Marshaled data is in redis server and I need to access it with PHP. No other options.
As far as I know, there is no deserializer for Ruby's internal Marshal format for PHP. You can write one, of course, here's the documentation.
Also, it simply might not be possible to represent the Ruby object as a PHP object, if the Ruby object uses features that PHP lacks. Either way, you will probably have to re-implement significant portions of Ruby's object model in PHP, in order to deserialize a Ruby Marshal string. For example, what if, after decoding the string, you end up with an object which is an instance of UserFoo with 3 instance variables referencing instances of class MyBar?
Anyway, here is a series of blog posts to get you started:
One thing you could try, is to run your PHP code on the JVM using one of the existing JVM implementations of PHP (e.g. Quercus or P8) and embed an instance of JRuby in your app to deserialize the string, provided the string can be deserialized with JRuby. (Similarly, you could do the same with IronPHP and IronRuby on the CLI.)
You need to use another format (that easier because you don't need to write your own unmarshal library) instead of ruby internal marshalling, something like JSON, XML etc.
Or you can simple execute ruby script from php which unmarshal ruby object.