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• Updating an ADF Web Service Data Control When Service Structure or Location Change

  - by Shay Shmeltzer

  The web service data control in Oracle ADF gives you a simplified approach to consuming services in ADF applications, and now with ADF Mobile the usage of this service seems to be growing. A frequent question we get is what happens if the service that I'm consuming changes - how do I update my data control? Well, first we should mention that if you do a good design of your application before you actually code - then things like Web service method signature shouldn't change. The signature is the contract between the publisher and the consumer, and contracts shouldn't be broken. But in reality things do change during development stages, so here is how you can update both method signatures and service location with the Web service data control: After watching this video you might be tempted to not copy the WSDLs to your project - which lets you use the right click update on a data control. However there is a reason why the copy is on by default, it reduces network traffic when you are actually running your application since ADF doesn't need to go to the server to find out the service structure. So for runtime performance, you probably should keep the WSDL local.  I encourage you to further look into both the connections.xml file where your service location is saved, and the datacontrols.dcx file where its definition is kept to get an even deeper understanding of how ADF works underneath the declarative layers.

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• Flashback Data Archives: Ein gutes Gedächtnis für DBA und Entwickler

  - by Heinz-Wilhelm Fabry (DBA Community)

  Daten werden gespeichert und zum Teil lange aufbewahrt. Mitunter werden Daten nach ihrer ersten Speicherung geändert, vielleicht sogar mehrfach. Je nach gesetzlicher oder betrieblicher Vorgabe müssen die Veränderungen sogar nachverfolgbar sein. Damit sind zugleich Mechanismen gefordert, die sicherstellen, dass die Folge der Versionen lückenlos ist. Und implizit bedeutet das zusätzlich, dass die Versionen auch vor Löschen und Verändern geschützt sein müssen. Das Versionieren kann über die Anwendung, mit der die Daten auch erfasst werden, erfolgen, über Trigger oder über besondere Werkzeuge. Jede dieser Lösungen hat ihre eigenen Schwächen. Zusätzlich steht die Frage nach dem Schutz vor unerlaubtem Löschen oder Ändern versionierter Daten im Raum. Flashback Data Archives lösen diese Frage, denn sie bieten nicht nur einen wirksamen Mechanismus zum Versionieren von Datensätzen, sondern sie schützen diese Versionen auch vor Veränderung und löschen sie schließlich sogar automatisch nach Ablauf ihrer Aufbewahrungsfrist.Ursprünglich wurden die Archive als eigenständige Option zur Enterprise Edition der Oracle Database 11g unter dem Namen Total Recall eingeführt. Ende Juni 2012 verloren die Flashback Data Archives ihren Status als eigenständige Option. Weil die Archive aber grundsätzlich komprimiert wurden, hat Oracle sie stattdessen zu einem Feature der Advanced Compression Option der Enterprise Edition (ACO) gemacht. Seit der Version 11.2.0.4 der Datenbank ist das Komprimieren aber für die Archive nicht mehr zwangsläufig, sondern optional. Damit gibt es lizenzrechtlich erneut eine Änderung: Wer die Kompression verwendet, der muss nach wie vor ACO lizensieren. Wer die Flashback Data Archives dagegen ohne Kompression verwendet - also zum Beispiel Entwickler -, dem stehen sie ab 11.2.0.4 aufwärts im Lieferumfang aller Editionen der Datenbank zur Verfügung. Diese Änderung ist in den Handbüchern zur Lizensierung der Versionen 11.2 und 12.1 der Datenbank dokumentiert. Im Rahmen der DBA Community ist bereits über die Flashback Data Archives berichtet worden. Der hier vorliegende Artikel ersetzt alle vorangegangenen Beiträge zum Thema.

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• Data indexing frameworks fit for large E-Commerce applications

  - by Dabu

  we wrote and still maintain a large E-Commerce application. Our feature list resembles what you would expect from most shops. We'd like to improve some of our features, and now the search/suggestion list functionality (enter some letters, a JScripted suggestion list appears) has caught our eye. Currently, we use http://xapian.org/. It has some drawbacks. Firstly, it's not actually the right solution. It has been created to index documents, not ever-changing data in a granularity that an E-Commerce application would need. Secondly, the load on the database is significant when we reindex all data every night. We'd like a framework that has been designed for indexing database data, which can add to the index easily and without much load, which can supply data changes in the backoffice quickly to the frontend without much load and delay. I'm aware of the fact that Xapian is Open Source and even Free Software, so we could adapt it to our needs if we decided to invest the time and manpower. But taking a quick look around for a solution more suited seems fair, right? Oh, and commercial applications are fine, too. FOSS is not required. Thanks a bunch.

