Mobile Resource Guarantees for Grid Applications
Stephen Gilmore
Grids and Applied Language Theory Workshop
National e-Science Centre
16th October 2003
Stephen Gilmore
Mobile Resource Guarantees for Grid Applications — GALT’03
16th October 2003
3
Overview
• The Mobile Resource Guarantees project has developed a framework for
predicting resource consumption (space or time) of programs and expressing
this as a proof about the program.
– Proofs are unforgeable;
– proof checking is easy even if proof generation is hard;
– the properties in question are modest.
• Potential applications of the MRG technology include global computing
applications where users wish to protect against (potentially) harmful
downloaded code and resource-sharing systems where service providers wish to
optimise utilisation of high-performance systems.
Stephen Gilmore
Mobile Resource Guarantees for Grid Applications — GALT’03
16th October 2003
3
Resource-bounded mobile code
Machine A
Machine B
proof
checker
source code
program
Resource policy r
Code c with certificate p
compiler
resource
typechecker
Stephen Gilmore
resource
manager
p ⇒c ` r
virtual
machine
certificate
generator
Mobile Resource Guarantees for Grid Applications — GALT’03
Runs code c
16th October 2003
4
Sites and personnel
LFCS,
University of Edinburgh
Ludwig-Maximilians-Universität,
München
David Aspinall, Stephen Gilmore,
Don Sannella, Ian Stark
Martin Hofmann
(& Roberto Amadio)
Lennart Beringer, Kenneth MacKenzie
Michal Konečný, Alberto Momigliano
Hans-Wolfgang Loidl, Olha Shkaravska
Robert Atkey, Brian Campbell,
Allan Clark, Panagiota Karadmitriou
Laura Korte, Matthew Prowse,
Nicholas Wolverson, . . .
Steffen Jost, . . .
Type systems for resource bounded
programming and compilation
(RESBND project)
Stephen Gilmore
Mobile Resource Guarantees for Grid Applications — GALT’03
16th October 2003
5
MRG technology
• The MRG technology consists of programming languages; type systems for the
languages; logics for expressing statements of resource consumption; and proof
technology for proving these statements.
– Camelot, a high-level functional programming language with objects and
resource control;
– Grail, a strongly-typed intermediate language which is the target language
of the Camelot compiler and is interconvertible with Java byte code;
– A cost model, a formal semantics for byte code execution which tracks
execution time and space allocation;
– A byte code logic allowing the expression of costs, embedded in a generic
proof system (Isabelle).
Stephen Gilmore
Mobile Resource Guarantees for Grid Applications — GALT’03
16th October 2003
6
Camelot: functions with resource control
(* A function to increment a list in-place *)
let incList l =
match l with
[]
-> []
| (h::t)@a -> (h + 1)::(incList t)@a
(* A function to sum a list and de-allocate it *)
let sumList l =
match l with
[]
-> 0
| (h::t)@ -> h + (sumList t)
Stephen Gilmore
Mobile Resource Guarantees for Grid Applications — GALT’03
16th October 2003
7
Grail: analysable byte-code
method public static int sumList (List l) =
let
fun f sumList(List l) =
if l = null[List] then f 0() else f 1(l)
(* Base case: the list is empty *)
fun f 0() = 0
(* Step case: the list is non-empty *)
fun f 1(List l) =
let
val h = getfield l <int List.hd>
val t = getfield l <List List.tl>
val () = invokestatic <void List.free (List)> (l)
val res = invokestatic <int Lists2.sumList (List)> (t)
in add h res end
in f sumList(l) end
Stephen Gilmore
Mobile Resource Guarantees for Grid Applications — GALT’03
16th October 2003
8
MRG and e-Science: From Kilobytes to Petabytes
• Camelot and Grail programs can run in very resource-constrained environments
such as the KVM. What is the relevance to Grids?
• Grid service providers need to schedule competing requests for access to
resources. A specification language for resources exists (RSL) which could be
an MRG compiler output.
• The use of mobile code technology seems a good match for Grids. With 25Kb
of code and 1Pb of sky survey data it is infeasible to ship the data to the code.
• There are projects which have supported scientific programming in functional
languages (e.g. Psicho). An alternative would be to transfer the MRGtechnology to Java or Java-like languages (ESC/Java, SpecialJ, and Pizza).
Stephen Gilmore
Mobile Resource Guarantees for Grid Applications — GALT’03
16th October 2003
9
Pointers
RESBND Type Systems for Resource Bounded Programming and Compilation
http://www.dcs.ed.ac.uk/home/resbnd/
MRG Mobile Resource Guarantees
http://www.dcs.ed.ac.uk/home/mrg/
ReQueST Resource Quantification in e-Science Technologies
http://homepages.inf.ed.ac.uk/stg/grants/REQUEST/
Stephen Gilmore
Mobile Resource Guarantees for Grid Applications — GALT’03
16th October 2003