You can start developing with these minimal requirements, but since you will be developing full featured enterprise applications, be prepared to learn a lot.
- Basic database knowledge
- Basic programming (e.g. Excel formulas)
In order to create complete working applications, but without heavy business logic, you will need to have the following skills:
- Intermediate SQL
- Basic XSLT/XPath
Business Logic/API Development
In order to be able to deliver complex business logic, you will need to have additional knowledge.
- Advanced XSLT/XPath
- Advanced JSON/XML
- .NET / C# (in case of developing custom service adapters)