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  • How to get faster graphics in KVM? VNC is painfully slow with Haiku OS guest, Spice won't install and SDL doesn't work

    - by Don Quixote
    I've been coming up to speed on the Haiku operating system, an Open Source clone of BeOS 5 Pro. I'm using an Apple MacBook Pro as my development machine. Apple's BootCamp BIOS does not support more than four partitions on the internal hard drive. While I can set up extended and logical partitions, doing so will prevent any of the installed operating systems from booting. To run Haiku directly on the iron, I boot it off a USB stick. Using external storage is also helpful because I am perpetually out of filesystem space. While VirtualBox is documented to allow access to physical drives, I could not actually get it to work. Also VirtualBox can only use one of the host CPU's cores. While VB guests can be configured for more than one CPU, they are only emulated. A full build of the Haiku OS takes 4.5 under VB. I had the hope of reducing build times by using KVM instead, but it's not working nearly as well as VirtualBox did. The Linux Kernel Virtual Machine is broken in all manner of fundamental ways as seen from Haiku. But I'm a coder; maybe I could contribute to fixing some of those problems. The first problem I've got is that Haiku's video in virt-manager is quite painfully slow. When I drag Haiku windows around the desktop, they lag quite far behind where my mouse is. It's quite difficult to move a window to a precise position on the screen. Just imagine that the mouse was connected to the window title bar with a really stretchy spring. Also Haiku's mouse lags quite far behind where I have moved it. I found lots of Personal Package Archives that enable Spice from QEMU / KVM at the Ubuntu Personal Package Arhives. I tried a few of the PPAs but none of them worked; with one of them, the command "add-apt-repository" crashed with a traceback. There is a Wiki page about Spice, but it says that it only works on 64-bit. My Early 2006 MacBook Pro is 32-bit. Its Apple Model Identifier is MacBookPro1,1; these use Core Duos NOT Core 2 Duos. I don't mind building a source deb for 32-bit if I can expect it to work. Is there some reason that Spice should be 64-bit only? Does it need features of the x86_64 Instruction Set Architecture that x86 does not have? When I try using SDL from virt-manager, the configuration for Local SDL Window says "Xauth: /home/mike/.Xauthority". When I try to start my guest, virt-manager emits an error. When I Googled the error message, the usual solution was to make ~/.Xauthority readible. However, .Xauthorty does not exist in my home directory. Instead I have a $XAUTHORITY environment variable. There is no way to configure SDL in virt-manager to use $XAUTHORITY instead of ~/.Xauthority. Neither does it work to copy the value of $XAUTHORITY into the file. I am ready to scream, because I've been five fscking days trying to make KVM work for Haiku development. There is a whole lot more that is broken than the slow video. All I really want to do for now is speed up my full builds of Haiku by using "jam -j2" to use both cores in my CPU. I may try Xen next, but the last time I monkeyed with Xen it was far, far more broken than I am finding KVM to be. Just for now, I would be satisfied if there were some way to use my USB stick as a drive in VirtualBox. VB does allow me to configure /dev/sdb as a drive, but it always causes a fatal error when I try to launch the guest. Thank You For Any Advice You Can Give Me. -

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  • Virtualized data centre&ndash;Part three: Architecture

    - by marc dekeyser
    Having the basics (like discussed in the previous articles) is all good and well, but how do we get started on this?! It can be quite daunting after all!   From my own point of view I can absolutely confirm your worries and concerns, but also tell you that it is not as hard as it seems! Deciding on what kind of motherboard to buy, processor and how much memory is an activity you will spend quite some time doing research on. And that is not even mentioning storage! All in all it comes down to setting you expectations and your budget. Probably adjusting your expectations according to your budget :). Processors As a rule of thumb you want VT-D (virtualization) technology built in to the processor allowing you to have 64 bit machines running on your host. Memory The more the better! If you are building a home lab don’t bother with ECC unless you are going to run machines that absolutely should be on all the time and your comfort depends on it! Motherboard Depends on what you are going to do with storage: If you are going the NAS way then the number of SATA port/RAID capabilities do not really matter. If you decide to have a single server with lots of dedicated storage it obviously matters how much SATA ports you will have, alternatively you could use a RAID controller (but these set you back a pretty penny if you want one. DELL 6i’s are usually available for a good bargain if you can find one!). Easiest is to get one with a built-in graphics card (on-board) as you are just adding more heat, power usage and possible points of failure. Networking Just like your choice of motherboard the networking side tends to depend on how you want to go. A single virtualization  host with local storage can usually get away with having a single network card, a cluster or server which uses iSCSI storage tends to have more than one teamed up :). Storage The dreaded beast from the dark! The horror which lives in the forest! The most difficult decision you are going to make in the building of your lab. Why you might ask? Simple my friend, having the right choice of storage can make or break your virtualization solution. The performance of you storage choice will have an important impact on the responsiveness of your virtual machines and the deployment of new machines. It also makes a run with your budget! If you decide to go the NAS route you will be dropping a lot more money than if you would be having just a bunch of disks sitting in a server and manually distributing the virtual machines over the disks. Platform I’m a Microsoftee so Hyper-V is a dead giveaway for me. If you are interested in using VMware I won’t stop you but the rest of my posts will be oriented on Server 2012 Hyper-V (aka 3.0)! What did I use? Before someone asks me this in the comments I’ll give you a quick run down of what I am using. - Intel 2.4 quad core processors (i something something) - 24 GB DDR3 Memory - Single disk in each server (might look at this as I move the servers to 2012) - Synology DS1812+ NAS - 3 network interfaces where possible - HP1800 procurve managed switch I decided to spring for the NAS as I will also be using it for backups and media storage (which is working out quite nicely with my Xbox 360 I must say). At the time of building my 2 boxes (over a year and a half ago) these set me back about 900 euros each so I can image you can build the same or better for a lower price. Next article will be diagramming what I want to achieve and starting a build on the Hyper V 3.0 cluster!

