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• Can JQuery/JavaScript be used to write a substantial client side application?

  - by Ian

  I have an unusual situation - I have an embedded video streaming device with a complicated UI, and I need to use an embedded web server to reproduce that UI through a web browser. I'm thinking of using JavaScript/JQuery on a C++ backend (I am NOT coding all this myself, I need to hire people for the grunt work). The embedded web server is much less powerful than a PC, so I want to write an application that runs the entire UI in the browser, and only communicates with the server to pass new program settings back and forth, get status updates from the device, and control video playback. In other words, the client gets one big page or a small number of big pages (effectively downloading the application), the application maintains significant local memory storage, and once the pages are first loaded the server never sends anything layout-related. The application has two rows of tabs to navigate ~40 menu pages, drag-and-select controls to pick cells in a grid, sorted lists, lots of standard data entry options, and it should be able to control up to 16 embedded video players at once (preferably VLC). Is this possible in JavaScript/JQuery with a C++ backend?

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• Java: Can't implement runnable on a test case: void run() collides

  - by Zombies

  So I have a test case that I want to make into a thread. I cannot extend Thread nor can I implement runnable since TestCase already has a method void run(). The compilation error I am getting is Error(62,17): method run() in class com.util.SeleneseTestCase cannot override method run() in class junit.framework.TestCase with different return type, was class junit.framework.TestResult. What I am trying to do is to scale a Selenium testcase up to perform stress testing. I am not able to use selenium grid/pushtotest.com/amazon cloud at this time (installation issues/install time/resource issues). So this really is more of a Java language issue for me.

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• Getting Data Specific to Logged in user

  - by user1770470

  I need to list logged in users active leads,and allow paging and selectable sorting, I cant use the grid because of the layout requirement. I have been searching the web for the last 2 days and cant find any viable solution Any help or direction would be greatly appreciated. var query = db.Query("SELECT a.listingId, a.datetime, c.details, c.buycommercial, c.buyindustrial, c.buyretail, c.buyland, c.tencommercial, c.tenindustrial, c.tenretail, c.tenland, c.investor, c.developer, d.companyname, d.firstname, d.lastname, d.tel, d.cell, d.email FROM dbo.tblactivebroker a JOIN dbo.tblActiveListing b ON a.ListingId = b.ListingId JOIN dbo.tblListings c ON b.ListingId = c.ListingId JOIN dbo.tblContact d ON c.crmid = d.id WHERE b.active = 'True' AND a.ActiveBrokerID = @0",brokerid);

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• Steps to take for figuring out the delay when calling service and loading data with the result?

  - by VoodooChild

  Hello, In a client server app, where client front end is done in silverlight using C# and the services are the WCF services. If I am to hit the service and do a query and bring back a result and I notice that it is taking a relatively long time to load my page which is just loading the grid with the data, what things should I look at fix this issue or how would I fix this issue? What steps could I take to determine the problem? where is the bottle-neck, can anyone know from the little information provided here? Does this have anything to do with serialization? Any insight on what could be causing this delay? My service calls are made async. I hope this question makes sense :) Thanks

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• get look up a string given a func<T,object> param

  - by Sammy

  given this code namespace GridTests { public class Grid<T> { IEnumerable<T> DataSource { get; set; } IList<Column> Columns = new List<Column>(); class Column { public string DisplayText { get; set; } Func<T, object> Rowdata { get; set; } } } } I need to be able to loop through the columns collection and get the Rowdata's object value using the DisplayText. Thanks

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• Silverlight 4 Binding to ConverterParameter

  - by FrEEzE2046

  Hello everybody, I have a ValueConverter which needs to be called with a dynamic parameter, depending on a property. I can't see a way to do this ... Width="{Binding ActualWidthValue, Source={StaticResource VisibleSize}, Converter={StaticResource Fraction}}" The "Fraction" converter get's (or should get) a parameter of type System.Size, which contains a numerator and denumerator. This value (should) depend on a ItemCollection.Count. Resetting the ItemCollection should reinvoke the Converter with the new values. My first idea was to manually change the ConverterParameter in CodeBehind on the PropertyChanged event of my ItemCollection DependencyProperty. But, as I know now, Silverlight has no GetBinding() method. I heard about GetBindingExpression and tried to do. But MyGrid.GetBindingExpression(Grid.ActualHeightProperty) is always returning null, although the Binding is already established. So, what can I do to reach my target?

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• C# How to Identify Caller for Template Events

  - by mikeknoop

  I have a ListBox container data bound and templatized as so: <ListBox x:Name="ListBox" ItemsSource="{Binding Source={StaticResource List}}" ItemTemplate="{StaticResource ListTemplate}"> </ListBox> Within my ListTemplate resource, I define a Grid which contains a few child elements. I have setup a click event handler on one of child elements. The event hander is not row-specific, and I need a (best practice) way of identifying which row in the ListBox the event fired upon. From my data source, I have an unique ID which corresponds to the row. I do not currently expose this ID in the data binding, though could. Ideally I would like the event handler to be able to identify the ID of the row the event was fired upon. Thank you!

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• UI updates not happening in the expected order

  - by allonym

  I have a Panel which hosts a number of child controls in a grid layout. The child controls each consist of a Panel with a PictureBox and a Label. When one of these child controls is clicked it becomes "selected" (which basically entails changing its background to a different color) and an event is fired. In the handler for this event, an image is displayed in a PictureBox on a separate form. In code, the background of the child control is definitely changed before firing the event, but for some reason it never updates at runtime until after the image has updated in the other Form. I've tried to Invalidate() and Refresh() the child control before firing the event, without effect. Why is this happening, and what can I do to set it right?

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• join query with lowstock products with another table in magento

  - by muralikalpana

  I want to display some attributes in reports/products/lowstock grid. here how can i join another table with lowstock product id? here is the query /** @var $collection Mage_Reports_Model_Resource_Product_Lowstock_Collection */ $collection = Mage::getResourceModel('reports/product_lowstock_collection') ->addAttributeToSelect('*') ->setStoreId($storeId) ->filterByIsQtyProductTypes() ->joinInventoryItem('qty') ->joinInventoryItem('low_stock_date') ->useManageStockFilter($storeId) ->useNotifyStockQtyFilter($storeId) ->setOrder('qty', Varien_Data_Collection::SORT_ORDER_ASC); here i have to join with this productid with another table. i am not getting results if i use this query. $collection->getSelect()->join(array('t2' => 'lowstockorders'),'lowstock_inventory_item.product_id = t2.product_id','t2.product_id'); please anybody tell me how to join these tables thanks, murali

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• .net: How do you feed a winform after clicking on a row of a datagridview of search form?

  - by odiseh

  I have a winform which is responsible for doing a search by some conditions that users enters and then selects the records from a Database. The search form has a data grid view which shows the result. After searching, user clikcs on a row of the datagridview and then another form (for example frmShowDetails) will be displayed. My question is when displaying frmShowDetails, what are your suggestions to send the id of selected row to frmShowDetails in order to feed it to show data in .net? Do you use form property or a private mariable which sets by only form constructor? Thank you

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• In Cocoa (or maybe GUI development in general) how do you specify an arbitrary number of things tile

  - by RankWeis

  I'm new to creating GUI's, everything I've done up until this point is using the command line. I'm trying to create a port of minesweeper to the macintosh, as an experiment, and I've got the CLI working, but I'm running into walls everywhere with the gui. The first thing it seems I have to do, however, is be able to tile n x m 'boxes' for grid - and I'm not sure how to do that. The information is ready to be handed to it, but I don't know where to do it, or how. Also, if anyone has any recommendations for sites/Cocoa development books, feel free to drop them in here... Thanks!

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• How do I create if statements in php to perform a specific action depending on what form has string in it

  - by user1637284

  Im trying to create a grid on my page in each cell there will be a simple one line form. If a person enters data into lets say FieldA I would like the php to perform actionA but if the data was entered in FieldF I would like actionF performed. Is this possible without having to create a php for each cell and upload all those php files? Or is there a way to perform the GET method in each form to append the data to the end of the action url without the field name showing (ie sample.com/somestuff/fieldA instead of sample.com/somestuff/fieldname=fieldA) thus not needing php at all?

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• How to identify each parameter type in a C# method?

  - by user465876

  I have a C# method say: MyMethod(int num, string name, Color color, MyComplexType complex) Using reflection, how can I distinctly identify each of the parameter types of any method? I want to perform some task by parameter type. If the type is simple int, string or boolean then I do something, if it is Color, XMLDocument, etc I do something else and if it is user defined type like MyComplexType or MyCalci etc then I want to do certain task. I am able to retrieve all the parameters of a method using ParameterInfo and can loop through each parameter and get their types. But how can I identify each data type? foreach (var parameter in parameters) { //identify primitive types?? //identify value types //identify reference types } Edit: this is apart of my code to create a propert grid sort of page where I want to show the parameter list with data types for the selected method. If the parameter has any userdefined type/reference type then I want to expand it further to show all the elements under it with datatypes.

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• asp.net c# ToolTip with image inside of it

  - by Web Dev

  I currently have a hyperlink control as such: I am setting the logo text of it as such within my grid: HyperLink logoLink = (HyperLink)e.Item.FindControl("logoLink"); logoLink.Text = lblsub + ".gif"; What I like to do is that when a user clicks on the hyperlink, I like the gif file to show witin a tooltip. what is the easiest way of doint this? The image is in the Image folder so the path would be as such: Images/ + lblsub + ".gif"; Note that I am using ASP.NET C#. Thanks in advance

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• Why do we need to estimate the true position in Kalman filters?

  - by Kalla

  I am following a probably well-known tutorial about Kalman filter here From these lines of code: figure; plot(t,pos, t,posmeas, t,poshat); grid; xlabel('Time (sec)'); ylabel('Position (feet)'); title('Figure 1 - Vehicle Position (True, Measured, and Estimated)') I understand that x is the true position, y is measured position, xhat is estimated position. Then, if we can compute x (this code: x = a * x + b * u + ProcessNoise;), why do we need to estimated x anymore?

