Components und Connectors

Transkript

1 Components und Connectors Components runtime processors and data stores. implemented with a combination of custom, reusable, and COTS Connectors mechanisms that allow for the exchange of data between components. implemented using COTS, technologies, and protocols. format of the data that is exchanged may be custom or standard. Martin Jud NDS-I SWE III 1 Adapted from Systems Design by David L. March, DeSales University Webpage C&C View: Architectural Styles Pipe and Filter Shared Data Subscriber subscribe events Publisher Publish-Subscribe Client request service Server Client-Server A B services Peer-to-Peer C D Martin Jud NDS-I SWE III 2 Aus der Vorlesung Achritektur von Jörg Hofstetter HTA Luzern

2 Stile der C&C View Pipe-and-Filter Component: Filter Connector: Pipe Data Transformation Shared Data Component: Repositories Connector: Data Reader/Writer Multiple Accessors & Persistence Publish-Subscribe Component: any Connector: publish-subscribe Send events & msgs. to unknown set of recipients Client-Server Component: Client und Server Connector: request/reply Decoupling Apps. from Services Peer-to-Peer Component: Peer Connector: bidirectional RPC Collaboration Communicating Processes Component: any concurrent unit Connector: data exchg., msg. passing, sync., ctrl. Concurrent Systems Martin Jud NDS-I SWE III 3 Adapted from Documenting SW Architectures by Paul Clements et. al. Addison Wesley Component vs. Module Component : A non-trivial, nearly independent, and replaceable part of a system that fulfills a clear function in the context of a well-defined architecture. A Component can be installed and/or instantiated -> has a runtime presence. A component conforms to and provides the physical realization of a set of interfaces. There is a Component Specification and Implementation. Module: A software unit of storage and manipulation. Implements a set of responsibilites Martin Jud NDS-I SWE III 4 Aus der Vorlesung Achritektur von Jörg Hofstetter HTA Luzern

3 Module View -> Structure Logical / Conceptual Structure: The units are abstractions of the systems functional requirements -> Analysis-model Decomposition: focusing on is-part-of relation Layer: virtual machines with interfaces Uses structure: focus on depends-on Main «use» Split ToLower ToUpper Merge Config Stdio Capitalize System Martin Jud NDS-I SWE III 5 Aus der Vorlesung Architektur von Jörg Hofstetter HTA Luzern Component & Connector View -> Behavior Components & Connector: Execution Units + Shared Data Data flow: Data flow between components. Control flow: Becomes active after Process: What components run in parallel? Deployment: Mapping of components to hardware ToLower «dataflow» Split Merge ToUpper Martin Jud NDS-I SWE III 6 Aus der Vorlesung Architektur von Jörg Hofstetter HTA Luzern

4 Component Specification Export: A list of supported interfaces, which other components may use. Import: A list of used foreign Interfaces. Export A Import C B Body: The behaviour of the component, relationships between the interfaces. Martin Jud NDS-I SWE III 7 Aus der Vorlesung Architektur von Jörg Hofstetter HTA Luzern Component Qualities To use a component you just need to know the Export-Interfaces. Two Components with the same Export-Interfaces are replacable. A Component is testable without knowledge about the body (Black-box test). You can develop components independably. Components are important for reuse. Martin Jud NDS-I SWE III 8 Aus der Vorlesung Architektur von Jörg Hofstetter HTA Luzern

5 Connectors - Issues Issues that must be addressed to establish and successfully use a connection: Control Flow Which component initiates (opens) the connection? Which component terminates (closes) the connection? Can the connection be terminated before the exchange is complete? What control protocol is used to exchange the data? Data Flow What is the format of the data? Does the data flow in one direction or both directions? Transmission Media What media (paper, voice, electrical) is used to transport the data? Does the connection need to transform the data from one media type to another? Martin Jud NDS-I SWE III 9 Adapted from Systems Design by David L. March, DeSales University Webpage Connection Styles If the consumer of the data initiates the connection, the consumer pulls the data from the producer. The producer must be prepared to accept the connection at a time of the consumer's choosing. If the producer of the data initiates the connection, the producer pushes the data to the consumer. The consumer must be prepared to accept the connection at a time of the producer's choosing. Martin Jud NDS-I SWE III 10 Adapted from Systems Design by David L. March, DeSales University Webpage

