Mutatis mutandis: safe and predictable dynamic software updating

Dynamic software updates can be used to fix bugs or add features to a running program without downtime. Essential for some applications and convenient for others, low-level dynamic updating has been used for many years. Perhaps surprisingly, there is little highlevel understanding or language support to help programmers write dynamic updates effectively. To bridge this gap, we present Proteus, a core calculus for dynamic software updating in C-like languages that is flexible, safe, and predictable. Proteus supports dynamic updates to functions (even active ones), to named types and to data, allowing on-line evolution to match source-code evolution as we have observed it in practice. We ensure updates are type-safe by checking for a property we call "con-freeness" for updated types t at the point of update. This means that non-updated code will not use t concretely beyond that point (concrete usages are via explicit coercions) and thus t's representation can safely chang...

• Type: Conference
• Year: 2005
• Where: POPL
• Authors: Gareth Stoyle, Michael W. Hicks, Gavin M. Bierman, Peter Sewell, Iulian Neamtiu
• Keywords: Dynamic Software, POPL 2005, Programming Languages, Syntax General Terms, Theory--Semantics