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  • what are the limitations of mobile phones and web development

    - by Kieran
    simple really.. I am have been asked to do a mobile site (straight html + css (+ maybe jquery mobile later on)). The site will need to support the new type smart phone and the old type Nokia/(Symbian OS) with the web browser. Doubts and reservations aside as to anyone without a smart phone would bother visiting this site it still needs to support it. My first question is do older phones support PNG images and transparancey... But this has led me to a much broader question of what are some of the limitations of developing for older phone platforms is there anything that has caught mobile web devs out and had them scratching their head for an afternoon.. what are the limitations of mobile phones?

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  • How to emulate OOP with C?

    - by Francisco Garcia
    I would like to know which articles or books are good to use OOP concepts in C. I mean things like using function pointers to emulate classes, strict naming conventions to emulate namespaces, and things like that. Also a reference about how to code in C different types of UML diagrams would be great.

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  • What is the most obfuscated and clever code you've seen? [closed]

    - by ThibThib
    I am aware about the The International Obfuscated C Code Contest, but I am looking for obfuscated AND clever codes (specially short ones) Here is two examples (the first one is a classical one, I think) #define _ F-->00 || F-OO--; long F=00,OO=00; main(){F_OO();printf("%1.3f\n", 4.*-F/OO/OO);}F_OO() { _-_-_-_ _-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_-_-_-_ _-_-_-_-_-_-_-_-_ _-_-_-_ } and #include <unistd.h> float o=0.075,h=1.5,T,r,O,l,I;int _,L=80,s=3200;main(){for(;s%L|| (h-=o,T= -2),s;4 -(r=O*O)<(l=I*I)|++ _==L&&write(1,(--s%L?_<L?--_ %6:6:7)+"World! \n",1)&&(O=I=l=_=r=0,T+=o /2))O=I*2*O+h,I=l+T-r;} I let you compile and run them so as to understand what they are producing. Of course, I am not looking for only obfuscated code, because I guess that every code could be transformed in a way that it is not readable at all I am more looking for small codes that you can eventually understand, with some clever tricks. I will show them to my students as example of clever things that they should not do (it's always better to show clever examples rather than stupid ones...) Thanks

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  • Is "tip-of-the-day" good?

    - by Jonta
    Many programs (often large ones, like MS Office, The GIMP, Maxthon) have a feature called "tip-of-the-day". It explains a small part of the program, like this one in Maxthon: "You can hide/show the main menu bar by pressing Ctrl+F11" You can usually browse through them by clicking next. And other options provided are "Previous", "Close", "Do not show at startup". I think I like the way Maxthon used to handle this; in the browser's statusbar (down at the bottom usually, together with "Done", the progress-bar etc), there would sometimes be a small hint or tip on what else you could do with it. As Joel Spolsky wrote in his article-series "User Interface Design for Programmers", people don't like reading manuals. But we still want them to use the program, and the features they could benefit from, don't we? Therefore, I think it is useful to have such a feature, without the annoyance of the pop-up on startup. What do you think? Pop-up? Maxthonstyle? No way?

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  • What is the worst gotcha in WPF?

    - by David
    Hi, I've started to make myself a list of "WPF gotchas": things that bug me and that I had to write down to remember because I fall for them every time.... Now, I'm pretty sure you all stumbled upon similar situations at one point, and I would like you to share your experience on the subject: What is the gotcha that gets you all the time? the one you find the most annoying? (I have a few issues that seem to be without explanation, maybe your submissions will explain them) Here are a few of my "personnal" gotchas (randomly presented): For a MouseEvent to be fired even when the click is on the "transparent" background of a control (e.g. a label) and not just on the content (the Text in this case), the control's Background has to be set to "Brushes.Transparent" and not just "null" (default value for a label) A WPF DataGridCell's DataContext is the RowView to whom the cell belong, not the CellView When inside a ScrollViewer, a Scrollbar is managed by the scrollviewer itself (i.e. setting properties such as ScrollBar.Value is without effect) Key.F10 is not fired when you press "F10", instead you get Key.System and you have to go look for e.SystemKey to get the Key.F10 ... and now you're on.

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  • Optimize jQuery code

    - by Dannemannen
    Greetings, Just built some stuff with jQuery, everything works perfect(!), but I would like it to be as optimzed as possible.. what small changes can I do to my code? $(document).ready(function() { // hide the indicator, we use it later $(".indicator").hide(); // start the animation of the progressbar $(".fill").animate({ width: "50px",}, 4000, function() { $(".indicator").effect("pulsate", { times:999 }, 2000);}); // notify-me ajax function $(".btn-submit").click(function() { // get the variable email and put it in a new variable var email = $("input#mail").val(); var dataString = 'mail='+email; $.ajax({ type: "POST", url: "/mail.php", data: dataString, dataType: "json", success: function(msg){ // JSON return, lets do some magic if(msg.status == "ok") { $("#response-box").fadeIn("slow").delay(2000).fadeOut("slow"); $("#fade").fadeIn("slow").delay(2000).fadeOut("slow"); $("#response-box .inner").html("<h1>Thank you.</h1>We'll keep in touch!"); $("#mail").val("e.g. [email protected]"); } else { $("#response-box").fadeIn("slow").delay(2000).fadeOut("slow"); $("#fade").fadeIn("slow").delay(2000).fadeOut("slow"); $("#response-box .inner").html("<h1>Oops.</h1>Please try again!"); } } }); //make sure the form doesn't post return false; }); });

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  • Expanding collapsed code in Eclipse IDE

    - by rabin
    Instead of going through each (+) sign at the left and clicking them to expand the collapsed code snippets, is there a shortcut or menu item (I couldn't find it, VS has that) to expand all the collapsed code/comments at once? Thanks.

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  • Cross-platform builds with OGRE3D via CMake. Any tips?

    - by frarees
    I've been trying to compile a simple project for both OSX and Windows platforms, using OGRE3D, but I've got some problems on the way. I'm using CMake to create my platform specific project files (VS solution & Xcode project). Some problems I found are: OGRE3D source is distributed in 2 flavors, Windows sources and UNIX/OSX sources. In OSX, compiling dependencies (freetype, FreeImage and specially OIS) is such a pain. I don't know how to handle precompiled dependencies (they exist for both Win & Mac). May sound like a noob question, but I would appreciate some tips on this. Resources, forum posts, anything. There exists any "cross-platform base project for OGRE3D" on the net? Would be really helpful if someone who already managed to do this can bring some light. Btw, I'm not basing the project on OGRE3D, it's just that is the biggest library I'm probably using, so I depend a lot on it. Thanks in advantage!

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  • SQL*Plus??? - SPOOL??????(????? ???Tips-5)

    - by Yuichi.Hayashi
    SQL??????????????????????????????????????SPOOL?????????????? ???SPOOL??????????????????????????????? ????????? ????????????????????????????????????????????????????????????????????    $ sqlplus @sample.sql > /dev/null ??????????????????????????????? ??????????SPOOL????????????????? arraysize???????? arraysize???????SELECT??????fetch?????????SQL*Plus????????? ????????SPOOL????????SELECT???????????? SPOOL????     SQL> set array[size] 100 ????????fetch?100?????????????15???? ???????????????????????????????????????????????????? ????????????????????????????????????????????????????????????? ?????????????????????????????????????????????? ?????????? SPOOL?????????????1?????linesize???????????????????????????????? ????????????????????????????????????????? ????????????SPOOL????    SQL> set trims[pool] on ????????????off???????????????? ?????????? ???????????????SQL*Plus????????????1????????????????????????????????????????????????????????? ??????????????????????   (Written by Hiroyuki Nakaie) ?????SQL*Plus TIPS???????????????? Oracle SQL*Plus - ??, ??, ?????