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  • I am trying to figure out the best way to understand how to cache domain objects

    - by Brett Ryan
    I've always done this wrong, I'm sure a lot of others have too, hold a reference via a map and write through to DB etc.. I need to do this right, and I just don't know how to go about it. I know how I want my objects to be cached but not sure on how to achieve it. What complicates things is that I need to do this for a legacy system where the DB can change without notice to my application. So in the context of a web application, let's say I have a WidgetService which has several methods: Widget getWidget(); Collection<Widget> getAllWidgets(); Collection<Widget> getWidgetsByCategory(String categoryCode); Collection<Widget> getWidgetsByContainer(Integer parentContainer); Collection<Widget> getWidgetsByStatus(String status); Given this, I could decide to cache by method signature, i.e. getWidgetsByCategory("AA") would have a single cache entry, or I could cache widgets individually, which would be difficult I believe; OR, a call to any method would then first cache ALL widgets with a call to getAllWidgets() but getAllWidgets() would produce caches that match all the keys for the other method invocations. For example, take the following untested theoretical code. Collection<Widget> getAllWidgets() { Entity entity = cache.get("ALL_WIDGETS"); Collection<Widget> res; if (entity == null) { res = loadCache(); } else { res = (Collection<Widget>) entity.getValue(); } return res } Collection<Widget> loadCache() { // Get widgets from underlying DB Collection<Widget> res = db.getAllWidgets(); cache.put("ALL_WIDGETS", res); Map<String, List<Widget>> byCat = new HashMap<>(); for (Widget w : res) { // cache by different types of method calls, i.e. by category if (!byCat.containsKey(widget.getCategory()) { byCat.put(widget.getCategory(), new ArrayList<Widget>); } byCat.get(widget.getCatgory(), widget); } cacheCategories(byCat); return res; } Collection<Widget> getWidgetsByCategory(String categoryCode) { CategoryCacheKey key = new CategoryCacheKey(categoryCode); Entity ent = cache.get(key); if (entity == null) { loadCache(); } ent = cache.get(key); return ent == null ? Collections.emptyList() : (Collection<Widget>)ent.getValue(); } NOTE: I have not worked with a cache manager, the above code illustrates cache as some object that may hold caches by key/value pairs, though it's not modelled on any specific implementation. Using this I have the benefit of being able to cache all objects in the different ways they will be called with only single objects on the heap, whereas if I were to cache the method call invocation via say Spring It would (I believe) cache multiple copies of the objects. I really wish to try and understand the best ways to cache domain objects before I go down the wrong path and make it harder for myself later. I have read the documentation on the Ehcache website and found various articles of interest, but nothing to give a good solid technique. Since I'm working with an ERP system, some DB calls are very complicated, not that the DB is slow, but the business representation of the domain objects makes it very clumsy, coupled with the fact that there are actually 11 different DB's where information can be contained that this application is consolidating in a single view, this makes caching quite important.

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  • Maven error: Unable to get resource / Server redirected too many times

