Ruleflows can only be created by using the graphical ruleflow editor which is part of the Drools plugin for Eclipse. Once you have set up a Drools project (check the IDE chapter if you do not know how to do this), you can start adding ruleflows. When in a project, use "control+N" to launch the new wizard, or right-click the directory you would like to put your ruleflow in and select "New ... Other ...":

Figure 5.45. Ruleflow

Choose the section on "Drools" and then pick "RuleFlow file". This will create a new .rf file.

Next you will see the graphical ruleflow editor. Now would be a good time to switch to the "Drools perspective" (if you haven't done so already) - this will tweak the UI so it is optimal for rules. Then ensure that you can see the "properties" panel down the bottom of the eclipse window, as it will be necessary to fill in the different properties of the elements in your ruleflow. If you cannot see the properties view, open it using the Menu Window - Show View - Other ..., and under the General folder select the Properties view.

Figure 5.46. Groups

The RuleFlow editor consists of a palette, a canvas and an outline view. To add new elements to the canvas, select the element you would like to create in the palette and then add them to the canvas by clicking on the preferred location. For example, click on the RuleFlowGroup icon in the Component Pallette of the GUI - you can then draw a few rule flow groups. Clicking on an element in your ruleflow allows you to set the properties of that element.

Click on a ruleflow group, and you should see the following:

Figure 5.47. Group properties

You can see here you set the visible name, but you also need to set the actual group name that is used in the rules.

Next step is to join the groups together (if its a simple sequence of steps) - you use this by using "create connection" from the component palette. You should also create an "End" node (also from the component palette).

In practice, if you are using ruleflow, you will most likely be doing more then setting a simple sequence of groups to progress though. You are more likely modeling branches of processing. In this case you use "Split" and "Join" items from the component pallette. You use connections to connect from the start to ruleflow groups, or to Splits, and from splits to groups, joins etc. (i.e. basically like a simple flow chart that models your processing). You can work entirely graphically until you get the graph approximately right.

Figure 5.48. Complex ruleflow

The above flow is a more complex example. This example is an insurance claim processing rule flow. A description: Initially the claim data validation rules are processed (these check for data integrity and consistency, that all the information is there). Next there is a decision "split" - based on a condition which the rule flow checks (the value of the claim), it will either move on to an "auto-settlement" group, or to another "split", which checks if there was a fatality in the claim. If there was a fatality then it determines if the "regular" of fatality specific rules will take effect. And so on. What you can see from this is based on a few conditions in the rule flow the steps that the processing takes can be very different. Note that all the rules can be in one package - making maintenance easy. You can separate out the flow control from the actual rules.

Figure 5.49. Split types

Split types (referring to the above): When you click on a split, you will see the above properties panel. You then have to choose the type: AND, OR, and XOR. The interesting ones are OR and XOR: if you choose OR, then any of the "outputs" of the split can happen (ie processing can proceed in parallel down more then one path). If you chose XOR, then it will be only one path.

If you choose OR or XOR, then in the row that has constraints, you will see a button on the right hand side that has "..." - click on this, and you will see the constraint editor. From this constraint editor, you set the conditions which the split will use to decide which "output path" will be chosen.

Figure 5.50. Edit constraints

Choose the output path you want to set the constraints for (eg Autosettlement), and then you should see the following constraint editor:

Figure 5.51. Constraint editor

This is a text editor where the constraints (which are like the condition part of a rule) are entered. These constraints operate on facts in the working memory (eg. in the above example, it is checking for claims with a value of less than 250). Should this condition be true, then the path specified by it will be followed.