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• New features of C# 4.0

  This article covers New features of C# 4.0. Article has been divided into below sections. Introduction. Dynamic Lookup. Named and Optional Arguments. Features for COM interop. Variance. Relationship with Visual Basic. Resources. Other interested readings… 22 New Features of Visual Studio 2008 for .NET Professionals 50 New Features of SQL Server 2008 IIS 7.0 New features Introduction It is now close to a year since Microsoft Visual C# 3.0 shipped as part of Visual Studio 2008. In the VS Managed Languages team we are hard at work on creating the next version of the language (with the unsurprising working title of C# 4.0), and this document is a first public description of the planned language features as we currently see them. Please be advised that all this is in early stages of production and is subject to change. Part of the reason for sharing our plans in public so early is precisely to get the kind of feedback that will cause us to improve the final product before it rolls out. Simultaneously with the publication of this whitepaper, a first public CTP (community technology preview) of Visual Studio 2010 is going out as a Virtual PC image for everyone to try. Please use it to play and experiment with the features, and let us know of any thoughts you have. We ask for your understanding and patience working with very early bits, where especially new or newly implemented features do not have the quality or stability of a final product. The aim of the CTP is not to give you a productive work environment but to give you the best possible impression of what we are working on for the next release. The CTP contains a number of walkthroughs, some of which highlight the new language features of C# 4.0. Those are excellent for getting a hands-on guided tour through the details of some common scenarios for the features. You may consider this whitepaper a companion document to these walkthroughs, complementing them with a focus on the overall language features and how they work, as opposed to the specifics of the concrete scenarios. C# 4.0 The major theme for C# 4.0 is dynamic programming. Increasingly, objects are “dynamic” in the sense that their structure and behavior is not captured by a static type, or at least not one that the compiler knows about when compiling your program. Some examples include a. objects from dynamic programming languages, such as Python or Ruby b. COM objects accessed through IDispatch c. ordinary .NET types accessed through reflection d. objects with changing structure, such as HTML DOM objects While C# remains a statically typed language, we aim to vastly improve the interaction with such objects. A secondary theme is co-evolution with Visual Basic. Going forward we will aim to maintain the individual character of each language, but at the same time important new features should be introduced in both languages at the same time. They should be differentiated more by style and feel than by feature set. The new features in C# 4.0 fall into four groups: Dynamic lookup Dynamic lookup allows you to write method, operator and indexer calls, property and field accesses, and even object invocations which bypass the C# static type checking and instead gets resolved at runtime. Named and optional parameters Parameters in C# can now be specified as optional by providing a default value for them in a member declaration. When the member is invoked, optional arguments can be omitted. Furthermore, any argument can be passed by parameter name instead of position. COM specific interop features Dynamic lookup as well as named and optional parameters both help making programming against COM less painful than today. On top of that, however, we are adding a number of other small features that further improve the interop experience. Variance It used to be that an IEnumerable<string> wasn’t an IEnumerable<object>. Now it is – C# embraces type safe “co-and contravariance” and common BCL types are updated to take advantage of that. Dynamic Lookup Dynamic lookup allows you a unified approach to invoking things dynamically. With dynamic lookup, when you have an object in your hand you do not need to worry about whether it comes from COM, IronPython, the HTML DOM or reflection; you just apply operations to it and leave it to the runtime to figure out what exactly those operations mean for that particular object. This affords you enormous flexibility, and can greatly simplify your code, but it does come with a significant drawback: Static typing is not maintained for these operations. A dynamic object is assumed at compile time to support any operation, and only at runtime will you get an error if it wasn’t so. Oftentimes this will be no loss, because the object wouldn’t have a static type anyway, in other cases it is a tradeoff between brevity and safety. In order to facilitate this tradeoff, it is a design goal of C# to allow you to opt in or opt out of dynamic behavior on every single call. The dynamic type C# 4.0 introduces a new static type called dynamic. When you have an object of type dynamic you can “do things to it” that are resolved only at runtime: dynamic d = GetDynamicObject(…); d.M(7); The C# compiler allows you to call a method with any name and any arguments on d because it is of type dynamic. At runtime the actual object that d refers to will be examined to determine what it means to “call M with an int” on it. The type dynamic can be thought of as a special version of the type object, which signals that the object can be used dynamically. It is easy to opt in or out of dynamic behavior: any object can be implicitly converted to dynamic, “suspending belief” until runtime. Conversely, there is an “assignment conversion” from dynamic to any other type, which allows implicit conversion in assignment-like constructs: dynamic d = 7; // implicit conversion int i = d; // assignment conversion Dynamic operations Not only method calls, but also field and property accesses, indexer and operator calls and even delegate invocations can be dispatched dynamically: dynamic d = GetDynamicObject(…); d.M(7); // calling methods d.f = d.P; // getting and settings fields and properties d[“one”] = d[“two”]; // getting and setting thorugh indexers int i = d + 3; // calling operators string s = d(5,7); // invoking as a delegate The role of the C# compiler here is simply to package up the necessary information about “what is being done to d”, so that the runtime can pick it up and determine what the exact meaning of it is given an actual object d. Think of it as deferring part of the compiler’s job to runtime. The result of any dynamic operation is itself of type dynamic. Runtime lookup At runtime a dynamic operation is dispatched according to the nature of its target object d: COM objects If d is a COM object, the operation is dispatched dynamically through COM IDispatch. This allows calling to COM types that don’t have a Primary Interop Assembly (PIA), and relying on COM features that don’t have a counterpart in C#, such as indexed properties and default properties. Dynamic objects If d implements the interface IDynamicObject d itself is asked to perform the operation. Thus by implementing IDynamicObject a type can completely redefine the meaning of dynamic operations. This is used intensively by dynamic languages such as IronPython and IronRuby to implement their own dynamic object models. It will also be used by APIs, e.g. by the HTML DOM to allow direct access to the object’s properties using property syntax. Plain objects Otherwise d is a standard .NET object, and the operation will be dispatched using reflection on its type and a C# “runtime binder” which implements C#’s lookup and overload resolution semantics at runtime. This is essentially a part of the C# compiler running as a runtime component to “finish the work” on dynamic operations that was deferred by the static compiler. Example Assume the following code: dynamic d1 = new Foo(); dynamic d2 = new Bar(); string s; d1.M(s, d2, 3, null); Because the receiver of the call to M is dynamic, the C# compiler does not try to resolve the meaning of the call. Instead it stashes away information for the runtime about the call. This information (often referred to as the “payload”) is essentially equivalent to: “Perform an instance method call of M with the following arguments: 1. a string 2. a dynamic 3. a literal int 3 4. a literal object null” At runtime, assume that the actual type Foo of d1 is not a COM type and does not implement IDynamicObject. In this case the C# runtime binder picks up to finish the overload resolution job based on runtime type information, proceeding as follows: 1. Reflection is used to obtain the actual runtime types of the two objects, d1 and d2, that did not have a static type (or rather had the static type dynamic). The result is Foo for d1 and Bar for d2. 2. Method lookup and overload resolution is performed on the type Foo with the call M(string,Bar,3,null) using ordinary C# semantics. 3. If the method is found it is invoked; otherwise a runtime exception is thrown. Overload resolution with dynamic arguments Even if the receiver of a method call is of a static type, overload resolution can still happen at runtime. This can happen if one or more of the arguments have the type dynamic: Foo foo = new Foo(); dynamic d = new Bar(); var result = foo.M(d); The C# runtime binder will choose between the statically known overloads of M on Foo, based on the runtime type of d, namely Bar. The result is again of type dynamic. The Dynamic Language Runtime An important component in the underlying implementation of dynamic lookup is the Dynamic Language Runtime (DLR), which is a new API in .NET 4.0. The DLR provides most of the infrastructure behind not only C# dynamic lookup but also the implementation of several dynamic programming languages on .NET, such as IronPython and IronRuby. Through this common infrastructure a high degree of interoperability is ensured, but just as importantly the DLR provides excellent caching mechanisms which serve to greatly enhance the efficiency of runtime dispatch. To the user of dynamic lookup in C#, the DLR is invisible except for the improved efficiency. However, if you want to implement your own dynamically dispatched objects, the IDynamicObject interface allows you to interoperate with the DLR and plug in your own behavior. This is a rather advanced task, which requires you to understand a good deal more about the inner workings of the DLR. For API writers, however, it can definitely be worth the trouble in order to vastly improve the usability of e.g. a library representing an inherently dynamic domain. Open issues There are a few limitations and things that might work differently than you would expect. · The DLR allows objects to be created from objects that represent classes. However, the current implementation of C# doesn’t have syntax to support this. · Dynamic lookup will not be able to find extension methods. Whether extension methods apply or not depends on the static context of the call (i.e. which using clauses occur), and this context information is not currently kept as part of the payload. · Anonymous functions (i.e. lambda expressions) cannot appear as arguments to a dynamic method call. The compiler cannot bind (i.e. “understand”) an anonymous function without knowing what type it is converted to. One consequence of these limitations is that you cannot easily use LINQ queries over dynamic objects: dynamic collection = …; var result = collection.Select(e => e + 5); If the Select method is an extension method, dynamic lookup will not find it. Even if it is an instance method, the above does not compile, because a lambda expression cannot be passed as an argument to a dynamic operation. There are no plans to address these limitations in C# 4.0. Named and Optional Arguments Named and optional parameters are really two distinct features, but are often useful together. Optional parameters allow you to omit arguments to member invocations, whereas named arguments is a way to provide an argument using the name of the corresponding parameter instead of relying on its position in the parameter list. Some APIs, most notably COM interfaces