1. Chapter 6 - Modeling Eduardo Felipe Zecca da Cruz

2. Domain- and Style – Specific ADLs Some ADLs are domain-specific or style-specific, or at least optimized for describing architectures in a particular domain or style Importance Scope is better tailored to stakeholder needs Unnecessary details could be left because there is little need for genericity Comprises A reference architecture, which describes a general computational framework for a significant domain of applications; A component library, which contains reusable chunks of domain expertise; and An application configuration method for selecting and configuring components within the architecture to meet particular application requirements.

3. Koala Developed by Philips Electronics Specially designed for modeling embedded software for consumer electronics Inherits from Darwin Semantically and syntactically Uses Darwin’s structural concepts of input and output ports Expands them through the addition of constructs to support product-line architectures Multiple products can be described with a single model, with differences between the products encoded as variation points

4. Evaluation Rubric for Koala Scope and PurposeStructures and interfaces of product lines of component-based systems Basic ElementsComponents, interfaces, and constructs for variation points: diversify interfaces, switches, etc. StyleProduct lines might be seen as very narrow styles Static and Dynamic Aspects Static structure and interfaces Dynamic ModelingN/A Non-Functional Aspects N/A Ambiguity Concrete and closely mapped to implementations. Ambiguity is limited Accuracy Close mappings to implementations. It is easy to identify problems PrecisionConfiguration is well defined but other aspects are nor specified ViewpointsStructural viewpoint with explicit points of variation View ConsistencyN/A

5. Weaves Architectural style and accompanying notation. Used for modeling systems of small-grain tool fragments that process objects of data Advantages Extremely optimized notation Even simpler than Darwin diagrams Close mapping to implemented systems Disadvantages Addresses structure and data flows only

6. Lunar Lander Components do not communicate by request- response procedure call. They communicate by streams of objects Basic flows of data are similar to the other models Explicit presence of return channels for data A request that travels from a way does not imply that a response comes back along the same way The response way must be specified Information about structural connections but does not capture aspects of how those connections are used Could be included with an additional model like natural language

7. Evaluation Rubric for Weaves Scope and PurposeStructures and configuration of components in the Weave style Basic ElementsComponents, connectors (queues), and directed interconnections StyleWeaves style implicit Static and Dynamic Aspects Only static structure is modeled Dynamic Modeling N/A. Although there is a close correspondence between model and implementation components Non-Functional AspectsN/A AmbiguityWell defined and not ambiguous AccuracySyntactic errors are easy to identify PrecisionComponents and connectors are well defined, but other aspects are not specified ViewpointsStructural viewpoint View ConsistencyN/A

8. AADL It contains useful constructs and capabilities for modeling a wide variety of embedded and real-time systems such as automotive and medical systems. Can describe interfaces to components for both the flow of control and data Can capture non-functional aspects of components such as timing, safety, and reliability attributes

9. AADL Components Components are defined in two parts Component type Defines the interfaces to a component Component implementation An instance of a particular component type Component’s category (additional element that affects components) Can be hardware, software, or composite

10. More AADL Advantages Allows detailed specification of both hardware and software aspects of a system Automated analysis tools check interesting end-to-end properties of system Disadvantages Verbose; large amount of detail required to capture even simple systems

11. Lunar Lander Just one part is modeling The Calculation component and its connection to the Data Store component. The components are connected by a physical Ethernet bus Real-time version Activities are done at regular intervals

12. Evaluation Rubric for AADL Scope and PurposeMultilevel models of interconnected hardware and software elements Basic ElementsMyriad hardware and software elements: networks, buses, ports, etc. StyleN/A Static and Dynamic Aspects Primarily static aspects, but properties can capture some dynamic aspects Dynamic ModelingN/A Non-Functional Aspects N/A Ambiguity Much of elements have well-understood semantics. Properties add detail about behavior to reduce ambiguity AccuracyStructural and properties can be automatically analyzed PrecisionProperties specify characteristics of each element ViewpointsInterconnected hardware and software viewpoints View ConsistencyOSATE includes several plug-ins for various consistency checks

13. Extensible ADLs Can be used to combine the flexibility of generic languages with the analyzability and precision of semantically rich languages. Provide a basic set of constructs for describing certain common architectural concerns Include support Basic approach to employing an extensible ADL is as follows Determine which concerns can be modeled using the existing (baseline) capabilities of the ADL For those concerns that cannot be modeled using the baseline capabilities, choose how to extend the ADL to support their modeling (or reuse an extension developed by another user) Extend the ADL and its supporting tools as necessary to support the modeling of the unique features

14. ACME Has a base set of seven constructs Components Connectors Ports Roles Attachments Systems Representations Properties Decorations that can be applied to any of the basic seven kinds of elements

