MIME Multipart

Since Camel 2.17

This data format that can convert a Camel message with attachments into a Camel message having a MIME-Multipart message as message body (and no attachments).

The use case for this is to enable the user to send attachments over endpoints that do not directly support attachments, either as special protocol implementation (e.g. send a MIME-multipart over an HTTP endpoint) or as a kind of tunneling solution (e.g. because camel-jms does not support attachments but by marshalling the message with attachments into a MIME-Multipart, sending that to a JMS queue, receiving the message from the JMS queue and unmarshalling it again (into a message body with attachments).

The marshal option of the mimeMultipart data format will convert a message with attachments into a MIME-Multipart message. If the parameter "multipartWithoutAttachment" is set to true it will also marshal messages without attachments into a multipart message with a single part, if the parameter is set to false it will leave the message alone.

MIME headers of the mulitpart as "MIME-Version" and "Content-Type" are set as camel headers to the message. If the parameter "headersInline" is set to true it will also create a MIME multipart message in any case.
Furthermore the MIME headers of the multipart are written as part of the message body, not as camel headers.

The unmarshal option of the mimeMultipart data format will convert a MIME-Multipart message into a camel message with attachments and leaves other messages alone. MIME-Headers of the MIME-Multipart message have to be set as Camel headers. The unmarshalling will only take place if the "Content-Type" header is set to a "multipart" type. If the option "headersInline" is set to true, the body is always parsed as a MIME message.As a consequence if the message body is a stream and stream caching is not enabled, a message body that is actually not a MIME message with MIME headers in the message body will be replaced by an empty message. Up to Camel version 2.17.1 this will happen all message bodies that do not contain a MIME multipart message regardless of body type and stream cache setting.

Options

The MIME Multipart dataformat supports 5 options, which are listed below.

Name Default Java Type Description

Name	Java Type	Description
multipartSubType	`String`	Specify the subtype of the MIME Multipart. Default is mixed.
multipartWithoutAttachment	`Boolean`	Defines whether a message without attachment is also marshaled into a MIME Multipart (with only one body part). Default is false.
headersInline	`Boolean`	Defines whether the MIME-Multipart headers are part of the message body (true) or are set as Camel headers (false). Default is false.
includeHeaders	`String`	A regex that defines which Camel headers are also included as MIME headers into the MIME multipart. This will only work if headersInline is set to true. Default is to include no headers.
binaryContent	`Boolean`	Defines whether the content of binary parts in the MIME multipart is binary (true) or Base-64 encoded (false) Default is false.

multipartSubType

String

Specify the subtype of the MIME Multipart. Default is mixed.

multipartWithoutAttachment

Boolean

Defines whether a message without attachment is also marshaled into a MIME Multipart (with only one body part). Default is false.

headersInline

Boolean

Defines whether the MIME-Multipart headers are part of the message body (true) or are set as Camel headers (false). Default is false.

includeHeaders

String

A regex that defines which Camel headers are also included as MIME headers into the MIME multipart. This will only work if headersInline is set to true. Default is to include no headers.

binaryContent

Boolean

Defines whether the content of binary parts in the MIME multipart is binary (true) or Base-64 encoded (false) Default is false.

Message Headers (marshal)

Name	Type	Description
Message-Id	String	The marshal operation will set this parameter to the generated MIME message id if the "headersInline" parameter is set to false.
MIME-Version	String	The marshal operation will set this parameter to the applied MIME version (1.0) if the "headersInline" parameter is set to false.
Content-Type	String	The content of this header will be used as a content type for the message body part. If no content type is set, "application/octet-stream" is assumed. After the marshal operation the content type is set to "multipart/related" or empty if the "headersInline" parameter is set to true.
Content-Encoding	String	If the incoming content type is "text/*" the content encoding will be set to the encoding parameter of the Content-Type MIME header of the body part. Furthermore the given charset is applied for text to binary conversions.

Name

Type

Description

Message-Id

String

The marshal operation will set this parameter to the generated MIME message id if the "headersInline" parameter is set to false.

MIME-Version

String

The marshal operation will set this parameter to the applied MIME version (1.0) if the "headersInline" parameter is set to false.

Content-Type

String

The content of this header will be used as a content type for the message body part. If no content type is set, "application/octet-stream" is assumed. After the marshal operation the content type is set to "multipart/related" or empty if the "headersInline" parameter is set to true.

Content-Encoding

String

If the incoming content type is "text/*" the content encoding will be set to the encoding parameter of the Content-Type MIME header of the body part. Furthermore the given charset is applied for text to binary conversions.

Message Headers (unmarshal)

Name	Type	Description
Content-Type	String	If this header is not set to "multipart/*" the unmarshal operation will not do anything. In other cases the multipart will be parsed into a camel message with attachments and the header is set to the Content-Type header of the body part, except if this is application/octet-stream. In the latter case the header is removed.
Content-Encoding	String	If the content-type of the body part contains an encoding parameter this header will be set to the value of this encoding parameter (converted from MIME endoding descriptor to Java encoding descriptor)
MIME-Version	String	The unmarshal operation will read this header and use it for parsing the MIME multipart. The header is removed afterwards

Name

Type

Description

Content-Type

String

If this header is not set to "multipart/*" the unmarshal operation will not do anything. In other cases the multipart will be parsed into a camel message with attachments and the header is set to the Content-Type header of the body part, except if this is application/octet-stream. In the latter case the header is removed.

Content-Encoding

String

If the content-type of the body part contains an encoding parameter this header will be set to the value of this encoding parameter (converted from MIME endoding descriptor to Java encoding descriptor)

MIME-Version

String

The unmarshal operation will read this header and use it for parsing the MIME multipart. The header is removed afterwards

Examples

from(...).marshal().mimeMultipart()

With a message where no Content-Type header is set, will create a Message with the following message Camel headers:

Camel Message Headers

Content-Type=multipart/mixed; \n boundary="----=_Part_0_14180567.1447658227051"
Message-Id=<...>
MIME-Version=1.0

The message body will be:

Camel Message Body

------=_Part_0_14180567.1447658227051
Content-Type: application/octet-stream
Content-Transfer-Encoding: base64
Qm9keSB0ZXh0
------=_Part_0_14180567.1447658227051
Content-Type: application/binary
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="Attachment File Name"
AAECAwQFBgc=
------=_Part_0_14180567.1447658227051--

A message with the header Content-Type set to "text/plain" sent to the route

from("...").marshal().mimeMultipart("related", true, true, "(included|x-.*)", true);

will create a message without any specific MIME headers set as Camel headers (the Content-Type header is removed from the Camel message) and the following message body that includes also all headers of the original message starting with "x-" and the header with name "included":

Camel Message Body

Message-ID: <...>
MIME-Version: 1.0
Content-Type: multipart/related;
    boundary="----=_Part_0_1134128170.1447659361365"
x-bar: also there
included: must be included
x-foo: any value

------=_Part_0_1134128170.1447659361365
Content-Type: text/plain
Content-Transfer-Encoding: 8bit

Body text
------=_Part_0_1134128170.1447659361365
Content-Type: application/binary
Content-Transfer-Encoding: binary
Content-Disposition: attachment; filename="Attachment File Name"

[binary content]
------=_Part_0_1134128170.1447659361365

Dependencies

To use MIME-Multipart in your Camel routes you need to add a dependency on camel-mail which implements this data format.

If you use Maven you can just add the following to your pom.xml:

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-mail</artifactId>
  <version>x.x.x</version> <!-- use the same version as your Camel core version -->
</dependency>