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  • Best way to have common class shared by both C++ and Ruby?

    - by shuttle87
    I am currently working on a project where a team of us are designing a game, all of us are proficient in ruby and some (but not all) of us are proficient in c++. Initially we made the backend in ruby but we ported it to c++ for more speed. The c++ port of the backend has exactly the same features and algorithms as the original ruby code. However we still have a bunch of code in ruby that does useful things but we want it to now get the data from the c++ classes. Our first thought was that we could save some of the data structures in something like XML or redis and call that, but some of the developers don't like that idea. We don't need anything particularly complex data structures to be passed between the different parts of the code, just tuples, strings and ints. Is there any way of integrating the ruby code so that it can call the c++ stuff natively? Will we need to embed code? Will we have to make a ruby extension? If so are there any good resources/tutorials you could suggest? For example say we have this code in the c++ backend: class The_game{ private: bool printinfo; //print the player diagnostic info at the beginning if true int numplayers; std::vector<Player*> players; string current_action; int action_is_on; // the index of the player in the players array that the action is now on //more code here public: Table(std::vector<Player *> in_players, std::vector<Statistics *> player_stats ,const int in_numplayers); ~Table(); void play_game(); History actions_history; }; class History{ private: int action_sequence_number; std::vector<Action*> hand_actions; public: void print_history(); void add_action(Action* the_action_to_be_added); int get_action_sequence_number(){ return action_sequence_number;} bool history_actions_are_equal(); int last_action_size(int street,int number_of_actions_ago); History(); ~History(); }; Is there any way to natively call something in the actions_history via The_game object in ruby? (The objects in the original ruby code all had the same names and functionality) By this I mean: class MyRubyClass def method1(arg1) puts arg1 self.f() # ... but still available puts cpp_method.the_current_game.actions_history.get_action_sequence_number() end # Constructor: def initialize(arg) puts "In constructor with arg #{arg}" #get the c++ object here and call it cpp_method end end Is this possible? Any advice or suggestions are appreciated.

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  • Understanding flow of object creation

    - by Boris Mandovskes
    I'm new to java and I wonder if there is simple way to know flow like the following of object creation, I'm using eclipse and when I write new ObjectInputStream and press CTRL+SPACE. I don't see any option that I can enter new BufferedInputStream (I have copied the code from example) and than to create new object for FileInputStream etc. in = new ObjectInputStream(new BufferedInputStream(new FileInputStream("emp.dat"))); List temp = (List)in.readObject(); I give that example since this is the first time that I saw this kind of creation new object flow and I want to use some best practice for the next times.

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  • C# class code loaded in RAM ?

    - by Spi1988
    hi, I would like to know whether the actual code of a C# class gets loaded in RAM when you instantiate the class? So for example if I have 2 Classes CLASS A , CLASS B, where class A has 10000 lines of code but just 1 field, an int. And class B has 10 lines of code and also 1 field an int as well. If I instantiate Class A will it take more RAM than Class B due to its lines of code ? A supplementary question, If the lines of code are loaded in memory together with the class, will they be loaded for every instance of the class? or just once for all the instances? Thanks in advance.

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  • factory class, wrong number of arguments being passed to subclass constructor

    - by Hugh Bothwell
    I was looking at Python: Exception in the separated module works wrong which uses a multi-purpose GnuLibError class to 'stand in' for a variety of different errors. Each sub-error has its own ID number and error format string. I figured it would be better written as a hierarchy of Exception classes, and set out to do so: class GNULibError(Exception): sub_exceptions = 0 # patched with dict of subclasses once subclasses are created err_num = 0 err_format = None def __new__(cls, *args): print("new {}".format(cls)) # DEBUG if len(args) and args[0] in GNULibError.sub_exceptions: print(" factory -> {} {}".format(GNULibError.sub_exceptions[args[0]], args[1:])) # DEBUG return super(GNULibError, cls).__new__(GNULibError.sub_exceptions[args[0]], *(args[1:])) else: print(" plain {} {}".format(cls, args)) # DEBUG return super(GNULibError, cls).__new__(cls, *args) def __init__(self, *args): cls = type(self) print("init {} {}".format(cls, args)) # DEBUG self.args = args if cls.err_format is None: self.message = str(args) else: self.message = "[GNU Error {}] ".format(cls.err_num) + cls.err_format.format(*args) def __str__(self): return self.message def __repr__(self): return '{}{}'.format(type(self).__name__, self.args) class GNULibError_Directory(GNULibError): err_num = 1 err_format = "destination directory does not exist: {}" class GNULibError_Config(GNULibError): err_num = 2 err_format = "configure file does not exist: {}" class GNULibError_Module(GNULibError): err_num = 3 err_format = "selected module does not exist: {}" class GNULibError_Cache(GNULibError): err_num = 4 err_format = "{} is expected to contain gl_M4_BASE({})" class GNULibError_Sourcebase(GNULibError): err_num = 5 err_format = "missing sourcebase argument: {}" class GNULibError_Docbase(GNULibError): err_num = 6 err_format = "missing docbase argument: {}" class GNULibError_Testbase(GNULibError): err_num = 7 err_format = "missing testsbase argument: {}" class GNULibError_Libname(GNULibError): err_num = 8 err_format = "missing libname argument: {}" # patch master class with subclass reference # (TO DO: auto-detect all available subclasses instead of hardcoding them) GNULibError.sub_exceptions = { 1: GNULibError_Directory, 2: GNULibError_Config, 3: GNULibError_Module, 4: GNULibError_Cache, 5: GNULibError_Sourcebase, 6: GNULibError_Docbase, 7: GNULibError_Testbase, 8: GNULibError_Libname } This starts out with GNULibError as a factory class - if you call it with an error number belonging to a recognized subclass, it returns an object belonging to that subclass, otherwise it returns itself as a default error type. Based on this code, the following should be exactly equivalent (but aren't): e = GNULibError(3, 'missing.lib') f = GNULibError_Module('missing.lib') print e # -> '[GNU Error 3] selected module does not exist: 3' print f # -> '[GNU Error 3] selected module does not exist: missing.lib' I added some strategic print statements, and the error seems to be in GNULibError.__new__: >>> e = GNULibError(3, 'missing.lib') new <class '__main__.GNULibError'> factory -> <class '__main__.GNULibError_Module'> ('missing.lib',) # good... init <class '__main__.GNULibError_Module'> (3, 'missing.lib') # NO! ^ why? I call the subclass constructor as subclass.__new__(*args[1:]) - this should drop the 3, the subclass type ID - and yet its __init__ is still getting the 3 anyway! How can I trim the argument list that gets passed to subclass.__init__?

