CMU CS 15-675 Architectures for Software Systems Spring 1998
Evolution of Shared Information Systems
with answers
Garlan & Kazman Questions on Readings for Lecture 19 Due: Wed Mar 18, 1998
The papers:
[SG95]: Shaw &; Garlan, Chapter 4
[BCK]: Bass, Clements, Kazman, Chapter 7
Hints:
We begin today a discussion of data-centered repositories -- systems in which the chief issues have to do with managing a large body of information. Today’s reading deals with traditional databases and similar systems. Chapter 4 of Shaw and Garlan traces the development of one class of applications over time. Note both the evolutionary pattern and the appearance of this class of applications in numerous markets. Think about what this implies about "domain-specific" architectures.
Chapter 7 of Bass, Kazman, and Clements looks at the requirements and evolution of a specific shared information system architecture: that of the original software architecture for World-Wide Web applications. In particular, it looks at how the success of this system was driven by its software architecture and how the success in turn changed the requirements that drove the architecture.
Questions:
1) Describe the common evolutionary pattern of shared information systems. What forces drove evolution from one architecture to another?
(1) Isolated applications; (2) Batch sequential; (3) Repository; (4) Layered hierarchy
Isolated applications to batch sequential: need to eliminate manual operations for regularly-used sequences of steps
Batch sequential to repository: advent of on-line computing and need for interaction; also efficiency
Repository to layered hierarchy: need to merge multiple repositories, especially with repositories distributed across many machines.
3) What were the lessons learned as a result of building libWWW?
Formalized APIs are required; Functionality must be layered;
APIs must support a dynamic, open-ended set of features; APIs must be thread safe.Modified: 5/21/98