envoy/src/main/resources/message_schema.xsd

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
	targetNamespace="https://github.com/informatik-ag-ngl"
	xmlns="https://github.com/informatik-ag-ngl"
	elementFormDefault="qualified">

	<xs:element name="Messages">
		<xs:complexType>
			<xs:sequence>
				<xs:element name="Message" type="Message" minOccurs="0"
					maxOccurs="unbounded" />
			</xs:sequence>
		</xs:complexType>
	</xs:element>

	<xs:complexType name="Message">
		<xs:sequence>
			<xs:element name="MetaData">
				<xs:complexType>
					<xs:sequence>
						<xs:element name="Sender" type="xs:long" />
						<xs:element name="Recipient" type="xs:long" />
						<xs:element name="Date" type="xs:dateTime" />
						<xs:element name="State">
							<xs:simpleType>
								<xs:restriction base="xs:string">
									<xs:enumeration value="Waiting"/>
									<xs:enumeration value="Sent"/>
									<xs:enumeration value="Received"/>
									<xs:enumeration value="Read"/>
								</xs:restriction>
							</xs:simpleType>
						</xs:element>
					</xs:sequence>
				</xs:complexType>
			</xs:element>
			<xs:element name="Content" maxOccurs="unbounded">
				<xs:complexType>
					<xs:sequence>
						<xs:element name="text" type="xs:string" />
					</xs:sequence>
					<xs:attribute name="type" type="xs:string" />
				</xs:complexType>
			</xs:element>
		</xs:sequence>
	</xs:complexType>

</xs:schema>