Advertisement
Welcome to the (state) machine @ Crafted Software
Report
Mauro ServientiFollow
Dec. 14, 2018•0 likes•180 views
1 likes
Be the first to like this
Show More
views
Total views
0
On Slideshare
0
From embeds
0
Number of embeds
0
Check these out next
Welcome to the (state) machine @ Crafted Software
Dec. 14, 2018•0 likes•180 views
1 likes
Be the first to like this
Show More
views
Total views
0
On Slideshare
0
From embeds
0
Number of embeds
0
Download to read offline
Report
Software
Stateless all the thing, they say. In the last few years we’ve been brainwashed: design stateless systems, otherwise they cannot scale, they cannot be highly available, and they are hard to maintain and evolve. In a nutshell stateful is bad. However complex software systems need to do collaborative processing, that is stateful by definition. Stateless myth busted! Collaborative domains deal with long business transactions and need to interact with distributed resources. The traditional distributed transactions approach, even if tempting, is a time bomb. This is when Sagas come into play. Sagas allow to model complex collaborative domains without the need for distributed transactions and/or orchestration across multiple resources. Join Mauro on a journey that aims to disclose what sagas are, how they can be used to model a complex collaborative domain, and what role they play when it comes to designing systems with failure and eventual consistency in mind. (It’s all right, I know we’re you’ve been)
Mauro ServientiFollow
Advertisement
Advertisement
Advertisement
Recommended
Welcome to the (state) machine @ ExploreDDD 2019Mauro Servienti
Designing a ui for microservices @ .NET Day Switzerland 2019Mauro Servienti
Welcome to the (state) machine @ Xe One Day Enterprise ApplicationsMauro Servienti
All our aggregates are wrong @ NDC Copenhagen 2019Mauro Servienti
Be like water, my friend @ Agile for Innovation 2019Mauro Servienti
Microservices architecture is it the right choice to design long-living syste...Mauro Servienti
Welcome to the (state) machine @ Crafted Software
- @mauroservienti welcome to the (state) machine It’s all right, I know where you’ve been
- @mauroservienti All I want to do when I wake up in the morning is… (cit. Rosanna, Toto, Toto IV)
- @mauroservienti
- @mauroservienti tickets web site buy a ticket stage dive… :-)
- @mauroservienti All what they want to do is…
- @mauroservienti
- @mauroservienti display available tickets reserve with the theater charge my credit card deal with insurance ship tickets deal with their stuff
- @mauroservienti sometimes order doesn’t matter sometimes it does!
- @mauroservienti spot the
- @mauroservienti my ticket Warehouse Insurance
- @mauroservienti issuesOwnership is lost
- @mauroservienti
- @mauroservienti chop up
- @mauroservienti
- @mauroservienti
- @mauroservienti The (state) machine ticket ordering process
- @mauroservienti reserve with the theater charge my credit card deal with insurance ship tickets deal with their stuff The (state) machine
- @mauroservienti reservation payment insurance shipping stuff The (state) machine
- @mauroservienti Process Manager Connecting the dots…
- @mauroservienti Credit Card Gateway/ACL Orders Manager Checkout request Block off money request/response Reservation Gateway/ACL Reservation request/response Credit Card Gateway/ACL Charge credit card request/response Insurance Gateway/ACL Tickets Insurance request/response Shipping Gateway/ACL Ship tickets request/response 2-phase commit / timeout …
- @mauroservienti like a Punch Card, a Process Manager owns the process
- @mauroservienti Process Manager (a different point of view) New requirement: collect tickets at the venue OrderId ShippingId ShippingStatus Etc 12 1337 Delivered … 58 1338 Pending … Orders table
- @mauroservienti Process Managers: Source of coupling •Single Point of Failure •Violates Single Responsibility Principle •Contention/Performance Bottleneck •Conflicting Changes/Merge Conflicts •Single Unit of Deployment •Data exchange across boundaries
- @mauroservienti user mental model tends to be UI driven
- @mauroservienti there is no Spoon Orders Manager
