Methods
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Session#fetch
This function can take any number of arguments. Each argument can be a string or a TopicSelector. Alternatively, an array of strings and TopicSelectors can be passed as a single argument.(selector)
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Fetch the current state of one or more topics.
Fetching a topic will provide its current value without subscribing this client to that topic. The returned FetchStream will emit
value
events for each topic that is matched for which a fetch request can be satisfied. Once complete, the FetchStream will be closed.Parameters:
Name Type Description selector
String | TopicSelector | Array.<String> The topic selector to fetch
Returns:
A FetchStream that will emit the fetched values.
- Type
- FetchStream
Examples
// Fetch a topic's value session.fetch("foo").on('value', function(value, path) { console.log("Value for topic '" + path + "' is: " + value); });
// Fetch multiple topics, handling possible errors session.fetch("?foo/bar.*").on({ value : function(value, path) { ... }, error : function(error) { ... }, close : function() { ... } });
Type Definitions
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CloseReason
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Type:
- Object
Properties:
Name Type Description id
Number unique id
message
String message with further details
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Field
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Properties:
Name Type Description scale
Number the scale of a decimal field
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Node
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Properties:
Name Type Description Node.name
String the node name
Node.min
Number the minimum number of occurences of the node within its parent
Node.max
Number the maximum number of occurences of the node within its parent
Node.isVariable
Boolean if the node has variable multiplicity, or has fixed multiplicity, i.e min != max
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Record
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Properties:
Name Type Description Record.fields
Array.<Field> a list of the field definitions. There will be at least one