such as the Office automation APIs, are written specifically with named and optional parameters in mind. Up until now it has been very painful to call into these APIs from C#, with sometimes as many as thirty arguments having to be explicitly passed, most of which have reasonable default values and could be omitted. Even in APIs for .NET however you sometimes find yourself compelled to write many overloads of a method with different combinations of parameters, in order to provide maximum usability to the callers. Optional parameters are a useful alternative for these situations. Optional parameters A parameter is declared optional simply by providing a default value for it: public void M(int x, int y = 5, int z = 7); Here y and z are optional parameters and can be omitted in calls: M(1, 2, 3); // ordinary call of M M(1, 2); // omitting z – equivalent to M(1, 2, 7) M(1); // omitting both y and z – equivalent to M(1, 5, 7) Named and optional arguments C# 4.0 does not permit you to omit arguments between commas as in M(1,,3). This could lead to highly unreadable comma-counting code. Instead any argument can be passed by name. Thus if you want to omit only y from a call of M you can write: M(1, z: 3); // passing z by name or M(x: 1, z: 3); // passing both x and z by name or even M(z: 3, x: 1); // reversing the order of arguments All forms are equivalent, except that arguments are always evaluated in the order they appear, so in the last example the 3 is evaluated before the 1. Optional and named arguments can be used not only with methods but also with indexers and constructors. Overload resolution Named and optional arguments affect overload resolution, but the changes are relatively simple: A signature is applicable if all its parameters are either optional or have exactly one corresponding argument (by name or position) in the call which is convertible to the parameter type. Betterness rules on conversions are only applied for arguments that are explicitly given – omitted optional arguments are ignored for betterness purposes. If two signatures are equally good, one that does not omit optional parameters is preferred. M(string s, int i = 1); M(object o); M(int i, string s = “Hello”); M(int i); M(5); Given these overloads, we can see the working of the rules above. M(string,int) is not applicable because 5 doesn’t convert to string. M(int,string) is applicable because its second parameter is optional, and so, obviously are M(object) and M(int). M(int,string) and M(int) are both better than M(object) because the conversion from 5 to int is better than the conversion from 5 to object. Finally M(int) is better than M(int,string) because no optional arguments are omitted. Thus the method that gets called is M(int). Features for COM interop Dynamic lookup as well as named and optional parameters greatly improve the experience of interoperating with COM APIs such as the Office Automation APIs. In order to remove even more of the speed bumps, a couple of small COM-specific features are also added to C# 4.0. Dynamic import Many COM methods accept and return variant types, which are represented in the PIAs as object. In the vast majority of cases, a programmer calling these methods already knows the static type of a returned object from context, but explicitly has to perform a cast on the returned value to make use of that knowledge. These casts are so common that they constitute a major nuisance. In order to facilitate a smoother experience, you can now choose to import these COM APIs in such a way that variants are instead represented using the type dynamic. In other words, from your point of view, COM signatures now have occurrences of dynamic instead of object in them. This means that you can easily access members directly off a returned object, or you can assign it to a strongly typed local variable without having to cast. To illustrate, you can now say excel.Cells[1, 1].Value = "Hello"; instead of ((Excel.Range)excel.Cells[1, 1]).Value2 = "Hello"; and Excel.Range range = excel.Cells[1, 1]; instead of Excel.Range range = (Excel.Range)excel.Cells[1, 1]; Compiling without PIAs Primary Interop Assemblies are large .NET assemblies generated from COM interfaces to facilitate strongly typed interoperability. They provide great support at design time, where your experience of the interop is as good as if the types where really defined in .NET. However, at runtime these large assemblies can easily bloat your program, and also cause versioning issues because they are distributed independently of your application. The no-PIA feature allows you to continue to use PIAs at design time without having them around at runtime. Instead, the C# compiler will bake the small part of the PIA that a program actually uses directly into its assembly. At runtime the PIA does not have to be loaded. Omitting ref Because of a different programming model, many COM APIs contain a lot of reference parameters. Contrary to refs in C#, these are typically not meant to mutate a passed-in argument for the subsequent benefit of the caller, but are simply another way of passing value parameters. It therefore seems unreasonable that a C# programmer should have to create temporary variables for all such ref parameters and pass these by reference. Instead, specifically for COM methods, the C# compiler will allow you to pass arguments by value to such a method, and will automatically generate temporary variables to hold the passed-in values, subsequently discarding these when the call returns. In this way the caller sees value semantics, and will not experience any side effects, but the called method still gets a reference. Open issues A few COM interface features still are not surfaced in C#. Most notably these include indexed properties and default properties. As mentioned above these will be respected if you access COM dynamically, but statically typed C# code will still not recognize them. There are currently no plans to address these remaining speed bumps in C# 4.0. Variance An aspect of generics that often comes across as surprising is that the following is illegal: IList<string> strings = new List<string>(); IList<object> objects = strings; The second assignment is disallowed because strings does not have the same element type as objects. There is a perfectly good reason for this. If it were allowed you could write: objects[0] = 5; string s = strings[0]; Allowing an int to be inserted into a list of strings and subsequently extracted as a string. This would be a breach of type safety. However, there are certain interfaces where the above cannot occur, notably where there is no way to insert an object into the collection. Such an interface is IEnumerable<T>. If instead you say: IEnumerable<object> objects = strings; There is no way we can put the wrong kind of thing into strings through objects, because objects doesn’t have a method that takes an element in. Variance is about allowing assignments such as this in cases where it is safe. The result is that a lot of situations that were previously surprising now just work. Covariance In .NET 4.0 the IEnumerable<T> interface will be declared in the following way: public interface IEnumerable<out T> : IEnumerable { IEnumerator<T> GetEnumerator(); } public interface IEnumerator<out T> : IEnumerator { bool MoveNext(); T Current { get; } } The “out” in these declarations signifies that the T can only occur in output position in the interface – the compiler will complain otherwise. In return for this restriction, the interface becomes “covariant” in T, which means that an IEnumerable<A> is considered an IEnumerable<B> if A has a reference conversion to B. As a result, any sequence of strings is also e.g. a sequence of objects. This is useful e.g. in many LINQ methods. Using the declarations above: var result = strings.Union(objects); // succeeds with an IEnumerable<object> This would previously have been disallowed, and you would have had to to some cumbersome wrapping to get the two sequences to have the same element type. Contravariance Type parameters can also have an “in” modifier, restricting them to occur only in input positions. An example is IComparer<T>: public interface IComparer<in T> { public int Compare(T left, T right); } The somewhat baffling result is that an IComparer<object> can in fact be considered an IComparer<string>! It makes sense when you think about it: If a comparer can compare any two objects, it can certainly also compare two strings. This property is referred to as contravariance. A generic type can have both in and out modifiers on its type parameters, as is the case with the Func<…> delegate types: public delegate TResult Func<in TArg, out TResult>(TArg arg); Obviously the argument only ever comes in, and the result only ever comes out. Therefore a Func<object,string> can in fact be used as a Func<string,object>. Limitations Variant type parameters can only be declared on interfaces and delegate types, due to a restriction in the CLR. Variance only applies when there is a reference conversion between the type arguments. For instance, an IEnumerable<int> is not an IEnumerable<object> because the conversion from int to object is a boxing conversion, not a reference conversion. Also please note that the CTP does not contain the new versions of the .NET types mentioned above. In order to experiment with variance you have to declare your own variant interfaces and delegate types. COM Example Here is a larger Office automation example that shows many of the new C# features in action. using System; using System.Diagnostics; using System.Linq; using Excel = Microsoft.Office.Interop.Excel; using Word = Microsoft.Office.Interop.Word; class Program { static void Main(string[] args) { var excel = new Excel.Application(); excel.Visible = true; excel.Workbooks.Add(); // optional arguments omitted excel.Cells[1, 1].Value = "Process Name"; // no casts; Value dynamically excel.Cells[1, 2].Value = "Memory Usage"; // accessed var processes = Process.GetProcesses() .OrderByDescending(p =&gt; p.WorkingSet) .Take(10); int i = 2; foreach (var p in processes) { excel.Cells[i, 1].Value = p.ProcessName; // no casts excel.Cells[i, 2].Value = p.WorkingSet; // no casts i++; } Excel.Range range = excel.Cells[1, 1]; // no casts Excel.Chart chart = excel.ActiveWorkbook.Charts. Add(After: excel.ActiveSheet); // named and optional arguments chart.ChartWizard( Source: range.CurrentRegion, Title: "Memory Usage in " + Environment.MachineName); //named+optional chart.ChartStyle = 45; chart.CopyPicture(Excel.XlPictureAppearance.xlScreen, Excel.XlCopyPictureFormat.xlBitmap, Excel.XlPictureAppearance.xlScreen); var word = new Word.Application(); word.Visible = true; word.Documents.Add(); // optional arguments word.Selection.Paste(); } } The code is much more terse and readable than the C# 3.0 counterpart. Note especially how the Value property is accessed dynamically. This is actually an indexed property, i.e. a property that takes an argument; something which C# does not understand. However the argument is optional. Since the access is dynamic, it goes through the runtime COM binder which knows to substitute the default value and call the indexed property. Thus, dynamic COM allows you to avoid accesses to the puzzling Value2 property of Excel ranges. Relationship with Visual Basic A number of the features introduced to C# 4.0 already exist or will be introduced in some form or other in Visual Basic: · Late binding in VB is similar in many ways to dynamic lookup in C#, and can be expected to make more use of the DLR in the future, leading to further parity with C#. · Named and optional arguments have been part of Visual Basic for a long time, and the C# version of the feature is explicitly engineered with maximal VB interoperability in mind. · NoPIA and variance are both being introduced to VB and C# at the same time. VB in turn is adding a number of features that have hitherto been a mainstay of C#. As a result future versions of C# and VB will have much better feature parity, for the benefit of everyone. Resources All available resources concerning C# 4.0 can be accessed through the C# Dev Center. Specifically, this white paper and other resources can be found at the Code Gallery site. Enjoy! span.fullpost {display:none;}