6 Pull / Push Example The sender is a producer that opens a connection to push the message to the receiver. The difficulty with pushing to the receiver is that the receiver may not be available to accept the connection. The architecture that is used to convert from a push connection to a push-pull connection is shown on the left. Martin Jud NDS-I SWE III 11 Adapted from Systems Design by David L. March, DeSales University Webpage UML 2.0 Component (Basic Concept) ist ein Subtype von Class, Class Component -> Komponente hat Attribute, Operationen und kann an Assoziationen und Generalisierungen teilnehmen. Muss eine Realisierung haben -> ist damit ein ausführbares Element in einem System. definiert sein Verhalten über zur Verfügung gestellte und benötigte Interfaces. stellt ein ersetzbares Element dar, das zur Design- oder Laufzeit durch eine Komponente mit den selben Interfaces ersetzt werden kann. Hat eine external view ( black-box view ) und eine internal view ( white-box view ). Martin Jud NDS-I SWE III 12

7 UML 2.0: Component Notation Bestell Material Bestelleingang Alternative Darstellung: Bestell Material Bestelleingang Martin Jud NDS-I SWE III 13 UML 2.0: Component White Box view Port Part Martin Jud NDS-I SWE III 14

8 UML 2.0: Ports Auto Connector Hinten :Rad [2] a Achse Port a e:motor Antriebs- Welle Interaktionspunkte eines Classifiers Classifier kommuniziert mit Aussenwelt via Ports Ports können Typ haben, nur Module mit Port s des selben Typs können zusammengesteckt werden Typ Martin Jud NDS-I SWE III 15 UML 2.0: Interface Assembly connector: Ball Filesystem WriteLine Provided Interface Socket LogLine WriteLine Logger Requested Interface Alternative Darstellungsart: Filesystem WriteLine WriteLine Logger Martin Jud NDS-I SWE III 16

9 UML 2.0: Port & Interface Bestellt Prozess OnlineService BestellEingang Bezahlung Port kann Interfaces (provided + requested) beinhalten! Interface - Eine Deklaration öffentlicher Features - Nicht direkt instanzierbar, wird durch die Instanz eines anderes Classifiers realisiert. Port - Interaktionspunkt zwischen Classifier - Instanzieren eines Classifiers erzeugt auch die Instanzen der zugehörigen Ports. - Ist ein Port durch Interfaces typisiert - gibt es einen instanzierbaren Classifier, der diese Interfaces realisiert. - ist das Interaktions-Objekt eine Instanz dieses Classifiers und kann Verhalten haben -> z.b: Datenfilterung. Martin Jud NDS-I SWE III 17 C&C View: Process structure in UML 2.0 Object Diagram Class Diagram A B «process» Klasse A Active Object D Active Object: Concurrent Task, Process, Thread «thread» Klasse B Martin Jud NDS-I SWE III 18

10 C&C View: Process structure in UML, II aproducertask aconsumertask Message from Thread b 1a: send( in message) 1b: receive( out message) amessagequeue send()/receive():critical section! IF Queue is full, send() blocks until there is place in the queue). IF Queue is empty, receive() blocks until there is new data in the queue. MessageQueue - Queue + send() {concurrent} +receive() {concurrent} Martin Jud NDS-I SWE III 19 Aus der Vorlesung Achritektur von Jörg Hofstetter HTA Luzern Connector Technology Manual Connectors used when both components are allocated to different manual processors. Mail / Phone / Fax Manual/Automated Connectors used when one of the components is allocated to a manual processor and the other component is allocated to an automated processor. Keyboard / Display Automated Connectors used when both components are allocated to the same or different automated processors. Automated connectors are implemented using middleware to handle format conversions and control flow. Procedure Call Temporary File HTTP / SOAP / RMI / IIOP / FTP Martin Jud NDS-I SWE III 20 Adapted from Systems Design by David L. March, DeSales University Webpage

11 Automation Boundary a general architecture for an enterprise application involves three types of events: Automated Event triggered by a stimulus that crosses the system boundary into the automated partition by means of an automated connector. Manual Event triggered by a stimulus that crosses the system boundary into the manual partition by means of a manual connector. Operator Event triggered by a stimulus that crosses the boundary between the manual and automated partitions by means of an operator connector. An operator connector must convert the data from manual media to electronic form. Martin Jud NDS-I SWE III 21 Adapted from Systems Design by David L. March, DeSales University Webpage Subsystems System Subsystem A Subsystem B Subsystem A-1 Subsystem A-2 Subsystem B-1 «Realisation» Component a Component b Component c Component d Martin Jud NDS-I SWE III 22 Aus der Vorlesung Achritektur von Jörg Hofstetter HTA Luzern

12 An example of Subsystems Electrical System Lamp A Battery Car Motor Lamp B.. Steering Gear Unit Wheels Martin Jud NDS-I SWE III 23 Aus der Vorlesung Achritektur von Jörg Hofstetter HTA Luzern Top-Down / Bottom-Up Top-Down System Bottom-Up A B Sub- Systeme A-1 A-2 B-1 Martin Jud NDS-I SWE III 24 Aus der Vorlesung Achritektur von Jörg Hofstetter HTA Luzern