Querying Dbpedia from Sesame from behind a proxy/firewall

Question

Hi People, How do you query DBPedia using sesame's SparqlRepository Class?

I am able to get it to work in the absence of a proxy. But unfortunately I am behind a proxy in office and am not able to hit it.

Get a Connect Exception.

Any solution? Thanks in Advance :)

Edit: http://sourceforge.net/mailarchive/forum.php?thread_name=7767F3FDF9BF194A9DDDD22719FD3FF523BE82307B%40ZEUS.cefriel.it&forum_name=sesame-general

Found a Link that gives an answer to this. A source code change is required apparently.

Weird ain't it? anybody else faced a similar problem?? if so did you get around to solving it??

Edit: tried with it with the following code

Tried it .....couldn't get it to work at all....

System.getProperties().put("http.proxyHost", "someproxy");

System.getProperties().put("http.proxyPort", "someport");

System.getProperties().put("http.proxyUser", "myId");

System.getProperties().put("http.proxyPassword", "password");

String endpointURL = "http://dbpedia.org/sparql";

dbpediaEndpoint = new HTTPRepository(endpointURL, "");

dbpediaEndpoint.initialize();

conn = dbpediaEndpoint.getConnection();

String sparqlQuery = " SELECT ?X ?P ?Y WHERE {?X ?P ?Y}";

TupleQuery query = conn.prepareTupleQuery(QueryLanguage.SPARQL,

sparqlQuery); TupleQueryResult result = query.evaluate(); // do something linked and open

Doesn't want to connect :(

Am i doing something wrong?

Answer 1

You can configure HTTP proxy settings for Sesame using Java system properties. The following properties are relevant:

http.proxyHost should be set to the host name of your proxy.
http.proxyPort should be set to the proxy port number.
http.proxyUser (optional) should be set to a username to identify yourself at the proxy.
http.proxyPassword (optional) should be set to a password to identify yourself at the proxy.

Unfortunately, this currently only works for HTTPRepository, the SPARQLRepository class currently does not consider these options (this is being worked on).

However, you should be able to use the HTTPRepository class for accessing DBPedia via SPARQL in place of the SPARQLRepository. It's not normally the recommended way, but it will work. Just use the DBPedia SPARQL endpoint url as if it were a Sesame repository url. SPARQL querying will work, but most other API operations will fail.

Edit The way you are setting system properties is incorrect. Instead, use something like this:

System.setProperty("http.proxyHost", hostname);
//... etc for other properties

Or, of course, set them at runtime using java -Dhttp.proxHost=hostname -D... .

Querying Dbpedia from Sesame from behind a proxy/firewall

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