Architecture-Driven Programming for Sense/Compute/Control Applications
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Software architectures have long been used to design the structure of a software and to impose constraints on the software implementation. Existing approaches are capable of formally verifying properties on these constraints at the design stage. However, few approaches verify that a given implementation conforms to the software architecture constraints, and even fewer use these constraints to guide developers during implementation. In this presentation, we propose a generative approach to enforce the software architecture constraints during implementation. Toward this goal, we focus on a specific application area, Sense/Compute/Control applications, which are applications that interact with a physical or virtual environment. Our work is based on a domain-specific architectural pattern dedicated to SCC applications. The data-flow of this pattern is restricted by interaction constraints. For specifying such constraints, we propose a dedicated language of behavioral contracts, adapted to our architectural pattern. These behavioral contracts are used for automatically generating a dedicated programming framework. This framework enforces the conformance of the resulting implementation with the software architecture constraints and provides guidance to developers.
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Architecture-Driven Programming for Sense/Compute/Control Applications
- 1. Architecture-Driven Programming for Sense/Compute/Control Applications Damien Cassou, Émilie Balland, Charles Consel, Julia Lawall 1
- 2. 1.Design • facilitates communication • documents decisions • guides development 2
- 3. 1.Design • facilitates communication • documents decisions Architecture Description Languages • guides development (ADLs) 2
- 4. 2.Implement based on the design as a contemplative document General Purpose Languages (GPLs) 3
- 5. 3.Check conformance 4
- 11. 3.Check conformance • costly • slow • error-prone manual operation 4
- 12. Our Approach 5
- 13. 3.Check conformance • costly • slow • error-prone manual operation 6
- 14. 3.Check conformance • costly • slow • error-prone compiler produces a dedicated programming framework 6
- 15. 3.Check conformance • costly • free • slow • immediate • error-prone • error-free compiler produces a dedicated programming framework 6
- 16. compiler 7
- 17. compiler builds a programming framework which • guides the implementation • provides high-level support • ensures conformance 7
- 18. compiler dedicated to the application builds a programming framework which • guides the implementation • provides high-level support • ensures conformance 7
- 19. compiler dedicated to the application builds a programming framework which • guides the implementation • provides high-level support • ensures conformance heavily rely on the Java type checker 7
- 20. Our Approach an ADL + generation of a dedicated programming framework 8
- 21. Our Approach a domain-specific ADL + generation of a dedicated programming framework 8
- 22. The Domain Sense/Compute/Control applications (SCC) 9
- 23. The Domain Sense/Compute/Control applications (SCC) “applications that interact with an environment” 9
- 24. The Domain Sense/Compute/Control applications (SCC) “applications that interact with an environment” 10
- 25. The Domain Sense/Compute/Control applications (SCC) “applications that interact with an environment” Cover various areas • building automation • application monitoring environment • robotics • autonomic computing • ... 10
- 26. The Domain Sense/Compute/Control applications (SCC) environment 11
- 27. The Domain Sense/Compute/Control applications (SCC) environment sensors 11
- 28. The Domain Sense/Compute/Control applications (SCC) environment sensors Sense 11