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  • What if I have an API method and a contoller/view method with the same name in RoR?

    - by Chad Johnson
    Suppose I want to be able to view a list of products on my site by going to /product/list. Great. So this uses my 'list' view and outputs some HTML which my web browser will render. But now suppose I want to provide a REST API to my client where they can get a list of their products. So I suppose I'd have them authenticate with oAuth and then they'd call /product/list which would return a JSON array of their products. But like I said earlier, /product/list displays an HTML web page. So, I have a conflict. What is normal practice as far as providing APIs in Rails? Should I have a subdirectory, 'api', in /app/controller, and another 'product' controller? So my client would go to /api/product/list to get a list of their products? I'm a bit new to RoR, so I don't have the best grasp of the REST functionality yet, but hopefully my question makes sense.

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  • how to pass session variable to model in RoR?

    - by siulamvictor
    I used a global variable in my app for passing information before. But I got a problem and thanks everyone here suggested me to store those data in session with database. I tried, but I found that I can't access the session variable in Model. I googled and knew this is the Model normal behavior, RoR won't pass the session variable to Model. So how to pass the value of the session variable into Models? or is there any other method for my use case? I need a variable storing a value, which is required in all MVCs, and should be independent between different concurrent users. Thanks everyone. :)

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  • WP7 Tips–Part I– Media File Coding Techniques to help pass the Windows Phone 7 Marketplace Certification Requirements

    - by seaniannuzzi
    Overview Developing an application that plays media files on a Windows Phone 7 Device seems fairly straight forward.  However, what can make this a bit frustrating are the necessary requirements in order to pass the WP7 marketplace requirements so that your application can be published.  If you are new to this development, be aware of these common challenges that are likely to be made.  Below are some techniques and recommendations on how optimize your application to handle playing MP3 and/or WMA files that needs to adhere to the marketplace requirements.   Windows Phone 7 Certification Requirements Windows Phone 7 Developers Blog   Some common challenges are: Not prompting the user if another media file is playing in the background before playing your media file Not allowing the user to control the volume Not allowing the user to mute the sound Not allowing the media to be interrupted by a phone call  To keep this as simple as possible I am only going to focus on what “not to do” and what “to do” in order to implement a simple media solution. Things you will need or may be useful to you before you begin: Visual Studio 2010 Visual Studio 2010 Feature Packs Windows Phone 7 Developer Tools Visual Studio 2010 Express for Windows Phone Windows Phone Emulator Resources Silverlight 4 Tools For Visual Studio XNA Game Studio 4.0 Microsoft Expression Blend for Windows Phone Note: Please keep in mind you do not need all of these downloaded and installed, it is just easier to have all that you need now rather than add them on later.   Objective Summary Create a Windows Phone 7 – Windows Media Sample Application.  The application will implement many of the required features in order to pass the WP7 marketplace certification requirements in order to publish an application to WP7’s marketplace. (Disclaimer: I am not trying to indicate that this application will always pass as the requirements may change or be updated)   Step 1: – Create a New Windows Phone 7 Project   Step 2: – Update the Title and Application Name of your WP7 Application For this example I changed: the Title to: “DOTNETNUZZI WP7 MEDIA SAMPLE - v1.00” and the Page Title to:  “media magic”. Note: I also updated the background.   Step 3: – XAML - Media Element Preparation and Best Practice Before we begin the next step I just wanted to point out a few things that you should not do as a best practice when developing an application for WP7 that is playing music.  Please keep in mind that these requirements are not the same if you are playing Sound Effects and are geared towards playing media in the background.   If you have coded this – be prepared to change it:   To avoid a failure from the market place remove all of your media source elements from your XAML or simply create them dynamically.  To keep this simple we will remove the source and set the AutoPlay property to false to ensure that there are no media elements are active when the application is started. Proper example of the media element with No Source:   Some Additional Settings - Add XAML Support for a Mute Button   Step 4: – Boolean to handle toggle of Mute Feature Step 5: – Add Event Handler for Main Page Load   Step 6: – Add Reference to the XNA Framework   Step 7: – Add two Using Statements to Resolve the Namespace of Media and the Application Bar using Microsoft.Xna.Framework.Media; using Microsoft.Phone.Shell;   Step 8: – Add the Method to Check the Media State as Shown Below   Step 9: – Add Code to Mute the Media File Step 10: – Add Code to Play the Media File //if the state of the media has been checked you are good to go. media_sample.Play(); Note: If we tried to perform this operation at this point you will receive the following error: System.InvalidOperationException was unhandled Message=FrameworkDispatcher.Update has not been called. Regular FrameworkDispatcher.Update calls are necessary for fire and forget sound effects and framework events to function correctly. See http://go.microsoft.com/fwlink/?LinkId=193853 for details. StackTrace:        at Microsoft.Xna.Framework.FrameworkDispatcher.AddNewPendingCall(ManagedCallType callType, UInt32 arg)        at Microsoft.Xna.Framework.UserAsyncDispatcher.HandleManagedCallback(ManagedCallType managedCallType, UInt32 managedCallArgs) at Microsoft.Xna.Framework.UserAsyncDispatcher.AsyncDispatcherThreadFunction()            It is not recommended that you just add the FrameworkDispatcher.Update(); call before playing the media file. It is recommended that you implement the following class to your solution and implement this class in the app.xaml.cs file.   Step 11: – Add FrameworkDispatcher Features I recommend creating a class named XNAAsyncDispatcher and adding the following code:   After you have added the code accordingly, you can now implement this into your app.xaml.cs file as highlighted below.   Note:  If you application sound file is not playing make sure you have the proper “Build Action” set such as Content.   Running the Sample Now that we have some of the foundation created you should be able to run the application successfully.  When the application launches your sound options should be set accordingly when the “checkMediaState” method is called.  As a result the application will properly setup the media options and/or alert the user accordinglyper the certification requirements.  In addition, the sample also shows a quick way to mute the sound in your application by simply removing the URI source of the media file.  If everything successfully compiled the application should look similar to below.                 <sound playing>   Summary At this point we have a fully functional application that provides techniques on how to avoid some common challenges when working with media files and developing applications for Windows Phone 7.  The techniques mentioned above should make things a little easier and helpful in getting your WP7 application approved and published on the Marketplace.  The next blog post will be titled: WP7 Tips–Part II - How to write code that will pass the Windows Phone 7 Marketplace Requirements for Themes (light and dark). If anyone has any questions or comments please comment on this blog. 

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  • H1 Visa interview tips–What you must know before attending the interview?

