Chapter 5 Distributed Systems: The Overall Architecture Presented by: Matt Carver Amber Martin Jon Tucker

Part I 4 Attributes of Distributed Systems 1. Where is the processing done? Distributed processing is the ability for more than one interconnected processor to be operating at the same time, typically for processing an application on more than one computer. 2. How are the processors and other devices interconnected? Connectivity among processors means that each processor in a distributed system can send data and messages to any other processor through electronic communications links. A good structure for reliable distributed systems has at least 2 independent paths between any two nodes, enabling an automatic alternate routing in case one node is down.

4 Attributes of Distributed Systems (cont.) 3. Where is the information stored? Distributed databases are being defined at least 2 ways. One divides a database and distributes its portions throughout a system, without duplicating the data. A network administrator can access any portion from any node (authorization). The second type of distributed database stores the same data at several locations, with one site containing the master file. 4. What rules or standards are used? Systemwide rules mean that an operating discipline for the distributed system has been developed and is enforced at all times. These rules govern communication between nodes, security, data accessibility, program and file transfers, and common operating procedures.

Part II 6 Types of Distributed Systems 1. Host-Based Hierarchy Mainframe (HP 3000) that does MRP Terminals are connected to the mainframe

2. Decentralized Stand-Alone Systems Big company with 3 departments Accounting, Manufacturing, and IT “sneaker net” Walk around from dept to dept with a floppy 6 Types of Distributed Systems (Cont.)

3. Peer-to-Peer LAN-Based Systems PCs, print servers, and gateways Everyone is equal….no superior system No hierarchy

6 Types of Distributed Systems (Cont.) 4. Hybrid Enterprisewide Systems LAN (High Point) 2 other LANs (Winston and Greensboro)

6 Types of Distributed Systems (Cont.) 5. Client-Server Systems Old days, one-tier model, housed data, logic, and presentation Company hired 2 people (accountants) to access the same data, the company had to go to 2-teir Marsh has a program called Ultipro. SQL Server housed Ultipro’s data 2 client PCs can access the server to get the data at the same time = 2 tier In the future, we may have to develop an application that needs access not only to the Ultipro data, but to the logic…we would implement a 3 tier approach SQL Serv still holds Ultipro’s data, and we put Ultipro’s logic on Marsh 1NT

6. Internet-Centric Computing Same as Host based system Use TCP/IP instead of serial connections 6 Types of Distributed Systems (Cont.)

Part III Roles and Components of an Enterprise Architecture Framework 1. Planner - Scope 2. Owner - Enterprise Model 3. Designer – Information System Model 4. Builder – Technology Model 5. Subcontractor - Components 6. Consumer/User – Functioning System 1. Data – what? 2. Function – how? 3. Network – where? 4. Who – people 5. When – time 6. Why – motivation

Use of the Framework Models are important because:  Allow proper evaluation of the packages  Help builders align with what owners want  Help companies realize what changes need to be made when they move to a new model Problems occur when IS or users bring in a package that follows a different data model  If the rules in that model are inconsistent with the rules in the company, then a lot of time will be wasted fixing the package

Part IV Four Types of IT Investments 1. Strategic – aim to change the way a firm competes, the products or services it offers, or how it intends to increase revenues 2. Informational – provide information employees need to manage and control the enterprise

Four Types of IT Investments 3. Transactional – support operational management; intended to cut operating costs by substituting capital for labor so higher volumes can be handled without huge increases in staff 4. Infrastructure – provide the base foundation of IT capability, supports all other levels applications

Part V What is an IT Infrastructure? An IT infrastructure is the foundation of an enterprise’s IT portfolio Provides both the managerial and technical expertise to successfully manage an enterprise Linked to other industry infrastructure systems such as banking payment systems and airline reservation systems

Elements of an IT Infrastructure Can include but not limited to: - Company-wide networks - Data Warehouses - Large-Scale Computing Facilities - Electronic Data Interchange - R&D for identifying emerging technologies

Three views of Infrastructure 1. Economies of scale (Utility) 2. Support for business programs (Dependent) 3. Flexibility to meet changes in the marketplace (Enabling)

Utility View Companies that view their infrastructure as a utility see it as an unavoidable service Expected benefits from cost saving achieved through economies of scale Organizations with this view try to minimize expenses of the infrastructure Only results in lowering cost, not reengineering the business

Dependent View Focuses on short-term business benefits Firms with this view see the network as critical This view smoothes the way for simplifying business procedures Infrastructure is seen as a business expense

Enabling View Most strategic of the three views Focuses on developing and continually modifying the infrastructure Aligns the infrastructure with the business strategy Primary benefit is long-term flexibility Infrastructure cost are seen as business investments rather than business expenses

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