使用用户名/密码进行SAML断言 - 消息的真实含义是什么？

I need to create a some SAML 2.0 assertions, and I'm having trouble finding what the XML should really look like. Most of the documentation seems to be about using particular tools, not about the messages. I've got the schemas, with a plethora of possibilities, but I can't find an example of what the relevant messages actually look like in practice.I need to create a some SAML 2.0 assertions, an