Unchangable fixed attribute value and the element date's format

i have to questions about the internet tv site i'm working on. first question is that the main element which is subscription has an attribute called (ServerIP) I want the server ip to be fixed and i want to give it a value that can never be changed. i tried this code but it didn't work, it prints nothing when i try to print it unless i give it a value in XML

<xs:attribute name="serverIP" type="xs:string" fixed="10.144.50.55"/>

The second question is, if i have an element called date,and i want to give it a specific pattern yyyy-mm-dd. i know i can do it for attributes using simple type. i tried this code but it didn't work

 <xs:element name="dateOfBirth" type="xs:date">
                                    <xs:complexType>
                                    <xs:simpleContent>
                                        <xs:restriction base="xs:date">
        <xs:pattern value="d{4}[-]d{2}[-]d{2}"/>
    </xs:restriction>
                                    </xs:complexType>
                                    </xs:simpleContent>
                                    </xs:element>

how do i know that my code worked? because when i give it a value in the format yyyymmdd in XML file it gets printed in the same format not like yyyy-mm-dd