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Chapter 12: Advanced Web Services Topics
The SOAP::Lite module provides transparent access to data packaged this way (there
is nothing to do on the client or server side to accept MIME-encoded messages; the
value of the image element in this example will be the picture itself when accessed
using
SOAP::Lite), however, the current version (0.55) doesn’t help to create mes-
sages with attachments. The
SOAP::MIME package (created by Byrne Reese and avail-
able from CPAN) extends support for parsing MIME messages providing direct
access to the attachments and also allows composing messages with attachments. Its
interface is simple:
use SOAP::Lite;
use SOAP::MIME;
use MIME::Entity;
my $cid = "bar";
my $ent = build MIME::Entity
Type => "image/gif",
Encoding => "base64",
Path => "image.gif",
'Content-Id' => "<$cid>",
Disposition => "attachment";
my $som = SOAP::Lite
->uri("...")
->proxy("...")
->parts($ent)
->send_image(SOAP::Data->name("foo")->attr({href => "cid:$cid"}));
It’s quite possible that this functionality will be included in a future version of the
SOAP::Lite module.
DIME and WS-Attachments
The structure of DIME message is somewhat similar to the structure of MIME mes-
sages (yet it uses a different terminology). Parts are called records and they consist of
a header and a payload, which can be either a complete object or a chunk of an
object. Similar to the MIME format, DIME uses headers to carry metadata about an
object encoded in a payload.
There are several important differences between the DIME and MIME formats. First,
MIME identifies the structure of content stored in the body by a type specified in a
Content-Type header, whereas DIME indicates the type of the payload in two ways.
The first way is identical to the usage of MIME media type as type identifier; the sec-
ond (optional) method defines the type through the use of the URI. The second dif-
ference between the formats is that even though DIME records are 32-bit word
aligned variable length records, each record includes a fixed length binary array with
flags and lengths of four elements that follow:
OPTIONS, TYPE, ID, and DATA.Asa
result, the length of the record is always known, and it’s easy to implement random
access.

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