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Teams and monoliths - Matthew Skelton - LondonCD 2016
The document discusses strategies for safely breaking apart monolithic software systems without hindering team dynamics, emphasizing a 'team-first' approach. It outlines a monolith-splitting recipe that includes key steps such as instrumenting the monolith, understanding data flows, aligning teams, and incrementally splitting segments. Additional considerations include cognitive load on teams and the importance of choosing appropriate techniques for segmentation.
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Teams and monoliths - Matthew Skelton - LondonCD 2016
- 1. How to breakapart a monolithic system safely without destroying your team Matthew Skelton, Skelton Thatcher Consulting @matthewpskelton LondonCD meetup: 11 Oct 2016 #londoncd
- 2. Today Cognitive load forteams ‘Monolith’ Code Forensics Team-first boundaries Monolith-splitting recipe
- 3. For now, let’sforget: Microservices CQRS / Event Sourcing Queues (Architectural changes)
- 5. Continuous Delivery /etc… 30+ organisations UK, US, EU, India, China
- 7. How to breakapart a monolithic system safely without destroying your team
- 8. Safer, more rapidchanges to software systems (Business Agility)
- 9. A ‘team-first’ approachto software subsystem boundaries
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- 15. ‘Reverse Conway’ Tobbe Gyllebring(@drunkcod)
- 17. homomorphic force (#Conway #Yawnoc) HT @allankellynet (same) (shape)
- 18. Cognitive load forteams
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- 20. Cognitive load forteams • Driskell et al, 1999 ‘Does Stress Lead to a Loss of Team Perspective?’ Group Dynamics: Theory, Research, and Practice 3, no. 4 (1999): 291. • Fan et al, 2010 ‘Learning HMM-Based Cognitive Load Models for Supporting Human-Agent Teamwork’. Cognitive Systems Research 11, no. 1 (2010): 108–119. • Ilgen & Hollenbeck, 1993 ‘Effective Team Performance under Stress and Normal Conditions: An Experimental Paradigm, Theory and Data for Studying Team Decision Making in Hierarchical Teams with Distributed Expertise’. DTIC Document, 1993. • Johnston et al, 2002 ‘Application of Cognitive Load Theory to Developing a Measure of Team Decision Efficiency’. DTIC Document, 2002.
- 21. “stress impacts team performance… by narrowing or weakening the team-level perspective required for effective team behavior.” – Driskell et al, 1999 Group Dynamics: Theory, Research, and Practice 1999, Vol. 3, No. 4,291-302
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- 23. “Don’t start witha monolith when your goal is a microservices architecture” – Stefan Tilkov, innoQ http://martinfowler.com/articles/dont-start-monolith.html
- 24. “Start monolithic andextract” – Tammer Saleh, Pivotal https://www.infoq.com/presentations/cloud-anti-patterns
- 25. A ‘team-first’ approachto software subsystem boundaries
- 26. Types of softwaremonoliths •Application monolith •Joined at the DB •Monolithic releases (coupled) •Monolithic thinking (standardisation) …
- 27. Application monolith Single block ofcode Deployed as a unit
- 28. Joined at the DB Difficultto change separately (but not impossible) Risk is (probably) elevated Chris Collyer, http://www.stone-circles.org.uk/stone/pentreifan.htm
- 29. Monolithic releases Smaller components bundled togetherinto a ‘release’
- 30. Monolithic thinking ‘One-size-fits-all’ for teams Assumption that minimisingvariation is A Good Thing
- 31. Dangers of splittinga monolith •Reduced domain consistency (UX, Architecture, Data) •Data duplication (unintentional) •Additional operational complexity due to distributed system and async messaging •Degraded UX across the product
- 32. Splitting a monolith Reiner Flassig- CC BY-SA 2.0 de - Wikipedia Choose the right technique for splitting Understand the nature of the monolith
- 34. ‘Fracture planes’ forcode •Business domain bounded context •Regulatory compliance •Change cadence •Risk •Performance isolation •User personas •Team location
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- 36. Forensics Your Code asa Crime Scene Adam Tornhill
- 37. Adam Tornhill Code, Crime,Complexity: Analyzing software with forensic psychology Adam Tornhill TEDxTrondheim youtube.com/watch?v=qJ_hplxTYJw
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- 39. Adam Tornhill, http://www.adamtornhill.com/articles/crimescene/codeascrimescene.htm CodeCity plus Code Maat forensics