    - by Gopinath
    USA’s H1 visa allows highly qualified professionals from other countries to work in America. Many IT professionals in India aspire to go to USA on H1 and work for their clients. Recently I had a chance to study H1 visa process to help one of my friends and I would like to share what I learned. With the assumption that your H1 petition is approved and you got an interview scheduled at US Embassy for your visa stamping, here are tips you must know before attending the interview Dress Code – Formals Say no to casuals or any fancy dress when you attend the interview. It’s not a party or friends home you are visiting. Consider H1 Visa interview as your job interview and dress up in formals. There is no option B for your, you must be in formals. A plain formal shirt with a matching pant is suggested for men. Tie and Suit would not be required, but if you are a professional at management level you can consider wearing suit. Women can wear either formal Salwar or formal pant-shirt. Avoid heavy jewellery, wear what is must as per your tradition or culture. Body Language -  Smile on your face Your body language reflects what you are and what’s going on in your mind. Don’t be nervous or restless, be relaxed and wear a beautiful smile on your face. A smile is a curve that sets everything straight. When you are called for the interview, greet the interviewer with a beautiful smile. Say Good Morning/Afternoon/Evening depending on time you are visiting them. Whenever appropriate say Thank You. Generally American professionals are very friendly people and they reciprocate for your greetings. Make sure that you make them comfortable to start the interview. Carry original documents in a separate folder I don’t want to talk much about the documents that are required for your H1B interview as it’s big subject on it’s own and it requires a separate post. I assume that your consultant or employer helped you in gathering all the required documents like – petition, DS 160 forms, education & job related documents, resume, interview call letters, client letters, etc. For all the documents you are going to submit at the interview make sure that you have originals in a separate folder.  If required interviewer may ask you show the originals of any of the document you submitted for visa processing. Don’t mix the original documents with the documents you need to submit for interview. Have a separate folder for them. For those who are going to stamping along with their spouse and children, they need to carry few extra original documents like – marriage certificate, marriage photos(30 numbers)/album, birth certificates, passports, education and profession related certificates of the spouse and children. Know your role & responsibilities The interviewer will ask you questions on your roles and responsibilities at client location. Be clear what is your day to day tasks at client place and prepared to face detailed questions on the same. When asked explain clearly and also make sure what you say is inline with what is mentioned in your petition and client invitation letter. At times they may ask you questions specific to the project/technology you are going to work. So doing some homework in this area will help you easily answer the questions. Failing to answer basic questions on your role & responsibilities may result in rejection. You work for your Employer at Client location but NOT FOR CLIENT One of the important things to keep in mind that you work for your employer and you are being deputed to client location on a work visa.  Your employer is going to be solely responsible for your salary, work, promotion, pay hikes or what so ever during your stay at USA. Your client will not be responsible for anything. Lets say you are employed with Company X in India and they are applying for H1B to work at your client(ex: Microsoft) in USA, you must keep in my mind that Microsoft is not your employer. Microsoft will not pay your salaries or responsible for any employment related activities. Company X will be solely responsible for all your employer related activities. If you don’t get this correctly and say to Visa interviewer that your client is responsible, then you may get into troubles. Know your client It’s always good to know the clients with whom you are going to work in USA and their business. If your client is a well know organisation then you may not get many questions from interviewer else you need to be well prepared to provide details like – nature of business, location, size of the organisation, etc.  Get to know the basic details about your client and be confident while providing those details to the interviewer. Also make sure that you never talk about any confidential details of your client projects and business. Revealing confidential details of your client may land your job itself in soup. Make sure that your spouse is also in sync with you If you’ve applied a H4 visa for your spouse along with your H1, make sure that spouse is in sync with you. Your spouse also should know the basic details of your job, your employer, client and location where you will be travelling. Your spouse should also be prepared to answers questions related to marriage, their profession(if working), kids, education, etc. Interviewers will try to asses your spouse communication skills, whereabouts while staying in USA and would they prefer to work USA or not. On H4, which is a dependent visa, your spouse is not allowed to work in USA and at any point your spouse should not show the intentions to search for work in USA. Less luggage more comfort You would have definitely heard that there are lot of restrictions on what you can carry along with you to an US Embassy while attending the interview. To be frank it’s not good to say there are many restrictions, but there are a hell a lot of restrictions. There are unbelievable restrictions and it’s for the safety of everyone. You are not allowed to carry mobile phones, CD/DVDs, USBs, bank cards, cameras, cosmetics, food(except baby food), water, wallets, backpacks, sealed covers, etc. Trust me most of the things we carry with us regularly every day are not allowed inside. As there are 100s of restrictions, it would be easier if you understand what you can carry along with you and just carry them alone. Ask your employer/consultant to provide you a checklist of items that you can carry. Most what you would require are H1B related documents provided by the employer/consultant Photographs All original documents supporting your H1B Passports Some cash for your travel expenses (avoid coins) Any important phone number / details written in a paper(like your cab driver number, etc.) If you carry restricted stuff then you will be stopped at security checks, you have to find people who can safely keep all the restricted items. Due to heavy restrictions in and around the US Embassy you will not find any  place to keep your luggage. So just carry the bare minimum things required so that you feel more comfortable. Useful Links THE U.S. NON IMMIGRANT VISA APPLICATION PROCESS U.S VISA SECURITY REGULATIONS GENERAL FAQS Hope this information is helpful to you and best of luck for your interview. Creative commons Image credit: Flickr/ alexfrance, vinothchandar. hughelectronic, architratan, striatic

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  • Entity Framework v1 &hellip; Brief Synopsis and Tips &ndash; Part 2

