Xcd (exceed) is a new architectural description language (ADL), that we have been working on. The goal of Xcd is to be relatively easy to learn and use (compared with ADLs based on process algebras), provide first-class support for connectors (i.e., protocol abstractions) while guaranteeing that the specified protocols are realizable (it doesn't permit one to specify choreographies), and be formal, so that it can be analyzed.
This page describes the work on Xcd that has taken place during Mert Ozkaya's PhD thesis. Mert successfully defended his thesis on September 9, 2014 - see Mert Ozkaya's web page.
Our SEAA'13 article (Are We There Yet? Analyzing Architecture Description Languages for Formal Analysis, Usability, and Realizability) describes the problem that Xcd set out to solve, while our CBSE'14 article (Design-by-Contract for Reusable Components and Realizable Architectures) is the most recent and complete description of the Xcd language and approach.
You may also find this set of slides on Xcd useful.

You can access the latest version of the tool developed by Dr Ozkaya along with a number of case studies from the Xcd tool website, which is maintained by Dr Ozkaya.