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SWE 622- Distributed Systems Project Phase I Eric Barnes, David Chang, David Nelson

SWE 622- Distributed Systems Project Phase I Eric Barnes, David Chang, David Nelson Fisayo Oluwadiya, Xiang Shen. Architecture. Message Format I. For business transactions, the messages are line based and each field is separated by a colon. The format is:

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SWE 622- Distributed Systems Project Phase I Eric Barnes, David Chang, David Nelson

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  1. SWE 622- Distributed Systems Project Phase I Eric Barnes, David Chang, David Nelson Fisayo Oluwadiya, Xiang Shen

  2. Architecture

  3. Message Format I For business transactions, the messages are line based and each field is separated by a colon. The format is: Op:exchangeName:traderName:product:quantity:price:timeStamp: For example: Trader Messages: sell:Exchange1:Trader2:product_one:0:43.53:0: buy:Exchange2:Trader1:product_two:34:0:0: Exchange Messages: sell:Exchange1:Trader2:product_one:0:123.45:1237237965973 buy:Exchange1:Trader2:product_one:756:123.45:1237237970443

  4. Message Format II For clock synchronization , the messages are line based and each field is separated by a colon as well. The format is: Time request from trader to exchange: time:exchangeName:traderName:time Time response from exchange to trader: time:time For example: Trader Messages: time:E1:T2:1237237964619 Exchange Messages: time:1237237964534

  5. Synchronization • Problem: Traders (clients) need to determine the age of a message from Exchanges (servers). • Clocks are not guaranteed to be synchronized. • There may be non-trivial latency in the network • A solution is needed to determine clock-skew and network latency to compensate.

  6. Synchronization • Clients will query Servers for timestamps. • Client will take a timestamp, and send a message to server for server time. • Server will take a timestamp upon receipt and immediately send it back to and the original client. • Client takes another timestamp upon receipt of the server response. • Client will calculate the network latency and clock skew. • Network latency will be one half of the difference between the two client timestamps. • Clock Skew will be the difference between the average of the two client timestamps and the server timestamp. • Client will maintain the clock skews for the Servers it receives messages from and use those values to determine message age.

  7. Synchronization Mechanism Server Client t1 t2 t3 • After acknowledgement message has been received from the server, client will have client timestamps for t1 and t3, and a server timestamp for t2. • Client will assume that the network latency is approximately symmetrical, and that the server processing time is negligible. • The clock offset will be calculated by t2-(t1+t3)/2. • This value will be stored in the client and used to determine message age.

  8. Implementation For Synchronization • Assuming the server processing time is negligible. • Samples are taken every 5 seconds. • Each sample is averaged by three requests. • Only the latest sample is saved.

  9. Deployment For Evaluation • More than one Exchange will be created • More than one trader will be created • Exchanges and traders will be deployed to team member’s laptops and/or GMU servers such as mason.gmu.edu or zeus.ite.gmu.edu

  10. Test Cases For Exchange • Exchange comes online and is ready to accept sell requests • Exchange receives first sell order • Exchange receives first buy order • Exchange is already selling a product and receives another selling order and successfully processes it within set time limit • Exchange is currently processing a buy order and receives another and successfully processes it within set time limit • Exchange is shutdown after processing all orders • Exchange shuts down normally • Exchange crashes

  11. Test Cases For Trader • Trader comes online and is ready to send buy/sell orders • Trader sends buy order • Trader sends sell order • Trader receives confirmation for buy/sell order • Trader doesn’t receive confirmation for buy/sell order within expected time limit • Trader is unable to connect to Exchange • Trader shuts down normally • Trader crashes

  12. FaultSimulation • Simulate clock skew • Modify the system clocks for exchanges and traders • Simulate Exchange/Trader failure • Use kill or task manager to terminate exchanges and traders • Simulate Network failure • Unplug the network cable • Shutdown the NIC, Network switch etc. • Simulate Network latency • Connect the trader and exchange via a SOCKS proxy server • Use open source server such as Simple SOCKS Server for Perl • Modify the code and randomly sleep a few seconds before forwarding the packets

  13. Methods For Verification • Manually run the system and use our eye balls • Check the log files for verification • Possible automation via scripting, such as using Perl Win32::GuiTest etc.

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