    - by Rohit Gupta
    Using Entity Framework with ASMX Web sErvices and WCF Web Service: If you use ASMX WebService to expose Entity objects from Entity Framework... then the ASMX Webservice does not  include object graphs, one work around is to use Facade pattern or to use WCF Service. The other important aspect of using ASMX Web Services along with Entity Framework is that the ASMX Client is not aware of the existence of EF v1 since the client solely deals with C# objects (not EntityObjects or ObjectContext). Since the client is not aware of the ObjectContext hence the client cannot participate in change tracking since the client only receives the Current Values and not the Orginal values when the service sends the the Entity objects to the client. Thus there are 2 drawbacks to using EntityFramework with ASMX Web Service: 1. Object state is not maintained... so to overcome this limitation we need insert/update single entity at a time and retrieve the original values for the entity being updated on the server/service end before calling Save Changes. 2. ASMX does not maintain object graphs... i.e. Customer.Reservations or Customer.Reservations.Trip relationships are not maintained. Thus you need to send these relationships separately from service to client. WCF Web Service overcomes the object graph limitation of ASMX Web Service, but we need to insure that we are populating all the non-null scalar properties of all the objects in the object graph before calling Update. WCF Web service still cannot overcome the second limitation of tracking changes to entities at the client end. Also note that the "Customer" class in the Client is very different from the "Customer" class in the Entity Framework Model Entities. They are incompatible with each other hence we cannot cast one to the other. However the .NET Framework translates the client "Customer" Entity to the EFv1 Model "customer" Entity once the entity is serialzed back on the ASMX server end. If you need change tracking enabled on the client then we need to use WCF Data Services which is available with VS 2010. ====================================================================================================== In WCF when adding an object that has relationships, the framework assumes that every object in the object graph needs to be added to store. for e.g. in a Customer.Reservations.Trip object graph, when a Customer Entity is added to the store, the EFv1 assumes that it needs to a add a Reservations collection and also Trips for each Reservation. Thus if we need to use existing Trips for reservations then we need to insure that we null out the Trip object reference from Reservations and set the TripReference to the EntityKey of the desired Trip instead. ====================================================================================================== Understanding Relationships and Associations in EFv1 The Golden Rule of EF is that it does not load entities/relationships unless you ask it to explicitly do so. However there is 1 exception to this rule. This exception happens when you attach/detach entities from the ObjectContext. If you detach an Entity in a ObjectGraph from the ObjectContext, then the ObjectContext removes the ObjectStateEntry for this Entity and all the relationship Objects associated with this Entity. For e.g. in a Customer.Order.OrderDetails if the Customer Entity is detached from the ObjectContext then you cannot traverse to the Order and OrderDetails Entities (that still exist in the ObjectContext) from the Customer Entity(which does not exist in the Object Context) Conversely, if you JOIN a entity that is not in the ObjectContext with a Entity that is in the ObjContext then the First Entity will automatically be added to the ObjContext since relationships for the 2 Entities need to exist in the ObjContext. ========================================================= You cannot attach an EntityCollection to an entity through its navigation property for e.g. you cannot code myContact.Addresses = myAddressEntityCollection ========================================================== Cascade Deletes in EDM: The Designer does not support specifying cascase deletes for a Entity. To enable cascasde deletes on a Entity in EDM use the Association definition in CSDL for the Entity. for e.g. SalesOrderDetail (SOD) has a Foreign Key relationship with SalesOrderHeader (SalesOrderHeader 1 : SalesOrderDetail *) if you specify a cascade Delete on SalesOrderHeader Entity then calling deleteObject on SalesOrderHeader (SOH) Entity will send delete commands for SOH record and all the SOD records that reference the SOH record. ========================================================== As a good design practise, if you use Cascade Deletes insure that Cascade delete facet is used both in the EDM as well as in the database. Even though it is not absolutely mandatory to have Cascade deletes on both Database and EDM (since you can see that just the Cascade delete spec on the SOH Entity in EDM will insure that SOH record and all related SOD records will be deleted from the database ... even though you dont have cascade delete configured in the database in the SOD table) ============================================================== Maintaining relationships in Code When Setting a Navigation property of a Entity (for e.g. setting the Contact Navigation property of Address Entity) the following rules apply : If both objects are detached, no relationship object will be created. You are simply setting a property the CLR way. If both objects are attached, a relationship object will be created. If only one of the objects is attached, the other will become attached and a relationship object will be created. If that detached object is new, when it is attached to the context its EntityState will be Added. One important rule to remember regarding synchronizing the EntityReference.Value and EntityReference.EntityKey properties is that when attaching an Entity which has a EntityReference (e.g. Address Entity with ContactReference) the Value property will take precedence and if the Value and EntityKey are out of sync, the EntityKey will be updated to match the Value. ====================================================== If you call .Load() method on a detached Entity then the .Load() operation will throw an exception. There is one exception to this rule. If you load entities using MergeOption.NoTracking, you will be able to call .Load() on such entities since these Entities are accessible by the ObjectContext. So the bottomline is that we need Objectontext to be able to call .Load() method to do deffered loading on EntityReference or EntityCollection. Another rule to remember is that you cannot call .Load() on entities that have a EntityState.Added State since the ObjectContext uses the EntityKey of the Primary (Parent) Entity when loading the related (Child) Entity (and not the EntityKey of the child (even if the EntityKey of the child is present before calling .Load()) ====================================================== You can use ObjContext.Add() to add a entity to the ObjContext and set the EntityState of the new Entity to EntityState.Added. here no relationships are added/updated. You can also use EntityCollection.Add() method to add an entity to another entity's related EntityCollection for e.g. contact has a Addresses EntityCollection so to add a new address use contact.Addresses.Add(newAddress) to add a new address to the Addresses EntityCollection. Note that if the entity does not already exist in the ObjectContext then calling contact.Addresses.Add(myAddress) will cause a new Address Entity to be added to the ObjContext with EntityState.Added and it will also add a RelationshipEntry (a relationship object) with EntityState.Added which connects the Contact (contact) with the new address newAddress. Note that if the entity already exists in the Objectcontext (being part theOtherContact.Addresses Collection), then calling contact.Addresses.Add(existingAddress) will add 2 RelationshipEntry objects to the ObjectStateEntry Collection, one with EntityState.Deleted and the other with EntityState.Added. This implies that the existingAddress Entity is removed from the theOtherContact.Addresses Collection and Added to the contact.Addresses Collection..effectively reassigning the address entity from the theOtherContact to "contact". This is called moving an existing entity to a new object graph. ====================================================== You usually use ObjectContext.Attach() and EntityCollection.Attach() methods usually when you need to reconstruct the ObjectGraph after deserializing the objects as received from a ASMX Web Service Client. Attach is usually used to connect existing Entities in the ObjectContext. When EntityCollection.Attach() is called the EntityState of the RelationshipEntry (the relationship object) remains as EntityState.unchanged whereas when EntityCollection.Add() method is called the EntityState of the relationship object changes to EntityState.Added or EntityState.Deleted as the situation demands. ========================================================= LINQ To Entities Tips: Select Many does Inner Join by default.   for e.g. from c in Contact from a in c.Address select c ... this will do a Inner Join between the Contacts and Addresses Table and return only those Contacts that have a Address. ======================================================== Group Joins Do LEFT Join by default. e.g. from a in Address join c in Contact ON a.Contact.ContactID == c.ContactID Into g WHERE a.CountryRegion == "US" select g; This query will do a left join on the Contact table and return contacts that have a address in "US" region The following query : from c in Contact join a in Address.Where(a1 => a1.CountryRegion == "US") on c.ContactID  equals a.Contact.ContactID into addresses select new {c, addresses} will do a left join on the Address table and return All Contacts. In these Contacts only those will have its Address EntityCollection Populated which have a Address in the "US" region, the other contacts will have 0 Addresses in the Address collection (even if addresses for those contacts exist in the database but are in a different region) ======================================================== Linq to Entities does not support DefaultIfEmpty().... instead use .Include("Address") Query Builder method to do a Left JOIN or use Group Joins if you need more control like Filtering on the Address EntityCollection of Contact Entity =================================================================== Use CreateSourceQuery() on the EntityReference or EntityCollection if you need to add filters during deferred loading of Entities (Deferred loading in EFv1 happens when you call Load() method on the EntityReference or EntityCollection. for e.g. var cust=context.Contacts.OfType<Customer>().First(); var sq = cust.Reservations.CreateSourceQuery().Where(r => r.ReservationDate > new DateTime(2008,1,1)); cust.Reservations.Attach(sq); This populates only those reservations that are older than Jan 1 2008. This is the only way (in EFv1) to Attach a Range of Entities to a EntityCollection using the Attach() method ================================================================== If you need to get the Foreign Key value for a entity e.g. to get the ContactID value from a Address Entity use this :                                address.ContactReference.EntityKey.EntityKeyValues.Where(k=> k.Key == "ContactID")

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  • Entity Framework v1 &ndash; tips and Tricks Part 3