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• Integrating HTML into Silverlight Applications

  - by dwahlin

  Looking for a way to display HTML content within a Silverlight application? If you haven’t tried doing that before it can be challenging at first until you know a few tricks of the trade.  Being able to display HTML is especially handy when you’re required to display RSS feeds (with embedded HTML), SQL Server Reporting Services reports, PDF files (not actually HTML – but the techniques discussed will work), or other HTML content.  In this post I'll discuss three options for displaying HTML content in Silverlight applications and describe how my company is using these techniques in client applications. Displaying HTML Overlays If you need to display HTML over a Silverlight application (such as an RSS feed containing HTML data in it) you’ll need to set the Silverlight control’s windowless parameter to true. This can be done using the object tag as shown next: <object data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="100%" height="100%"> <param name="source" value="ClientBin/HTMLAndSilverlight.xap"/> <param name="onError" value="onSilverlightError" /> <param name="background" value="white" /> <param name="minRuntimeVersion" value="4.0.50401.0" /> <param name="autoUpgrade" value="true" /> <param name="windowless" value="true" /> <a href="http://go.microsoft.com/fwlink/?LinkID=149156&v=4.0.50401.0" style="text-decoration:none"> <img src="http://go.microsoft.com/fwlink/?LinkId=161376" alt="Get Microsoft Silverlight" style="border-style:none"/> </a> </object> By setting the control to “windowless” you can overlay HTML objects by using absolute positioning and other CSS techniques. Keep in mind that on Windows machines the windowless setting can result in a performance hit when complex animations or HD video are running since the plug-in content is displayed directly by the browser window. It goes without saying that you should only set windowless to true when you really need the functionality it offers. For example, if I want to display my blog’s RSS content on top of a Silverlight application I could set windowless to true and create a user control that grabbed the content and output it using a DataList control: <style type="text/css"> a {text-decoration:none;font-weight:bold;font-size:14pt;} </style> <div style="margin-top:10px; margin-left:10px;margin-right:5px;"> <asp:DataList ID="RSSDataList" runat="server" DataSourceID="RSSDataSource"> <ItemTemplate> <a href='<%# XPath("link") %>'><%# XPath("title") %></a> <br /> <%# XPath("description") %> <br /> </ItemTemplate> </asp:DataList> <asp:XmlDataSource ID="RSSDataSource" DataFile="http://weblogs.asp.net/dwahlin/rss.aspx" XPath="rss/channel/item" CacheDuration="60" runat="server" /> </div> The user control can then be placed in the page hosting the Silverlight control as shown below. This example adds a Close button, additional content to display in the overlay window and the HTML generated from the user control. <div id="RSSDiv"> <div style="background-color:#484848;border:1px solid black;height:35px;width:100%;"> <img alt="Close Button" align="right" src="Images/Close.png" onclick="HideOverlay();" style="cursor:pointer;" /> </div> <div style="overflow:auto;width:800px;height:565px;"> <div style="float:left;width:100px;height:103px;margin-left:10px;margin-top:5px;"> <img src="http://weblogs.asp.net/blogs/dwahlin/dan2008.jpg" style="border:1px solid Gray" /> </div> <div style="float:left;width:300px;height:103px;margin-top:5px;"> <a href="http://weblogs.asp.net/dwahlin" style="margin-left:10px;font-size:20pt;">Dan Wahlin's Blog</a> </div> <br /><br /><br /> <div style="clear:both;margin-top:20px;"> <uc:BlogRoller ID="BlogRoller" runat="server" /> </div> </div> </div> Of course, we wouldn’t want the RSS HTML content to be shown until requested. Once it’s requested the absolute position of where it should show above the Silverlight control can be set using standard CSS styles. The following ID selector named #RSSDiv handles hiding the overlay div shown above and determines where it will be display on the screen. #RSSDiv { background-color:White; position:absolute; top:100px; left:300px; width:800px; height:600px; border:1px solid black; display:none; } Now that the HTML content to display above the Silverlight control is set, how can we show it as a user clicks a HyperlinkButton or other control in the application? Fortunately, Silverlight provides an excellent HTML bridge that allows direct access to content hosted within a page. The following code shows two JavaScript functions that can be called from Siverlight to handle showing or hiding HTML overlay content. The two functions rely on jQuery (http://www.jQuery.com) to make it easy to select HTML objects and manipulate their properties: function ShowOverlay() { rssDiv.css('display', 'block'); } function HideOverlay() { rssDiv.css('display', 'none'); } Calling the ShowOverlay function is as simple as adding the following code into the Silverlight application within a button’s Click event handler: private void OverlayHyperlinkButton_Click(object sender, RoutedEventArgs e) { HtmlPage.Window.Invoke("ShowOverlay"); } The result of setting the Silverlight control’s windowless parameter to true and showing the HTML overlay content is shown in the following screenshot:   Thinking Outside the Box to Show HTML Content Setting the windowless parameter to true may not be a viable option for some Silverlight applications or you may simply want to go about showing HTML content a different way. The next technique I’ll show takes advantage of simple HTML, CSS and JavaScript code to handle showing HTML content while a Silverlight application is running in the browser. Keep in mind that with Silverlight’s HTML bridge feature you can always pop-up HTML content in a new browser window using code similar to the following: System.Windows.Browser.HtmlPage.Window.Navigate( new Uri("http://silverlight.net"), "_blank"); For this example I’ll demonstrate how to hide the Silverlight application while maximizing a container div containing the HTML content to show. This allows HTML content to take up the full screen area of the browser without having to set windowless to true and when done right can make the user feel like they never left the Silverlight application. The following HTML shows several div elements that are used to display HTML within the same browser window as the Silverlight application: <div id="JobPlanDiv"> <div style="vertical-align:middle"> <img alt="Close Button" align="right" src="Images/Close.png" onclick="HideJobPlanIFrame();" style="cursor:pointer;" /> </div> <div id="JobPlan_IFrame_Container" style="height:95%;width:100%;margin-top:37px;"></div> </div> The JobPlanDiv element acts as a container for two other divs that handle showing a close button and hosting an iframe that will be added dynamically at runtime. JobPlanDiv isn’t visible when the Silverlight application loads due to the following ID selector added into the page: #JobPlanDiv { position:absolute; background-color:#484848; overflow:hidden; left:0; top:0; height:100%; width:100%; display:none; } When the HTML content needs to be shown or hidden the JavaScript functions shown next can be used: var jobPlanIFrameID = 'JobPlan_IFrame'; var slHost = null; var jobPlanContainer = null; var jobPlanIFrameContainer = null; var rssDiv = null; $(document).ready(function () { slHost = $('#silverlightControlHost'); jobPlanContainer = $('#JobPlanDiv'); jobPlanIFrameContainer = $('#JobPlan_IFrame_Container'); rssDiv = $('#RSSDiv'); }); function ShowJobPlanIFrame(url) { jobPlanContainer.css('display', 'block'); $('<iframe id="' + jobPlanIFrameID + '" src="' + url + '" style="height:100%;width:100%;" />') .appendTo(jobPlanIFrameContainer); slHost.css('width', '0%'); } function HideJobPlanIFrame() { jobPlanContainer.css('display', 'none'); $('#' + jobPlanIFrameID).remove(); slHost.css('width', '100%'); } ShowJobPlanIFrame() handles showing the JobPlanDiv div and adding an iframe into it dynamically. Once JobPlanDiv is shown, the Silverlight control host has its width set to a value of 0% to allow the control to stay alive while making it invisible to the user. I found that this technique works better across multiple browsers as opposed to manipulating the Silverlight control host div’s display or visibility properties. Now that you’ve seen the code to handle showing and hiding the HTML content area, let’s switch focus to the Silverlight application. As a user clicks on a link such as “View Report” the ShowJobPlanIFrame() JavaScript function needs to be called. The following code handles that task: private void ReportHyperlinkButton_Click(object sender, RoutedEventArgs e) { ShowBrowser(_BaseUrl + "/Report.aspx"); } public void ShowBrowser(string url) { HtmlPage.Window.Invoke("ShowJobPlanIFrame", url); } Any URL can be passed into the ShowBrowser() method which handles invoking the JavaScript function. This includes standard web pages or even PDF files. We’ve used this technique frequently with our SmartPrint control (http://www.smartwebcontrols.com) which converts Silverlight screens into PDF documents and displays them. Here’s an example of the content generated:   Silverlight 4’s WebBrowser Control Both techniques shown to this point work well when Silverlight is running in-browser but not so well when it’s running out-of-browser since there’s no host page that you can access using the HTML bridge. Fortunately, Silverlight 4 provides a WebBrowser control that can be used to perform the same functionality quite easily. We’re currently using it in client applications to display PDF documents, SSRS reports and standard HTML content. Using the WebBrowser control simplifies the application quite a bit since no JavaScript is required if the application only runs out-of-browser. Here’s a simple example of defining the WebBrowser control in XAML. I typically define it in MainPage.xaml when a Silverlight Navigation template is used to create the project so that I can re-use the functionality across multiple screens. <Grid x:Name="WebBrowserGrid" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Visibility="Collapsed"> <StackPanel HorizontalAlignment="Stretch" VerticalAlignment="Stretch"> <Border Background="#484848" HorizontalAlignment="Stretch" Height="40"> <Image x:Name="WebBrowserImage" Width="100" Height="33" Cursor="Hand" HorizontalAlignment="Right" Source="/HTMLAndSilverlight;component/Assets/Images/Close.png" MouseLeftButtonDown="WebBrowserImage_MouseLeftButtonDown" /> </Border> <WebBrowser x:Name="JobPlanReportWebBrowser" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" /> </StackPanel> </Grid> Looking through the XAML you can see that a close image is defined along with the WebBrowser control. Because the URL that the WebBrowser should navigate to isn’t known at design time no value is assigned to the control’s Source property. If the XAML shown above is left “as is” you’ll find that any HTML content assigned to the WebBrowser doesn’t display properly. This is due to no height or width being set on the control. To handle this issue the following code is added into the XAML’s code-behind file to dynamically determine the height and width of the page and assign it to the WebBrowser. This is done by handling the SizeChanged event. void MainPage_SizeChanged(object sender, SizeChangedEventArgs e) { WebBrowserGrid.Height = JobPlanReportWebBrowser.Height = ActualHeight; WebBrowserGrid.Width = JobPlanReportWebBrowser.Width = ActualWidth; } When the user wants to view HTML content they click a button which executes the code shown in next: public void ShowBrowser(string url) { if (Application.Current.IsRunningOutOfBrowser) { JobPlanReportWebBrowser.NavigateToString("<html><body><iframe src='" + url + "' style='width:100%;height:97%;' /></body></html>"); WebBrowserGrid.Visibility = Visibility.Visible; } else { HtmlPage.Window.Invoke("ShowJobPlanIFrame", url); } } private void WebBrowserImage_MouseLeftButtonDown(object sender, MouseButtonEventArgs e) { WebBrowserGrid.Visibility = Visibility.Collapsed; }   Looking through the code you’ll see that it checks to see if the Silverlight application is running out-of-browser and then either displays the WebBrowser control or runs the JavaScript function discussed earlier. Although the WebBrowser control’s Source property could be assigned the URI of the page to navigate to, by assigning HTML content using the NavigateToString() method and adding an iframe, content can be shown from any site including cross-domain sites. This is especially handy when you need to grab a page from a reporting site that’s in a different domain than the Silverlight application. Here’s an example of viewing  PDF file inside of an out-of-browser application. The first image shows the application running out-of-browser before the user clicks a PDF HyperlinkButton.  The second image shows the PDF being displayed.   While there are certainly other techniques that can be used, the ones shown here have worked well for us in different applications and provide the ability to display HTML content in-browser or out-of-browser. Feel free to add a comment if you have another tip or trick you like to use when working with HTML content in Silverlight applications.   Download Code Sample   For more information about onsite, online and video training, mentoring and consulting solutions for .NET, SharePoint or Silverlight please visit http://www.thewahlingroup.com.

