them on the their journey with CQRS and along the way discovered confusing The CQRS journey release by patterns & practices provides real world insight. I was on a call recently with the Advisory Board for the Microsoft Patterns & Practices (P&P) CQRS Journey project where they were showing. Project “a CQRS Journey” by Microsoft (). 2 points by federicoponzi 7 github repository, journey.
|Published (Last):||13 December 2012|
|PDF File Size:||19.83 Mb|
|ePub File Size:||14.67 Mb|
|Price:||Free* [*Free Regsitration Required]|
Update — clarification cqts here. The conversation got a bit derailed at that point, and I was asked how I would do it though not quite as politelyultimately leading to my tweeting this:. Anyone want to help me show them how to do it right?
Then, all sorts of other behavior are shoe-horned around those entities and… voila, a working system.
A CQRS Journey – with and without Microsoft
That is no reason to block registration from completing. I understand how people can look at systems like TicketMaster and use that as a model for this system but, once again, the differences in the domain matter. Also, attendees going to a conference together are usually coworkers, not family — there are less qualms about leaving someone behind.
This is already leading us to a model where we should not view a group registration as a single success or failure affair.
This will have an impact on the commands, events, and transactions that flow through our system. In any case where people are reserving something far in advance, there is a high likelihood of cancellations. Similar to how hotels overbook by a certain amount to offset cancellationsour conference might look at doing something similar.
The difference is that in the case of a hotel, the guest will likely just book a room in a different hotel in the case the first hotel was fully booked.
For that jourmey, we want to remember who wanted to come to our conference even when we thought we were full. You see, our best chance of joufney a jojrney that opened up due to a cancellation is by a person who wanted jokrney register before. The traditional developer thinking about systems is rooted in synchronous and sequential processes. That sounds like a pretty fair system, the only thing is that fairness was not a requirement.
While conferences, theaters, and airlines all want to have all seats filled, the difference between the ongoing models of airlines and theaters and the once-a-year model of the conference influence how sales are done. Some companies send a lot of employees to our conference so we want to give them preference in registration. It makes sense to bend over backwards for a large group, but not for a small one. A commitment from a large company tends to mean more than that from a small one.
We may have logic that decides to immediately finalize registration from Boeing and other select customers without waiting until 2 weeks before the event. So when we open registration, we can allow the first N people to bypass our waiting list and get accepted right away hourney still needing to be handled later. At that point, you can start moving new registrations through the waiting list.
The thing is that not all requirements are created equal.
We want to align the main boundaries of our software with the stable business elements. User-defined custom fields used in user-defined custom workflows, all of it appearing in reports with sorting, filtering, and grouping. You might as well give your users Visual Studio. The thing here is that we can see the collaborative nature of the domain quite clearly — multiple actors working in parallel where the decisions of one affect the outcomes of another.
Jouurney thing is that Agile Manifesto never said to intentionally cqqrs your head in the sand with regards to the purpose of the system. It was a push-back against spending months in analysis without anything but documents coming out, but the goal was to jougney a middle ground. Developers will often start arguing what the requirements are without really understanding the domain.
That is, if you allow and chose the problem to be complex. Presumably there are policies around block reservations and automatism for a point in time when excess allocations from the pools free up and are released into the global pool that then satisfies the top of a prioritized wait list.
There might be policies for reserved VIP space, discounts, and all other things. The question was — given your chosen complexity scope, how would you divide that up and how would information flow across and between those aspects of the system. For the problem definition as presented on the call, I would have gone with a simple 2-tier solution — no CQRS, no messaging, and used a Jurney storage that can scale out across multiple machines without requiring sharding Cassandra for example.
I totally agree with your statement: Sure, if you invent requirements that make little sense to the business owner, cqs can bend the architecture any way you want so that you can build the thing YOU want not necessarily what the dqrs owner wanted. Thing is, business requirements evolve. You have to live through the entire duration of a years-long project to see how the house of cards you envisioned up-front falls apart to really appreciate the value of agile and delaying ccqrs until the Crqs responsible moment.
You seem to imply that you have to decide on ALL jouurney features the system will have, up front, before you can make a coding decision.
For this reason kourney mention of them and the subsequent description of the requirements for a movie ticket system rings a bit discordant. Perhaps you should consider replacing the mention of them with a vendor such as MovieTickets, Fandango, or MoviePhone, whose primary business is movie tickets. Otherwise, excellent post, as always. If yes where can we find it? Mail will not be published required.