- @mauroservienti Autonomy Collaborative Domains
- @mauroservienti Sagas
- @mauroservienti multiple workflows, each providing compensating actions for every step of the workflow where it can fail
- @mauroservienti multiple workflows, each providing compensating actions for every step of the workflow where it can fail
- @mauroservienti multiple workflows, each providing compensating actions for every step of the workflow where it can fail
- @mauroservienti Shipping Insurance Finance Reservation 1-day timeout to release money Payment Gateway Finance Order Checked-out Initiate Payment Policy Finance Hold money Venue Gateway Reserve seats Seats Reserved Payment Gateway Charge money Payment Succeeded Order Shipped …whatever … Courier Gateway Pick-up Request Tickets Ordering Saga
- @mauroservienti Shipping Insurance Finance Reservation 1-day timeout to release money Payment Gateway Finance Order Checked-out Initiate Payment Policy Finance Hold money Venue Gateway Reserve seats Seats Reserved Payment Gateway Charge money Payment Succeeded Order Shipped …whatever … Courier Gateway Pick-up Request Payment Policy Tickets Ordering Saga
- @mauroservienti New requirement • 12-hours delivery SLA with our customers • if the default shipping courier doesn't respond • contact another one to deliver the package
- @mauroservienti Shipping Insurance Finance Reservation 1-day timeout to release money Payment Gateway Finance Order Checked-out Initiate Payment Policy Finance Hold money Venue Gateway Reserve seats Seats Reserved Payment Gateway Charge money Payment Succeeded Order Shipped …whatever … Courier Gateway Pick-up Request Tickets Ordering Saga
- @mauroservienti Shipping Order Shipped … First Courier Gateway Pick-up Request 8-hours timeout Shipping Have we received a response? Shipping Yes No Second Courier Gateway Pick-up Request Shipping Shipping Policy 2-hours escalation timeout Shipping Have we received a response? Yes No Shipment Failed …
- @mauroservienti Payment Policy Shipping Policy Reservation Policy Seats Reserved Payment Succeeded Release money Order Checked-out fail 1-day timeout to release money Happy path and not so happy path :)
- @mauroservienti Payment Policy Customer Care … Reservation Policy Payment Failed Order Checked-out fail Happy path and not so happy path :)
- @mauroservienti Sagas (a different point of view) OrderId ShippingId ShippingStatus Etc 12 1337 Delivered … 58 1338 Pending … Orders table Sales Shipping Finance Id ProductId 12 ABC 58 ACD Orders table OrderId Address 12 Haifa, Israel 58 Rotterdam, Holland Shipping table OrderId Status 12 Paid 58 Overdue Invoices table VS
- @mauroservienti Sagas •Business Process is distributed •No overarching Process Manager •Respect Single Responsibility Principle •Independent scale out •Simpler/not conflicting evolution •Independent Units of Deployment
- @mauroservienti Takeaways • Boundaries are key to success • Finding boundaries is the hardest part
- @mauroservienti Takeaways • Boundaries are key to success • Mental model can badly influence design • Users/Business analysts tend to think in term of data presentation
- @mauroservienti Takeaways • Boundaries are key to success • Mental model can badly influence design • Behaviors define how to designs processes • Group data that change together • Follow the coupling • Identify processes and chop them up by “service”
- @mauroservienti Takeaways • Boundaries are key to success • Mental model can badly influence design • Behaviors define how to designs processes • Use Delayed Messaging to model time • Simplifies making decisions in an async world
- @mauroservienti | #EDDD Mauro Servienti Solution Architect @ Particular Software the makers of NServiceBus mauro.servienti@particular.net @mauroservienti //milestone.topics.it
- @mauroservienti | #EDDD Thank you!
Editor's Notes
- Ritmo tribale Litfiba
- Let me tell that you of that time when {the vendor I cannot name} gifted me with a nice {flat x86 device with a very thin keyboard} {the story} It’s obvious that there are two very different point of views here.
- Temporal coupling
- Compensation
- Idempotency
Advertisement