Class: OMF::Web::DataSourceProxy

Inherits:
Base::LObject
  • Object
show all
Defined in:
lib/omf-web/data_source_proxy.rb

Overview

This object maintains synchronization between a JS DataSource object in a web browser and the corresponding OmlTable in this server.

Constant Summary collapse

@@datasources = 
{}

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, data_source) ⇒ DataSourceProxy

Returns a new instance of DataSourceProxy.



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# File 'lib/omf-web/data_source_proxy.rb', line 181

def initialize(name, data_source)
  @name = name
  @data_source = data_source
end

Instance Attribute Details

#data_source ⇒ Object (readonly)

Returns the value of attribute data_source.



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# File 'lib/omf-web/data_source_proxy.rb', line 119

def data_source
  @data_source
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/omf-web/data_source_proxy.rb', line 119

def name
  @name
end

Class Method Details

.[](name) ⇒ Object 



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# File 'lib/omf-web/data_source_proxy.rb', line 43

def self.[](name)
  find(name)
end

.find(name, warn_if_not_exist = true) ⇒ Object 



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# File 'lib/omf-web/data_source_proxy.rb', line 47

def self.find(name, warn_if_not_exist = true)
  name = name.to_sym
  unless dsp = OMF::Web::SessionStore[name, :dsp]
    if ds = @@datasources[name]
      dsp = OMF::Web::SessionStore[name, :dsp] = self.new(name, ds)
    else
      if warn_if_not_exist
        warn "Requesting unknown datasource '#{name}', only know about '#{@@datasources.keys.join(', ')}'."
      end
    end
  end
  dsp
end

.for_source(ds_descr) ⇒ Object

Return proxies for ‘ds_name’. Note, there can be more then one proxy be needed for a datasource, such as a network which has one ds for the nodes and one for the links

@return: Array of proxies

TODO: This seems to hardcode networks.



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# File 'lib/omf-web/data_source_proxy.rb', line 83

def self.for_source(ds_descr)
  #raise "FOO #{ds_descr.inspect}"
  unless ds_descr.is_a? Hash
    raise "Expected Hash, but got '#{ds_descr.class}::#{ds_descr.inspect}'"
  end
  unless ds_name = ds_descr[:name]
    raise "Missing 'name' attribute in datasource description. (#{ds_descr.inspect})"
  end
  ds_name = ds_name.to_sym
  ds = @@datasources[ds_name]
  unless ds
    top = "#{ds_name}/"
    names = @@datasources.keys.find_all { |ds_name| ds_name.to_s.start_with? top }
    unless names.empty?
      return names.map do |ds_name|
        OMF::Web::SessionStore[ds_name, :dsp] ||= self.new(ds_name, @@datasources[ds_name])
      end
    end
    unless ds
      raise "Unknown data source '#{ds_name}' (#{@@datasources.keys.inspect})"
    end
  end
  if ds.is_a? Hash
    raise "Is this actually used anywhere?"
    proxies = ds.map do |name, ds|
      id = "#{ds_name}_#{name}".to_sym
      proxy = OMF::Web::SessionStore[id, :dsp] ||= self.new(id, ds)
    end
    return proxies
  end

  #debug ">>>>> DS: #{ds_descr.inspect} - #{ds}"
  proxy = OMF::Web::SessionStore[ds_name, :dsp] ||= self.new(ds_name, ds)
  return [proxy]
end

.register_datasource(data_source, opts = {}) ⇒ Object

A data_source needs to support eh following methods:

* rows Returns an array of rows
* on_content_changed(lambda{action, rows}) Call provided block with actions :added, :removed
* create_sliced_table (optional)
* release Not exactly sure when that is being used
* schema Schema of row
* offset



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# File 'lib/omf-web/data_source_proxy.rb', line 32

def self.register_datasource(data_source, opts = {})
  name = (opts[:name] || data_source.name).to_sym
  if (@@datasources.key? name)
    raise "Repeated try to register data source '#{name}'"
  end
  if data_source.is_a? OMF::OML::OmlNetwork
    raise "Register link and node table separately "
  end
  @@datasources[name] = data_source
end

.validate_ds_description(ds_descr) ⇒ Object 



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# File 'lib/omf-web/data_source_proxy.rb', line 61

def self.validate_ds_description(ds_descr)
  debug "Validate datasource - #{ds_descr}"
  unless ds_descr.is_a? Hash
    raise "Expected Hash, but got '#{ds_descr.class}::#{ds_descr.inspect}'"
  end
  return true if ds_descr[:data_url] # We can fetch the data in the browser if necessary
  unless ds_name = ds_descr[:id] || ds_descr[:stream] || ds_descr[:name]
    raise "Missing 'name' attribute in datasource description. (#{ds_descr.inspect})"
  end
  ds_name = ds_name.to_sym
  ds = @@datasources[ds_name]
  ds != nil
end

Instance Method Details

#create_slice(col_name, col_value) ⇒ Object

Create a new data source which only contains a slice of the underlying data source



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# File 'lib/omf-web/data_source_proxy.rb', line 150

def create_slice(col_name, col_value)
  ds = @data_source.create_sliced_table(col_name, col_value)
  dsp = self.class.new(ds.name, ds)
  def dsp.release; @data_source.release end
  dsp
end

#on_changed(offset, &block) ⇒ Object

Register callback to be informed of changes to the underlying data source. Call block when new rows are becoming available. Block needs ot return true if it wants to continue receiving updates.

offset: Number of records already downloaded



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# File 'lib/omf-web/data_source_proxy.rb', line 136

def on_changed(offset, &block)
  ds = @data_source
  rows = ds.rows[(offset - ds.offset) .. -1]
  if rows && rows.length > 0
    debug "on_changed: sending #{rows.length}"
    block.call :added, rows
  end
  @data_source.on_content_changed(block.object_id) do |action, rows|
    #debug "on_changed: #{action}: #{rows.inspect}"
    block.call action, rows
  end
end

#on_update(req) ⇒ Object 



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# File 'lib/omf-web/data_source_proxy.rb', line 125

def on_update(req)
  res = {:events => @data_source.rows}
  [res.to_json, "text/json"]
end

#reset ⇒ Object 



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# File 'lib/omf-web/data_source_proxy.rb', line 121

def reset()
  # TODO: Figure out partial sending
end

#to_hash(opts = {}) ⇒ Object 



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# File 'lib/omf-web/data_source_proxy.rb', line 157

def to_hash(opts = {})
  sid = Thread.current["sessionID"]
  opts = opts.dup
  opts[:name] ||= @name
  opts[:id] = @name
  opts[:stream] = @name # TODO: Should retire. Code should use :id
  opts[:schema] = @data_source.schema.describe
  opts[:update_url] ||= "/_update/#{@name}?sid=#{sid}"
  opts[:ws_url] ||= "/_ws?sid=#{sid}"
  opts[:sid] = sid
  unless opts[:slice] # don't send any data if this is a sliced one
    opts[:rows] = []
    opts[:offset] = @data_source.offset
  end
  opts
end

#to_javascript(opts = {}) ⇒ Object 



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# File 'lib/omf-web/data_source_proxy.rb', line 174

def to_javascript(opts = {})
  opts = to_hash(opts)
  %{
    ds.register(#{opts.to_json});
  }
end