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• Generic Repositories with DI & Data Intensive Controllers

  - by James

  Usually, I consider a large number of parameters as an alarm bell that there may be a design problem somewhere. I am using a Generic Repository for an ASP.NET application and have a Controller with a growing number of parameters. public class GenericRepository<T> : IRepository<T> where T : class { protected DbContext Context { get; set; } protected DbSet<T> DbSet { get; set; } public GenericRepository(DbContext context) { Context = context; DbSet = context.Set<T>(); } ...//methods excluded to keep the question readable } I am using a DI container to pass in the DbContext to the generic repository. So far, this has met my needs and there are no other concrete implmentations of IRepository<T>. However, I had to create a dashboard which uses data from many Entities. There was also a form containing a couple of dropdown lists. Now using the generic repository this makes the parameter requirments grow quickly. The Controller will end up being something like public HomeController(IRepository<EntityOne> entityOneRepository, IRepository<EntityTwo> entityTwoRepository, IRepository<EntityThree> entityThreeRepository, IRepository<EntityFour> entityFourRepository, ILogError logError, ICurrentUser currentUser) { } It has about 6 IRepositories plus a few others to include the required data and the dropdown list options. In my mind this is too many parameters. From a performance point of view, there is only 1 DBContext per request and the DI container will serve the same DbContext to all of the Repositories. From a code standards/readability point of view it's ugly. Is there a better way to handle this situation? Its a real world project with real world time constraints so I will not dwell on it too long, but from a learning perspective it would be good to see how such situations are handled by others.

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• Compressing 2D level data

  - by Lucius

  So, I'm developing a 2D, tile based game and a map maker thingy - all in Java. The problem is that recently I've been having some memory issues when about 4 maps are loaded. Each one of these maps are composed of 128x128 tiles and have 4 layers (for details and stuff). I already spent a good amount of time searching for solutions and the best thing I found was run-length enconding (RLE). It seems easy enough to use with static data, but is there a way to use it with data that is constantly changing, without a big drop in performance? In my maps, supposing I'm compressing the columns, I would have 128 rows, each with some amount of data (hopefully less than it would be without RLE). Whenever I change a tile, that whole row would have to be checked and I'm affraid that would slow down too much the production (and I'm in a somewhat tight schedule). Well, worst case scenario I work on each map individually, and save them using RLE, but it would be really nice if I could avoind that. EDIT: What I'm currently using to store the data for the tiles is a 2D array of HashMaps that use the layer as key and store the id of the tile in that position - like this: private HashMap< Integer, Integer [][]

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• Non use of persisted data – Part deux

  - by Dave Ballantyne

  In my last blog I showed how persisted data may not be used if you have used the base data on an include on an index. That wasn't the only problem ive had that showed the same symptom.  Using the same code as before,  I was executing similar to the below : select BillToAddressID,SOD.SalesOrderDetailID,SOH.CleanedGuid from sales.salesorderheader SOH join Sales.SalesOrderDetail SOD on SOH.SalesOrderID = SOD.SalesOrderID But,  due to a distribution error in statistics i found it necessary to use a table hint.  In this case, I wanted to force a loop join select BillToAddressID,SOD.SalesOrderDetailID,SOH.CleanedGuid from sales.salesorderheader SOH inner loop join Sales.SalesOrderDetail SOD on SOH.SalesOrderID = SOD.SalesOrderID   But, being the diligent  TSQL developer that I am ,looking at the execution plan I noticed that the ‘compute scalar’ operator was again calling the function.  Again,  profiler is a more graphic way to view this…..   All very odd,  just because ive forced a join , that has NOTHING, to do with my persisted data then something is causing the data to be re-evaluated. Not sure if there is any easy fix you can do to the TSQL here, but again its a lesson learned (or rather reinforced) examine the execution plan of every query you write to ensure that it is operating as you thought it would.

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• Process Improvement and the Data Professional

  - by BuckWoody

  Don’t be afraid of that title – I’m not talking about Six Sigma or anything super-formal here. In many organizations, there are more folks in other IT roles than in the Data Professional area. In other words, there are more developers, system administrators and so on than there are the “DBA” role. That means we often have more to do than the time we need to do it. And, oddly enough, the first thing that is sacrificed is process improvement – the little things we need to do to make the day go faster in the first place. Then we get even more behind, the work piles up and…well, you know all about that. Earlier I challenged you to find 10-30 minutes a day to study. Some folks wrote back and asked “where do I start”? Well, why not be super-efficient and combine that time with learning how to make yourself more efficient? Try out a new scripting language, learn a new tool that automates things or find out ways others have automated their systems. In general, find out what you’re doing and how, and then see if that can be improved. It’s kind of like doing a performance tuning gig on yourself! If you’re pressed for time, look for bite-sized articles (like the ones I’ve done here for PowerShell and SQL Server) that you can follow in a “serial” fashion. In a short time you’ll have a new set of knowledge you can use to make your day faster. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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• Displaying a Grid of Data in ASP.NET MVC