- 29. The Domain Sense/Compute/Control applications (SCC) environment context operators raw data sensors Sense 11
- 30. The Domain Sense/Compute/Control applications (SCC) environment context operators Compute raw data sensors Sense 11
- 31. The Domain Sense/Compute/Control applications (SCC) control operators context environment data context operators Compute raw data sensors Sense 11
- 32. The Domain Sense/Compute/Control applications (SCC) orders actuators control operators context environment data context operators Compute raw data sensors Sense 11
- 33. The Domain Sense/Compute/Control applications (SCC) orders actuators control operators context environment data context operators Compute raw data sensors Sense 11
- 34. The Domain Sense/Compute/Control applications (SCC) Control orders actuators control operators context environment data context operators Compute raw data sensors Sense 11
- 35. The Domain orders actuators control operators context data context operators raw data sensors 12
- 36. The Domain actuators orders control operators context data context operators raw data sensors 12
- 37. The Domain actuators control operators context operators 12 sensors
- 38. Web Server Monitoring actuators control operators context operators 13 sensors
- 39. Web Server Monitoring actuators control operators environment = the web server context operators 13 sensors
- 40. Web Server Monitoring actuators control operators context operators 13 sensors
- 41. Web Server Monitoring actuators control IntrusionInformer operators context operators 13 sensors
- 42. Web Server Monitoring Mailer actuators control IntrusionInformer operators context operators 13 sensors
- 43. Web Server Monitoring Mailer actuators control IntrusionInformer ProfileLogger operators context operators 13 sensors
- 44. Web Server Monitoring Mailer Logger actuators control IntrusionInformer ProfileLogger operators context operators 13 sensors
- 45. Web Server Monitoring Mailer Logger actuators control IntrusionInformer ProfileLogger operators context Accessing Profile operators 13 sensors
- 46. Web Server Monitoring Mailer Logger actuators control IntrusionInformer ProfileLogger operators context Accessing Profile operators 13 sensors
- 47. Web Server Monitoring Mailer Logger actuators control IntrusionInformer ProfileLogger operators Intrusion Detector context Accessing Profile operators 13 sensors
- 48. Web Server Monitoring Mailer Logger actuators control IntrusionInformer ProfileLogger operators Intrusion Detector context Accessing Profile operators AccessLog Parser 13 sensors
- 49. Web Server Monitoring Mailer Logger actuators control IntrusionInformer ProfileLogger operators Intrusion Detector context Accessing Profile operators AccessLog Parser AccessLogReader 13 sensors
- 50. Web Server Monitoring Mailer Logger actuators control IntrusionInformer ProfileLogger operators Intrusion Detector context Accessing Profile operators AccessLog IP2Profile Parser AccessLogReader 13 sensors
- 51. Web Server Monitoring Mailer Logger actuators control IntrusionInformer ProfileLogger operators Intrusion Detector context Accessing Profile operators AccessLog IP2Profile Parser AccessLogReader NSLookup 13 sensors
- 52. Web Server Monitoring Mailer Logger actuators control IntrusionInformer ProfileLogger operators Intrusion Detector context Accessing Profile operators AccessLog IP2Profile Parser AccessLogReader NSLookup 13 LDAP sensors
- 53. Web Server Monitoring Mailer Logger actuators email(...) log(AccessInfo,Profile) control IntrusionInformer ProfileLogger operators AccessInfo Intrusion Detector (AccessInfo,Profile) context Accessing Profile Profile operators AccessInfo [IPAddress] AccessLog IP2Profile Parser String Profile String [IPAddress] [String] AccessLogReader NSLookup 13 LDAP sensors
- 54. context Accessing Profile operators AccessLog IP2Profile Parser 14 sensors
- 55. what the architect expresses context Accessing Profile operators AccessLog IP2Profile Parser 14 sensors