    - by Rohit Gupta
    General Tips on Entity Framework v1 & Linq to Entities: ToTraceString() If you need to know the underlying SQL that the EF generates for a Linq To Entities query, then use the ToTraceString() method of the ObjectQuery class. (or use LINQPAD) Note that you need to cast the LINQToEntities query to ObjectQuery before calling TotraceString() as follows: 1: string efSQL = ((ObjectQuery)from c in ctx.Contact 2: where c.Address.Any(a => a.CountryRegion == "US") 3: select c.ContactID).ToTraceString(); ================================================================================ MARS or MultipleActiveResultSet When you create a EDM Model (EDMX file) from the database using Visual Studio, it generates a connection string with the same name as the name of the EntityContainer in CSDL. In the ConnectionString so generated it sets the MultipleActiveResultSet attribute to true by default. So if you are running the following query then it streams multiple readers over the same connection: 1: using (BAEntities context = new BAEntities()) 2: { 3: var cons = 4: from con in context.Contacts 5: where con.FirstName == "Jose" 6: select con; 7: foreach (var c in cons) 8: { 9: if (c.AddDate < new System.DateTime(2007, 1, 1)) 10: { 11: c.Addresses.Load(); 12: } 13: } 14: } ================================================================================= Explicitly opening and closing EntityConnection When you call ToList() or foreach on a LINQToEntities query the EF automatically closes the connection after all the records from the query have been consumed. Thus if you need to run many LINQToEntities queries over the same connection then explicitly open and close the connection as follows: 1: using (BAEntities context = new BAEntities()) 2: { 3: context.Connection.Open(); 4: var cons = from con in context.Contacts where con.FirstName == "Jose" 5: select con; 6: var conList = cons.ToList(); 7: var allCustomers = from con in context.Contacts.OfType<Customer>() 8: select con; 9: var allcustList = allCustomers.ToList(); 10: context.Connection.Close(); 11: } ====================================================================== Dispose ObjectContext only if required After you retrieve entities using the ObjectContext and you are not explicitly disposing the ObjectContext then insure that your code does consume all the records from the LinqToEntities query by calling .ToList() or foreach statement, otherwise the the database connection will remain open and will be closed by the garbage collector when it gets to dispose the ObjectContext. Secondly if you are making updates to the entities retrieved using LinqToEntities then insure that you dont inadverdently dispose of the ObjectContext after the entities are retrieved and before calling .SaveChanges() since you need the SAME ObjectContext to keep track of changes made to the Entities (by using ObjectStateEntry objects). So if you do need to explicitly dispose of the ObjectContext do so only after calling SaveChanges() and only if you dont need to change track the entities retrieved any further. ======================================================================= SQL InjectionAttacks under control with EFv1 LinqToEntities and LinqToSQL queries are parameterized before they are sent to the DB hence they are not vulnerable to SQL Injection attacks. EntitySQL may be slightly vulnerable to attacks since it does not use parameterized queries. However since the EntitySQL demands that the query be valid Entity SQL syntax and valid native SQL syntax at the same time. So the only way one can do a SQLInjection Attack is by knowing the SSDL of the EDM Model and be able to write the correct EntitySQL (note one cannot append regular SQL since then the query wont be a valid EntitySQL syntax) and append it to a parameter. ====================================================================== Improving Performance You can convert the EntitySets and AssociationSets in a EDM Model into precompiled Views using the edmgen utility. for e.g. the Customer Entity can be converted into a precompiled view using edmgen and all LinqToEntities query against the contaxt.Customer EntitySet will use the precompiled View instead of the EntitySet itself (the same being true for relationships (EntityReference & EntityCollections of a Entity)). The advantage being that when using precompiled views the performance will be much better. The syntax for generating precompiled views for a existing EF project is : edmgen /mode:ViewGeneration /inssdl:BAModel.ssdl /incsdl:BAModel.csdl /inmsl:BAModel.msl /p:Chap14.csproj Note that this will only generate precompiled views for EntitySets and Associations and not for existing LinqToEntities queries in the project.(for that use CompiledQuery.Compile<>) Secondly if you have a LinqToEntities query that you need to run multiple times, then one should precompile the query using CompiledQuery.Compile method. The CompiledQuery.Compile<> method accepts a lamda expression as a parameter, which denotes the LinqToEntities query  that you need to precompile. The following is a example of a lamda that we can pass into the CompiledQuery.Compile() method 1: Expression<Func<BAEntities, string, IQueryable<Customer>>> expr = (BAEntities ctx1, string loc) => 2: from c in ctx1.Contacts.OfType<Customer>() 3: where c.Reservations.Any(r => r.Trip.Destination.DestinationName == loc) 4: select c; Then we call the Compile Query as follows: 1: var query = CompiledQuery.Compile<BAEntities, string, IQueryable<Customer>>(expr); 2:  3: using (BAEntities ctx = new BAEntities()) 4: { 5: var loc = "Malta"; 6: IQueryable<Customer> custs = query.Invoke(ctx, loc); 7: var custlist = custs.ToList(); 8: foreach (var item in custlist) 9: { 10: Console.WriteLine(item.FullName); 11: } 12: } Note that if you created a ObjectQuery or a Enitity SQL query instead of the LINQToEntities query, you dont need precompilation for e.g. 1: An Example of EntitySQL query : 2: string esql = "SELECT VALUE c from Contacts AS c where c is of(BAGA.Customer) and c.LastName = 'Gupta'"; 3: ObjectQuery<Customer> custs = CreateQuery<Customer>(esql); 1: An Example of ObjectQuery built using ObjectBuilder methods: 2: from c in Contacts.OfType<Customer>().Where("it.LastName == 'Gupta'") 3: select c This is since the Query plan is cached and thus the performance improves a bit, however since the ObjectQuery or EntitySQL query still needs to materialize the results into Entities hence it will take the same amount of performance hit as with LinqToEntities. However note that not ALL EntitySQL based or QueryBuilder based ObjectQuery plans are cached. So if you are in doubt always create a LinqToEntities compiled query and use that instead ============================================================ GetObjectStateEntry Versus GetObjectByKey We can get to the Entity being referenced by the ObjectStateEntry via its Entity property and there are helper methods in the ObjectStateManager (osm.TryGetObjectStateEntry) to get the ObjectStateEntry for a entity (for which we know the EntityKey). Similarly The ObjectContext has helper methods to get an Entity i.e. TryGetObjectByKey(). TryGetObjectByKey() uses GetObjectStateEntry method under the covers to find the object, however One important difference between these 2 methods is that TryGetObjectByKey queries the database if it is unable to find the object in the context, whereas TryGetObjectStateEntry only looks in the context for existing entries. It will not make a trip to the database ============================================================= POCO objects with EFv1: To create POCO objects that can be used with EFv1. We need to implement 3 key interfaces: IEntityWithKey IEntityWithRelationships IEntityWithChangeTracker Implementing IEntityWithKey is not mandatory, but if you dont then we need to explicitly provide values for the EntityKey for various functions (for e.g. the functions needed to implement IEntityWithChangeTracker and IEntityWithRelationships). Implementation of IEntityWithKey involves exposing a property named EntityKey which returns a EntityKey object. Implementation of IEntityWithChangeTracker involves implementing a method named SetChangeTracker since there can be multiple changetrackers (Object Contexts) existing in memory at the same time. 1: public void SetChangeTracker(IEntityChangeTracker changeTracker) 2: { 3: _changeTracker = changeTracker; 4: } Additionally each property in the POCO object needs to notify the changetracker (objContext) that it is updating itself by calling the EntityMemberChanged and EntityMemberChanging methods on the changeTracker. for e.g.: 1: public EntityKey EntityKey 2: { 3: get { return _entityKey; } 4: set 5: { 6: if (_changeTracker != null) 7: { 8: _changeTracker.EntityMemberChanging("EntityKey"); 9: _entityKey = value; 10: _changeTracker.EntityMemberChanged("EntityKey"); 11: } 12: else 13: _entityKey = value; 14: } 15: } 16: ===================== Custom Property ==================================== 17:  18: [EdmScalarPropertyAttribute(IsNullable = false)] 19: public System.DateTime OrderDate 20: { 21: get { return _orderDate; } 22: set 23: { 24: if (_changeTracker != null) 25: { 26: _changeTracker.EntityMemberChanging("OrderDate"); 27: _orderDate = value; 28: _changeTracker.EntityMemberChanged("OrderDate"); 29: } 30: else 31: _orderDate = value; 32: } 33: } Finally you also need to create the EntityState property as follows: 1: public EntityState EntityState 2: { 3: get { return _changeTracker.EntityState; } 4: } The IEntityWithRelationships involves creating a property that returns RelationshipManager object: 1: public RelationshipManager RelationshipManager 2: { 3: get 4: { 5: if (_relManager == null) 6: _relManager = RelationshipManager.Create(this); 7: return _relManager; 8: } 9: } ============================================================ Tip : ProviderManifestToken – change EDMX File to use SQL 2008 instead of SQL 2005 To use with SQL Server 2008, edit the EDMX file (the raw XML) changing the ProviderManifestToken in the SSDL attributes from "2005" to "2008" ============================================================= With EFv1 we cannot use Structs to replace a anonymous Type while doing projections in a LINQ to Entities query. While the same is supported with LINQToSQL, it is not with LinqToEntities. For e.g. the following is not supported with LinqToEntities since only parameterless constructors and initializers are supported in LINQ to Entities. (the same works with LINQToSQL) 1: public struct CompanyInfo 2: { 3: public int ID { get; set; } 4: public string Name { get; set; } 5: } 6: var companies = (from c in dc.Companies 7: where c.CompanyIcon == null 8: select new CompanyInfo { Name = c.CompanyName, ID = c.CompanyId }).ToList(); ;

