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  • Video capture Performance

    - by volting
    I have noticed high CPU utilization in a number of applications (except mplayer) which read from the embedded webcam on my laptop. Bizarrely CPU utilization varies proportionately to the level of illumination present. I know that that high CPU usage has nothing to do with rendering the video, as I have written a simple app using the OpenCV library to simply grab frames from the webcam, and cpu usage is still high. I think that mplayer might be using my GPU (and the other apps aren't), but since its not an issue with rendering, I dont think this explains anything. Cheese Low light --- ~12% CPU Bright Light ---- ~63% CPU Camorama Low light --- ~7% CPU Bright Light ---- ~30% CPU Opencv C++ library, (display in a single highgui window) Low light --- ~13% CPU Bright Light ---- ~40% CPU (same test on windows 7, 4-9%) Mplayer No problem, 1-2% regardless of light levels Note: If all I want't to do is capture a feed from my webcam I would use mplayer and forget about it, but I'm developing an application which uses the OpenCV to capture a video feed among other things, performance is important.

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  • Using Sql Server Change Data Capture with a frequently changing schema

    - by Pete
    We are looking into enabling Sql Server Change Data Capture for a new subsystem we are building. It's not really because we need it, but we are being pushed for having a complete history traceability, and CDC would nicely solve this requirement with minimum effort on our parts. We are following an agile development process, which in this case means that we frequently make changes to the database schema, e.g. adding new columns, moving data to other columns, etc. We did a small test where we created a table, enabled CDC for that table, and then added a new column to the table. Changes to the new column is not registered in the CDC table. Is there a mechanism to update the CDC table to the new schema, and are there any best practices to how you deal with captured data when migrating the database schema?

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  • More Collateral to drive Remarketer Activity

    - by martin.morganti(at)oracle.com
    Over the last few months we have added a range of marketing materials to the Remarketer Level pages including an extensive set of Marketing Kits to support the Solution Kits previously available. As part of the continuing program, we have just added some additional training for Remarketers at no cost. In addition to the Oracle 1-Click Technology Products Guided Learning Path which explains about the program and how to position the products, we have added Oracle Database 11g 1-Click Technology Sales Guided Learning Path. This Learning path allows Remarketers to get access to more detailed training on the Oracle 11G database and so develop their understanding of the opportunities they could be benefiting from today, by reselling the 1-click products. This is in direct response to requests to make more training available to the Remarketers, so take the opportunity to let your Remarketer customers and prospects know about this additional training and how they can Jump Start a resell business with Oracle today with No Fees, No Barriers and No Excuses.

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  • Conflict between Change Control and ASL Mapping

    - by Jie Chen
    Yesterday I got one strange report that on Agile 9.3.1.2, adding a Supplier into Item's Supplier tab will always remove all the data from Item.PageTwo.MultiList01 field which is assigned to a User Group list. The detailed problem description is like below. In JavaClient, MultiList01 attribute on Parts class's PageTwo tab is enabled and assigned with User Group list. On WebClient, user created a new Part and assign MultiList01 with two UserGroups: "Global User Group Test1" and "Personal Group_Test1". Then go to Suppliers tab to add three Suppliers. Switch back to Part's TitleBlock, will see MultiList01 loses the User Group data. To confirm if MultiList01 really loses the data or it saves with other wrong data, I need to check the database and find strange data that MultiList01 saves wrong data ",7976911,7976907,7976959,", which are exactly the ID of these three Suppliers. Then I can suspect the Supplier attribute on Suppliers tab must be mapped to MultiList01. However when I check Supplier in JavaClient, the "ASL mapped to" is blank. More interesting thing is the database clearly shows Supplier attribute (Base ID =2000004219) is mapped to 2090, which is PageTwo.MultiList01 Base ID. Till now, we can get a conclusion that Supplier data is really mapped to MultiList01, though we assign MultiList01 to User Group list and Supplier does not set "ASL mapped to". It must be another function which overrides "ASL mapped to" visibility in JavaClient with high priority. That is the "Change Controlled" function. We immediately see "ASL mapped to" with value "MultiList01" when we disable Change Controlled for Multilist01 If one attribute is Change Controlled, Supplier data cannot be mapped to this attribute theoretically because Supplier could be dynamically modified by users, not by Changes. In real situation of Agile 9.3.1.2, it could be a Code Defect. We can imagine the scenario customer met. He setup Parts.PageTwo.Multilist01 assigned with Supplier list, then in Parts.Suppliers.Supplier attribute, he set "ASL mapped to" to "Multilist01". Later company business is changed, so he set Multilist01 with Change Controlled and re-assign with User Group list. He forgot to remove "ASL mapped to" before he did modifications to Multilist01. Finally we know the solution, it depends on real business. If still need to mapping Supplier to Parts.PageTwo attribute, should modify "ASL mapped to" to other one attribute which already has assigned with Suppliers list. If do not need "ASL mapped to" function, should delete the data from database level. We cannot do it from JavaClient UI. delete propertytable where id in (select p.id from propertytable p, nodetable n where p.parentid =n.id and n.inherit=2000004219 and propertyid=794)

