Studio Developer Manual / Version 2110
Table Of Contents
When a blob is uploaded into a property field, CoreMedia Studio
detects an appropriate MIME type based on name and content of the uploaded file.
This is done with the help of the mimeTypeService bean, which is based
on Apache Tika. This service is able to detect many common file types.
If the file type is unknown, the MIME type suggested by the uploading browser
will be used.
MIME Type Service Configuration
If you require to adapt the MIME Type Service Configuration, as proposed in subsequent paragraphs, find more details in Section “MIME Type Mappings” in Content Application Developer Manual.
Adding new file types can mostly be achieved by adding a file
org/apache/tika/mime/custom-mimetypes.xml to the
classpath of CoreMedia Studio Server. The path may be adapted by setting
mimeTypeService.mimeTypesResourceNames accordingly.
You will find an example for such a configuration in
Example 9.95, “Override *.exe MIME Type Detection”.
<?xml version="1.0" encoding="UTF-8"?>
<mime-info>
<mime-type type="application/acme">
<_comment>New MIME Type Mapping</_comment>
<glob pattern="*.acme"/>
</mime-type>
<mime-type type="application/x-dosexec">
<_comment>Override Tika Default</_comment>
<sub-class-of type="application/x-msdownload"/>
<glob pattern="*.exe" weight="100"/>
<magic priority="100">
<match value="MZ" type="string" offset="0"/>
</magic>
</mime-type>
</mime-info>
Example 9.95. Override *.exe MIME Type Detection
Details about the example:
The first entry is about adding some new MIME type for files with
acmeextension.The second entry overrides the default Tika configuration enforcing all
*.exeto be mapped toapplication/x-dosexec.While the default Tika configuration already maps
*.exeto MIME typeapplication/x-dosexec, it adds subsequent overrides toapplication/x-msdownloadwithformatproperty, to distinguish for example 32bit from 64bit applications.To override it, you need to duplicate the
<magic>pattern of the original definition and provide a higher priority than in Tika's default configuration. Valid priorities are from 0 to 100, where 50 is the default.
For a reference of all elements and attributes in
custom-mimetypes.xml have a look at
the API documentation of
org.apache.tika.mime.MimeTypesReader.
As stated in the documentation, the DTD is compliant to
freedesktop MIME-info DTD. Note, though, that it only
contains a subset of attributes and elements. Nevertheless, you may find
some more valuable information in the official specification located at
freedesktop.org: Shared MIME Info Specification.
If you need to override existing mappings, the approach via
custom-mimetypes.xml may not be sufficient.
In this case you may need to set mimeTypeService.tikaConfig.
Note though, that, in contrast to custom-mimetypes.xml,
this requires defining all MIME types by yourself. For a start, you may want
to take tika-mimetypes.xml for reference, which can be
found in the
Apache Tika GitHub Repository.
Example where overriding may fail:
You may struggle with Tika reporting duplicate definitions. For example,
take the re-mapping of *.exe above. If you skipped
the <magic> element, Tika would report about a duplicate
definition for *.exe without being able to get the
priorities straight. Thus, you need to tune your
adaptions and have a deep understanding about the
<mime-info> configuration. And as Tika does not support
<glob-deleteall> and <mime-deleteall>
as specified by freedesktop MIME-info DTD, there is
no straightforward way to enforce your MIME-type detection, while trying
to benefit from existing MIME-type detection configuration for types you
want to keep as is.
