The straightforward solution to integrate WPML with third party translation services was to do it via dedicated plugins. A separate plugin for each company offering translation services could do the trick. However, this approach had a few drawbacks. For example, WPML developers would need to update and test all these plugins whenever the WPML core plugins received an update, and vice versa; when the API used by the external service changed, you needed to incorporate the change to WPML and test it as well.

WPML knows how to communicate with the Translation Proxy, and the Translation Proxy knows how to communicate with translation services. If a Translation Service company happened to change their API, we needed to only update the Translation Proxy.

intermediate service