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  • An Xml Serializable PropertyBag Dictionary Class for .NET

    - by Rick Strahl
    I don't know about you but I frequently need property bags in my applications to store and possibly cache arbitrary data. Dictionary<T,V> works well for this although I always seem to be hunting for a more specific generic type that provides a string key based dictionary. There's string dictionary, but it only works with strings. There's Hashset<T> but it uses the actual values as keys. In most key value pair situations for me string is key value to work off. Dictionary<T,V> works well enough, but there are some issues with serialization of dictionaries in .NET. The .NET framework doesn't do well serializing IDictionary objects out of the box. The XmlSerializer doesn't support serialization of IDictionary via it's default serialization, and while the DataContractSerializer does support IDictionary serialization it produces some pretty atrocious XML. What doesn't work? First off Dictionary serialization with the Xml Serializer doesn't work so the following fails: [TestMethod] public void DictionaryXmlSerializerTest() { var bag = new Dictionary<string, object>(); bag.Add("key", "Value"); bag.Add("Key2", 100.10M); bag.Add("Key3", Guid.NewGuid()); bag.Add("Key4", DateTime.Now); bag.Add("Key5", true); bag.Add("Key7", new byte[3] { 42, 45, 66 }); TestContext.WriteLine(this.ToXml(bag)); } public string ToXml(object obj) { if (obj == null) return null; StringWriter sw = new StringWriter(); XmlSerializer ser = new XmlSerializer(obj.GetType()); ser.Serialize(sw, obj); return sw.ToString(); } The error you get with this is: System.NotSupportedException: The type System.Collections.Generic.Dictionary`2[[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089],[System.Object, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]] is not supported because it implements IDictionary. Got it! BTW, the same is true with binary serialization. Running the same code above against the DataContractSerializer does work: [TestMethod] public void DictionaryDataContextSerializerTest() { var bag = new Dictionary<string, object>(); bag.Add("key", "Value"); bag.Add("Key2", 100.10M); bag.Add("Key3", Guid.NewGuid()); bag.Add("Key4", DateTime.Now); bag.Add("Key5", true); bag.Add("Key7", new byte[3] { 42, 45, 66 }); TestContext.WriteLine(this.ToXmlDcs(bag)); } public string ToXmlDcs(object value, bool throwExceptions = false) { var ser = new DataContractSerializer(value.GetType(), null, int.MaxValue, true, false, null); MemoryStream ms = new MemoryStream(); ser.WriteObject(ms, value); return Encoding.UTF8.GetString(ms.ToArray(), 0, (int)ms.Length); } This DOES work but produces some pretty heinous XML (formatted with line breaks and indentation here): <ArrayOfKeyValueOfstringanyType xmlns="http://schemas.microsoft.com/2003/10/Serialization/Arrays" xmlns:i="http://www.w3.org/2001/XMLSchema-instance"> <KeyValueOfstringanyType> <Key>key</Key> <Value i:type="a:string" xmlns:a="http://www.w3.org/2001/XMLSchema">Value</Value> </KeyValueOfstringanyType> <KeyValueOfstringanyType> <Key>Key2</Key> <Value i:type="a:decimal" xmlns:a="http://www.w3.org/2001/XMLSchema">100.10</Value> </KeyValueOfstringanyType> <KeyValueOfstringanyType> <Key>Key3</Key> <Value i:type="a:guid" xmlns:a="http://schemas.microsoft.com/2003/10/Serialization/">2cd46d2a-a636-4af4-979b-e834d39b6d37</Value> </KeyValueOfstringanyType> <KeyValueOfstringanyType> <Key>Key4</Key> <Value i:type="a:dateTime" xmlns:a="http://www.w3.org/2001/XMLSchema">2011-09-19T17:17:05.4406999-07:00</Value> </KeyValueOfstringanyType> <KeyValueOfstringanyType> <Key>Key5</Key> <Value i:type="a:boolean" xmlns:a="http://www.w3.org/2001/XMLSchema">true</Value> </KeyValueOfstringanyType> <KeyValueOfstringanyType> <Key>Key7</Key> <Value i:type="a:base64Binary" xmlns:a="http://www.w3.org/2001/XMLSchema">Ki1C</Value> </KeyValueOfstringanyType> </ArrayOfKeyValueOfstringanyType> Ouch! That seriously hurts the eye! :-) Worse though it's extremely verbose with all those repetitive namespace declarations. It's good to know that it works in a pinch, but for a human readable/editable solution or something lightweight to store in a database it's not quite ideal. Why should I care? As a little background, in one of my applications I have a need for a flexible property bag that is used on a free form database field on an otherwise static entity. Basically what I have is a standard database record to which arbitrary properties can be added in an XML based string field. I intend to expose those arbitrary properties as a collection from field data stored in XML. The concept is pretty simple: When loading write the data to the collection, when the data is saved serialize the data into an XML string and store it into the database. When reading the data pick up the XML and if the collection on the entity is accessed automatically deserialize the XML into the Dictionary. (I'll talk more about this in another post). While the DataContext Serializer would work, it's verbosity is problematic both for size of the generated XML strings and the fact that users can manually edit this XML based property data in an advanced mode. A clean(er) layout certainly would be preferable and more user friendly. Custom XMLSerialization with a PropertyBag Class So… after a bunch of experimentation with different serialization formats I decided to create a custom PropertyBag class that provides for a serializable Dictionary. It's basically a custom Dictionary<TType,TValue> implementation with the keys always set as string keys. The result are PropertyBag<TValue> and PropertyBag (which defaults to the object type for values). The PropertyBag<TType> and PropertyBag classes provide these features: Subclassed from Dictionary<T,V> Implements IXmlSerializable with a cleanish XML format ToXml() and FromXml() methods to export and import to and