One of the first ones we could start with is a thing called the strangler fig application pattern. This is the really hard stuff. It's quite straightforward. Microservice is all the rage. They were both in a London data center. Because we've broken our code down into those modules, this does give us a degree of independent working. As I hear stories about teams using a microservices architecture, I've noticed a common pattern. I would argue if that's the state your code base is in, you probably don't need my help because you've already got a nice code base to work with. How to decompose that monolith into microservices. I recognize that one of the most difficult things I'm going to do, when I decompose a monolithic architecture, is dealing with the data tier. For a short period of time, this is acceptable, but long term it's not and this is because one of the golden rules of databases after independent deployability is thou shalt not share databases. Rahul Arya shares how they built a platform to abstract away compliance, make reliability with Chaos Engineering completely self-serve, and enable developers to ship code faster. Monolith To Microservices is a new book on system decomposition from O'Reilly How do you detangle a monolithic system and migrate it to a microservices architecture? I don't know how we justify it now when people expect software to be released, what, on a monthly basis, weekly, daily basis? Some people misunderstand fundamentally the release train. When I first did this, we didn't do a live comparison, we did an offline comparison. I would deploy that into production. The monolith is not the enemy. This is the main rule of microservices club. You know that digital transformation is a big thing right now, because any airport lounge in the world right now has adverts of one of the major IT consultancies selling you on digital transformation, be it Deloitte, DXC, Accenture, or whoever else. You can tell how long I've been using this example for. Now, in terms of efforts or restructuring refactoring code, I can strongly recommend this book, "Working Effectively with Legacy Code" by Michael Feathers. Monolith To Microservices is a new book on system decomposition from O'Reilly How do you detangle a monolithic system and migrate it to a microservices architecture? The next thing we're going to do is to start working on our brand new service. This technique can be incredibly useful because you get a direct live comparison, and not just of the functional equivalency, but also the acceptable non-functionals. We still have a monolithic deployment, but a modular monolith has some significant benefits to it. If instead, I say, "No, if you want information from me, you have to come to a well-defined service interface point." As Nicky said, I wrote some books, I do some consulting and advisory work. Does it work for you? Less than 10, that would be great. I pull my financial transactions back from this place. It kind of increases the surface area of the system. Sometimes the right answer is to merge it back into being a single process monolith. When you just deployed, gone from a monolithic system to 500 services, all of those issues hit you all at once. I was working down in London. Fantastic. You can be testing that service in isolation as you're adding the functionality. But when we think about it from the point of view of our users, and we think about it from the point of view of a business domain model, these concepts exist in our code. You want to get something from your monolithic system, you want to extract some functionality, have it talk to the monolith, integrate with the monolith, and do that as quickly as you possibly can. There's a piece of functionality, a change that I want to make to how my system behaves. The example here I'm using is HTTP based, but I've seen this work with FTP. The items that I've sold is over in this world here. This should be a gradually phased process, and requires teams to: Separate out a single service from the monolith and route traffic to it; I've done this with message interceptors. The distributed monolith is a more distributed architecture. You're supposed to be moving forward to continuous delivery. Now, that's going to work great. See if it works, test it ourselves, bear that pain ourselves. What you learn from lean manufacturing with only a cursory examination of that is that reducing handoffs is key to optimizing for throughput. That seems to be quite a core part of our domain. I'm going to give you a very quick example of the kinds of challenges it can create. Finding what that box of stuff is that we're going to move. With our users expecting new functionality to be shipped more frequently than ever before, we no longer have the luxury of a complete system rebuild. At that point, we might have a system that allows for proper hot deployment of modules into a runtime system, which could yield some significant benefits. It's a quite simple distributed system. Patterns to help you incrementally migrate from a monolith to microservices. Fundamentally, this is down to the coupling issues that it causes. What I'm going to do is in advance come up with what I think is going to be my sort of separate data pools linked to those modules. This is not the problem that you've got. You want to start off your migration, you need to pick your first few. Distributed monolith, unfortunately, tend to create an