Abstract
Proxies are a common technique to virtualize objects in object-oriented languages. A proxy is a placeholder object that emulates or wraps another target object. Both the proxy’s representation and behavior may differ substantially from that of its target object.
In many OO languages, objects may have language-enforced invariants associated with them. For instance, an object may declare immutable fields, which are guaranteed to point to the same value throughout the execution of the program. Clients of an object can blindly rely on these invariants, as they are enforced by the language.
In a language with both proxies and objects with invariants, these features interact. Can a proxy emulate or replace a target object purporting to uphold such invariants? If yes, does the client of the proxy need to trust the proxy to uphold these invariants, or are they still enforced by the language? This paper sheds light on these questions in the context of a Javascript-like language, and describes the design of a Proxy API that allows proxies to emulate objects with invariants, yet have these invariants continue to be language-enforced. This design forms the basis of proxies in ECMAScript 6.
This is a preview of subscription content, log in via an institution to check access.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Eugster, P.: Uniform proxies for java. In: OOPSLA 2006: Proceedings of the 21st Annual Conference on Object-oriented Programming Systems, Languages, and Applications, pp. 139–152. ACM, NY (2006)
Austin, T.H., Disney, T., Flanagan, C.: Virtual values for language extension. In: Proceedings of the 2011 ACM International Conference on Object Oriented Programming Systems Languages and Applications, OOPSLA 2011, pp. 921–938. ACM, New York (2011)
Findler, R.B., Felleisen, M.: Contracts for higher-order functions. In: Proceedings of the Seventh ACM SIGPLAN International Conference on Functional Programming, ICFP 2002, pp. 48–59. ACM, New York (2002)
Pratikakis, P., Spacco, J., Hicks, M.: Transparent proxies for java futures. In: Proceedings of the 19th Annual ACM SIGPLAN Conference on Object-oriented Programming, Systems, Languages, and Applications, OOPSLA 2004, pp. 206–223. ACM, New York (2004)
ECMA International: ECMA-262: ECMAScript Language Specification. 5th edn. ECMA, Geneva, Switzerland (December 2009)
Fähndrich, M., Leino, K.R.M.: Heap monotonic typestates. In: International Workshop on Aliasing, Confinement and Ownership (IWACO 2003), pp. 58–72 (2003)
Van Cutsem, T., Miller, M.S.: Proxies: design principles for robust object-oriented intercession APIs. In: Proceedings of the 6th Symposium on Dynamic Languages, DLS 2010, pp. 59–72. ACM (2010)
Crockford, D.: Javascript: The Good Parts. O’Reilly (2008)
Guha, A., Saftoiu, C., Krishnamurthi, S.: The essence of javascript. In: D’Hondt, T. (ed.) ECOOP 2010. LNCS, vol. 6183, pp. 126–150. Springer, Heidelberg (2010)
Redell, D.D.: Naming and Protection in Extensible Operating Systems. PhD thesis, Department of Computer Science, University of California at Berkeley (November 1974)
Miller, M.S.: Robust Composition: Towards a Unified Approach to Access Control and Concurrency Control. PhD thesis, John Hopkins University, Baltimore, Maryland, USA (May 2006)
Miller, M.S., Samuel, M., Laurie, B., Awad, I., Stay, M.: Caja: Safe active content in sanitized javascript (June 2008), http://tinyurl.com/caja-spec
Hayes, B.: Ephemerons: a new finalization mechanism. In: Proceedings of the 12th ACM SIGPLAN Conference on Object-oriented Programming, Systems, Languages, and Applications, OOPSLA 1997, pp. 176–183. ACM, New York (1997)
Strickland, T.S., Tobin-Hochstadt, S., Findler, R.B., Flatt, M.: Chaperones and impersonators: run-time support for reasonable interposition. In: Proceedings of the ACM International Conference on Object Oriented Programming Systems Languages and Applications, OOPSLA 2012, pp. 943–962. ACM, New York (2012)
Blosser, J.: Explore the Dynamic Proxy API (2000), http://www.javaworld.com/jw-11-2000/jw-1110-proxy.html
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2013 Springer-Verlag Berlin Heidelberg
About this paper
Cite this paper
Van Cutsem, T., Miller, M.S. (2013). Trustworthy Proxies. In: Castagna, G. (eds) ECOOP 2013 – Object-Oriented Programming. ECOOP 2013. Lecture Notes in Computer Science, vol 7920. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-39038-8_7
Download citation
DOI: https://doi.org/10.1007/978-3-642-39038-8_7
Publisher Name: Springer, Berlin, Heidelberg
Print ISBN: 978-3-642-39037-1
Online ISBN: 978-3-642-39038-8
eBook Packages: Computer ScienceComputer Science (R0)