Series Introduction # I initially was going to put this together as a single post but quickly realized that it would be a bit much to try and put all of the information into one post. To make it more digestable, I decided to break it up into separate parts. This is by no means a comprehensive study of lambda calculus or type theory, but rather a quick introductory series so you can can get started. My goal is that, by the end, you will be able to understand enough to start reading papers on your own and have some cursory knowledge of type systems. Also, I am targeting programmers that want to get a better understanding of the theory behind type systems in compiler design. If you are comfortable programming in functional languages, then you will start to see many parallels quickly. Although, I will give examples using an imperative approach to cover programmers who may not immediately appreciate these parallels.
Introduction & Scope # The PCAP-NG file format is used to store network captured data used by great programs like Wireshark. There are several API's available for both Linux and Windows but none that are ported to .NET. I decided to make one for my own use in building a network traffic replay agent.
Introduction & Scope # When developing a new web service, you may need to do an initial spot test walk through the operations or try to break the service based on the permissible data type values. You could hand craft all the operations, with their respective arguments, into a handful of URLs but that would seem pretty inefficient. I found myself in a similar situation and wanted a programmatic way to walk through the service operations with a specific input data set. To be clear, I am not attempting to recreate a full web service testing application but rather a simple script to spot check responses and catch any bugs in a web service endpoint's handler.
Introduction # If you are already familiar with finite automata, then understanding a Markov chain will not be as hard. If you are not familiar with one, you can think of finite automata as a flowchart, with states and paths leading from one state to another based on some decision being made. An example could be a room with a light switch; there are the two states of having the light on or off. Using the light switch will transition you between the two states.
Introduction # In some cases, you may want to read/write binary data from/to your relational database. This can be a problem when the data set size exceeds the memory address size (eg. 32-bit processes) or the managed large object heap cannot load it all without throwing an OutOfMemoryException. In those cases, you will need to load the data into memory in chunks. Fortunately, the T-SQL syntax supports this operation.
Definitions # In a lot of texts regarding compression you will run across various conventions of syntax to describe the coding of data. Much of them are used in fields like automata theory, group theory and statistics. Although, the field of coding theory itself has a long and rich history in the 20st century; much of the terminology is borrowed from fields that gave rise to it.
Introduction # Microsoft introduced native image mastering support in Vista, going forward. The library itself is not too complex but the latest version of the image mastering API (IMAPI) has some quirks. This is well documented by Eric Haddan in his article describing how to build an interop file and use it from .NET.
Introduction # I was working on implementing a simple compression tool based on naive Huffman coding and initially assumed all of my prefix codes would be at or under a byte long. Although I failed to account for the worst case of Huffman coding, which can yield codes up to 255 bits in length.
Motivation # One of the main concerns in any licensing implementation is that authored license files are coming from the trusted authority (ie. your company) and not some third party. This can be accomplished in software by encrypting and decrypting the license with a single key, but symmetric key storage can be cumbersome and have added complexity.
Background # There are plenty of sites that will tell you how to enable IIS through the Control Panel. Although, if you are tasked with enabling IIS automatically (eg. for an installer), it can be a nightmare. This is only really needed though in special cases where the installer has more control over the hardware specifications. Determining an upgrade or uninstall scenario with IIS can be very tough since you are not installing your own software but rather enabling a feature of Windows. With that in mind, we can propose a solution for automated enabling of IIS.
Background # Unlike most sensors used in data acquisition, thermocouples do not have a linear mapping between their voltage and celcius values. This means that instead of factoring some scalar value against the data, in order to scale it to engineering units (eg. volts to acceleration), an experimentally derived equation must be created to approximate the temperature at specific voltages. This non-linearity is primarily due to the materials being used to discover the temperature difference.
Using Conditioned Tags # The Visual Studio 2010 UI does not have options to handle conditional references based on what kind of configuration and platform you are running. For example, you may have a project reference that needs to change depending on whether you are doing a 32 or 64 bit build.
WPF & Multithreading # In designing applications, it may be advantageous to run data processing methods on a separate thread from the UI. This allows greater responsiveness in the application and takes advantage of concurrent computation.
While Java may be a higher level language that makes code writeability easier, conventions must be broken when developing on Android to reap performance gains. This is especially true for games where logic and rendering must be done on a tight loop.
A POCO (Plain Old CLR Object) must be transformed into a POCO proxy
[MyNamespace.MyClass ->{System.Data.Entity.DynamicProxies.MyClass_0A943C2FC37D33304CEB497A9210C754E3F553B50315F8E6F0F7A6FAF43777F2}]{.Apple-style-span style=“font-size: x-small;”})
in order for features like lazy loading and change tracking to work.
MSDN has a great article that explains how to prepare a POCO to be transformed into a proxy. If you find that an object retrieved or attached to the context does not show itself in the DynamicProxies namespace (eg. MyNamespace.MyClass instead of ...DynamicProxies.MyClass), then you probably don't have a compliant class. You may have noticed this already when hovering your mouse cursor over an instance and seeing the runtime information on it.
The distilled points are that your POCO must:
I was recently working on solving problem 64 for project Euler and one of the needed algorithms was a detection of cycles in a list. This routine works for detecting cycles in lists of cardinality greater than 2.
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I recently installed the Entity Framework June 2011 CTP to preview the enum support but ran into a bug along the way that reported an error while processing the template.
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I just started using the Entity Framework recently to employ persistence for an already established code base. Initially I was using the "Model & Database First" paradigm where a designer is used to layout the data model. Although, this ended up being tedious since my POCO instance had to exactly match the POCO proxy instance in my model designer view. After upgrading to EF 4.1, I realized the "Code First" paradigm was the way to go since I had to adapt the persistence model to my already existing code.
One of the earliest problems that I ran into was having more than one property on a class that referenced the same class type. This example was taken from a great site that explored the different EF properties.
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I have been working on a game where enemy characters must select a target seemingly at random but such that the distribution of selected targets is balanced. Initially I had come up with a randomization algorithm with weighted values for each target but this became cumbersome and much too complex.
Then I remembered the scheduling algorithms from my Operating Systems class. In particular, the lottery scheduling algorithm.
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I was tasked recently with writing a parser for TEDS bit stream data. There is an IEEE published paper with an overview of the standard but it doesn't give any examples for implementation. I was finally able to find a paper that gave examples but still had trouble parsing the data. I finally realized there is not only 2 selector bits after the basic TEDS block but selector bits inside the standard template (2 in the case of template 25). Here are my main findings:
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