On Thu, Jan 23, 2025 at 9:20 AM Aleksandar Vidakovic <chee...@monkeysintown.com> wrote: > > ... thanks James for the input... I'll try to answer your last couple of > questions from my perspective (read: opinionated... take with a pinch of > salt):
JD: Aleks - thank you. I always learn something from this back and forth with you. > > too clever: the current implementation I suggest that anyone tries to draw a > sequence diagram that explains the flow of execution and make it fit on one > page vs the new proposal will most likely contain less than a handful of > lines. You can apply the same if you take lines of code as a metric... > overall the new proposal has less than 50 lines of code that are relevant (I > don't know the number for upstream, but I think it's safe to say it's more). > If we assume that we can achieve the same results with less code then I think > the answer is easy here > maintainability: well, see above... the current solution is not documented at > all and I am pretty sure I am not alone when I saw "I really can't explain > all the steps" (doesn't mean they are not necessary); what I want to say is > that the existing solution would really need a lot more explanation than just > "CQRS", I think that would be a fair requirement. Admittedly, the new > proposal also has no documentation (other than the wiki page and what I wrote > in this message). But: I think if I did write it it can fit on one page (with > diagrams), this module (it's a real one) has (almost) no external > dependencies (other than the frameworks that we use anyway), it makes no > assumption about any of the business logic that might or might be passing > through (existing implementation fails already there... see CommandWrapper > and the various entity IDs that are buried there... this wrapper class should > not be aware of anything it transports)... which brings me back to the point > of less code which is I think from a maintenance point of view preferrable JD: When I say "overly clever" that is in contrast to simplicity through elegant design. A favorite quote "There are two ways of constructing a software design: One way is to make it so simple that there are obviously no deficiencies, and the other way is to make it so complicated that there are no obvious deficiencies. The first method is far more difficult." I think if you are aiming for something simple enough to have obviously no (or much fewer) deficiencies, that is, an improvement. But, could you write some documentation about the concept? It should be simple to describe "on paper", yes? > > Apache Camel: ... disclaimer, I really like that framework and used it on a > ton of occasions. That being said: choosing a framework is a commitment > pretty much like a vendor lock-in. Depending on how you integrate a framework > like Camel (this will be more than a JAR file and you can either hide the > fact you use Camel from the rest of your app or you fully expose it...) > upstream means if for some reason it turns out that Camel is not a good > choice or the community doesn't want yet another dependency then we might > find ourselves in a refactoring fest to revert things. If you look closely in > the proposed sources you will see that first of all there are Java interfaces > that propose a contract on how to wire things together... and there not > many... which leaves a lot of room for actual implementations (Camel or > something else). In fact, 3 or 4 years ago I actually created a drop-in > replacement for the upstream SynchronousCommandProcessing service and ran > Camel behind the scenes and was actually very happey with the outcome. When I > did this there were basically 2 relevant functions that needed to be taken > care of. Today there is a lot more going on there and I am not so sure if you > could just drop-in Camel effortlessly with the current incarnation of the > command processing service. JD: Ok. I can buy not wanting another dependency, but only if our level of effort is relatively small ongoing. Otherwise we are taking on code maintenance for our "own thing" when a perfectly suited solution is in the same software foundation. > Asking Apache Camel's community for opinion: well, can't hurt... they do > stuff like this literally every day, so I am pretty sure whatever we'll > exchange with them will be very informative. But that doesn't relieve us from > deciding if you want to go all in on Apache Camel it would be anyway a good > practice to abstract these implementation details away (aka hide to the rest > of Fineract that you are using Camel). If that is the case then we need a > contract (aka Java interface). The one that is there won't do it anymore... > without major rework... and that is the point. The proposal intends to ensure > a gradual non disruptive migration (not open heart surgery) JD: Sure, that makes sense, you need to new Java interface... but wouldn't it be better to spend a bit of time in design and validation at this early stage. I think we're talking about a pretty significant optimization from its location in the stack. Who should reach out? > whitepapers, alternatives: I think the first thing that Google or ChatGPT > searches will tell you is "use an existing CQRS framework"... and this will > most likely show you AxonIQ (a CQRS framework implemented with > Spring/Boot)... but that is then even more of a vendor lock in than using a > more generic solution like Camel... Axon will force us to use their contracts > (internal APIs, Java interfaces etc.), in short: refactor fest, disruptive. > There are other low level "solutions" (like LMAX Disruptor) that are somewhat > in the vicinity of this type of application, but require work, to my > knowledge there is nothing out there we could just magically drop and use > without any refactoring. Disclaimer: in one of the 3 drop-in implementations > of the proposed command processing I am actually using LMAX Disruptor... its > implementation details just don't leak into the rest of the system > Spring Boot 3 compliance: yes (buzzword drop: "auto-configuration") JD: Excellent > cutting edge: not sure how to read this here... is this meant as a > requirement or as an argument against the adoption of the proposal as in "too > experimental"... as I've written the code I am obviously biased so I leave > that to the community to decide and come up with improvements and/or > alternatives/arguments if someone doesn't agree JD: Yep. The ambiguity is on purpose - cutting edge can be great in getting results, or it can make you bleed. > > Let me know if I skipped something, made an error or was not clear enough. JD: Very clear. Now, before this code is committed, I would also like to be sure we have a sensible way of documenting the progress so that if we are doing a release, we make note of how much of the code base is using the new methods. I also think we should discuss this in context of the next release. (coming up soon). > > On Thu, Jan 23, 2025 at 5:00 PM <jdai...@apache.org> wrote: >> >> Thanks for bringing this to the list. It looks to be a very low level (in >> the stack) and therefore, highly impactful. I was there when the decision >> was made to adopt this pattern and SynchronousCommandProcessingService as a >> flexible improvement to the existing CQRS. I remember asking some questions, >> but this was and is, beyond my direct experience. >> >> >> https://cwiki.apache.org/confluence/display/FINERACT/FSIP-5:+New+command+processing+infrastructure >> >> What I do know is that we should be deliberate with this process, and I >> appreciate your write up on wiki. Definitely other architects here should >> take a look. >> >> At times over the past decisions - it feels to me that we try to be "too >> clever", and this creates a problem with maintainability. I'd like to make >> sure we understand the alternatives as we dig into this. You raised Apache >> Camel as an option - would it be worth it to ask someone over in that >> project to comment on this? Is there some whitepaper or comparison out >> there between the alternatives available? Is this consistent with Spring >> Boot 3 ? Is this on the cutting edge?
