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Call MongoDB function from Java

I'm trying to call a stored JavaScript function from the MongoDB Java driver.
I have been following this guide to store the function on the DB server and I'm able to call the function from the mongo shell and have the result returned.
However I cannot figure out how to call the same function in Java?
According to this http://api.mongodb.org/java/current/com/mongodb/DB.html#doEval-java.lang.String-java.lang.Object...- there's a method called doEval
I have also tried to use it with this method:
public static String callFunction() {
try (MongoClient client = new MongoClient("localhost")) {
com.mongodb.DB db = client.getDB("TestDB");
return db.doEval("echoFunction", 3).toString();
}
}
But when I call the method this is what I get:
{ "retval" : { "$code" : "function (x) {\n return x;\n}"} , "ok" : 1.0}
and I would expect to get the number 3 back in this case.
Another problem with the above code is that the method client.getDB() is deprecated. As I understand it the new method to call is client.getDatabase() and it returns a MongoDatabase object, but according to the API there is no method to execute a function.
So my question is: Is it possible to execute a stored JavaScript function on the database server from Java and get back the result of that function? And if it is possible, I would appreciate some help on how to do it?
Thank you.
Edit:
According to a comment on Calling server js function on mongodb from java:
"It seems like getNextSequence is a function written in the mongo
javascript shell. Neither the database (mongod) nor the Java side
knows this function exists and neither is able to interprete the
Javascript code the function contains. You will have to reimplement it
in Java. "
The function I'm trying to implement is a bit more complex than the example above - it's supposed to return a collection of documents and that does not seems to be working using the db.doEval method.
So I guess the comment is correct?

You can do all this with java driver.
MongoClient mongoClient = new MongoClient();
MongoDatabase mdb = mongoClient.getDatabase("TestDB");
/* run this <code snippet> in bootstrap */
BsonDocument echoFunction = new BsonDocument("value",
new BsonJavaScript("function(x1) { return x1; }"));
BsonDocument myAddFunction = new BsonDocument("value",
new BsonJavaScript("function (x, y){ return x + y; }"));
mdb.getCollection("system.js").updateOne(
new Document("_id", "echoFunction"),
new Document("$set", echoFunction),
new UpdateOptions().upsert(true));
mdb.getCollection("system.js").updateOne(
new Document("_id", "myAddFunction"),
new Document("$set", myAddFunction),
new UpdateOptions().upsert(true));
mdb.runCommand(new Document("$eval", "db.loadServerScripts()"));
/* end </code snippet> */
Document doc1 = mdb.runCommand(new Document("$eval", "echoFunction(5)"));
System.out.println(doc1);
The result is also:
Document{{retval=5.0, ok=1.0}}

You should do this instead:
return db.doEval("echoFunction(3)").toString();
If you use just function name in eval you only refer to JavaScript variable on server side storing code of function. It doesn't execute it. When you use parentheses you request to actually execute a function. If you need to send something more complex than a number I would advise to use JSON serializer.

I resolved the same issue in the following way:
I run a command in mongoShell to create my stored JavaScript functions:
db.system.js.save(
{
_id: "echoFunction" ,
value : function(x1) { return x1; }
}
)
db.system.js.save(
{
_id : "myAddFunction" ,
value : function (x, y){ return x + y; }
}
);
db.system.js.save(
{
_id: "fullFillCollumns" ,
value : function () {
for (i = 0; i < 2000; i++) {
db.numbers.save({num:i}); } }
}
);
To execute this functions from MongoDB Java Driver:
MongoClient mongoClient = new MongoClient();
MongoDatabase db = mongoClient.getDatabase("databaseName");
db.runCommand(new Document("$eval", "fullFillCollumns()"));
Document doc1 = db.runCommand(new Document("$eval", "echoFunction(5)"));
System.out.println(doc1);
Document doc2 = db.runCommand(new Document("$eval", "myAddFunction(5,8)"));
System.out.println(doc2);
I see that the collection numbers were created and filled with values. In the IntellijIdea console I see:
Document{{retval=5.0, ok=1.0}}
Document{{retval=13.0, ok=1.0}}

