Towards a formal model for composable container systems

Abstract

In modern cloud-based architectures, containers play a central role: they provide powerful isolation mechanisms such that developers can focus on the logic and dependencies of applications while system administrators can focus on deployment and management issue. In this work, we propose a formal model for container-based systems, using the framework of Bigraphical Reactive Systems (BRSs). We first introduce local directed bigraphs, a graph-based formalism which allows us to deal with localized resources. Then, we define a signature for modelling containers and provide some examples of bigraphs modelling containers. These graphs can be analysed and manipulated using techniques from graph theory: properties about containers can be formalized as properties of the corresponding bigraphic representations. Moreover, it turns out that the composition of containers as performed by e.g. docker-compose, corresponds precisely to the composition of the corresponding bigraphs inside an "environment bigraph" which in turn is obtained directly from the YAML file used to define the composition of containers.

Towards improving architectural diagram consistency using system descriptors

“…Up to our knowledge, this is the first work that proposes an approach to improving architectural diagrams consistency using system descriptors. Related studies are from Paraiso et al [18] and Burco et al [19].…”

Computing Embeddings of Directed Bigraphs

“…Edges of the first sub-network are described by the variables in (3) and their capacity is bounded by the number of points linked by the host handle since this is the maximum acceptable flux and corresponds to the case where each point passes through the same hyperedge of the guest link graph. Edges of the second sub-network are described by the variables in (5) and, like the first group of links, have their capacity limited to 1; to be precise, some of these variables will never assume a value different from 0 because guest points can receive flux from anything but the host ports (as expressed by constraint (11)). Edges for the link structure of the guest are presented implicitly in the flux preservation constraints (see constraint (9)).…”

“…The dynamics of a system is defined by means of a set of graph rewriting rules, which can replace and change components' positions and connections. BRSs have been successfully applied to the formalization of a wide spectrum of domain-specific models, including context-aware systems, web-service orchestration languages [4,5,20,28]. BRSs are appealing because they provide a range of general results and tools, which can be readily instantiated with the specific model under scrutiny: libraries for bigraph manipulation (e.g., DBtk [1] and jLibBig [23,24]), simulation tools [10,19,21], graphical editors [9], model checkers [27], modular composition [26], stochastic extensions [18], etc.…”

“…such as those found in client-server or producer-consumer scenarios. In fact, they have been used to design formal models of security protocols [12], molecular biology [2], access control [15], container-based systems [5], etc.…”

“…More precisely, in Sect. 2 we first introduce directed bigraphs and bigraphic reactive systems, generalizing [5,13]. Then, the notion of directed bigraph embedding is defined in Sect.…”