    - by tewe
    Our proxy went down and I tried to update dependencies with maven while it was off. Since then I can't download anything with maven. I get this error for everything. I tried -U option, deleting my local repository and tried different maven version (2.0.9, 2.2.1) but it doesn't work. Any idea how to solve this? Earlier it also said 'repository will be blacklisted' to all of them. Downloading: http://repo1.maven.org/maven2/org/apache/maven/plugins/maven-compiler-plugin/2.1/maven-compiler-plugin-2.1.pom [WARNING] Unable to get resource 'org.apache.maven.plugins:maven-compiler-plugin:pom:2.1' from repository central (http://repo1.maven.org/maven2): Error transferring file: Server redirected too many times (20) org.apache.maven.plugins:maven-compiler-plugin:pom:2.1 from the specified remote repositories: jboss-snapshot (http://snapshots.jboss.org/maven2), central (http://repo1.maven.org/maven2), JBoss Repo (http://repository.jboss.com/maven2), spring-maven-snapshot (http://maven.springframework.org/snapshot), com.springsource.repository.bundles.external (http://repository.springsource.com/maven/bundles/external), com.springsource.repository.bundles.snapshot (http://repository.springsource.com/maven/bundles/snapshot), jboss (http://repository.jboss.com/maven2), com.springsource.repository.bundles.release (http://repository.springsource.com/maven/bundles/release), jboss-snapshot-plugins (http://snapshots.jboss.org/maven2), com.springsource.repository.bundles.milestone (http://repository.springsource.com/maven/bundles/milestone), jboss-plugins (http://repository.jboss.com/maven2) at org.apache.maven.artifact.resolver.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:228) at org.apache.maven.artifact.resolver.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:90) at org.apache.maven.project.DefaultMavenProjectBuilder.findModelFromRepository(DefaultMavenProjectBuilder.java:558) ... 25 more Caused by: org.apache.maven.wagon.ResourceDoesNotExistException: Unable to download the artifact from any repository at org.apache.maven.artifact.manager.DefaultWagonManager.getArtifact(DefaultWagonManager.java:404) at org.apache.maven.artifact.resolver.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:216) ... 27 more

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  • Most useful free .NET libraries?

    - by Binoj Antony
    I have used a lot of free .NET libraries, some from Microsoft itself! Which ones have you found the most useful? Dependency Injection/Inversion of Control Unity Framework - Microsoft StructureMap - Jeremy Miller Castle Windsor NInject Spring Framework Autofac Managed Extensibility Framework Logging Logging Application Block - Microsoft Log4Net - Apache Error Logging Modules and Handlers(ELMAH) NLog Compression SharpZipLib DotNetZip YUI Compressor (CSS and JS compression/minification) AjaxMinifier (in other downloads) (JS compression. Also includes MSBuild task) Ajax Ajax Control Toolkit - Microsoft AJAXNet Pro Data Mapper XmlDataMapper AutoMapper ORM NHibernate Castle ActiveRecord Subsonic XmlDataMapper Charting/Graphics Microsoft Chart Controls for ASP.NET 3.5 SP1 Microsoft Chart Controls for Winforms ZedGraph Charting NPlot - Charting for ASP.NET and WinForms PDF Creators/Generators PDFsharp iTextSharp Unit Testing/Mocking NUnit Rhino Mocks Moq TypeMock.Net xUnit.net mbUnit Machine.Specifications Automated Web Testing Selenium Watin URL Rewriting url rewriter UrlRewriting.Net Url Rewriter and Reverse Proxy - Managed Fusion Controls Krypton - Free winform controls Source Grid - A Grid control Devexpress - free controls Unclassified CSLA Framework - Business Objects Framework AForge.net - AI, computer vision, genetic algorithms, machine learning Enterprise Library 4.1 - Logging, Exception Management, Validation, Policy Injection File helpers library C5 Collections - Collections for .NET Quartz.NET - Enterprise Job Scheduler for .NET Platform MiscUtil - Utilities by Jon Skeet Lucene.net - Text indexing and searching Json.NET - Linq over JSON Flee - expression evaluator PostSharp - AOP IKVM - brings the extensive world of Java libraries to .NET. Title of the question taken from here. [EDIT] Please provide links to these free libraries as well. Once we have a huge list of this, it can be arranged in categories! Please do not mention .NET Applications/EXEs here.

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  • eclipse tomcat debug mode slow - pegs cpu

    - by andersonbd1
    Running Tomcat through eclipse works fine in non-debug mode, but not in debug mode. When I try to start the Tomcat server in debug mode, the console output looks fine for a while, but then starts slowing down and eventually just stops, pegging the cpu at 100%. I don't think it's relevant, but just in case - here's the console output right about when it starts slowing down and eventually stopping (by stopping I mean no more console output, but still 100% cpu). 2009-09-02 14:35:30,859 INFO NONE org.springframework.context.weaving.DefaultContextLoadTimeWeaver:72 - Found Spring's JVM agent for instrumentation 2009-09-02 14:35:49,562 INFO NONE org.springframework.beans.factory.support.DefaultListableBeanFactory:414 - Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@ed889d: defining beans [... 2009-09-02 14:37:31,031 INFO NONE org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean:221 - Building JPA container EntityManagerFactory for persistence unit ... I tried everything I could think of to fix it: cleanesd tomcat working directory restarted eclipse restarted Windows refreshed/cleaned all projects I first had this problem last week using eclipse ganymede. I had been running fine in debug-mode for several months prior to this issue. I didn't make any significant changes to our project that would cause this. Eventually, I upgraded to eclipse galileo which solved my problem. Now 2 days later, I'm having the same problem in galileo. Like I said it works fine in non-debug mode. Any help is much appreciated. I should add that other things work in debug mode - for instance junit tests, so it is something specific to tomcat.

