Quote: protect the kernel from extension modules by loading each module into a less privileged segment within kernel space [»chiuTC3_1999]

Quote: for extensible systems, separate access control into an enforcement manager and policy manager; inspects extensions for protected types and operations; protection domain transfers and audits [»grimR2_2001]

Quote: protection domain transfers take 200 instructions compared to 50 for the event dispatcher; need to limit use, e.g., separate web server from NFS and file cache operations [»grimR2_2001]

Quote: Capability Language (CL) propagates capabilities for region-based memory operations; provably safe type system; lexical scope not required; e.g., extensible systems and continuation-passing style [»walkD7_2000]

Quote: most systems for untrusted extensions assume a trusted garbage collector; use Capability Language to verify memory management [»walkD7_2000]

Quote: SPIN OS provides language-based, fine-grained access control and fine-grained user extensions; static type checking and dynamic linking [»bersBN12_1995]

Quote: SPIN depends only on Modula-3's interfaces, type safety, and automatic memory management; no dangling pointers or array overflow [»bersBN12_1995]

Quote: use page protection to provide access to shared libraries from user-level extensions; data/function pointers stay the same; applications control which pages are accessible [»chiuTC3_1999]

Quote: use 'ret' to call a less-privileged extension, and 'call' to return from the extension [»chiuTC3_1999]

Quote: an Emacs library is a publication medium for users to share their extensions without interference

Quote: user customization allows the whole user community to participate in modifying the system [»stalRM6_1981]

Quote: open systems must be designed so that operating components take over from failed components during repair [»hewiC7_1986]

Quote: do not use shared memory or call-by-reference for extensible systems; use multiple return results and call-by-value/result

Quote: extensible systems run core system services and dynamically composed extensions in the same address space using low-latency, type-safe interfaces [»grimR2_2001]

Quote: SPIN uses Modula-3 to guarantee that an extension's interface is obeyed; compiler is part of trusted computing base [»grimR2_2001]

Quote: extension modules can access the kernel through a specialized system-call interface; but normally, extensions should be self-contained [»chiuTC3_1999]

Quote: the kernel and extension modules share a read-write memory region for non-sensitive data; e.g., packet headers [»chiuTC3_1999]

Quote: fast breakpoints by invoking a closure assembled from the original instruction; requires atomic writes to code [»kessPB6_1990]

Quote: Oberon is extensible; e.g., any application can read text from the screen by importing the type Text [»wirtN9_1989]

Quote: Smalltalk provides a simple semantics and syntax for the creation of domain-specific programming systems [»goldA10_1995]

Quote: because of Java's late binding it is easy to change methods and private variables; just need to retain old methods or their type signatures [»goslJ6_1997]

Quote: Forth was designed to replace the "vast hierarchy" of software tools with a simple, natural programmer-to-Forth interface [»rathED_1996]