MSDN Magazine - April 2008 - (Page 50)

Instantly Search Terabytes of Text N dozens of indexed, unindexed, fielded data and full-text search options (including Unicode support for hundreds of international languages) N file parsers / converters for hit-highlighted display of all popular file types N Spider supports static and dynamic web data; highlights hits while displaying links, formatting and images intact New .NET Spider API h Spider Desktop wit h Spider Network wit CD/DVDs Publish for pider Web with S Win & .NET Engine for Linux Engine for New 64-bit N API supports .NET, C++, Java, databases, etc. The Smart Choice for Text Retrieval® since 1991 N “Bottom line: dtSearch manages a terabyte of text in a single index and returns results in less than a second” – InfoWorld N “For combing through large amounts of data,” dtSearch “leads the market” – Network Computing N dtSearch “covers all data sources powerful Web-based engines” – eWEEK N dtSearch “searches at blazing speeds” – Computer Reseller News Test Center See www.dtsearch.com for hundreds more reviews, and hundreds of developer case studies Contact dtSearch for fully-functional evaluations 50 msdnmagazine Foundations 1-800-IT-FINDS • www.dtsearch.com when opening and closing its channel—but not when actually using it. The interesting effect of structuring the proxy this way is that now the client code will be subjected to the raw WCF security demands—that is, all the security demands required to marshal the call to the service! For example, if the proxy is using the TCP binding, the proxy will first demand the client permission to execute (all managed code requires that permission). Second, the proxy will demand that the client have permission to connect to the required port on the service machine, and unrestricted DNS permissions (required to resolve the host’s address). Third, there are some collateral permission demands unrelated to the use of TCP, pertaining to the context of the call. If the client wishes to use Windows security and send the user’s interactive identity, then the proxy will demand environment permission access to the USERNAME variable. If the client wishes to send alternative Windows credentials, then the proxy will demand security permission to control the principal. If the client wants to dispatch the call asynchronously or receive duplex callbacks, then the proxy will demand permissions to control the policy and the evidence (both are flags of the security permission, required when bouncing calls between threads). If the client wishes to use reliable messaging, then the proxy will demand policy control as well. If the client uses message security with user-name credentials, with service certificate negotiation and without validating the negotiated service certificate, then the proxy will also demand permission to control the policy and the evidence. If the client utilizes the WCF diagnostics and tracing facility, then the proxy will demand access to the COMPUTERNAME environment variable (to be able to trace it) and unmanaged code access (presumably to access the log files, so it should have been a file I/O permission instead). Finally, the proxy will also demand of the client permission to execute unmanaged code. Unmanaged code access is a highly privileged security permission, granted only to the most trustworthy code. Granting unmanaged code access permission can amount to disabling CAS since unmanaged code is exempted from CAS. Classes and frameworks designed to work in a partial trust environment should never demand unmanaged code access (even if they use interop) and instead demand a more narrow permission describing the nature of the unmanaged operation performed. The TCP channel demands unmanaged code simply because its original design did not take into account partially trusted clients. Then there are certain WCF capabilities that bluntly resort to full trust demands, even though there are perfectly matching permissions types. Any attempt to propagate a transaction requires full trust (instead using the distributed transaction permission) and any access of a certificate store requires full trust (instead of using the certificate store permission). Figure 3 shows the raw WCF security demands invoked by code such as my last revision of PartialTrustClientBase , when the bindings are set to their default settings, for a few key scenarios such as transactions, reliability, diagnostics, asynchronous calls, certificate store access, and message security. The only bindings that do not demand unmanaged code access http://www.dtsearch.com http://www.dtsearch.com http://www.dtsearch.com

Table of Contents Feed for the Digital Edition of MSDN Magazine - April 2008

MSDN Magazine - April 2008 Contents Toolbox CLR Inside Out Basic Instincts Cutting Edge Foundations Test Run Service Station Windows with C++ Going Places { End Bracket }

MSDN Magazine - April 2008

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