Enhancement through extension: the extension interpreter

Abstract

The ability to extend programs dynamically has clear advantages. However, providing efficient yet sufficiently flexible support for such capabilities system-wide presents significant challenges. We describe a design and implementation of an extension mechanism that depends heavily on interpretive techniques, including call arbitration, dynamic linking, and multilanguage extensions. We discuss these mechanisms in the context of our Extension Interpreter, which embodies our ideas and provides a framework for discussing the efficiency and generality of the implementation. Our current implementation runs under BSD UNIX 4.2 and 4.3 on VAXes and SUN workstations. Extensions can be written in both C and in Icon, demonstrating our ability to address problems both of compiled and interpreted languages.

References

1. [1] B. N. Bershad, D. T. Ching, E. D. Lazowska., J. Sanislo, and M. Schwartz. A Remote Procedure Call Facility for Heterogeneous Computer Systems. Technical Report 86-09-10, Department of Computer Science, University of Washington (Sep. 1986). To appear, IEEE Trans. on Softw. Engineering.
2. [2] A. D. Birrell and B. J. Nelson. Implementing Remote Procedure Calls. ACM Transactions on Computer Systems 2,1 (Feb. 1984).
3. [3] A. P. Black, E. D. Lazowska, H. M. Levy, D. Notkin, J. Sanislo, and J. Zahorjan. Interconnecting Heterogeneous Computer Systems. Tech. Rep. 87-01-02, Dept. of Comp. Sci., Univ. of Washington (Jan. 1987).
4. [4] S. R. Bourne. An Introduction to the UNIX Shell. Bell Syst. Tech. J. 57, 6, pp. 2797-2822 (Jul.-Aug. 1978).
5. [5] R. Cohn. Command Languages for Window Systems. Thesis proposal., Dept. of Comp. Sci., Carnegie-Mellon Univ. (Apr. 1986).
6. [6] J. Gosling. UNIX Emacs. Unipress (1981).
7. [7] J. Gosling. SunDew: A Distributed and Extensible Window System. Proc. 1986 Winter USENIX Tech. Conf., pp. 98-103 (1986).
8. [8] A. Goldberg and D. Robson. Smalltalk- 80: The Language and its Implementation. Addison-Wesley, Reading MA (1983).
9. [9] R. E. Griswold and M. T. Griswold. The Icon Programming Language Prentice-Hall Inc., Englewood NJ, (1983).
10. [10] R. E. Griswold. Personalized Interpreters for Version 6 of Icon. Tech. Rep. TR-86-12b, Dept. of Comp. Sci., Univ. of Arizona (May 1986).
11. [11] R. Hayes and R. D. Schlichting. Facilitating Mixed-Language Programming in Distributed Systems. To appear, IEEE Trans. on Softw. Engineering.
12. [12] IBM Virtual Machine/System Product. CMS Command and Macro Reference. SC19- 9209.
13. [13] M. B. Jones, R. F. Rashid, and M. R. Thompson. Matchmaker: An Interface Specification Language for Distributed Processing, Proc. 12th ACM Symp. on Principles of Programming Languages (Jan. 1985).
14. [14] W. Joy. An Introduction to the C shell. In UNIX User's Manual: Supplementary Documents (Mar. 1984).
15. [15] J. L. Keedy and J. V. Thomson. Command Interpretation and Invocation in an Information-Hiding System. In The Future of Command Languages: Foundations for Human-Computer Communication. IFIP WG 2.7 Working Conf. (Sep. 1985).
16. [16] D. E. Knuth. The TEXTbook. Addison-Wesley (1984).
17. [17] W. Mitchell. An Icon Subsystem for UNIX Emacs. TR 84-8, Dept. of Comp. Sci., Univ. of Arizona (May 1984).
18. [18] D. Notkin, W. G. Griswold, and M. Donner. Large Enhancement through Extension: Analysis and Experiments. Tech. Rep. 87-03- 03, Dept. of Comp. Sci., Univ. of Washington (Mar. 1987).
19. [19] D. L. Parnas. Designing Software for Ease of Extension and Contraction. IEEE Trans. on Softw. Eng. SE-5, 2 (Mar. 1979).
20. [20] R. Reich. The Macro Maker. MacUser 1, 2 (December 1985).
21. [21] B. K. Reid and J. H. Walker. Scribe Introductory User's Manual. Third Edition (1980).
22. [22] R. M. Stallman. EMACS - The Extensible, Customizable, Self-Documenting Display Editor. Proc. of the ACM Sigplan/Sigoa Symp. on Text Manip., pp. 147-156 (Jun. 1981). Appears as Sigplan Notices 16, 6 (Jun. 1981).

Index Terms

• Computer systems organization

  • Architectures

    • Distributed architectures

      • Client-server architectures

• Information systems

  • Data management systems

    • Middleware for databases

      • Application servers

      • Database web servers

• Social and professional topics

  • Professional topics

    • Computing industry

      • Industry statistics

• Software and its engineering

  • Software creation and management

    • Software development techniques

      • Reusability

  • Software notations and tools

    • Compilers

      • Interpreters