If you were interested in algorithms and interested in some mathematical foundations for algorithm analysis? For example if you are interested in proof techniques, probability, Amortization analysis techniques, Case studies and Asymptotic notions (such as Big-Oh, Big-Omega, Little-oh, little-omega, Big-Theta) then check out these lecture notes (in ppt, 224kb) from California State University.
Dec 03 2007
Good UML Tool (and free too)
Love it or hate it UML is important for anyone involved (Architect/Developer/Whoever) – either you need to create designs based on UML and you need to understand that someone else has. Sure it has its challenges and for some specific things there are better solutions (DSL's – more on that some other day). I am "old school" and over the years have used Rational Rose (or whatever IBM has renamed it to since buying Rational out).
But as are aware Rational tools are very pricey and I was on the look out for something reasonable. Most people have heard of EA (no, not the game company) which is a decent tool and not too expensive (at least the Desktop edition).
Of course if you are stingy like me and want something completely free then check out StarUML which is an open source UML/MDA platform and is pretty decent. When you work with it enough you will find some annoying things – most of which has workarounds. There are one or two things it just cannot do, but I only have been using it for a few months now and am quite impressed. Is it better than the likes of EA or Rose, nope but it is pretty damn good for the price.
Sep 20 2007
Rules of Threading
As Mr. Kale so eloquently puts it (and of course 100% correct):
- If you think you need multi-threading, you're wrong
- If your specification says "you need threading", see Rule 1
- (For advanced users only) If you think you need multi-threading, you're probably wrong.
Mar 16 2007
Architect Insight presentations available
I had the opportunity to present on .NET 3.0 in the Enterprise at the Architect Insight Conference hosted by Microsoft earlier this month. All the presentations from the conference are available for download and of course including my presentation (13.6 mb).
Feb 15 2007
Microsoft Architect Insight Conference
Microsoft hosts an annual event in the UK called the Architect Insight Conference. I am one of the speakers this year and will be presenting on “.NET 3.0 in the Enterprise”. This is a pretty good event and I would recommend it if you have not been to one of these. You can check out the Agenda here and if you want, register here and you can find out more information on the Speakers here. Here is a blurb from Microsoft on what can you expect to hear:
You’ll be able to engage in the technology debate with thought-provoking in-depth sessions from customer and partner architects along with members of the UK Microsoft Architect Council such as Avanade, Capgemini, Conchango and Solidsoft.
The agenda is split into seven tracks covering Enterprise, Real World, Identity, Lifecycle, SaaS, Collaboration and Dynamic Systems; the main content sessions will be 75 or 150 minutes in length to accommodate the different formats and levels of interaction that may be required.
There will be an emphasis on architectural ‘investigation’ through the use of small focus groups, as well as a structured networking clinic where individuals from similar vertical business backgrounds can discuss and work through a particular problem domain.
Jun 14 2005
One man's feature is another man's bloat – The Java Performance Debate
Firstly this is not a Java bashing and I don’t preach to say .NET/C++, etc is faster. However, based on what I have seen it sure is slow – slow like a snail. Maybe its the time that takes to load the VM or maybe it Swing – gurk! I like how Andy puts it – “One man’s feature is another man’s bloat”. He has a very objective article on the area which are slow, what Sun is doing to address it and what the main issues (with the developers) are – who don’t know how to use it. He talks about the Memory, JVM, Desktop and Java2D
Jun 02 2005
CLR: Under the Hood
The CLR team has a couple of slides from their roadshow where they talk about two tracks, one discusses what happens insight the CLR, if you have some of the books recommended in the presentation, none of this would be new to you. It covers things like the IL which is the abstract representation of an execution semantic and how that is represented using an abstract stack machine, where we consecutively execute each instruction, using the stack as the evaluation of that execution and how this stack abstraction works. And two, there is a discussion on perf engineering including the GC, costs and pitfalls, etc.
On a different note, been out and about on a few days of holiday with family visiting, but its good to be back now. 
Apr 12 2005
Which encoding is better for webservices?
There are two options when it comes to encoding in the context of webservices, e.g. .NET and Weblogic use document literal encoding while IBM and other vendors (Java) use RPC encoding. What is the difference and which one is better for which scenarios? Also, how easy is it to switch between the two?
Well for those new to webservices, there are two options that you can choose when encoding your wsdl messages.
So, how do they look like. If I “borrow” and example from Sun, if below was your original class in Java:
package com.examples.xmlstring;
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface IStringService extends Remote {
public String sayXMLHello(String xml)
throws RemoteException;
}
The rpc encoding for that looks like this:
<binding name="IStringServiceBinding" type="tns:IStringService">
<soap:binding transport="http://schemas.xmlsoap.org/soap/http"
style="rpc"/>
<operation name="sayXMLHello">
<soap:operation soapaction=""/>
<input>
<soap:body encodingstyle="http://schemas.xmlsoap.org/soap/encoding/" use="encoded" namespace="http://www.examples.com/wsdl/StringService"/>
</input>
<output>
<soap:body encodingstyle="http://schemas.xmlsoap.org/soap/encoding/" use="encoded" namespace="http://www.examples.com/wsdl/StringService"/>
</output>
</operation>
</binding>
And the document encoding looks like:
<?xml version="1.0" encoding="UTF-8"?>
<env:envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:enc="http://schemas.xmlsoap.org/soap/encoding/"
xmlns:ns0="http://www.examples.com/types">
<env:body>
<ns0:sayxmlhello>
<string_1>Hello World</string_1>
</ns0:sayxmlhello>
</env:body>
</env:envelope>
I think in the end the real thing to keep in perspective is who and what will be consuming this? If your clients are primarily MS-based (COM/.NET) then you are better off with literal encoding, on the other hand if its primarily J2EE client then you are better off with the other one. But, more interestingly if you don’t know (or in other words can be both), then which road to take?
