1. Layered pattern
This pattern can be used to structure programs that can be
decomposed into groups of subtasks, each of which is at a particular level of
abstraction. Each layer provides services to the next higher layer.
The most commonly found 4 layers of a general information
system are as follows.
Presentation layer (also known as UI layer)
Application layer (also known as service layer)
Business logic layer (also known as domain layer)
Data access layer (also known as persistence layer)
Usage
General desktop applications.
E commerce web applications.
Layered pattern
2. Client-server pattern
This pattern consists of two parties; a server and multiple
clients. The server component will provide services to multiple client
components. Clients request services from the server and the server provides
relevant services to those clients. Furthermore, the server continues to listen
to client requests.
Usage
Online applications such as email, document sharing and
banking.
Client-server pattern
3. Master-slave pattern
This pattern consists of two parties; master and slaves. The
master component distributes the work among identical slave components, and
computes a final result from the results which the slaves return.
Usage
In database replication, the master database is regarded as
the authoritative source, and the slave databases are synchronized to it.
Peripherals connected to a bus in a computer system (master
and slave drives).
Master-slave pattern
4. Pipe-filter pattern
This pattern can be used to structure systems which produce
and process a stream of data. Each processing step is enclosed within a filter
component. Data to be processed is passed through pipes. These pipes can be
used for buffering or for synchronization purposes.
Usage
Compilers. The consecutive filters perform lexical analysis,
parsing, semantic analysis, and code generation.
Workflows in bioinformatics.
Pipe-filter pattern
5. Broker pattern
This pattern is used to structure distributed systems with
decoupled components. These components can interact with each other by remote
service invocations. A broker component is responsible for the coordination of
communication among components.
Servers publish their capabilities (services and
characteristics) to a broker. Clients request a service from the broker, and
the broker then redirects the client to a suitable service from its registry.
Usage
Message broker software such as Apache ActiveMQ, Apache
Kafka, RabbitMQ and JBoss Messaging.
Broker pattern
6. Peer-to-peer pattern
In this pattern, individual components are known as peers.
Peers may function both as a client, requesting services from other peers, and
as a server, providing services to other peers. A peer may act as a client or
as a server or as both, and it can change its role dynamically with time.
Usage
File-sharing networks such as Gnutella and G2)
Multimedia protocols such as P2PTV and PDTP.
Peer-to-peer pattern
7. Event-bus pattern
This pattern primarily deals with events and has 4 major
components; event source, event listener, channel and event bus. Sources
publish messages to particular channels on an event bus. Listeners subscribe to
particular channels. Listeners are notified of messages that are published to a
channel to which they have subscribed before.
Usage
Android development
Notification services
Event-bus pattern
8. Model-view-controller pattern
This pattern, also known as MVC pattern, divides an
interactive application in to 3 parts as,
model — contains the core functionality and data
view — displays the information to the user (more than one
view may be defined)
controller — handles the input from the user
This is done to separate internal representations of
information from the ways information is presented to, and accepted from, the
user. It decouples components and allows efficient code reuse.
Usage
Architecture for World Wide Web applications in major
programming languages.
Web frameworks such as Django and Rails.
Model-view-controller pattern
9. Blackboard pattern
This pattern is useful for problems for which no
deterministic solution strategies are known. The blackboard pattern consists of
3 main components.
blackboard — a structured global memory containing objects
from the solution space
knowledge source — specialized modules with their own
representation
control component — selects, configures and executes
modules.
All the components have access to the blackboard. Components
may produce new data objects that are added to the blackboard. Components look
for particular kinds of data on the blackboard, and may find these by pattern
matching with the existing knowledge source.
Usage
Speech recognition
Vehicle identification and tracking
Protein structure identification
Sonar signals interpretation.
Blackboard pattern
10. Interpreter pattern
This pattern is used for designing a component that
interprets programs written in a dedicated language. It mainly specifies how to
evaluate lines of programs, known as sentences or expressions written in a
particular language. The basic idea is to have a class for each symbol of the
language.
Usage
Database query languages such as SQL.
Languages used to describe communication protocols.
Interpreter pattern
Comparison of Architectural Patterns
The table given below summarizes the pros and cons of each
architectural pattern.