from XML strings Static CreateFromXml() method to create an instance It's simple enough as it's merely a Dictionary<string,object> subclass but that supports serialization to a - what I think at least - cleaner XML format. The class is super simple to use: [TestMethod] public void PropertyBagTwoWayObjectSerializationTest() { var bag = new PropertyBag(); bag.Add("key", "Value"); bag.Add("Key2", 100.10M); bag.Add("Key3", Guid.NewGuid()); bag.Add("Key4", DateTime.Now); bag.Add("Key5", true); bag.Add("Key7", new byte[3] { 42,45,66 } ); bag.Add("Key8", null); bag.Add("Key9", new ComplexObject() { Name = "Rick", Entered = DateTime.Now, Count = 10 }); string xml = bag.ToXml(); TestContext.WriteLine(bag.ToXml()); bag.Clear(); bag.FromXml(xml); Assert.IsTrue(bag["key"] as string == "Value"); Assert.IsInstanceOfType( bag["Key3"], typeof(Guid)); Assert.IsNull(bag["Key8"]); //Assert.IsNull(bag["Key10"]); Assert.IsInstanceOfType(bag["Key9"], typeof(ComplexObject)); } This uses the PropertyBag class which uses a PropertyBag<string,object> - which means it returns untyped values of type object. I suspect for me this will be the most common scenario as I'd want to store arbitrary values in the PropertyBag rather than one specific type. The same code with a strongly typed PropertyBag<decimal> looks like this: [TestMethod] public void PropertyBagTwoWayValueTypeSerializationTest() { var bag = new PropertyBag<decimal>(); bag.Add("key", 10M); bag.Add("Key1", 100.10M); bag.Add("Key2", 200.10M); bag.Add("Key3", 300.10M); string xml = bag.ToXml(); TestContext.WriteLine(bag.ToXml()); bag.Clear(); bag.FromXml(xml); Assert.IsTrue(bag.Get("Key1") == 100.10M); Assert.IsTrue(bag.Get("Key3") == 300.10M); } and produces typed results of type decimal. The types can be either value or reference types the combination of which actually proved to be a little more tricky than anticipated due to null and specific string value checks required - getting the generic typing right required use of default(T) and Convert.ChangeType() to trick the compiler into playing nice. Of course the whole raison d'etre for this class is the XML serialization. You can see in the code above that we're doing a .ToXml() and .FromXml() to serialize to and from string. The XML produced for the first example looks like this: <?xml version="1.0" encoding="utf-8"?> <properties> <item> <key>key</key> <value>Value</value> </item> <item> <key>Key2</key> <value type="decimal">100.10</value> </item> <item> <key>Key3</key> <value type="___System.Guid"> <guid>f7a92032-0c6d-4e9d-9950-b15ff7cd207d</guid> </value> </item> <item> <key>Key4</key> <value type="datetime">2011-09-26T17:45:58.5789578-10:00</value> </item> <item> <key>Key5</key> <value type="boolean">true</value> </item> <item> <key>Key7</key> <value type="base64Binary">Ki1C</value> </item> <item> <key>Key8</key> <value type="nil" /> </item> <item> <key>Key9</key> <value type="___Westwind.Tools.Tests.PropertyBagTest+ComplexObject"> <ComplexObject> <Name>Rick</Name> <Entered>2011-09-26T17:45:58.5789578-10:00</Entered> <Count>10</Count> </ComplexObject> </value> </item> </properties>   The format is a bit cleaner than the DataContractSerializer. Each item is serialized into <key> <value> pairs. If the value is a string no type information is written. Since string tends to be the most common type this saves space and serialization processing. All other types are attributed. Simple types are mapped to XML types so things like decimal, datetime, boolean and base64Binary are encoded using their Xml type values. All other types are embedded with a hokey format that describes the .NET type preceded by a three underscores and then are encoded using the XmlSerializer. You can see this best above in the ComplexObject encoding. For custom types this isn't pretty either, but it's more concise than the DCS and it works as long as you're serializing back and forth between .NET clients at least. The XML generated from the second example that uses PropertyBag<decimal> looks like this: <?xml version="1.0" encoding="utf-8"?> <properties> <item> <key>key</key> <value type="decimal">10</value> </item> <item> <key>Key1</key> <value type="decimal">100.10</value> </item> <item> <key>Key2</key> <value type="decimal">200.10</value> </item> <item> <key>Key3</key> <value type="decimal">300.10</value> </item> </properties>   How does it work As I mentioned there's nothing fancy about this solution - it's little more than a subclass of Dictionary<T,V> that implements custom Xml Serialization and a couple of helper methods that facilitate getting the XML in and out of the class more easily. But it's proven very handy for a number of projects for me where dynamic data storage is required. Here's the code: /// <summary> /// Creates a serializable string/object dictionary that is XML serializable /// Encodes keys as element names and values as simple values with a type /// attribute that contains an XML type name. Complex names encode the type /// name with type='___namespace.classname' format followed by a standard xml /// serialized format. The latter serialization can be slow so it's not recommended /// to pass complex types if performance is critical. /// </summary> [XmlRoot("properties")] public class PropertyBag : PropertyBag<object> { /// <summary> /// Creates an instance of a propertybag from an Xml string /// </summary> /// <param name="xml">Serialize</param> /// <returns></returns> public static PropertyBag CreateFromXml(string xml) { var bag = new PropertyBag(); bag.FromXml(xml); return bag; } } /// <summary> /// Creates a serializable string for generic types that is XML serializable. /// /// Encodes keys as element names and values as simple values with a type /// attribute that contains an XML type name. Complex names encode the type /// name with type='___namespace.classname' format followed by a standard xml /// serialized format. The latter serialization can be