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  • SQLite with two python processes accessing it: one reading, one writing

    - by BBnyc
    I'm developing a small system with two components: one polls data from an internet resource and translates it into sql data to persist it locally; the second one reads that sql data from the local instance and serves it via json and a restful api. I was originally planning to persist the data with postgresql, but because the application will have a very low-volume of data to store and traffic to serve, I thought that was overkill. Is SQLite up to the job? I love the idea of the small footprint and no need to maintain yet another sql server for this one task, but am concerned about concurrency. It seems that with write ahead logging enabled, concurrently reading and writing a SQLite database can happen without locking either process out of the database. Can a single SQLite instance sustain two concurrent processes accessing it, if only one reads and the other writes? I started writing the code but was wondering if this is a misapplication of SQLite.

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  • Java Spotlight Episode 100: JavaOne 2012 Part 1

    - by Roger Brinkley
    An interview with Arun Gupta on Glassfish, Geertjan Wielenga on Netbeans, and 15 year JavaOne alumin Robert Treacy on events and happenings at JavaOne 2012. Right-click or Control-click to download this MP3 file. You can also subscribe to the Java Spotlight Podcast Feed to get the latest podcast automatically. If you use iTunes you can open iTunes and subscribe with this link:  Java Spotlight Podcast in iTunes. Show Notes Events Sep 30-Oct 4, JavaONE, San Francisco Oct 3-4, Java Embedded @ JavaONE, San Francisco Oct 15-17, JAX London Oct 30-Nov 1, Arm TechCon, Santa Clara Oct 22-23, Freescale Technology Forum - Japan, Tokyo Oct 31, JFall, Netherlands Nov 2-3, JMagreb, Morocco Nov 13-17, Devoxx, Belgium Feature InterviewGlassFish Community Event will be conducted on Sep 30, 11am - 1pm. This is a fantastic opportunity for GlassFish users to meet and engage with the GlassFish Team in a casual setting.http://glassfish-event12.eventbrite.com/ Netbeans eventshttp://netbeans.dzone.com/news/meet-experts-java-ee-javafx http://netbeans.org/community/articles/javaone/2012/netbeans-day-2012.html http://netbeans.org/community/articles/javaone/2012/index.html

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  • No Cost 1-Click Remarketer Level Training

    - by martin.morganti(at)oracle.com
    The Remarketer level has proven to be a great success as a way of enabling Remarketers to Jump start a resale business with Oracle. As part of the Knowledge Zone for the 1-Click Products we have some no cost training available - the Oracle 1-Click Technology Products Guided Learning Path - which explains about the program and how to position Oracle products. We have been working to increase the training that is available for Remarketers and I am pleased to let you know that we have recently added more no cost training. The training path that we have released is the Oracle Database 11g 1-Click Technology Sales Guided Learning Path . This set of courses provides more detail on the Oracle 11G Database and will help you to better uncover and exploit opportunities for you to sell Oracle 11G as part of your solutions. So if you are interested in a No Fees, No Barriers No Excuses way to resell Oracle 1-Click products look at the Remarketer page and take the free 1-Click Guided Learning paths in the Training Section to kick start your activity.

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  • Why are people using C instead of C++? [closed]

    - by Darth
    Possible Duplicate: When to use C over C++, and C++ over C? Many times I've stumbled upon people saying that C++ is not always better than C. Great example here would be the Linux kernel, where they simply decided to use C instead of C++ because it had better compilers at the time. But that's many years ago and a lot has changed. So the question is, why are people still using C over C++? I gues there are probably some cases (like embedded devices), where there simply isn't a good C++ compiler, or am I wrong here? What are the other cases when it is better to go with C instead of C++?

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  • Is it possible to use Google Analytics to track file downloads?

