send pdf file in xml message

You can transform the PDF file to Base64 Binary and wrap this into a container Element with type xs:base64Binary. For example you could use this schema definition to place your PDF file in the xml message.

<xs:complexType name="documentType">
 <xs:sequence>
    <xs:element minOccurs="0" name="mimetype" type="xs:string" />
    <xs:element minOccurs="0" name="filename" type="xs:string" />
    <xs:element name="content" type="xs:base64Binary" />
 </xs:sequence>
</xs:complexType>

You can use org.apache.commons.codec.binary.Base64 for this approach if you already have commons-codec in your project. It support use of chunked data and strings. For example:

// You can read in the PDF file with FileReader and get the bytes
// Please obey that this solution must be improved for large pdf files

Base64.encodeBase64(binaryData, true)