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  • ADF TaskFlows Communications

    - by raghu.yadav
    Here is the list of various ADF Taskflows communication examples. http://www.oracle.com/technology/products/jdev/tips/fnimphius/CtxEvent/CtxEvent.html http://thepeninsulasedge.com/frank_nimphius/2008/02/07/adf-faces-rc-refreshing-a-table-ui-from-a-contextual-event/ http://www.oracle.com/technology/products/jdev/tips/fnimphius/generictreeselectionlistener/index.html http://www.oracle.com/technology/products/jdev/tips/fnimphius/syncheditformwithtree/index.html http://biemond.blogspot.com/2009/01/passing-adf-events-between-task-flow.html http://www.oracle.com/technology/products/jdev/tips/fnimphius/opentaskflowintab/index.html http://lucbors.blogspot.com/2010/03/adf-11g-contextual-event-framework.html http://thepeninsulasedge.com/blog/?cat=2 http://www.ora600.be/news/adf-contextual-events-11g-r1-ps1

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  • How to get bit rotation function to accept any bit size?

    - by calccrypto
    i have these 2 functions i got from some other code def ROR(x, n): mask = (2L**n) - 1 mask_bits = x & mask return (x >> n) | (mask_bits << (32 - n)) def ROL(x, n): return ROR(x, 32 - n) and i wanted to use them in a program, where 16 bit rotations are required. however, there are also other functions that require 32 bit rotations, so i wanted to leave the 32 in the equation, so i got: def ROR(x, n, bits = 32): mask = (2L**n) - 1 mask_bits = x & mask return (x >> n) | (mask_bits << (bits - n)) def ROL(x, n, bits = 32): return ROR(x, bits - n) however, the answers came out wrong when i tested this set out. yet, the values came out correctly when the code is def ROR(x, n): mask = (2L**n) - 1 mask_bits = x & mask return (x >> n) | (mask_bits << (16 - n)) def ROL(x, n,bits): return ROR(x, 16 - n) what is going on and how do i fix this?

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  • How select the rest of the word in incremental search in Eclipse?

    - by arberg
    When in incremental search mode in Eclipse, is there a way to select the rest of the word? For example, suppose I want to find the word “handleReservationGranted”. I type Ctrl-f to enter incremental search mode, and start typing the letters “han”. Now suppose I have found the beginning of “handleReservationGranted”. In my search box I have “han”, but I would now like to be able to select the rest of the word, so that the search box contains “handleReservationGranted” instead of “han”. In Xemacs, I can type Ctrl-s, type “han”, and then type Ctrl-w. Now my search term is “handleReservationGranted”, and not “han”. So now if I press Ctrl-s, I find the next occurrence of “handleReservationGranted”. I frequently prefer the incremental search over the search dialog, as the search dialog takes too much space on my screen, and most annoying it frequently hides the found matches. I am using Eclipse Galileo (3.5.2). Ctrl-Shift-L gives me the list of possible shortcuts in the given context, but none seems to fit what I'm looking for.

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  • What are some general tips to make InnoDB for MySQL perform at its highest?

    - by James Simpson
    I've been using MyISAM exclusively for several years now and know the ins-and-outs pretty well of how to optimize it, but I've just recently started using InnoDB for some of my tables and don't know that much about it. What are some general tips to help improve the performance of these InnoDB tables (they were converted from MyISAM and have anywhere from 100k - 2M rows and most won't use transactions).

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  • Entity Framework version 1- Brief Synopsis and Tips &ndash; Part 1