    - by Eric Falsken
    It's always bothered me that Google Analytics (and similar embedded web traffic monitoring services) can only see a reflection of the traffic going to my server and can only see page visits since it depends on the browser executing a Javascript snippet. If I want to track real downloads of a software package (ZIP file), there's no way Google Analytics can possibly tell me that because its javascript can't be attached to a ZIP file. Is there a way I can upload my log files to Google so that the pointy-haired boss can see downloads of our ZIP/PDF/BIN files and not just visits to the download page?

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  • Select,Insert,Update and Delete data with LINQ to SQL in an ASP.Net application

    - by nikolaosk
    As you might have guessed I am continuing my LINQ to SQL posts. I am teaching a course right now on ADO.Net 3.5 (LINQ & EF) and I know a lot of people who have learned through my blog and my style of writing. I am going to use a step by step example to demonstrate how to select,update,insert,delete data through LINQ to SQL into the database. If you want to have a look on how to return data from a database with LINQ to SQL and stored procedures click here . If you want to have a look on how to...(read more)

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  • How does affliate marketing work, technically?

    - by Ron Gonzales
    There are lots of companies like Commision Junction that let you sell other people's products for a commission. How do these programs work, technically? Ie, are you simply given a link to the product you want to sell with an embedded ID in the URL? Does it involve cookies somehow? Do you take the order yourself and forward the information to the actual supplier of the goods/services? And how do you know if the program or the 'affliate network' isn't ripping you off by not creditting you for a sale?

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  • Ever wonder why Earth spins?

    - by Gopinath
    Have you ever wonder why Earth spins on its axis and completes a revolution every day? Is there any force that keeps Earth spinning? Is that because of  Gravity or any Magnetic force? Check out this video to learn why Earth spins and the basics of physics behind the magic If you find that above video is in simple English and it’s not convincing physicist inside you, lets hear from a NASA scientist in the embedded video. A NASA scientist explains how Earth rotation has started, how fast it was billions of years ago and what caused it to slow down to 24 hours to complete a revolution   Thanks @pinaldev

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  • Suggestions needed on an architecture for a multiple clients and customisable web application

    - by ValidfroM
    Our product is a web based course managemant system. We have 10+ clients and in future we may get more clients. (Asp.net,SQL Server) Currently if one of our customers need extra functionality or customised business logic, we will change the db schema and code to meet the needs. (we only have one branch code base and one database schema) To make the change wont affect each others route, we use a client flag, which defined in a web config file, thus those extra fields and biz logic only applied to a particular customer's system. if(ClientId = 'ABC') { //DO ABC Stuff } else { //Normal Route } One of our senior colleagues said, in this way, small company like us can save resources on supporting multiple resources. But what I feel is, this strategy makes our code and database even harder to maintain. Anyone there crossed similar situation? How do you handle that?

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  • JDeveloper and Upgrading Your JDK on Ubuntu

    - by Duncan Mills
    One little gotcha, if you, as I did recently, upgrade your JDK on Ubuntu then you may have to make sure you reflect that change in a couple of places for JDeveloper to stay happy. Assuming that you've installed from the jar version of the JDeveloper installer, then the JDK that you specified at install time will be recorded in the .jdev_jdk file in your home directory.However, be aware that this is not the only reference to the absolute path of the JDK. When you run the embedded WebLogic for the first time then the .jdeveloper/system11.1.1.3.37.56.60/DefaultDomain/bin/startWebLogic.shscript will be created, and associated with that, the setDomainEnv.sh script in the same directory. So, if you do want to change the JDK location be sure to change this file as well. (or of course do everything with symbolic links)

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  • Unexpected advantage of Engineered Systems