  One of the most common tasks we face as a web developers is displaying data in a grid. In its simplest incarnation, a grid merely displays information about a set of records - the orders placed by a particular customer, perhaps; however, most grids offer features like sorting, paging, and filtering to present the data in a more useful and readable manner. In ASP.NET WebForms the GridView control offers a quick and easy way to display a set of records in a grid, and offers features like sorting, paging, editing, and deleting with just a little extra work. On page load, the GridView automatically renders as an HTML <table> element, freeing you from having to write any markup and letting you focus instead on retrieving and binding the data to display to the GridView. In an ASP.NET MVC application, however, developers are on the hook for generating the markup rendered by each view. This task can be a bit daunting for developers new to ASP.NET MVC, especially those who have a background in WebForms. This is the first in a series of articles that explore how to display grids in an ASP.NET MVC application. This installment starts with a walk through of creating the ASP.NET MVC application and data access code used throughout this series. Next, it shows how to display a set of records in a simple grid. Future installments examine how to create richer grids that include sorting, paging, filtering, and client-side enhancements. We'll also look at pre-built grid solutions, like the Grid component in the MvcContrib project and JavaScript-based grids like jqGrid. But first things first - let's create an ASP.NET MVC application and see how to display database records in a web page. Read on to learn more! Read More >

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• Generate a Word document from list data

  - by PeterBrunone

  This came up on a discussion list lately, so I threw together some code to meet the need.  In short, a colleague needed to take the results of an InfoPath form survey and give them to the user in Word format.  The form data was already in a list item, so it was a simple matter of using the SharePoint API to get the list item, formatting the data appropriately, and using response headers to make the client machine treat the response as MS Word content.  The following rudimentary code can be run in an ASPX (or an assembly) in the 12 hive.  When you link to the page, send the list name and item ID in the querystring and use them to grab the appropriate data. // Clear the current response headers and set them up to look like a word doc.HttpContext.Current.Response.Clear();HttpContext.Current.Response.Charset ="";HttpContext.Current.Response.ContentType ="application/msword";string strFileName = "ThatWordFileYouWanted"+ ".doc";HttpContext.Current.Response.AddHeader("Content-Disposition", "inline;filename=" + strFileName);// Using the current site, get the List by name and then the Item by ID (from the URL).string myListName = HttpContext.Current.Request.Querystring["listName"];int myID = Convert.ToInt32(HttpContext.Current.Request.Querystring["itemID"]);SPSite oSite = SPContext.Current.Site;SPWeb oWeb = oSite.OpenWeb();SPList oList = oWeb.Lists["MyListName"];SPListItem oListItem = oList.Items.GetItemById(myID);// Build a string with the data -- format it with HTML if you like. StringBuilder strHTMLContent = newStringBuilder();// *// Here's where you pull individual fields out of the list item.// *// Once everything is ready, spit it out to the client machine.HttpContext.Current.Response.Write(strHTMLContent);HttpContext.Current.Response.End();HttpContext.Current.Response.Flush();

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• PASS Summit Preconference and Sessions

  - by Davide Mauri

  I’m very pleased to announce that I’ll be delivering a Pre-Conference at PASS Summit 2012. I’ll speak about Business Intelligence again (as I did in 2010) but this time I’ll focus only on Data Warehouse, since it’s big topic even alone. I’ll discuss not only what is a Data Warehouse, how it can be modeled and built, but also how it’s development can be approached using and Agile approach, bringing the experience I gathered in this field. Building the Agile Data Warehouse with SQL Server 2012 http://www.sqlpass.org/summit/2012/Sessions/SessionDetails.aspx?sid=2821 I’m sure you’ll like it, especially if you’re starting to create a BI Solution and you’re wondering what is a Data Warehouse, if it is still useful nowadays that everyone talks about Self-Service BI and In-Memory databases, and what’s the correct path to follow in order to have a successful project up and running. Beside this Preconference, I’ll also deliver a regular session, this time related to database administration, monitoring and tuning: DMVs: Power in Your Hands http://www.sqlpass.org/summit/2012/Sessions/SessionDetails.aspx?sid=3204 Here we’ll dive into the most useful DMVs, so that you’ll see how that can help in everyday management in order to discover, understand and optimze you SQL Server installation, from the server itself to the single query. See you there!!!!!

