I'm working on this system that allows the user to perform certain tasks on a map. For instance, building a route on the map is performed by quite simply clicking on the map to add waypoints. This action is done as a part of the RouteForm data entry - on the form there is a button that, when clicked, changes the map's state to accept user input...

I ran into this post a couple of days ago on InfoQ which described some kind of product/technology that would enable a system to perform "high volume event correlation". These happen to be the kind of systems that I work on. For some reason, the company behind this product thinks that databases don't support these non-functional requirements...

Today I got an email from Peter, a listener of my podcast with the subject "REST vs Web Services mp3 discussion - Thanks!". "Hello Mr. Dahan, I just wanted to let you know that I found your discussion on REST vs. Web services very interesting. Two years ago, I got to learn about Web services and WSDL, in order to figure out if I can use that to...

The C# compiler doesn't like the following code: public void NewCommandActivatedCallback(object sender, EntityTypeEventArgs e); { switch(e.EntityType) { case typeof(Customer): // open new customer form; break; case typeof(Order): // open new order form; break; //and so on } } It doesn't like the fact that the values of the case elements aren't...

I had a discussion the other day with an architect who is just starting out. He asked me what makes an architect effective. After giving it some thought, this is what I answered. The difference between an effective architect and one who isn't is that the architecture/design/technology guidance that the effective architect prescribes is...

Get it here. This week we brave the flames of the ongoing REST vs. Web Services debate. REST, or REpresentational State Transfer, is an architectural style founded on the simplicity of HTTP, while Web Services are, in essence, a set of specifications supported by several vendors in various phases of standardization. Join us for an examination...

I just read this blog post on "How SOA helps you hit the agile sweet spot" by Steve Jones and wanted to add a couple of points. Martin Fowler also wrote about this in his Application Database pattern. Steve says: "1. When you are doing a project, work out what the services are upfront.  2. Clearly define the interactions between these...

Via TheServerSide.Net, Microsoft Research Distinguished Engineer Butler Lampson session on ‘Failures and Futures in System Research’ points out that to succeed, systems must be able to gracefully fail. He continues with the failure of RPC in that the architecture places too many requirements on widely scattered nodes that must continually...

In the comments on my previous blog post, Reliable Messaging, Transactions, and Messages – oh my!, my fellow DDJ blogger - Eric Bruno made a number of points that I think are pertinent, and to which I wanted to respond. "I would go even further and say that all messages need to be reliable. Even a missed stock update can result in lost money...

In the comments on my previous blog post, Reliable Messaging, Transactions, and Messages – oh my!, my fellow DDJ blogger - Eric Bruno made a number of points that I think are pertinent, and to which I wanted to respond. "I would go even further and say that all messages need to be reliable. Even a missed stock update can result in lost money...

In the comments on my previous blog post, Reliable Messaging, Transactions, and Messages – oh my!, my fellow DDJ blogger - Eric Bruno made a number of points that I think are pertinent, and to which I wanted to respond. "I would go even further and say that all messages need to be reliable. Even a missed stock update can result in lost money...

Issue 8 of the Microsoft Architecture Journal is out, download it here. In it you can find my article on Autonomous Services & Enterprise Entity Aggregation: Enterprises today depend on heterogeneous systems and applications to function. Each of these systems manages its own data and often doesn’t explicitly expose it for external...

In part 1 of this topic, a different kind of API was presented for asynchronous callbacks. Pretty quick, in the comments, Ralf pointed out the problems with this approach. These problems are very typical in multi-threaded scenarios and manifest as hard to find (and reproduce) bugs. However, in cases where we are performing "highly asynchronous...

In part 1 of this topic, a different kind of API was presented for asynchronous callbacks. Pretty quick, in the comments, Ralf pointed out the problems with this approach. These problems are very typical in multi-threaded scenarios and manifest as hard to find (and reproduce) bugs. However, in cases where we are performing "highly asynchronous...

I have a new 2 day workshop available on SOA. This workshop is available in both on-site and classroom formats. Please contact me at SOA_Workshop@UdiDahan.com for dates and pricing. The syllabus is as follows (download as PDF). Advanced Distributed Systems Design using SOA with Udi Dahan – Israel’s leading specialist on Service Oriented...