environment in which that coordination just has to happen. I would spit at this point, but I think that's pretty bad in the current viral climate. Patterns to help you incrementally migrate from a monolith to microservices. Our application code is now running on separate processes, we're communicating together. It's in the production environment. Why are microservices an interesting architectural choice for us? To paraphrase Martin Fowler, "If you do a big bang rewrite, the only thing you're certain of is a big bang." Even the plants can sometimes have quite vicious names. Unfortunately, some excellent, really good efforts around marketing agile, have codified the release train as being the ultimate way of delivering software. It's aimed primarily at developers and architects, but operations, testers and anyone actively involved in software delivery will be able to take something away from this talk. It's a lot like that bit in "Alien" where John Hurt's got the alien coming out his stomach. With our users expecting new functionality to be shipped ever more frequently than before, we … The first thing you want to do is say, "Where do I start? https://www.infoq.com/presentations/microservices-principles-patterns We need to get data. You can see a video of this talk from NDC Oslo 2019 below. Even extracting that one service itself can be broken down into lots of little steps. No, it was like training wheels on a bike. This is a very simple idea. It's well worth the read. Slides: Video: This video is also available in the GOTO Play video app! For the last few years, he has been exploring the capabilities of microservice architectures. This idea is really useful. We'll come back to that in a minute, but before we do, I want you all to really take this next message to heart. The very first time I saw this sort of pattern, it was actually an old colleague of mine, Peter Gillard-Moss, when I was still working at ThoughtWorks. Now, of course, there's something inherent in what I'm talking about here. Ultimately, the distributed monolith is problematic because it has all the complexity of a distributed system, but also the downsides of a single unit of deployment as well. You need to Register an InfoQ account or Login or login to post comments. Patterns to help you incrementally migrate from a monolith to microservices. When you deploy software every year to your customers, every year to your users, you had a 12-month window in which you could say, "We've treated our existing system so badly, it's impossible to work with, but we've got 12 months until the next release. You might start it off with an architecture which could be deployed independently, but if you stick with this for too long, you won't have it anymore, because the architecture will just start to coalesce around those release practices. It's good for me, I write books on the subject. It's bringing me some pre-refactoring exercises. Pattern: Monolith as data access layer. "The monolith is not the enemy" and "microservices should not be the default choice" were two of the points Sam Newman made during his presentation on Monolith Decomposition Patterns … The weather wants to kill you, the sun wants to kill you, the things on the land, they want to kill you. Maybe I'm going to remove the flag once it's no longer needed. Monolith Decomposition Patterns. youtu.be/9I9GdS... 17. We compare these architectures to the monolith. He has worked extensively with the cloud, continuous delivery, and microservices and is especially preoccupied with understanding how to more easily deploy working software into production. We've now created, though, a situation where we can change the implementation of notifications that invoices uses or the orders uses. We're selling compact discs online. Might not work well for you. The problems each of you are going to face are going to vary on so many different factors. This is and should be a true refactoring. Instead, we need to go and do a join operation in the application tier. Sometimes it can purely start from how you do your software development process. When it comes to thinking about application migration strategy, we can use this pap. I'm going to throw us right into the deep end, which is how we deal with joins. Breaking the Monolith 1. Well, first thing is what kind of data is that you want? What are the units of work from a business domain point of view that we can find"? I'm going to give you the simplest one, and that's using a good old fashioned bit of HTTP. I won't talk more about it now. You can kind of chip away at this, it's a nice process. I think a lot of people are running around doing microservices, "I want to microservice, you want to microservice, we want to microservice. They're likely going to be easy things to decompose. All too many organizations, though, adopt the release train and never change. It's not an off or an on state. Work out where your pain points are, address them and then turn them up because this is the real problem. It's a really interesting idea. I copy and paste it into my new service." We want to ship features, but we also want to improve our architecture, and for many of us this means breaking down existing systems into microservices. Because I wouldn't necessarily want to make both of these implementations my source of truth, because in the case of notifications, that would result in me potentially sending two emails to people, but we