Cloud Computing with .Net
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Cloud computing allows accessing computing resources on demand. It provides an architecture that offers flexibility and scalability. A typical cloud architecture has clients, controllers, and workers. An example application uses a master web service to distribute jobs to workers running on local and Amazon EC2 computers. The application demonstrates how existing technologies can be combined in the cloud. Benefits include varying resources, easy configuration, and pay-as-you-grow pricing. Latency must be considered, as queues and multiple servers can improve average response time.
Cloud Computing with .Net
- 1. Cloud Computing with .Net CodeMash 2009 Wes Faler
- 2. Cloud Computing • Just what is “Cloud Computing”? – Is it difficult to get started with the Cloud? • Short answers: – Computing resources on demand. – It’s easier than you think and you likely already know how and just don’t know it.
- 3. Example Cloud Architecture? Worker Client Controller Worker Client Worker
- 4. Typical Cloud Architecture! Web Browser Server Load Web Balancer Server Browser Congratulations! Web Server
- 5. Client Master Essential Parts Of a Distributed Queue Workers Application
- 6. Amazon EC2 Sample Application • The problem: – Use ZabaSearch.com to search public records, obtaining alternate addresses for a person. – They won’t take a data file with thousands of records and do batch processing, but did ok as many searches as we can do using their web site. – I’m too cheap to pay a hundred people to point and click on a website, and doing it with just one is far too slow.
- 7. Amazon EC2 Sample App Master Client (Web Service) Job Jobs & Windows service -Get Jobs Bundles Results calls Master interface - Report Results then uses Core logic -Worker Mgmt • We know all these technologies. • It’s only the technique we really need to study.
- 8. Amazon EC2 Sample App • The Solution: – A core module able to POST to ZabaSearch and scrape data from its HTML. – A database as the queue of names/addresses to check and to hold the results. – A master web service giving out blocks of name/address jobs – A worker service getting jobs and using the core module – A local computer running the worker service – Any number of Amazon EC2 computers running the worker service • Tada! It’s Cloud Ready!
- 9. Database Schema and Job States • Jobs start in “ToDo” status • When a worker requests a bundle, jobs are set to “InProgress”, get an expiration time, and get flagged with the worker’s GUID. • Jobs not done by the expiration time are reset back to “ToDo” and their worker ID cleared. • When workers report results, results are only recorded if the job is still “InProgress” and still assigned to the worker. Such jobs get set to “Done”. • As a courtesy, workers can report that they are abandoning work, which just sets anything “InProgress” assigned to them back to “ToDo” with a cleared worker ID.
- 10. Amazon EC2 Sample App Code Demo • ZabaSearch Core • Master Web Service • Client Interface • Client Service Threading
- 11. Amazon EC2 Sample App Getting It Into The Cloud • Signup, Keys, Security, Security, Security, and Some More Security. • Elastifox – Public AMIs – Instances • Start, Stop, Reboot • Destroy – Bundles – Private AMIs
- 12. Web Servers DB Process Servers Flow Things in a Cloud All using: Virtual Storage PCs Security
- 13. Cloud Hierarchy Michael Sheehan on Jun 24th, 2008 “The Cloud Pyramid”
- 15. In the Cloud, you can… • Rent – Web servers – Load balancers – Database servers – Storage space – Logic • Application • Queue Management/Flow • Vary – Number of each rented item – Location of each rented item
- 16. Types of Distributed Apps Farm Cluster All Can Be In Shared PC A Cloud Grid
- 17. Virtual PC Farm Cluster Grid Cloud 0 to Mini- Pay as you Cash Up front Up front Up front Cluster grow On Availability Dedicated Dedicated Dedicated Statistical Demand Redundancy None Good Good Good Varies General but General but Computing General Specialized Varies Custom Custom
- 18. Low Hanging Fruit • What could you do with a virtual computer in the cloud? – It’s sharable – You control the configuration – Not just rebootable, reformatted-and- reinstalled with a click – Discardable – Cheap – No waiting
- 19. Low Hanging Fruit • Install incremental releases onto a cloud virtual PC – Control the demo environment – Fully validate before release – Restore to initial release easily – Archivable – Remove the client’s configuration from each release’s issue list
- 20. Low Hanging Fruit • Training Applications on cloud virtual PCs – Create one master image and clone on demand – Trainees only need remote desktop access – Easily reset for those adventurous students
- 21. Low Hanging Fruit • A Spare Development PC – Per Developer! – Unit tests, esp. CPU intensive ones – Can start with standard, easily reset, test data – Installer testing without breaking your development environment – Ease handoffs to QA dept – Experiment with time-limited trial libraries without the time limit
- 22. Queuing! We finally have to take it seriously. (My simulation prof would be so happy!) Latency Activation Flow Control
- 23. Queuing: Latency Consider: • 100 requests, each taking 3 seconds on a high end server when done sequentially. • How long does the 1st request take? – 3 seconds. Users love us! • How long does the 100th request take? – 300 seconds. Users hate us. Work every weekend until this is fixed. • 300 seconds? Don’t measure just “Performance”, measure “Latency”. • Which do you test most often?
- 24. Queuing: Latency Consider: • 100 requests, each taking 3+1 seconds on 20 medium virtual servers in a cloud. • How long does the 1st request take? – 3+1 seconds. Users still love us! • How long does the 100th request take? – 20 seconds. Is this ok? • Classical “Performance” dropped, but “Latency” improved drastically. Which actually drives satisfaction more?
- 25. Queuing: Latency Best Case Latency = Time/Item Worst Case Latency = Time/Item * # of items / # of servers Average Latency = Time/Item * (# of items / # of servers) / 2 Clouds likely raise Time/Item slightly but can raise the number of servers drastically. Order the number of servers that will meet your latency needs. Speed up your code! Time/Item still matters.
- 26. Queuing • Activation – What gets activated when an item moves within the queue? – Push vs. Pull? • Flow Control – Are all jobs equal? – Are all processes equal? • What are users doing while they wait for queued items to finish?
- 27. Your life will be easier if you… • Separate your core logic from your cloud communications logic • Put core logic into its own assembly • Objects-In, Objects-Out in your core • Use unit tests for your core • Use an interactive testing tool to debug your core logic – Remember it’ll be much harder to debug once in the cloud! • Consider network connectivity problems when coding recovery logic – Balance reassignment with forgiveness • Design for some local processing
- 28. Costs • Data sent into the cloud, even if your cloud software requested the data. • Data sent out of the cloud, even if your cloud software sent the data. • Data sent within the cloud isn’t typically charged for. • Time your machine instances exist – even if “off”. • CPU time actually used. • RAM available. • Time and size of storage, including uninstantiated machine instances. • Amazon EC2 costs me about $20/month and would be about $100/month for a 24x7 medium power virtual machine. • Transfer large lumps, such as databases, once and keep them in the cloud. It’s faster and cheaper.
- 29. Cloud Computing • Just what is “Cloud Computing”? • Short answer: Computing resources on demand. • Real answer: Architecture Freedom!