Ingest(Update hash Code) in echoprint servers using JAVA

I am developing an android application using JAVA. All I want is to
record a song and generate its hash(CODE), then query the echoprint server for a match.
If a match is not found, then upload it to the server (ingest) for future references.
I have been able to achieve the first part. Can someone suggest me about the second part in JAVA? (P.S. : I've seen how to do it using python codes - but that won't be helpful in my case.)
Another question, may I achieve the second objective with the global echoprint server? Or, do I need to set up one of my own?
The references I've used are:
http://masl.cis.gvsu.edu/2012/01/25/android-echoprint/
https://github.com/gvsumasl/EchoprintForAndroid

To insert a song into the echoprint server database, all you need to do is call the ingest method. Basically, it is only a HTTP POST request with correct json body. Here is a Scala code (Java would be very similar) that I am using for that:
import EasyJSON.JSON
import EasyJSON.ScalaJSON
import dispatch.Defaults.executor
import dispatch._
class EchoprintAPI {
val API_URL = "http://your.api.server"
def queryURL(code: String) = url(s"$API_URL/query?fp_code=$code")
def query(code: String): scala.concurrent.Future[ScalaJSON] = {
jsonResponse(queryURL(code))
}
def ingest(json: ScalaJSON, trackId: String): scala.concurrent.Future[ScalaJSON] = {
val metadata = json("metadata")
val request = url(s"$API_URL/ingest").POST
.addParameter("fp_code", json("code").toString)
.addParameter("artist", metadata("artist").toString)
.addParameter("release", metadata("release").toString)
.addParameter("track", metadata("title").toString)
.addParameter("codever", metadata("version").toString)
.addParameter("length", metadata("duration").toString)
.addParameter("genre", metadata("genre").toString)
.addParameter("bitrate", metadata("bitrate").toString)
.addParameter("source", metadata("filename").toString)
.addParameter("track_id", trackId)
.addParameter("sample_rate", metadata("sample_rate").toString)
jsonResponse(request)
}
def delete(trackId: String): scala.concurrent.Future[ScalaJSON] = {
jsonResponse(url(s"$API_URL/query?track_id=$trackId").DELETE)
}
protected def jsonResponse(request: dispatch.Req): scala.concurrent.Future[EasyJSON.ScalaJSON] = {
val response = Http(request OK as.String)
for (c <- response) yield JSON.parseJSON(c)
}
}
To generate the fingerprint code, you can use echoprint-codegen command line call or use the Java JNI integration with C lib

MongoDB SELF JOIN query having 1 collection

I'd like to do something like
SELECT e1.sender
FROM email as e1, email as e2
WHERE e1.sender = e2.receiver;
but in MongoDB. I found many forums about JOIN, which can be implemented via MapReduce in MongoDB, but I don't understand how to do it in this example with self-join.
I was thinking about something like this:
var map1 = function(){
var output = {
sender:db.collectionSender.email,
receiver: db.collectionReceiver.findOne({email:db.collectionSender.email}).email
}
emit(this.email, output);
};
var reduce1 = function(key, values){
var outs = {sender:null, receiver:null
values.forEach(function(v) {
if(outs.sender == null){
outs.sender = v.sender
}
if(outs.receivers == null){
outs.receiver = v.receiver
}
});
return outs; }};
db.email.mapReduce(map2,reduce2,{out:'rec_send_email'})
to create 2 new collections - collectionReceiver containing only receiver email and collectionSender containing only sender email
OR
var map2 = function(){
var output = {sender:this.sender,
receiver: db.email.findOne({receiver:this.sender})}
emit(this.sender, output);
};
var reduce2 = function(key, values){
var outs = {sender:null, receiver:null
values.forEach(function(v){
if(outs.sender == null){
outs.sender = v.sender
}
if(outs.receiver == null){
outs.receiver = v.receiver
}
});
return outs; };};
db.email.mapReduce(map2,reduce2,{out:'rec_send_email'})
but none of them is working and I don't understand this MapReduce-thing well. Could somebody explain it to me please? I was inspired by this article http://tebros.com/2011/07/using-mongodb-mapreduce-to-join-2-collections/ .
Additionally, I need to write it in Java. Is there any way how to solve it?