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- 41. "information-poor abstract names aremagnets for extra [unwanted] responsibilities" – Adam Tornhill p.185, Your Code as a Crime Scene
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- 44. Team types Component team Platform/ ’substrate’ team Supporting / ‘productivity’ team Product/Feature team
- 45. Team types devopstopologies.com Component team Platform/ ’substrate’ team Supporting / ‘productivity’ team Product/Feature team
- 46. Code repositories Align repositoriesto subsystem boundaries Avoid monolithic-y repos like TFS* * Don’t get me started on TFS, grrr…
- 47. Code repositories Repo 1Build Test Deploy Run Repo 2 Build Test Deploy Run Repo 3 Build Test Deploy Run
- 48. “You can usea monorepo only if your organisation has published a scientific paper on Computer Science. Otherwise, use one repo per separate deployable thing.” – Matthew Skelton LondonCD meetup group, 11 Oct 2016
- 49. Find natural oravailable ‘fracture planes’ for splitting a monolith (with the team in mind)
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- 51. How to breakapart a monolith without destroying your team 1. Instrument the monolith – logging 2. Grok data flows and fault responses 3. Align teams to available segments 4. Split off segments one-by-one
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- 55. Instrument the monolith CorrelationID Logs Event ID
- 57. use logging asa channel/vector to make distributed systems more testable use logging as a channel/vector to make distributed systems more testable
- 58. Grok data flowsand fault responses
- 59. Grok data flowsand fault responses Correlation ID Event ID Unexpected collaborating subsystems Undetected fault condition
- 60. Grok data flowsand fault responses Correlation ID Event ID Adjust subsystem boundaries Fix poor fault responses
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- 62. Align teams toavailable segments
- 63. Align teams toavailable segments
- 64. Align teams toavailable segments Map to business domain
- 65. Align teams toavailable segments Identify likely components or ‘platform’ elements
- 66. Split off segmentsone-by-one
- 67. Split off segmentsone-by-one
- 68. Split off segmentsone-by-one Separate: - Builds - Infrastructure - Deployments - Versions - Lifecycle
- 69. Team needs /responsibilities / capabilities come first
- 71. How to breakapart a monolith without destroying your team 1. Instrument the monolith – logging 2. Grok data flows and fault responses 3. Align teams to available segments 4. Split off segments one-by-one
- 72. How to breakapart a monolith without destroying your team 1. Instrument the monolith – logging 2. Grok data flows and fault responses 3. Align teams to available segments 4. Split off segments one-by-one * plus a few other things
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- 75. Books & articles •Working Effectively with Legacy Code, by Michael Feathers • Building Microservices by Sam Newman • ‘Managing Cognitive Load for Team Learning’ by Jo Pearce http://12devsofxmas.co.uk/2015/12/day-3-managing-cognitive- load-for-team-learning/
- 76. Training • From Monolithto Microservices (online training) – Sam Newman, author of Building Microservices http://www.oreilly.com/live-training/from-monolith-to- microservices.html
- 77. Talks & slides •What is cognitive load theory and why should you care?, by Jo Pearce - http://www.slideshare.net/JoPearce5/what-is-cognitive- load-theory-5mins • Building Microservices by Sam Newman
- 78. Research papers • Driskell,James E., Eduardo Salas, and Joan Johnston. ‘Does Stress Lead to a Loss of Team Perspective?’ Group Dynamics: Theory, Research, and Practice 3, no. 4 (1999): 291. • Fan, Xiaocong, Po-Chun Chen, and John Yen. ‘Learning HMM-Based Cognitive Load Models for Supporting Human-Agent Teamwork’. Cognitive Systems Research 11, no. 1 (2010): 108–119. • Ilgen, Daniel R., and John R. Hollenbeck. ‘Effective Team Performance under Stress and Normal Conditions: An Experimental Paradigm, Theory and Data for Studying Team Decision Making in Hierarchical Teams with Distributed Expertise’. DTIC Document, 1993. http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA284683. • Johnston, Joan H., Stephen M. Fiore, Carol Paris, and C. A. Smith. ‘Application of Cognitive Load Theory to Developing a Measure of Team Decision Efficiency’. DTIC Document, 2002. http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA525820.
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