    - by user12244672
    It's not surprising that Engineered Systems accelerate the debugging and resolution of customer issues. But what has surprised me is just how much faster issue resolution is with Engineered Systems such as SPARC SuperCluster. These are powerful, complex, systems used by customers wanting extreme database performance, app performance, and cost saving server consolidation. A SPARC SuperCluster consists or 2 or 4 powerful T4-4 compute nodes, 3 or 6 extreme performance Exadata Storage Cells, a ZFS Storage Appliance 7320 for general purpose storage, and ultra fast Infiniband switches.  Each with its own firmware. It runs Solaris 11, Solaris 10, 11gR2, LDoms virtualization, and Zones virtualization on the T4-4 compute nodes, a modified version of Solaris 11 in the ZFS Storage Appliance, a modified and highly tuned version of Oracle Linux running Exadata software on the Storage Cells, another Linux derivative in the Infiniband switches, etc. It has an Infiniband data network between the components, a 10Gb data network to the outside world, and a 1Gb management network. And customers can run whatever middleware and apps they want on it, clustered in whatever way they want. In one word, powerful.  In another, complex. The system is highly Engineered.  But it's designed to run general purpose applications. That is, the physical components, configuration, cabling, virtualization technologies, switches, firmware, Operating System versions, network protocols, tunables, etc. are all preset for optimum performance and robustness. That improves the customer experience as what the customer runs leverages our technical know-how and best practices and is what we've tested intensely within Oracle. It should also make debugging easier by fixing a large number of variables which would otherwise be in play if a customer or Systems Integrator had assembled such a complex system themselves from the constituent components.  For example, there's myriad network protocols which could be used with Infiniband.  Myriad ways the components could be interconnected, myriad tunable settings, etc. But what has really surprised me - and I've been working in this area for 15 years now - is just how much easier and faster Engineered Systems have made debugging and issue resolution. All those error opportunities for sub-optimal cabling, unusual network protocols, sub-optimal deployment of virtualization technologies, issues with 3rd party storage, issues with 3rd party multi-pathing products, etc., are simply taken out of the equation. All those error opportunities for making an issue unique to a particular set-up, the "why aren't we seeing this on any other system ?" type questions, the doubts, just go away when we or a customer discover an issue on an Engineered System. It enables a really honed response, getting to the root cause much, much faster than would otherwise be the case. Here's a couple of examples from the last month, one found in-house by my team, one found by a customer: Example 1: We found a node eviction issue running 11gR2 with Solaris 11 SRU 12 under extreme load on what we call our ExaLego test system (mimics an Exadata / SuperCluster 11gR2 Exadata Storage Cell set-up).  We quickly established that an enhancement in SRU12 enabled an 11gR2 process to query Infiniband's Subnet Manager, replacing a fallback mechanism it had used previously.  Under abnormally heavy load, the query could return results which were misinterpreted resulting in node eviction.  In several daily joint debugging sessions between the Solaris, Infiniband, and 11gR2 teams, the issue was fully root caused, evaluated, and a fix agreed upon.  That fix went back into all Solaris releases the following Monday.  From initial issue discovery to the fix being put back into all Solaris releases was just 10 days. Example 2: A customer reported sporadic performance degradation.  The reasons were unclear and the information sparse.  The SPARC SuperCluster Engineered Systems support teams which comprises both SPARC/Solaris and Database/Exadata experts worked to root cause the issue.  A number of contributing factors were discovered, including tunable parameters.  An intense collaborative investigation between the engineering teams identified the root cause to a CPU bound networking thread which was being starved of CPU cycles under extreme load.  Workarounds were identified.  Modifications have been put back into 11gR2 to alleviate the issue and a development project already underway within Solaris has been sped up to provide the final resolution on the Solaris side.  The fixed SPARC SuperCluster configuration greatly aided issue reproduction and dramatically sped up root cause analysis, allowing the correct workarounds and fixes to be identified, prioritized, and implemented.  The customer is now extremely happy with performance and robustness.  Since the configuration is common to other customers, the lessons learned are being proactively rolled out to other customers and incorporated into the installation procedures for future customers.  This effectively acts as a turbo-boost to performance and reliability for all SPARC SuperCluster customers.  If this had occurred in a "home grown" system of this complexity, I expect it would have taken at least 6 months to get to the bottom of the issue.  But because it was an Engineered System, known, understood, and qualified by both the Solaris and Database teams, we were able to collaborate closely to identify cause and effect and expedite a solution for the customer.  That is a key advantage of Engineered Systems which should not be underestimated.  Indeed, the initial issue mitigation on the Database side followed by final fix on the Solaris side, highlights the high degree of collaboration and excellent teamwork between the Oracle engineering teams.  It's a compelling advantage of the integrated Oracle Red Stack in general and Engineered Systems in particular.

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  • Spectacular Explosion On Sun [Video]

    - by Gopinath
    Yesterday seems to be it’s too hot inside the crust of Sun and it resulted in an big explosion!! An explosion that was spectacular to watch and the event was something like never seen before : a solar flare, a coronal wave, a filament eruption, a coronal mass ejection, coronal rain and a coronal mass ejection to name a few. Check the embedded video Did you notice the hole on the Sun when it exploded? It’s a really very big one and can accommodate many Earth’s into that (check this for size comparison) Image and story via Geeked On Goddard This article titled,Spectacular Explosion On Sun [Video], was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • php+mysql account management software?

