Answer 5

Allows replacement of an entire layer as long as the interfaces maintain
Increased dependability possible since redundant facilities can be provided in each layer

Question 6

Cons of Layered Pattern

Answer 6

In practice, clean separation of layers is difficult
Direction communication across layers not immediately adjacent might be required
Performance overhead due to multiple levels of interpretation of a service request

Question 7

Use for Repository Pattern

Answer 7

Used when large volumes of data are generated and have to be stored for a long time. Also used in data-driven systems where the inclusion of data in the repository/database triggers an action, event, or tool

Question 8

Uses of Layered Pattern

Answer 8

Used when development is spread across several teams with each responsible for a layer of functionality
When a multi-level security is required.

Question 9

Pros of Repository Pattern

Answer 9

Components can be independent and do not need to know of the existence of other components
Changes made by one component to the data can be propagated to all components
All data can be managed consistently as it is all centralized in one place.

Question 10

Cons of Repository Pattern

Answer 10

The repository is a single point of failure, and distributing the repository/database across several nodes may be difficult
Inefficiencies in the components’ communications
Components must operate around an agreed repository/database data model

Question 11

Purpose of Client-Server Pattern

Answer 11

Shows the dynamic view of distributed systems. It organizes a system as a set of services and associated servers and clients

Question 12

Pros of Client-Server Pattern

Answer 12

Servers can be distributed across a network, and general functionality can be available to all clients without the need for implementation by all servers providing the services.
Servers can be upgraded transparently
Many distributed processors may be utilized efficiently

Question 13

Cons of Client-Server Pattern

Answer 13

Each service is a single point of failure susceptible to denial-of-service attacks or server failures
Unpredictable performance depending on the network conditions and various nodes
Management problems if servers owned by different organizations

Question 14

Origin of Pipe and Filter Pattern

Answer 14

Pipes comes from UNIX pipes
Filter means the transformation filters out the data it can process from the input stream

Question 15

Purpose of Pipe and Filter Pattern

Answer 15

Used in data processing applications where inputs are processed in separate stages to generate related outputs

Question 16

Pros of Pipe and Filter

Answer 16

Easy to comprehend
Supports transformation reuse
Workflow style matches the structure of many business processes
Evolution by adding transformations is straightforward
Can be implemented as either a sequential or a concurrent system

Question 17

Cons of Pipe and Filter

Answer 17

Data transfer format has to be agreed between communicating transformations
Increased system overhead
May be impossible to reuse architectural components that use incompatible data structures

Question 18

Architectural Patterns vs Reference Architectures

Answer 18

Patterns are technology and domain agnostic. Architectures are for applications in specific domains