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Query » History » Revision 28

Revision 27 (Chengyu Fan, 07/16/2015 02:34 PM) → Revision 28/29 (Chengyu Fan, 09/05/2015 08:19 AM)

# Catalog Query API 

 Catalogs feature an NDN name-based query API to enable discovery. 


 ## Query Request 

 Catalog queries are expressed as a JSON <query-parameters> Interest name component: 

     /<prefix>/query/<query-parameters> 

 Query parameters simultaneously support two types of queries: 

 1. component type-based 
 2. absolute prefix-based 

 The requestor will encode query parameters as a JSON object, with the format: <tt>{[field1]=[search1],[field2]=[search2],?=[search3]</tt>} where <tt>field1</tt> and <tt>field2</tt> are Name components. <tt>?</tt> indicates an absolute prefix-based autocomplete search where <tt>search3</tt> is the prefix. <i>(See [[Schema]])</i> 

 ### Query Parameters Schema 


 ``` 

 { 
     "$schema": "http://json-schema.org/draft-04/schema#", 
     "title": "catalog query", 
     "type": "object", 
     "items": { 
         "title": "query parameters", 
         "type": "object", 
         "properties": { 
             "name": { 
                 "type": "string" 
             }, 
             "activity": { 
                 "type": "string" 
             }, 
             "product": { 
                 "type": "string" 
             }, 
             "organization": { 
                 "type": "string" 
             }, 
             "model": { 
                 "type": "string" 
             }, 
             "experiment": { 
                 "type": "string" 
             }, 
             "frequency": { 
                 "type": "string" 
             }, 
             "modeling realm": { 
                 "type": "string" 
             }, 
             "variable name": { 
                 "type": "string" 
             }, 
             "ensemble member": { 
                 "type": "string" 
             }, 
             "ensemble": { 
                 "type": "string" 
             }, 
             "sample granularity": { 
                 "type": "string" 
             }, 
             "start time": { 
                 "type": "string" 
             }, 
             "field campaign": { 
                 "type": "string" 
             }, 
             "optical properties for radiation": { 
                 "type": "string" 
             }, 
             "grid resolution": { 
                 "type": "string" 
             }, 
             "output type": { 
                 "type": "string" 
             }, 
             "timestamp": { 
                 "type": "string" 
             }, 
             "?": { 
                 "description": "Autocomplete search field" 
                 "type": "string" 
             } 
         }, 
         "required": [] 
     } 
 } 

 ``` 


 ## Query Results 

 Catalogs answer queries with one or more Query Result Data packets. Each packet contains a JSON list of matching NDN name URIs 
 Query responses are Data containing a JSON list of matching name URIs. Each packet is named according to: 

     /<prefix>/query-results/<catalog-id>/<query-parameters>/<version>/<segmentNumber> /<prefix>/query-results/<query-parameters>/<version>/<catalog-id>/<segmentNumber> 

 The response set is versioned and uniquely identifies the catalog that produced it (e.g. identity key digest). 

 ### Query Results Data JSON 


 ``` 
 { 
     "$schema": "http://json-schema.org/draft-04/schema#", 
     "title": "Catalog Query Result", 
     "type": "array", 
     "items": { 
         "title": "QueryResults", 
         "type": "object", 
         "properties": { 
             "resultCount": { 
                "description": "The total number of the records in query results" 
                "type": unsigned integer 
             }, 
             "results": { 
                "description": "List of NDN name URIs" 
                "type": Array 
             }, 
             "next": { 
                 "description": "Autocomplete search potential next field(s)" 
                 "type": Array 
             } 
         }, 
         "required": [resultCount] 
     }, 
    
 } 
 ```