UDP Multicast in Silverlight 4

In Silverlight 4, we have added multicast support. If you’re not familiar with multicast, here’s a quick scenario to explain what it is and why it might be useful to you. Scenario Overview Suppose your company provides market data and you need to distribute the same commodity and value records to 50,000 client workstations. It…

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New Performance Counters for HttpWebRequest

Performance counters!  You can never get enough!  And starting with the .NET version 4.0 Beta 2, we in the System.Net team have added six new counters to the old set.  But before we begin, some ground rules: Performance counters have to be enabled in your application’s .config file.  I’ve put a sample of my config…


What’s new in System.Net.Mail

What’s new in System.Net.Mail We’ve made a number of enhancements to our SMTP support for .NET 4.0, mostly in the area of Unicode support and increased standards compliance, which is an important aspect in ensuring that legitimate emails do not get flagged as spam, as well as a few other useful features.  In this post…

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End-to-end connectivity with NAT traversal

Like street numbers for a house, the Internet was originally designed so that all network devices could be directly addressed. Every connected device was given at least one unique identifier, or IP address, which could be used to route network packets to and from the device. For a while this worked well and devices had…

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New NCL Features in .NET 4.0 Beta 2

We’re introducing some new features starting with .NET 4.0 Beta 2 that you may find useful. Additional information will be available on MSDN and in subsequent articles. If you have any questions or comments, let us know! Sockets DnsEndPoint This feature was first introduced in Silverlight 2 and it allows you to connect to a…

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Why does Silverlight have a restricted port range for Sockets?

Silverlight restricts the ports of outgoing TCP socket connections to the range 4502 – 4534. Connecting to a different port requires the use of a server-side proxy or port redirector. One of the most common questions we hear from customers about this is, “Why do you restrict the port range in Silverlight? It doesn’t add…

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Custom HTTP Authentication Schemes

Introduction           My name is Chris Ross and I work as a developer for Microsoft’s .NET Framework networking components.  As part of the Network Class Library (NCL) team I get lots of networking questions from other developers.  This post resulted from my research into a question about using custom HTTP authentication schemes.  The custom scheme in…

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Functional Areas of the Network Class Library

If you are wondering exactly what is in the NCL, the diagram below should help. It’s a high-level roadmap of the key feature areas and components. As you can see, the NCL is a roll up of the System.Net.* namespaces and the URI related classes in System. Networking features include sockets, an HTTP client, an…

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Code Patterns for Online/Offline Network Detection

In the last entry I showed you why you should use the NetworkChange.NetworkAddressChanged API to control when to check if your application is online or not.  If you didn’t read that article, go do it now – it will help you understand why online detection is hard, and why the network detection code is made the…


Online/Offline Network Detection with the .NET Framework

Imagine this: you have been working on your great New World Wide Web program.  Your very first customer tries it out on their new notebook computer — perhaps one of those very cute tiny notebooks that people are buying everywhere.  And then you get your first report back: “I tried it while walking down the…