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• How to design a C / C++ library to be usable in many client languages?

  - by Brian Schimmel

  I'm planning to code a library that should be usable by a large number of people in on a wide spectrum of platforms. What do I have to consider to design it right? To make this questions more specific, there are four "subquestions" at the end. Choice of language Considering all the known requirements and details, I concluded that a library written in C or C++ was the way to go. I think the primary usage of my library will be in programs written in C, C++ and Java SE, but I can also think of reasons to use it from Java ME, PHP, .NET, Objective C, Python, Ruby, bash scrips, etc... Maybe I cannot target all of them, but if it's possible, I'll do it. Requirements It would be to much to describe the full purpose of my library here, but there are some aspects that might be important to this question: The library itself will start out small, but definitely will grow to enormous complexity, so it is not an option to maintain several versions in parallel. Most of the complexity will be hidden inside the library, though The library will construct an object graph that is used heavily inside. Some clients of the library will only be interested in specific attributes of specific objects, while other clients must traverse the object graph in some way Clients may change the objects, and the library must be notified thereof The library may change the objects, and the client must be notified thereof, if it already has a handle to that object The library must be multi-threaded, because it will maintain network connections to several other hosts While some requests to the library may be handled synchronously, many of them will take too long and must be processed in the background, and notify the client on success (or failure) Of course, answers are welcome no matter if they address my specific requirements, or if they answer the question in a general way that matters to a wider audience! My assumptions, so far So here are some of my assumptions and conclusions, which I gathered in the past months: Internally I can use whatever I want, e.g. C++ with operator overloading, multiple inheritance, template meta programming... as long as there is a portable compiler which handles it (think of gcc / g++) But my interface has to be a clean C interface that does not involve name mangling Also, I think my interface should only consist of functions, with basic/primitive data types (and maybe pointers) passed as parameters and return values If I use pointers, I think I should only use them to pass them back to the library, not to operate directly on the referenced memory For usage in a C++ application, I might also offer an object oriented interface (Which is also prone to name mangling, so the App must either use the same compiler, or include the library in source form) Is this also true for usage in C# ? For usage in Java SE / Java EE, the Java native interface (JNI) applies. I have some basic knowledge about it, but I should definitely double check it. Not all client languages handle multithreading well, so there should be a single thread talking to the client For usage on Java ME, there is no such thing as JNI, but I might go with Nested VM For usage in Bash scripts, there must be an executable with a command line interface For the other client languages, I have no idea For most client languages, it would be nice to have kind of an adapter interface written in that language. I think there are tools to automatically generate this for Java and some others For object oriented languages, it might be possible to create an object oriented adapter which hides the fact that the interface to the library is function based - but I don't know if its worth the effort Possible subquestions is this possible with manageable effort, or is it just too much portability? are there any good books / websites about this kind of design criteria? are any of my assumptions wrong? which open source libraries are worth studying to learn from their design / interface / souce? meta: This question is rather long, do you see any way to split it into several smaller ones? (If you reply to this, do it as a comment, not as an answer)

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• evaluating cost/benefits of using extension methods in C# => 3.0

