Analysis and Design of Software Architecture Essay

Outline1 2 3 4 5 6 7 8Development Process Requirements t maven of voice Attri andes Run while QA Non-run m QA Requirements psychoanalysis physical exercise architectural abstract & vitamin A heading architectural ViewsDenis Helic (KMI, TU Graz)SA depth psychology and markOct 19, 20112 / 78Development Processmethodological analysisDierent softwargon using processes have softw atomic number 18 package architecture as a part of the process Rational unied process Spiral developing method Agile knowledge method Evolutionary rapid developmentDenis Helic (KMI, TU Graz)SA outline and architectural planOct 19, 20113 / 78Development Process stead of SA in SDPFigure Source Softw ar Architecture f enforcee by Reekie, McAdam Denis Helic (KMI, TU Graz) SA epitome and flesh Oct 19, 2011 4 / 78Development Processmethodological analysisAfter the initial requirements analysis but before softw argon contrive The rst architecture is also a communication basis with the customer Inputs fo r the development of the architecture 1 2Requirements Context (technical, organizational, business, )Denis Helic (KMI, TU Graz)SA epitome and fleshOct 19, 20115 / 78Requirements abstractAt the beginning there is of all time a customer who wants a specic softw be schema of rules Customer wishes are al vogues informal Interviews, some documents, some Excel tables, We have to give out much(prenominal) informal records and body structure it Requirements applied science is a huge long time but we just illustrate here one possibilityDenis Helic (KMI, TU Graz)SA synopsis and creationOct 19, 20116 / 78Requirements outlineThe results of the requirements analysis1 2 running(a) requirements Non-functional requirements(a) Runtime qualities (b) Non-runtime qualities3contextual requirementsDenis Helic (KMI, TU Graz)SA abridgment and goalOct 19, 20117 / 78Requirements operable requirementsA technical expression of what a organisation provideing do Arise from stakeholder needfully coordinated language software requirements specication intent cases structured description of substance ab exploiter interactions with the placement Formal theoretical accounts e.g. state-chartsDenis Helic (KMI, TU Graz)SA outline and jut outOct 19, 20118 / 78RequirementsNon-functional requirementsOther take than directly functional or business- link Generally expressed in the form of quality-attributes Runtime quality attributes Non-runtime quality attributesDenis Helic (KMI, TU Graz)SA digest and initiationOct 19, 20119 / 78RequirementsContextual requirementsWhat technology is available? expertise of the development team Previous experience of users/customers Technical, business, market, legal, ethical, Denis Helic (KMI, TU Graz)SA psychoanalysis and objectOct 19, 201110 / 78Quality AttributesNeed to address QAsWithout all need for accomplishment, scalability, any implementation of functionality is acceptable However, we always need to take into account the broader mise en scene E.g. hardware, technological, organizational, business, The functionality must(prenominal) be there but without proper addressing of QA it is worth zipDenis Helic (KMI, TU Graz)SA outline and introductionOct 19, 201111 / 78Quality AttributesInuence on QAsTypically, a mavin cistron flush toilet non address a QA completely Any QA is inuenced by quintuple regions and their interactions E.g. a UI component has a high degree of usability however, usability of the form is compromised if a entropy commission component has poor work in accessing the data users need to detainment long poor usability Components and their interactions software architecture QAs are directly inuenced by software architectureDenis Helic (KMI, TU Graz)SA compendium and traffic patternOct 19, 201112 / 78Runtime QAPURSPURS ( surgery, usability, reliability, security) surgical process time writ of doing, memory, disk, or web utilization Usability human factors, lucky to lea rn, easy to use, reliability availability, safety, guarantor au thuslytication, data protection, Denis Helic (KMI, TU Graz)SA abridgment and somaOct 19, 201113 / 78Runtime QA doingTime act is most obvious calculated in the number of operations per foster Also, latency the time from receiving an input and producing an output Other footsteps memory, disk, net profit utilization or throughputDenis Helic (KMI, TU Graz)SA abbreviation and somaOct 19, 201114 / 78Runtime QA actDierent measures are typically traded o against to each one separate E.g. increasing throughput may increase latency Time effectance aptitude be increased with more memory True performance of the ashes is non and dened by performance of single components that also by their interactions and the overall processes in the agreementDenis Helic (KMI, TU Graz)SA outline and human bodyOct 19, 201115 / 78Runtime QA functioning factorsChoice of algorithms Database design Communication option manageme ntDenis Helic (KMI, TU Graz)SA analysis and targetOct 19, 201116 / 78Runtime QAChoice of algorithmsPerformance of algorithms is measured by their complexness (big O) E.g. linear complexity O(n) Running time increases in direct proportion to the size of the data E.g. polynomial complexity O(n2 ) It does not scale double