Annerose Braune

Evaluation of OPC UA secure communication in web browser applications

OPC UA XML Web services mapping offers a Web service interface to access process data. Web services use XML technology for data exchange. Present-day Web browsers include XML functionality already as a standard feature, they are therefore very promising candidates for the implementation of monitoring and operating functions for industrial processes. However, the acceptance of Web services in industrial automation depends on adequate security realizations. For this purpose, the Web services security stack provides several specifications to meet the requirements for secure message exchange. The OPC UA XML Web services mapping refers to these specifications. The application of Web browsers for monitoring and operating of technical processes using OPC UA Web services demand the computation of cryptographic algorithms within the scripting engine of the Web browser. However, available scripting languages are not designed to compute complex mathematical, i.e., cryptographic, algorithms. Therefore, at the Institute of Automation of the Technische Universitat Dresden the suitability of a native Web browser for monitoring and operating of industrial processes with OPC UA based secure communication was analyzed. The paper shows representative measured computing times of cryptographic algorithms in JavaScript. The security specification XML signature - which is mandatory for OPC UA Web services mapping - requires about 700 ms to create a signature. Finally, the paper discusses methods to improve the performance.

Towards context adaptive HMIs in process industries

This paper presents the combination of two distinct model driven HMI engineering approaches. Together they setup a complete toolchain that lays the basis for the model driven (semi)automatic generation of flexible, multi-platform HMIs for process industries. The two approaches are autoHMI which derives a concrete UI design from Computer Aided Engineering Data, and XVCML which allows to generate final UIs for different web implementation paradigms like XHTML or Java on top of OPC UA. This tool integration provides a complete model driven software engineering architecture that cuts down the manual efforts in HMI engineering close to zero. This is a prerequisite to handle the complexity of context adaptive interfaces.

Sustainable visualization solutions in industrial automation with Movisa — A case study

Current visualization systems in industrial automation mostly rely on dedicated runtime environments making the migration of visualization solutions from one platform to another almost impossible. On the other hand, an increasing number of different platforms has to be used also in industrial automation, to monitor or to operate the technical process. We propose with Movisa a model-driven approach to the development of sustainable visualization solutions in industrial automation. Movisa is a Domain Specific Language designed to capture only functional contents of visualization solutions. This paper presents Movisa by introducing its main concepts in a case study. It will also point out the potential of model-driven approaches concerning the sustainability of visualization solution in industrial automation.

A generic transformation algorithm to simplify the development of mapping models

Declarative mapping models aim at simplifying the development of model transformations by separating (1) the configuration of mappings between elements of the source and target meta-model and (2) the execution of these mappings. Existing solutions however require an extended definition of the mappings that, e.g., also describes how generated elements need to be connected. In this paper, we propose a generic transformation algorithm that is able to execute mappings that do not specify such extended information by analyzing the structure of the target meta-model. This limits the effort necessary for the definition of mappings and ensures a valid target model already at early stages of development. After analyzing the tasks that model transformations needs to perform, we present our approach towards generic transformation rules for models that are based on the Eclipse Modeling Framework and illustrate a concrete implementation by means of an integration into our own model transformation framework.

User driven evolution of user interface models - The FLEPR approach

In model-based user interface development, models at different levels of abstraction are used. While ideas may initially only be expressed in more abstract models, modifications and improvements according to users feedback will likely be made at the concrete level, which may lead to model inconsistencies that need to be fixed in every iteration. Transformations form the bridge between these models. Because one-to-one mappings between models cannot always be defined, these transformations are completely manual or they require manual post-treatment. We propose interactive but automatic transformations to address the mapping problem while still allowing designers creativity. To manage consistency and semantic correctness within and between models and therefore to foster iterative development processes, we are combining these with techniques to track decisions and modifications and techniques of intra- and inter-model validation. Our approach has been implemented for abstract and concrete user interface models using Eclipse-based frameworks for model-driven engineering. Our approach and tool support is illustrated by a case study.

