I am aware of the use of
pkg to install an individual package file, but it does not include a repository infrastructure like other Linux distributions. Is there any solution that behaves like
yum or `apt on the Solaris 11 Express platform?
Solaris IPS (Image Packaging System) is definitely based on a repository infrastructure and behaves like yum/apt if you mean automatically handles dependencies.
You can list the publisher's repositories with this command:
You can add and remove publishers and you can also create your own repository.
More details here
OpenCSW (open fork of Blastwave) allows you to use pkgutil to install software from their repositories. E.g.
pkgutil --install coreutils