Ruby Driver Explained: DataStax Webinar May 5th 2015
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Apache Cassandra is the leading distributed database platform purpose built for the demands of today's modern Web, Mobile, and IOT applications. To support this growing demand, DataStax makes it a priority to deliver drivers to support today's most common and cutting edge languages. Join Bulat Shakirzyanov, Software Engineer at DataStax, as he dives into the inner-workings of the DataStax Ruby Driver for Apache Cassandra. He will: • Provide a brief overview of Apache Cassandra's architecture and various terminology • Walk through the basics for installing and using the DataStax Ruby Driver • Drill into exactly why the Ruby Driver is fully asynchronous, both from the IO implementation as well as the Cassandra native protocol design • Look at how the driver uses load balancing policies as well as use cases for various built-in load balancing policies, such as token aware and data center aware round-robin • Discuss in detail the driver's error handling and fault tolerance and discuss various expected failure modes and how to handle them • Explain the importance of address resolution policies and take a look at those that ship with the driver
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Ruby Driver Explained: DataStax Webinar May 5th 2015
- 1. Apache Cassandra Ruby Driver explained
- 3. © 2015 DataStax, All Rights Reserved. Datacenter Datacenter Cassandra Topology 3 Node NodeNode Node Client Client Node NodeNode Node Client Client Cluster
- 4. © 2015 DataStax, All Rights Reserved. Datacenter Datacenter Request Coordinator 4 Node NodeNode Node Client Client Node NodeCoordinator Node Client Client Coordinator node: Forwards requests to corresponding replicas
- 5. © 2015 DataStax, All Rights Reserved. Datacenter Row Replica 5 Replica NodeNode Replica Client Client Datacenter Node Node Replica Client Client Coordinator Replica node: Stores a slice of total rows of each keyspace
- 6. Quick Start Installation and Usage
- 7. © 2015 DataStax, All Rights Reserved. Installation 7 gem 'cassandra-driver', '~> 1.0.0' gem install cassandra-driver
- 8. © 2015 DataStax, All Rights Reserved. Usage 8 require 'cassandra' cluster = Cassandra.cluster cluster.each_host do |h| puts "Host #{h.ip}: datacenter=#{h.datacenter} rack=#{h.rack}" end keyspace = 'system' session = cluster.connect(keyspace) future = session.execute_async('SELECT * FROM schema_columnfamilies') future.on_success do |rows| rows.each do |row| puts “Table: #{row[‘keyspace_name']}.#{row['columnfamily_name']}" end end future.join
- 9. Asynchronous Execution IO Reactor, Request Pipelining and Future Composition
- 10. © 2015 DataStax, All Rights Reserved. Asynchronous Core 10 Application Thread Business Logic Driver Background Thread IO Reactor
- 11. © 2015 DataStax, All Rights Reserved. Request Pipelining 11 Client Without Request Pipelining Server Client Server With Request Pipelining 1 2 2 3 1 3 1 2 3 1 2 3
- 12. © 2015 DataStax, All Rights Reserved. Future Composition 12 select_user = session.prepare("SELECT * FROM users WHERE id = ?") select_page = session.prepare("SELECT * FROM pages WHERE slug = ?") user_ids = [1, 2, 3, 4] futures = user_ids.map do |id| future = session.execute_async(select_user, id) future.then do |users| user = users.first future = session.execute_async(select_page, user[‘username']) future.then do |pages| page = pages.first User.new(user, Page.new(page)) end end end Cassandra::Future.all(futures).get
- 13. © 2015 DataStax, All Rights Reserved. Future Composition 13 select_user = session.prepare("SELECT * FROM users WHERE id = ?") select_page = session.prepare("SELECT * FROM pages WHERE slug = ?") user_ids = [1, 2, 3, 4] futures = user_ids.map do |id| future = session.execute_async(select_user, id) future.then do |users| user = users.first future = session.execute_async(select_page, user[‘username']) future.then do |pages| page = pages.first User.new(user, Page.new(page)) end end end Cassandra::Future.all(futures).get
- 14. © 2015 DataStax, All Rights Reserved. Future Composition 14 select_user = session.prepare("SELECT * FROM users WHERE id = ?") select_page = session.prepare("SELECT * FROM pages WHERE slug = ?") user_ids = [1, 2, 3, 4] futures = user_ids.map do |id| future = session.execute_async(select_user, id) future.then do |users| user = users.first future = session.execute_async(select_page, user[‘username']) future.then do |pages| page = pages.first User.new(user, Page.new(page)) end end end Cassandra::Future.all(futures).get
- 15. © 2015 DataStax, All Rights Reserved. Future Composition 15 select_user = session.prepare("SELECT * FROM users WHERE id = ?") select_page = session.prepare("SELECT * FROM pages WHERE slug = ?") user_ids = [1, 2, 3, 4] futures = user_ids.map do |id| future = session.execute_async(select_user, id) future.then do |users| user = users.first future = session.execute_async(select_page, user[‘username']) future.then do |pages| page = pages.first User.new(user, Page.new(page)) end end end Cassandra::Future.all(futures).get
