Key difference between MSMP BRF+ rule and BRF+ flat rule ( lineitem by lineitem)

source:http://scn.sap.com/community/grc/blog/2013/08/20/key-difference-between-msmp-brf-rule-and-brf-flat-rule-lineitem-by-lineitem

In MSMP, Access Controls 10.0 and 10.1 provides extremely flexible and powerful tool to configure Access Control workflows. In this blog we will try to understand some basic concepts about MSMP and BRF+.

Before we can start creating any BRF+ rule for MSMP, we need to understand the difference between MSMP BRF+ rule and BRF+ flat rule ( lineitem by lineitem ). The logic executed in both the rules is same but the difference is in the input, output and the way it is processed.

Following are some of key differences:

1.) MSMP BRF+ flat rule (lineitem by lineitem):

This rule is called flat rule or lineitem by line item rule because this rule is called by MSMP multiple times, once for each lineitem. So if in access request you have added 3 roles/systems, then this BRF rule will be called 3 times. As an input to this rule, MSMP sends detail of one lineitem at a time and this BRF rule provides result for that one lineitem only. BRF+ flat rule is easy to create as no loop is required and only one decision table (or other expression) is required for the logic. For example, consider an access request with 3 roles/system. In this case the BRF flat rule is called 3 times by MSMP with following input and output:

Input provided by MSMP to BRF+ flat rule in first call:

Item Name	System	Role Type	LINEITEM KEY...
ROLE1	SYSTEM 1	SIN	0001

Output given by BRF+ to MSMP in first call:  

Lineitem Key	Rule Result
0001	RolePath

Input provided by MSMP to BRF+ flat rule in second call:

Item Name	System	Role Type	LINEITEM KEY...
ROLE2	SYSTEM 2	COM	0002

Output given by BRF+ to MSMP in second call:  

Lineitem Key	Rule Result
0002	RolePath

Input provided by MSMP to BRF+ flat rule in third call:

Item Name	System	Role Type	LINEITEM KEY...
SYSTEM1	SYSTEM1		0003

Output given by BRF+ to MSMP in third call:  

Lineitem Key	Rule Result
0003	SystemPath

So the flat rule is called once for each lineitem which makes its creation easier as no looping is required which is required in case of BRF+ rule.

2.) MSMP BRF+ rule:

In this case, all the lineitems (roles, systems and FFID...) present in the Access Request are sent to the BRF rule in form of a table. After processing, this rule has to return a table with lineitem key and result. For example, in case of initiator rule the input to BRF rule can be following table. The roles/system shown here are one that are added to access request.

INPUT sent by MSMP to BRF+

Item Name	System	Role Type	LINEITEM KEY...
ROLE1	SYSTEM 1	SIN	0001
ROLE2	SYSTEM 2	COM	0002
SYSTEM 1	SYSTEM 1		0003

For the above input, the output of BRF rule will be something like following:

OUTPUT given by BRF+ to MSMP

Lineitem Key	Rule Result
0001	RolePath
0002	RolePath
0003	SystemPath

Please note that we have not shown the decision table which contains the logic to determine the path in case of initiator rule. Since complete request details are sent by MSMP to BRF+ rule for execution, so this rule is called only once by MSMP. Hence it is required that the logic to loop on all the lineitems has to be done within BRF+ rule. The decision table or other condition is called within the loop so that it is executed for all the lineitems one by one.

Key differences between BRF+ rule and BRF+ flat rule are again summarized below:

BRF+ Flat Rule	BRF+ Rule
1.) Executed multiple times, Once for each lineitem	1.) Executed only once
2.) Details of one lineitem at a time passed to BRF rule by MSMP	2.) Complete request details passed to BRF rule by MSMP in form of a table
3.)Output of flat rule is result of one line item only	3.) Output of BRF+ rule is complete table with all lineitems
4.) Easy to create as no loop is required	4.) Complex as compared to flat rule as loop is required
5.) Some of business cases not possible in flat rule	5.) Almost all business cases can be achieved by BRF+ rule