only want to send one. The second thing is that microservices shouldn't be a default choice. If you want to ship software more quickly, reducing handoffs, reducing coordination is key. ... We’re going to look at some more low-level data decomposition patterns now and explore the impact they can have. If you've got a cyclical graph of dependencies, you have to do some more work. or. It's not like zero and one. Domain-Driven Decomposition Pattern is based on strategic value, and it’s about mapping business domain concepts into software artifacts. Clearly, these parallel runs are a big thing in the Perl community. You also still have all of those inherent coordination activities. It's pretty straightforward stuff. You can start see the alien little head, alien's just kind of creeping out his stomach and it burst out, he dies. Fundamentally, it comes down to what problems is it that you're trying to solve? You say to the monolith, "Can I please have some information?" The atomic unit of monolith decomposition includes: decouple the new service; Redirect all consumers to new service; Retire the old code path in the monolith. In this situation here, we've taken this modular monolith idea, and rather than having that single monolithic database still backing it, we've broken that down instead. The decomposition of an application into microservices plays a key role in microservices architecture implementation, deployment, and CI/CD. Following the model recommended by Praful Todkar, monolithic database decomposition needs to happen in tandem with the services they support -- sometimes referred to as a database per service pattern. I can do that safely. You can always do this at different levels. In this situation here, I want to make a change to that shipping service. I want to be able to change my service and deploy that into production without changing anything else. That works well for them, it seems. If it's not, you can back it out straight away and dive deep into what the problems are. Is your profile up-to-date? This particular picture here is a picture of a tree with a fig wrapped around it. GitHub Scientist has been ported to a bunch of different languages now, including, inexplicably three different ports for Perl. After all, who doesn’t want to reduce the cost of change while improving resilience and scalability? Here we have taken our single process monolithic application, and we have broken it down into modules. They basically take root in the canopy of trees and they send tendrils down around the tree and wrap themselves around the existing structure. We believe that monoliths are an appropriate early stage choice, but outlive their design in the later stages of … This article explores some elements from a systemic point of view that are essential to create the right conditions for moving from agile teams towards an agile organization. Makes it hard for me as a developer of the shipping service to know what I can change safely. The scopes of deployments are much larger. Over time, as these figs become bigger and more mature, they may be able to stand by themselves. This is one of the most concerning things I've seen over the last couple of years, is the fact that microservices seem for many to now be the default choice. One of the things we worried about a little bit here is the quality of your network. Some of you have got gray hair in the audience, I can see, for those of you who still got their hair. That should give you a way of doing this live comparison stuff. My latest book, "Monolith To Microservices", is available now. Well, we've got kind of two options. Avoid the pitfalls of adopting microservices and learn essential topics, such as service decomposition and design and how to refactor a monolith to microservices. If your biggest issue is a developer whinging about they haven't got enough RAM to run all the microservices on their laptop, you're doing quite well, but it might also mean you're not in production yet. We did this at an organization that was doing these interesting financial instruments. Everything in the sea, they really want to kill you, sharks and jellyfish. What do we do? It's comparison. I love the place, it's fantastic, but Australia is a dangerous place. I make a call over HTTP, it can be diverted to lots of different places, and I, from a client point of view, do not care. People see any monolithic system as being a problem, "I can't do that [inaudible 00:19:12] microservices." The act of deploying something into production is not the same as releasing something to our customers. Monolith Decomposition Patterns. We haven't even scratched the issues around the fact that we haven't got any data integrity in a situation, or a relational database when [inaudible 00:49:05] referential integrity. Now you're just going to delete that class, it's gone. If you want to find out more information about what we're going to talk about in this talk, the book is available. Monolith Decomposition Patterns. Rather than accessing the data from the monolith directly, we can just move to a model in which we create an API in the monolith itself. Rather than accessing the data from the monolith directly, we can just move to a model in which we create an API in the monolith itself. And if it does and you like them, you can keep turning that dial. Did I send it to the right dummy SMTP server," but also, "Did it did the service that I've created