    - by kdavis8
    I need an account system added to my website as a plugin to all of my HTML pages. The account system plugin needs to,register new users, log in current users, remove users who want to disconnect service, and manipulate all of these things via database on my web server. However, I do not know how to program in the PHP language or create and manipulate MySQL databases. I want a program that can create and manipulate the MySQL database automatically for my website and handle also PHP calls automatically. Are there any open source freeware programs out there that i can use? If so what are the names of these freeware?

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  • Strategies for Indexing Custom Fields in RavenDB

    - by Adrian Thompson Phillips
    In the relational database world, if I was developing a CRM system and wanted to have the user add their own custom fields that are searchable, I could have tables that store the name of the new column, the data type and the value, etc. (which would be less inefficient to index) or I could use the less elegant (but more searchable) solution that software like Dynamics and SharePoint use, whereas I create a load of columns on my aggregate root called CustomInt1, CustomInt2, etc. (which looks dirty and has a limit of how many custom fields a user can have, but has indexing advantages). But my questions is this, in NoSQL databases, what would be the best way of achieving the same thing? My priority would be for searchability. So what would be the best way to store this data? If I used a predefined set of properties (i.e. CustomData1, CustomData2, etc.), because these are all stored as JSON (i.e. strings) in the database, does this make it simpler because I don't have to worry about data types?

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  • XmlWriter and lower ASCII characters

    - by Rick Strahl
    Ran into an interesting problem today on my CodePaste.net site: The main RSS and ATOM feeds on the site were broken because one code snippet on the site contained a lower ASCII character (CHR(3)). I don't think this was done on purpose but it was enough to make the feeds fail. After quite a bit of debugging and throwing in a custom error handler into my actual feed generation code that just spit out the raw error instead of running it through the ASP.NET MVC and my own error pipeline I found the actual error. The lovely base exception and error trace I got looked like this: Error: '', hexadecimal value 0x03, is an invalid character. at System.Xml.XmlUtf8RawTextWriter.InvalidXmlChar(Int32 ch, Byte* pDst, Boolean entitize)at System.Xml.XmlUtf8RawTextWriter.WriteElementTextBlock(Char* pSrc, Char* pSrcEnd)at System.Xml.XmlUtf8RawTextWriter.WriteString(String text)at System.Xml.XmlWellFormedWriter.WriteString(String text)at System.Xml.XmlWriter.WriteElementString(String localName, String ns, String value)at System.ServiceModel.Syndication.Rss20FeedFormatter.WriteItemContents(XmlWriter writer, SyndicationItem item, Uri feedBaseUri)at System.ServiceModel.Syndication.Rss20FeedFormatter.WriteItem(XmlWriter writer, SyndicationItem item, Uri feedBaseUri)at System.ServiceModel.Syndication.Rss20FeedFormatter.WriteItems(XmlWriter writer, IEnumerable`1 items, Uri feedBaseUri)at System.ServiceModel.Syndication.Rss20FeedFormatter.WriteFeed(XmlWriter writer)at System.ServiceModel.Syndication.Rss20FeedFormatter.WriteTo(XmlWriter writer)at CodePasteMvc.Controllers.ApiControllerBase.GetFeed(Object instance) in C:\Projects2010\CodePaste\CodePasteMvc\Controllers\ApiControllerBase.cs:line 131 XML doesn't like extended ASCII Characters It turns out the issue is that XML in general does not deal well with lower ASCII characters. According to the XML spec it looks like any characters below 0x09 are invalid. If you generate an XML document in .NET with an embedded &#x3; entity (as mine did to create the error above), you tend to get an XML document error when displaying it in a viewer. For example, here's what the result of my  feed output looks like with the invalid character embedded inside of Chrome which displays RSS feeds as raw XML by default: Other browsers show similar error messages. The nice thing about Chrome is that you can actually view source and jump down to see the line that causes the error which allowed me to track down the actual message that failed. If you create an XML document that contains a 0x03 character the XML writer fails outright with the error: '', hexadecimal value 0x03, is an invalid character. The good news is that this behavior is overridable so XML output can at least be created by using the XmlSettings object when configuring the XmlWriter instance. In my RSS configuration code this looks something like this:MemoryStream ms = new MemoryStream(); var settings = new XmlWriterSettings() { CheckCharacters = false }; XmlWriter writer = XmlWriter.Create(ms,settings); and voila the feed now generates. Now generally this is probably NOT a good idea, because as mentioned above these characters are illegal and if you view a raw XML document you'll get validation errors. Luckily though most RSS feed readers however don't care and happily accept and display the feed correctly, which is good because it got me over an embarrassing hump until I figured out a better solution. How to handle extended Characters? I was glad to get the feed fixed for the time being, but now I was still stuck with an interesting dilemma. CodePaste.net accepts user input for code snippets and those code snippets can contain just about anything. This means that ASP.NET's standard request filtering cannot be applied to this content. The code content displayed is encoded before display so for the HTML end the CHR(3) input is not really an issue. While invisible characters are hardly useful in user input it's not uncommon that odd characters show up in code snippets. You know the old fat fingering that happens when you're in the middle of a coding session and those invisible characters do end up sometimes in code editors and then end up pasted into the HTML textbox for pasting as a Codepaste.net snippet. The question is how to filter this text? Looking back at the XML Charset Spec it looks like all characters below 0x20 (space) except for 0x09 (tab), 0x0A (LF), 0x0D (CR) are illegal. So applying the following filter with a RegEx should work to remove invalid characters:string code = Regex.Replace(item.Code, @"[\u0000-\u0008,\u000B,\u000C,\u000E-\u001F]", ""); Applying this RegEx to the code snippet (and title) eliminates the problems and the feed renders cleanly.© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  XML   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • NetBeans, JSF, and MySQL Primary Keys using AUTO_INCREMENT