- 16. © 2015 DataStax, All Rights Reserved. Future Composition 16 select_user = session.prepare("SELECT * FROM users WHERE id = ?") select_page = session.prepare("SELECT * FROM pages WHERE slug = ?") user_ids = [1, 2, 3, 4] futures = user_ids.map do |id| future = session.execute_async(select_user, id) future.then do |users| user = users.first future = session.execute_async(select_page, user[‘username']) future.then do |pages| page = pages.first User.new(user, Page.new(page)) end end end Cassandra::Future.all(futures).get
- 17. © 2015 DataStax, All Rights Reserved. Future Composition 17 select_user = session.prepare("SELECT * FROM users WHERE id = ?") select_page = session.prepare("SELECT * FROM pages WHERE slug = ?") user_ids = [1, 2, 3, 4] futures = user_ids.map do |id| future = session.execute_async(select_user, id) future.then do |users| user = users.first future = session.execute_async(select_page, user[‘username']) future.then do |pages| page = pages.first User.new(user, Page.new(page)) end end end Cassandra::Future.all(futures).get
- 18. © 2015 DataStax, All Rights Reserved. Future Composition 18 [#<User @id=1 @username="avalanche123"; @page=#<Page @slug="avalanche123" ... > ... >, ... ]
- 19. Load Balancing Principles and Implementations
- 20. © 2015 DataStax, All Rights Reserved. Application Driver Load Balancing 20 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy
- 21. © 2015 DataStax, All Rights Reserved. Application Driver Load Balancing 20 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy
- 22. © 2015 DataStax, All Rights Reserved. Application Driver Load Balancing 20 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy
- 23. © 2015 DataStax, All Rights Reserved. Datacenter Datacenter DataCenter Aware Balancing 21 Node Node NodeClient Node Node Node Client Client Client Client Client Local nodes are queried first, if non are available, the request could be sent to a remote node.
- 24. © 2015 DataStax, All Rights Reserved. Token Aware Balancing 22 Route request directly to Replicas Node Node Replica Node Client Replica Replica Uses prepared statement metadata to get the token
- 25. Fault Tolerance Sources of Failure and Error Handling
- 26. © 2015 DataStax, All Rights Reserved. Fault Tolerance 24 Coordinator Node Replica Replica Replica Node Business Logic Driver Application
- 27. © 2015 DataStax, All Rights Reserved. 25 Coordinator Node Replica Replica Replica Node Business Logic Driver Application Invalid Requests Network Timeouts Server Errors Possible Failures
- 28. © 2015 DataStax, All Rights Reserved. Application Driver Automatic Retry of Server Errors 26 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy
- 29. © 2015 DataStax, All Rights Reserved. Application Driver Automatic Retry of Server Errors 26 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy
- 30. © 2015 DataStax, All Rights Reserved. Application Driver Automatic Retry of Server Errors 26 Application Thread Node Pool Session Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Load Balancing Policy
- 31. © 2015 DataStax, All Rights Reserved. 27 Coordinator Node Replica Replica Replica Node Business Logic Driver Application Unreachable Consistency
- 32. © 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 28 Replica Business Logic Driver Application Read / Write Timeout Error
- 33. © 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 28 Replica Business Logic Driver Application Read / Write Timeout Error
- 34. © 2015 DataStax, All Rights Reserved. Coordinator Node Replica Replica Node 28 Replica Business Logic Driver Application Read / Write Timeout Error read / write timeout
- 35. © 2015 DataStax, All Rights Reserved. 29 Coordinator Node Replica Replica Replica Node Business Logic Driver Application Unavailable Error
- 36. © 2015 DataStax, All Rights Reserved. 29 Coordinator Node Replica Replica Replica Node Business Logic Driver Application Unavailable Error unavailable
- 37. © 2015 DataStax, All Rights Reserved. 30 Error Handling
- 38. Address Resolution Topology Aware Client
- 39. © 2015 DataStax, All Rights Reserved. Datacenter Datacenter Multiple Addresses 32 Node NodeNode Node Client Client Node NodeNode Node Client Client Within Datacenter: Private IPs Across Datacenters: Public IPs
- 40. © 2015 DataStax, All Rights Reserved. Application Driver Address Resolution 33 Application Thread Application Thread Application Thread Client Cluster
- 41. © 2015 DataStax, All Rights Reserved. Application Driver Address Resolution 33 Application Thread Node Cluster Application Thread Application Thread Client Cluster Address Resolution Policy
- 42. © 2015 DataStax, All Rights Reserved. Application Driver Address Resolution 33 Application Thread Node Cluster Application Thread Application Thread Client Cluster Node Node Node Address Resolution Policy Control Connection
- 43. © 2015 DataStax, All Rights Reserved. Application Driver Address Resolution 33 Application Thread Node Cluster Application Thread Application Thread Client Cluster Node Node Node Address Resolution Policy Control Connection
- 44. © 2015 DataStax, All Rights Reserved. Application Driver Address Resolution 33 Application Thread Node Pool Cluster Pool Pool Pool Application Thread Application Thread Client Cluster Node Node Node Address Resolution Policy Control Connection Session
- 45. © 2015 DataStax, All Rights Reserved. EC2 Multi-Region Address Resolution 34
- 46. Questions and Links • Documentation • Code • Example Web-app