how get JSON from URL - xpages

Question

I need to read with the function SSJS fromJson() a URL.
For example the Data access API for a Notes View
http://{host}/{database}/api/data/collections/name/{name}
How can I do this ?
P.S I think (I don't know if is true) that if I use Java code
(for example the class URLReader from this blogger, I
lose authors/readers functionality because is my server and not the current user that execute the reading of the stream?
I'll explain why I'm trying to understand this...
I need to use this plugin JQuery Jquery Data Tables in my app.
I need a complete Server-side processing because I have over 10.000 documents for any view.
This jQueryPlugin send a parameters to a specif URL (I think my XAgent) so that I think to create a XAgent that read this parameter and parsing a JSON API Data for the output.
This because I need a fasted response.
The solution of Oliver Busse it very slow because load all entries of my view in a JSON (I have many entries) and I wait 30/40 seconds for this operation

Answer 1

I gather from the PS that you're specifically looking to fetch JSON on the server from itself, while retaining user authentication information. Sven's post there does a bit of that, but I think that the most reliable way would be to grab the Authorization and Cookie headers from the request and then pass them along in your URL request. This answer has a good basis for doing this with Java. You could expand that to do something like this (which, granted, I haven't tested, but it's a starting point):
HttpServletRequest req = (HttpServletRequest)FacesContext.getCurrentInstance().getExternalContext().getRequest();
String authorization = req.getHeader("Authorization");
String cookie = req.getHeader("Cookie");
URL myURL = new URL("http://foo.com");
HttpURLConnection myURLConnection = (HttpURLConnection)myURL.openConnection();
if(StringUtil.isNotEmpty(authorization)) {
myURLConnection.setRequestProperty("Authorization", authorization);
}
if(StringUtil.isNotEmpty(cookie)) {
myURLConnection.setRequestProperty("Cookie", cookie);
}
myURLConnection.setRequestMethod("GET");
myURLConnection.setDoInput(true);
myURLConnection.setDoOutput(true);
myURLConnection.connect();
InputStream is = null;
try {
is = myURLConnection.getInputStream();
String result = StreamUtil.readString(is);
} finally {
StreamUtil.close(is);
myURLConnection.disconnect();
}
Ideally, you would also fetch the server host name, protocol, and port from the request.
Eric's comment is also wise: if this is something you can do with the normal classes, that's going to be more flexible and less problem-prone, due to how fiddly server-self HTTP calls can be.

Answer 2

As I mentioned in my comment, this approach forces that your call go through a client-side call to the Domino Data Service and otherwise complicates a normal handle to establish on a View (and it's contents) via a cross-NSF call (e.g.- var vwEnt:ViewEntryCollection = session.getDatabase("serverName", "path/myDb.nsf").getView("viewName").getAllEntries();).
As a blog post of mine previously outlines, you can definitely achieve this as Jesse's answer (curse you fast typer Jesse!) outlines. Something I include in my "grab bag" of tools is a Java class that's a starting point for getting JSON formatted content. Here's the link (here's one with basic authorization in a request header) and the class I generally start from:
package com.eric.awesome;
import java.net.URL;
import java.net.URLConnection;
import java.io.BufferedReader;
import com.google.gson.*;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
import java.net.MalformedURLException;
import org.apache.commons.validator.routines.*;
/**
* Class with a single, public, static method to provide a REST consumer
* which returns data as a JsonObject.
*
* #author Eric McCormick, #edm00se
*
*/
public class CustJsonConsumer {
/**
* Method for receiving HTTP JSON GET request against a RESTful URL data source.
*
* #param myUrlStr the URL of the REST endpoint
* #return JsonObject containing the data from the REST response.
* #throws IOException
* #throws MalformedURLException
* #throws ParseException
*/
public static JsonObject GetMyRestData( String myUrlStr ) throws IOException, MalformedURLException {
JsonObject myRestData = new JsonObject();
try{
UrlValidator defaultValidator = new UrlValidator();
if(defaultValidator.isValid(myUrlStr)){
URL myUrl = new URL(myUrlStr);
URLConnection urlCon = myUrl.openConnection();
urlCon.setConnectTimeout(5000);
InputStream is = urlCon.getInputStream();
InputStreamReader isR = new InputStreamReader(is);
BufferedReader reader = new BufferedReader(isR);
StringBuffer buffer = new StringBuffer();
String line = "";
while( (line = reader.readLine()) != null ){
buffer.append(line);
}
reader.close();
JsonParser parser = new JsonParser();
myRestData = (JsonObject) parser.parse(buffer.toString());
return myRestData;
}else{
myRestData.addProperty("error", "URL failed validation by Apache Commmons URL Validator");
return myRestData;
}
}catch( MalformedURLException e ){
e.printStackTrace();
myRestData.addProperty("error", e.toString());
return myRestData;
}catch( IOException e ){
e.printStackTrace();
myRestData.addProperty("error", e.toString());
return myRestData;
}
}
}
To invoke from SSJS as a POJO, you would want do something like:
importPackage(com.eric.awesome);
var urlStr = "http://{host}/{database}/api/data/collections/name/{name}";
var myStuff:JsonObject = CustJsonConsumer.GetMyRestData(urlStr);