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• Introducing the Earthquake Locator – A Bing Maps Silverlight Application, part 1

  - by Bobby Diaz

  Update: Live demo and source code now available!  The recent wave of earthquakes (no pun intended) being reported in the news got me wondering about the frequency and severity of earthquakes around the world. Since I’ve been doing a lot of Silverlight development lately, I decided to scratch my curiosity with a nice little Bing Maps application that will show the location and relative strength of recent seismic activity. Here is a list of technologies this application will utilize, so be sure to have everything downloaded and installed if you plan on following along. Silverlight 3 WCF RIA Services Bing Maps Silverlight Control * Managed Extensibility Framework (optional) MVVM Light Toolkit (optional) log4net (optional) * If you are new to Bing Maps or have not signed up for a Developer Account, you will need to visit www.bingmapsportal.com to request a Bing Maps key for your application. Getting Started We start out by creating a new Silverlight Application called EarthquakeLocator and specify that we want to automatically create the Web Application Project with RIA Services enabled. I cleaned up the web app by removing the Default.aspx and EarthquakeLocatorTestPage.html. Then I renamed the EarthquakeLocatorTestPage.aspx to Default.aspx and set it as my start page. I also set the development server to use a specific port, as shown below. RIA Services Next, I created a Services folder in the EarthquakeLocator.Web project and added a new Domain Service Class called EarthquakeService.cs. This is the RIA Services Domain Service that will provide earthquake data for our client application. I am not using LINQ to SQL or Entity Framework, so I will use the <empty domain service class> option. We will be pulling data from an external Atom feed, but this example could just as easily pull data from a database or another web service. This is an important distinction to point out because each scenario I just mentioned could potentially use a different Domain Service base class (i.e. LinqToSqlDomainService<TDataContext>). Now we can start adding Query methods to our EarthquakeService that pull data from the USGS web site. Here is the complete code for our service class: using System; using System.Collections.Generic; using System.IO; using System.Linq; using System.ServiceModel.Syndication; using System.Web.DomainServices; using System.Web.Ria; using System.Xml; using log4net; using EarthquakeLocator.Web.Model;   namespace EarthquakeLocator.Web.Services {     /// <summary>     /// Provides earthquake data to client applications.     /// </summary>     [EnableClientAccess()]     public class EarthquakeService : DomainService     {         private static readonly ILog log = LogManager.GetLogger(typeof(EarthquakeService));           // USGS Data Feeds: http://earthquake.usgs.gov/earthquakes/catalogs/         private const string FeedForPreviousDay =             "http://earthquake.usgs.gov/earthquakes/catalogs/1day-M2.5.xml";         private const string FeedForPreviousWeek =             "http://earthquake.usgs.gov/earthquakes/catalogs/7day-M2.5.xml";           /// <summary>         /// Gets the earthquake data for the previous week.         /// </summary>         /// <returns>A queryable collection of <see cref="Earthquake"/> objects.</returns>         public IQueryable<Earthquake> GetEarthquakes()         {             var feed = GetFeed(FeedForPreviousWeek);             var list = new List<Earthquake>();               if ( feed != null )             {                 foreach ( var entry in feed.Items )                 {                     var quake = CreateEarthquake(entry);                     if ( quake != null )                     {                         list.Add(quake);                     }                 }             }               return list.AsQueryable();         }           /// <summary>         /// Creates an <see cref="Earthquake"/> object for each entry in the Atom feed.         /// </summary>         /// <param name="entry">The Atom entry.</param>         /// <returns></returns>         private Earthquake CreateEarthquake(SyndicationItem entry)         {             Earthquake quake = null;             string title = entry.Title.Text;             string summary = entry.Summary.Text;             string point = GetElementValue<String>(entry, "point");             string depth = GetElementValue<String>(entry, "elev");             string utcTime = null;             string localTime = null;             string depthDesc = null;             double? magnitude = null;             double? latitude = null;             double? longitude = null;             double? depthKm = null;               if ( !String.IsNullOrEmpty(title) && title.StartsWith("M") )             {                 title = title.Substring(2, title.IndexOf(',')-3).Trim();                 magnitude = TryParse(title);             }             if ( !String.IsNullOrEmpty(point) )             {                 var values = point.Split(' ');                 if ( values.Length == 2 )                 {                     latitude = TryParse(values[0]);                     longitude = TryParse(values[1]);                 }             }             if ( !String.IsNullOrEmpty(depth) )             {                 depthKm = TryParse(depth);                 if ( depthKm != null )                 {                     depthKm = Math.Round((-1 * depthKm.Value) / 100, 2);                 }             }             if ( !String.IsNullOrEmpty(summary) )             {                 summary = summary.Replace("</p>", "");                 var values = summary.Split(                     new string[] { "<p>" },                     StringSplitOptions.RemoveEmptyEntries);                   if ( values.Length == 3 )                 {                     var times = values[1].Split(                         new string[] { "<br>" },                         StringSplitOptions.RemoveEmptyEntries);                       if ( times.Length > 0 )                     {                         utcTime = times[0];                     }                     if ( times.Length > 1 )                     {                         localTime = times[1];                     }                       depthDesc = values[2];                     depthDesc = "Depth: " + depthDesc.Substring(depthDesc.IndexOf(":") + 2);                 }             }               if ( latitude != null && longitude != null )             {                 quake = new Earthquake()                 {                     Id = entry.Id,                     Title = entry.Title.Text,                     Summary = entry.Summary.Text,                     Date = entry.LastUpdatedTime.DateTime,                     Url = entry.Links.Select(l => Path.Combine(l.BaseUri.OriginalString,                         l.Uri.OriginalString)).FirstOrDefault(),                     Age = entry.Categories.Where(c => c.Label == "Age")                         .Select(c => c.Name).FirstOrDefault(),                     Magnitude = magnitude.GetValueOrDefault(),                     Latitude = latitude.GetValueOrDefault(),                     Longitude = longitude.GetValueOrDefault(),                     DepthInKm = depthKm.GetValueOrDefault(),                     DepthDesc = depthDesc,                     UtcTime = utcTime,                     LocalTime = localTime                 };             }               return quake;         }           private T GetElementValue<T>(SyndicationItem entry, String name)         {             var el = entry.ElementExtensions.Where(e => e.OuterName == name).FirstOrDefault();             T value = default(T);               if ( el != null )             {                 value = el.GetObject<T>();             }               return value;         }           private double? TryParse(String value)         {             double d;             if ( Double.TryParse(value, out d) )             {                 return d;             }             return null;         }           /// <summary>         /// Gets the feed at the specified URL.         /// </summary>         /// <param name="url">The URL.</param>         /// <returns>A <see cref="SyndicationFeed"/> object.</returns>         public static SyndicationFeed GetFeed(String url)         {             SyndicationFeed feed = null;               try             {                 log.Debug("Loading RSS feed: " + url);                   using ( var reader = XmlReader.Create(url) )                 {                     feed = SyndicationFeed.Load(reader);                 }             }             catch ( Exception ex )             {                 log.Error("Error occurred while loading RSS feed: " + url, ex);             }               return feed;         }     } }   The only method that will be generated in the client side proxy class, EarthquakeContext, will be the GetEarthquakes() method. The reason being that it is the only public instance method and it returns an IQueryable<Earthquake> collection that can be consumed by the client application. GetEarthquakes() calls the static GetFeed(String) method, which utilizes the built in SyndicationFeed API to load the external data feed. You will need to add a reference to the System.ServiceModel.Web library in order to take advantage of the RSS/Atom reader. The API will also allow you to create your own feeds to serve up in your applications. Model I have also created a Model folder and added a new class, Earthquake.cs. The Earthquake object will hold the various properties returned from the Atom feed. Here is a sample of the code for that class. Notice the [Key] attribute on the Id property, which is required by RIA Services to uniquely identify the entity. using System; using System.Collections.Generic; using System.Linq; using System.Runtime.Serialization; using System.ComponentModel.DataAnnotations;   namespace EarthquakeLocator.Web.Model {     /// <summary>     /// Represents an earthquake occurrence and related information.     /// </summary>     [DataContract]     public class Earthquake     {         /// <summary>         /// Gets or sets the id.         /// </summary>         /// <value>The id.</value>         [Key]         [DataMember]         public string Id { get; set; }           /// <summary>         /// Gets or sets the title.         /// </summary>         /// <value>The title.</value>         [DataMember]         public string Title { get; set; }           /// <summary>         /// Gets or sets the summary.         /// </summary>         /// <value>The summary.</value>         [DataMember]         public string Summary { get; set; }           // additional properties omitted     } }   View Model The recent trend to use the MVVM pattern for WPF and Silverlight provides a great way to separate the data and behavior logic out of the user interface layer of your client applications. I have chosen to use the MVVM Light Toolkit for the Earthquake Locator, but there are other options out there if you prefer another library. That said, I went ahead and created a ViewModel folder in the Silverlight project and added a EarthquakeViewModel class that derives from ViewModelBase. Here is the code: using System; using System.Collections.ObjectModel; using System.ComponentModel.Composition; using System.ComponentModel.Composition.Hosting; using Microsoft.Maps.MapControl; using GalaSoft.MvvmLight; using EarthquakeLocator.Web.Model; using EarthquakeLocator.Web.Services;   namespace EarthquakeLocator.ViewModel {     /// <summary>     /// Provides data for views displaying earthquake information.     /// </summary>     public class EarthquakeViewModel : ViewModelBase     {         [Import]         public EarthquakeContext Context;           /// <summary>         /// Initializes a new instance of the <see cref="EarthquakeViewModel"/> class.         /// </summary>         public EarthquakeViewModel()         {             var catalog = new AssemblyCatalog(GetType().Assembly);             var container = new CompositionContainer(catalog);             container.ComposeParts(this);             Initialize();         }           /// <summary>         /// Initializes a new instance of the <see cref="EarthquakeViewModel"/> class.         /// </summary>         /// <param name="context">The context.</param>         public EarthquakeViewModel(EarthquakeContext context)         {             Context = context;             Initialize();         }           private void Initialize()         {             MapCenter = new Location(20, -170);             ZoomLevel = 2;         }           #region Private Methods           private void OnAutoLoadDataChanged()         {             LoadEarthquakes();         }           private void LoadEarthquakes()         {             var query = Context.GetEarthquakesQuery();             Context.Earthquakes.Clear();               Context.Load(query, (op) =>             {                 if ( !op.HasError )                 {                     foreach ( var item in op.Entities )                     {                         Earthquakes.Add(item);                     }                 }             }, null);         }           #endregion Private Methods           #region Properties           private bool autoLoadData;         /// <summary>         /// Gets or sets a value indicating whether to auto load data.         /// </summary>         /// <value><c>true</c> if auto loading data; otherwise, <c>false</c>.</value>         public bool AutoLoadData         {             get { return autoLoadData; }             set             {                 if ( autoLoadData != value )                 {                     autoLoadData = value;                     RaisePropertyChanged("AutoLoadData");                     OnAutoLoadDataChanged();                 }             }         }           private ObservableCollection<Earthquake> earthquakes;         /// <summary>         /// Gets the collection of earthquakes to display.         /// </summary>         /// <value>The collection of earthquakes.</value>         public ObservableCollection<Earthquake> Earthquakes         {             get             {                 if ( earthquakes == null )                 {                     earthquakes = new ObservableCollection<Earthquake>();                 }                   return earthquakes;             }         }           private Location mapCenter;         /// <summary>         /// Gets or sets the map center.         /// </summary>         /// <value>The map center.</value>         public Location MapCenter         {             get { return mapCenter; }             set             {                 if ( mapCenter != value )                 {                     mapCenter = value;                     RaisePropertyChanged("MapCenter");                 }             }         }           private double zoomLevel;         /// <summary>         /// Gets or sets the zoom level.         /// </summary>         /// <value>The zoom level.</value>         public double ZoomLevel         {             get { return zoomLevel; }             set             {                 if ( zoomLevel != value )                 {                     zoomLevel = value;                     RaisePropertyChanged("ZoomLevel");                 }             }         }           #endregion Properties     } }   The EarthquakeViewModel class contains all of the properties that will be bound to by the various controls in our views. Be sure to read through the LoadEarthquakes() method, which handles calling the GetEarthquakes() method in our EarthquakeService via the EarthquakeContext proxy, and also transfers the loaded entities into the view model’s Earthquakes collection. Another thing to notice is what’s going on in the default constructor. I chose to use the Managed Extensibility Framework (MEF) for my composition needs, but you can use any dependency injection library or none at all. To allow the EarthquakeContext class to be discoverable by MEF, I added the following partial class so that I could supply the appropriate [Export] attribute: using System; using System.ComponentModel.Composition;   namespace EarthquakeLocator.Web.Services {     /// <summary>     /// The client side proxy for the EarthquakeService class.     /// </summary>     [Export]     public partial class EarthquakeContext     {     } }   One last piece I wanted to point out before moving on to the user interface, I added a client side partial class for the Earthquake entity that contains helper properties that we will bind to later: using System;   namespace EarthquakeLocator.Web.Model {     /// <summary>     /// Represents an earthquake occurrence and related information.     /// </summary>     public partial class Earthquake     {         /// <summary>         /// Gets the location based on the current Latitude/Longitude.         /// </summary>         /// <value>The location.</value>         public string Location         {             get { return String.Format("{0},{1}", Latitude, Longitude); }         }           /// <summary>         /// Gets the size based on the Magnitude.         /// </summary>         /// <value>The size.</value>         public double Size         {             get { return (Magnitude * 3); }         }     } }   View Now the fun part! Usually, I would create a Views folder to place all of my View controls in, but I took the easy way out and added the following XAML code to the default MainPage.xaml file. Be sure to add the bing prefix associating the Microsoft.Maps.MapControl namespace after adding the assembly reference to your project. The MVVM Light Toolkit project templates come with a ViewModelLocator class that you can use via a static resource, but I am instantiating the EarthquakeViewModel directly in my user control. I am setting the AutoLoadData property to true as a way to trigger the LoadEarthquakes() method call. The MapItemsControl found within the <bing:Map> control binds its ItemsSource property to the Earthquakes collection of the view model, and since it is an ObservableCollection<T>, we get the automatic two way data binding via the INotifyCollectionChanged interface. <UserControl x:Class="EarthquakeLocator.MainPage"     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"     xmlns:d="http://schemas.microsoft.com/expression/blend/2008"     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"     xmlns:bing="clr-namespace:Microsoft.Maps.MapControl;assembly=Microsoft.Maps.MapControl"     xmlns:vm="clr-namespace:EarthquakeLocator.ViewModel"     mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480" >     <UserControl.Resources>         <DataTemplate x:Key="EarthquakeTemplate">             <Ellipse Fill="Red" Stroke="Black" StrokeThickness="1"                      Width="{Binding Size}" Height="{Binding Size}"                      bing:MapLayer.Position="{Binding Location}"                      bing:MapLayer.PositionOrigin="Center">                 <ToolTipService.ToolTip>                     <StackPanel>                         <TextBlock Text="{Binding Title}" FontSize="14" FontWeight="Bold" />                         <TextBlock Text="{Binding UtcTime}" />                         <TextBlock Text="{Binding LocalTime}" />                         <TextBlock Text="{Binding DepthDesc}" />                     </StackPanel>                 </ToolTipService.ToolTip>             </Ellipse>         </DataTemplate>     </UserControl.Resources>       <UserControl.DataContext>         <vm:EarthquakeViewModel AutoLoadData="True" />     </UserControl.DataContext>       <Grid x:Name="LayoutRoot">           <bing:Map x:Name="map" CredentialsProvider="--Your-Bing-Maps-Key--"                   Center="{Binding MapCenter, Mode=TwoWay}"                   ZoomLevel="{Binding ZoomLevel, Mode=TwoWay}">             <bing:MapItemsControl ItemsSource="{Binding Earthquakes}"                                   ItemTemplate="{StaticResource EarthquakeTemplate}" />         </bing:Map>       </Grid> </UserControl>   The EarthquakeTemplate defines the Ellipse that will represent each earthquake, the Width and Height that are determined by the Magnitude, the Position on the map, and also the tooltip that will appear when we mouse over each data point. Running the application will give us the following result (shown with a tooltip example): That concludes this portion of our show but I plan on implementing additional functionality in later blog posts. Be sure to come back soon to see the next installments in this series. Enjoy!   Additional Resources USGS Earthquake Data Feeds Brad Abrams shows how RIA Services and MVVM can work together