15. ACME Advantages Structural specification capabilities similar to Darwin Simple property structure allows for arbitrary decoration of existing elements Tool support with AcmeStudio Disadvantages No way to add new views Property specifications can become extremely complex and have entirely separate syntax/semantics of their own

16. Lunar Lander Largely structural and includes components, connectors, ports, roles and attachments Verbosity Use of properties Additional properties could be added using ACME to model Lunar Lander

17. Evaluation Rubric for ACME Scope and PurposeStructural aspects of a software architecture, with the extensible properties Basic ElementsComponents, connectors, ports and roles, attachments, representations and properties StyleThrough type system Static and Dynamic Aspects Static structure is modeled natively, dynamic aspects in properties Dynamic ModelingAcmeLib allows models to be manipulated programmatically Non-Functional AspectsThrough properties Ambiguity Elements are well defined, but external mean is not defined Properties need being accompanied by tools or documentation Otherwise ambiguity could be introduced AccuracyTyping can check elements and properties are checked by external tools PrecisionProperties can increase precision but is not possible to define new elements ViewpointsStructural viewpoint is native, properties can be used to provide additional viewpoints View ConsistencyVia external tools that must be developed

18. ADML XML-based architecture Syntax derived from ACME ADML is supported by meta-properties Advantages XML parsers and tools readily available Added some ability to reason about types of properties with meta-properties Disadvantages Properties are still name-value pairs Did not take advantage of XML extension mechanisms

19. Lunar Lander Similar to ACME Use of XML opens this specification up to a wider array of tools Verbose is denser than in ACME

20. xADL XML-based language An attempt to provide a platform upon which common modeling features can be reused from domain to domain and new features can be created and added to the language as first-class entities On the other languages they are added as extensions to other entities

21. xADL Advantages Growing set of generically useful modules available already Tool support in ArchStudio environment Users can add their own modules via well-defined extensibility mechanisms Disadvantages Extensibility mechanisms can be complex and increase learning curve Heavy reliance on tools

22. xADL Data Binding Library It is a software library that provides an API for parsing, reading, writing, and serializing documents in a particular language In xADL it is a set of Java classes that correspond to xADL data types Data Binding Library provides a simple interface to make these operations (read, write, query, manipulate)

23. Apigen It is a xADL’s data binding library generator Given a set of XML schemas, the Apigen can generate the complete data binding library with support for those schemas For any changes or adds, Apigen will generate a new data binding library by rerunning

24. Lunar Lander Similar to ADML and ACME Has an associated graphical visualization provided by an editor called Archipelago Application can be extended using new schemas and these schemas can be reused in another projects

25. Evaluation Rubric for xADL Scope and PurposeModeling different architectural concerns with support for extensibility Basic Elements Components, connectors, interfaces, links, options, variants, versions, plus any basic elements defined in extensions StyleThrough the use of types and type libraries Static and Dynamic Aspects Static structure is modeled natively, dynamic properties can be captured through extensions. Dynamic ModelingxADL data binding library allows models to be manipulated programmatically Non-Functional AspectsThrough extensions Ambiguity Base schemas are permissive Extensions add rigor or formality if needed Accuracy Tools check the correctness of xADL documents Users can add additional constraints into these tools to handle extensions PrecisionBase schemas are abstract; Extensions can be used to add precision Viewpoints Structural viewpoints are natively supported Extensions can be used to provide additional viewpoints View ConsistencyExternal tools can check the consistency

26. When Systems Become too Complex to Model Certain applications cannot be modeled using the techniques that were used on the Lunar Lander example Gigantic and diverse applications like the Web or Gnutella Impossible to generate a model of these systems in the traditional components-connectors-and-configuration sense There are some strategies to consider to model these systems

27. Strategies Model Limited Aspects of the Architecture Use Cases Interaction Patterns More limited and easier to be modeled Model an Instance Consider if a complete model is needed Modeling only the relevant portion of the system

28. Strategies Exploit Regularity Large systems have low heterogeneity These large portions can be modeled once and repeated automatically Model the Style Instead of modeling as an application, consider modeling the REST style instead WEB is based on the REST architecture Model the Protocol Model protocol details HTTP example on the Web

29. References Taylor, R. N., & Medvidovic, N. (2010).Software architecture: foundations, theory, and practice. Hoboken, N.J.: Wiley. Taylor, R. N., & Medvidovic, N. (2010).Software architecture: foundations, theory, and practice. Hoboken, N.J.: Wiley. Modeling and Notations - http://www.softwarearchitecturebook.com/svn/main/slides/ppt/10_Model ing_and_Notations.ppt http://www.softwarearchitecturebook.com/svn/main/slides/ppt/10_Model ing_and_Notations.ppt Domain-Specific Software Architecture and Product Lines – http://www.csse.usc.edu/classes/cs578_2013/DSSE.ppt http://www.csse.usc.edu/classes/cs578_2013/DSSE.ppt