    - by Rohit Gupta
    To Do Eager loading use Projections (for e.g. from c in context.Contacts select c, c.Addresses)  or use Include Query Builder Methods (Include(“Addresses”)) If there is multi-level hierarchical Data then to eager load all the relationships use Include Query Builder methods like customers.Include("Order.OrderDetail") to include Order and OrderDetail collections or use customers.Include("Order.OrderDetail.Location") to include all Order, OrderDetail and location collections with a single include statement =========================================================================== If the query uses Joins then Include() Query Builder method will be ignored, use Nested Queries instead If the query does projections then Include() Query Builder method will be ignored Use Address.ContactReference.Load() OR Contact.Addresses.Load() if you need to Deferred Load Specific Entity – This will result in extra round trips to the database ObjectQuery<> cannot return anonymous types... it will return a ObjectQuery<DBDataRecord> Only Include method can be added to Linq Query Methods Any Linq Query method can be added to Query Builder methods. If you need to append a Query Builder Method (other than Include) after a LINQ method  then cast the IQueryable<Contact> to ObjectQuery<Contact> and then append the Query Builder method to it =========================================================================== Query Builder methods are Select, Where, Include Methods which use Entity SQL as parameters e.g. "it.StartDate, it.EndDate" When Query Builder methods do projection then they return ObjectQuery<DBDataRecord>, thus to iterate over this collection use contact.Item[“Name”].ToString() When Linq To Entities methods do projection, they return collection of anonymous types --- thus the collection is strongly typed and supports Intellisense EF Object Context can track changes only on Entities, not on Anonymous types. If you use a Defining Query for a EntitySet then the EntitySet becomes readonly since a Defining Query is the same as a View (which is treated as a ReadOnly by default). However if you want to use this EntitySet for insert/update/deletes then we need to map stored procs (as created in the DB) to the insert/update/delete functions of the Entity in the Designer You can use either Execute method or ToList() method to bind data to datasources/bindingsources If you use the Execute Method then remember that you can traverse through the ObjectResult<> collection (returned by Execute) only ONCE. In WPF use ObservableCollection to bind to data sources , for keeping track of changes and letting EF send updates to the DB automatically. Use Extension Methods to add logic to Entities. For e.g. create extension methods for the EntityObject class. Create a method in ObjectContext Partial class and pass the entity as a parameter, then call this method as desired from within each entity. ================================================================ DefiningQueries and Stored Procedures: For Custom Entities, one can use DefiningQuery or Stored Procedures. Thus the Custom Entity Collection will be populated using the DefiningQuery (of the EntitySet) or the Sproc. If you use Sproc to populate the EntityCollection then the query execution is immediate and this execution happens on the Server side and any filters applied will be applied in the Client App. If we use a DefiningQuery then these queries are composable, meaning the filters (if applied to the entityset) will all be sent together as a single query to the DB, returning only filtered results. If the sproc returns results that cannot be mapped to existing entity, then we first create the Entity/EntitySet in the CSDL using Designer, then create a dummy Entity/EntitySet using XML in the SSDL. When creating a EntitySet in the SSDL for this dummy entity, use a TSQL that does not return any results, but does return the relevant columns e.g. select ContactID, FirstName, LastName from dbo.Contact where 1=2 Also insure that the Entity created in the SSDL uses the SQL DataTypes and not .NET DataTypes. If you are unable to open the EDMX file in the designer then note the Errors ... they will give precise info on what is wrong. The Thrid option is to simply create a Native Query in the SSDL using <Function Name="PaymentsforContact" IsComposable="false">   <CommandText>SELECT ActivityId, Activity AS ActivityName, ImagePath, Category FROM dbo.Activities </CommandText></FuncTion> Then map this Function to a existing Entity. This is a quick way to get a custom Entity which is regular Entity with renamed columns or additional columns (which are computed columns). The disadvantage to using this is that It will return all the rows from the Defining query and any filter (if defined) will be applied only at the Client side (after getting all the rows from DB). If you you DefiningQuery instead then we can use that as a Composable Query. The Fourth option (for mapping a READ stored proc results to a non-existent Entity) is to create a View in the Database which returns all the fields that the sproc also returns, then update the Model so that the model contains this View as a Entity. Then map the Read Sproc to this View Entity. The other option would be to simply create the View and remove the sproc altogether. ================================================================ To Execute a SProc that does not return a entity, use a EntityCommand to execute that proc. You cannot call a sproc FunctionImport that does not return Entities From Code, the only way is to use SSDL function calls using EntityCommand.  This changes with EntityFramework Version 4 where you can return Scalar Types, Complex Types, Entities or NonQuery ================================================================ UDF when created as a Function in SSDL, we need to set the Name & IsComposable properties for the Function element. IsComposable is always false for Sprocs, for UDF's set this to true. You cannot call UDF "Function" from within code since you cannot import a UDF Function into the CSDL Model (with Version 1 of EF). only stored procedures can be imported and then mapped to a entity ================================================================ Entity Framework requires properties that are involved in association mappings to be mapped in all of the function mappings for the entity (Insert, Update and Delete). Because Payment has an association to Reservation... hence we need to pass both the paymentId and reservationId to the Delete sproc even though just the paymentId is the PK on the Payment Table. ================================================================ When mapping insert, update and delete procs to a Entity, insure that all the three or none are mapped. Further if you have a base class and derived class in the CSDL, then you must map (ins, upd, del) sprocs to all parent and child entities in the inheritance relationship. Note that this limitation that base and derived entity methods must all must be mapped does not apply when you are mapping Read Stored Procedures.... ================================================================ You can write stored procedures SQL directly into the SSDL by creating a Function element in the SSDL and then once created, you can map this Function to a CSDL Entity directly in the designer during Function Import ================================================================ You can do Entity Splitting such that One Entity maps to multiple tables in the DB. For e.g. the Customer Entity currently derives from Contact Entity...in addition it also references the ContactPersonalInfo Entity. One can copy all properties from the ContactPersonalInfo Entity into the Customer Entity and then Delete the CustomerPersonalInfo entity, finall one needs to map the copied properties to the ContactPersonalInfo Table in Table Mapping (by adding another table (ContactPersonalInfo) to the Table Mapping... this is called Entity Splitting. Thus now when you insert a Customer record, it will automatically create SQL to insert records into the Contact, Customers and ContactPersonalInfo tables even though you have a Single Entity called Customer in the CSDL =================================================================== There is Table by Type Inheritance where another EDM Entity can derive from another EDM entity and absorb the inherted entities properties, for example in the Break Away Geek Adventures EDM, the Customer entity derives (inherits) from the Contact Entity and absorbs all the properties of Contact entity. Thus when you create a Customer Entity in Code and then call context.SaveChanges the Object Context will first create the TSQL to insert into the Contact Table followed by a TSQL to insert into the Customer table =================================================================== Then there is the Table per Hierarchy Inheritance..... where different types are created based on a condition (similar applying a condition to filter a Entity to contain filtered records)... the diference being that the filter condition populates a new Entity Type (derived from the base Entity). In the BreakAway sample the example is Lodging Entity which is a Abstract Entity and Then Resort and NonResort Entities which derive from Lodging Entity and records are filtered based on the value of the Resort Boolean field =================================================================== Then there is Table per Concrete Type Hierarchy where we create a concrete Entity for each table in the database. In the BreakAway sample there is a entity for the Reservation table and another Entity for the OldReservation table even though both the table contain the same number of fields. The OldReservation Entity can then inherit from the Reservation Entity and configure the OldReservation Entity to remove all Scalar Properties from the Entity (since it inherits the properties from Reservation and filters based on ReservationDate field) =================================================================== Complex Types (Complex Properties) Entities in EF can also contain Complex Properties (in addition to Scalar Properties) and these Complex Properties reference a ComplexType (not a EntityType) DropdownList, ListBox, RadioButtonList, CheckboxList, Bulletedlist are examples of List server controls (not data bound controls) these controls cannot use Complex properties during databinding, they need Scalar Properties. So if a Entity contains Complex properties and you need to bind those to list server controls then use projections to return Scalar properties and bind them to the control (the disadvantage is that projected collections are not tracked by the Object Context and hence cannot persist changes to the projected collections bound to controls) ObjectDataSource and EntityDataSource do account for Complex properties and one can bind entities with Complex Properties to Data Source controls and they will be tracked for changes... with no additional plumbing needed to persist changes to these collections bound to controls So DataBound controls like GridView, FormView need to use EntityDataSource or ObjectDataSource as a datasource for entities that contain Complex properties so that changes to the datasource done using the GridView can be persisted to the DB (enabling the controls for updates)....if you cannot use the EntityDataSource you need to flatten the ComplexType Properties using projections With EF Version 4 ComplexTypes are supported by the Designer and can add/remove/compose Complex Types directly using the Designer =================================================================== Conditional Mapping ... is like Table per Hierarchy Inheritance where Entities inherit from a base class and then used conditions to populate the EntitySet (called conditional Mapping). Conditional Mapping has limitations since you can only use =, is null and IS NOT NULL Conditions to do conditional mapping. If you need more operators for filtering/mapping conditionally then use QueryView(or possibly Defining Query) to create a readonly entity. QueryView are readonly by default... the EntitySet created by the QueryView is enabled for change tracking by the ObjectContext, however the ObjectContext cannot create insert/update/delete TSQL statements for these Entities when SaveChanges is called since it is QueryView. One way to get around this limitation is to map stored procedures for the insert/update/delete operations in the Designer. =================================================================== Difference between QueryView and Defining Query : QueryView is defined in the (MSL) Mapping File/section of the EDM XML, whereas the DefiningQuery is defined in the store schema (SSDL). QueryView is written using Entity SQL and is this database agnostic and can be used against any database/Data Layer. DefiningQuery is written using Database Lanaguage i.e. TSQL or PSQL thus you have more control =================================================================== Performance: Lazy loading is deferred loading done automatically. lazy loading is supported with EF version4 and is on by default. If you need to turn it off then use context.ContextOptions.lazyLoadingEnabled = false To improve Performance consider PreCompiling the ObjectQuery using the CompiledQuery.Compile method

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  • Any tips for designing the invoicing/payment system of a SaaS?

    - by Alexandru Trandafir Catalin
    The SaaS is for real estate companies, and they can pay a monthly fee that will offer them 1000 publications but they can also consume additional publications or other services that will appear on their bill as extras. On registration the user can choose one of the 5 available plans that the only difference will be the quantity of publications their plan allows them to make. But they can pass that limit if they wish, and additional payment will be required on the next bill. A publication means: Publishing a property during one day, for 1 whole month would be: 30 publications. And 5 properties during one day would be 5 publications. So basically the user can: Make publications (already paid in the monthly fee, extra payment only if it passes the limit) Highlight that publication (extra payment) Publish on other websites or printed catalogues (extra payment) Doubts: How to handle modifications in pricing plans? Let's say quantities change, or you want to offer some free stuff. How to handle unpaid invoices? I mean, freeze the service until the payment has been done and then resume it. When to make the invoices? The idea is to make one invoice for the monthly fee and a second invoice for the extra services that were consumed. What payment methods to use? The choosen now is by bank account, and mobile phone validation with a SMS. If user doesn't pay we call that phone and ask for payment. Any examples on billing online services will be welcome! Thanks!