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• Two Weeks To Go, Still Time to Register

  - by speakjava

  Yes, it's now only two weeks to the start of the 17th JavaOne conference! This will be my ninth JavaOne, I came fairly late to this event, attending for the first time in 2002.  Since then I've missed two conferences, 2006 for the birth of my son (a reasonable excuse I think) and 2010 for reasons we'll not go into here.  I have quite the collection of show devices, I've still got the WoWee robot, the HTC phone for JavaFX, the programmable pen and the Sharp Zaurus.  The only one I didn't keep was the homePod music player (I wonder why?) JavaOne is a special conference for many reasons, some of which I list here: A great opportunity to catch up on the latest changes in the Java world.  This is not just in terms of the platform, but as much about what people are doing with Java to build new and cool applications. A chance to meet people.  We have these things called BoFs, which stands for "Birds of a Feather", as in "Birds of a feather, flock together".  The idea being to have sessions where people who are interested in the same topic don't just get to listen to a presentation, but get to talk about it.  These sessions are great, but I find that JavaOne is as much about the people I meet in the corridors and the discussions I have there as it is about the sessions I get to attend. Think outside the box.  There are a lot of sessions at JavaOne covering the full gamut of Java technologies and applications.  Clearly going to sessions that relate to your area of interest is great, but attending some of the more esoteric sessions can often spark thoughts and stimulate the imagination to go off and do new and exciting things once you get back. Get the lowdown from the Java community.  Java is as much about community as anything else and there are plenty of events where you can get involved.  The GlassFish party is always popular and for Java Champions and JUG leaders there's a couple of special events too. Not just all hard work.  Oracle knows how to throw a party and the appreciation event will be a great opportunity to mingle with peers in a more relaxed environment.  This year Pearl Jam and Kings of Leon will be playing live.  Add free beer and what more could you want? So there you have it.  Just a few reasons for why you want to attend JavaOne this year.  Oh, and of course I'll be presenting three sessions which is even more reason to go.  As usual I've gone for some mainstream ("Custom Charts" for JavaFX) and some more 'out there' ("Java and the Raspberry Pi" and "Gestural Interfaces for JavaFX").  Once again I'll be providing plenty of demos so more than half my luggage this year will consist of a Kinect, robot arm, Raspberry Pis, gamepad and even an EEG sensor. If you're a student there's one even more attractive reason for going to JavaOne: It's Free! Registration is here.  Hope to see you there!

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• Keeping a domain model consistent with actual data

  - by fstuijt

  Recently domain driven design got my attention, and while thinking about how this approach could help us I came across the following problem. In DDD the common approach is to retrieve entities (or better, aggregate roots) from a repository which acts as a in-memory collection of these entities. After these entities have been retrieved, they can be updated or deleted by the user, however after retrieval they are essentially disconnected from the data source and one must actively inform the repository to update the data source and make is consistent again with our in-memory representation. What is the DDD approach to retrieving entities that should remain connected to the data source? For example, in our situation we retrieve a series of sensors that have a specific measurement during retrieval. Over time, these measurement values may change and our business logic in the domain model should respond to these changes properly. E.g., domain events may be raised if a sensor value exceeds a predefined threshold. However, using the repository approach, these sensor values are just snapshots, and are disconnected from the data source. Does any of you have an idea on how to solve this following the DDD approach?

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• PASS Summit Preconference and Sessions

  - by Davide Mauri

  I’m very pleased to announce that I’ll be delivering a Pre-Conference at PASS Summit 2012. I’ll speak about Business Intelligence again (as I did in 2010) but this time I’ll focus only on Data Warehouse, since it’s big topic even alone. I’ll discuss not only what is a Data Warehouse, how it can be modeled and built, but also how it’s development can be approached using and Agile approach, bringing the experience I gathered in this field. Building the Agile Data Warehouse with SQL Server 2012 http://www.sqlpass.org/summit/2012/Sessions/SessionDetails.aspx?sid=2821 I’m sure you’ll like it, especially if you’re starting to create a BI Solution and you’re wondering what is a Data Warehouse, if it is still useful nowadays that everyone talks about Self-Service BI and In-Memory databases, and what’s the correct path to follow in order to have a successful project up and running. Beside this Preconference, I’ll also deliver a regular session, this time related to database administration, monitoring and tuning: DMVs: Power in Your Hands http://www.sqlpass.org/summit/2012/Sessions/SessionDetails.aspx?sid=3204 Here we’ll dive into the most useful DMVs, so that you’ll see how that can help in everyday management in order to discover, understand and optimze you SQL Server installation, from the server itself to the single query. See you there!!!!!

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• is there an open source realtime collaborative wiki engine ?

