Java Web Services in a Nutshell

SOAP Messages and MIME Headers

When a SOAP message is wrapped for transmission in HTTP (or another protocol, such as SMTP), suitable MIME headers must be created. At minimum, the wrapper must include the Content-Type and Content-Length headers along with the SOAPAction header that was described in Section 3.3.2, earlier in this chapter. Similarly, when a message is received, any MIME headers that accompany it must be extracted from the protocol-specific wrapper and be made part of the created SOAPMessage. The MIME headers associated with a SOAPMessage are held in an object of type javax.xml.soap.MimeHeaders .

In terms of the structure of an encapsulated SOAP message, the MIME headers logically appear outside the envelope (as shown in Figure 3-1), where they form the protocol-specific wrapper. In the case of a SOAP message with attachments, in addition to the headers in the outer wrapper, the SOAP message part and each of the attachment parts have their own collection of MIME headers that are distinct from those of the wrapper, as shown in Figure 3-2.

The MimeHeader and MimeHeaders Classes

MimeHeader and MimeHeaders are two of four concrete classes in the java.xml.soap package. The MimeHeader class represents a single MIME header and contains the header name and its associated value, which are set at construction time and cannot subsequently be changed.

MimeHeaders is a collection of MimeHeader objects. When it is created, a MimeHeaders object is empty; headers can be added using ...