Class: VORuby::Simple::QueryExecutor

Inherits:
Object
  • Object
show all
Defined in:
lib/voruby/simple/sap.rb

Overview

Executes a series of queries, each in its own thread. Typical use might be something like this:

# Convert the query results into an object representation.
objectifier = Proc.new { |query|
   query.marshall().votable().votable()
}

# Prepare a SIAP query
nsa_siap = Simple::ImageAccess.new('http://archive.noao.edu/nvo/sim/voquery.php',
	         '23:00:00, 2:00:00', 7, nil, 30, 'rexml')

# Prepare a SSAP query
iso_ssap = Simple::SpectralAccess.new('http://pma.iso.vilspa.esa.es:8080/aio/jsp/siap.jsp',

‘53.084, -27.873’, 10, => ‘votable’, 30, ‘rexml’)

# Prepare a cone search query
mast_cone = Simple::ConeSearch.new('http://archive.stsci.edu/hst/search.php',

53.084, -27.873, 0.01, nil, 30, ‘rexml’)

# Execute the queries asynchronously.
Simple::QueryExecutor.new([nsa_siap, iso_ssap, mast_cone], objectifier).results().each do |query, votable|
  # Just to prove things are working, output the list of field UCDs for each table.
  puts "#{query.to_s()}..."
  votable.fields().each do |field|
    puts "#{field.id()}, #{field.name()}, #{field.ucd().value() if field.ucd() != nil}"
  end

  votable.rows().each do |row|
    puts row
  end

  puts "\n"
end

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(queries = [], converter = Proc.new{|qo| qo}, abort_on_exception = false) ⇒ QueryExecutor

queries:

A list of valid query objects. Good examples of these are:

  • Simple::SpectralAccess (Simple Spectral Access Protocol queries)

  • Simple::ImageAccess (Simple Image Access Protocol queries)

  • Simple::ConeSearch (Simple Cone Search queries)

converter:

An anonymous subroutine that can be used to convert the result of a query into another form–often a VOTABLE::VOTable for our purposes. By default, it simply returns the completed query.

abort_on_exeception:

A flag which indicates whether or not if one query fails, the other queries should abort, too.

Each query must also have a fetch method. One way to get this is to mixin the Simple::HTTPGetQuery module.



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# File 'lib/voruby/simple/sap.rb', line 57

def initialize(queries=[], converter=Proc.new{|qo| qo}, abort_on_exception=false)
  @queries = queries
  @converter = converter
  Thread::abort_on_exception = abort_on_exception
    
  @results = {}
  begin_queries()
end

Instance Attribute Details

#converter ⇒ Object

Returns the value of attribute converter.



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# File 'lib/voruby/simple/sap.rb', line 40

def converter
  @converter
end

#queries ⇒ Object

Returns the value of attribute queries.



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# File 'lib/voruby/simple/sap.rb', line 40

def queries
  @queries
end

#results ⇒ Object (readonly)

Returns the value of attribute results.



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# File 'lib/voruby/simple/sap.rb', line 41

def results
  @results
end

Instance Method Details

#begin_queries ⇒ Object

Kick off each query into its own thread.



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# File 'lib/voruby/simple/sap.rb', line 67

def begin_queries
  threads = []

  # Place each query in its own thread.
  queries.each do |query|
  threads << Thread.new(query){ |the_query|
	  the_query.fetch()
	  # Convert the query into something (maybe itself).
	  @results[the_query] = converter.call(the_query)
  }
  end

  # Make sure each thread finishes before the program
  # exits.
  threads.each{ |thread| thread.join() }
end