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• Oracle Coherence, Split-Brain and Recovery Protocols In Detail

  - by Ricardo Ferreira

  This article provides a high level conceptual overview of Split-Brain scenarios in distributed systems. It will focus on a specific example of cluster communication failure and recovery in Oracle Coherence. This includes a discussion on the witness protocol (used to remove failed cluster members) and the panic protocol (used to resolve Split-Brain scenarios). Note that the removal of cluster members does not necessarily indicate a Split-Brain condition. Oracle Coherence does not (and cannot) detect a Split-Brain as it occurs, the condition is only detected when cluster members that previously lost contact with each other regain contact. Cluster Topology and Configuration In order to create an good didactic for the article, let's assume a cluster topology and configuration. In this example we have a six member cluster, consisting of one JVM on each physical machine. The member IDs are as follows: Member ID  IP Address  1  10.149.155.76  2  10.149.155.77  3  10.149.155.236  4  10.149.155.75  5  10.149.155.79  6  10.149.155.78 Members 1, 2, and 3 are connected to a switch, and members 4, 5, and 6 are connected to a second switch. There is a link between the two switches, which provides network connectivity between all of the machines. Member 1 is the first member to join this cluster, thus making it the senior member. Member 6 is the last member to join this cluster. Here is a log snippet from Member 6 showing the complete member set: 2010-02-26 15:27:57.390/3.062 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=main, member=6): Started DefaultCacheServer... SafeCluster: Name=cluster:0xDDEB Group{Address=224.3.5.3, Port=35465, TTL=4} MasterMemberSet ( ThisMember=Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) OldestMember=Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) ActualMemberSet=MemberSet(Size=6, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=5, Timestamp=2010-02-26 15:27:49.095, Address=10.149.155.79:8088, MachineId=1103, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:3229, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) RecycleMillis=120000 RecycleSet=MemberSet(Size=0, BitSetCount=0 ) ) At approximately 15:30, the connection between the two switches is severed: Thirty seconds later (the default packet timeout in development mode) the logs indicate communication failures across the cluster. In this example, the communication failure was caused by a network failure. In a production setting, this type of communication failure can have many root causes, including (but not limited to) network failures, excessive GC, high CPU utilization, swapping/virtual memory, and exceeding maximum network bandwidth. In addition, this type of failure is not necessarily indicative of a split brain. Any communication failure will be logged in this fashion. Member 2 logs a communication failure with Member 5: 2010-02-26 15:30:32.638/196.928 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=2): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=5, Timestamp=2010-02-26 15:27:49.095, Address=10.149.155.79:8088, MachineId=1103, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:3229, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) ) The Coherence clustering protocol (TCMP) is a reliable transport mechanism built on UDP. In order for the protocol to be reliable, it requires an acknowledgement (ACK) for each packet delivered. If a packet fails to be acknowledged within the configured timeout period, the Coherence cluster member will log a packet timeout (as seen in the log message above). When this occurs, the cluster member will consult with other members to determine who is at fault for the communication failure. If the witness members agree that the suspect member is at fault, the suspect is removed from the cluster. If the witnesses unanimously disagree, the accuser is removed. This process is known as the witness protocol. Since Member 2 cannot communicate with Member 5, it selects two witnesses (Members 1 and 4) to determine if the communication issue is with Member 5 or with itself (Member 2). However, Member 4 is on the switch that is no longer accessible by Members 1, 2 and 3; thus a packet timeout for member 4 is recorded as well: 2010-02-26 15:30:35.648/199.938 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=2): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) Member 1 has the ability to confirm the departure of member 4, however Member 6 cannot as it is also inaccessible. At the same time, Member 3 sends a request to remove Member 6, which is followed by a report from Member 3 indicating that Member 6 has departed the cluster: 2010-02-26 15:30:35.706/199.996 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=2): MemberLeft request for Member 6 received from Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) 2010-02-26 15:30:35.709/199.999 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=2): MemberLeft notification for Member 6 received from Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) The log for Member 3 determines how Member 6 departed the cluster: 2010-02-26 15:30:35.161/191.694 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=3): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) ) 2010-02-26 15:30:35.165/191.698 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=3): Member departure confirmed by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) ); removing Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) In this case, Member 3 happened to select two witnesses that it still had connectivity with (Members 1 and 2) thus resulting in a simple decision to remove Member 6. Given the departure of Member 6, Member 2 is left with a single witness to confirm the departure of Member 4: 2010-02-26 15:30:35.713/200.003 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=2): Member departure confirmed by MemberSet(Size=1, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) ); removing Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) In the meantime, Member 4 logs a missing heartbeat from the senior member. This message is also logged on Members 5 and 6. 2010-02-26 15:30:07.906/150.453 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=PacketListenerN, member=4): Scheduled senior member heartbeat is overdue; rejoining multicast group. Next, Member 4 logs a TcpRing failure with Member 2, thus resulting in the termination of Member 2: 2010-02-26 15:30:21.421/163.968 Oracle Coherence GE 3.5.3/465p2 <D4> (thread=Cluster, member=4): TcpRing: Number of socket exceptions exceeded maximum; last was "java.net.SocketTimeoutException: connect timed out"; removing the member: 2 For quick process termination detection, Oracle Coherence utilizes a feature called TcpRing which is a sparse collection of TCP/IP-based connections between different members in the cluster. Each member in the cluster is connected to at least one other member, which (if at all possible) is running on a different physical box. This connection is not used for any data transfer, only heartbeat communications are sent once a second per each link. If a certain number of exceptions are thrown while trying to re-establish a connection, the member throwing the exceptions is removed from the cluster. Member 5 logs a packet timeout with Member 3 and cites witnesses Members 4 and 6: 2010-02-26 15:30:29.791/165.037 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=5): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) 2010-02-26 15:30:29.798/165.044 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=5): Member departure confirmed by MemberSet(Size=2, BitSetCount=2 Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ); removing Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) Eventually we are left with two distinct clusters consisting of Members 1, 2, 3 and Members 4, 5, 6, respectively. In the latter cluster, Member 4 is promoted to senior member. The connection between the two switches is restored at 15:33. Upon the restoration of the connection, the cluster members immediately receive cluster heartbeats from the two senior members. In the case of Members 1, 2, and 3, the following is logged: 2010-02-26 15:33:14.970/369.066 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=1): The member formerly known as Member(Id=4, Timestamp=2010-02-26 15:30:35.341, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) has been forcefully evicted from the cluster, but continues to emit a cluster heartbeat; henceforth, the member will be shunned and its messages will be ignored. Likewise for Members 4, 5, and 6: 2010-02-26 15:33:14.343/336.890 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=4): The member formerly known as Member(Id=1, Timestamp=2010-02-26 15:30:31.64, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) has been forcefully evicted from the cluster, but continues to emit a cluster heartbeat; henceforth, the member will be shunned and its messages will be ignored. This message indicates that a senior heartbeat is being received from members that were previously removed from the cluster, in other words, something that should not be possible. For this reason, the recipients of these messages will initially ignore them. After several iterations of these messages, the existence of multiple clusters is acknowledged, thus triggering the panic protocol to reconcile this situation. When the presence of more than one cluster (i.e. Split-Brain) is detected by a Coherence member, the panic protocol is invoked in order to resolve the conflicting clusters and consolidate into a single cluster. The protocol consists of the removal of smaller clusters until there is one cluster remaining. In the case of equal size clusters, the one with the older Senior Member will survive. Member 1, being the oldest member, initiates the protocol: 2010-02-26 15:33:45.970/400.066 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=1): An existence of a cluster island with senior Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) containing 3 nodes have been detected. Since this Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) is the senior of an older cluster island, the panic protocol is being activated to stop the other island's senior and all junior nodes that belong to it. Member 3 receives the panic: 2010-02-26 15:33:45.803/382.336 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=3): Received panic from senior Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) caused by Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member 4, the senior member of the younger cluster, receives the kill message from Member 3: 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. In turn, Member 4 requests the departure of its junior members 5 and 6: 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. 2010-02-26 15:33:43.343/349.015 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=6): Received a Kill message from a valid Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer); stopping cluster service. Once Members 4, 5, and 6 restart, they rejoin the original cluster with senior member 1. The log below is from Member 4. Note that it receives a different member id when it rejoins the cluster. 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. 2010-02-26 15:33:46.921/369.468 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Service Cluster left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Invocation:InvocationService, member=4): Service InvocationService left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=OptimisticCache, member=4): Service OptimisticCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=ReplicatedCache, member=4): Service ReplicatedCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=DistributedCache, member=4): Service DistributedCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Invocation:Management, member=4): Service Management left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service Management with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service DistributedCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service ReplicatedCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service OptimisticCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service InvocationService with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member(Id=6, Timestamp=2010-02-26 15:33:47.046, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) left Cluster with senior member 4 2010-02-26 15:33:49.218/371.765 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=main, member=n/a): Restarting cluster 2010-02-26 15:33:49.421/371.968 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=n/a): Service Cluster joined the cluster with senior service member n/a 2010-02-26 15:33:49.625/372.172 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=n/a): This Member(Id=5, Timestamp=2010-02-26 15:33:50.499, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer, Edition=Grid Edition, Mode=Development, CpuCount=2, SocketCount=1) joined cluster "cluster:0xDDEB" with senior Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer, Edition=Grid Edition, Mode=Development, CpuCount=2, SocketCount=2) Cool isn't it?