  - by BillW

  Hi, In what circumstances (usage scenarios) would you choose to write an extension rather than sub-classing an object ? < full disclosure : I am not an MS employee; I do not know Mitsu Furota personally; I do know the author of the open-source Componax library mentioned here, but I have no business dealings with him whatsoever; I am not creating, or planning to create any commercial product using extensions : in sum : this post is from pure intellectal curiousity related to my trying to (continually) become aware of "best practices" I find the idea of extension methods "cool," and obviously you can do "far-out" things with them as in the many examples you can in Mitsu Furota's (MS) blog postslink text. A personal friend wrote the open-source Componax librarylink text, and there's some remarkable facilities in there; but he is in complete command of his small company with total control over code guidelines, and every line of code "passes through his hands." While this is speculation on my part : I think/guess other issues might come into play in a medium-to-large software team situation re use of Extensions. Looking at MS's guidelines at link text, you find : In general, you will probably be calling extension methods far more often than implementing your own. ... In general, we recommend that you implement extension methods sparingly and only when you have to. Whenever possible, client code that must extend an existing type should do so by creating a new type derived from the existing type. For more information, see Inheritance (C# Programming Guide). ... When the compiler encounters a method invocation, it first looks for a match in the type's instance methods. If no match is found, it will search for any extension methods that are defined for the type, and bind to the first extension method that it finds. And at Ms's link text : Extension methods present no specific security vulnerabilities. They can never be used to impersonate existing methods on a type, because all name collisions are resolved in favor of the instance or static method defined by the type itself. Extension methods cannot access any private data in the extended class. Factors that seem obvious to me would include : I assume you would not write an extension unless you expected it be used very generally and very frequently. On the other hand : couldn't you say the same thing about sub-classing ? Knowing we can compile them into a seperate dll, and add the compiled dll, and reference it, and then use the extensions : is "cool," but does that "balance out" the cost inherent in the compiler first having to check to see if instance methods are defined as described above. Or the cost, in case of a "name clash," of using the Static invocation methods to make sure your extension is invoked rather than the instance definition ? How frequent use of Extensions would affect run-time performance or memory use : I have no idea. So, I'd appreciate your thoughts, or knowing about how/when you do, or don't do, use Extensions, compared to sub-classing. thanks, Bill

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• Isn't it better to use a single try catch instead of tons of TryParsing and other error handling sometimes?

  - by Ryan Peschel

  I know people say it's bad to use exceptions for flow control and to only use exceptions for exceptional situations, but sometimes isn't it just cleaner and more elegant to wrap the entire block in a try-catch? For example, let's say I have a dialog window with a TextBox where the user can type input in to be parsed in a key-value sort of manner. This situation is not as contrived as you might think because I've inherited code that has to handle this exact situation (albeit not with farm animals). Consider this wall of code: class Animals { public int catA, catB; public float dogA, dogB; public int mouseA, mouseB, mouseC; public double cow; } class Program { static void Main(string[] args) { string input = "Sets all the farm animals CAT 3 5 DOG 21.3 5.23 MOUSE 1 0 1 COW 12.25"; string[] splitInput = input.Split(' '); string[] animals = { "CAT", "DOG", "MOUSE", "COW", "CHICKEN", "GOOSE", "HEN", "BUNNY" }; Animals animal = new Animals(); for (int i = 0; i < splitInput.Length; i++) { string token = splitInput[i]; if (animals.Contains(token)) { switch (token) { case "CAT": animal.catA = int.Parse(splitInput[i + 1]); animal.catB = int.Parse(splitInput[i + 2]); break; case "DOG": animal.dogA = float.Parse(splitInput[i + 1]); animal.dogB = float.Parse(splitInput[i + 2]); break; case "MOUSE": animal.mouseA = int.Parse(splitInput[i + 1]); animal.mouseB = int.Parse(splitInput[i + 2]); animal.mouseC = int.Parse(splitInput[i + 3]); break; case "COW": animal.cow = double.Parse(splitInput[i + 1]); break; } } } } } In actuality there are a lot more farm animals and more handling than that. A lot of things can go wrong though. The user could enter in the wrong number of parameters. The user can enter the input in an incorrect format. The user could specify numbers too large or too small for the data type to handle. All these different errors could be handled without exceptions through the use of TryParse, checking how many parameters the user tried to use for a specific animal, checking if the parameter is too large or too small for the data type (because TryParse just returns 0), but every one should result in the same thing: A MessageBox appearing telling the user that the inputted data is invalid and to fix it. My boss doesn't want different message boxes for different errors. So instead of doing all that, why not just wrap the block in a try-catch and in the catch statement just display that error message box and let the user try again? Maybe this isn't the best example but think of any other scenario where there would otherwise be tons of error handling that could be substituted for a single try-catch. Is that not the better solution?