If you need to implement a "self-join" when using MongoDB then you may have structured your schema incorrectly (or sub-optimally).
In MongoDB (and noSQL in general) the schema structure should reflect the queries you will need to run against them.
It looks like you are assuming a collection of emails where each document has one sender and one receiver and now you want to find all senders who also happen to be receivers of email? The only way to do this would be via two simple queries, and not via map/reduce (which would be far more complex, unnecessary and the way you've written them wouldn't work as you can't query from within map function).
You are writing in Java - why not make two queries - the first to get all unique senders and the second to find all unique receivers who are also in the list of senders?
In the shell it would be:
var senderList = db.email.distinct("sender");
var receiverList = db.email.distinct("receiver", {"receiver":{$in:senderList}})

Android-Magento- How to Get the Details of Multiple Products in Android using XML-RPC

How to get the details of Multiple products in a Single Call in Android using XMLRPC from Magento.I am able to get the list of products using the function catalog_product.list using XMLRPC.
Now, i have the SKU id's of all the products.I am able to get the media details of each product using the function product_media.list.
If suppose I have 10 products,i have to call 10 times product_media.list method for each product which takes long time.
So,how can I call the multiCall function of Magento in Android. Many tutorials in php for calling the multiCall function are posted but I am not able to imitate the same in Android.
So please help me if you have similar code snippet that can make me understand multiCall function(for Android) so that I can Advance further using that.
Thanks.
PHP code Example from Josua Marcel C 's Answer:
$session = $client->call('login', array('apiUser', 'apiKey'));
$client->call('call', array($session,'somestuff.method', array('arg1', 'arg2', 'arg3')));
$client->call('call', array($session, 'somestuff.method', 'arg1'));
$client->call('call', array($session, 'somestuff.method'));
$client->call('multiCall',
array($session,
array(
array('somestuff.method', 'arg1'),
array('somestuff.method', array('arg1', 'arg2')),
array('somestuff.method')
)
)
);
I would like to imitate the above php code in Android that calls the multiCall() function of the Magento.

After making long long Research, I got half-way Solution that calls the multiCall() method without any Error,but Still I don't know how to get the response of the Server in a variable and use it.
AnyOne who has knowledge of it can Edit my Answer, I will be thankful to him.
The Code that I have Used is :
Object[] skuid=new Object[product_list.size()];
Object calling[]=new Object[product_list.size()];
for(int m=0;m<product_list.size();m++)
{
skuid[m]=new Object[]{product_list.get(m).getp_Sku()};
calling[m]=new Object[]{"catalog_product_attribute_media.list",skuid[m]};
}
try
{
client.callEx("multiCall",new Object[]{Utils.sessionId,calling});
}
catch (XMLRPCException e)
{
e.printStackTrace();
}
AcknowledgeMents :
I have worked on the Answer posted by Iain.