  - by Jerome WAGNER

  Hello, I am looking for an - open source - real time - collaborative wiki engine. A sort of mix between mediawiki and an open source version of google docs where several users could see each other's edits in real time. Is there such a state-of-the-art beast ? Thanks Jerome Wagner

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• Daylight saving time and Timezone best practices

  - by Oded

  I am hoping to make this question and the answers to it the definitive guide to dealing with daylight saving time, in particular for dealing with the actual change overs. If you have anything to add, please do Many systems are dependent on keeping accurate time, the problem is with changes to time due to daylight savings - moving the clock forward or backwards. For instance, one has business rules in an order taking system that depend on the time of the order - if the clock changes, the rules might not be as clear. How should the time of the order be persisted? There is of course an endless number of scenarios - this one is simply an illustrative one. How have you dealt with the daylight saving issue? What assumptions are part of your solution? (looking for context here) As important, if not more so: What did you try that did not work? Why did it not work? I would be interested in programming, OS, data persistence and other pertinent aspects of the issue. General answers are great, but I would also like to see details especially if they are only available on one platform. Summary of answers and other data: (please add yours) Do: Always persist time according to a unified standard that is not affected by daylight savings. GMT and UTC have been mentioned by different people. Include the local time offset (including DST offset) in stored timestamps. Remember that DST offsets are not always an integer number of hours (e.g. Indian Standard Time is UTC+05:30). If using Java, use JodaTime. - http://joda-time.sourceforge.net/ Create a table TZOffsets with three columns: RegionClassId, StartDateTime, and OffsetMinutes (int, in minutes). See answer Check if your DBMS needs to be shutdown during transition. Business rules should always work on civil time. Internally, keep timestamps in something like civil-time-seconds-from-epoch. See answer Only convert to local times at the last possible moment. Don't: Do not use javascript date and time calculations in web apps unless you ABSOLUTELY have to. Testing: When testing make sure you test countries in the Western and Eastern hemispheres, with both DST in progress and not and a country that does not use DST (6 in total). Reference: Olson database, aka Tz_database - ftp://elsie.nci.nih.gov/pub Sources for Time Zone and DST - http://www.twinsun.com/tz/tz-link.htm ISO format (ISO 8601) - http://en.wikipedia.org/wiki/ISO_8601 Mapping between Olson database and Windows TimeZone Ids, from the Unicode Consortium - http://unicode.org/repos/cldr-tmp/trunk/diff/supplemental/windows_tzid.html TimeZone page on WikiPedia - http://en.wikipedia.org/wiki/Tz_database StackOverflow questions tagged dst - http://stackoverflow.com/questions/tagged/dst StackOverflow questions tagged timezone - http://stackoverflow.com/questions/tagged/timezone Other: Lobby your representative to end the abomination that is DST. We can always hope...

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• How can data not stored in a DB be accessed from any activity in Android?

  - by jul

  hi, I'm passing data to a ListView to display some restaurant names. Now when clicking on an item I'd like to start another activity to display more restaurant data. I'm not sure about how to do it. Shall I pass all the restaurant data in a bundle through the intent object? Or shall I just pass the restaurant id and get the data in the other activity? In that case, how can I access my restaurantList from the other activity? In any case, how can I get data from the restaurant I clicked on (the view only contains the name)? Any help, pointers welcome! Thanks Jul ListView lv= (ListView)findViewById(R.id.listview); lv.setAdapter( new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,restaurantList.getRestaurantNames())); lv.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View view, int position, long id) { Intent i = new Intent(Atable.this, RestaurantEdit.class); Bundle b = new Bundle(); //b.putInt("id", ? ); startActivityForResult(i, ACTIVITY_EDIT); } }); RestaurantList.java package org.digitalfarm.atable; import java.util.ArrayList; import java.util.List; public class RestaurantList { private List<Restaurant> restaurants = new ArrayList<Restaurant>(); public List<Restaurant> getRestaurants() { return this.restaurants; } public void setRestaurants(List<Restaurant> restaurants) { this.restaurants = restaurants; } public List<String> getRestaurantNames() { List<String> restaurantNames = new ArrayList<String>(); for (int i=0; i<this.restaurants.size(); i++) { restaurantNames.add(this.restaurants.get(i).getName()); } return restaurantNames; } } Restaurant.java package org.digitalfarm.atable; public class Restaurant { private int id; private String name; private float latitude; private float longitude; public int getId() { return this.id; } public void setId(int id) { this.id = id; } public String getName() { return this.name; } public void setName(String name) { this.name = name; } public float getLatitude() { return this.latitude; } public void setLatitude(float latitude) { this.latitude = latitude; } public float getLongitude() { return this.longitude; } public void setLongitude(float longitude) { this.longitude = longitude; } }

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• What are best practices for collecting, maintaining and ensuring accuracy of a huge data set?

