Mikado Method A structured method for significant changes in complex code 

Change in a jungle of dependencies, broken code and undocumented features 

1. Set a goal Represent a starting point, and know when you are done. 

2. Experiment Make a simple change and see what breaks. 

3. Visualize Create a dependency graph of steps required to achieve the goal. 

site is implemented, you can note it in the graph with a check mark, as in figure 1.8. Mikado Goal Prerequisite: Immediate solution to errors when implementing Mikado Goal The Mikado Goal can have several direct prerequisites Add more prerequisites... ...linked to the previous Prerequisites can have common dependencies There can be lots of such dependent changes needed Figure 1.8 Check off the solutions as they are completed. 

4. Undo Revert changes after each experiment. Always experiment in a working state. 

Case Study Support SEPA in invoicing and payment application 

SEPA incasso 

SEPA incasso create processor 

SEPA incasso create processor parse SEPA files add transaction fields 

SEPA incasso allow uploads create processor parse SEPA files add transaction fields 

SEPA incasso allow uploads create processor parse SEPA files add transaction fields show SEPA fields 

SEPA incasso allow uploads create processor parse SEPA files add transaction fields show SEPA fields extract display logic store amounts 

SEPA incasso allow uploads create processor parse SEPA files add transaction fields show SEPA fields extract display logic store amounts parse stored amounts move parse to processor 

SEPA incasso allow uploads create processor parse SEPA files add transaction fields show SEPA fields extract display logic store amounts parse stored amounts move parse to processor 

SEPA incasso allow uploads create processor parse SEPA files add transaction fields show SEPA fields extract display logic store amounts parse stored amounts move parse to processor ✔ ✔ ✔ ✔ ✔ ✔ 

SEPA incasso allow uploads create processor parse SEPA files add transaction fields show SEPA fields extract display logic store amounts parse stored amounts move parse to processor ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ 

SEPA incasso allow uploads create processor parse SEPA files add transaction fields show SEPA fields extract display logic store amounts parse stored amounts move parse to processor ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ 

Benefits • Keep a stable code base. • Track progress. • Enables collaboration. • Increases communication. • Very light-weight. 

You need tests 

The Mikado Method Ola Ellnestam and Daniel Brolund http://www.manning.com/ellnestam