slow so it's not recommended /// to pass complex types if performance is critical. /// </summary> /// <typeparam name="TValue">Must be a reference type. For value types use type object</typeparam> [XmlRoot("properties")] public class PropertyBag<TValue> : Dictionary<string, TValue>, IXmlSerializable { /// <summary> /// Not implemented - this means no schema information is passed /// so this won't work with ASMX/WCF services. /// </summary> /// <returns></returns> public System.Xml.Schema.XmlSchema GetSchema() { return null; } /// <summary> /// Serializes the dictionary to XML. Keys are /// serialized to element names and values as /// element values. An xml type attribute is embedded /// for each serialized element - a .NET type /// element is embedded for each complex type and /// prefixed with three underscores. /// </summary> /// <param name="writer"></param> public void WriteXml(System.Xml.XmlWriter writer) { foreach (string key in this.Keys) { TValue value = this[key]; Type type = null; if (value != null) type = value.GetType(); writer.WriteStartElement("item"); writer.WriteStartElement("key"); writer.WriteString(key as string); writer.WriteEndElement(); writer.WriteStartElement("value"); string xmlType = XmlUtils.MapTypeToXmlType(type); bool isCustom = false; // Type information attribute if not string if (value == null) { writer.WriteAttributeString("type", "nil"); } else if (!string.IsNullOrEmpty(xmlType)) { if (xmlType != "string") { writer.WriteStartAttribute("type"); writer.WriteString(xmlType); writer.WriteEndAttribute(); } } else { isCustom = true; xmlType = "___" + value.GetType().FullName; writer.WriteStartAttribute("type"); writer.WriteString(xmlType); writer.WriteEndAttribute(); } // Actual deserialization if (!isCustom) { if (value != null) writer.WriteValue(value); } else { XmlSerializer ser = new XmlSerializer(value.GetType()); ser.Serialize(writer, value); } writer.WriteEndElement(); // value writer.WriteEndElement(); // item } } /// <summary> /// Reads the custom serialized format /// </summary> /// <param name="reader"></param> public void ReadXml(System.Xml.XmlReader reader) { this.Clear(); while (reader.Read()) { if (reader.NodeType == XmlNodeType.Element && reader.Name == "key") { string xmlType = null; string name = reader.ReadElementContentAsString(); // item element reader.ReadToNextSibling("value"); if (reader.MoveToNextAttribute()) xmlType = reader.Value; reader.MoveToContent(); TValue value; if (xmlType == "nil") value = default(TValue); // null else if (string.IsNullOrEmpty(xmlType)) { // value is a string or object and we can assign TValue to value string strval = reader.ReadElementContentAsString(); value = (TValue) Convert.ChangeType(strval, typeof(TValue)); } else if (xmlType.StartsWith("___")) { while (reader.Read() && reader.NodeType != XmlNodeType.Element) { } Type type = ReflectionUtils.GetTypeFromName(xmlType.Substring(3)); //value = reader.ReadElementContentAs(type,null); XmlSerializer ser = new XmlSerializer(type); value = (TValue)ser.Deserialize(reader); } else value = (TValue)reader.ReadElementContentAs(XmlUtils.MapXmlTypeToType(xmlType), null); this.Add(name, value); } } } /// <summary> /// Serializes this dictionary to an XML string /// </summary> /// <returns>XML String or Null if it fails</returns> public string ToXml() { string xml = null; SerializationUtils.SerializeObject(this, out xml); return xml; } /// <summary> /// Deserializes from an XML string /// </summary> /// <param name="xml"></param> /// <returns>true or false</returns> public bool FromXml(string xml) { this.Clear(); // if xml string is empty we return an empty dictionary if (string.IsNullOrEmpty(xml)) return true; var result = SerializationUtils.DeSerializeObject(xml, this.GetType()) as PropertyBag<TValue>; if (result != null) { foreach (var item in result) { this.Add(item.Key, item.Value); } } else // null is a failure return false; return true; } /// <summary> /// Creates an instance of a propertybag from an Xml string /// </summary> /// <param name="xml"></param> /// <returns></returns> public static PropertyBag<TValue> CreateFromXml(string xml) { var bag = new PropertyBag<TValue>(); bag.FromXml(xml); return bag; } } } The code uses a couple of small helper classes SerializationUtils and XmlUtils for mapping Xml types to and from .NET, both of which are from the WestWind,Utilities project (which is the same project where PropertyBag lives) from the West Wind Web Toolkit. The code implements ReadXml and WriteXml for the IXmlSerializable implementation using old school XmlReaders and XmlWriters (because it's pretty simple stuff - no need for XLinq here). Then there are two helper methods .ToXml() and .FromXml() that basically allow your code to easily convert between XML and a PropertyBag object. In my code that's what I use to actually to persist to and from the entity XML property during .Load() and .Save() operations. It's sweet to be able to have a string key dictionary and then be able to turn around with 1 line of code to persist the whole thing to XML and back. Hopefully some of you will find this class as useful as I've found it. It's a simple solution to a common requirement in my applications and I've used the hell out of it in the  short time since I created it. Resources You can find the complete code for the two classes plus the helpers in the Subversion repository for Westwind.Utilities. You can grab the source files from there or download the whole project. You can also grab the full Westwind.Utilities assembly from NuGet and add it to your project if that's easier for you. PropertyBag Source Code SerializationUtils and XmlUtils Westwind.Utilities Assembly on NuGet (add from Visual Studio) © Rick Strahl, West Wind Technologies, 2005-2011Posted in .NET  CSharp   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Are there any empirical studies on the effect of different languages on software quality?

