The HIS 2013 Software Development Kit (SDK) was not included with HIS 2013 as it has been with all prior releases of Host Integration Server. The HIS 2013 SDK has been packaged as a separate download package. This allows updates to the SDK to be made available before the next release of Host Integration Server.
For those customers that use the Transaction Integrator (TI) feature, you will want to go through the ApplicationIntegrationStarterGuide sample because it provides most of the documentation that is available for the many new features in the HIS 2013 version of TI. This sample is located under the \Microsoft Host Integration Server 2013 SDK v1.0\ApplicationIntegration\WindowsInitiated folder after the SDK is installed.
The following link provides an overview to what new with TI in HIS 2013, but the referenced sample includes more details: