It is easier to inspect the logic manually in simple forms but companies use InfoPath not to create simple forms but to create forms in an easy and simple way. These forms can get quite complex and large. Once developed and deployed, there are different techniques that developers can use to track down errors but even at design time inspecting and fixing errors in the form can be a tedious job. Forms can have hundreds of nodes or may be 20-30 fields in a single view. It's not easy to find problems with the data sources without the help of a tool. Unfortunately, logic inspector and design checker, tools that come with InfoPath are usually overlooked and not taken advantage of by the developers.

There are some errors that become evident only after when a developer tries to deploy the form. Large number of data sources or fields is not the only problem, no form is complete without the data validation checks, rules and business logic. Logic Inspector enables developers to find problems with the form before they try and deploy it on the destination server. It allows them to view the data validation checks, rules, calculated default values, and business logic, all in one place. Design Checker is another tool that can be used to check the form design for performance related issues before deploying the form. I admit, even I used to underestimate the power of this tool but It really helped me once to resolve performance issues in a large form that comprised of hundreds of nodes, validation checks, rules and thousands of lines of business logic code. Let's take a look at the Logic Inspector first before moving on towards the Design Checker.