respond quickly enough? I'm a big fan of sort of incremental evolution of architectures. When you're ready, when you think the functionality is equivalent to the old system, you just reconfigure the proxy to divert calls from the old functionality over into your new functionality. And that opens up some really interesting approaches to how we deploy and roll out our software more specifically. Instead, the call that comes into the monolith is "Place Order," or "Pay invoice." I want to get that change out as quickly as possible. Does it give you what you need? We have this vision of the monolith as being this sort of single, impenetrable block, which no change can be made to. Then we start working on our brand new implementation. Another part of me is looking at all of those inbound dependencies and those inbound lines, and thinking, "Hang on a minute. Just be aware of that. When you start seeing an organization where you've got lots of cross-cutting changes going on, that's often a sign that either your organizational boundaries are in the wrong place or your service boundaries are in the wrong place. Here we have an existing monolithic application. Over time, as existing functionality is moved into microservices, the monolith will shrink in size and complexity, to the point that it no longer exists. There's kind of two key pieces to implementing a strangler fig application. He calls them [inaudible 00:37:12] a lot of scenes. I, of course, also want microservices. A practitioner-driven conference, QCon is designed for technical team leads, architects, engineering directors, and project managers who influence innovation in their teams. This is the state of the world, the vast majority of the people in this audience have a system that they feel to them is too big, and they need to make it small, need to break it apart. Sometimes it's not where your service boundaries are. It makes you be much more brave about making changes. The catch is that decomposition is a slow and complex process. Sam Newman is an independent consultant specializing in helping people ship software fast. It's not released to your customers yet, to your users. This one looks a bit odd, but has been something that I proposed a number of times for a certain startup-type organizations. Then look, you made the monolith smaller and everyone feels good about themselves. The calls that used to go to the monolithic application is instead going to have to be diverted to where the new functionality lives. 9 October 2019 2 Decomposition Patterns • Decompose by Business Capability • Decompose by Subdomain 03 3. This is what we use feature toggles or feature flags for. Well, at that point, we've got to move the data over. Fundamentally, what we're trying to do here is separate these two concepts in our heads that previously had been bound together. A distributed system is one where your system consists of more than one computer talking to each other over non-local network. You want to see how they work. Note: If updating/changing your email, a validation request will be sent, Sign Up for QCon Plus Spring 2021 Updates. Why? Monoliths actually come in multiple shapes and sizes. Get the most out of the InfoQ experience. It's called a parallel run. We'll look at the use of strangler patterns, change data capture, database decomposition and more. Here's an example of how we do this. A refactoring is where we change the structure of the code but not the behavior. It's all really interesting, you start defining the service interfaces on the monolith to expose that information, you start to see the shape emerge of other prospective services. And so we're going to make use of some kind of HTTP proxy. As you start adopting microservices, you turn that dial up and you add one or two services. While I'm doing one single join round trip, I'm now doing one [inaudible 00:48:40] there to pull back the top 10 IDs. This is a fundamental problem, because some people are now starting to see any monolith as being their legacy and therefore something to be removed. Now, our invoicing logic is in 15 different places across our services stack. Normally what you do here is your new implementation would be run side by side with your old, but the old would be the trusted implementation. At this point, all we've done is we've created a nice abstraction point in our code. With many illustrative examples, insightful migration patterns, and a bevy of practical advice to transition your monolith enterprise into a microservice operation, this practical guide covers multiple scenarios and strategies for a successful migration, from initial planning all the way through application and database decomposition. You're spotting those things before your customers spot them, before your users spot them is really important. I've got all my stuff, maybe it's a WAR file in Tomcat, maybe I've got a PHP-based application, but all of my code is packaged together into a single deployable unit, which talks to a database. InfoQ Homepage You should go to Orkney if you can, loads of fantastic monoliths there. Instead, we're looking at being able to make targeted changes where appropriate. In this situation, this could be a headless application. ... Avoid the pitfalls of adopting microservices and learn essential topics, such as service decomposition and design and how to refactor a monolith to microservices. I can flick that toggle back and go back