- 56. what the architect would like to express context Accessing Profile operators AccessLog IP2Profile Parser 14 sensors
- 57. what the architect would like to express context Accessing Profile operators AccessLog IP2Profile Parser 14 sensors
- 58. what the architect would like to express context Accessing Profile operators AccessLog IP2Profile Parser 14 sensors
- 59. what the architect would like to express activation condition context Accessing Profile operators AccessLog IP2Profile Parser 14 sensors
- 60. what the architect would like to express data context Accessing requirement Profile operators AccessLog IP2Profile Parser 14 sensors
- 61. what the architect would like to express emission context Accessing Profile operators AccessLog IP2Profile Parser 14 sensors
- 62. Behavioral Contracts context Accessing Profile operators AccessLog IP2Profile Parser 15 sensors
- 63. Behavioral Contracts ⟨ ; ; ⟩ context Accessing Profile operators AccessLog IP2Profile Parser 15 sensors
- 64. Behavioral Contracts activation condition ⟨⇑AccessLogParser ; ; ⟩ context Accessing Profile operators AccessLog IP2Profile Parser 15 sensors
- 65. Behavioral Contracts activation data condition requirement ⟨⇑AccessLogParser ; ⇓IP2Profile ; ⟩ context Accessing Profile operators AccessLog IP2Profile Parser 15 sensors
- 66. Behavioral Contracts activation data emission condition requirement ⟨⇑AccessLogParser ; ⇓IP2Profile ; ⇑self⟩ context Accessing Profile operators AccessLog IP2Profile Parser 15 sensors
- 67. Behavioral Contracts context operators IP2Profile NSLookup 16 LDAP sensors
- 68. Behavioral Contracts ⟨ ; ; ⟩ context operators IP2Profile NSLookup 16 LDAP sensors
- 69. Behavioral Contracts activation condition ⟨⇓self ; ; ⟩ context operators IP2Profile NSLookup 16 LDAP sensors
- 70. Behavioral Contracts activation data condition requirement ⟨⇓self ; (⇓NSLookup, ⇓LDAP) ; ⟩ context operators IP2Profile NSLookup 16 LDAP sensors
- 71. Behavioral Contracts activation data emission condition requirement ⟨⇓self ; (⇓NSLookup, ⇓LDAP) ; ∅⟩ context operators IP2Profile NSLookup 16 LDAP sensors
- 72. Web Server Monitoring Mailer Logger actuators control IntrusionInformer ProfileLogger operators Intrusion Detector context Accessing Profile operators AccessLog IP2Profile Parser AccessLogReader NSLookup 17 LDAP sensors
- 73. Mailer Logger actuators 3.Check conformance control IntrusionInformer ProfileLogger operators Intrusion Detector context Accessing Profile operators AccessLog IP2Profile Parser AccessLogReader NSLookup LDAP sensors compiler produces a dedicated programming framework 18
- 74. Programming Framework Mailer Logger IntrusionInformer ProfileLogger Intrusion Detector Accessing Profile AccessLog IP2Profile Parser AccessLogReader NSLookup LDAP 19
- 75. Programming Framework Mailer Logger IntrusionInformer ProfileLogger Intrusion For each component: Detector • an abstract class Accessing Profile AccessLog IP2Profile Parser AccessLogReader NSLookup LDAP 19
- 76. Programming Framework Mailer Logger For each component: IntrusionInformer ProfileLogger • an abstract class Intrusion For each interaction: Detector • an abstract method Accessing Profile AccessLog IP2Profile Parser AccessLogReader NSLookup LDAP 19
- 77. Programming Framework For each component: • an abstract class Mailer Logger For each interaction: IntrusionInformer ProfileLogger • an abstract method Intrusion Dedicated support: Detector • interfaces Accessing • proxies Profile • composites AccessLog Parser IP2Profile • discovery • RPC AccessLogReader NSLookup LDAP • ... 19
- 78. Accessing Profile AccessLog IP2Profile Parser 20
- 79. (AccessInfo,Profile) architecture Accessing Profile AccessInfo Profile [IPAddress] AccessLog ⟨ ; ; ⟩ IP2Profile Parser abstract class AccessingProfile { abstract Pair<AccessInfo,Profile> onNewAccessLogParser(AccessInfo newAccess, IP2ProfileClosure ip2Pro); } framework 20
