Develop Reference

Connect To MongoDB using Apache Mahout

I'm trying to generate recommendations using Apache Mahout while using MongoDB to create the datamodel as per the MongoDBDataModel. My code is as follows :
import java.net.UnknownHostException;
import java.util.List;
import org.apache.mahout.cf.taste.common.TasteException;
import org.apache.mahout.cf.taste.impl.model.mongodb.MongoDBDataModel;
import org.apache.mahout.cf.taste.impl.neighborhood.ThresholdUserNeighborhood;
import org.apache.mahout.cf.taste.impl.recommender.GenericItemBasedRecommender;
import org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender;
import org.apache.mahout.cf.taste.impl.similarity.PearsonCorrelationSimilarity;
import org.apache.mahout.cf.taste.neighborhood.UserNeighborhood;
import org.apache.mahout.cf.taste.recommender.RecommendedItem;
import org.apache.mahout.cf.taste.recommender.UserBasedRecommender;
import org.apache.mahout.cf.taste.similarity.ItemSimilarity;
import org.apache.mahout.cf.taste.similarity.UserSimilarity;
import com.mongodb.MongoException;
public class usingMongo {
public static void main(String[] args) throws UnknownHostException, Mong oException
,TasteException {
final long startTime = System.nanoTime();
MongoDBDataModel model = new MongoDBDataModel("AdamsLaptop", 27017,
"test", "ratings100k", false, false, null);
System.out.println("connected to mongo ");
UserSimilarity UserSim = new PearsonCorrelationSimilarity(model);
UserNeighborhood neighborhood = new ThresholdUserNeighborhood(0.5, UserSim, model);
UserBasedRecommender UserRecommender = new GenericUserBasedRecommender(model, neighborhood, UserSim);
List<RecommendedItem>UserRecommendations = UserRecommender.recommend(1, 3);
for (RecommendedItem recommendation : UserRecommendations) {
System.out.println("You may like movie " + recommendation.getItemID() + " as a user similar to you also rated it " + recommendation.getValue() + " USER");
}
ItemSimilarity ItemSim = new PearsonCorrelationSimilarity(model);//LogLikelihoodSimilarity(model);
GenericItemBasedRecommender ItemRecommender = new GenericItemBasedRecommender(model, ItemSim);
List<RecommendedItem>ItemRecommendations = ItemRecommender.recommend(1, 3);
for (RecommendedItem recommendation : ItemRecommendations) {
System.out.println("You may like movie " + recommendation.getItemID() + " as a user similar to you also rated it " + recommendation.getValue() + " ITEM");
}
final long duration = System.nanoTime() - startTime;
System.out.println(duration);
}
}
I cant see where I've gone wrong but with numerous changes and lots of trial and error the error message remains the same :
Exception in thread "main" java.lang.NullPointerException
at org.apache.mahout.cf.taste.impl.model.mongodb.MongoDBDataModel.getID(MongoDBDataModel.java:743)
at org.apache.mahout.cf.taste.impl.model.mongodb.MongoDBDataModel.buildModel(MongoDBDataModel.java:570)
at org.apache.mahout.cf.taste.impl.model.mongodb.MongoDBDataModel.<init>(MongoDBDataModel.java:245)
at recommender.usingMongo.main(usingMongo.java:24)
Any suggestions? Here's an example of my data within MongoDB :
{ "_id" : ObjectId("56ddf61f5960960c333f3dcb"),"userId" : 1, "movieId" : 292, "rating" : 4, "timestamp" : 847116936 }

I succesfully integrated MongoDB data to mahout.
The structure of the data in mongoDB depends on the kind of Similarity algorithm you use.for eg,
UserSimilarity
MongoDBDataModel datamodel = new MongoDBDataModel("127.0.0.1", 27017, "testing", "ratings", true, true, null);
where the user_id, item_id are integer values, preference are float values and created_at as timestamp
SVDRecommender
the user_id, item_id are MongoDB Objects and preference are float values and created_at as timestamp
The obvious troubleshooting you can do is whether the MongoDB server is running or not. As per the exception it's running. I think the problem lies in your structure of data..
Use user_id instead of userId, item_id instead of itemId, preference instead of rating. I don't know if this will make any difference. I used one of the tutorial online, but can't find it at the moment.
It's working but too slow when I have more than 10000 users with 1000 items.

