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S.Ducasse 1
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
Stéphane Ducasse
Stephane.Duca...
S.Ducasse 2
License: CC-Attribution-ShareAlike 2.0
http://creativecommons.org/licenses/by-sa/2.0/
S.Ducasse 3
Proxy
• Category
• Structural
• Intent
• Provide a surrogate or placeholder for another object to
control acce...
S.Ducasse 4
Proxy Pattern Motivation
S.Ducasse 5
Proxy Applicability
• A remote proxy provides a local representative for an
object in a different address spac...
S.Ducasse 6
Proxy Pattern Structure
S.Ducasse 7
Proxy Pattern Participants
• Proxy (ImageProxy)
• maintains a reference that lets the proxy access the real
su...
S.Ducasse 8
Proxy Participants (continued)
• Subject (Graphic)
• defines the common interface for RealSubject and Proxy
so...
S.Ducasse 9
Proxy Consequences
• Consequences
• A remote proxy can hide the fact that an object resides
in a different add...
S.Ducasse 9
Proxy Consequences
• Consequences
• A remote proxy can hide the fact that an object resides
in a different add...
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Stoop 437-proxy

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Transcript of "Stoop 437-proxy"

  1. 1. S.Ducasse 1 QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture. Stéphane Ducasse Stephane.Ducasse@univ-savoie.fr http://www.listic.univ-savoie.fr/~ducasse/ Proxy
  2. 2. S.Ducasse 2 License: CC-Attribution-ShareAlike 2.0 http://creativecommons.org/licenses/by-sa/2.0/
  3. 3. S.Ducasse 3 Proxy • Category • Structural • Intent • Provide a surrogate or placeholder for another object to control access to it • Also known as • Surrogate
  4. 4. S.Ducasse 4 Proxy Pattern Motivation
  5. 5. S.Ducasse 5 Proxy Applicability • A remote proxy provides a local representative for an object in a different address space • A virtual proxy creates expensive objects on demand • A protection proxy controls access to the original object, in order to enforce access rights • A smart reference is a replacement for a bare pointer that performs additional actions when an object is accessed
  6. 6. S.Ducasse 6 Proxy Pattern Structure
  7. 7. S.Ducasse 7 Proxy Pattern Participants • Proxy (ImageProxy) • maintains a reference that lets the proxy access the real subject • provides an interface identical to Subject’s so that a proxy can be substituted for the real subject • controls access to the real subject and may be responsible for creating and deleting it
  8. 8. S.Ducasse 8 Proxy Participants (continued) • Subject (Graphic) • defines the common interface for RealSubject and Proxy so that a Proxy can be used anywhere a RealSubject is expected • RealSubject (Image) • defines the real object that the proxy represents
  9. 9. S.Ducasse 9 Proxy Consequences • Consequences • A remote proxy can hide the fact that an object resides in a different address space • A virtual proxy can perform optimizations such as creating an object on demand • Both protection proxies and smart references allow additional housekeeping tasks when an object is accessed
  10. 10. S.Ducasse 9 Proxy Consequences • Consequences • A remote proxy can hide the fact that an object resides in a different address space • A virtual proxy can perform optimizations such as creating an object on demand • Both protection proxies and smart references allow additional housekeeping tasks when an object is accessed
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