Schemas
S-Flux implement a simple way to show and access functionalities of other applications. Applications expose their functionalities using RDF documents written following the rules and properties defined in a set of particular OWL/RDF vocabularies that covers properties about mime-types, application's features and operations.
Mimetypes
This schema is used to describe mimetpyes and their content-type. It's really
simple and it definition can be found here.
The following is an exaplanation of the classes and their attributes:
| ContentType class | |
| No attributes |
| MimeType class | |
| name | String representing the name of the mimetype, for example 'text/plain' or 'image/jpeg' |
| hasContent | URI of the content-type |
| canApply | URI of an operation (see the operations section) that is suitable for the mimetype (this property is actually unused and isn't mandatory) |
As an example consider that you want to define the 'text' content-type and the 'text/plain' mimetype. You'll have to write a document like the following:
<?xml version="1.0"?> <!DOCTYPE rdf:RDF [<!ENTITY xsd "http://www.w3.org/2001/XMLSchema#">]> <rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#" xmlns:mm="http://sflow.org/schema/2005-06/mimetype#" xml:base="http://sflow.org/data/2005-06/mimetype"> <mm:ContentType rdf:ID="text" /> <mm:MimeType rdf:ID="text_plain"> <mm:name>text/plain</mm:name> <mm:hasContent rdf:resource="#text" /> </mm:MimeType> </rdf:RDF>
Applications
Applications needs to expose their features that varies from their name to the
version to what kind of mimetypes they can handle to what operations they can
perform to particular mimetypes and how to perform them. The schema definition
can be found here.
The following is an exaplanation of the classes and their attributes:
| Application class | |
| name | String representing the name of the application |
| license | String representing the type of license of the application (gpl, freeware, commercial...). This property is optional. |
| price | Price of the application. This property is optional. |
| webURL | Web address of the application. This property is optional. |
| version | Version of the application. This property is optional. |
| hasGUI | Boolean value, true if the application is a GUI application. This property is optional and false as default. |
| installationPath | Path to where is placed the application executable main file |
| execCommand | Name of the main executable application file |
| canRead | URI to the mimetype that the application can read |
| canWrite | URI to the mimetype that the application can modify |
| complexityLevel | Application complexity level expressed as a number that can vary from 1 to 5. This property is optional. |
| canPerform | Follow a RDF:Bag sequence of blank nodes having 'toMimeType' and 'operation' properties (see following properties) |
| operation | URI to an operation that the application can perform (see the operations section) |
| toMimeType | URI to the mimetype to which the application can perform the above operation |
| URLComment | Web address to a page that deeply describe the operation. This property is optional. |
| parameters | Follow a RDF:Seq sequence of blank-nodes describing the parameters needed by the operation. To describe them the next properties are used. |
| commandOption | String used by the command line to identify the operation, for example '--convert' |
| parameterType | URI identifying the type of the parameter (string, integer or boolean). This property is optional because not all parameters need a value. The URI has to be part of XML-Schema |
| parameterOrder | Specify an order to the parameters. It's needed because actually librdf engine don't handle RDF:Seq sequences very well. This property is optional. |
| parameterLabel | This property is optional and useful only when the parameter need a value. It's a string that will appear on S-Flux GUI indicating what the parameter is expecting. For example for an image rotation operation it will be "Rotation angle:" |
| parameterHelp | A small help string about the parameter. This property is optional. |
So let's see how an image editing program named 'imgedit' would define itself and its image concatenation functionality:
<?xml version="1.0"?>
<!DOCTYPE rdf:RDF [<!ENTITY xsd "http://www.w3.org/2001/XMLSchema#">]>
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xmlns:apps="http://sflow.org/schema/2005-06/applications#"
xml:base="http://www.example.org/applications">
<apps:Application rdf:ID="imgedit">
<apps:name>ImgEdit</apps:name>
<apps:license>GPL</apps:license>
<apps:price>0</apps:price>
<apps:webURL>http://www.example.org/applications/imgedit</apps:webURL>
<apps:installationPath>/usr/bin</apps:installationPath>
<apps:execCommand>imgedit</apps:execCommand>
<apps:version>1.1</apps:version>
<apps:hasGUI>true</apps:hasGUI>
<apps:complexity>1</apps:complexity>
<apps:canWrite rdf:resource="http://sflow.org/data/2005-06/mimetype#image_jpeg" />
<apps:canWrite rdf:resource="http://sflow.org/data/2005-06/mimetype#image_gif" />
<apps:canPerform>
<rdf:Bag>
<rdf:li rdf:nodeID="_concatenation" />
</rdf:Bag>
</apps:canPerform>
</apps:Application>
<rdf:Description rdf:nodeID="_concatenation">
<apps:toMimeType rdf:resource="http://sflow.org/data/2005-06/mimetype#image_jpeg" />
<apps:toMimeType rdf:resource="http://sflow.org/data/2005-06/mimetype#image_gif" />
<apps:operation rdf:resource="http://sflow.org/data/2005-06/operation#imageConcatenation" />
<apps:parameters>
<rdf:Seq>
<rdf:li rdf:nodeID="_concatenation_p1" />
</rdf:Seq>
</apps:parameters>
</rdf:Description>
<rdf:Description rdf:nodeID="_concatenation_p1">
<apps:commandOption>--append</apps:commandOption>
</rdf:Description>
Operations
This schema is used to define the classes that will describe the categories in which the operations can be organized and the single operations. The schema can be found here.
The following is an exaplanation of the classes and their attributes:
| Category class | |
| name | String representing the name of the category |
| hasFather | URI of the eventual father category. This property is optional. |
| Operation class | |
| name | String representing the name of the operation |
| returnMimeType | If the operation produce a new document as result this property describe the URI of the resulting mimetype. This property is optional. |
| groupOperation | Boolean value. It's true if the operation need one or more file in input and produce a single file in output. This property is optional. |
| shortComment | Little help string. This property is optional. |
| hasCategory | URI to the category of the operation. This property is optional. |
As an example this is how you can describe the 'Search and replace' operation on a text document:
<ops:Category rdf:ID="TextEdit"> <ops:name xml:lang="en">Edit</ops:name> <ops:name xml:lang="it">Modifica</ops:name> </ops:Category> <ops:Operation rdf:ID="textReplace"> <ops:name xml:lang="en">Text replace</ops:name> <ops:name xml:lang="it">Sostitusci testo</ops:name> <ops:returnMimeType rdf:resource="http://sflow.org/data/2005-06/mimetype#text_plain" /> <ops:hasCategory rdf:resource="#TextEdit" /> <ops:shortComment xml:lang="en">Replace a string with another one</ops:shortComment> <ops:shortComment xml:lang="it">Sostituzione di una stringa con un'altra</ops:shortComment> <ops:URLComment>http://www.example.org/operations/replace.html</ops:URLComment> </ops:Operation>