Chapter 10 - System Architecture

Architecture Checklist

  • Key factors: corporate culture, ERP alignment, TCOscalability, Web integration, legacy interfaces, processing mode, security, portals.

ERP (Enterprise Resource Planning)

  • Establishes enterprise-wide IT architecture & standards.

  • Often extended through Supply Chain Management (SCM).

Cost of Ownership

  • TCO = purchase + fees/contracts (hard costs).

  • Evaluate both initial and ongoing costs during planning.

Scalability & Integration

  • Scalability: ability to grow, shrink, or change easily.

  • Web-centric design eases e-commerce integration.

  • New systems may need data-format compatibility with legacy systems.

System Functions Placement

  • Core functions: processing logic, data storage/access, user interface.

  • Design determines where each function executes (client, server, Web).

Evolution of Architecture

  • Mainframe era: centralized server with remote terminals.

  • PC era: stand-alone productivity.

  • Networking: LAN for local sharing; WAN links distant LANs.

Client/Server Architecture

  • Processing split between clients & central server.

  • Fat (thick) client: logic on client.

  • Thin client: logic on server (better performance).

  • 2-tier: UI on client, data on server, logic anywhere.

  • 3-tier (n-tier): UI → application server → data server.

  • Middleware ("glueware") enables tier communication.

  • Performance: avoid hitting the "knee of the curve"; use DDBMS for load distribution.

Internet Impact

  • Web server supplies HTML UI → simpler clients, lower cost.

  • Cloud computing: third-party hosted software/data, on-demand scaling.

  • Web 2.0: user collaboration (wikis, social media); step toward semantic Web.

E-commerce Architecture

  • In-house: unique branding, full control, scalable, easy system integration.

  • Packaged solutions: ready-made, lower complexity for mid/large firms.

  • Service providers / ASP: subscription access, outsourcing option.

Processing Methods

  • Online: real-time processing & feedback.

  • Batch: grouped processing on schedule; reduces peak load; good for audit/security.

  • Mixed model common (e.g., POS daily summaries).

Network Fundamentals

  • OSI model: standards for interoperable networking.

  • Topologies: hierarchical, bus, ring, star, mesh (high redundancy).

  • Devices: Router (path selection/segment linking), Proxy server (LAN ↔ Internet).

Wireless Networking

  • Standards: IEEE 802.11 family; MIMO boosts throughput.

  • Topologies: Basic Service Set, Extended Service Set.

  • Trends: Wi-Fi Alliance certification; Bluetooth for short range links.

SDLC Design Phase Completion

  • Deliverable: System Design Specification (design, cost, schedule baseline).

  • Main sections: mgmt summary, components, environment, implementation reqs, time/cost, appendices.

  • User approval: verify UI, reports, screens; continuous feedback.

  • Presentations: technical staff → users → management for final decision.