    - by jgre
    The proponents of functional programming languages assert that functional programming makes it easier to reason about code. Those in favor of statically typed languages say that their compilers catch enough errors to make up for the additional complexity of type systems. But everything I read on these topics is based on rational argument, not on empirical data. Are there any empirical studies on what effects the different categories of programming languages have on defect rates or other quality metrics? (The answers to this question seem to indicate that there are no such studies, at least not for the dynamic vs. static debate)

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  • Building dynamic OLAP data marts on-the-fly

    - by DrJohn
    At the forthcoming SQLBits conference, I will be presenting a session on how to dynamically build an OLAP data mart on-the-fly. This blog entry is intended to clarify exactly what I mean by an OLAP data mart, why you may need to build them on-the-fly and finally outline the steps needed to build them dynamically. In subsequent blog entries, I will present exactly how to implement some of the techniques involved. What is an OLAP data mart? In data warehousing parlance, a data mart is a subset of the overall corporate data provided to business users to meet specific business needs. Of course, the term does not specify the technology involved, so I coined the term "OLAP data mart" to identify a subset of data which is delivered in the form of an OLAP cube which may be accompanied by the relational database upon which it was built. To clarify, the relational database is specifically create and loaded with the subset of data and then the OLAP cube is built and processed to make the data available to the end-users via standard OLAP client tools. Why build OLAP data marts? Market research companies sell data to their clients to make money. To gain competitive advantage, market research providers like to "add value" to their data by providing systems that enhance analytics, thereby allowing clients to make best use of the data. As such, OLAP cubes have become a standard way of delivering added value to clients. They can be built on-the-fly to hold specific data sets and meet particular needs and then hosted on a secure intranet site for remote access, or shipped to clients' own infrastructure for hosting. Even better, they support a wide range of different tools for analytical purposes, including the ever popular Microsoft Excel. Extension Attributes: The Challenge One of the key challenges in building multiple OLAP data marts based on the same 'template' is handling extension attributes. These are attributes that meet the client's specific reporting needs, but do not form part of the standard template. Now clearly, these extension attributes have to come into the system via additional files and ultimately be added to relational tables so they can end up in the OLAP cube. However, processing these files and filling dynamically altered tables with SSIS is a challenge as SSIS packages tend to break as soon as the database schema changes. There are two approaches to this: (1) dynamically build an SSIS package in memory to match the new database schema using C#, or (2) have the extension attributes provided as name/value pairs so the file's schema does not change and can easily be loaded using SSIS. The problem with the first approach is the complexity of writing an awful lot of complex C# code. The problem of the second approach is that name/value pairs are useless to an OLAP cube; so they have to be pivoted back into a proper relational table somewhere in the data load process WITHOUT breaking SSIS. How this can be done will be part of future blog entry. What is involved in building an OLAP data mart? There are a great many steps involved in building OLAP data marts on-the-fly. The key point is that all the steps must be automated to allow for the production of multiple OLAP data marts per day (i.e. many thousands, each with its own specific data set and attributes). Now most of these steps have a great deal in common with standard data warehouse practices. The key difference is that the databases are all built to order. The only permanent database is the metadata database (shown in orange) which holds all the metadata needed to build everything else (i.e. client orders, configuration information, connection strings, client specific requirements and attributes etc.). The staging database (shown in red) has a short life: it is built, populated and then ripped down as soon as the OLAP Data Mart has been populated. In the diagram below, the OLAP data mart comprises the two blue components: the Data Mart which is a relational database and the OLAP Cube which is an OLAP database implemented using Microsoft Analysis Services (SSAS). The client may receive just the OLAP cube or both components together depending on their reporting requirements.  So, in broad terms the steps required to fulfil a client order are as follows: Step 1: Prepare metadata Create a set of database names unique to the client's order Modify all package connection strings to be used by SSIS to point to new databases and file locations. Step 2: Create relational databases Create the staging and data mart relational databases using dynamic SQL and set the database recovery mode to SIMPLE as we do not need the overhead of logging anything Execute SQL scripts to build all database objects (tables, views, functions and stored procedures) in the two databases Step 3: Load staging database Use SSIS to load all data files into the staging database in a parallel operation Load extension files containing name/value pairs. These will provide client-specific attributes in the OLAP cube. Step 4: Load data mart relational database Load the data from staging into the data mart relational database, again in parallel where possible Allocate surrogate keys and use SSIS to perform surrogate key lookup during the load of fact tables Step 5: Load extension tables & attributes Pivot the extension attributes from their native name/value pairs into proper relational tables Add the extension attributes to the views used by OLAP cube Step 6: Deploy & Process OLAP cube Deploy the OLAP database directly to the server using a C# script task in SSIS Modify the connection string used by the OLAP cube to point to the data mart relational database Modify the cube structure to add the extension attributes to both the data source view and the relevant dimensions Remove any standard attributes that not required Process the OLAP cube Step 7: Backup and drop databases Drop staging database as it is no longer required Backup data mart relational and OLAP database and ship these to the client's infrastructure Drop data mart relational and OLAP database from the build server Mark order complete Start processing the next order, ad infinitum. So my future blog posts and my forthcoming session at the SQLBits conference will all focus on some of the more interesting aspects of building OLAP data marts on-the-fly such as handling the load of extension attributes and how to dynamically alter the structure of an OLAP cube using C#.

