8/28/97Information Organization and Retrieval Intergalactic Courier Service: Database and Application Design University of California, Berkeley School of Information Management and Systems SIMS 202 & 206

8/28/97Information Organization and Retrieval Database Design Process Conceptual Model Logical Model External Model Conceptual requirements Conceptual requirements Conceptual requirements Conceptual requirements Application 1 Application 2Application 3Application 4 Application 2 Application 3 Application 4 External Model External Model External Model Internal Model 1. Needs assessment 2. Requirements analysis 3. Data identification 4. Conceptual Design 6. Testing 5. Internal/Physical Design

8/28/97Information Organization and Retrieval Requirements analysis Functional requirements –What services/activities does the database and system need to support? Performance requirements –How fast must the system be able to fulfill its functions? –What volume of transactions must be handled? Reliability requirements –What are the requirements for accuracy? –What is acceptable down-time? –What maintenance is required?

8/28/97Information Organization and Retrieval Functional Requirements Support routing of packages (Basic function) Support tracking of packages en route –Query location of package by tracking number (GPS?) –Query location of packages by shipper or addressee Confirm delivery/receipt (signatures) Support multiple priorities and shipping times Support destination changes en route Support arrival time estimates Support rescheduling of missed deliveries

8/28/97Information Organization and Retrieval Functional Requirements Support on-the-fly dispatching of closest trucks for high-priority pickups Reports (accessible online by management) –Per truck daily delivery numbers –Volume and destinations on a city by city basis –Delivery failure statistics because no addressee available because of shipping delays –Others?

8/28/97Information Organization and Retrieval Performance Requirements Must support 2 major routing centers (Los Angeles and Chicago). Must support 20 local routing centers scattered across the country. Must support 200 trucks handling local pickup and deliveries.

8/28/97Information Organization and Retrieval Performance Requirements System must be able to support 20,000 packages per day currently and more as business grows. Must be able to query current location of a package and get a response in under 5 seconds. Must be able to query for arrival time and get estimate within 20 seconds.

8/28/97Information Organization and Retrieval Performance Requirements System must be available continuously during business hours (East and West coast), and preferably 7x24. Scheduled system maintenance should be able to be performed only during non- business hours.

8/28/97Information Organization and Retrieval Performance Requirements Backup systems in case of primary system failure. Data backup at multiple locations. Recovery from severe failures (e.g. disk crashes) within 2 hours. (emergency maintenance) Recovery from catastrophic failures (e.g. flood, fire) within 5 hours at secondary location

8/28/97Information Organization and Retrieval Database Design Process Conceptual Model –Merge the collective needs of all applications –Determine what Entities are being used Some object about which information is to maintained –What are the Attributes of those entities? Properties or characteristics of the entity What attributes uniquely identify the entity –What are the Relationships between entities How the entities interact with each other?

8/28/97Information Organization and Retrieval Developing a Conceptual Model Overall view of the database that integrates all the needed information discovered during the requirements analysis. Elements of the Conceptual Model are represented by diagrams, Entity- Relationship or ER Diagrams, that show the meanings and relationships of those elements independent of any particular database systems or implementation details.

8/28/97Information Organization and Retrieval Entity An Entity is an object in the real world (or even imaginary worlds) about which we want or need to maintain information –Persons (e.g.: customers in a business, employees, authors) –Things (e.g.: purchase orders, meetings, parts, companies) Employee

8/28/97Information Organization and Retrieval Attributes Attributes are the significant properties or characteristics of an entity that help identify it and provide the information needed to interact with it or use it. (This is the Metadata for the entities.) Employee Last Middle First Name SSN Age Birthdate Projects

8/28/97Information Organization and Retrieval Relationships Relationships are the associations between entities. They can involve one or more entities and belong to particular relationship types Examples derived from David R. McClanahan “Conceptual Design” DBMS Magazine January 1992, and “Hands-on Design”, February 1992.

8/28/97Information Organization and Retrieval Relationships Class Attends Student Part Supplies project parts Supplier Project

8/28/97Information Organization and Retrieval Types of Relationships Concerned only with cardinality of relationship Truck Assigned Employee Project Assigned Employee Project Assigned Employee 11 n n 1 m

8/28/97Information Organization and Retrieval More Complex Relationships Project Evaluation Employee Manager 1/n/n 1/1/1 n/n/1 Manages Employee Project Assigned Employee 4(2-10)1 SSNProjectDate Manages Is Managed By 1 n