Estimation for ABAP project

Dear all,

We have an ABAP project, how can you estimate total of effort we spend to complete them. Please guide me some ways to estimate the ABAP development project ?

By the way, I want to know how to measure the productivity of a ABAP developer ?. What metric should we base on ?

For example: in VB or C++ projects, we measure productivity of developers base on number of code lines per day.

Please help me or guide me some measurement method.

Thank you.

VuPN