I think that the problem is that mahout assumes some default values when it comes to some fields that need to reside in your mongoDB the item ID, User ID and preferences that are user_id, item_id and preference so The solution might lie on using another MongoDBDataModel constructor that will give you the possibility to pass as parameters the names of those fields in your mongoDB instance or redesign your Collections Schema.
I hope that makes sense.

Finding product in category

I need to find products in different categories on eBay. But when I use the tutorial code
ebay.apis.eblbasecomponents.FindProductsRequestType request = new ebay.apis.eblbasecomponents.FindProductsRequestType();
request.setCategoryID("Art");
request.setQueryKeywords("furniture");
I get the following error: QueryKeywords, CategoryID and ProductID cannot be used together.
So how is this done?
EDIT: the tutorial code is here.
EDIT2: the link to the tutorial code died, apparently. I've continued to search and the category cannot be used with the keyword search, but there's a Domain that you could presumably add to the request, but sadly it's not in the API - so I'm not sure if indeed it can be done.
The less-than-great eBay API doc is here.
This is my full request:
Shopping service = new ebay.apis.eblbasecomponents.Shopping();
ShoppingInterface port = service.getShopping();
bp = (BindingProvider) port;
bp.getRequestContext().put(BindingProvider.ENDPOINT_ADDRESS_PROPERTY, endpointURL);
// Add the logging handler
List<Handler> handlerList = bp.getBinding().getHandlerChain();
if (handlerList == null) {
handlerList = new ArrayList<Handler>();
}
LoggingHandler loggingHandler = new LoggingHandler();
handlerList.add(loggingHandler);
bp.getBinding().setHandlerChain(handlerList);
Map<String,Object> requestProperties = bp.getRequestContext();
Map<String, List<String>> httpHeaders = new HashMap<String, List<String>>();
requestProperties.put(BindingProvider.ENDPOINT_ADDRESS_PROPERTY, endpointURL);
httpHeaders.put("X-EBAY-API-CALL-NAME", Collections.singletonList(CALLNAME));
httpHeaders.put("X-EBAY-API-APP-ID", Collections.singletonList(APPID));
httpHeaders.put("X-EBAY-API-VERSION", Collections.singletonList(VERSION));
requestProperties.put(MessageContext.HTTP_REQUEST_HEADERS, httpHeaders);
// initialize WS operation arguments here
FindProductsRequestType request = new FindProductsRequestType();
request.setAvailableItemsOnly(true);
request.setHideDuplicateItems(true);
request.setMaxEntries(2);
request.setPageNumber(1);
request.setQueryKeywords("Postcard");
request.setDomain("");
The last line, which should set the domain like I need to, does not compile. Any idea how to solve this?
EDIT 3: I gave up on the Java API and I'm doing direct REST. The categories on eBay are actually domains now, and the URL looks like this:
String findProducts = "http://open.api.ebay.com/shopping?callname=FindProducts&responseencoding=XML&appid=" + APPID
+ "&siteid=0&version=525&"
+ "&AvailableItemsOnly=true"
+ "&QueryKeywords=" + keywords
+ "&MaxEntries=10"
+ "&DomainName=" + domainName;
This works, but you want to hear a joke? It seems like not all the domains are listed here and so it doesn't really solve this problem. Pretty disappointing work by eBay.

