1. Software Architecture in Practice
Cloud Computing

2. Computer utilities Leonard Kleinrock, ARPANET, 1969:
”We will probably see the spread of computer utilities, which like electricity will service individual homes and offices.”
ARPANET was the precursor to the internet
Leonard with an Interface Message Processor, the first generation of routers
Henrik B Christensen

3. An example ViewCare tele medicine (www.viewcare.com)
Video conference + measurement upload
Device in home + Clinician computer at hospital
Challenges in experiments
Storing measurements Where?
Ideal
At regional hospital’s data centers
But
”Not our data”
No control
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4. An example Bottomline But expensive for small company!
ViewCare hosts their own data center
Complete control
Fast recovery in case of failure
Customers see good support!
Migration of formats etc.
Can always later migrate to other formats/suppliers
But expensive for small company!
What if data center management is not a SMB’s lead competence?
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5. Another problem How to you scale it properly?
1000 servers for 10 patients
1 server for 1000 patients?
What happens in case of market success?
Computation as a utility
Electricity and water I pay per usage
How many spare CPU cycles do you have at home?
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6. Utilization problem Either you Waste hardware resources or
Cannot provide service during peaks 
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7. Cloud Definitions
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8. Ambrust et al.
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9. Buyya et al.
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10. Vaquero et al. Based up review of a lot of definitions:
Clouds are a large pool of easily usable and accessible virtualized resources (such as hardware, development platforms and/or services). These resources can be dynamically re-configured to adjust to a variable load (scale), allowing also for an optimum resource utilization. This pool of resources is typically exploited by a pay-per-use model in which guarantees are offered by the Infrastructure Provider by means of customized SLAs.
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11. Comparing? Similarities? Differences?
Clouds are a large pool of easily usable and accessible virtualized resources (such as hardware, development platforms and/or services). These resources can be dynamically re-configured to adjust to a variable load (scale), allowing also for an optimum resource utilization. This pool of resources is typically exploited by a pay-per-use model in which guarantees are offered by the Infrastructure Provider by means of customized SLAs.
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12. NIST characteristics
Comparing
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13. A key enabling technology: Virtualization
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14. Henrik Bærbak Christensen
Credits
Some slides from
E Virtual Machines Lecture 2 CPU Virtualization
Scott Devine
VMware, Inc. AU
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15. Henrik Bærbak Christensen
What is it?
vir•tu•al (adj):
existing in essence or effect, though not in actual fact
Example
ScummVM is a program which allows you to run certain classic graphical point-and-click adventure games, provided you already have their data files. The clever part about this: ScummVM just replaces the executables shipped with the games, allowing you to play them on systems for which they were never designed! AU
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16. Henrik Bærbak Christensen
A Physical Machine
Hardware
Processors, devices, memory, etc.
Software
Built to the given hardware (Instruction Set Architecture, e.g. x86)
Built to given OS (App. Programming Interface, e.g. Win XP)
OS controls hardware AU
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17. Henrik Bærbak Christensen
A Virtual Machine
Hardware Abstraction
Virtual processor, memory, devices, etc.
Virtualization Software
Indirection: Decouple hardware and OS
Multiplex physical hardware across guest VMs AU
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18. Henrik Bærbak Christensen
Why VMs?
Many advantages (often business related)
Utilization of resources
VM1 that idles automatically free resources to VM2
Of course not the case for physical machines
Isolation
Crash, virus, in VM1 does not propagate to VM2
Encapsulation
A VM is a file: (OS,Apps,Data,Config, run-time state)
Content distribution: Demos as snapshots
Snapshot provides recovery point
Migration to new physical machines by snapshot/restore
In e.g. server farms AU
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19. Henrik Bærbak Christensen
Why VMs?
More advantages
Maintenance costs
Maintain 100 Linux-based web server machines versus a few big VM platforms
Legacy VMs
Run ancient apps (like DOS or SCUMM-based games)
Create once, run anywhere
No configuration issues
E.g. complex setup of app suite of database, servers, etc. AU
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20. Henrik Bærbak Christensen
Types of VMs
Smith & Nair 2005
Two superclasses
Process VM
System VM
Both can be subclassed based upon supporting virtualization of same or different ISA (Instruction Set Architecture). AU
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21. Henrik Bærbak Christensen
Process / System VM AU
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Process VM
The process VM puts the virtualization border line at the process line.