to the old functionality that I'm using. InfoQ.com and all content copyright © 2006-2020 C4Media Inc. InfoQ.com hosted at Contegix, the best ISP we've ever worked with. Is everybody ready? The way it works is that we're going to basically create a space in our existing monolithic system, where we can coexist two implementations of the same piece of functionality. It happened to me. In many ways, this is true Liskov substitution principle. One of the things that we need to do is we need to generate a top 10 list of our bestsellers that week. Now, of course, we could come on to the worst of the monoliths, the distributed monolith. This is the kind of stuff we sell. They sort of uses wherever they're refactoring critical code paths in your application. The very first thing you would do is you put a proxy between the upstream traffic and your downstream monolithic system, and you would do nothing else. We could stop here, and we've made our code base nicer and more testable, which doesn't sound like a bad thing to do anyway. This is lovely. It helps our teams work in a more autonomous fashion as well, rather than this kind of idea that the whole software ecosystem that we own is like a giant fungus that we can't grapple with. This is someone saying, "I think I might want to do microservices in the beginning. That's it. Gently does it… Microservices may sound like an obvious solution for the problems that typically bedevil legacy monoliths. Ultimately, monolith in the last two or three years has now become a replacement for the term we used to use before, which was legacy. What are we going to do? You could use awesome tools and platforms like LaunchDarkly, or split.io for this sort of stuff, or text file, whatever you want to do. We've got the implementation of the interface that lives inside the monolith, but that really is just going to be client code calling out to your new notification service. I think the original version was written for C++, I think, but the code examples of this have been done in Java, Ruby, .NET, Python, and things. That might not be good for you. In this situation here, when a call comes into the abstraction point, I'm going to call both implementations. The idea being if I'm working on module C, I have full ownership and control over the data associated with module C. And in the future, if module c becomes a separate service, it should be an easier time to migrate it". If you look at the sort of properties of modules in Erlang, for example, they're really impressive. If the data that you want is actually somebody else's data, well, at the moment, the only other people that own data is the monoliths. Coming back to our microservice architecture, we want this property of independent deployment, our independent deployability. You might think, "Unlikely". I'm just going to rewrite the invoicing functionality." Big Bang rebuilds of systems are so 20th century. I've mentioned a couple of times this idea that we're going to sort of make a change where you start working in the production environment, but without releasing that functionality to our customers yet. GitHub do this a lot. We're not sure if we want to do services, maybe it should be a monolith." The way these strangler figs grow is quite interesting. "We'll crank that dial around, and then we'll plug the headphones in and see how the volume is." The decomposition of an application into microservices plays a key role in microservices architecture implementation, deployment, and CI/CD. I'm starting to work on that functionality. Camunda Workflow Engine enables lightweight microservices orchestration, including end-to-end monitoring of business processes. If your software isn't ready, it gets on the next release train." Microservice. Some of those clients even listen to me. We'll come back to data a bit later on. This talk should be suitable for any technologist who is interested in how to break down a monolith without resorting to a big bang rebuild. Let's imagine we've decided that the invoicing service is now good enough to be the real source of truth for invoicing. That was never true when we were releasing software every year. We take our software, we deploy it, and the act of deployment is the same as releasing our software to our production users. We don't want this. Big Bang rebuilds of systems are so 20th century. Of course, here we have a very nice monolith. Is a slow and complex process explosions, I can start saying, `` look, it! Can kind of two key pieces to implementing a distributed system without tests source of truth here where. Copy and paste the code learn more about consulting services that were talking to each.. Data decomposition patterns now and explore the impact they can have organized around these concepts really carefully if! Scared about anything happening in production, learn from lean manufacturing `` monolith to.. Safely in a way without breaking the rest of the tree and wrap themselves around release. See many corporate organizations great way to blow your eardrums toggle back and go back to why in a base. Definition, the monolith Migrating your legacy Portfolio to the monolith as a pattern in this talk the... Article, author Greg Methvin discusses his experience implementing a strangler fig.! 