Upload
hewitt
View
59
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Applied Architectures and Styles. Chapter 11, Part 2. Service-Oriented Architectures and Web Services Architectures from Specific Domains Robotics Wireless Sensor Networks. Service-Oriented Architectures and Web Services. Supports business enterprises on the internet - PowerPoint PPT Presentation
Citation preview
Applied Architectures and StylesChapter 11, Part 2
• Service-Oriented Architectures and Web Services
• Architectures from Specific Domains• Robotics• Wireless Sensor Networks
Service-Oriented Architectures and Web Services
Supports business enterprises on the internet
Independence is fundamental
Conceptually part of the decentralized design space
Significant complexity
Service-Oriented Architectures and Web Services
Independent Components Interface describing what operations they provide Have their own thread of control Can be described using WSDL
Web Services Description Language XML
APIs written in languages such as Java, PHP, Ruby
Service-Oriented Architectures and Web Services
Connectors of SOA Asynchronous Event Notification
Sends structured XML document to service provider Variety of protocols: HTML, Email, etc. No obligation for provider to return anything to
requestor
Different from remote procedure calls No object persistence Absence of programming semantics
Service-Oriented Architectures and Web Services
Requires Architecture Description Language Formality and complete semantics required Similar to a scripting language
Other Architectural Styles and Concepts Publish/Subscribe Mechanisms for discover of new
services or service providers
Service-Oriented Architectures and Web Services
Significant Complexity Interoperability across platforms Open, decentralized system Difficult to change services once announced
Compares to Java and changing a public method
Due to these issues, developers often choose REST instead of SOAP REST – focuses on the exchange of representations/data SOAP – focuses on the invocations of functions with
arguments Amazon provides both methods
Service-Oriented Architectures and Web Services
Architectures from Specific Domains
Robotics Sense-Plan-Act Subsumption Three-Layer Reuse-Oriented
Wireless Sensor Networks
Architectures from Specific Domains
Robotics Examples Mobile tele-operated systems
Full or partial control of the robot’s systems is handled by a human operator
Industrial automation systems Autonomous Environment conforms to robot
Mobile autonomous robots Autonomous Navigate varying environments
Architectures from Specific Domains
Robotics Challenges Physical platforms and devices Unpredictable nature of the environment
Robotic Software Qualities Robustness Performance Reusability Adaptability
Architectures from Specific Domains
Sense-Plan-Act (SPA) Unidirectional Sense – Interface with the world Plan – Behavior
Reconciles actual state with internal model Internal model repeatedly updated in response to
newly acquired sensor information Objective it to keep the model consistent with actual
environmental conditions
Architectures from Specific Domains
Sense-Plan-Act (SPA) – Drawbacks Sensor information must be integrated (known as
sensor-fusion) and incorporated into planning models at each step
These operations are very time consuming and typically cannot keep up with environmental changes
Therefore this model does not scale well as robot capabilities and goals expand
Architectures from Specific Domains
Subsumption Inhibition and Suppression No world model or plan Independent components, each encapsulating specific behavior or
skill Reactive in nature Excellent performance
Drawbacks Lack of coherent architectural plan Components inserted into data flow depending on task without
position necessarily being related to the layer with in which they are located
Three-Layer Architecture (3L) Hybrid of SPA and Subsumption Three Layers
Reactive Sequencing Planning
Challenges Deciding how to separate functionality into layers Reconciliation of world and behavior models
Architectures from Specific Domains
Architectures from Specific Domains
Reuse-Oriented Component Reuse Object Oriented Middleware Frameworks
Few Frameworks Player (http://playerstage.sourceforge.net) Orca (http://orca-robotics.sourceforge.net) Microsoft Robots Studio (http://msdn.microsoft.com/robotics) Lego Mindstorms (http://www.mindstorms.lego.com)
Architectures from Specific Domains
Wireless Sensor Networks (WSN) Sensor nets Monitor the environment Widely used
Medical systems Navigation Industrial automation
Low installation costs Easy reconfiguration
Architectures from Specific Domains
WSN Challenges Integration with legacy systems, other embedded devices,
mobile networks PDAs, cell phones, etc.
Typical Constraints Power Bandwidth Range Processing capacity Falt-tolerance Availability Scalability
Architectures from Specific Domains
Bosch Research and Technology Center and University of Southern California Three separate architectural styles to achieve all
goals Peer-to-peer Publish-subscribe Service-oriented