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.