Declarative Elasticity in ABS

Abstract

Traditional development methodologies that separate software design from application deployment have been replaced by approaches such as continuous delivery or DevOps, according to which deployment issues should be taken into account already at the early stages of development. This calls for the definition of new modeling and specification languages. In this paper we show how deployment can be added as a first-class citizen in the object-oriented modeling language ABS. We follow a declarative approach: programmers specify deployment constraints and a solver synthesizes ABS classes exposing methods like deploy (resp. undeploy) that executes (resp. cancels) configuration actions changing the current deployment towards a new one satisfying the programmer's desiderata. Differently from previous works, this novel approach allows for the specification of incremental modifications, thus supporting the declarative modeling of elastic applications.

Analysis of SLA Compliance in the Cloud - An Automated, Model-based Approach

“…A solver computes which new resources are required and how new service instances should be distributed on these resources, or how old objects and resources that are no longer necessary should be un-deployed, given the knowledge of the current resource configuration and the new requirements indicated by the monitoring framework. Fully automatic dynamic elasticity can be obtained thanks to the combined use of the monitoring framework and the external deployment solver [14].…”

Human-in-the-Loop Simulation of Cloud Services

“…This suite integrates the SAGA tool [3] for the declarative specification of service metric functions, and SmartDeployer [6] for the formalization of deployment requirements and the automatic generation of provisioning scripts. At the core of this suite is a new Haskell backend ABS RT of the ABS modeling language which supports a real-time interpretation of the timing constructs of ABS.…”

“…We further illustrate the use of our tool-suite by an industrial case study based on the Fredhopper Cloud Services. The underlying ABS model of the Fredhopper Cloud Services builds on the one presented in [6] which focuses on automated generation of deployment actions. Here we extend that model to support HITL simulation and for the generation of more realistic deployment recommendations.…”

“…-The SAGA tool [3] was tweaked for monitoring SLA metrics and the Grafana framework visualizes the metrics -The SmartDeployer [6] for synthesizing deployment actions -A logreplay tool for replaying real-world log files -The new Haskell ABS RT backend for real-time simulations (Sect. 2).…”

“…Our tool suite further integrates SmartDeployer [6] for the formalization of deployment requirements, and the automatical derivation of an executable (in ABS) provisioning script that synthesizes a deployment satisfying all specified requirements. By further integrating SmartDeployer actions into the executable, SLA-level monitors generated by SAGA, we have a formalized model that automatically suggests appropriate scaling actions at the right time: when the values of the SLA metrics give rise to it.…”