The solution for finding items based on keywords, in a category, is to use findItemsAdvanced. Could have saved me a lot of time if the docs for FindProducts stated this, instead of just saying that you can use either keyword search OR category search.
This is the API URL:
http://open.api.ebay.com/shoppingcallname=findItemsAdvanced&responseencoding=XML&appid=" + APPID
+ "&siteid=0&version=525&"
+ "&AvailableItemsOnly=true"
+ "&QueryKeywords=" + keywords
+ "&categoryId=" + categoryId
+ "&MaxEntries=50
For completion, if you want to get a list of all the top categories you can use this:
http://open.api.ebay.com/Shopping?callname=GetCategoryInfo&appid=" + APPID + "&siteid=0&CategoryID=-1&version=729&IncludeSelector=ChildCategories

Java JPA EclipseLink ManyToMany INSERT

I have the following ManyToMany association within my Project:
Class User:
#ManyToMany(cascade=CascadeType.ALL)
#JoinTable(
joinColumns={#JoinColumn(name="user_id")},
inverseJoinColumns={#JoinColumn(name="antrag_id")}
)
private List<Antrag> antraege;
And Class Antrag:
#ManyToMany(mappedBy="antraege",cascade=CascadeType.ALL)
private List<User> users;
I am trying to correctly insert a new record, this - I think works not correctly. When I'm trying to "reselect" all Antraege of User, I am getting a NullPointerException on antraege.getUsers(). Only when I restart the java swing application, antraege.getUsers() doesn't return null.
Code for Inserting my new ManyToMany record:
Antrag antrag = new Antrag();
antrag.setBetreff(betreff);
antragBusiness.create(antrag);
betreuer.getAntraege().add(antrag);
currentUser.getAntraege().add(antrag);
userBusiness.update(betreuer);
userBusiness.update(currentUser);
Where my create method uses persist and the update method uses merge.
As I've said, they get inserted correctly into the database, but when I try to call:
List<Antrag> antraege = (List<Antrag>) user.getAntraege();
for(Antrag a : antraege){
News n = new News();
n.setDatum(a.getCreatedAt());
n.setStatus(a.isStatus());
n.setThema(a.getInfo());
List<User> beteiligte = a.getUsers();
System.out.println("Amount users " + beteiligte.size());
for (User z : beteiligte) {
System.out.println(z.getNachname() + " " + z.getId());
if(z.getId() != user.getId()){
n.setZustaendiger(z);
}
}
newsList.add(n);
}
-> Amount users returns 0 :(
So - in consequences: Antraege are added to Users, but users not to Antraege?
Edit: As it seems, my insertion of a new ManyToMany record is not correct.
Can anyone explain me the correct way ?

Is it possible to get a list of workflows the document is attached to in Alfresco

I'm trying to get a list of workflows the document is attached to in an Alfresco webscript, but I am kind of stuck.
My original problem is that I have a list of files, and the current user may have workflows assigned to him with these documents. So, now I want to create a webscript that will look in a folder, take all the documents there, and assemble a list of documents together with task references, if there are any for the current user.
I know about the "workflow" object that gives me the list of workflows for the current user, but this is not a solution for my problem.
So, can I get a list of workflows a specific document is attached to?

Well, for future reference, I've found a way to get all the active workflows on a document from javascript:
var nodeR = search.findNode('workspace://SpacesStore/'+doc.nodeRef);
for each ( wf in nodeR.activeWorkflows )
{
// Do whatever here.
}