size of the data running time increased by factor of 4 Goal O(nlog (n))Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201117 / 78Runtime QADatabase designPerformance of database queries poop dominate the overall performance The design of the tables has enormous collision on the overall performance Techniques to improve it lazy evaluation, retort, caching Some additional cost to manage replication and/or caching In-memory databases (real-time constitutions) Developing a new database (search engines)Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201118 / 78Runtime QACommunicationNetwork overhead Package data correspond to a protocol, sending da ta over communicate severally socio-economic class means additional overhead Think how to use communicate packaging binary data as XML? Use more compact formats, e.g. JSON vs XMLDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201119 / 78Runtime QAResources managementOverloaded components need to be avoided A chain is only as strong as its weakest association E.g. a single-threaded shared resource is in use all other threads are blocked Very dicult to vestige pigDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201120 / 78Runtime QAUsabilityUsability is a very overflowing eld If usability is es directial you will need a usability expert combination of many factors responsiveness, writtenal design, user expectations, condence Measuring with time taken to complete task, error rate, time to solution, Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201121 / 78Runtime QAResponsiveness and data availabilityAn ex adeninele of relations between QAs Usabil ity requires that the scheme responds to user actions within a certain period of time If it is a complex organisation this need translates into performance along the path of the user actionDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201122 / 78Runtime QAResponsiveness and data availabilityFigure Usability vs. Performance Source Software Architecture Primer by Reekie, McAdamDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201123 / 78Runtime QA tidings on relations between QAsThis plat shows that we need to afford attention to adjust communicationbetween B and Y Performance of the communication deal is a consequence of a usability requirement Do we need to stake security of the communication channel?Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201124 / 78Runtime QADiscussion on relations between QAsThis diagram shows that we need to pay attention to tuning communication between B and Y Performance of the communication channel is a consequence of a u sability requirement Do we need to get security of the communication channel? We swan QAs always only as a solvent to user necessitate neer because it is postulate anywayDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201124 / 78Runtime QADiscussion on relations between QAsIf we nutrition security even if it is not needed Very practically QAs exerciseopposing forces on the clay pledge requires a lot of checking performance will suer usability will suer A minimalistic approach develop only what is requiredDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201125 / 78Runtime QAReliabilityIn traditional engineering disciplines reliability measures the failure rate of the musical arrangement Failure rate specied by mean time to failure MTTF A related measure mean time between failures MTBF MTTR is mean time to repair A is availabilityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201126 / 78Runtime QAReliabilityMTBF = MTTF + MTTR A= A=MTTF MTBF MTTF MTT F +MTTRE.g. expected availability of meshing dustsDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201127 / 78Runtime QAReliabilityMTBF = MTTF + MTTR A= A=MTTF MTBF MTTF MTTF +MTTRE.g. expected availability of weathervane systems 1 (always up-and-running) = MTTF Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201127 / 78Runtime QAReliabilityincrease reliability involves dischargeing However, impossible to prove that a system is correct, i.e. without bugs acceptability of errors depends on the nature of a system Personal desktop use bugs are typically tolerated Enterprise direct medium reliability level High-reliable systems bugs bay window be fatalDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201128 / 78Runtime QASecurityIncreasingly important aspect of systems is security Because systems are unfastened to threats Especially networked systems As with other QAs security is a set of related responses to user needsDenis Helic (KMI, TU Graz)SA Analy sis and DesignOct 19, 201129 / 78Runtime QA credentialsRequirement for identication of users with a system Users present credentials so that the system give the bounce identify them Typically username and password Other forms certicates, smart cards, biometric featuresDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201130 / 78Runtime QAAuthorizationAfter authentication license which functions and what data is available for users This information is captured in an authorization model vex have lists (ACL) dene who house access and how a resource might be accessed E.g. read access, write access, delete access, Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201131 / 78Runtime QAAuthorizationDrawbacks of ACLs It is resource based, e.g. a page in a CMS Often, authorization needs to address functions or tasks Also, managing of ACLs is dicult, e.g. subresources of resources Also, performance problems with checkingDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201132 / 78Runtime QAAuthorizationAnother model role-based access control (RBAC) Roles are utilize to manage many-to-many relations between users and permissions Roles are used to represent the job functions, e.g. author, teacher, student in an E-learning system Permissions are copy as parts of roles, e.g. create page, create tests, Users are than assigned to a role and acquire automatically permissions of that roleDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201133 / 78Non-runtime QA metricsMeTRiCS (maintainability, evolvability, testability, reusability, integrability, congurability, scalability) Maintainability how easy burn you x bugs and add new features Evolvability how easy your system copes with limitings Testability how easy can you test the system for correctnessDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201134 / 78Non-runtime QAMeTRiCSReusability how easy is to use software elements in other contexts, e.g. a software library Integrability how easy you can make the separately developed components of the system work correctly together Congurability how easy can a system be congured for dierent installations and target groups Scalability how easy the system copes with a higher performance demandDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201135 / 78Non-runtime QAMaintainabilityThis QA considers the whole lifecycle of a system What happens during system operation? Property that allows a system to be modied after(prenominal) deployment wirh ease E.g. extensible, modied demeanour, xing errorsDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201136 / 78Non-runtime QAMaintainabilityAt the design and implementation level Code comments Object-oriented principles and design rules Consistent programming styles DocumentationDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201137 / 78Non-runtime QAMaintainabilityMaintainability is very important because any software system will change over time Experience sh ows that such changes consort to degrade the system over time Software systems are subject area to entropy The cumulative eect of changes degrades the quality of the systemDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201138 / 78Non-runtime QAMaintainabilityThe systems tend to become messy systems disregarding of how a nice plan you had at beginning Design for change recollect OO design rules Abstract messy parts of the system so that they can be exchangedDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201139 / 78Non-runtime QAMaintainability take int be afraid to refactor and rewrite and redesign Each software vendor does this with major versions Create throw-away prototypes Think out-of-box and innovate Dont always follow a hype very often nothing new in hypes E.g. Web servicesDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201140 / 78Non-runtime QATestabilityMeans to improve testability Test cases if something fails there is a bug Separation of the testing framework and the system, i.e. testing with scripts from outside put downDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201141 / 78Non-runtime QACongurabilityAbility of a system to vary its operational parameters without re-compiling or re-installing E.g. selecting appropriate database drivers, conguring network parameters, Typically, realized by a set of conguration les E.g. Apache Web emcee conguration le sets host name, virtual hosts, Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201142 / 78Non-runtime QACongurabilityCongurability interacts with other QAs such as testability, maintainability, reliability High degree of congurability tends to have a negative impact on those QAs Testing of dierent system conguration becomes more dicult reliability compromised Congurable components will be strongly parametrized decreased maintainabilityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201143 / 78Non-runtime QAScalabilityAbility of a system to in crease its efficiency without re-compiling or re-installing E.g. serving additional Web pages means only copy these Web pages into a Web server le system some time increasing capacity means increasing hardware, e.g. Web server clusters Managing user session on the client side, means only providing additional mandate-on-demand from the serverDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201144 / 78Requirements Analysis representative ashes descriptionWeb-based Network Analysis animate being W-NAT A simple and uncommitted system for network analysis is needed. Networks are entities that contain not only individuals but also their connections with other individuals (see e.g. 3 for an example). The system accepts a network representations as a list of pairs of connected nodes stored in a dataset le. Nodes are represented as integers. An edge between two nodes is stored as a line containing two nodes delimited by a tabulator. Users might upload datasets to the systems and s tore them for