- 80. (AccessInfo,Profile) architecture Accessing Profile AccessInfo Profile [IPAddress] AccessLog ⟨⇑AccessLogParser ; ; ⟩ IP2Profile Parser abstract class AccessingProfile { abstract Pair<AccessInfo,Profile> onNewAccessLogParser(AccessInfo newAccess, IP2ProfileClosure ip2Pro); } framework 20
- 81. (AccessInfo,Profile) architecture Accessing Profile AccessInfo Profile [IPAddress] AccessLog ⟨⇑AccessLogParser ; ⇓IP2Profile ; ⟩ IP2Profile Parser abstract class AccessingProfile { abstract Pair<AccessInfo,Profile> onNewAccessLogParser(AccessInfo newAccess, IP2ProfileClosure ip2Pro); } framework 20
- 82. (AccessInfo,Profile) architecture Accessing Profile AccessInfo Profile [IPAddress] AccessLog ⟨⇑AccessLogParser ; ⇓IP2Profile ; ⇑self⟩ IP2Profile Parser abstract class AccessingProfile { abstract Pair<AccessInfo,Profile> onNewAccessLogParser(AccessInfo newAccess, IP2ProfileClosure ip2Pro); } framework 20
- 83. (AccessInfo,Profile) architecture Accessing Profile AccessInfo Profile [IPAddress] AccessLog ⟨ ; ; ⟩ IP2Profile Parser abstract class AccessingProfile { abstract onNewAccessLogParser(...);} framework class StdAccessingProfile extends AccessingProfile { @Override Pair<AccessInfo,Profile> onNewAccessLogParser(AccessInfo newAccess, IP2ProfileClosure ip2Pro){ Profile profile = ip2Pro.get(newAccess.getHost_ip()); return new Pair<AccessInfo,Profile>(newAccess, profile); } user code 21
- 84. (AccessInfo,Profile) architecture Accessing Profile AccessInfo Profile [IPAddress] AccessLog ⟨⇑AccessLogParser ; ⟨ ; ⟩ IP2Profile Parser abstract class AccessingProfile { abstract onNewAccessLogParser(...);} framework class StdAccessingProfile extends AccessingProfile { @Override Pair<AccessInfo,Profile> onNewAccessLogParser(AccessInfo newAccess, IP2ProfileClosure ip2Pro){ Profile profile = ip2Pro.get(newAccess.getHost_ip()); return new Pair<AccessInfo,Profile>(newAccess, profile); } user code 21
- 85. (AccessInfo,Profile) architecture Accessing Profile AccessInfo Profile [IPAddress] AccessLog ⟨⇑AccessLogParser ; ⇓IP2Profile ; ⟩ IP2Profile Parser abstract class AccessingProfile { abstract onNewAccessLogParser(...);} framework class StdAccessingProfile extends AccessingProfile { @Override Pair<AccessInfo,Profile> onNewAccessLogParser(AccessInfo newAccess, IP2ProfileClosure ip2Pro){ Profile profile = ip2Pro.get(newAccess.getHost_ip()); return new Pair<AccessInfo,Profile>(newAccess, profile); } user code 21
- 86. (AccessInfo,Profile) architecture Accessing Profile AccessInfo Profile [IPAddress] AccessLog ⟨⇑AccessLogParser ; ⇓IP2Profile ; ⇑self⟩ IP2Profile Parser abstract class AccessingProfile { abstract onNewAccessLogParser(...);} framework class StdAccessingProfile extends AccessingProfile { @Override Pair<AccessInfo,Profile> onNewAccessLogParser(AccessInfo newAccess, IP2ProfileClosure ip2Pro){ Profile profile = ip2Pro.get(newAccess.getHost_ip()); return new Pair<AccessInfo,Profile>(newAccess, profile); } user code 21
- 87. (AccessInfo,Profile) architecture Accessing Profile AccessInfo Profile [IPAddress] AccessLog ⟨⇑AccessLogParser ; ⇓IP2Profile ; ⇑self⟩ IP2Profile Parser only ways to interact! abstract class AccessingProfile { abstract onNewAccessLogParser(...);} framework class StdAccessingProfile extends AccessingProfile { @Override Pair<AccessInfo,Profile> onNewAccessLogParser(AccessInfo newAccess, IP2ProfileClosure ip2Pro){ Profile profile = ip2Pro.get(newAccess.getHost_ip()); return new Pair<AccessInfo,Profile>(newAccess, profile); } user code 21
- 88. Profile [IPAddress] architecture IP2Profile String Profile ⟨ ; ; ⟩ [IPAddress] [String] NSLookup LDAP abstract class IP2Profile { abstract Profile get(IPAddress paramIPAddress, NSLookupClosure nsLookup, LDAPClosure ldap); } framework 22