Using Executable UML to model algorithmic aspects of visualization systems

The XML based modeling language of graphical user interfaces for visualization systems in automation, XVCML, has been developed to ensure the consistency of visualization solutions in the fast-moving field of consumer technology. Until now, it only provides modeling elements for visualization of real time process data and the necessary communication relationships with data servers. In order to be accepted in practice, XVCML also needs modeling components for additional, user defined algorithms. This paper presents an approach to enhance XVCML with generic, algorithmic components to perform e.g. simple algebraic operations. For this purpose, Executable UML has been used and proven to be suitable. Therefore, Executable UML will be introduced and first experiences will be shown by an early prototype which realizes a typical scenario of industrial automation.

Towards a model driven approach for development of visualization applications in industrial automation

The eXtensible Visualization Components Markup Language (XVCML) was developed in order to ensure the sustainability of visualization solutions. Therefore, XVCML follows the Model-Driven Software Development (MDSD) approach: It enables technology independent modeling of visualization solutions whereas those models are compliant to a formal metamodel. XVCML was enhanced by a mean to express arbitrary routines using Executable UML. Since we realized the latter aspect only as a first proof of concept, this part of XVCML lacks a formal metamodel—a requirement for MDSD. This paper seizes on this topic so much that a Domain Specific Language, which enables the creation of Executable UML models, will be worked out in the context of MDSD. Therefore, this paper explains the required foundations for the subject matter at hand before it presents the way of proceeding towards a model-driven approach with XVCML.

Integrated design of Human-Machine Interfaces for production plants

During the development of production plants, powerful tools (e.g. for CAD, CAE, or simulation) are used. The resulting engineering data represent the basis for the development of the corresponding HMI. However, this development is usually still performed manually to a great extent. Therefore, this paper describes a model-based approach for the integrated design of HMIs for production plants. Beginning with the aggregation of available engineering data in a plant model, a multi-step transformation workflow is presented. The user is enabled to edit the intermediary results and thus influence the generated HMI. A concrete implementation of the workflow is presented by means of a case study for a sample production plant.

Platform Constraints Supporting an Ambiguous Mapping Model

Abstract Model transformations constitute the linking element between the different layers of abstraction in Model-Based User Interface Development (MBUID). They map source elements onto target elements and define rules for the execution of these mappings. While the execution of the transformation requires unambiguous mappings, ambiguous mappings are very common in MBUID (e.g. an abstract “selection” element could be mapped either to a drop-down list or to a set of radio buttons). These ambiguities have to be resolved during the design process considering the target platform characteristics among others. The definition and evaluation of such constraints is usually performed informally by the designer when selecting the unambiguous mappings. The target platform properties are thus only integrated implicitly into the transformation, i.e. the transformation has to be reprogrammed for every change of the platform characteristics. This paper therefore presents a proposal for a conditional ambiguous mapping model that allows the explicit definition of platform constraints based on platform models. Furthermore, all possible (ambiguous) mappings for a pair of source and target user interface description languages can be described so that the platform constraints can be attached to them. This allows the automatic selection of (unambiguous) mappings suitable for the target platform during the execution of the transformation. Consequently, a single transformation can support a variety of platforms. A case study shows the applicability of the approach.

Multi-platform user interface models by means of the Abstract Platform concept

Model-based user interface development methods offer capabilities to cope with the increasing effort needed for the development of industrial visualization systems. This increasing effort emerges among others from new device classes like smart phones or tablets to be supported. Current modeling languages usually support a dedicated class of platforms, e.g. either PCs or smart phones. Thus, despite of comparable functionality of the user interface, the support of different platforms requires a manual redevelopment of the solution or dedicated transformations towards a modeling language with another platform focus. This paper discusses the introduction of abstract platform models to support multiple platform classes in a single user interface model. In detail, we present an approach for the abstraction of input capabilities of panel PCs and tablets. Furthermore, the effects on the transformation generating the final user interfaces as well as restrictions and benefits of our approach are discussed.