I used packageContains association to find workflows for document.
Below i posted code in Alfresco JavaScript for active workflows (as zladuric answered) and also for all workflows:
/*global search, logger, workflow*/
var getWorkflowsForDocument, getActiveWorkflowsForDocument;
getWorkflowsForDocument = function () {
"use strict";
var doc, parentAssocs, packages, packagesLen, i, pack, props, workflowId, instance, isActive;
//
doc = search.findNode("workspace://SpacesStore/8847ea95-108d-4e08-90ab-34114e7b3977");
parentAssocs = doc.getParentAssocs();
packages = parentAssocs["{http://www.alfresco.org/model/bpm/1.0}packageContains"];
//
if (packages) {
packagesLen = packages.length;
//
for (i = 0; i < packagesLen; i += 1) {
pack = packages[i];
props = pack.getProperties();
workflowId = props["{http://www.alfresco.org/model/bpm/1.0}workflowInstanceId"];
instance = workflow.getInstance(workflowId);
/* instance is org.alfresco.repo.workflow.jscript.JscriptWorkflowInstance */
isActive = instance.isActive();
logger.log(" + instance: " + workflowId + " (active: " + isActive + ")");
}
}
};
getActiveWorkflowsForDocument = function () {
"use strict";
var doc, activeWorkflows, activeWorkflowsLen, i, instance;
//
doc = search.findNode("workspace://SpacesStore/8847ea95-108d-4e08-90ab-34114e7b3977");
activeWorkflows = doc.activeWorkflows;
activeWorkflowsLen = activeWorkflows.length;
for (i = 0; i < activeWorkflowsLen; i += 1) {
instance = activeWorkflows[i];
/* instance is org.alfresco.repo.workflow.jscript.JscriptWorkflowInstance */
logger.log(" - instance: " + instance.getId() + " (active: " + instance.isActive() + ")");
}
}
getWorkflowsForDocument();
getActiveWorkflowsForDocument();

Unfortunately the javascript API doesn't expose all the workflow functions. It look like getting the list of workflow instances that are attached to a document only works in Java (or Java backed webscripts).
List<WorkflowInstance> workflows = workflowService.getWorkflowsForContent(node.getNodeRef(), true);
A usage of this can be found in the workflow list in the document details: http://svn.alfresco.com/repos/alfresco-open-mirror/alfresco/HEAD/root/projects/web-client/source/java/org/alfresco/web/ui/repo/component/UINodeWorkflowInfo.java
To get to the users who have tasks assigned you would then need to use getWorkflowPaths and getTasksForWorkflowPath methods of the WorkflowService.

Google Appengine - Object with id "com.google.appengine.api.datastore.Key:Product("Potatoe")" is managed by a different Object Manager

Hi i am hitting the common error "managed by a different object manager"
I have looked around online and not found a solution that fits my problem. I am calling the following code from a JSP page
PersistenceManager pm = PMF.get().getPersistenceManager();
String query = "SELECT FROM " +Location.class.getName();
List<Location> locTs = (List<Location>) pm.newQuery(query).execute();
for (Location location : locTs) {
location.genRes(pm);
}
pm.close();
return "done";
location.genRes
public void genRes(PersistenceManager pm) {
Key product = this.getLtype(pm).getProductKey();
String query = "SELECT FROM " + LocationInventry.class.getName() + " WHERE location == '"+key.getId()+"' && product == '"+product.getId()+"'";
List<LocationInventry> lvd = (List<LocationInventry>) pm.newQuery(query).execute();
if (lvd.size() == 0 ) {
LocationInventry locationInventry = new LocationInventry(product, this);
pm.makePersistent(locationInventry);
}
else {
lvd.get(0).gen();
}
}
The error is being thrown on pm.makePersistent(locationInventry);
As far as I can tell I am using only one persistent management and I am closing it after use. Thanks for any help.
Object with id "com.google.appengine.api.datastore.Key:Product("Potatoe")" is managed by a different Object Manager
org.datanucleus.jdo.NucleusJDOHelper.getJDOExceptionForNucleusException(NucleusJDOHelper.java:375)
org.datanucleus.jdo.JDOPersistenceManager.jdoMakePersistent(JDOPersistenceManager.java:674)
org.datanucleus.jdo.JDOPersistenceManager.makePersistent(JDOPersistenceManager.java:694)
net.sparktank.quilage.datastore.Location.genRes(Location.java:220)
net.sparktank.quilage.server.MainRunner.genResources(MainRunner.java:239)
org.apache.jsp.server.generateResources_jsp._jspService(generateResources_jsp.java:45)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:94)
javax.servlet.http.HttpServlet.service(HttpServlet.java:806)

I had this same problem some time ago and I have a vague memory that my jdoconfig.xml file was missing or not configured correctly.
Check out http://code.google.com/appengine/docs/java/datastore/usingjdo.html for more details.