Experiences gained from enabling Interoperability in Aladin

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Experiences gained from enabling
Interoperabilityin Aladin

• Pierre Fernique CDS

2
Two interaction levels

• Lower coupled level a classical approachgt
  command line parameters filesgt http
  parameters urls,gt script commands (stdin or
  http)gt widely open gt heavily used
• Highly coupled level a java approachgt java
  object interfacegt some implementations
  (VOPlot/AVO proto/CADC tools)

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The ExtApp context

• Connect VOPlot and Aladin
• Aladin asks VOPlot to create 2D diagrams
• VOPlot asks Aladin to visualize astronomical data
  on the sky
• Requires a management of the object selection
  callbacks (to select/highlight them in both
  applications)

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1. launch the other application
2. send objects
2. each application can call the other one to
highlight or select a list of objects
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ExtApp.java

• A symmetrical java interface implemented in both
  applications
• void loadVOTable(ExtApp app, InputStream in)
• void showVOTableObject(String oid)
• void selectVOTableObject(String oid)
• String execCommand(String cmd)

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Need for ExtApp2

• To complete VOTable exchange InputStream
  getVOTable(String dataSetID)
• To exchange images double
  getPixels(ra,dec,w,h) / (x,y,w,h) setPixels(x,y,p
  ix) / (ra,dec,pix)?
• To allow observer registering boolean
  add(this,MOUSEPIXEL)
• to transmit current mouse ra,dec position void
  pos(ra, dec)
• to transmit pixel under mouse position void
  pix(double pix)

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Lessons learnt

• Several solutions (depend on the interaction
  level)
• Close interactions easy to implement inside java
  world
• But how to cross the java border? gt PLASTIC