1. Copyright 2013-15 1 COMP 2410 – Networked Information Systems IC1 – The Architectures of Networked Applications Roger Clarke Xamax Consultancy, Canberra Visiting Professor, A.N.U. and U.N.S.W. http://www.rogerclarke.com/II/NIS2410.html#L1 http://www.rogerclarke.com/II/NIS2410-1 {.ppt,.pdf} ANU RSCS, 18 March 2015

2. Copyright 2013-15 2 Application Architectures Agenda 1.The Notion of 'Architecture' 2.Alternative Architectures:.1Master-Slave Architecture.2Client-Server Architecture Cloud Computing.3Peer-to-Peer (P2P) Architecture 3.Networks without People

3. Copyright 2013-15 3 Architecture Elements and their Inter-Relationships The way components fit together The term applies to any complex system e.g. buildings, logistical networks, human organisations, computer networks, software Encompasses static components May encompass processes as well

4. Copyright 2013-15 4

5. Copyright 2013-15 5 Elements of Internet Architecture Computers, incl. hosts and workstations Communications Links between computers: Physical Media (e.g. cables, telephone lines) Wireless Media (e.g. microwave, cellular phone)

6. Copyright 2013-15 6 Elements of Internet Architecture Computers, incl. hosts and workstations Communications Links between computers: Physical Media (e.g. cables, telephone lines) Wireless Media (e.g. microwave, cellular phone) Protocols defining the rules of engagement between the elements Software running on computers Human Processes to create and amend protocols Governance Mechanisms

7. Copyright 2013-15 7 Elements of Internet Architecture Computers, incl. hosts and workstations Communications Links between computers: Physical Media (e.g. cables, telephone lines) Wireless Media (e.g. microwave, cellular phone) Protocols defining the rules of engagement between the elements Software running on computers: Clients (which are directly used, e.g. by people) Servers (which provide services to Clients) Intermediating Nodes, e.g. gateways and proxy-servers (which pass traffic onwards) Human Processes to create and amend protocols Governance Mechanisms

8. Copyright 2013-15 8 1.Master-Slave Architecture Star Topology

9. Copyright 2013-15 9 The 'PC’ Era – Mid-Late 1970s Onwards

10. Copyright 2013-15 10 2.Client-Server Architecture Mid-1980s Onwards

11. Copyright 2013-15 11 Client-Server Architecture – Internet-Mediated Mid-1990s Onwards

12. Copyright 2013-15 12 Client-Server – 'The Cloud' 'Server Virtualisation' Cloudsourcing Outsourcing of Applications (SaaS) of Platform incl. OS, dev tools (PaaS) of Infrastructure incl. air-con (IaaS) http://www.rogerclarke.com/II/CCBR.html

13. Copyright 2013-15 13 Business Computing From Insourcing to Outsourcing 'Off-Site Hosting' 'Outsourced Facility'

14. Copyright 2013-15 14 From Insourcing to Cloudsourcing CloudSourced Facilities

15. Copyright 2013-15 15 Business Cloudsourcing How is it different from Outsourcing generally? Scalability ('there when it's needed') Flexible Contractual Arrangements ('pay per use') Opaqueness ('let someone else worry about details') which means less user control: of the Application, through commoditisation of Service Levels, through SLA dependence (assuming there's an SLA, and it's negotiable) of Host Location, through resource-virtualisation

16. Copyright 2013-15 16 Levels of Cloudsourcing Software as a Service (SAAS) Google Gmail, Google Drive/Docs/Apps MS Office 365 Dropbox Salesforce MYOB LiveAccounts, Intuit Online Platform as a Service (PaaS) MS Azure, Sware Dev Environments,... Infrastructure as a Service (IaaS) Amazon EC2, Rackspace,...

