There are certain things which we have to look at if we want to explore BizTalk server. It is also important to have a practice on each module if we want to capture it whole. One of the most important features of BizTalk is the BRE (Business Rule Engine) which is bit complex to understand but very simple to associate with the application. I will not go in to the deep of BRE rather I will explore my point for which I have written this blog. If we want to Implement BizTalk in any work place and with desire to utilize it maximum so we should use all of its component because they are merely based on the business composition.
It is very simple as I told earlier to implement it practically, I am going to mentioned certain points which might be helpful to call any BRE policy in .net

(1) Create a policy of any i.e Xml based, .net class , database table
(2) deploy that condition or policy rule
(3) best practice is to test that policy. We can test it by add instance. If we are using any schema so we need to generate instance and save it to any location. Then in the test policy window locate that xml with your specific change you want to do through policy.
(4) Add reference using Microsoft.RuleEngine;

(5) Now what we have to do, take an string xml of the schema in our string

(a)TypedXmlDocument td = null;
(b) string xml = host>PEPCO username>PEPCO ";
© td = new TypedXmlDocument("CallPolicySchema", xd); // this is the name which you have reference in your BRE
(d) Policy p = new Policy("YFNB"); // poicy name
(e) p.Execute(td);
(f) string _NoValue = td.Document.InnerXml.ToString();

So simple and Make life easy