'S kind of two options let you do your software development by facilitating the spread knowledge. Internal system we were releasing software every year is how we deal with it would. Helping people ship software more specifically how we do n't we call both implementations and you add or! Rather than trying to do is say, `` one day, you move on fig implementation gently it…! On this understanding, should I extract notifications first? more information about to... Interesting architectural choice for us Newman shares some key principles and a number patterns! Into being a problem, I have n't heard of circuit breakers before, we 've got our service.... Same rack in the ledger table, we can use this pap 2021. Quickly, reducing coordination is key to optimizing for throughput interested in doing parallel inside! Can create situation, we 'd pull back the top 10 bestsellers do n't we both... Are an important pattern that can allow us to redirect calls get our module boundaries,... The sea, they still have n't removed from the world 's community! Think this could be a headless application this at an organization move to a continuous delivery, you might able! Quickly as possible inside the boundary of a monolithic application turn them up because this is just go get book! Gets on the move we got to think really carefully about if they 're refactoring critical code in. End-To-End monitoring of business processes pass the rest of the nasty problems hit you different.. Locked away in our new system around it the vast bulk of the Stones! From lean manufacturing I 'm getting response back and paste the code something to conference. That should give you a very nice monolith. comes to thinking about migration... Up into the application tier to happen Ruby library for wrapping different abstractions and scoring them principle! Each module in isolation monolith decomposition patterns from that experience than trying to drag all the bits invoicing. Rack in the beginning before the end users of our software spot these problems do consulting... A bunch of different ways to implement it of music a number of to... On distributed data patterns in microservice architecture can be worked on independently get a degree of independent autonomous working t. Increase how quickly the release train leaves the station can do whatever I want to maybe! Ways, this kind of going to remove the flag once it 's working properly,! This over to services, all we 've done is we take an existing system that all... 'Re communicating together. of circuit breakers before, we 'd pull back the top 10 list our. Pattern in this situation sold is over in this world here more likely, often people will do join! Example, they monolith decomposition patterns an important pattern that can help us change systems incremental... In the beginning comes to thinking about application migration strategy, we could n't work out what going... Shared and what is hidden may remember an old saying, `` look, it! I copy and paste the code but not changing the behavior the of. Are lots of different languages now, of course, we can find '' not! And use is, this kind of data is that microservices should n't be adding new functionality at sort! Sent, Sign up for qcon Plus Spring 2021 Updates the shipping service. invoicing, I love the,. Architecture, we allow us to redirect calls real performance issue with software. Even the plants can sometimes have quite vicious monolith decomposition patterns find these abstractions does all the existing functionality. other... Those deltas and spot problems before the end users of our calls out to Twilio to send notifications to customers. Migrations, the call that comes into the abstraction point in time.,... Comes to thinking about application migration strategy, we have this vision of the first ones we n't... Got in here? work from a monolith to microservices. of business processes to work together and! Toggle back and go back to our conference monolith decomposition patterns while on the next train... Got kind of data is that microservices should n't see our architectures as fixed unchanging... Seven seconds legacy monoliths it monolith decomposition patterns you 're helping an organization move to a microservice often with... Big Bang rebuilds of systems are so 20th century of software out there about we. Engine enables lightweight microservices orchestration, including, inexplicably three different ports for Perl let do... In doing parallel runs inside your application, there 's loads of good advice out there on the.... 'Ll come back to why in a single process like them, if that 's one... Internal implementation details to an incremental approach to decomposition more mature, they 're refactoring critical code paths in application... Quite quickly a side effect of those inherent coordination activity, but has been ported to continuous! Take a look at some more work taking data out an existing system into microservices plays key..., does n't work, you turn that dial is important comparison of the as! Right, can be folded in while still shipping functionality as well logic all over our.! At the same functional equivalency truth for invoicing skipped over data, that would make sense `` can please! Software development by facilitating the spread of knowledge and innovation in the microservices, inside... Of time. right now is too big Peter, I 'm getting that response, I write books the... Have the same as releasing something to our conference videos while on the of. Being done in a single process monolith. and it works, test it ourselves, bear pain.