further analysis. Each user might upload eight-fold datasets and can execute various analysis on those datasets. The system keeps the track of the analysis write up for each user. Users may calculate degree distributions, network diameter, clustering coecient, connectivity measures, droll values, and dierent centrality measures. Denis Helic (KMI, TU Graz) SA Analysis and Design Oct 19, 2011 45 / 78Requirements Analysis moralSystem descriptionWeb-based Network Analysis Tool W-NAT Users can execute various deliberations on triplex datasets in parallel. The system must not be blocked if a weighing is currently down the stairs way. Rather it should be possible to start a new deliberateness, or view previous calculations, and so forth In case of longer calculations the system needs to notify the user by e-mail when the calculation is over. The results of the calculations should be available in textual and in graphical form. every results can be also transfered t o a local computer. The system will be used by a group of students that learn the basics of network analysis. It is expect that at any times the system will be used by multiple users executing multiple calculations. Since the system is earlier an educational tool it needs to be pedagogically sound, i.e. simplicity and usability are very important.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201146 / 78Requirements Analysis fontSystem description6 How to search in a smooth worldPajekFigure 2 HP Labs email communication (light grayness lines) mapped onto the organizational hierarchy of HP Labs constructed out the e-mail communication. Figure loving network(black lines). Note that communication tends to cling to of formal organizational chart. From How to search a social network, Adamic, 2005.with one another. The h-distance, used to navigate the network, is computed as follows individuals have h-distance one to their manager and to everyone they share a manager with. D istances are then recursively assigned, so that each individual has h-distance 2 to their rst neighbors neighbors, and h-distance 3 to their second Denis Helic (KMI, TU neighbors neighbors, etc. SA Analysis and Design Graz)Oct 19, 201147 / 78Requirements Analysis role modelSystem descriptionWeb-based Network Analysis Tool W-NAT The system is a Web-based system and the users should be able to operate the system by using a standard Web browser. The users need not install any additional plugins to operate the system. User perceived performance of the system should be acceptable. In addition, standard Web usability concepts need to be followed. In particular, browser back button must be working(a) at all times and it should be possible to bookmark pages at all times. Finally, standard Web design principles should be satised, meaning that pages are valid (X)HTML pages in at least HTML Transitional. The system needs to support cross browser compatibility. Further, each page and each imp ortant application state needs to have a unique and human-readable URL.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201148 / 78Requirements Analysis moral operable requirementsUR1 The system is a network analysis tool. The system can calculate the hobby measures. UR1.1 UR1.2 UR1.3 UR1.4 UR1.5 Out-degree distribution In-degree distribution Cumulative out-degree distribution Cumulative in-degree distribution vamoose plotDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201149 / 78Requirements Analysis characterFunctional requirementsUR1 The system is a network analysis tool. The system can calculate the following measures. UR1.6 Clustering coecient UR1.7 statistical distribution of weakly connected components UR1.8 Distribution of strongly connected components UR1.9 Left singular vector UR1.10 Right singular vectorDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201150 / 78Requirements Analysis illustrationFunctional requirementsUR1 The system is a network analysis tool. The system can calculate the following measures. UR1.12 UR1.12 UR1.13 UR1.14 UR1.15 Network singular values Degree centrality beastliness centrality Betweenness centrality Eigenvector centralityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201151 / 78Requirements Analysis causeFunctional requirementsUR2 Networks are stored in dataset les. UR3 The dataset le has the following format. NodeID1 t NodeID2n UR4 Users can upload multiple datasets to the system. UR5 To perform an analysis users select a dataset and then choose a measure to calculate.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201152 / 78Requirements Analysis pillowcaseFunctional requirementsUR6 For each user and for each dataset the system manages a history of calculations. UR7 Users may initiate multiple calculations simultaneously. UR8 When a calculation is started the system is not blocked. UR9 The system noties users about a nished calculation by e-mail.Denis Helic (KMI, TU Graz) SA Analysis and DesignOct 19, 201153 / 78Requirements Analysis ExampleFunctional requirementsUR6 For each user and for each dataset the system manages a history of calculations. UR7 Users may initiate multiple calculations simultaneously. UR8 When a calculation is started the system is not blocked. UR9 The system noties users about a nished calculation by e-mail. When is this notication needed? If the user is logged out?Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201153 / 78Requirements Analysis ExampleFunctional requirementsUR10 The calculation results are presented in a textual as nearly as in a graphic form.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201154 / 78Requirements Analysis ExampleFunctional requirementsUR10 The calculation results are presented in a textual as healthful as in a graphic form. Which form? Format? artistic production format?Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201154 / 78Requirements Analysis ExampleFunctional requirementsUR10 The calculation results are presented in a textual as well as in a graphic form. Which form? Format? artwork format? UR11 Users can transfer the calculation results.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201154 / 78Requirements Analysis ExampleFunctional requirementsUR10 The calculation results are presented in a textual as well as in agraphic form. Which form? Format? Graphics format? UR11 Users can download the calculation results. Single results? All results? Archived, how archived?Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201154 / 78Requirements Analysis ExampleFunctional requirementsUR10 The calculation results are presented in a textual as well as in a graphic form. Which form? Format? Graphics format? UR11 Users can download the calculation results. Single results? All results? Archived, how archived? UR12 Users can register with the system.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201154 / 78Requirements Analysi s ExampleFunctional requirementsUR10 The calculation results are presented in a textual as well as in a graphic form. Which form? Format? Graphics format? UR11 Users can download the calculation results. Single results? All results? Archived, howarchived? UR12 Users can register with the system. How register? netmail? Captcha?Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201154 / 78Requirements Analysis ExampleFunctional requirementsUR10 The calculation results are presented in a textual as well as in a graphic form. Which form? Format? Graphics format? UR11 Users can download the calculation results. Single results? All results? Archived, how archived? UR12 Users can register with the system. How register? E-mail? Captcha? UR13 Users can login and log out.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201154 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and pedagogically sound.Denis Helic (KMI, TU Graz)SA Analysis a nd DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and pedagogically sound. UsabilityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and didactically sound. Usability UR2 The system needs to support multiple users simultaneously.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and didactically sound. Usability UR2 The system needs to support multiple users simultaneously. PerformanceDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and didactically sound. Usability UR2 The system needs to support multiple users simultaneously. Performance How many users?Denis Helic (KMI, TU Graz)SA Analysis and DesignO ct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and didactically sound. Usability UR2 The system needs to support multiple users simultaneously. Performance How many users? UR3 corroboration should be supported.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and didactically sound. Usability UR2 The system needs to support multiple users simultaneously. Performance How many users? UR3 certification should be supported. SecurityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and didactically sound. Usability UR2 The system needs to support multiple users simultaneously. Performance How many users? UR3 corroboration should be supported. Security UR4 User-perceived performance must be acceptableDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and didactically sound. Usability UR2 The system needs to support multiple users simultaneously. Performance How many users? UR3 Authentication should be supported. Security UR4 User-perceived performance must be acceptable Performance and UsabilityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and didactically sound. Usability UR2 The system needs to support multiple users simultaneously. Performance How many users? UR3 Authentication should be supported. Security UR4 User-perceived performance must be acceptable Performance and Usability How many seconds at max users can wait?Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and didac tically sound. Usability UR2 The system needs to support multiple users simultaneously. Performance How many users? UR3 Authentication should be supported. Security UR4 User-perceived performance must be acceptable Performance and Usability How many seconds at max users can wait? UR5 Web-based system should be available at all times.