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  • How does the GPL static vs. dynamic linking rule apply to interpreted languages?

    - by ekolis
    In my understanding, the GPL prohibits static linking from non-GPL code to GPL code, but permits dynamic linking from non-GPL code to GPL code. So which is it when the code in question is not linked at all because the code is written in an interpreted language (e.g. Perl)? It would seem to be too easy to exploit the rule if it was considered dynamic linking, but on the other hand, it would also seem to be impossible to legally reference GPL code from non-GPL code if it was considered static! Compiled languages at least have a distinction between static and dynamic linking, but when all "linking" is just running scripts, it's impossible to tell what the intent is without an explicit license! Or is my understanding of this issue incorrect, rendering the question moot? I've also heard of a "classpath exception" which involves dynamic linking; is that not part of the GPL but instead something that can be added on to it, so dynamic linking is only allowed when the license includes this exception?

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  • Turn-based tile game dynamic item/skill/command script files

    - by user1542
    I want to create a mechanism that could read text script, for example some kind of custom script such as ".skill" or ".item", which maybe contain some sort of simple script like .item Item.Name = "Strength Gauntlet"; Character.STR += 20; .. .skill Skill.Name = "Poison Attack"; Skill.Description = "Steal HP and inflict poison"; Player.HP += 200; Enemy.HP -= 200; Enemy.Status += Status.POISON; It may be different from this, but just want to give some idea of what I desire. However, I do not know how to dynamically parse these things and translate it into working script. For example, in battle scenerio, I should make my game read one of this ".skill" file and apply it to the current enemy, or the current player. How would I do this? Should I go for String parsing? It is like a script engine, but I prefer C# than creating new language, so how would I parse custom files into appropiate status commands? Another problem is, I have also created a command engine which would read String input and parse it into action such as "MOVE (1,2)" would move character to tile (1,2). Each command belong to separate class, and provide generic parsing method that should be implemented by hand. This is for the reason of custom number/type of arguments per each command. However, I think this is not well designed, because I desire it to automatically parse the parameters according to specify list of types. For example, MOVE command in "MOVE 1 2" would automatically parse the parameters into int, int and put it into X and Y. Now, this form can change, and we should be able to manually specify all type of formats. Any suggestion to this problem? Should I change from string parsing to some hardcode methods/classes?

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  • Scripting Part 1

    - by rbishop
    Dynamic Scripting is a large topic, so let me get a couple of things out of the way first. If you aren't familiar with JavaScript, I can suggest CodeAcademy's JavaScript series. There are also many other websites and books that cover JavaScript from every possible angle.The second thing we need to deal with is JavaScript as a programming language versus a JavaScript environment running in a web browser. Many books, tutorials, and websites completely blur these two together but they are in fact completely separate. What does this really mean in relation to DRM? Since DRM isn't a web browser, there are no document, window, history, screen, or location objects. There are no events like mousedown or click. Trying to call alert('hello!') in DRM will just cause an error. Those concepts are all related to an HTML document (web page) and are part of the Browser Object Model or Document Object Model. DRM has its own object model that exposes DRM-related objects. In practice, feel free to use those sorts of tutorials or practice within your browser; Many of the concepts are directly translatable to writing scripts in DRM. Just don't try to call document.getElementById in your property definition!I think learning by example tends to work the best, so let's try getting a list of all the unique property values for a given node and its children. var uniqueValues = {}; var childEnumerator = node.GetChildEnumerator(); while(childEnumerator.MoveNext()) { var propValue = childEnumerator.GetCurrent().PropValue("Custom.testpropstr1"); print(propValue); if(propValue != null && propValue != '' && !uniqueValues[propValue]) uniqueValues[propValue] = true; } var result = ''; for(var value in uniqueValues){ result += "Found value " + value + ","; } return result;  Now lets break this down piece by piece. var uniqueValues = {}; This declares a variable and initializes it as a new empty Object. You could also have written var uniqueValues = new Object(); Why use an object here? JavaScript objects can also function as a list of keys and we'll use that later to store each property value as a key on the object. var childEnumerator = node.GetChildEnumerator(); while(childEnumerator.MoveNext()) { This gets an enumerator for the node's children. The enumerator allows us to loop through the children one by one. If we wanted to get a filtered list of children, we would instead use ChildrenWith(). When we reach the end of the child list, the enumerator will return false for MoveNext() and that will stop the loop. var propValue = childEnumerator.GetCurrent().PropValue("Custom.testpropstr1"); print(propValue); if(propValue != null && propValue != '' && !uniqueValues[propValue]) uniqueValues[propValue] = true; } This gets the node the enumerator is currently pointing at, then calls PropValue() on it to get the value of a property. We then make sure the prop value isn't null or the empty string, then we make sure the value doesn't already exist as a key. Assuming it doesn't we add it as a key with a value (true in this case because it makes checking for an existing value faster when the value exists). A quick word on the print() function. When viewing the prop grid, running an export, or performing normal DRM operations it does nothing. If you have a lot of print() calls with complicated arguments it can slow your script down slightly, but otherwise has no effect. But when using the script editor, all the output of print() will be shown in the Warnings area. This gives you an extremely useful debugging tool to see what exactly a script is doing. var result = ''; for(var value in uniqueValues){ result += "Found value " + value + ","; } return result; Now we build a string by looping through all the keys in uniqueValues and adding that value to our string. The last step is to simply return the result. Hopefully this small example demonstrates some of the core Dynamic Scripting concepts. Next time, we can try checking for node references in other hierarchies to see if they are using duplicate property values.