Mar 24 2005
Web Services are not distributed objects
Werner Vogel, CTO of Amazon.com has an article which was published a few months ago where we talks about the misconception of how most people think that web services are distributed objects. Here is an excerpt from the article.
The hype surrounding Web services has generated many common misconceptions about the fundamentals of this emerging technology.
Web services are frequently described as the latest incarnation of distributed object technology. This misconception, perpetuated by people from both industry and academia, seriously limits broader acceptance of the true Web services architecture. Although the architects of many distributed and Internet systems have been vocal about the differences between Web services and distributed objects, dispelling the myth that they are closely related appears difficult.
Many believe that Web services is a distributed systems technology that relies on some form of distributed object technology. Unfortunately, this is not the only common misconception about Web services. In this article, I seek to clarify several widely held beliefs about the technology that are partially or completely wrong.
Fundamental Errors: At the International World Wide Web Conference in May 2003, a smart and gifted Internet architect I will call Peter asked me, “Don’t you think Web services will fail like all the other wide-area distributed object technologies that people have tried to build?” I was baffled. How could someone like Peter still view Web services as distributed object technology? Yet, he is not alone in his stubbornness: many developers, architects, managers, and academics still see Web services as the next episode in a saga that includes Corba, DCOM, and remote method invocation (RMI). Web services are distributed systems technologies, but that is where the common ground ends. The only possible relation is that Web services are now sometimes deployed in areas where distributed object applications have failed in the past. Within the distributed technology world, it is probably more appropriate to associate Web services with messaging technologies because they share a common architectural view, although they address different application types.
Given that Web services are based on XML documents and document exchange, we could say their technological underpinning is document-oriented computing. However, exchanging documents is very different from requesting an object’s instantiation, requesting a method’s invocation on the basis of the specific object instance, receiving that invocation’s result in a response, and releasing the object instance after several such exchanges.
I frequently encounter about a dozen other statements that fall into the same basic category. I hear people say, for example, that “Web services are just remote procedure calls for the Internet,” or “You need HTTP to make Web services work.” Before addressing several of the more common misconceptions, we should define a Web service in its purest form in order to begin with a clear model.
Mar 01 2005
Examination of Data Structures in .NET 2.0
You might have seen this already, if not, MSDN has a six-part article extensively examining the data structures in .NET 2.0 covering the usual suspects and then some not-so-usual unless you have written some compilers such as BST’s, graphs, red-back trees, etc. Quite an interesting read when you have some time.
Jan 29 2005
Enterprise Library
Microsoft released the Enterprise Library based on ACA.NET which our engineering guys here at Avanade, work their butts off! Enterprise Library features new and updated versions of application blocks that were previously available as stand-alone application blocks. All Enterprise Library application blocks have been updated with a particular focus on consistency, extensibility, ease of use, and integration.
The application blocks that comprise the Enterprise Library are the following:
- Caching Application Block. This application block allows developers to incorporate a local cache in their applications.
- Configuration Application Block. This application block allows applications to read and write configuration information.
- Data Access Application Block. This application block allows developers to incorporate standard database functionality in their applications.
- Cryptography Application Block. This application block allows developers to include encryption and hashing functionality in their applications.
- Exception Handling Application Block. This application block allows developers and policy makers to create a consistent strategy for processing exceptions that occur throughout the architectural layers of enterprise applications.
- Logging and Instrumentation Application Block. This application block allows developers to incorporate standard logging and instrumentation functionality in their applications.
- Security Application Block. This application block allows developers to incorporate security functionality in their applications. Applications can use the application block in a variety of situations, such as authenticating and authorising users against a database, retrieving role and profile information, and caching user profile information.
Different applications have different requirements and you will not find that every application block is useful in every application that you build. Before using an application block, you should have a good understanding of your application requirements and of the scenarios that the application block is designed to address.
You can also get some more information on Tom’s blog.
Jan 18 2005
Testing .NET Application Blocks (Version 1.0)
A little while ago while I was one of the industry advisors for the PAG group at Microsoft. One of the last things I did in that capacity was provide input to the the Testing App blocks for MS. Microsoft has finally released this and can be downloaded here.
Testing .NET Application Blocks covers many testing areas that were used during testing and verification of the various application blocks provided by Microsoft’s patterns & practices group, such as functional, globalization, performance, integration, and security. The guide uses code examples, sample test cases, and checklists to demonstrate how to plan and implement each type of test; the guide also recommends tools to use to run the tests. It covers test considerations to be taken into account when customizing these application blocks or integrating them with your own applications.
Because this guide focuses on testing NET application blocks, its scope does not include user interface (UI) testing or database testing. Although the guidance is developed within the context of Microsoft patterns & practices application blocks, it still applies to testing .NET code in general.
[Listening to: Nach Deutschland - The Bourne Supremacy - The Bourne Supremacy (02:40)]
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