asp.net - Microsoft.Bcl.Build What is it used for -

i tried download , build dotnetopenauth.samples github. got error nuget.targets said the process cannot access file 'xxx\tools\microsoft.bcl.build.tasks.dll' because being used process.

so checked in targets file. found <restorecommand>$(nugetcommand) install "$(packagesconfig)" -source "$(packagesources)" -o "$(packagesdir)"</restorecommand> caused error.

in packages.config found <package id="microsoft.bcl.build" version="1.0.8" targetframework="net40" /> defined.

since found project doesn't reference dll. comment package configuration. , rebuild it. error gone.

but problem why package not being referenced in project while defined in package configuration? (microsoft.bcl.build) used for?

thanks.

updated

forgot add information nuget.

this package provides build infrastructure components projects referencing specific microsoft packages can build.

do not directly reference packages unless receive build warning instructs add reference.

still can not understand yet..

in nutshell, it's helper layer nuget packages. announcement of microsoft.bcl.build 1.0 provides details:

the new version of microsoft.bcl.build ensure solutions containing our packages load if packages aren’t restored yet. affects .net nuget packages depend on it, such microsoft.net.http, microsoft.bcl, , microsoft.bcl.async.

microsoft.bcl.build give actionable error message in cases package missing asking build again.

when coupled nuget 2.7 package restore automatic in visual studio , isn’t implemented through msbuild, experience transparent , smooth. however, doesn’t address build server scenarios yet still need run nuget.exe restore solution.sln prior build, or check-in .targets file if preferred.