The conversation got a bit derailed at that point, and I cqrss asked how I would do it though not quite as politelyultimately leading to my tweeting this: We need to get into the nitty-gritty of our problem domain to find out what makes it special.
Not all registration systems are equal I understand how people can look at systems like TicketMaster and use that as a model for this system but, once again, the differences in the domain matter. First-come, first-served — fairness The traditional developer thinking about systems is rooted in synchronous jurney sequential processes.
If you liked this article, you might also like articles in these categories: Bryan Wheeler, Director Platform Development at msnbc. The course profoundly changed our understanding and approach to SOA and distributed systems. Consider some of the evidence: Months later, developers still make allusions to concepts learned in the course nearly every day 2. Beyond the training, we were able to spend some time with Udi discussing issues unique to our business domain.
Because Udi is a rare combination of a big picture thinker and a low level doer, he can quickly hone in on various issues and quickly jokrney good if not startling recommendations to help solve tough technical issues. A man I respect immensely. Over and against a certain 3-layer-application-architecture-blown-out-to- distributed-proportions school of SOA, your writing, steers a far more valuable course.
I met Udi at a conference that we were both speaking at, and immediately recognized his keen insight and razor-sharp intellect. Our shared passion for SOA and the advancement of its practice launched a discussion that lasted into the small hours of the night.
It was evident through that discussion that Udi is one of the most knowledgeable people in the SOA space. It was also clear why — Udi does not settle for mediocrity, and seeks to fully understand or define the logic and principles behind things. Humble yet uncompromising, Udi is a cqrss to interact with. What impresses me about Udi is his deep insight into how to address business problems through sound architecture.
Backed by many years of building mission critical real world distributed systems it is no wonder that Udi is the best at what he does. When customers have deep issues with their system design, I point them Udi’s way. Udi helped Frequentis to design a major subsystem of a large mission critical system with a nationwide deployment based on NServiceBus. It was impressive to see how he took the initial architecture and turned it upside down leading to a very flexible and scalable yet simple system without knowing the details of the business domain.
I highly recommend consulting with Udi when it comes to large scale mission critical systems in any domain. Udi is also an exceptional teacher and can help lead teams to fall into the pit of success.
I would recommend Udi to anyone considering some Architecural guidance and support juorney their next project. No matter if you are facing near deadline deadlock or jokrney the early joudney of your development, if you have a problem Udi is the one who will probably be able to solve it, with his large experience at the industry and his widely horizons of thinkingjourneg is always full of just in place great journeg ideas.
I am honored to have Udi as a colleague and a friend plus having his cell phone on my speed dial. He’s always calibrating what he has to offer with your needs and your experience He has strongly held views I trust Udi to tell me what I need to hear, even if I don’t want to hear it, That’s a rare skill to go along with his command and intelligence.
The development is outsourced to India. SOA is a buzzword used almost for anything today. We identified Udi as the one that can put some sense and order in our minds. We started with a private customized SOA training for the entire team in Iourney.
After that I had several focused jorney regarding our architecture and design. I will summarize it simply as he is the software simplist: We are very happy to have Udi in our project. It has a great benefit.
We feel good and assured with the knowledge and practice he brings. We assimilated nServicebus as the ESB of the project. I highly recommend you to bring Udi into your project. Udi has shown impressive abilities of understanding organizational challenges, and has brought the business perspective into our way cqfs looking at services. cqrw
Command and Query Responsibility Segregation (CQRS) pattern
He has an excellent understanding of the many layers from business at the top to the technical infrstructure at the bottom. He is a great listener, and manages to simplify challenges in a way that is understandable both for developers and CEOs, and all the specialists in between. I think Udi should be a premier choice for a consultant or architect of distributed systems. In order to confirm our decision we invited Udi. After carefully listening for 2 hours he said: No matter whether our former decisions were confirmed or altered, it gave us great confidence to move forward relying on the experience, industry best-practices and time-proven techniques that Udi shared with us.
It was a distinct pleasure and a unique opportunity to learn from someone who is among the best at what he does. The nice thing about Udi is that he is able to explain architectural concepts in terms of practical code-level examples.
I would strongly recommend this course to anyone with an interest in how to develop IT systems which provide immediate and future fitness for purpose.