Informatica – Post/Pre Session Variable Assignment

Hello Friends, Time for some learning. This time i have taken up the Informatica Variables and Parameters which i am very much fond of 🙂

This time i have taken up something that i came across in one of the development my team was involved in, and there was a need to pass a value from one task/session to another as we had a check with respect to the value we get from one session to be used going forward in the process.

For instance, my requirement is to check on the count of records from session_1 and then to count on records in session_2 but with the same counter (increment from where the Session_1 count ended) ending up with the total count of records. Something like, i had 100 records in session_1 and then i have to count from there as 100+1 and so on for the session_2. Looks simple, but quite a nail biting and challenging experience while we try getting it in Informatica!!

And then we came across this approach/feature available in the Informatica ‘Pre-Session/Post-Session Variable Assignment’. Which was all about the assigning of Variable values between the Sessions and it’s Parent Worklet/Workflow and vice-versa. Interesting right? If not clear lets go with a step by step illustration for a better understanding on this.

1. All we need to do is define a Counter variable/Parameter $$v1_Count for the session_1, and then our session runs to populate $$v1_Count as a usual Mapping Variable/Parameter does.

2. Next is, to assign this value to the common Variable (that acts as an intermediate between two of our sessions) which will be the Parent Worklet/Workflow Variable defined as any other Variable in the Edit Workflow/Worklet Options. In my case i have Workflow variable $$wf_v_Count defined.

3. Now in the session_1, Components tab -> lets edit the “Post session Variable assignment” option (it can be on failure or on success),

(i) Post-session on success variable assignment
(ii) Post-session on failure variable assignment

and i define it as – “Parent_Workflow/Worklet_Variable = Mapping_Variable/Parameter”

i.e., $$wf_v_Count = $$v1_Count

So here we have the $$v1_Count value open for any task,session or Worklet under the same parent can take up and use it for processing.

4. In our case, for the next session_2, i have to go for Components tab -> “Pre Session Variable Assignment” to be defined to assign the value from the $$wf_v_Count to the respective session’s Mapping Variable/Parameter $$v2_Count.

So we define it as “Mapping_Variable/Parameter = Parent_Workflow/Worklet_Variable”

i.e., $$v2_Count = $$wf_v_Count

The same can be used all over the Parent Workflow/Worklet, in any decision tasks or on link conditions. Thus we have now passed on the value from one session to the other and can be processed thereafter. Hope this was an interesting and helpful piece to you.

Do post your comments on any corrections or queries with respect to this. Share this if it can help someone.

Informatica $$Parameters and their scopes

Important Points:

The parameters are detected by the Informatica IS with a $$ and takes the parameter name from the $$ till the occurrence of the ‘=’ symbol, anything between $$ and = shall be considered as the parameter name.

Similarly any value from the ‘=’ till the end of the line shall be considered as the value to the respective parameter.

The parameter files are saved with an extension .prm

There are different levels of precedence of the parameters,

The mapping level precedence

This is the least precedence level, defined as initial value in the mapping designer itself.

The Global precedence:

These are the parameters defined in the whole workflow’s parameter files, directly as parameters.

Example:

[gloabal]

$$Param_test=2011

The Session level precedence:

The session level parameters are defined in the workflow’s parameter file with the session name, this has the precedence over the global parameters.

Example:

$$Param_test=2011

[s_sample_session_name]

$$Param_test=2012

So here in the session ‘s_sample_session_name’, the ‘’$$Param_test” holds the value 2012 and not the 2011 for the higher precedence by the session level parameter.

The Session Param file precedence:

There can also be a separate parameter file that can be defined for a session, where the parameter value defined in this param file takes the higher precedence than the one defined in the workflow’s param file.

The Path defined parameter precedence:

There can be situations where a reusable session used in two different worklets can need two different param values at two instances. This can be very well achieved by indicating the specific session name through its worklet as in the below example.

Example:

If s_session_test1 is used in WKLT_workletA and WKLT_workletB with two different values, then we can define the parameter value as,

[FLD_folder_name.WF:wf_workflow_name.WT:WKLT_workletA.S:s_session_test1]

$$Param_name=2011

[FLD_folder_name.WF:wf_workflow_name.WT:WKLT_workletB.S:s_session_test1]

$$Param_name=2012

So the same session uses the same parameter, but with different values at different worklets.