The execution Data Transformation Manager (DTM) extracts, transforms, and loads data to run a data transformation job such as a preview or mapping.
When a service module in the Data Integration Service receives a request to run a job, the service module sends the request to the LDTM. The LDTM optimizes and compiles the job, and then sends the compiled job to the DTM. A DTM instance is started to run the job and complete the request.
A DTM instance is a specific, logical representation of the DTM. The Data Integration Service runs multiple instances of the DTM to complete multiple requests. For example, the Data Integration Service runs a separate instance of the DTM each time it receives a request from the Developer tool to preview a mapping.