Please note that in spite of the title of this page, there is no DeploymentTransferIOFilter interface.
The concept of a 'content transformer' is symmetrical: that which is done can later be undone. Content which is compressed before being sent is uncompressed on the receiving end. Likewise, content which is encrypted before it leaves the authoring server can be decrypted on the deployment target. These two symmetrical components are represented by separate interfaces, the DeploymentTransportInputFilter (relevant to the deployment receiver) and the DeploymentTransportOutputFilter (relevant to the authoring server). If a single component implements both of these interfaces, it is capable of being used on both ends of the communications link.
There are two example implementations of these interfaces, and both implementations implement both interfaces. To use them, configure the same class with the same parameters on both the authoring server and the deployment receiver. Note, however, that these are just examples and are somewhat limited. They are usable as-is, but if extra functionality is required, code to implement these interfaces will need to be written.