    - by MarkH
    I recently had the opportunity to spin up a small web application using JSF and MySQL. Having developed JSF apps with Oracle Database back-ends before and possessing some small familiarity with MySQL (sans JSF), I thought this would be a cakewalk. Things did go pretty smoothly...but there was one little "gotcha" that took more time than the few seconds it really warranted. The Problem Every DBMS has its own way of automatically generating primary keys, and each has its pros and cons. For the Oracle Database, you use a sequence and point your Java classes to it using annotations that look something like this: @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="POC_ID_SEQ") @SequenceGenerator(name="POC_ID_SEQ", sequenceName="POC_ID_SEQ", allocationSize=1) Between creating the actual sequence in the database and making sure you have your annotations right (watch those typos!), it seems a bit cumbersome. But it typically "just works", without fuss. Enter MySQL. Designating an integer-based field as PRIMARY KEY and using the keyword AUTO_INCREMENT makes the same task seem much simpler. And it is, mostly. But while NetBeans cranks out a superb "first cut" for a basic JSF CRUD app, there are a couple of small things you'll need to bring to the mix in order to be able to actually (C)reate records. The (RUD) performs fine out of the gate. The Solution Omitting all design considerations and activity (!), here is the basic sequence of events I followed to create, then resolve, the JSF/MySQL "Primary Key Perfect Storm": Fire up NetBeans. Create JSF project. Create Entity Classes from Database. Create JSF Pages from Entity Classes. Test run. Try to create record and hit error. It's a simple fix, but one that was fun to find in its completeness. :-) Even though you've told it what to do for a primary key, a MySQL table requires a gentle nudge to actually generate that new key value. Two things are needed to make the magic happen. First, you need to ensure the following annotation is in place in your Java entity classes: @GeneratedValue(strategy = GenerationType.IDENTITY) All well and good, but the real key is this: in your controller class(es), you'll have a create() function that looks something like this, minus the comment line and the setId() call in bold red type:     public String create() {         try {             // Assign 0 to ID for MySQL to properly auto_increment the primary key.             current.setId(0);             getFacade().create(current);             JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("CategoryCreated"));             return prepareCreate();         } catch (Exception e) {             JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));             return null;         }     } Setting the current object's primary key attribute to zero (0) prior to saving it tells MySQL to get the next available value and assign it to that record's key field. Short and simple…but not inherently obvious if you've never used that particular combination of NetBeans/JSF/MySQL before. Hope this helps! All the best, Mark

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  • How can I optimise ext4 for reliability?

    - by amin
    As ext4 was introduced as more reliable than ext3 with block journals, is there any chance to suppose it 100% reliable? What if enabling block journaling on it, which is disabled by default? As friend's guide to explain my case in more detail: I have an embedded linux device, after installation keyboard and monitor is detached and it works standalone. My duty is to make sure it has reliable file-system so with errors there is no way for manual correct faults on device. I can't force my customer to use a ups with each device to ensure no fault by power-failure. What more can ext4 offer me besides block journaling? Thanks in advance.

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