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  • Is type safety worth the trade-offs?

    - by Prof Plum
    I began coding in in Python primarily where there is no type safety, then moved to C# and Java where there is. I found that I could work a bit more quickly and with less headaches in Python, but then again, my C# and Java apps are at much higher level of complexity so I have never given Python a true stress test I suppose. The Java and C# camps make it sound like without the type safety in place, most people would be running into all sorts of horrible bugs left an right and it would be more trouble than its worth. This is not a language comparison, so please do not address issues like compiled vs interpreted. Is type safety worth the hit to speed of development and flexibilty? WHY? to the people who wanted an example of the opinion that dynamic typing is faster: "Use a dynamically typed language during development. It gives you faster feedback, turn-around time, and development speed." - http://blog.jayway.com/2010/04/14/static-typing-is-the-root-of-all-evil/

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  • At what point should data be sent back to server?

    - by whamsicore
    A good example would be the stackexchange "rate" button. When a post is upvoted the arrow changes color immediately. However there is a grace period for one to edit one's vote decision (oops! voted by mistake?). Is the upvote action processed immediately or does is only process after a set time period, or when the user leaves the page? How exactly is this rating processed? What is the standard for handling dynamic page edits (e.g. stackexchange rating, facebook posts?)

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  • How to solve linear recurrences involving two functions?

    - by Aditya Bahuguna
    Actually I came across a question in Dynamic Programming where we need to find the number of ways to tile a 2 X N area with tiles of given dimensions.. Here is the problem statement Now after a bit of recurrence solving I came out with these. F(n) = F(n-1) + F(n-2) + 2G(n-1), and G(n) = G(n-1) + F(n-1) I know how to solve LR model where one function is there.For large N as is the case in the above problem we can do the matrix exponentiation and achieve O(k^3log(N)) time where k is the minimum number such that for all km F(n) does not depend on F(n-k). The method of solving linear recurrence with matrix exponentiation as it is given in that blog. Now for the LR involving two functions can anyone suggest an approach feasible enough for large N.

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  • Can there be an Environment that Reacts to Weather changes in-game?

    - by The415
    Just to be straightforward, I am completely new to many aspects of coding and am searching for different specs and guidelines to aid me on my journey to crafting a wonderful game in Epic Games' Unreal Engine 4. I had some recent thoughts about the possibility of creating an environment in a game that interacts with weather (Rain, Snow, Storms) Is it possible to make an environment that can simulate weather changes in a game? I wrote notes on this for weeks now. I was thinking that an increase on environments occlusion maps was necessary for creating the effect of rain on windows, as well as making a flowing liquid surface on windows that is only visible in rain. I was also considering the idea of additive bump-maps on meshes for snow, to simulate accumulation. Are these elements dynamic in Unreal 4? Can I implement them?

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  • Updated Business Activity Monitoring (BAM) Class

    - by Gary Barg
    We have just completed an extensive upgrade to the Business Activity Monitoring course, bringing it up to PS5 level and doing some major rework of content and topic flow. This should be a GREAT course for anyone needing to learn to use BAM effectively to analyze their SOA data. Details of the Course This course explains how to use Oracle BAM to monitor enterprise business activities across an enterprise in real time. You can measure your key performance indicators (KPIs), determine whether you are meeting service-level agreements (SLAs), and take corrective action in real time. Learn To: Create dashboards and alerts using a business-friendly, wizard-based design environment Monitor BPM and BPEL processes Configure drilling, driving, and time-based filtering Create alerts Build applications with a dynamic user interface Manage BAM users and roles In addition to learning Oracle BAM architecture, you learn how to perform administrative tasks related to Oracle BAM. You create and work with the different types of message sources that send data into Oracle BAM. You build interactive, real-time, actionable dashboards, and you configure alerts on abnormal conditions. You learn how to monitor both BPEL and BPM composite applications with Oracle BAM. Lastly, you create and use Oracle BAM data control to build applications with a dynamic user interface that changes based on real-time business events. Registration The Oracle University course page with more course details and registration information, is here. The next scheduled class: Date: 5-Dec-2012 Duration: 3 days Hours: 9:00 AM – 5:00 PM CT Location: Chicago, IL Class ID: 3325708

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  • Need to organize words based on their components, any other way aside from brute force?

    - by Lathan
    I'm not sure if this process has a name. I have some words (about 9,000). They are in Japanese, but I'll try to explain this using English words. I want to categorize the words by the components (in English, letters). A B C act bar play This should create: A: play B: bar C: act Now, 'a' appears in all 3 words, but I want to make sure that each category (letter) has at least word. Now, it would make sense to delete a word after it's used, but there are a few cases where 2 letters make up one word and that's each letter's only word--so I'd like to account for that somehow. Is there an approach for solving this aside from brute force? Dynamic programming perhaps? Even a name for this process (if it exists) would be great.