  - by Kyle West

  I am posing this question looking for practical advice on how to design a system. Sites like amazon.com and pandora have and maintain huge data sets to run their core business. For example, amazon (and every other major e-commerce site) has millions of products for sale, images of those products, pricing, specifications, etc. etc. etc. Ignoring the data coming in from 3rd party sellers and the user generated content all that "stuff" had to come from somewhere and is maintained by someone. It's also incredibly detailed and accurate. How? How do they do it? Is there just an army of data-entry clerks or have they devised systems to handle the grunt work? My company is in a similar situation. We maintain a huge (10-of-millions of records) catalog of automotive parts and the cars they fit. We've been at it for a while now and have come up with a number of programs and processes to keep our catalog growing and accurate; however, it seems like to grow the catalog to x items we need to grow the team to y. I need to figure some ways to increase the efficiency of the data team and hopefully I can learn from the work of others. Any suggestions are appreciated, more though would be links to content I could spend some serious time reading. THANKS! Kyle

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• About Data Objects and DAO Design when using Hibernate

  - by X. Ma

  I'm hesitating between two designs of a database project using Hibernate. Design #1. (1) Create a general data provider interface, including a set of DAO interfaces and general data container classes. It hides the underneath implementation. A data provider implementation could access data in database, or an XML file, or a service, or something else. The user of a data provider does not to know about it. (2) Create a database library with Hibernate. This library implements the data provider interface in (1). The bad thing about Design #1 is that in order to hide the implementation details, I need to create two sets of data container classes. One in the general data provider interface - let's call them DPI-Objects, the other set is used in the database library, exclusively for entity/attribute mapping in Hibernate - let's call them H-Objects. In the DAO implementation, I need to read data from database to create H-Objects (via Hibernate) and then convert H-Objects into DPI-Objects. Design #2. Do not create a general data provider interface. Expose H-Objects directly to components that use the database lib. So the user of the database library needs to be aware of Hibernate. I like design #1 more, but I don't want to create two sets of data container classes. Is that the right way to hide H-Objects and other Hibernate implementation details from the user who uses the database-based data provider? Are there any drawbacks of Design #2? I will not implement other data provider in the new future, so should I just forget about the data provider interface and use Design #2? What do you think about this? Thanks for your time!

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• How do I bind an iTunes style source list to an NSTableView using Core Data?

  - by Austin

  I have an iTunes style interface in my application: Source list (NSOutlineView) on the left that contains different libraries and playlists with an NSTableView on the right side of the interface displaying information for "Presentations". Similar to iTunes, I am showing the same type of information in the table view whether a library or playlist is selected (title, author, date created, etc). I currently have an NSArrayController connected to my NSTableView and was setting the fetch predicate based on what was selected in the source list. This works fine when selecting a library because I can just set the fetch predicate to filter by the "type" field in my Presentation Core Data entity. When I try to adjust the fetch predicate for the playlist however, it doesn't look like there is any way to set the fetch predicate because I've got a table in between Playlists and Presentations to keep up with the order within the Playlist. According to the Apple docs, these type of predicates are not doable with Core Data (it basically doesn't multiple inner joins). Below is the relevant portion of my Data Model. Is my data model setup incorrectly? Should I drop the NSArrayController and handle connecting the NSTableView up by hand? I'm trying to figure out if there is a simple fix, or really a design flaw.

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• Handling missing/incomplete data in R--is there function to mask but not remove NAs?

  - by doug

  As you would expect from a DSL aimed at data analysis, R handles missing/incomplete data very well, for instance: Many R functions have an 'na.rm' flag that you can set to 'T' to remove the NAs: mean( c(5,6,12,87,9,NA,43,67), na.rm=T) But if you want to deal with NAs before the function call, you need to do something like this: to remove each 'NA' from a vector: vx = vx[!is.na(a)] to remove each 'NA' from a vector and replace it w/ a '0': ifelse(is.na(vx), 0, vx) to remove entire each row that contains 'NA' from a data frame: dfx = dfx[complete.cases(dfx),] All of these functions permanently remove 'NA' or rows with an 'NA' in them. Sometimes this isn't quite what you want though--making an 'NA'-excised copy of the data frame might be necessary for the next step in the workflow but in subsequent steps you often want those rows back (e.g., to calculate a column-wise statistic for a column that has missing rows caused by a prior call to 'complete cases' yet that column has no 'NA' values in it). to be as clear as possible about what i'm looking for: python/numpy has a class, 'masked array', with a 'mask' method, which lets you conceal--but not remove--NAs during a function call. Is there an analogous function in R?

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• How to write these two queries for a simple data warehouse, using ANSI SQL?