A application process/program executes in a
Logical address space (assigned/handled by the OS)
Using user-level instructions and registers (CPU user-mode)
Only do IO using OS calls or High-Level Library(HHL) calls
Thus a process VM becomes a virtual OS in which a process may execute.
Example: Different ISA Process VM
JavaVM defines its own ISA (stack-based) as well as normal OS operations AU
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23. Henrik Bærbak Christensen
System VM
The system VM sets the virtualization border at the system or hardware line
A system/OS executes in a
Physical memory space
Using the full ISA of the underlying machine
Interact directly with IO
Thus a system VM becomes a virtual machine in which a system as a whole may execute
Example: Same ISA System VM
VMWare: Executes Guest OS that is running on the x86 ISA. AU
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New Kid
OS-Layer Virtualization
Sahoo (2010)
Ex:
Docker
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25. Henrik Bærbak Christensen
Or…
From Docker
Traditional VVMs
Docker
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26. Classic Versus Hosted VMs
VMWare Player (free) / Workstation
Ordinary application in Linux/Windows
Classic
VMWare ESXi (free)
Runs on the bare machine
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27. Examples from my back yard
Magnus wants to play Titan Quest
On his new MSI Windows 10 gaming laptop
Titan Quest does not run on Win10
Solution: Win XP SP3 installed on VMWare Player
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28. More examples...
Crunch3 machine was the production machine to do awesome stuff in another course I am running
It runs on my local ESXI
But, but – our students could not see it!
Moved to the AUIT vSphere infrastructure
VMWare converter…
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29. Henrik Bærbak Christensen
My ‘Private Cloud’ 
DAIMI
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30. Henrik Bærbak Christensen
VMWare ESXi
(Linux based) Minimal OS
My ‘Rundo’ runs from the USB stick
… and drivers were hell 
Download Mgt application from its web server
DAIMI
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31. Henrik Bærbak Christensen
A Small VMM
Remote client to access the VMM
DAIMI
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A Much Bigger VVM
DAIMI
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A Large VVM
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34. Characteristics
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35. Operations
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36. Service Models SaaS: Software as a service PaaS: Platform as a service
End user applications accessible in the cloud, typically through web browsers
Exercise: Give examples
PaaS: Platform as a service
Programming libraries, services, tools allowing applications to be build utilizing cloud features
Exercise: Give examples
SaaS: Gmail, google maps, google docs, ....
PaaS: Google App Engine
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37. Service Models IaaS: Infrastructure as a Service
Provide virtual processing and storage capacity, i.e. the actual computing infrastructure
Exercise: Give examples
IaaS: Amazon EC2
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38. Comparing
Why are some cloud service models much easier to spot than others?
Because PaaS is hidden from us users? Was this web site made using App Engine?
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39. Example: NetFlix Adrian Cockcroft / GOTO 2012 CS@AU
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40. Deployment models NetFlix also moves more and more to EC2 CS@AU
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41. Obstacles/Opportunities
Armbrust et al.
Business Continuity and Service Availability
If your cloud provider fails – you fail
Data Lock-in
Storage using propriatary API (Amazon S3 etc.) makes ‘getting your data back’ hard
Data Confidentiality/Auditability
Who peeks into my data?
Data Transfer Bottlenecks
Sending data is costly. Shipping disks are cheaper!
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42. Obstacles/Opportunities
Ambrust et al.
Performance Unpredictability
Multiple VMs (one the same physical machine) can limit IO – i.e. cross-VM penalties
Scaleable Storage
Storage is not as easily scaled as other resources
? Is this an issue of yesterday?
Bugs in Large Scale Dist. Systems
How do you debug?
NetFlix: Monkeys and Gorillas
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43. Obstacles/Opportunities
Ambrust et al.
Scaling Quickly
What to do with idling machines? Shutting down means longer time to start...
Reputation Fate Sharing
Spamming -> black listed IP addresses.
Will you overtake these?
Software Licensing
Pay as you go licenses for commercial SW
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44. Experiences from CLC Bio
EC2 virtualization makes storage behave rather unfamiliar...
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45. Summary I think it is here to stay  I have started to use it a lot
Unfortunate, but… Much faster to deploy stuff at DigitalOcean than at AUIT
But much more expensive, and staff is not readily around to ask…
Henrik B Christensen