Mediaflux concepts

Mediaflux (ref) is the underlying storage platform that pshell communicates with.

Instead of files and folders (pshell) you have:

assets - the file content and associated metadata
namespaces - remote folder structure on the mediaflux server

Mediaflux metadata is:

XML-based
has it's own query language

The main commands, operating on assets and asset metadata, are:

asset.get - display metadata for an asset
asset.set - alter metadata for an asset
asset.query - find assets based on metadata queries

Mediaflux commands

These can be run in pshell or the vendor's own client (aterm.jar)

Retrieving metadata

The general command is:

asset.get :id ASSET-ID
asset.get :id "path=FULL-PATH-TO-FILE"

If we wanted to extract a specific piece of information, such as the checksum, we use the optional xpath argument:

pawsey:/projects>asset.get :id 69776098 :xpath content/csum
value = 384461DE

Populating metadata

The general command is:

asset.set :id ASSET-ID <ELEMENT AND VALUE>

For example, this is equivalent to a rename:

asset.set :id 2958 :name "new name"
version="2"     -changed-or-created="true" -id="2958" -stime="12095"

Note: a new version of the asset is created - reflecting the fact that the name has been altered.

A more complex example, where we assign a geospatial location (in this case a point) to an asset:

asset.set :id 69776160 :geoshape < :point < :latitude 31.95 :longitude 115.86 :elevation 10.0 > >
version="3"     -changed-or-created="true" -id="2958" -stime="12097"

This last case is an example of specifying an XML document that details the xpath + value for metadata items.

It is equivalent to an XML metadata document that looks like this:

<geoshape>
	<point>
		<latitude> 31.95 </latitude>
		<longitude> 115.86 </longitude>
		<elevation> 10.0 </elevation>
	</point>
</geoshape>

Slight digression - metadata templates

The doc type shows the metadata that can be queried and specified.

Custom doc types can be made.

Asset is a special "first-order" type attached to everything.

Custom doc types get added under the <meta> element.

asset.doc.type.describe :type asset

Things such as the asset name and the geoshape and other items in the asset template are first order metadata items and treated as described above in terms of asset.get and asset.set.

Custom metadata templates are slightly different, as they sit under the <meta> element of the asset, rather than at the top level.

pawsey:/projects>asset.doc.type.describe :type csiro:seismic
...
    definition    
        element     -type="string" -min-occurs="0" -name="name" -max-occurs="1"
        element     -type="string" -min-occurs="0" -name="geometry" -max-occurs="1"
        element     -type="string" -min-occurs="0" -name="basin" -max-occurs="1"
        element     -type="string" -min-occurs="0" -name="sub-basin" -max-occurs="1"

Applying this template to a piece of data could be achieved as follows:

pawsey:/projects>asset.set :id 69776098 :meta < :csiro:seismic < :name "Perth" :geometry "sprawling" > >
version="5"     -changed-or-created="false" -stime="76619960"


pawsey:/projects>asset.get :id 69776098 :xpath meta/csiro:seismic
value="5"    
value="Perth"    
value="sprawling"    


pawsey:/projects>asset.get :id 69776098 :xpath meta/csiro:seismic/name
value="Perth"

Querying the metadata

The simple form of an asset query is:

asset.query :where "LOGICAL-EXPRESSION"

Here is an example of searching for assets in a directory that match a pattern:

pawsey:/projects>asset.query :where "namespace='/projects/Data Team/testfiles' and name='*007*.jpg'" 
id="69776098"     -version="5"
id="69776099"     -version="1"
id="69776101"     -version="1"
id="69776103"     -version="1"
id="69776104"     -version="1"
id="70486890"     -version="1"
id="70486891"     -version="1"
id="70486892"     -version="1"
id="70486893"     -version="1"

Note that this is equivalent to the pshell "simplified language" command:

pawsey:/projects/Demo/sean>ls *007*.jpg
5 items, 29 items per page, remote folder: /projects/Demo/sean
 69776131   | online  |  17.02 KB | i000765.jpg
 69776132   | online  |  17.21 KB | i000767.jpg
 69776133   | online  |     17 KB | i000769.jpg
 69776134   | online  |  19.09 KB | i000768.jpg
 69776137   | online  |  17.59 KB | i000766.jpg
Page 1 of 1, file filter ['*007*.jpg']:

However, using Mediaflux language allows more sophisticated tasks to be performed.