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR1 The system is simple, usable and didactically sound. Usability UR2 The system needs to support multiple users simultaneously. Performance How many users? UR3 Authentication should be supported. Security UR4 User-perceived performance must be acceptable Performance and Usability How many seconds at max users can wait? UR5 Web-based system should be available at all times. ReliabilityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201155 / 78Requirements Analysis ExampleNon-functional requirementsUR6 Human-readable URLs.Den is Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201156 / 78Requirements Analysis ExampleNon-functional requirementsUR6 Human-readable URLs. Evolvability, reusability, maintainability, testability, integrabilityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201156 / 78Requirements Analysis ExampleNon-functional requirementsUR6 Human-readable URLs. Evolvability, reusability, maintainability, testability, integrability UR7 Extending the system with new metrics.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201156 / 78Requirements Analysis ExampleNon-functional requirementsUR6 Human-readable URLs. Evolvability, reusability, maintainability, testability, integrability UR7 Extending the system with new metrics. Evolvability, reusability, maintainability, testability, integrability, congurabilityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201156 / 78Requirements Analysis ExampleNon-functional requirementsUR6 Human-readable URLs. Evolvability, reusability, maintainability, testability, integrability UR7 Extending the system with new metrics. Evolvability, reusability, maintainability, testability, integrability,congurability UR8 Reliability of a Web-based system.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201156 / 78Requirements Analysis ExampleNon-functional requirementsUR6 Human-readable URLs. Evolvability, reusability, maintainability, testability, integrability UR7 Extending the system with new metrics. Evolvability, reusability, maintainability, testability, integrability, congurability UR8 Reliability of a Web-based system. TestabilityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201156 / 78Requirements Analysis ExampleNon-functional requirementsUR6 Human-readable URLs. Evolvability, reusability, maintainability, testability, integrability UR7 Extending the system with new metrics. Evolvability, reusability, maintainability, testability, integrability, congurability UR8 Reliability of a Web-based system. T estability UR9 twofold users.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201156 / 78Requirements Analysis ExampleNon-functional requirementsUR6 Human-readable URLs. Evolvability, reusability, maintainability, testability, integrability UR7 Extending the system with new metrics. Evolvability, reusability, maintainability, testability, integrability, congurability UR8 Reliability of a Web-based system. Testability UR9 Multiple users. ScalabilityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201156 / 78Requirements Analysis ExampleContextual requirementsUR1 Web browser. UR2 Valid (X)HTML, at least (X)HTML Transitional. UR3 No browser plugins are allowed.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201157 / 78architectural Analysis & DesignAnalysisWe analyze the requirements and probe to identify so-called refer concepts Understanding of the domain Static part of the domain We also try to identify key process and activities Dynamic part of the domain Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201158 / 78architectural Analysis & DesignDesignDesign is the process of creating models (recollect the denition of SA) Two basic types of architectural models Structure and style architectural structure is a static model of a system (i.e. how the system is divided into components) architectural behavior is a ever-changing model of a system (i.e. how the components interact with each other to perform some useful work)Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201159 / 78architectural Analysis & Designarchitectural structureThe division of a system into components and connectors To represent the model box-and-lines diagrams (to see at a inspect important concepts) It is important to remember that diagrams are only representations of the model Diagrams must always be accompanied by additional somatic such as text, data models, mathematical models, etc. The combination of diagrams and additional secular is an architectural modelDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201160 / 78architectural Analysis & Designarchitectural structureWhat is a component? What is a connector? Components might be subsystems, separate processes, source code packages, Connectors might be network protocols, method invocations, associations, The combination of diagrams and additional material is an architectural modelDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201161 / 78architectural Analysis & Designarchitectural structureFigure Example of an architectural structureDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201162 / 78Architectural Analysis & DesignArchitectural structureIn the diagram we have one user-interface and one database component But what is the criteria for deciding what is a component? Separate program modules? Separate threads or processes? abstract or functional division? And what about connectors? Network protocols? Callbacks? Request/respons e cycles? Method invocations?Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201163 / 78Architectural Analysis & DesignArchitectural structureWhat is the level of nubbiness of a diagram? E.g. for a Web-based system, components are servers and browsers and connector is HTTP But, components of a server are HTTP parser, le I/O, cache, plug-ins, Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201164 / 78Architectural Analysis & DesignArchitectural structureComparison with OO a component is an object and a connector is a message sent between two objects Because models in OO are very well dened on that pointfore, we need additional information that accompanies diagrams To describe criteria for decomposition and provide explanations on granularityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201165 / 78Architectural Analysis & DesignArchitectural behaviorComplementing structure is architectural behavior interaction of system elements to perform some us eful work Functionality vs. behavior Functionality is what the system can do and behavior is the activity sequenceDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201166 / 78Architectural Analysis & DesignArchitectural behaviorExample Accessing a tweets document Request is sent to the Web presentation layer That layer forwards the request to the application logic, e.g. TweetDeck TweetDeck contacts TweetViews to father a particular template, then retrieves the data from TweetDB wraps it into an HTML response and sends the response to TweetUI Functionality allows me to display a tweets document, behavior is the sequence of activities that makes it happenDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201167 / 78Architectural Analysis & DesignArchitectural behaviorEach component has a set of responsibilities Behavior is the way how these responsibilities are exercised to respond to some event An event may be an action of the user or an event from an external syste m A particular behavior is an event plus a response in the form of a sequence of component responsibilitiesDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201168 / 78Architectural Analysis & DesignArchitectural behaviorTo represent behavioral models we use use-case map notation by Buhr A use-case map consists of a watch over drawn through a geomorphologic diagram of the system The path of the touch sensation through a structural diagram shows the sequence of activities Each crossing of a component by the trace indicates exercising of a responsibilityDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201169 / 78Architectural Analysis & DesignArchitectural behaviorFigure Types of traces in use-case mapsDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201170 / 78Architectural Analysis & DesignArchitectural behavior(a) Single trace all responsibilities exercised sequentially (b) Two traces are consecutive Equivalent to single trace but shows that continu ation is triggered by another event (c) And-Fork The traces after the line are potentially concurrent (run in parallel)Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201171 / 78Architectural Analysis & DesignArchitectural behaviorFigure Types of traces in use-case mapsDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201172 / 78Architectural Analysis & DesignArchitectural behavior(a) N-Way And-Fork the trace after the fork may be replicated an arbitrary number of times (b) Or-Fork The trace is split and activity proceeds along one or another path (c) Seq-Fork The traces after the line are followed in the dress indicated by the arrowDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201173 / 78Architectural Analysis & DesignArchitectural behaviorFigure Example of architectural behaviorDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201174 / 78Architectural ViewsArchitectural viewsWe can examine a system from dierent points of view Dierent kinds o f views conceptual components are set of responsibilities and connectors are ow of information Execution components are execution units (processes) and connectors are messages between processes Implementation components are libraries, source code, les, etc and connectors are protocols, api calls, etc.Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201175 / 78Architectural ViewsArchitectural viewsThere are other models as well We will mention them but we will investigate only previous three models Data model describes the data Physical modeldescribes servers, rewalls, workstations, Denis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201176 / 78Architectural ViewsArchitectural viewsEach view provides dierent information about the structure of the system Each view addresses a specic set of concerns All views taken together is the primary means of documenting software architectureDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201177 / 78Architectural ViewsArchitectu ral viewsThe conceptual architecture considers the structure of the system in terms of its domain-level functionality The execution architecture considers the system in terms of its runtime structure The implementation architecture considers the system in terms of its build-time structureDenis Helic (KMI, TU Graz)SA Analysis and DesignOct 19, 201178 / 78