Hiding and Storing/caching of Application Specific data in MS Word 2003 documents

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.Office.Core;
using System.Reflection;

namespace WordAddIn1
{
    public class CustomDocumentPropertyManager
    {
        public string GetPropertyValue(string propertyName,ref Microsoft.Office.Interop.Word.Document Doc)
        {
            string propertyValue = String.Empty;
            Type validatedType = null;
            object oDocCustomProps = null;
            Type typeDocCustomProps = null;
            string prop = String.Empty;
            object property = null;
            try
            {
                oDocCustomProps = Doc.CustomDocumentProperties;
                typeDocCustomProps = oDocCustomProps.GetType();
                prop = propertyName; //property to extract

                property = typeDocCustomProps.InvokeMember("Item",
                                                    System.Reflection.BindingFlags.Default |
                                                    System.Reflection.BindingFlags.GetProperty,
                                                    null, oDocCustomProps, new object[] { prop });

                validatedType = property.GetType();
                //to check the value of custom document property
                propertyValue = validatedType.InvokeMember("Value",
                    System.Reflection.BindingFlags.Default |
                    System.Reflection.BindingFlags.GetProperty,
                    null,
                    property,
                    new object[] { }).ToString();

            }
            catch (System.Reflection.TargetInvocationException ex)
            {
                propertyValue = String.Empty;
            }
            catch (Exception ex)
            {
                propertyValue = String.Empty;
            }
            return propertyValue;

        }

        public bool AddCustomDocumentProperty(string propertyName, string propertyValue,ref Microsoft.Office.Interop.Word.Document Doc)
        {
            bool success = false;
            Type validatedType = null;
            object oDocCustomProps = null;
            Type typeDocCustomProps = null;
            string prop = String.Empty;
            object property = null;
            try
            {
                oDocCustomProps = Doc.CustomDocumentProperties;
                typeDocCustomProps = oDocCustomProps.GetType();
                prop = propertyName;

                property = typeDocCustomProps.InvokeMember("Item",
                                                    System.Reflection.BindingFlags.Default |
                                                    System.Reflection.BindingFlags.GetProperty,
                                                    null, oDocCustomProps, new object[] { prop });


            }
            catch (System.Reflection.TargetInvocationException ex)
            {
                oDocCustomProps = Doc.CustomDocumentProperties;
                typeDocCustomProps = oDocCustomProps.GetType();

                string strIndex = propertyName;
                string strValue = propertyValue;
                object[] oArgs = {strIndex,false,
                                                 MsoDocProperties.msoPropertyTypeString,
                                                 strValue};

                typeDocCustomProps.InvokeMember("Add", BindingFlags.Default |
                                           BindingFlags.InvokeMethod, null,
                                           oDocCustomProps, oArgs);

                success = true;


            }
            catch (Exception ex)
            {
                success = false;
            }
            return success;
        }

        public bool ChangePropertyValue(string propertyName, string propertyValue,ref  Microsoft.Office.Interop.Word.Document Doc)
        {
            bool success = false;
            object oDocCustomProps = null;
            Type typeDocCustomProps = null;
            string prop = String.Empty;
            object property = null;

            try
            {
                oDocCustomProps = Doc.CustomDocumentProperties;
                typeDocCustomProps = oDocCustomProps.GetType();
                prop = propertyName;

                property = typeDocCustomProps.InvokeMember("Item",
                                                    System.Reflection.BindingFlags.Default |
                                                    System.Reflection.BindingFlags.GetProperty,
                                                    null, oDocCustomProps, new object[] { prop });

                typeDocCustomProps.InvokeMember("Value",
                                                  System.Reflection.BindingFlags.Default |
                                                  System.Reflection.BindingFlags.SetProperty,
                                                  null,
                                                  property,
                                                  new object[] { propertyValue });

                success = true;
            }
            catch (Exception ex)
            {
                success = false;
            }

            return success;
        }
    }


}