- 89. Profile [IPAddress] architecture IP2Profile String Profile ⟨⇓self ; ; ⟩ [IPAddress] [String] NSLookup LDAP abstract class IP2Profile { abstract Profile get(IPAddress paramIPAddress, NSLookupClosure nsLookup, LDAPClosure ldap); } framework 22
- 90. Profile [IPAddress] architecture IP2Profile String Profile ⟨⇓self ; (⇓NSLookup, ⇓LDAP) ; ⟩ [IPAddress] [String] NSLookup LDAP abstract class IP2Profile { abstract Profile get(IPAddress paramIPAddress, NSLookupClosure nsLookup, LDAPClosure ldap); } framework 22
- 91. Profile [IPAddress] architecture IP2Profile String Profile ⟨⇓self ; (⇓NSLookup, ⇓LDAP) ; ∅⟩ [IPAddress] [String] NSLookup LDAP abstract class IP2Profile { abstract Profile get(IPAddress paramIPAddress, NSLookupClosure nsLookup, LDAPClosure ldap); } framework 22
- 92. Profile [IPAddress] architecture IP2Profile String Profile ⟨ ; ; ⟩ [IPAddress] [String] NSLookup LDAP abstract class IP2Profile { abstract Profile get(...); } framework class StdIP2Profile extends IP2Profile { @Override Profile get(IPAddress paramIPAddress, NSLookupClosure nsLookup, LDAPClosure ldap){ String host = nsLookup.get(paramIPAddress); return ldap.pull(host); } user code } 23
- 93. Profile [IPAddress] architecture IP2Profile String Profile ⟨⇓self ; ; ⟩ [IPAddress] [String] NSLookup LDAP abstract class IP2Profile { abstract Profile get(...); } framework class StdIP2Profile extends IP2Profile { @Override Profile get(IPAddress paramIPAddress, NSLookupClosure nsLookup, LDAPClosure ldap){ String host = nsLookup.get(paramIPAddress); return ldap.pull(host); } user code } 23
- 94. Profile [IPAddress] architecture IP2Profile String Profile ⟨⇓self ; (⇓NSLookup, ⇓LDAP) ; ⟩ [IPAddress] [String] NSLookup LDAP abstract class IP2Profile { abstract Profile get(...); } framework class StdIP2Profile extends IP2Profile { @Override Profile get(IPAddress paramIPAddress, NSLookupClosure nsLookup, LDAPClosure ldap){ String host = nsLookup.get(paramIPAddress); return ldap.pull(host); } user code } 23
- 95. Profile [IPAddress] architecture IP2Profile String Profile ⟨⇓self ; (⇓NSLookup, ⇓LDAP) ; ⟩ [IPAddress] [String] NSLookup LDAP abstract class IP2Profile { abstract Profile get(...); } framework class StdIP2Profile extends IP2Profile { @Override Profile get(IPAddress paramIPAddress, NSLookupClosure nsLookup, LDAPClosure ldap){ String host = nsLookup.get(paramIPAddress); return ldap.pull(host); } user code } 23
- 96. Profile [IPAddress] architecture IP2Profile String Profile ⟨⇓self ; (⇓NSLookup, ⇓LDAP) ; ∅⟩ [IPAddress] [String] NSLookup LDAP abstract class IP2Profile { abstract Profile get(...); } framework class StdIP2Profile extends IP2Profile { @Override Profile get(IPAddress paramIPAddress, NSLookupClosure nsLookup, LDAPClosure ldap){ String host = nsLookup.get(paramIPAddress); return ldap.pull(host); } user code } 23
- 97. Unpresented Contributions • splash/oopsla 2010 • Formalization of the model • Analysis on the architecture • Architecture refinement • Coordination of data (synchronization / disjunction) 24
- 98. A suite of tools 25
- 99. DiaSpec a DSL to describe SCC applications device AccessLogReader extends StoppableDevice { source line as String; } context AccessLogParser as Access { source line from AccessLogReader; } context AccessingProfile as IdentifiedAccess { context AccessLogParser; context IP2Profile; } context IP2Profile as Profile indexed by ip as IPAddress { source ip2host from NSLookup; source host2profile from LDAPServer; } controller ProfileLogger { context AccessingProfile; action Log on Logger; } [GPCE’09] 26
- 100. A suite of tools device AccessLogReader extends StoppableDevice { source line as String; } a DSL to describe SCC applications context AccessLogParser as Access { source line from AccessLogReader; } context AccessingProfile as IdentifiedAccess { context AccessLogParser; context IP2Profile; } context IP2Profile as Profile indexed by ip as IPAddress { [GPCE’09] source ip2host from NSLookup; source host2profile from LDAPServer; } controller ProfileLogger { context AccessingProfile; action Log on Logger; } 27