  - by morpheous

  I am writing a simple data warehouse that will allow me to query the table to observe periodic (say weekly) changes in data, as well as changes in the change of the data (e.g. week to week change in the weekly sale amount). For the purposes of simplicity, I will present very simplified (almost trivialized) versions of the tables I am using here. The sales data table is a view and has the following structure: CREATE TABLE sales_data ( sales_time date NOT NULL, sales_amt double NOT NULL ) For the purpose of this question. I have left out other fields you would expect to see - like product_id, sales_person_id etc, etc, as they have no direct relevance to this question. AFAICT, the only fields that will be used in the query are the sales_time and the sales_amt fields (unless I am mistaken). I also have a date dimension table with the following structure: CREATE TABLE date_dimension ( id integer NOT NULL, datestamp date NOT NULL, day_part integer NOT NULL, week_part integer NOT NULL, month_part integer NOT NULL, qtr_part integer NOT NULL, year_part integer NOT NULL, ); which partition dates into reporting ranges. I need to write queries that will allow me to do the following: Return the change in week on week sales_amt for a specified period. For example the change between sales today and sales N days ago - where N is a positive integer (N == 7 in this case). Return the change in change of sales_amt for a specified period. For in (1). we calculated the week on week change. Now we want to know how that change is differs from the (week on week) change calculated last week. I am stuck however at this point, as SQL is my weakest skill. I would be grateful if an SQL master can explain how I can write these queries in a DB agnostic way (i.e. using ANSI SQL).

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• [C#] How to receive uncrackable data or so ? ;P

  - by Prix

  Hi, I am working on an C# application to communicate with my website and retrieve some information from it, using SSL which is working just fine. Now what i want/need is a way to receive encrypted or codified or obfuscated data that if some one cracks my application they will not be able to decrypt the data because it needs something from the server (api, website) but yet the application needs to decrypt it in order to use it... initally i was thinking of an inside RSA pair or keys, to send and receive the encrypt data but let's consider that someone has cracked the application, they could just replace those keys for keys they have made, so i was looking into some methods but havent found or been able to think of any way to harder this... I was learning about RSA, encryption and such and started developing this as a self learning and got involved with it and now i am trying to figure out a way to receive data like that... I have considered obfuscating and compiling my code with packers and etc but this is not about packing it etc... i am more interested in knowing a better way to secure what i described i know it may or is impossible but yet i am looking forward to some approch. I would appreciate advices, suggestions and C# code samples, if you need more information or anything please let me know.

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• How do I authenticate an ADO.NET Data Service?

  - by lsb

  Hi! I've created an ADO.Net Data Service hosted in a Azure worker role. I want to pass credentials from a simple console client to the service then validate them using a QueryInterceptor. Unfortunately, the credentials don't seem to be making it over the wire. The following is a simplified version of the code I'm using, starting with the DataService on the server: using System; using System.Data.Services; using System.Linq.Expressions; using System.ServiceModel; using System.Web; namespace Oslo.Worker { [ServiceBehavior(AddressFilterMode = AddressFilterMode.Any)] public class AdminService : DataService<OsloEntities> { public static void InitializeService( IDataServiceConfiguration config) { config.SetEntitySetAccessRule("*", EntitySetRights.All); config.SetServiceOperationAccessRule("*", ServiceOperationRights.All); } [QueryInterceptor("Pairs")] public Expression<Func<Pair, bool>> OnQueryPairs() { // This doesn't work!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! if (HttpContext.Current.User.Identity.Name != "ADMIN") throw new Exception("Ooops!"); return p => true; } } } Here's the AdminService I'm using to instantiate the AdminService in my Azure worker role: using System; using System.Data.Services; namespace Oslo.Worker { public class AdminHost : DataServiceHost { public AdminHost(Uri baseAddress) : base(typeof(AdminService), new Uri[] { baseAddress }) { } } } And finally, here's the client code. using System; using System.Data.Services.Client; using System.Net; using Oslo.Shared; namespace Oslo.ClientTest { public class AdminContext : DataServiceContext { public AdminContext(Uri serviceRoot, string userName, string password) : base(serviceRoot) { Credentials = new NetworkCredential(userName, password); } public DataServiceQuery<Order> Orders { get { return base.CreateQuery<Pair>("Orders"); } } } } I should mention that the code works great with the signal exception that the credentials are not being passed over the wire. Any help in this regard would be greatly appreciated! Thanks....

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• faster way to compare rows in a data frame

  - by aguiar

  Consider the data frame below. I want to compare each row with rows below and then take the rows that are equal in more than 3 values. I wrote the code below, but it is very slow if you have a large data frame. How could I do that faster? data <- as.data.frame(matrix(c(10,11,10,13,9,10,11,10,14,9,10,10,8,12,9,10,11,10,13,9,13,13,10,13,9), nrow=5, byrow=T)) rownames(data)<-c("sample_1","sample_2","sample_3","sample_4","sample_5") >data V1 V2 V3 V4 V5 sample_1 10 11 10 13 9 sample_2 10 11 10 14 9 sample_3 10 10 8 12 9 sample_4 10 11 10 13 9 sample_5 13 13 10 13 9 tab <- data.frame(sample = NA, duplicate = NA, matches = NA) dfrow <- 1 for(i in 1:nrow(data)) { sample <- data[i, ] for(j in (i+1):nrow(data)) if(i+1 <= nrow(data)) { matches <- 0 for(V in 1:ncol(data)) { if(data[j,V] == sample[,V]) { matches <- matches + 1 } } if(matches > 3) { duplicate <- data[j, ] pair <- cbind(rownames(sample), rownames(duplicate), matches) tab[dfrow, ] <- pair dfrow <- dfrow + 1 } } } >tab sample duplicate matches 1 sample_1 sample_2 4 2 sample_1 sample_4 5 3 sample_2 sample_4 4

