Proper RESTful SOA approach in PHP applications?
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So, i've been reading a lot on SOA's lately and been trying to implement something useful. I have started with a simple blog, creating the RESTful API. So far, so good. It works perfectly. However, i'm starting to pull my hair off when writing the web interface that will consume the RESTful API. I don't know if i'm doing the right thing.

For example, the web interface has an admin panel. That admin panel makes HTTP requests to the API, through file_get_contents and stream options. Right now, the API is localhost, as well the web interface, but the whole process is a little slower. Is this right? Is this the proper way of implementing a SOA? Also, i'm dealing with little bits of duplicated code for validation. Where should i validate data? In the API or the web interface? What is the best approach?

Tips, tutorials and, specially, books are welcome. This is being implemented using Silex, built on top of Symfony components.