Udi Dahan - The Software Simplist

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Articles: 1, 2, 3, 4, 5, 6, 7

Durable Messaging Dilemmas
2008-07-17 17:18:00
I’ve received some great feedback on my MSDN article and some really great questions that I think more people are wondering about, so I think I’ll try to do a post per question and see how that goes. Libor asks: “Would you recommend using durable messaging for systems where there are similar requirements with respect to data ...
More About: Architecture , Performance , Scalability , Availability , Durable

Mobile.UdiDahan.com
2008-07-15 09:09:00
It’s that simple to get my feed straight to your mobile.
More About: Mobile , General

MSDN Magazine Article On Losing Data
2008-07-07 08:58:00
Now I can die happy. I’ve made the cover of the latest issue of MSDN magazine. OK, enough of that. I really am thrilled that Microsoft has taken a non-technological article and promoted it in such a way. Change is happening, and I like it. With a name as long as most of my variables, this article ...
More About: Articles , Magazine , Article , Data

Make WCF and WF as Scalable and Robust as NServiceBus
2008-06-30 14:47:00
This topic is getting more play as more people are using WCF and WF in real-world scenarios, so I thought I’d pull the things that I’ve been watching in this space together: Reliability Locking in SqlWorkflow PersistenceService (via Ron Jacobs) where, if you want predictable persistence (MS: ‘none of our customers asked for this to be easy’), ...
More About: Testing , Scalability , Make

Object Relational Mapping Sucks!
2008-06-25 06:32:00
For reporting, that is. And doesn’t handle concurrency! Unless you don’t expose setters. I guess it depends, doesn’t it? Well, that was Ted’s assertion in his recent Pragmatic Architecture column on data access. But, “it depends” doesn’t get the system built, does it? So, here are some rules for using o/r mapping that will get you 99% of the ...
More About: Business Rules , Scalability , Object , Sucks

Sagas Solve Stupid Transaction Timeouts
2008-06-23 02:09:00
It turns out that there was a subtle, yet dangerous problem in the use of System.Transactions - a transaction could timeout, rollback, and the connection bound to that transaction could still change data in the database. Think about that a second. Scary, isn’t it? At TechEd Israel I had a discussion with Manu on this very ...
More About: Service , Scalability , Stupid , Workflow , Databases

[Podcast] Highly Scalable Web Architectures
2008-06-19 15:42:00
For those people who couldn’t come to TechEd USA and didn’t see my talks on how to build highly scalable web architectures, you’re in luck - Craig, the man behind the Polymorphic Podcast sat down with me and we chatted about what the problems, common solutions, and effective tactics there are in this space. For ...
More About: Architecture , Caching , Scalability , Web Services

External Value Configuration with IoC
2008-06-13 11:32:00
One of the things I haven’t like about using IoC containers, AKA dependency injection frameworks, was the string-based configuration model they exposed. In order to set these values, developers had 2 options: either use XML config (usually without the benefit of intellisense or refactoring support), or use code (still quoting property names - again, no ...
More About: Development , Simplicity , Dependency Injection , Configuration , External

Prism - Occasionally Connected?
2008-06-09 14:46:00
Prism, AKA Composite Application Guidance + Composite Application Library, is rolling towards a release. I’ve been talking with Glenn Block quite a bit about Prism, and am even on the advisory board (what were they thinking?). One of the topics not covered by Prism is occasional connectivity, and I would like to say a word or ...
More About: Architecture , Development , Threading , Prism , Connected

Web Scalability Slides and Code
2008-06-06 14:23:00
For all the people who came to my talk on Web Scalability with Asynchronous Systems Architecture, thanks for coming and being such a great audience. For all my other readers and loyal subscribers, I’ve updated the code since last it was published so you can find the new stuff here. Here’s the powerpoint And here’s the code
More About: Code , Slides

Architecture & Design World 2008
2008-05-31 13:23:00
In the vein of my previous post, I’ll be coming back to the States a month after TechEd for Dr. Dobb’s Architecture & Design World 2008. I’ll be giving my Avoid a Failed SOA talk (again). Apparently, I’m not the only one who’s been seeing one SOA project fail after another. Luckily, I’ve lived through enough ...
More About: Service , Presentations

TechEd USA 2008
2008-05-31 12:56:00
I’ll be flying to Orlando FL in the next couple of days to TechEd USA. I’ll be speaking about how to create high performance and scalable web applications based on the principles I outlined in my previous post Asynchronous, High Performance Login for Web Farms. I’ll also be giving a more interactive session on How ...
More About: Presentations , 2008

NServiceBus Performance
2008-05-21 09:08:00
I’ve gotten this question several times already but now companies are beginning to look for performance comparisons in making decisions around the use of nServiceBus. It’s often compared to straight WCF, BizTalk, and now Neuron ESB. In Sam’s recent post he posts to a case study of Neuron doing 28 million messages an hour. That’s far more than I’ve ever heard quoted for BizTalk. Disclaimer Before giving some numbers, please keep in mind that high performance of system infrastructure does not necessarily by itself mean that the system above it is running that fast. For instance, you may have server heartbeats running really quickly but the time it takes to save a purchase order borders on a minute. So, please, take all benchmarks with a grain of salt, or two, or a whole shaker-full. While I’m not at liberty to say on which specific domain/company these numbers were measured, I can say that we had the full gamut of “stateless services”, s...
More About: Performance

7 Simple Questions for Service Selection
2008-05-17 00:21:00
“So, which services do I need?” This innocuous question comes up a lot. Usually I get this question after a short problem domain description. One of these came up on the nService Bus discussion groups. Ayende took it and ran with it turning it into a nice blog post, An exercise in designing SOA systems. I’ve been ...
More About: Questions , Simple , Selection