- 101. DiaSim a simulator with 2D rendering [Mobiquitous’09] + [Demo at PERCOM’09] 28
- 102. A suite of tools device AccessLogReader extends StoppableDevice { source line as String; } a DSL to describe SCC applications context AccessLogParser as Access { source line from AccessLogReader; } context AccessingProfile as IdentifiedAccess { context AccessLogParser; context IP2Profile; } context IP2Profile as Profile indexed by ip as IPAddress { [GPCE’09] source ip2host from NSLookup; source host2profile from LDAPServer; } controller ProfileLogger { context AccessingProfile; action Log on Logger; } a simulator with 2D rendering [Mobiquitous’09] + [Demo at PERCOM’09] 29
- 103. Pantagruel a graphical language to prototype pervasive computing applications SENSORS CONTROLLERS ACTUATORS showerdoor R3 showerdoor AND state is CLOSED 1 state is OPEN 2 mixingvalve mixingvalve regulate(WARM) R4 run() OR stop() showermotion showermotion detected is true detected is false [DSL’09] + [Demo at PERCOM’10] 30
- 104. A suite of tools device AccessLogReader extends StoppableDevice { source line as String; } a DSL to describe SCC applications context AccessLogParser as Access { source line from AccessLogReader; } context AccessingProfile as IdentifiedAccess { context AccessLogParser; context IP2Profile; } context IP2Profile as Profile indexed by ip as IPAddress { [GPCE’09] source ip2host from NSLookup; source host2profile from LDAPServer; } controller ProfileLogger { context AccessingProfile; action Log on Logger; } a simulator with 2D rendering [Mobiquitous’09] + [Demo at PERCOM’09] SENSORS showerdoor CONTROLLERS R3 ACTUATORS showerdoor a graphical language to prototype pervasive computing applications AND state is CLOSED 1 state is OPEN 2 mixingvalve mixingvalve regulate(WARM) R4 run() [DSL’09] + [Demo at PERCOM’10] OR stop() showermotion showermotion detected is true detected is false 31
- 105. A suite of tools device AccessLogReader extends StoppableDevice { source line as String; } a DSL to describe SCC applications context AccessLogParser as Access { source line from AccessLogReader; } context AccessingProfile as IdentifiedAccess { context AccessLogParser; context IP2Profile; } context IP2Profile as Profile indexed by ip as IPAddress { [GPCE’09] source ip2host from NSLookup; source host2profile from LDAPServer; } controller ProfileLogger { context AccessingProfile; action Log on Logger; } a simulator with]2D rendering 0 PERC OM+1 ’ [ Dem o at[Mobiquitous’09] [Demo at PERCOM’09] SENSORS showerdoor CONTROLLERS R3 ACTUATORS showerdoor a graphical language to prototype pervasive computing applications AND state is CLOSED 1 state is OPEN 2 mixingvalve mixingvalve regulate(WARM) R4 run() [DSL’09] + [Demo at PERCOM’10] OR stop() showermotion showermotion detected is true detected is false 31
- 106. Conclusion • Existing ADLs do not automate conformance checking • Our ADL is dedicated to SCC applications • Implementation is • driven by the framework • correct by construction http://diasuite.inria.fr 32
- 107. Conclusion & Future Work • Existing ADLs do not • Architecture-driven automate conformance checking • testing • Our ADL is dedicated to • analysis SCC applications • Non-functional properties [splash’10] • Implementation is • driven by the framework • Validation with a customer • correct by construction • Generalization to other architectural styles http://diasuite.inria.fr 32
Editor's Notes
- standard ADL => poor expressiveness => few support
- standard ADL => poor expressiveness => few support
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- instanciate the pattern (environment = webserver) role of this application?
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- Too few description => too many implementations => no support
- present the formalisation => use it to describe the rest Problem then solution