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• SQL SERVER – Retrieve and Explore Database Backup without Restoring Database – Idera virtual databas

  - by pinaldave

  I recently downloaded Idera’s SQL virtual database, and tested it. There are a few things about this tool which caught my attention. My Scenario It is quite common in real life that sometimes observing or retrieving older data is necessary; however, it had changed as time passed by. The full database backup was 40 GB in size, and, to restore it on our production server, it usually takes around 16 to 22 minutes, depending on the load server that is usually present. This range in time varies from one server to another as per the configuration of the computer. Some other issues we used to have are the following: When we try to restore a large 40-GB database, we needed at least that much space on our production server. Once in a while, we even had to make changes in the restored database, and use the said changed and restored database for our purpose, making it more time-consuming. My Solution I have heard a lot about the Idera’s SQL virtual database tool.. Well, right after we started to test this tool, we found out that it really delivers what it promises. Using this software was very easy and we were able to restore our database from backup in less than 2 minutes, sparing us from the usual longer time of 16–22 minutes. The needful was finished in a total of 10 minutes. Another interesting observation is that there is no need to have an additional space for restoring the database. For complete database restoration, the single additional MB on the drive is not required anymore. We can use the database in the same way as our regular database, and there is no need for any additional configuration and setup. Let us look at the most relevant points of this product based on my initial experience: Quick restoration of the database backup No additional space required for database restoration virtual database has no physical .MDF or .LDF The database which is restored is, in fact, the backup file converted in the virtual database. DDL and DML queries can be executed against this virtually restored database. Regular backup operation can be implemented against virtual database, creating a physical .bak file that can be used for future use. There was no observed degradation in performance on the original database as well the restored virtual database. Additional T-SQL queries can be let off on the virtual database. Well, this summarizes my quick review. And, as I was saying, I am very impressed with the product and I plan to explore it more. There are many features that I have noticed in this tool, which I think can be very useful if properly understood. I had taken a few screenshots using my demo database afterwards. Let us see what other things this tool can do besides the mentioned activities. I am surprised with its performance so I want to know how exactly this feature works, specifically in the matter of why it does not create any additional files and yet, it still allows update on the virtually restored database. I guess I will have to send an e-mail to the developers of Idera and try to figure this out from them. I think this tool is very useful, and it delivers a high level of performance way more than what I expected. Soon, I will write a review for additional uses of SQL virtual database.. If you are using SQL virtual database in your production environment, I am eager to learn more about it and your experience while using it. The ‘Virtual’ Part of virtual database When I set out to test this software, I thought virtual database had something to do with Hyper-V or visualization. In fact, the virtual database is a kind of database which shows up in your SQL Server Management Studio without actually restoring or even creating it. This tool creates a database in SSMS from the backup of the same database. The backup, however, works virtually the same way as original database. Potential Usage of virtual database: As soon as I described this tool to my teammate, I think his very first reaction was, “hey, if we have this then there is no need for log shipping.” I find his comment very interesting as log shipping is something where logs are moved to another server. In fact, there are no updates on the database from log; I would rather compare it with Snapshot Replication. In fact, whatever we use, snapshot replicated database can be similarly used and configured with virtual database. I totally believe that we can use it for reporting purpose. In fact, after this database was configured, I think the uses of this tool are unlimited. I will have to spend some more time studying it and will get back to you. Click on images to see larger images. virtual database Console Harddrive Space before virtual database Setup Attach Full Backup Screen Backup on Harddrive Attach Full Backup Screen with Settings virtual database Setup – less than 60 sec virtual database Setup – Online Harddrive Space after virtual database Setup Point in Time Recovery Option – Timeline View virtual database Summary No Performance Difference between Regular DB vs Virtual DB Please note that all SQL Server MVP gets free license of this software. Reference: Pinal Dave (http://blog.SQLAuthority.com), Idera (virtual database) Filed under: Database, Pinal Dave, SQL, SQL Add-On, SQL Authority, SQL Backup and Restore, SQL Data Storage, SQL Query, SQL Server, SQL Tips and Tricks, SQL Utility, SQLAuthority News, T SQL, Technology Tagged: Idera

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