Friday, February 26, 2016

Informatica Workflow Execution LM And DTM

Workflow Execution : Behind the scenes(Background Process)

ü  Whenever Integration Service receives a request to execute a workflow, it creates an Integration Service Process and it is typically called as pmserver process.
ü  An Integration Service can start one or multiple Integration Processes to run and monitor Workflows.
ü  Whenever a workflow is scheduled or changed, Workflow Manager interacts with Integration Service Process. This interaction happens over TCP/IP.  Integration Service process locks the Workflow and then knocks the Repository Service to get metadata about Workflow. Repository Service intern connects to Repository Database – fetches desired information – and gives it back to Integration Service process.
ü  Once Integration Service process receives metadata information back from Repository Service, it creates connections to Source and Target databases using ODBC or Native drivers. Integration Service process also creates connections to any lookup or stored procedure databases which are used by the Workflow. Once the data loading process is done, Integration Service process releases and closes all open database connections.
ü  Integration Service process is also responsible to start DTM process that will actually execute Workflow Sessions. Integration Service process passes Parameter File and Session information to DTM process, that helps it to retrieve required metadata from the repository.

Load Manager(LM) & Data Transformation Manager(DTM)
Ø  While running a Workflow ,the PowerCenter Integration services uses the Load Manager  process and the Data Transformation Manager Process (DTM) to run the  workflow and carry out workflow tasks. When the PowerCenter Server runs a  workflow, the Load Manager performs the following tasks:
                1. Locks the workflow and reads workflow properties.
2. Reads the parameter file and expands workflow variables.
3. Creates the workflow log file.
4. Runs workflow tasks.
5. Distributes sessions to worker servers.
6. Starts the DTM to run sessions.
7. Runs sessions from master servers.
8. Sends post-session email if the DTM terminates abnormally.

Data Transformation Manager (DTM)

Ø  When the PowerCenter Server runs a session, the DTM performs the following tasks:
1. Fetches session and mapping metadata from the repository.
2. Creates and expands session variables.
3. Creates the session log file.
4. Validates session code pages if data code page validation is enabled
5. Verifies connection object permissions.
6. Runs pre-session shell commands.
7. Runs pre-session stored procedures and SQL.
8. Creates and runs mapping, reader, writer, and transformation threads to   
    extract ,transform and load data.
9. Runs post-session stored procedures and SQL.
10. Runs post-session shell commands.
11. Sends post-session email.