Asper School of Business
University of Manitoba
Systems Analysis & Design
Instructor: Bob Travica
System architectures
Updated: November 2014
Outline
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Single computer architecture
Client-Server architecture
N-Tier Client-Server architecture
Middleware
Centralized & Distributed architecture
Computer networks
The Internet, Intranets, and Extranets
Internet-based architectures
Services Oriented Architecture
Cloud computing and system architectures
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Single-computer architecture
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Architecture (of system, network) = overall
design, blue print, “look”, “big picture”
Single system attached to peripheral
devices (e.g., mainframe-based)
Advantages: easier to design, build,
operate, maintain
Disadvantages: limits in terms of capacity,
and software/hardware standards
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Client-Server architecture
Some processing;
User interface
(Fat client)
Some processing;
User interface
(Fat client)
User interface
(Thin client)
Data storage;
Some processing
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Client: requestor of resources or services from a
server
Server: responder to Client’s requests
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Architectural issues—who manages:
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 Data
 Processing (functionality)
 User interface
Software only, or software+hardware (dedicated computer)
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Client-Server architecture
(cont.)
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Client and server communicate via welldefined protocols over a physical channel
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Client/server architecture advantages:
 Location flexibility, scalability,
maintenance
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Client/server architecture disadvantages
 Additional complexity, potential reliability
issue, security issues
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N-Tier architecture
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Partitions system into less tightly coupled
segments
3-tiers (layers) frequent, placing each of 3
services on a different hardware:
Function request
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The data layer
The business logic layer (functionality)
The view/presentation layer (user interface)
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Middleware
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Middleware
 The middle layer in 3-tier architecture can also
contain drivers for back-end DBs (system
interface)
 Can be object-based while other layers are not
(legacy systems, relational databases)
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Computer networks
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Support distributed system architecture (clientserver)
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LAN vs. WAN
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Computer data transfer capabilities:
 Enable data transfer (e.g., remote database
access, remote login)
 Provide infrastructure for human
communication systems
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Network architecture issues
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Issues:
 Communication protocols (net software, Ethernet,
TCP/IP…)
 Network configuration (bus, star, wheel, mesh)
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Ensuring sufficient network capacity
Security
Mesh
Domain of Network Administrator (a highly demanded IS
position)
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The Internet, Intranets, & Extranets
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Internet: LANs, WANs, and individual devices
connected via TCP/IP software
The Web: Collection of resources accessed over the
Internet; specific addressing scheme
Intranet: private net accessible to internal users
Extranet: intranet extended to include some external
users
Virtual private network: uses public network as if it is
private
Internet-based architectures
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Web is uses client/server architecture
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Characteristics:
 Web resources are managed by server
 Clients get services from servers
 Web protocols define valid resource formats and
communication standards
 Object-based software
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SOA (next slides)
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Services Oriented Architecture (SOA)
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SOA is a set of methods designing and developing application
software in the form of interoperable services (apps).
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Services are functions that are built as software components pieces of code or data structures.
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Services can be used for different purposes, in different apps
(Example: Web services, as a foreign language spell checker
for a word processor system; mashups as in Google maps).
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SOA draws on component software, object oriented approach,
modular programming, distributed computing, cross-platform
computing, cloud computing (SaaS).
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SOA aims to allow users to assemble entire large programs
(also ad hoc in character).
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SOA
(more)
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SOA components are put together by a process of
orchestration using a list of SOA components needed.
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Components are called based on their interface (an instance
of system interface) which advertises a component's
functionality and protocols.
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Protocol describes messages to a component (e.g., what
data can be inputted to trigger the function the component
represents) – metadata.*
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SOA principles (see note) **
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SOA Benefits & Costs
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SOA Benefits:
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cost savings in system development
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more flexible software to meet changing business needs (ad
hos apps)
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more complex software possible without complexity & cost
demanded by the final functionality reached (e.g., mashups)
SOA Costs:
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integration of components (the interface issues)
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components' quality (testing, assurances)
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development continuity
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Internet-based architectures
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Advantages of Web/Internet:
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(cont.)
Flexibility, accessibility, low cost
communication, widely used standards
Disadvantages of Web/Internet:
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Security, reliability, throughput, quality,
volatile standards
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Cloud computing
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Cloud computing (Cloud) is a technical and business model
that complements or substitutes organizational information
systems.
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Some aspects of Cloud resemble client-server architecture,
but there is much more to it.
CLOUD
CLIENT
(USER)
host whole systems
host databases, development resources
CLOUD
VENDOR
host hardware, storage, virtual machines…
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Cloud services
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Cloud
computing
services
Cloud Client
Web browser, desktops computers,
mobile devices
Internet
Private
network
Software as a Service
accounting, customer relationship
management, human resource
management…
Platform as a Service
software development resources,
databases, servers
Infrastructure as a Service
computers, virtual machines, data storage,
virtual local area networks, firewalls
See Note below*
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Cloud effects
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Cloud builds on component software, OO methods,
computer networks.
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Cloud may enable new forms of organizing, as virtual
organization (VO).*
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