datasource.js

datasource.js

Is an Ajax Database Connectivity (ADBC) layer. Provides data access support for various data sources (SQL, SPARQL, SOAP, etc.) and allows binding and execution of callbacks upon data arrival. Data are fetched on demand and cached.

Objects

OAT.DataSource(type)

Creates new DataSource object.typeis one of TYPE_constants.

Properties

OAT.DataSource::connection

Assigns an OAT.Connection object to this DataSource.

OAT.DataSource::options

Object with various properties, dependent on DataSource TYPE_: * TYPE_SQL

• query - SQL query
• limit - cursor limit
• cursortype - 0/1; 0 - snapshot, 1 - dynaset
• TYPE_SOAP
• service - name of WSDL service
• rootelement - name of root input WSDL element
• inputobj - input WSDL object (see ws.js documentation for details)
• TYPE_REST , TYPE_SPARQL , TYPE_GDATA
• query - HTTP GET querystring
• output - 0/1; 0 - xml, 1 = json
• xpath - bool; how are outputFields specified? True = XPath expressions; False = node names

OAT.DataSource::outputFields

List of wanted fields in fetched data.

Methods

OAT.DataSource::bindRecord(recordCallback)

Listens for new data records. When new record is available, recordCallback is executed with 2 arguments: record data and record index.

OAT.DataSource::bindPage(pageCallback)

Listens for new data record pages. When new data page (record set) is available, pageCallback is executed with 2 arguments:page data and page index.

OAT.DataSource::bindFile(fileCallback)

Listens for new data file. When new data file is available, fileCallback is executed with 1 argument: file contents.

OAT.DataSource::bindEmpty(emptyCallback)

Listens for empty dataset. When empty dataset arrives, emptyCallback is executed.

OAT.DataSource::bindHeader(headerCallback)

Listens for data header. When header arrives, headerCallback is executed with 1 argument: data header.

OAT.DataSource::advanceRecord(recordIndex)

Advances through records.recordIndex must be an integer.

Constants

OAT.DataSourceData.TYPE_SQL

OAT.DataSourceData.TYPE_SOAP

OAT.DataSourceData.TYPE_REST

OAT.DataSourceData.TYPE_SPARQL

OAT.DataSourceData.TYPE_GDATA

Examples

REST Example

var conn = new OAT.Connection(OAT.ConnectionData.TYPE_REST, {url:"myfile.xml"});

var ds = new OAT.DataSource(OAT.DataSourceData.TYPE_REST);
ds.connection = conn;
ds.options.output = 0; /* fetch result as XML */
ds.options.xpath = 1; /* outputFields are specified as XPATH expressions */
ds.outputFields = ['//result/binding[@name="created"]/node()/text()',
                                        '//result/binding[@name="creator"]/node()/text()',
                                        '//result/binding[@name="item_title"]/node()/text()',
                                        '//result/binding[@name="url"]/node()/text()'];

var recordCallback = function(data, index) {
        alert('Data at index ' + index + ':\n' + data );
}
ds.bindRecord(recordCallback);
ds.advanceRecord(0);

SQL Example

var conn = new OAT.Connection(OAT.ConnectionData.TYPE_XMLA, {dsn:"DSN=Local_Instance",endpoint:"/XMLA"});

var ds = new OAT.DataSource(OAT.DataSourceData.TYPE_SQL);
ds.connection = conn;
ds.options.query = "SELECT OrderID, CustomerID, EmployeeID FROM Demo.demo.Orders";

var recordCallback = function(data, index) {
        alert('Data at index ' + index + ':\n' + data );
}
ds.bindRecord(recordCallback);
ds.advanceRecord(0);

SPARQL Example

var connection = new OAT.Connection(OAT.ConnectionData.TYPE_REST,{url:"/sparql/"});
var q = "SELECT ?s, ?p, ?o FROM <http://www.flickr.com/search/?q=rdf+semanticweb&s=rec> WHERE { ?s ?p ?o . }";

var ds = new OAT.DataSource(OAT.DataSourceData.TYPE_SPARQL);
ds.outputFields = ['//result/binding[@name="s"]/node()/text()',
   '//result/binding[@name="p"]/node()/text()',
   '//result/binding[@name="o"]/node()/text()'];

ds.connection = connection;
ds.options.query = "query="+encodeURIComponent(q)+"&format=xml";
ds.options.output = 0; /* fetch result as XML */
ds.options.xpath = 1; /* outputFields are specified as XPATH expressions */

var recordCallback = function(data, index) {
        alert('Data at index ' + index + ':\n' + data );
}
ds.bindRecord(recordCallback);
ds.advanceRecord(0);

GData Example

var conn = new OAT.Connection(OAT.ConnectionData.TYPE_REST, {url:"gdata.xml"});

var ds = new OAT.DataSource(OAT.DataSourceData.TYPE_GDATA);
ds.connection = conn;
ds.options.output = 0;
ds.options.xpath = 1;
ds.outputFields = [ "//atom:feed/atom:entry/atom:title" ];

var recordCallback = function(data, index) {
        alert('Data at index ' + index + ':\n' + data );
}

ds.bindRecord(recordCallback);
ds.advanceRecord(0);