A method performed by data processing apparatus, the method comprising: operating one or more virtual machines on the data processing apparatus, wherein the one or more virtual machines are hosted by a host operating system that executes on the data processing apparatus, wherein the host operating system performs operations comprising: receiving, using one or more service bridges that execute in the host operating system, a plurality of requests from the one or more virtual machines , wherein each service bridge is associated with a different virtual machine of the one or more virtual machines, and wherein each request is a request to interface with one or more external services; modifying, using a respective service bridge, each request to be processed by the one or more external services ; and providing each modified request from the respective service bridge to the one or more external services , where the respective service bridge communicates with the one or more external services over a network, wherein each request in the plurality of requests is received by a paravirtualized socket at the respective virtual machine, where the paravirtualized socket adapter interfaces between the respective virtual machine and the corresponding service bridge using a shared memory ring buffer. operating one or more virtual machines on the data processing apparatus, wherein the one or more virtual machines are hosted by a host operating system that executes on the data processing apparatus, wherein the host operating system performs operations comprising: receiving, using one or more service bridges that execute in the host operating system, a plurality of requests from the one or more virtual machines , wherein each service bridge is associated with a different virtual machine of the one or more virtual machines, and wherein each request is a request to interface with one or more external services; modifying, using a respective service bridge, each request to be processed by the one or more external services ; and providing each modified request from the respective service bridge to the one or more external services , where the respective service bridge communicates with the one or more external services over a network, receiving, using one or more service bridges that execute in the host operating system, a plurality of requests from the one or more virtual machines , wherein each service bridge is associated with a different virtual machine of the one or more virtual machines, and wherein each request is a request to interface with one or more external services; modifying, using a respective service bridge, each request to be processed by the one or more external services ; and providing each modified request from the respective service bridge to the one or more external services , where the respective service bridge communicates with the one or more external services over a network, wherein each request in the plurality of requests is received by a paravirtualized socket at the respective virtual machine, where the paravirtualized socket adapter interfaces between the respective virtual machine and the corresponding service bridge using a shared memory ring buffer. <EOS>