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• ASR / SNMP on Exadata

  - by rene.kundersma

  Recently I worked with ASR on Exadata for multiple customers. ASR is a great functionality that enables your 'systems' to alert Oracle when hardware failures occur. Sun hardware is using ASM for sometime and since 2009/2010 this is also available for Exadata. My goal is not to re-write the documentation so for general information I like to refer to this link. So, where is this note about ? Well, it is about two things I experienced around setting up ASR. I like to provide my experience so others can be successful with ASR fast as well. (It is however expected that things will be updated in the latest documentation.) First, imagine yourself configuring SNMP traps to be sent to ASR. In this situation be sure to not erase any existing SNMP Subscribers settings for example the subscription to Enterprise Manager Grid Control or whatever you already subscribed for. So, when you have documentation stating to execute "cellcli -e alter cell snmpSubscriber=(host=, port=)" be sure to add existing snmpSubscribers when they exist. The syntax allows this: snmpSubscriber= ((host=host [,port=port] [,community=community][,type=ASR]) [,(host=host[,port=port][,community=community][,type=ASR])...) Second, when configuring SnmpSubscribers using DCLI you have to work with a slash to escape the brackets. Be sure to verify your SNMP settings after setting them because you might end up with a bracket in the 'asrs.state' file stating 'public\' in stead of 'public'. Having the extra slash after the word 'public' of course doesn't help when sending SNMP-traps: dcli -g dbs_group -l root -n "/opt/oracle.cellos/compmon/exadata_mon_hw_asr.pl -validate_snmp_subscriber -type asr" cn38: Sending test trap to destination - 173.25.100.43:162 cn38: (1). count - 50 Failed to run "/usr/bin/snmptrap -v 2c -c public\ -M "+/opt/oracle.cellos/compmon/" -m SUN-HW-TRAP-MIB 173.25.100.43:162 "" SUN-HW- TRAP-MIB::sunHwTrapTestTrap sunHwTrapSystemIdentifier s " Sun Oracle Database Machine secret" sunHwTrapChassisId s "secret" sunHwTrapProductName s "SUN FIRE X4170 SERVER" sunHwTrapTestMessage s "This is a test trap. Exadata Compute Server: cn38.oracle.com "" cn38: getaddrinfo: +/opt/oracle.cellos/compmon/ Name or service not known cn38: snmptrap: Unknown host (+/opt/oracle.cellos/compmon/) All together ASR is a great addition to Exadata that I highly recommend. Some excellent documentation is written on the implementation details and available on MyOracleSupport. See "Oracle Database Machine Monitoring (Doc ID 1110675.1)" Rene Kundersma Technical Architect Oracle Technology Services

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• Effectively implementing a game view using java

  - by kdavis8

  I am writing a 2d game in java. The game mechanics are similar to the Pokémon game boy advance series e.g. fire red, ruby, diamond and so on. I need a way to draw a huge map maybe 5000 by 5000 pixels and then load individual in game sprites to across the entirety of the map, like rendering a scene. Game sprites would be things like terrain objects, trees, rocks, bushes, also houses, castles, NPC's and so on. But i also need to implement some kind of camera view class that focuses on the player. the camera view class needs to follow the characters movements throughout the game map but it also needs to clip the rest of the map away from the user's field of view, so that the user can only see the arbitrary proximity adjacent to the player's sprite. The proximity's range could be something like 500 pixels in every direction around the player’s sprite. On top of this, i need to implement an independent resolution for the game world so that the game view will be uniform on all screen sizes and screen resolutions. I know that this does sound like a handful and may fall under the category of multiple questions, but the questions are all related and any advice would be very much appreciated. I don’t need a full source code listing but maybe some pointers to effective java API classes that could make doing what i need to do a lot simpler. Also any algorithmic/ design advice would greatly benefit me as well. example of what i am trying to do in source code form below package myPackage; /** * The Purpose of GameView is to: Render a scene using Scene class, Create a * clipping pane using CameraView class, and finally instantiate a coordinate * grid using Path class. * * Once all of these things have been done, GameView class should then be * instantiated and used jointly with its helper classes. CameraView should be * used as the main drawing image. CameraView is the the window to the game * world.Scene passes data constantly to CameraView so that the entire map flows * smoothly. Path uses the x and y coordinates from camera view to construct * cells for path finding algorithms. */ public class GameView { // Scene is a helper class to game view. it renders the entire map to memory // for the camera view. Scene scene; // Camera View is a helper class to game view. It clips the Scene into a // small image that follows the players coordinates. CameraView Camera; // Path is a helper class to game view. It observes and calculates the // coordinates of camera view and divides them into Grids/Cells for Path // finding. Path path; // this represents the player and has a getSprite() method that will return // the current frame column row combination of the passed sprite sheet. Sprite player; }

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• Travelling MVP #1: Visit to SharePoint User Group Finland