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  • ASp.Net Mvc 1.0 Dynamic Images Returned from Controller taking 154 seconds+ to display in IE8, firef

    - by julian guppy
    I have a curious problem with IE, IIS 6.0 dynamic PNG files and I am baffled as to how to fix.. Snippet from Helper (this returns the URL to the view for requesting the images from my Controller. string url = LinkBuilder.BuildUrlFromExpression(helper.ViewContext.RequestContext, helper.RouteCollection, c = c.FixHeight(ir.Filename, ir.AltText, "FFFFFF")); url = url.Replace("&", "&"); sb.Append(string.Format("<removed id=\"TheImage\" src=\"{0}\" alt=\"\" /", url)+Environment.NewLine); This produces a piece of html as follows:- img id="TheImage" src="/ImgText/FixHeight?sFile=Images%2FUser%2FJulianGuppy%2FMediums%2Fconservatory.jpg&backgroundColour=FFFFFF" alt="" / brackets missing because i cant post an image... even though I dont want to post an image I jsut want to post the markup... sigh Snippet from Controller ImgTextController /// <summary> /// This function fixes the height of the image /// </summary> /// <param name="sFile"></param> /// <param name="alternateText"></param> /// <param name="backgroundColour"></param> /// <returns></returns> [AcceptVerbs(HttpVerbs.Get)] public ActionResult FixHeight(string sFile, string alternateText, string backgroundColour) { #region File if (string.IsNullOrEmpty(sFile)) { return new ImgTextResult(); } // MVC specific change to prepend the new directory if (sFile.IndexOf("Content") == -1) { sFile = "~/Content/" + sFile; } // open the file System.Drawing.Image img; try { img = System.Drawing.Image.FromFile(Server.MapPath(sFile)); } catch { img = null; } // did we fail? if (img == null) { return new ImgTextResult(); } #endregion File #region Width // Sort out the width from the image passed to me Int32 nWidth = img.Width; #endregion Width #region Height Int32 nHeight = img.Height; #endregion Height // What is the ideal height given a width of 2100 this should be 1400. var nIdealHeight = (int)(nWidth / 1.40920096852); // So is the actual height of the image already greater than the ideal height? Int32 nSplit; if (nIdealHeight < nHeight) { // Yes, do nothing, well i need to return the iamge... nSplit = 0; } else { // rob wants to not show the white at the top or bottom, so if we were to crop the image how would be do it // 1. Calculate what the width should be If we dont adjust the heigt var newIdealWidth = (int)(nHeight * 1.40920096852); // 2. This newIdealWidth should be smaller than the existing width... so work out the split on that Int32 newSplit = (nWidth - newIdealWidth) / 2; // 3. Now recrop the image using 0-nHeight as the height (i.e. full height) // but crop the sides so that its the correct aspect ration var newRect = new Rectangle(newSplit, 0, newIdealWidth, nHeight); img = CropImage(img, newRect); nHeight = img.Height; nWidth = img.Width; nSplit = 0; } // No, so I want to place this image on a larger canvas and we do this by Creating a new image to be the size that we want System.Drawing.Image canvas = new Bitmap(nWidth, nIdealHeight, PixelFormat.Format24bppRgb); Graphics g = Graphics.FromImage(canvas); #region Color // Whilst we can set the background colour we shall default to white if (string.IsNullOrEmpty(backgroundColour)) { backgroundColour = "FFFFFF"; } Color bc = ColorTranslator.FromHtml("#" + backgroundColour); #endregion Color // Filling the background (which gives us our broder) Brush backgroundBrush = new SolidBrush(bc); g.FillRectangle(backgroundBrush, -1, -1, nWidth + 1, nIdealHeight + 1); // draw the image at the position var rect = new Rectangle(0, nSplit, nWidth, nHeight); g.DrawImage(img, rect); return new ImgTextResult { Image = canvas, ImageFormat = ImageFormat.Png }; } My ImgTextResult is a class that returns an Action result for me but embedding the image from a memory stream into the response.outputstream. snippet from my ImageResults /// <summary> /// Execute the result /// </summary> /// <param name="context"></param> public override void ExecuteResult(ControllerContext context) { // output context.HttpContext.Response.Clear(); context.HttpContext.Response.ContentType = "image/png"; try { var memStream = new MemoryStream(); Image.Save(memStream, ImageFormat.Png); context.HttpContext.Response.BinaryWrite(memStream.ToArray()); context.HttpContext.Response.Flush(); context.HttpContext.Response.Close(); memStream.Dispose(); Image.Dispose(); } catch (Exception ex) { string a = ex.Message; } } Now all of this works locally and lovely, and indeed all of this works on my production server BUT Only for Firefox, Safari, Chrome (and other browsers) IE has a fit and decides that it either wont display the image or it does display the image after approx 154seconds of waiting..... I have made sure my HTML is XHTML compliant, I have made sure I am getting no Routing errors or crashes in my event log on the server.... Now obviously I have been a muppet and have done something wrong... but what I cant fathom is why in development all works fine, and in production all non IE browsers also work fine, but IE 8 using IIS 6.0 production server is having some kind of problem in returning this PNG and I dont have an error to trace... so what I am looking for is guidance as to how I can debug this problem.

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  • Google Python Class Day 2 Part 1

    Google Python Class Day 2 Part 1 Google Python Class Day 2 Part 1: Regular Expressions. By Nick Parlante. Support materials and exercises: code.google.com From: GoogleDevelopers Views: 18 0 ratings Time: 42:00 More in Science & Technology

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  • Google Python Class Day 1 Part 3

    Google Python Class Day 1 Part 3 Google Python Class Day 1 Part 3: Dicts and Files. By Nick Parlante. Support materials and exercises: code.google.com From: GoogleDevelopers Views: 7 0 ratings Time: 28:59 More in Science & Technology

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  • Google Python Class Day 2 Part 2

    Google Python Class Day 2 Part 2 Google Python Class Day 2 Part 2: Utilities: OS and Commands. By Nick Parlante. Support materials and exercises: code.google.com From: GoogleDevelopers Views: 11 1 ratings Time: 20:20 More in Science & Technology

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