DeleGate: A general purpose application level gateway

  • Yutaka Sato
  • Yoichi Hamazaki
Session C-4: Application Gateways
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1274)


DeleGate is a general purpose application level gateway which relays a variety of application protocols on the Internet, including HTTP, FTP, Gopher, WAIS, NNTP, SMTP, POP, Telnet, X Window and CU-SeeMe. It overcomes a variety of obstacles on the Internet caused by barriers for security, insufficient band width and mismatching among protocol specifications and implementations.

An application level gateway mediates communication between clients and servers recognizing the syntax and semantics of application protocols it is relaying. Therefore it can supply various functions like caching and translation to an application protocol, for its procedure and data, without changing clients and servers.

This paper presents an overview of DeleGate and its two unique features termed mounting and connection cache. Mounting is a mechanism which provides a virtual view for a name space of networked resources by filtering, aliasing and merging names from original name spaces. Resource names transferred as data on each protocol are recognized and rewritten by DeleGate. Connection cache allows established connections to servers to be resources which are sharable and reusable among clients. It reduces the cost of repetitive connection establishments to the same server, where the repetition is introduced by an application protocol gateway which relays between different protocols.


Round Trip Time Request Message Proxy Server Virtual View Application Protocol 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. 1.
    Chapman, D., B. and Zwicky, E., D.: Building Internet Firewalls, O'Reilly & Associates, Inc. (1995)Google Scholar
  2. 2.
    Avolio, F., M. and Ranum, M., J.: A Network Perimeter with Secure External Access, Proceedings of the Internet Society Symposium on Network and Distributed System Security (1994)Google Scholar
  3. 3.
    Luotonen, A. and Altis, K.: World-Wide Web Proxies, The First International WWW Conference (1994)Google Scholar
  4. 4.
    Squid Internet Object Cache, Scholar
  5. 5.
    Thau, R.: Design considerations for the Apache Server API, The Fifth International WWW Conference (1996).Google Scholar
  6. 6.
    Glassman, S.: A Caching Relay for the World Wide Web, The First International WWW Conference (1994)Google Scholar
  7. 7.
    Abrams, M., Standridge, C. R., Abdulla, G., Williams, S., and Fox, E. A.: Caching Proxies: Limitations and Potentials, The Fourth International WWW Conference (1995)Google Scholar
  8. 8.
    Berners-Lee, T., Fielding, R., and Frystyk, H.: Hypertext Transfer Protocol — HTTP/1.0, RFC1945 (1996)Google Scholar
  9. 9.
    Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Berners-Lee, T.: Hypertext Transfer Protocol — HTTP/1.1, RFC2068 (1997)Google Scholar
  10. 10.
    Berners-Lee, T., Masinter, L. and McCahill, M.: Uniform Resource Locators (URL), RFC1738 (1994)Google Scholar
  11. 11.
    Berners-Lee, T. and Connolly, D.: Hyper Text Markup Language — 2.0, RFC1866 (1995)Google Scholar
  12. 12.
    Freed, N. and Borenstein, N.: Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies, RFC2045 (1996)Google Scholar
  13. 13.
    Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D., Jones, L.: SOCKS Protocol Version 5, RFC1928 (1996)Google Scholar
  14. 14.
    Postel, J. and Reynolds, J.: File Transfer Protocol, RFC959 (1985)Google Scholar
  15. 15.
    Padmanabhan, V. N., and Mogul, J. C.: Improving HTTP Latency, The Second International WWW Conference (1994)Google Scholar
  16. 16.
    Nielsen, H. F., et al.: Network Performance Effects of HTTP/1.1, CSS1, and PNG. WWW Technical Report, NOTE-pipelining-970214 (1997)Google Scholar
  17. 17.
    Sato, Y.: Development of a Protocol Mediation System DeleGate, Electrotechnical Laboratory Technical Report, TR-94-17 (1994)Google Scholar
  18. 18.
    Sato, Y.: Features of Multipurpose Proxy Server DeleGate, INTERFACE, Vol.21, No.9 (1995) 130–146Google Scholar
  19. 19.
    Sato, Y.: Fundamental Technologies and Applications of Internet Firewalls — Construction of DeleGate, Computer Software, Vol.14, No.1 (1997) 55–63Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • Yutaka Sato
    • 1
  • Yoichi Hamazaki
    • 1
  1. 1.Computer Science Division, Electrotechnical LaboratoryIbarakiJapan

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