The Answer
since android is based java application, You can use this.
package org.apache.xmlrpc;
import java.util.Hashtable;
import java.util.Vector;
public class MultiCall
implements ContextXmlRpcHandler
{
public Object execute(String method, Vector params, XmlRpcContext context)
throws Exception
{
if ("multicall".equals(method))
{
return multicall(params, context);
}
throw new NoSuchMethodException("No method '" + method + "' in " + this.getClass().getName());
}
public Vector multicall(Vector requests, XmlRpcContext context)
{
// The array of calls is passed as a single parameter of type array.
requests=(Vector)requests.elementAt(0);
Vector response = new Vector();
XmlRpcServerRequest request;
for (int i = 0; i < requests.size(); i++)
{
try
{
Hashtable call = (Hashtable) requests.elementAt(i);
request = new XmlRpcRequest((String) call.get("methodName"),
(Vector) call.get("params"));
Object handler = context.getHandlerMapping().getHandler(request.getMethodName());
Vector v = new Vector();
v.addElement(XmlRpcWorker.invokeHandler(handler, request, context));
response.addElement(v);
}
catch (Exception x)
{
String message = x.toString();
int code = (x instanceof XmlRpcException ?
((XmlRpcException) x).code : 0);
Hashtable h = new Hashtable();
h.put("faultString", message);
h.put("faultCode", new Integer(code));
response.addElement(h);
}
}
return response;
}
}
Source
Since Magento support SOAP API why didn't you use SOAP API v1? because SOAP is powerful. try to go here What's the difference between XML-RPC and SOAP?
Parsing of Soap messages is not included in Android runtime, so it isn't really straightforward. You should use an external library. I'm using ksoap2.
If you search here on StackOverflow you'll see many examples on how to use it. For instance here
more references: link 1 link 2
MultiCall with PHP
$client = new Zend_XmlRpc_Client('http://magentohost/api/xmlrpc/');
// If somestuff requires api authentification,
// we should get session token
$session = $client->call('login', array('apiUser', 'apiKey'));
$client->call('call', array($session, 'somestuff.method', array('arg1', 'arg2', 'arg3')));
$client->call('call', array($session, 'somestuff.method', 'arg1'));
$client->call('call', array($session, 'somestuff.method'));
$client->call('multiCall', array($session,
array(
array('somestuff.method', 'arg1'),
array('somestuff.method', array('arg1', 'arg2')),
array('somestuff.method')
)
));
// If you don't need the session anymore
$client->call('endSession', array($session));

First login in whatever way works for calling catalog_product.list. Make sure session, client and product_ids have the right values. If you don't need to log in for these operations, set session = null (and if that doesn't work, try not passing session at all :) ). Then:
Object[][] calls = new Object[product_ids.length];
for (int i = 0; i < product_ids.length; i++) {
calls[i] = new Object[] { "product_media.list", product_ids[i] };
}
product_media_ids = client.call("multiCall", new Object[] { session, calls });
product_media_ids should then be an array of arrays of product images - that is, each element of product_media_ids will be a return value from product_media.list.
The code is untested, I'm afraid.

Riak ReferenceError - with custom javascript

i am playing around a litle with riak an the riak-java-client.
Now i run into trouble with custom javascript, i want to use in a map reduce query.
If i use the pure javascript functions as anon functions, they work well.
So here is what i did:
uncommented in app.conf
{js_source_dir, "/tmp/js_source"},
then i stored mylib.js in /tmp/js_source
/* content of mylib.js */
var NS = (function() {
return {
mapHighValues: function(value, keydata, arg) {
var data = JSON.parse(value.values[0].data);
ejsLog('/tmp/map_reduce.log', JSON.stringify(data.High));
return [data.High];}
},
reduceSumHighValues: function(values) {
ejsLog('/tmp/map_reduce.log', "ReduceVals\n" + JSON.stringify(values));
return [values.reduce(function(prev, curr, index, array) {return prev + curr} ,0)];
}
}
})();
after that i restarted riak.
Here is the relevant java code:
MapReduceBuilder builder = new MapReduceBuilder(new RiakClient("localhost"))
.setBucket("goog")
.map(JavascriptFunction.named("NS.mapHighValues"), false)
.reduce(JavascriptFunction.named("NS.reduceSumHighValues"), true);
MapReduceResponseSource response = builder.submit();
Does anyone see my mistake?
Cheers
ApeHanger

Looks like an extra '}' after 'return [data.High];'