  - by DigiMortal

  My first self organized trip this autumn was visit to SharePoint User Group Finland community evening. As active community leaders who make things like these possible they are worth mentioning and on spug.fi side there was Jussi Roine the one who invited me. Here is my short review about my trip to Helsinki. User group meeting As Helsinki is near Tallinn I went there using ship. It was easy to get from sea port to venue and I had also some minutes of time to visit academic book store. Community evening was held on the ground floor of one city center hotel and room was conveniently located near hotel bar and restaurant. Here is the meeting schedule: Welcome (Jussi Roine) OpenText application archiving and governance for SharePoint (Bernd Hennicke, OpenText) Using advanced C# features in SharePoint development (Alexey Sadomov, NED Consulting) Optimizing public-facing internet sites for SharePoint (Gunnar Peipman) After meeting, of course, local dudes doesn’t walk away but continue with some beers and discussion. Sessions After welcome words by Jussi there was session by Bernd Hennicke who spoke about OpenText. His session covered OpenText history and current moment. After this introduction he spoke about OpenText products for SharePoint and gave the audience good overview about where their SharePoint extensions fit in big picture. I usually don’t like those vendors sessions but this one was good. I mean vendor dudes were not aggressively selling something. They were way different – kind people who introduced their stuff and later answered questions. They acted like good guests. Second speaker was Alexey Sadomov who is working on SharePoint development projects. He introduced some ways how to get over some limitations of SharePoint. I don’t go here deeply with his session but it’s worth to mention that this session was strong one. It is not rear case when developers have to make nasty hacks to SharePoint. I mean really nasty hacks. Often these hacks are long blocks of code that uses terrible techniques to achieve the result. Alexey introduced some very much civilized ways about how to apply hacks. Alex Sadomov, SharePoint MVP, speaking about SharePoint coding tips and tricks on C# I spoke about how I optimized caching of Estonian Microsoft community portal that runs on SharePoint Server and that uses publishing infrastructure. I made no actual demos on SharePoint because I wanted to focus on optimizing process and share some experiences about how to get caches optimized and how to measure caches. Networking After official part there was time to talk and discuss with people. Finns are cool – they have beers and they are glad. It was not big community event but people were like one good family. Developers there work often for big companies and it was very interesting to me to hear about their experiences with SharePoint. One thing was a little bit surprising for me – SharePoint guys in Finland are talking actively also about Office 365 and online SharePoint. It doesn’t happen often here in Estonia. I had to leave a little bit 21:00 to get to my ship back to Tallinn. I am sure spug.fi dudes continued nice evening and they had at least same good time as I did. Do I want to go back to Finland and meet these guys again? Yes, sure, let’s do it again! :)

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• URL Routing in ASP.NET 4.0

  In the .NET Framework 3.5 SP1, Microsoft introduced ASP.NET Routing, which decouples the URL of a resource from the physical file on the web server. With ASP.NET Routing you, the developer, define routing rules map route patterns to a class that generates the content. For example, you might indicate that the URL Categories/CategoryName maps to a class that takes the CategoryName and generates HTML that lists that category's products in a grid. With such a mapping, users could view products for the Beverages category by visiting www.yoursite.com/Categories/Beverages. In .NET 3.5 SP1, ASP.NET Routing was primarily designed for ASP.NET MVC applications, although as discussed in Using ASP.NET Routing Without ASP.NET MVC it is possible to implement ASP.NET Routing in a Web Forms application, as well. However, implementing ASP.NET Routing in a Web Forms application involves a bit of seemingly excessive legwork. In a Web Forms scenario we typically want to map a routing pattern to an actual ASP.NET page. To do so we need to create a route handler class that is invoked when the routing URL is requested and, in a sense, dispatches the request to the appropriate ASP.NET page. For instance, to map a route to a physical file, such as mapping Categories/CategoryName to ShowProductsByCategory.aspx - requires three steps: (1) Define the mapping in Global.asax, which maps a route pattern to a route handler class; (2) Create the route handler class, which is responsible for parsing the URL, storing any route parameters into some location that is accessible to the target page (such as HttpContext.Items), and returning an instance of the target page or HTTP Handler that handles the requested route; and (3) writing code in the target page to grab the route parameters and use them in rendering its content. Given how much effort it took to just read the preceding sentence (let alone write it) you can imagine that implementing ASP.NET Routing in a Web Forms application is not necessarily the most straightforward task. The good news is that ASP.NET 4.0 has greatly simplified ASP.NET Routing for Web Form applications by adding a number of classes and helper methods that can be used to encapsulate the aforementioned complexity. With ASP.NET 4.0 it's easier to define the routing rules and there's no need to create a custom route handling class. This article details these enhancements. Read on to learn more! Read More >

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• Big Data – Buzz Words: What is MapReduce – Day 7 of 21

  - by Pinal Dave

  In yesterday’s blog post we learned what is Hadoop. In this article we will take a quick look at one of the four most important buzz words which goes around Big Data – MapReduce. What is MapReduce? MapReduce was designed by Google as a programming model for processing large data sets with a parallel, distributed algorithm on a cluster. Though, MapReduce was originally Google proprietary technology, it has been quite a generalized term in the recent time. MapReduce comprises a Map() and Reduce() procedures. Procedure Map() performance filtering and sorting operation on data where as procedure Reduce() performs a summary operation of the data. This model is based on modified concepts of the map and reduce functions commonly available in functional programing. The library where procedure Map() and Reduce() belongs is written in many different languages. The most popular free implementation of MapReduce is Apache Hadoop which we will explore tomorrow. Advantages of MapReduce Procedures The MapReduce Framework usually contains distributed servers and it runs various tasks in parallel to each other. There are various components which manages the communications between various nodes of the data and provides the high availability and fault tolerance. Programs written in MapReduce functional styles are automatically parallelized and executed on commodity machines. The MapReduce Framework takes care of the details of partitioning the data and executing the processes on distributed server on run time. During this process if there is any disaster the framework provides high availability and other available modes take care of the responsibility of the failed node. As you can clearly see more this entire MapReduce Frameworks provides much more than just Map() and Reduce() procedures; it provides scalability and fault tolerance as well. A typical implementation of the MapReduce Framework processes many petabytes of data and thousands of the processing machines. How do MapReduce Framework Works? A typical MapReduce Framework contains petabytes of the data and thousands of the nodes. Here is the basic explanation of the MapReduce Procedures which uses this massive commodity of the servers. Map() Procedure There is always a master node in this infrastructure which takes an input. Right after taking input master node divides it into smaller sub-inputs or sub-problems. These sub-problems are distributed to worker nodes. A worker node later processes them and does necessary analysis. Once the worker node completes the process with this sub-problem it returns it back to master node. Reduce() Procedure All the worker nodes return the answer to the sub-problem assigned to them to master node. The master node collects the answer and once again aggregate that in the form of the answer to the original big problem which was assigned master node. The MapReduce Framework does the above Map () and Reduce () procedure in the parallel and independent to each other. All the Map() procedures can run parallel to each other and once each worker node had completed their task they can send it back to master code to compile it with a single answer. This particular procedure can be very effective when it is implemented on a very large amount of data (Big Data). The MapReduce Framework has five different steps: Preparing Map() Input Executing User Provided Map() Code Shuffle Map Output to Reduce Processor Executing User Provided Reduce Code Producing the Final Output Here is the Dataflow of MapReduce Framework: Input Reader Map Function Partition Function Compare Function Reduce Function Output Writer In a future blog post of this 31 day series we will explore various components of MapReduce in Detail. MapReduce in a Single Statement MapReduce is equivalent to SELECT and GROUP BY of a relational database for a very large database. Tomorrow In tomorrow’s blog post we will discuss Buzz Word – HDFS. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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• OBIEE 11.1.1 - Introduction to OBIEE 11g Full Sample App

  - by user809526

  Isn't it nice to discover OBIEE 11g around a nice "How To" catalog of features? to observe OBI and Essbase relationships at work? to discover TimesTen? The OBIEE 11g Full Sample App (FSA) is a comprehensive collection of examples designed to demonstrate the latest Oracle BIEE 11g capabilities and design best practices: Enhanced visualizations as Geo-spacial maps and interactive dashboards, Action Framework,  BI Publisher, Scorecard and Strategy Management, Mobile style sheets, Semantic layer modeling, Multi-source federation, Integration with products such as Essbase, Oracle OLAP, ODM, TimesTen, ODI and more The FSA is intended to be comprehensive, it is big (see CAVEAT below). The FSA is not an Oracle product, it is a good will free deployment of OBIEE/Essbase designed to exemplify OBIEE features, infrastructure and security around the Fusion Middleware components. Its contents and code are distributed free for demonstrative purposes only. It is neither maintained nor supported by Oracle as a licensed product. The OBIEE Full Sample App is independent of the default Sample App that comes with the OBIEE product. BENEFITS The FSA helps as a demonstrator of OBIEE 11g best practices, a tutorial, an environment "Test & Scrap", a SR bench (regression, conflicts), a tuning bench, a quick ready made POC seed for projects, a security options environment, ... The FSA - Is organized around a catalog of functional features - Has been deployed over 1000 times, it should be stable RELEASE The Full Sample App (V107) is bound to OBIEE 11.1.1.5 and Essbase 11.1.2.1 (November 2011). The FSA release dates are independent of the Product GA date (OBIEE). In early December 2011, a new functional Patch (V110) is released. It is easily applied (in less than 15 mins) on top of OBIEE SampleApp 11.1.1.5 (V107). The patch (V110) includes additional functional examples:        1. Web Catalog Statistics Application: Provides detailed insight into your web catalog content, dormant catalog objects, webcat impact analysis for metadata changes and more        2. Data inflation Scripts: A set of simple SQL procedures to quickly inflate SampleApp Fact and Dimension data to millions of records in a few minutes        3. Public Content Extensions Framework: A patching framework for public examples and contributions leveraging SampleApp        4. Additional report examples (including bridge report, external chart integrations) and bug fixes DISTRIBUTION as VBox image (November 2011) The ready made VBox image is designed to run on Virtual Box. It can be converted to VMware (see another BLOG). 1/ http://www.oracle.com/technetwork/middleware/bi-foundation/obiee-samples-167534.html VBox Image Deployment Guide Sampleapp_v107_GA.ovf - VBox image key file The above http URL provides the user:password for the ftp URLs below. 2/ ftp://user:[email protected]/static/SampleAppV107/ 12 "7-zip" files Sampleapp_v107_GA_7_20.7z.001 -> .012 We recommend 7-zip file manager for unzipping (http://www.7-zip.org/). Select Unzip here option, it will create the contents under a directory named "SampleApp_10722". On Windows, it is important to download and save zip file under the root directory (e.g. C:\ or D:\) because of possible long pathnames. 3/ ftp://user:[email protected]/static/SampleAppV107/Unzipped_Version/ 4 files Sampleapp_v107_GA-disk[1234].vmdk Important note: Check the provided checksums (md5sum). Please do it! DISTRIBUTION as Installation files for existing OBI 11.1.1.5 (November 2011) http://www.oracle.com/technetwork/middleware/bi-foundation/obiee-samples-167534.html Install files Deployment Guide SampleApp_10722_1.zip - 198 MB CAVEAT Many computers have RAM chips problems that keep often silent ... until you manipulate big files. It is strongly advised you run some memory check program eg MEMTEST in GRUB boot manager. Running md5sum repeatedly onto the very same big file must be consistent [same result], else a hardware memory problem is suspected. For Virtual Box, you should most likely enable VT-X (Vanderpool) hardware virtualization in BIOS. A free disk space of 80 GB is required to perform safely the VBox image installation. A Virtual Machine of minimum 6 to 7 GB memory fits the needs of combining OBIEE and Essbase execution.

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