Here's how we could retrieve the checksums of the above matches:

pawsey:/projects>asset.query :where "namespace>='/projects/Data Team/testfiles' and name='*007*.jpg'" :action get-value :xpath content/csum
asset     -version="5" -id="69776098"
    value="384461DE"    
asset     -version="1" -id="69776099"
    value="561CDB00"    
asset     -version="1" -id="69776101"
    value="F517536B"    
...

Here's how we could sum the content sizes of the files in the above match:

pawsey:/projects>asset.query :where "namespace>='/projects/Data Team/testfiles' and name='*007*.jpg'" :action sum :xpath content/size
value="143330"     -nbe="9"

We could also move those files somewhere else:

pawsey:/projects/Demo/sean>mkdir newfolder

pawsey:/projects/Demo/sean>asset.query :where "namespace>='/projects/Data Team/testfiles' and name='*007*.jpg'" :action pipe :service -name asset.move < :namespace /projects/Demo/sean/newfolder >

pawsey:/projects/Demo/sean>cd newfolder/
Remote: /projects/Demo/sean/newfolder

pawsey:/projects/Demo/sean/newfolder>ls
5 items, 29 items per page, remote folder: /projects/Demo/sean/newfolder
 69776131   | online  |  17.02 KB | i000765.jpg
 69776132   | online  |  17.21 KB | i000767.jpg
 69776133   | online  |     17 KB | i000769.jpg
 69776134   | online  |  19.09 KB | i000768.jpg
 69776137   | online  |  17.59 KB | i000766.jpg

Exercises

Exercise 1 - displaying metadata

Upload an image file (for example one of the jpgs from the previous exercises) and then inspect the metadata in the system.

Remember that you only have readwrite access to /projects/Demo

Solution to exercise 1

pawsey:/projects/Demo/sean>put IMG_0009.jpg
Total files=1, transferring...  
Progress: 100% at 0.0 MB/s  
Completed.

pawsey:/projects/Demo/sean>asset.get :id "path=/projects/Demo/sean/IMG_0009.jpg"
asset     -version="1" -id="69776107" -vid="74447906"
    type="image/jpeg"    
    namespace="/projects/Data Team/testfiles"    
    path="/projects/Data Team/testfiles/IMG_0009.jpg"    
    name="IMG_0009.jpg"    
...

Exercise 2 - modifying metadata

Using the file uploaded above, add geospatial location metadata to the asset and confirm by displaying the metadata.

Solution to exercise 2

pawsey:/projects>asset.set :id 69776098 :geoshape < :point < :latitude 17.0 :longitude 178.0 :elevation 30.0 > >
version="6"     -changed-or-created="true" -stime="76628158"
pawsey:/projects>asset.get :id 69776098 :xpath geoshape
value    
    geoshape     -type="point" -datum="WGS84"
        point    
            latitude="17"    
            longitude="178"    
            elevation="30.0"

Exercise 3 - querying metadata

Recursively search namespaces starting from /projects/Data Team to find the asset where the metadata element mf-note/note has a literal string value equal to cat. Download the file and verify that it is a cute cat.

Solution to exercise 3

pawsey:/projects>asset.query :where "namespace>='/projects/Data Team' and mf-note/note='cat'"
id="69776108"     -version="2"
pawsey:/projects>asset.get :id 69776108 :xpath namespace :xpath name
value="/projects/Data Team/testfiles"    
value="IMG_0033.jpg"    
pawsey:/projects>get /projects/Data Team/testfiles/IMG_0033.jpg
Total files=1, transferring ...  
Progress=100%, rate=0.0 MB/s  
Completed.
pawsey:/projects>exit

iblis:~> open IMG_0033.jpg

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