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  • Error 404: No target servlet configured for uri

    - by Aman
    Hi Experts, I just got done with a new Web module built with Spring Framework. Till now I was testing all the pages on my local machine using Tomcat. Today after I moved the application to Websphere, I am getting the following error: Error 404: No target servlet configured for uri is there anything I need to do in web.xml or somewhere? I deployed an EAR file on my WAS , which has another war file. Below is the output I am seeing on the console, if thats any help. The resource WEB-INF/ibm-web-bnd.xmi that is defined in URI WEB-INF/ibm-web-bnd.xmi for module analytics.war is not valid. The resource has a cross reference org.eclipse.jst.j2ee.webapplication.internal.impl.WebAppImpl@4be44be4 (eProxyURI: WEB-INF/web.xml#WebApp_ID) that cannot be resolved. [6/17/09 15:24:49:465 CDT] 00000011 ArchiveDeploy W ADMA0091E: The resource WEB-INF/ibm-web-ext.xmi that is defined in URI WEB-INF/ibm-web-ext.xmi for module analytics.war is not valid. The resource has a cross reference org.eclipse.jst.j2ee.webapplication.internal.impl.WebAppImpl@7b7a7b7a (eProxyURI: WEB-INF/web.xml#WebApp_ID) that cannot be resolved.

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  • Android RestTemplate Ok on emulator but fails on real device

    - by Hossein
    I'm using spring RestTemplate and it works perfect on emulator but if I run my app on real device I get HttpMessageNotWritableException ............ nested exception is java.net.SocketException: Broken pipe Here is some lines of my code(keep in mind my app works perfect on emulator) ............ LoggerUtil.logToFile(TAG, "url is [" + url + "]"); LoggerUtil.logToFile(TAG, "NetworkInfo - " + connectivityManager.getActiveNetworkInfo()); ResponseEntity<T> responseEntity = restTemplate.exchange(url, HttpMethod.POST, requestEntity, clazz); ............. I know my device's network works perfect because all other applications on my device are working and also using device browser I'm able to connect to my server so my server is available. My server is up and running and my device is able to connect to my server so why I get java.net.SocketException: Broken pipe ?!!!!!!! Before I call restTemplate.exchange() I log NetworkInfo and it looks ok -type: WIFI -status: CONNECTED/CONNECTED -isAvailable: true Thanks in advance. Update: It is really weird Even if I use HttpURLConnection, it works perfectly on emulator but on real device I get 400 Bad Request Here is my code HttpURLConnection con = null; try { String url = ....; LoggerUtil.logToFile(TAG, "url [" + url + "]" ); con = (HttpURLConnection) new URL(url).openConnection(); con.setRequestMethod("POST"); con.setRequestProperty("Connection", "Keep-Alive"); con.setDoInput(true); con.setDoOutput(true); con.setUseCaches(false); con.connect(); LoggerUtil.logToFile(TAG, "con.getResponseCode is " + con.getResponseCode()); LoggerUtil.logToFile(TAG, "con.getResponseMessage is " + con.getResponseMessage()); } catch(Throwable t){ LoggerUtil.logToFile(TAG, "*** failed [" + t + "]" ); } in log file I see con.getResponseCode is 400 con.getResponseMessage is Bad Request

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  • JPA/JDO entity to XML XSD generator.

    - by h2g2java
    I am using JDO or JPA on GAE plugin in Eclipse. I am using smartgwt datasource, accepting an xsd. I would like to be educated how to generate an XSD from my jdo/jpa entity, vice versa. Is there a tool to do it? While datanucleas does all its magic enhancing in the Eclipse background, would I be able to somehow operate in a mode that would generate XSDs for me? Can Hibernate operate in an offline mode, to solely help me generate XSDs which I could use in GWT without deploying hibernate with my web-app? Can Hibernate even be capable of generating XSDs from entities, vice versa? Currently, I am about to write a utility to generate an xsd, given an entity class - but I am hoping I don't have to reinvent the wheel if it already exists. I am hoping people here could educate me on any available tools to ease my XSD generation. But btw, I am very wary of anything that uses Maven, because most people (like Spring) who write the Maven scripts and pom don't have the expertise to write it in a way that would spew out messages and verbosity appropriately to make it easy for me to locate model errors.

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  • AbstractMethodError when invoking createArrayOf, with postgresql 8.4 jdbc4 and JBoss 5.1GA

    - by Francesco
    Hi, when using this method public List<Field> getFieldWithoutId(List<Integer> idSections) throws Exception { try { Connection conn = this.getConnection(); Array arraySections = conn.createArrayOf("int4", idSections.toArray()); this.log.info("Recupero field"); List<Field> fields = this.getJdbcTemplate().query(getFieldWithoutIdQuery, new Object[] {arraySections},ParameterizedBeanPropertyRowMapper.newInstance(Field.class)); /*if (!conn.isClosed()) conn.close(); */ releaseConnection(conn); return fields; } catch (Exception e) { e.printStackTrace(); throw new Exception("Errore."); } } I have an exception at conn.createArrayOf("int4", idSections.toArray());. The exception is: javax.ejb.EJBException : Unexpected Error java.lang.AbstractMethodError: org.jboss.resource.adapter.jdbc.jdk5.WrappedConnectionJDK5.createArrayOf(Ljava/lang/String;[Ljava/lang/Object;)Ljava/sql/Array; postgresql-8.4-701.jdbc4.jar is in jboss/server/all/lib dir. Application is spring based with ejb3. When working locally with the same setup everything is fine. This only happens on a preproduction environment. Only difference is locally I have jboss run in default mode, in the other case there are 2 jbosses in all configuration. I can't track down the cause of this error. Could someone help me please?

