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Abstract We conceptualize adecentralizedsoftware application as one constituted fromautonomousagents that communicate viaasynchronousmessaging. Modern software paradigms such as microservices and settings such as the Internet of Things evidence a growing interest in decentralized applications. Constructing a decentralized application involves designing agents as independent local computations that coordinate successfully to realize the application’s requirements. Moreover, a decentralized application is susceptible to faults manifested as message loss, delay, and reordering. We contributeMandrake, a programming model for decentralized applications that tackles these challenges without relying on infrastructure guarantees. Specifically, we adopt the construct of aninformation protocolthat specifies messaging between agents purely in causal terms and can be correctly enacted by agents in a shared-nothing environment over nothing more than unreliable, unordered transport. Mandrake facilitates (1) implementing protocol-compliant agents by introducing a programming model; (2) transforming protocols into fault-tolerant ones with simple annotations; and (3) a declarative policy language that makes it easy to implement fault-tolerance in agents based on the capabilities in protocols. Mandrake’s significance lies in demonstrating a straightforward approach for constructing decentralized applications without relying on coordination mechanisms in the infrastructure, thus achieving some of the goals of the founders of networked computing from the 1970s. 

An interaction protocol specifies how the member agents of a decentralized multiagent system may communicate to satisfy their respective stakeholders' requirements. We focus on information protocols, which are fully declarative specifications of interaction and support asynchronous communication. We offer Mambo, an approach for protocol design. Mambo identifies common patterns of requirements, provides a notation to express them, and a verification procedure. Mambo incorporates heuristics to generate small internal representations for efficiency. Experimental results demonstrate Mambo's effectiveness on practical protocols. 

Protocols model multiagent systems (MAS) by capturing the communications between its agents. Belief-Desire-Intention (BDI) architectures provide an attractive way for organizing an agent in terms of cognitive concepts. Current BDI approaches, however, lack adequate support for engineering protocol-based agents. We describe Argus, an approach that melds recent advances in flexible, declarative communication protocols with BDI architectures. For concreteness, we adopt Jason as an exemplar of the BDI paradigm and show how to support protocol-based reasoning in it. Specifically, Argus contributes (1) a novel architecture and formal operational semantics combining protocols and BDI; (2) a code generation-based programming model that guides the implementation of agents; and (3) integrity checking for incoming and outgoing messages that help ensure that the agents are well-behaved. The Argus conceptual architecture builds quite naturally on top of Jason. Thus, Argus enables building more flexible multiagent systems while using a BDI architecture than is currently possible. 

Commitments support flexible interactions between agents by capturing the meaning of their interactions. However, commitmentbased reasoning is not adequately supported in agent programming models. We contribute Azorus, a programming model based on declarative specifications centered on commitments and aligned with information protocols. Azorus supports reasoning about goals and commitments and combines modeling of commitments and protocols, thereby uniting three leading declarative approaches to engineering decentralized multiagent systems. Specifically, we realize Azorus over three existing technology suites: (1) Jason, a popular BDI-based programming model; (2) Cupid, a formal language and query-based model for commitments; and (3) BSPL, a language and its associated tools for information protocols, including Jason programming. We implement Azorus and demonstrate how it enables capturing interesting patterns of business logic. 

We demonstrate Orpheus, a novel programming model for engineering BDI agents that communicate on the basis of protocols. In Orpheus, protocols are specified in BSPL and agents are implemented in Jason. Given a protocol, Orpheus tooling generates a Jason adapter that exposes a simple interface for sending messages based on protocol state. Orpheus shines in the implementation of flexible, loosely-coupled agents, long a challenge for BDI-based agent programming approaches. Demonstration video: https://di.unito.it/orpheusvid 

We propose Orpheus, a novel programming model for communicating agents based on information protocols and realized using cognitive programming. Whereas traditional models are focused on reactions to handle incoming messages, Orpheus supports organizing the internal logic of an agent based on its goals. We give an operational semantics for Orpheus and implement this semantics in an adapter to help build agents. We use the adapter to demonstrate how Orpheus simplifies the programming of decentralized multiagent systems compared to the reactive programming model. 

Current languages for specifying multiagent protocols either over-constrain protocol enactments or complicate capturing their meanings. We propose Langshaw, a declarative protocol language based on (1) sayso, a new construct that captures who has priority over setting each attribute, and (2) nono and nogo, two constructs to capture conflicts between actions. Langshaw combines flexibility with an information model to express meaning. We give a formal semantics for Langshaw, procedures for determining the safety and liveness of a protocol, and a method to generate a message-oriented protocol (embedding needed coordination) suitable for flexible asynchronous enactment. 

We model a multiagent system (MAS) in socio-technical terms, combining a social layer consisting of norms with a technical layer consisting of actions that the agents execute. We express stakeholder needs to ensure that a MAS demonstrates resilience, allowing it to recover effectively from failures within a brief timeframe. This extended abstract presents a framework that computes probabilistic and temporal guarantees on whether the underlying requirements are met or, if failed, recovered. An important contribution of the framework is that it shows how the social and technical layers can be modeled jointly to enable the construction of resilient systems of autonomous agents. This paper facilitates specification refinement through methodological guidelines, emphasizing joint modeling of social and technical layers. We demonstrate our framework using a manufacturing scenario with competing public, industrial, and environmental requirements. This is an extended abstract of our JAAMAS paper available online. 

We model a multiagent system (MAS) in socio-technical terms, combining a social layer consisting of norms with a technical layer consisting of actions that the agents execute. This approach emphasizes autonomy, and makes assumptions about both the social and technical layers explicit. Autonomy means that agents may violate norms. In our approach, agents are computational entities, with each representing a different stakeholder. We express stakeholder requirements of the form that a MAS is resilient in that it can recover (sufficiently) from a failure within a (sufficiently short) duration. We present ReNo, a framework that computes probabilistic and temporal guarantees on whether the underlying requirements are met or, if failed, recovered. ReNo supports the refinement of the specification of a socio-technical system through methodological guidelines to meet the stated requirements. An important contribution of ReNo is that it shows how the social and technical layers can be modeled jointly to enable the construction of resilient systems of autonomous agents. We demonstrate ReNo using a manufacturing scenario with competing public, industrial, and environmental requirements.