Does anyone know good Object Constraint Language (OCL) tutorial?

Question

I came across couple of questions about OCL expressions. After reading some university slides and googling it I still cannot properly understand it.

I wonder if any of you guys know any good resources that I should read to understand this stuff.

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Constraints that bother me:

1. Everybody working in the department has the same manager.
2. Nobody in the company is the manager of him/herself.
3. Nobody in the company earns more than his manager.

For the 1st one I have:

context Department

inv self.stuff -> forAll(manager = self.staff.manager)

2nd one:

context Company

inv self.employee -> select(manager = manager.manager) -> isEmpty()

3rd one:

context Company

inv self.employee -> select(salary > manager.salary) -> isEmpty()

but I dont think these are right. What I'm most unsure of is whether in example 2 and 3 I actually compare individual employees with theirs actual manager / manager salary.

Answer 1

Finally got something good!

This is very informative document (PDF) from Object Management Group (OMG):

Object Constraint Language Specification

I love answering my own questions :)

Answer 2

The link to PDF file posted by @Artur has changed, Here is new link http://www.omg.org/spec/OCL/2.0/PDF/