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  • OLAP Web Visualization and Reporting Recommendations

    - by Gok Demir
    I am preparing an offer for a customer. They proide weekly data to different organizations. There is huge amount data suits OLAP that needed to be visualized with charts and pivot tables on web and custom reports will be built by non-it persons (an easy gui). They will enter a date range, location which data columns to be included and generate report and optionally export the data to Excel. They currently prepare reports with MS Excel with Pivot Tables and but they need a better online tool now to show data to their customers. Tables are huge and need of drill-down functionality. My current knowledge Spring, Flex, MySql, Linux. I have some knowledge of PostgreSQL and MSSQL and Windows. What is the easiest way of doing this project. Do you think that SSRP (haven't tried yet) and ASP.NET better suits for this kind of job. Actually I prefer open source solutions. Flex have OLAP Data Grid control which do aggregation on client side. JasperServer seems promising but it seems I need enterprise version (multiple organizations and ad hoc queries). What about Modrian + Flex + PostgreSQL solution? Any previous experience will be appreciated. Yes I am confused with options.

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  • Hibernate not releasing data base connections

    - by cedar715
    Following is the configuration details: <property name="hibernateProperties"> <props> <prop key="hibernate.dialect"> org.hibernate.dialect.Oracle9iDialect </prop> <prop key="hibernate.show_sql">false</prop> <prop key="hibernate.cache.provider_class"> org.hibernate.cache.OSCacheProvider </prop> <prop key="hibernate.cache.use_second_level_cache"> true </prop> <!-- <prop key="hibernate.hbm2ddl.auto">update</prop>--> <!-- HIBERNATE CONNECTION POOLING!!--> <prop key="c3p0.acquire_increment">5</prop> <prop key="c3p0.idle_test_period">100</prop> <!-- seconds --> <prop key="c3p0.max_statements">5</prop> <prop key="c3p0.min_size">15</prop> <prop key="c3p0.max_size">100</prop> <prop key="c3p0.timeout">100</prop> <!-- seconds --> </props> </property> Our application is developed through Spring & Hibernate. Once we bring the application up and hit it, its opening 140 connections and not releasing it. Our DAO looks like this: import org.springframework.orm.hibernate3.support.HibernateDaoSupport; ... public class ActionDAO extends HibernateDaoSupport implements IActionDAO { public Action findById(ActionPK actionPK) { return (Action) getHibernateTemplate().get(Action.class, actionPK); } public void add(Action action) { getHibernateTemplate().save(action); } }

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  • Routing an ActiveMq topic to an external broker.

    - by chillitom
    Hi All, I have an ActiveMq topic which I wish to transform and share with an external broker. At present I have the following which performs the transformation: <camelContext id="camel" xmlns="http://activemq.apache.org/camel/schema/spring"> <route> <from uri="activemq:topic:OriginalTopic"/> <to uri="xslt:file:///xslt/transformation.xsl"/> <to uri="activemq:topic:NewTopic"/> </route> </camelContext> However this just sends the message to the current broker network. I'd like to pass the NewTopic messages to an external broker only. I don't want to join the external broker using a <networkConnector .. > as only this topic should be send to the external broker and no others. Is there a simple way to route messages to an external broker? Many thanks.

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  • Populating JavaScript Array from JSP List

    - by tkeE2036
    Ok so perhaps someone can help me with a problem I'm trying to solve. Essentially I have a JSP page which gets a list of Country objects (from the method referenceData() from a Spring Portlet SimpleFormController, not entirely relevant but just mentioning in case it is). Each Country object has a Set of province objects and each province and country have a name field: public class Country { private String name; private Set<Province> provinces; //Getters and setters } public class Province { private String name; //Getters and setters } Now I have two drop down menus in my JSP for countries and provinces and I want to filter the provinces by country. I've been following this tutorial/guide to make a chain select in JavaScript. Now I need a dynamic way to create the JavaScript array from my content. And before anyone mentions AJAX this is out of the question since our project uses portlets and we'd like to stay away from using frameworks like DWR or creating a servlet. Here is the JavaScript/JSP I have so far but it is not populating the Array with anything: var countries = new Array(); <c:forEach items="${countryList}" var="country" varStatus="status"> countries[status.index] = new Array(); countries[status.index]['country'] = ${country.name}; countries[status.index]['provinces'] = [ <c:forEach items="${country.provinces}" var="province" varStatus="provinceStatus"> '${province.name}' <c:if test="${!provinceStatus.last}"> , </c:if> </c:forEach> ]; </c:forEach> Does anyone know how to create an JavaScript array in JSP in the case above or what the 'best-practice' would be considered in this case? Thanks in advance!