The Abbott & Costello of SOA
2008-05-03 00:37:00
My long-time readers will no doubt remember Bill, he who has sent me so many great questions around SOA and gotten me to put some of my best podcast episodes out. Well, Bill’s now got a blog and he’s putting up a lot of great information on SOA (and that’s saying quite a bit, I ...
More About: Abbott

[Video] Messaging and Architecture Discussion at ALT.NET
2008-04-28 23:53:00
In this video, Greg Young, Martin Fowler, Evan Hoff, Dru Sellers, myself and some others discussed various aspects of event-based systems, how Domain-Driven Design works with them, what role messaging has, and how all these connect to architectural properties like scalability and fault tolerance. One of the questions that Martin started answering was how teams can ...
More About: Video , Architecture , Scalability , Discussion

Visual Cobol, Enterprise Processes, and SOA
2008-04-23 17:15:00
There’s a fairly intense discussion going on these days amongst the SOA illuminati. In the hopes that people will see me standing beside them and conclude that I too know something, I’ve decided to chip in. Jim brought the concept of cohesion to the regular SOA discussions around loose coupling in his post Anemic Service Model, ...
More About: Visual , Cobol , Enterprise , Processes

Twitter
2008-04-20 20:04:00
After seeing everybody twittering at both the MVP summit and the ALT.NET conference, I’ve decided to take the plunge. Not quite sure what to expect, but here goes.
More About: Community , Twitter

Time Dimension Necessary For Successful SOA Data Strategy
2008-04-20 18:49:00
I often run into companies working on an SOA initiative where certain information aspects are given more importance than is warranted and, as a result, the overall service coupling is increased. Sometimes this takes the form of a Canonical Data Model or as a Master Data Management service. In both cases, information is divorced from ...
More About: Architecture , Strategy , Time , Dimension

WCF, Smart Clients, and Deadlocks
2008-04-11 11:15:00
There’s a new article up on MSDN describing how to write Smart Clients using WCF. The author is none other than WCF-Master Lowy and he goes over the multitude of ways you can deadlock yourself. Here’s a taste: UI Thread and Concurrency Management Whenever you use hosting on the UI thread, deadlocks are possible. For example, the following ...
More About: Architecture , Development , Service

Scalability Article up on InfoQ
2008-04-11 07:59:00
I’ve published a new article on performance and scalability on InfoQ: Spectacular Scalability with Smart Service Contracts In this article, I attempt to debunk some of the myths around stateless-ness as the key to scalability. Here’s how it starts: It was a sunny day in June 2005 and our spirits were high as we watched the new ordering system ...
More About: Articles , Architecture , Performance , Article

TechEd Israel Wrap Up
2008-04-09 17:50:00
To all the people who came to see my talks at TechEd Israel , I just wanted to thank you for being such a great audience and asking insightful questions. You can find the slides here: Designing High Performance Persistent Domain Models Avoid a Failed SOA It was a bit unfortunate that video wasn’t recorded for these talks, however ...
More About: Presentations , Wrap

NServiceBus Explanations
2008-03-30 13:36:00
Ayende’s been going over nService Bus, seeing how it’s built, and raising various questions and concerns. I’ll begin by taking them from the outside, in - that is, first API questions, and then internal structure issues. SendLocal First of all, the effect of calling SendLocal on IBus takes all the logical messages passed in (params IMessage[] messages), wraps ...
More About: Architecture

NServiceBus Explanations
2008-03-30 13:24:00
Ayende’s been going over nServiceBus, seeing how it’s built, and raising various questions and concerns. I’ll begin by taking them from the outside, in - that is, first API questions, and then internal structure issues. SendLocal First of all, the effect of calling SendLocal on IBus takes all the logical messages passed in (params IMessage[] messages), wraps ...

NServiceBus Explanations
2008-03-30 13:23:00
Ayende’s been going over nServiceBus, seeing how it’s built, and raising various questions and concerns. I’ll begin by taking them from the outside, in - that is, first API questions, and then internal structure issues. SendLocal First of all, the effect of calling SendLocal on IBus takes all the logical messages passed in (params IMessage[] messages), wraps ...

Judgement and Experience
2008-03-30 11:16:00
[Filed under quotable quotes] Good judgement comes from experience, and experience comes from bad judgement - if you survive it. [Source]
More About: Experience , Judgement

I Hate WSDL
2008-03-28 17:44:00
Ted says it really well, and let me add a big +1. Note to those who didn’t attend the session: you didn’t hear me say it, so I’ll repeat it: I hate WSDL almost as much as I hate Las Vegas. Ask me why sometime, or if I get enough of a critical mass of questions, ...
More About: Architecture , Service , Hate , Web Services

SOA Training Videos and Pricing
2008-03-24 11:15:00
It looks like the SOA training videos will start coming in the next week or so. So, I’ve started thinking what else should be included so that you get the most out of them. Here’s what I’ve currently got in mind: All the powerpoint presentations Full source and samples of nService Bus so you can run the code as ...
More About: Videos , Training

QCon London 2008 Recap
2008-03-20 10:07:00
Well QCon was a blast. NService Bus Tutorial I gave a full day tutorial on nServiceBus and we had a full house! The tutorial was about 90% how to think about distributed systems, and 10% mapping those concepts onto nServiceBus. I made an effort to cram about 3 days of a 5 day training course I give clients ...
More About: London , Presentations , Recap , Web Services

Sundblad Mistaken on Services
2008-03-16 14:29:00
The brilliant guys at 2xSundbland have launched their architect academy and it looks quite promising. I haven’t yet taken the trial lesson, but its in the queue. I have taken a look at the articles they have on the site as well, and they’re quite good. I especially like the Software Architecture vs. Software Engineering ...
More About: Services