17. Copyright 2013-15 17 SaaS, incl. Consumer Computing Email clients, using smtp/pop/imap Personal Web-Sites Dedicated Devices Office on the Desktop FTP-server and -client Webmail, using http / https Flickr, Picasa iTunes Zoho, Google Docs Dropbox Functions Applications ==>> Services 1975-2000 2000- Email Personal Galleries Personal Music Doc Prep File-Sharing http://www.rogerclarke.com/EC/CCC.html#CAS

18. Copyright 2013-15 18 Consumer Requirements and Risks – 1 of 3 The Basic Needs Does it do what I want it to do? [Fit] Will it be there when I want it? [Availability, Reliability]

19. Copyright 2013-15 19 Consumer Requirements and Risks – 1 of 3 The Basic Needs Does it do what I want it to do? [Fit] Will it be there when I want it? [Availability, Reliability] The Basic Protections How do I keep going if it stays fallen over for a long time? [Service Interruptions] Will you respond helpfully and quickly enough when I ask for help? [Customer Service] Will you lose my data, or muck it up? [Data Integrity] Do I get my data back if you fall over or withdraw the service? [Survival] Can I move my data to another supplier? [Lateral Compatibility] Who can I complain to if I get dudded, and will they actually help me? [Consumer Protection]

20. Copyright 2013-15 20 Consumer Requirements and Risks – 1 of 3 The Basic Needs Does it do what I want it to do? [Fit] Will it be there when I want it? [Availability, Reliability] The Basic Protections How do I keep going if it stays fallen over for a long time? [Service Interruptions] Will you respond helpfully and quickly enough when I ask for help? [Customer Service] Will you lose my data, or muck it up? [Data Integrity] Do I get my data back if you fall over or withdraw the service? [Survival] Can I move my data to another supplier? [Lateral Compatibility] Who can I complain to if I get dudded, and will they actually help me? [Consumer Protection]

21. Copyright 2013-15 21 Consumer Requirements and Risks – 2 of 3 More Advanced Needs Will it keep doing what it does now? [Service Integrity] Will it stay up-to-date? [Future Fit] Will it fall over too often? [Robustness] Will it come back quickly after it falls over? [Resilience] Is my service protected against you, them and the gods? [Service Security] If bits of it are broken, will you fix it without breaking it some more? [Maintainability] Can I fiddle with it a bit if I need to? [Flexibility] Can I move my data to an upgraded version? [Forward Compatibility] How long will old versions keep working for me? [Backward Compatibility] Am I breaking the law if I use the service? [Legal Compliance]

22. Copyright 2013-15 22 Consumer Requirements and Risks – 3 of 3 More Advanced Protections Am I going to get gouged? [Cost] Can only appropriate people get in and do things? [Authentication and Authorisation] Can I get access to all data that you hold about me? [Subject Access] Is my data protected against you, them and the gods? [Data Security] Is my privacy protected against you, them and the gods? [Privacy Controls] If I terminate our relationship, will my data be irretrievably deleted? [Fully Effective Withdrawal] What happens to my data if I die? [Archival / Memorialisation] http://www.rogerclarke.com/EC/CCC.html#CRR

23. Copyright 2013-15 23 Key Developments Since the Mid- 1990s Workstation Capacity (now rivals Hosts) Workstation Diversity (vast, expanding) desktops, laptops, handhelds, smartcards,... phones ==> smartphones, PDAs ==> tablets,... carburettors, fridges,... RFID tags,... 'things' / IoT Broadband Connectivity (widespread) This enables dispersion and replication of devices capable of providing services Wireless Connectivity (increasingly widespread) This enables Mobility which means Devices change networks which means their IP-addresses change

24. Copyright 2013-15 24 Computing Power ‘at the Edge’

25. Copyright 2013-15 25 3.Peer-to-Peer (P2P) Architecture The Cooperative Use of Resources at the Edge

26. Copyright 2013-15 26 P2P – The Motivation Take advantage of resources that are available at the edges of the Internet Make each participating program both a Client and a Server Each Workstation is also a Host, e.g. a music playstation can be a mixer too a PC can host part of a music repository a tablet could host part of a music catalogue

27. Copyright 2013-15 27 The P2P Server-Component’s Multiple Functions Network Management Directory Management Object Management Process Management