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  • Pros and cons of making database IDs consistent and "readable"

    - by gmale
    Question Is it a good rule of thumb for database IDs to be "meaningless?" Conversely, are there significant benefits from having IDs structured in a way where they can be recognized at a glance? What are the pros and cons? Background I just had a debate with my coworkers about the consistency of the IDs in our database. We have a data-driven application that leverages spring so that we rarely ever have to change code. That means, if there's a problem, a data change is usually the solution. My argument was that by making IDs consistent and readable, we save ourselves significant time and headaches, long term. Once the IDs are set, they don't have to change often and if done right, future changes won't be difficult. My coworkers position was that IDs should never matter. Encoding information into the ID violates DB design policies and keeping them orderly requires extra work that, "we don't have time for." I can't find anything online to support either position. So I'm turning to all the gurus here at SA! Example Imagine this simplified list of database records representing food in a grocery store, the first set represents data that has meaning encoded in the IDs, while the second does not: ID's with meaning: Type 1 Fruit 2 Veggie Product 101 Apple 102 Banana 103 Orange 201 Lettuce 202 Onion 203 Carrot Location 41 Aisle four top shelf 42 Aisle four bottom shelf 51 Aisle five top shelf 52 Aisle five bottom shelf ProductLocation 10141 Apple on aisle four top shelf 10241 Banana on aisle four top shelf //just by reading the ids, it's easy to recongnize that these are both Fruit on Aisle 4 ID's without meaning: Type 1 Fruit 2 Veggie Product 1 Apple 2 Banana 3 Orange 4 Lettuce 5 Onion 6 Carrot Location 1 Aisle four top shelf 2 Aisle four bottom shelf 3 Aisle five top shelf 4 Aisle five bottom shelf ProductLocation 1 Apple on aisle four top shelf 2 Banana on aisle four top shelf //given the IDs, it's harder to see that these are both fruit on aisle 4 Summary What are the pros and cons of keeping IDs readable and consistent? Which approach do you generally prefer and why? Is there an accepted industry best-practice?

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  • @OneToMany and composite primary keys?

    - by Kris Pruden
    Hi, I'm using Hibernate with annotations (in spring), and I have an object which has an ordered, many-to-one relationship which a child object which has a composite primary key, one component of which is a foreign key back to the id of the parent object. The structure looks something like this: +=============+ +================+ | ParentObj | | ObjectChild | +-------------+ 1 0..* +----------------+ | id (pk) |-----------------| parentId | | ... | | name | +=============+ | pos | | ... | +================+ I've tried a variety of combinations of annotations, none of which seem to work. This is the closest I've been able to come up with: @Entity public class ParentObject { @Column(nullable=false, updatable=false) private String id; @OneToMany(mappedBy="object", fetch=FetchType.EAGER) @IndexColumn(name = "pos", base=0) private List<ObjectChild> attrs; ... } @Entity public class ChildObject { @Embeddable public static class Pk implements Serializable { @Column(nullable=false, updatable=false) private String objectId; @Column(nullable=false, updatable=false) private String name; @Column(nullable=false, updatable=false) private int pos; ... } @EmbeddedId private Pk pk; @ManyToOne @JoinColumn(name="parentId") private ParentObject parent; ... } I arrived at this after a long bout of experimentation in which most of my other attempts yielded entities which hibernate couldn't even load for various reasons. The error I get when I try to read one of these objects (they seem to save OK), I get an error of this form: org.hibernate.exception.SQLGrammarException: could not initialize a collection: ... And the root cause is this: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'attrs0_.id' in 'field list' I'm sure I'm missing something simple, but the documentation is not clear on this matter, and I haven't been able to find any examples of this anywhere else. Thanks!

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  • LPX-00607 for ora:contains in java but not sqlplus

    - by Windle
    Hey all, I am trying to doing some sql querys out of Oracle 11g and am having issues using ora:contains. I am using spring's jdbc impl and my code generates the sql statement: select * from view_name where column_a = ? and column_b = ? and existsNode(xmltype(clob_column), 'record/name [ora:contains(text(), "name1") 0]', 'xmlns:ora="http://xmlns.oralce.com/xdb"') = 1 I have removed the actual view / column names obviously, but when I copy that into sqlplus and substitute in random values, the select executes properly. When I try to run it in my DAO code I get this stack trace: org.springframework.jdbc.UncatergorizedSQLException: PreparedStatementCallback; uncatergorizedSQLException for SQL [the big select above]; SQL state [99999]; error code [31011]; ORA-31011: XML parsing failed. ORA-19202: Error occured in XML processing LPX-00607: Invalid reference: 'contains' ;nested exception is java.sql.SQLException: ORA-31011: XML parsing failed ORA-19202: Error occured in XML processing LPX-00607: Invalid reference: 'contains' (continues on like this for awhile....) I think it is worth mentioning that I am using maven and it is possible I am missing some dependency that is required for this. Sorry the post is so long, but I wanted to err on the side of too much info. Thanks for taking the time to read this at least =) -Windle

