The Moth

In a previous post I showed where we find the assemblies that make up the Silverlight 2 Beta 1 framework. Have a quick glance at the screenshots to remind yourself. Below, I follow up on the promise in my closing sentence of that blog entry.

1. mscorlib.dll includes almost 30(!) public namespaces, which means it is missing only about 20 namespaces compared to the desktop full version. Of course, even when the namespace exists in both versions of mscrolib, there are some types missing from the Silverlight version. In general terms the omissions are to do with: hosting, remoting, registry access, non-generic collections, serialization and some of the security types that are Windows-specific (e.g. System.Security.Principal/Policy/Permissions/AccessControl namespaces). We also find some types having members missing (e.g. the GC class does not have overloads of Collect that accept the generation to collect, no ThreadPriority etc) but nothing major. On the flip side, Silverlight adds some new sporadic members of its own e.g. a new NoOptimization value to the MethodImplOptions enum, and new attribute classes such as System.Security.SecuritySafeCriticalAttribute and System.Runtime.InteropServices.AllowReversePInvokeCallsAttribute. Generally speaking, there are tons of stuff in this assembly, the largest of them all in the Silverlight framework, so please explore on your own the compatible subset.

2. System.dll has just 6 public namespaces so it is 30 short of its desktop brother (but we'll see later that some of those are available in other Silverlight assemblies). The things truly missing though make sense such as: CodeDom, the specialized and generic collections (except for Queue and Stack which are present), configuration classes for reading appsettings, performance counters, tracing (but a thinner Debug class is present), EventLogging and SerialPort support. Whilst support for regular expressions is there, you cannot CompileToAssembly.

3. System.Xml.dll is missing the entire Xsl and XPath namespaces and even the support it has for Schema and Serialization is minimal at best (a total of 1 concrete class, 1 interface and 1 enumeration!). The main namespace (System.Xml) is almost fully implemented though with some additions as well (e.g. XmlXapResolver class and DtdProcessing enum) and notable omissions the Text reading/writing and the DOM model (XmlDocument and relatives).

4. System.Net.dll is a bit weird. You see, on the full framework there was a System.Net.dll introduced with .NET Framework v3.5 that had all the P2P stuff. However, the assembly here in the Silverlight framework has absolutely nothing to do with any of that! Instead, this assembly is all about sockets. On the full framework the implementation of sockets has always lived in System.dll (which we saw further up), so not sure why the factored out the 2 namespaces (System.Net and System.Net.Sockets) into this one. Maybe it is because, not only there are many types and methods missing, but also there has been some "butchering" that renders many things incompatible with each other (such as changing concrete classes/methods to be abstract, changing the type returned from various methods and adding new members to various places). The principles are the same though and, in a nutshell, you can connect back to your server asynchronously via sockets (but you cannot listen/accept).


Next time we'll see the Silverlight assemblies that stem from v3.0/v3.5 desktop counterparts.