The Message_PlugIn_Open contains a filename that refers to a file of parameters and attributes. This plugin uses this information to locate the correct data, classes, implementation, etc.
The file contains the concatenation of one or more binary records of the form:
Bytes Purpose
4 type of data
4 size of record (without header):
(4+n+p) + (4+s+q) + (4+t+r) bytes
4 size of name (unpadded)
n name, padded to word boundary
4 size of data (unpadded)
s data, padded to word boundary
4 size of MIME type (unpadded)
t MIME type, padded to word boundary
Integers are stored un little-endian order. Flags (parameters with void value whose presence or absence only is significant) are represented by a parameter of type DATA with zero length.
The parameters include:
· all the attributes of the OBJECT (or other) element that references this plugin
· all the PARAM elements enclosed within it
· special parameters created by the browser (rather than being part of the object element)
These parameters are passed exactly as seen in the HTML without any conversions. The data/URL/ref distinction is as given in the DTD (or OBJECT attributes) or in the VALUETYPE attribute of the PARAM element.
The plugin may implement its own URL fetching code, or it may have the browser fetch URLs on its behalf by issuing a URLAccess message to the browser.
Plugin data types
Value Meaning
0 terminator (this is the last word in the file)
1 data from PARAM
2 URL from PARAM
3 object ref from PARAM
4 special parameter from browser
Plugin special parameters
Name Meaning
BASEHREF The full URL of the document containing this object.
USERAGENT The name of the browser.
UAVERSION Version number of the browser (user agent) in format 'x.y'. If the plugin needs a specific browser feature, it may refuse to initialise if this version is not high enough.
APIVERSION Version number if the API in format 'x.y'. Changes in x mean a major incompatible change in formats. If the plugin doesn't understand this version it should refuse to initialise. Changes in y mean some new functionality introduced in a backwards compatible way.
BGCOLOR The background colour of the page, which can be used by the plug-in as the default background colour. The colour is passed in as a string in the format 'BBGGRR00'.
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