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  • Maintain order of messages via proxies to app servers

    - by David Turner
    Hi, I am receiving messages from a 3rd party via a http post, and it is important that the order the messages hit our infrastructure is maintained through the load balancers and proxies until it hits our application server. Quick Diagram. (proxies in place due to security requirements.) [ACE load balancer] - [2 proxies] - [Application Servers] or maybe [ACE load balancer] - [2 proxies] - [ACE load balancer] - [Application Servers] My idea was that I would setup the load balancers in active-passive mode, to force all messages to use one proxy, and then both the proxies would hit a second load balancer that would be configured in active passive to hit one application server. Whilst the above is not ideal, it does give me resilience, and once the message is in my app servers, I enter a stateless world, and load balance across both nodes of my cluster. However, I am concerned that even a single proxy could send messages out of order, perhaps if 2 messages are recived very close together, message 2 might get processed faster than message 1. Is this possible? Likely? Is there a simple open source proxy (MOD_PROXY?) that can be easily configured to just pass messages through it, and to guarantee to send the messages through in the order they are received. If so which, and finally links to how I should configure it would be great. In fact any links to articles around avoiding "out of order" messages using hardware would be gratefully received. Thanks, ps for those that are interested, the app is a java spring integration application currently on a appliation server.

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  • Swing data binding frameworks

    - by Ahe
    Hi Almost the same question has been asked a year ago, but the there has been some new development in this area. Selecting a (data binding) framework for swing application seems to be quite difficult. JSR-295 is abandoned, many swing frameworks which provide binding are work-in-progress, abandoned or too heavy for my quite simple app. JGoodies Swing suite is expensive, but luckily its libraries are free. Has anyone any real-world experience of new UFaceKit. It looks promising, but quite immature. I am particularly interested in Swing implementation and documentation. Any insight on UFaceKits development schedule would be appreciated, because I can hold by framework choice for a while. Requirements are not anything fancy, just working binding with a nice API. I also found Mogwai dataBinding, but it seems quite incomplete and requires manual synchronization activation, which makes it useless compared to coarse grained synchronization easily written by hand. Incomplete frameworks include at least Spring RCP and many JSR-296 forks. So, is the JGoodies data binding really the only realistic choice? Or are there any other viable solutions available?

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  • Problem locating file in a classpath

    - by Gandalf StormCrow
    I'm trying to read in file content, ex : public void myMethod(){ FileInputStream fstream = new FileInputStream(fileLocation); // Get the object of DataInputStream DataInputStream in = new DataInputStream(fstream); BufferedReader br = new BufferedReader(new InputStreamReader(in)); String strLine; while ((strLine = br.readLine()) != null) { .... .... ..... end while end method And I have at the begining of the class body private String fileLocation; and at the end of a class I have a getter and setter for it. Now I'm trying inject this file location from spring inside bean from this class and I specify the init-method of this class. But I get error cannot find the specified file as if its not on a classpath but it is inside war file? I'm building the project with maven and I put file in src/main/resources This is the error I get when trying to read file : Error: src\main\resources\ids.txt (The system cannot find the path specified) That is when I tried this : FileInputStream fstream = new FileInputStream("src\\main\\resources\\ids.txt"); how to reference the properly from the classpath? EDIT When I edit my code according to @BalusC solution , here is how it looks but I still get null error : ClassLoader classLoader = Thread.currentThread().getContextClassLoader(); InputStream input = classLoader.getResourceAsStream("src/main/resources/ids.txt"); // Get the object of DataInputStream BufferedReader br = new BufferedReader(new InputStreamReader(input)); String strLine; while ((strLine = br.readLine()) != null) { .... .... ..... end while end method

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  • Grails 1.2.0 not finding plugins in the default repository.

    - by Padraic
    I do not know what changed in my environment, but all of a sudden I can not pull any plugins from the default repository. I went through the _*.groovy scripts and nothing has changed in my grails home directory and it appears that the default repository url is set correctly (DEFAULT_PLUGIN_DIST = "http://plugins.grails.org"). I am assuming it is an environment setting that changed on me, because if I switch to an old version of grails that I have installed, 1.1.1 for example, list-plugins is returning a full list of plugins. When I run grails list-plugins in my current 1.2.0 environment I get the following output: Welcome to Grails 1.2.0 - http://grails.org/ Licensed under Apache Standard License 2.0 Grails home is set to: /opt/grails-1.2.0 Base Directory: /Users/padraic/Projects/TestApplicationMachine Resolving dependencies... Dependencies resolved in 1633ms. Running script /opt/grails-1.2.0/scripts/ListPlugins_.groovy Environment set to development Reading remote plugin list ... Plug-ins available in the core repository are listed below: hibernate <1.3.0.RC2 -- Hibernate for Grails tomcat <1.3.0.RC2 -- Apache Tomcat plugin for Grails webflow <1.3.0.RC2 -- Spring Web Flow Plugin Reading remote plugin list ... Plug-ins available in the default repository are listed below: spock <0.4-groovy-1.7-SNAPSHOT -- Spock Integration - spockframework.org Plug-ins you currently have installed are listed below: cloud-foundry 0.2 -- Cloud Foundry Plugin for Grails hibernate 1.2.0 -- Hibernate for Grails tomcat 1.2.0 -- Apache Tomcat plugin for Grails I find it very strange that it only finds the spock plugin. It makes me thing that either a)it is going to the wrong repository or b)my version setting is incorrect. Any ideas? Thanks, Padraic

