1  pi calculus

[1] Resource Access Control in Systems of Mobile Agents

[2] Pi Calculus Versus Petri Nets

 

 

 

1 pi calculus

[1-] Resource Access Control in Systems of Mobile Agents

MATTHEW HENNESSY AND JAMES RIELY

ABSTRACT.

 We describe a typing system for a distributed p-calculus which guarantees that distributed
agents cannot access the resources of a system without first being granted the capability to
do so. The language studied allows agents to move between distributed locations and to augment
their set of capabilities via communication with other agents. The type system is based on the novel
notion of a location type, which describes the set of resources available to an agent at a location.
Resources are themselves equipped with capabilities, and thus an agent may be given permission
to send data along a channel at a particular location without being granted permission to read data
along the same channel. We also describe a tagged version of the language, where the capabilities
of agents are made explicit in the syntax. Using this tagged language we define access violations as
runtime errors and prove that well-typed systems are incapable of such errors.

 

 

 

 

[2] Pi Calculus Versus Petri Nets
Let us eat "humble pie" rather than further inflate the "Pi hype"
Wil van der Aalst

 

Abstract    
In the context of Web Service Composition Languages (WSCLs), there is on ongoing debate on
the best foundation for Process-Aware Information Systems (PAIS’s): Petri nets or Pi calculus.
Example of PAIS’s are Workflow Management (WFM), Business Process Management (BPM),
Business-to-Business (B2B), Customer Relationship Management (CRM), and Enterprise
Resource Planning (ERP) systems. Clearly, the web service paradigm will change the
architecture of these systems dramatically. Triggered by industry standards such as SOAP,
WSDL, UDDI, etc., standards are being proposed for orchestrating web services. Examples of
such WSCLs are BPEL4WS, BPML, WSFL, WSCI, WS-CDL, and XLANG. In the debate on Petri
nets versus Pi calculus, many players in the "WSCL marketplace" are using demagogic
arguments not based on concrete facts. This short note is an attempt to create a more mature
discussion on the pros and cons of Petri nets and Pi calculus for WSCLs. A simple example is
given to illustrate fundamental differences between Petri nets and Pi calculus. The paper also
states seven challenges, in particular for those advocating the use of Pi calculus. Hopefully, this
note will contribute to expose the people who try to "hype" things like Pi calculus only for
marketing purposes. Note that the big discrepancy between the "Pi-hype" and reality will not only
limit the applicability of WSCLs but will also discredit a beautiful scientific framework like Pi
calculus.

Key words: Web Service Composition Languages, Petri nets, Pi calculus, BPEL4WS, BPML,
WSFL, XLANG, WS-CDL, and WSCI.

1 Introduction

    two challenges

   

2 History Of PAIS’s And Concurrency

   Robin Milner

   three achievements:

   (1) LCF, the mechanization of Scott's Logic of Computable Functions, probably the first theoretically based, yet practical tool for
machine assisted proof construction;

   (2) ML, the first language to include polymorphic type inference together with a type-safe exception-handling mechanism;

    (3) CCS, a general theory of concurrency.

 

 

   CCS -> CSP -> ACP

 

 

   One of the big misconceptions about Petri nets versus process algebras is that process algebras

are compositional while Petri nets are not. This is complete nonsense!

 

3 An Example

   

4 Towards A More Mature Discussion

 

   six categories:

   --

 

5 Conclusion

 

   three good reasons for using Petri nets as a basis for WSCL:

 

 

 

   

pi-演算—动态耦合系统的模型