28. Copyright 2013-15 28 P2P – Towards a Technical Definition P2P is a network architecture in which each node is capable of performing each of the functions necessary to support the network and in practice many nodes do perform many of the functions

29. Copyright 2013-15 29 Important Characteristics of P2P Collaboration is inherent Clients can find Servers Enough Devices with Enough Resources act as Servers for discovery, and as Servers for services ‘Single Points-of-Failure’ / Bottlenecks / Chokepoints are avoided by means of networking dynamics 'Free-Riding' / 'Over-Grazing' of the 'Commons' is restrained through software and psych. features

30. Copyright 2013-15 30 P2P Applications for Access to Digital Objects Entertainment Materials, in various formats

31. Copyright 2013-15 31 P2P Applications for Access to Digital Objects Software: Fixes/Patches Releases Virus Signatures Announcements, e.g. of technical info, business info, entertainment ‘info’, sports results, promotional messages, advertisements News Reports, by news organisations, and by members of the public Emergency Services Data Backup and Recovery Data Games Data, e.g. scenes and battle configurations Archived Messages, for conferencing/chat/IM, and cooperative publishing Learning Materials, in various formats Entertainment Materials, in various formats

32. Copyright 2013-15 32 Networks for 'Things' Artefacts / appliances / 'everyday objects' that have embedded computing and communications capabilities Telemetry Remote data acquisition and reporting SCADA (Supervisory Control And Data Acquisition) Telemetry plus control messages sent back RFID and NFC Tags Attachments to provide short-distance wireless comms The Internet of Things (IoT) A vague term for inter-linking comms-capable artefacts

33. Copyright 2013-15 33 Application Architectures Agenda 1.The Notion of 'Architecture' 2.Alternative Architectures:.1Master-Slave Architecture.2Client-Server Architecture Cloud Computing.3Peer-to-Peer (P2P) Architecture 3.Networks without People

34. Copyright 2013-15 34 COMP 2410 – Networked Information Systems IC1 – The Architectures of Networked Applications Roger Clarke Xamax Consultancy, Canberra Visiting Professor, A.N.U. and U.N.S.W. http://www.rogerclarke.com/II/NIS2410.html#L1 http://www.rogerclarke.com/II/NIS2410-1 {.ppt,.pdf} ANU RSCS, 18 March 2015

35. Copyright 2013-15 35 A Few Drill-Down Slides

36. Copyright 2013-15 36 Levels of Cloudsourcing and What is and isn't Outsourced

37. Copyright 2013-15 37 Cloud Reliability – The First Few Years Inferences from Media Reports (1) Outages are not Uncommon (2) Outages Arise from Multiple Causes (3) Providers' Safeguards are Sometimes Ineffective (4) Failure Cascades are Prevalent (5) Providers have had to be Forced to be Responsive (6) Providers have often been Uninformative (7) Outages may Affect Important Ancillary Services (8) The Direct Impacts have sometimes been Significant (9) Indirect Impacts have often been Even More Significant (10) Few Customers are Recompensed http://www.rogerclarke.com/EC/CCEF-CO.html

38. Copyright 2013-15 38 Why P2P Is Attractive Much-Reduced Dependence on individual devices and sub-networks (no central servers) Robustness not Fragility (no single point-of-failure) Resilience / Quick Recovery (inbuilt redundancy) Resistance to Denial of Service (D)DOS Attacks (no central servers) Much-Improved Scalability (proportionality) Improved Servicing of Highly-Peaked Demand (more devices on the demand-side implies there are also more server-resources)

39. Copyright 2013-15 39 Technical Concerns about P2P Address Volatility: old addresses may not work (hence trust based on repetitive dealings is difficult) Absence of Central Control (hence risk of anarchy) Inadequate Server Participation (over-grazing) Security Challenges: Malware, embedded or infiltrated Surreptitious Enlistment (at least potential) Vulnerability to Masquerade Vulnerability to Pollution Attacks (decoys)