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  • A business Case for Enterprise Python

    - by Srirangan
    Hi all, This will not be a "programming" question but more technology / platform related question. I'm trying to figure out whether Python can be a suitable Java alternative for enterprise / web applications. Which are the ideal cases where you would prefer to use Python instead of Java? How would a typical Python web application (databases/sessions/concurrency) perform as compared to a typical Java application? How do specific Python frameworks square up against Java based frameworks (Spring, SEAM, Grails etc.)? For businesses, switching from the Java infrastructure to a Python infrastructure .. is it too hard/expensive/resource intensive/not viable? Also shed some light on the business case for providing a Python + Google AppEngine based solution to the end customer. Will it be cost effective in an typical scenario? Sorry if I am asking too wide a question, I would have liked to keep it specific, but I need your help to evaluate Python as a whole from the perspectives of the programmers, service providing company and end business customer. For an SME, a Python/GoogleAppEngine based technology stack is a clear scalable and affordable platform. But what about a large MNC that already has a lot invested in Java. Thank you so much. I am researching this myself and will gladly share my conclusions here! Thank you, Srirangan

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  • Defining Light Coordinates

    - by Zachary
    I took a Computer Graphics exam a couple of days ago which had extra credit question like the following: A light can be defined in one of two ways. It can be defined in world coordinates, e.g. a street light, or in the viewer (eye coordinates), e.g., a head-lamp worn by a miner. In either case the viewpoint can freely change. Describe how the light should be transformed different in these two cases. Since I won't get to see the results of this until after spring break, I thought I would ask here. It seems like the analogies being used are misleading - could you not define a light source that is located at the viewers eye in world coordinates just as well as you could in eye coordinates? I've been doing some research on how OpenGL handles light, and it seems as though it always uses eye coordinates - the ModelView matrix would be applied to any light in world coordinates. In that case the answer may just be that you would have to transform light defined in world coordinates into eye coordinates using something like the ModelView matrix, while light defined in eye coordinates would only need to be transformed by the projection matrix. Then again I could be totally under thinking (or over thinking this). Another thought I had is that it determines which way you render shadows, but that has more to do with the location of the light and its type (point, directional, emission, etc) than what coordinates it is represented in. Any ideas?

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  • Glassfish: Defining Custom JNDI Names for Session Beans

    - by Adeel Ansari
    Background: Want to use GF3 in development, where as actual SIT, UAT, and production is using WAS. Problem: With the remote session beans everything is good to go, as GF3 gives a non-standard JNDI name, which is same as what WAS suggests, i.e. an absolute class name. Now for the local session beans WAS use the same absolute class name but with the prefix, i.e. ejblocal:. Whereas GF3 doesn't give any non-standard JNDI name for local session beans. GF3 came up with only portable name, java:global/..I need to find a way so I can use the same names for both. I am using EJB 3.0, WAS 7.9, and Glassfish 3. Don't have any xml confiuration for ejbs. Using Spring to inject the bean in Struts2 actions. With remote interfaces both servers are okay and agreed on a single convention, but for locals they differ. Is there any solution for this? Or just sun-ejb-jar.xml will solve it? Thanks.

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  • session regeneration in tomcat ?

    - by shrini1000
    Hi, I am using Spring security to secure my Java web application which is deployed in tomcat. I found out that it is vulnerable to session fixation attacks because tomcat does not create a new session upon successful log in. On debugging some more, here's what I found. For the following code (which is supposed to create a new session - pl. note, it's just a snippet and not full code): HttpSession session = request.getSession(false); session.invalidate(); session = request.getSession(true); // we now have a new session I thought a new session will be created, but tomcat simply uses the same session that got invalidated and hence the session id does not change. I searched online and found a solution which uses a 'valve' - http://marvinsmutterings.blogspot.com/2010/02/fixing-session-fixation-in-liferay-on.html but could not get it to work because it's looking for a jboss logging class and when I add it to lib, I get a reflection exception and the server doesn't start up. I'm using tomcat 5.5.28. Will be glad to have any pointers. Pl. let me know if you need more details, since I don't want to make this post too long. Sincere thanks!

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