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  • Tips &amp; Tricks: How to crawl a SSL enabled Oracle E-Business Suite

    - by Rajesh Ghosh
    Oracle E-Business Suite can be integrated with Oracle Secure Enterprise Search for a superior end user experience and enhanced data retrieval capabilities. Before end-users can perform search operations, data has to be crawled and indexed into Oracle SES server. However if the Oracle E-Business Suite instance is on SSL, some additional configurations are needed in Oracle SES server as well as in Oracle Search Modeler, before a search object can be deployed and crawled. The process involves the following steps: Step 1: Export the SSL certificate of Oracle E-Business Suite Access the Oracle E-business Suite instance from a web browser. You should be able to locate a security or certificate icon somewhere in the browser toolbar or status bar, depending on which browser you are using. Click on it and you should be able to view the certificate as well as export it to a local file. While exporting make sure that you use “DER encoded” format. Step 2: Import the SSL certificate into Oracle Secure Enterprise server’s java key-store Oracle SES (10.1.8.4) by default ships a JDK under $ORACLE_HOME. The Oracle SES mid-tier uses this jdk to start the oc4j container services. In this step the Oracle E-Business Suite’s SSL certificate which has been exported in step #1, has to be imported into the Oracle SES server’s java key store. Perform the following: Copy the certificate file onto the server where Oracle SES server is running; under $ORACLE_HOME/jdk/jre/lib/security/cacerts. “ORACLE_HOME” points to the Oracle SES oracle home. Set the JAVA_HOME environment variable to $ORACLE_HOME/jdk. Append $JAVA_HOME/bin to the PATH environment variable Issue the command :  “keytool -import -keystore keystore.jks -trustcacerts -alias myOHS –file ebs.crt” . Please substitute “ebs.crt” with the name of the certificate file you copied in step #2.1. The default key-store password “changeit”. Enter the same when prompted. If successful this process will end with a message saying “certificate successfully imported”. Step 3: Import the SSL certificate into Search Modeler java key-store Unlike Oracle SES, Search Modeler is not shipped with a bundled JDK. If you are using standalone OC4J, then you actually use an external JDK to start the oc4j container services. If you are using IAS instance then the JDK comes bundled with the IAS installation. Perform the following: Copy the certificate file onto the server where Search Modeler application is running; under $JDK_HOME/jre/lib/security/cacerts. “JDK_HOME” points to the JDK directory depending on whether you are using external JDK or a bundled one. Set the JAVA_HOME environment variable to JDK directory. Append $JAVA_HOME/bin to the PATH environment variable Issue the command :  “keytool -import -keystore keystore.jks -trustcacerts -alias myOHS –file ebs.crt” . Please substitute “ebs.crt” with the name of the certificate file you copied in step #3.1. The default key-store password “changeit”. Enter the same when prompted. If successful this process will end with a message saying “certificate successfully imported”. Once you have completed the above steps successfully, you can deploy the search objects using Search Modeler and then start crawling them as well.

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  • Why does SEO based code tips not appear to affect ranking?

    - by Ben
    I've been researching various methods for SEO where pages have precise titles, keywords are highlighted with h tags and tick the many boxes stated in good page mark up for SEO. However when looking at some top ranked search sites on google for key terms they have terrible SEO based mark up. Really long page titles, no tags, limited appearance of keywords in the text and so on. SEO analysis services rate them lower than other sites, yet these sites rank really high. Even with a low number of back-links they are high, so I don't understand how these sites earn the position when they appear inferior to those below them which have better mark up and links. I don't want to cause trouble my mentioning sites or keywords etc. but looking in google at 'executive search' the roughly 5th placed site makes no sense why it should be highly rank, especially with all the added .swfs. The same applies for the top of 'Japan Executive Search'. My main point is that these sites seem to not have all the important structural rules stated in seo page rating applications and general suggested best practice, nor do they show large back-links. It makes me feel like there is no point bothering to write decent mark up if it really doesn't matter. Can anyone explain how sites with such mark-up, and low back-links can outrank well written and structured sites with greater linkage? Sorry if this is a fuzzy question, I want to avoid singling out any sites for example, but it really has me perplexed that sites which appear to ignore the suggested best practices rank so well.

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  • Steam (via Wine) crashes after login - any troubleshooting tips?

    - by new Thrall
    The Steam client crashes after I login. After submitting my credentials, Steam displays a dialog box informing me the client is 'connecting'. I then see the Steam main page and news page displayed for roughly a second or so before the client crashes. I'm running Ubuntu 10.10 (I think..what's the best way to verify? uname only displays Linux) which I've installed on a usb flash drive using a capser-rw file for persistence. wine-1.3.14 I'm not sure how to troubleshoot. How do I identify if the problem is with wine or steam or the video card driver, or what? Any ideas? hardware: motherboard: ECS Elitegroup 945GCT-M sound: integrated audio video: ATI Radeon X1950 console output: ubuntu@ubuntu:~/.wine/drive_c/Program Files/Steam$ wine Steam.exe fixme:process:GetLogicalProcessorInformation ((nil),0x32e488): stub fixme:process:GetLogicalProcessorInformation (0x1010c00,0x32e488): stub fixme:process:SetProcessShutdownParameters (00000100, 00000000): partial stub. fixme:urlmon:CoInternetSetFeatureEnabled 5, 0x00000002, 1, stub fixme:urlmon:CoInternetSetFeatureEnabled 10, 0x00000002, 1, stub fixme:dwmapi:DwmSetWindowAttribute (0x1009a, 2, 0x32d334, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x1009a, 3, 0x32d338, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x1009a, 4, 0x32d33c, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100a2, 2, 0x32d964, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100a2, 3, 0x32d968, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100a2, 4, 0x32d96c, 4) stub err:ole:CoGetClassObject class {77f10cf0-3db5-4966-b520-b7c54fd35ed6} not registered err:ole:CoGetClassObject no class object {77f10cf0-3db5-4966-b520-b7c54fd35ed6} could be created for context 0x1 fixme:wbemprox:wbem_locator_ConnectServer 0x1ab5f0, L"ROOT\CIMV2", (null), (null), (null), 0x00000080, (null), (nil), 0x42bbee8) fixme:dwmapi:DwmSetWindowAttribute (0x100ae, 2, 0x32d8cc, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100ae, 3, 0x32d8d0, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100ae, 4, 0x32d8d4, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100b6, 2, 0x32d80c, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100b6, 3, 0x32d810, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100b6, 4, 0x32d814, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100c0, 2, 0x32d2e4, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100c0, 3, 0x32d2e8, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100c0, 4, 0x32d2ec, 4) stub fixme:winhttp:WinHttpGetIEProxyConfigForCurrentUser returning no proxy used fixme:dwmapi:DwmSetWindowAttribute (0x100dc, 2, 0x32d94c, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100dc, 3, 0x32d950, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x100dc, 4, 0x32d954, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x10118, 2, 0x32da8c, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x10118, 3, 0x32da90, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x10118, 4, 0x32da94, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x10122, 2, 0x32d514, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x10122, 3, 0x32d518, 4) stub fixme:dwmapi:DwmSetWindowAttribute (0x10122, 4, 0x32d51c, 4) stub fixme:dbghelp:elf_search_auxv can't find symbol in module

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