PHP and its community has evolved really fast in the last few years to allow for professional architectures and solutions. However, there are thousands of existing PHP applications which have not evolved in the meantime and are now crippled and unmaintainable because of that. These applications represent a real threat to the competitiveness of the business that relies on them.
The best approach in terms of business to solve this problem is progressive rewrite. Symfony2 and its modular architecture make it possible. This talk covers the main technical difficulties of the progressive approach when rewriting legacy PHP applications, and the corresponding solutions, some of which rely on the modularity of Symfony2.