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• What is this XML Parse Error?

  - by Jake

  I am using the following script to generate a RSS feed for my site: <?php class RSS { public function RSS() { $root = $_SERVER['DOCUMENT_ROOT']; require_once ("../connect.php"); } public function GetFeed() { return $this->getDetails() . $this->getItems(); } private function dbConnect() { DEFINE ('LINK', mysql_connect (DB_HOST, DB_USER, DB_PASSWORD)); } private function getDetails() { $detailsTable = "rss_feed_details"; $this->dbConnect($detailsTable); $query = "SELECT * FROM ". $detailsTable ." WHERE feed_category = ''"; $result = mysql_db_query (DB_NAME, $query, LINK); while($row = mysql_fetch_array($result)) { $details = '<?xml version="1.0" encoding="ISO-8859-1" ?> <rss version="2.0"> <channel> <title>'. $row['title'] .'</title> <link>'. $row['link'] .'</link> <description>'. $row['description'] .'</description> <language>'. $row['language'] .'</language> <image> <title>'. $row['image_title'] .'</title> <url>'. $row['image_url'] .'</url> <link>'. $row['image_link'] .'</link> <width>'. $row['image_width'] .'</width> <height>'. $row['image_height'] .'</height> </image>'; } return $details; } private function getItems() { $itemsTable = "rss_posts"; $this->dbConnect($itemsTable); $query = "SELECT * FROM ". $itemsTable ." ORDER BY id DESC"; $result = mysql_db_query (DB_NAME, $query, LINK); $items = ''; while($row = mysql_fetch_array($result)) { $items .= '<item> <title>'. $row["title"] .'</title> <link>'. $row["link"] .'</link> <description><![CDATA['.$row["readable_date"]."<br /><br />".$row["description"]."<br /><br />".']]></description> </item>'; } $items .= '</channel> </rss>'; return $items; } } ?> The baffling thing is, the script works perfectly fine on my localhost but gives the following error on my remote server: XML Parsing Error: junk after document element Location: http://mysite.com/rss/main/ Line Number 2, Column 1:<b>Parse error</b>: syntax error, unexpected T_STRING in <b>/home/studentw/public_html/rss/global-reach/rssClass.php</b> on line <b>1</b><br /> ^

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• Hibernate won't save into database

  - by Blitzkr1eg

  I mapped some classes to some tables with hibernate in java, i set hibernate to show SQL, it opens the session, it show that id does the SQL, it closes the session but there are no modifications to the database. Entity public class Profesor implements Comparable<Profesor> { private int id; private String nume; private String prenume; private int departament_id; private Set<Disciplina> listaDiscipline; //the teacher gives some courses} public class Disciplina implements Comparable<Disciplina>{ //the course class private int id; private String denumire; private String syllabus; private String schNotare; private Set<Lectie> lectii; private Set<Tema> listaTeme; private Set<Grup> listaGrupuri; // the course gets teached/assigmened to some groups of students private Set<Assignment> listAssignments;} Mapping <hibernate-mapping default-cascade="all"> <class name="model.Profesor" table="devgar_scoala.profesori"> <id name="id" column="id"> <generator class="increment"/> </id> <set name="listaDiscipline" table="devgar_scoala.`profesori-discipline`"> <key column="Profesori_id" /> <many-to-many class="model.Disciplina" column="Discipline_id" /> </set> <property name="nume" column="Nume" type="string" /> <property name="prenume" column="Prenume" type="string" /> <property name="departament_id" column="Departamente_id" type="integer" /> </class> <class name="model.Grup" table="devgar_scoala.grupe"> <id name="id" unsaved-value="0"> <generator class="increment"/> </id> <set name="listaStudenti" table="devgar_scoala.`studenti-grupe`"> <key column="Grupe_id" /> <many-to-many column="Studenti_nrMatricol" class="model.Student" /> </set> <property name="nume" column="Grupa" type="string"/> <property name="programStudiu" column="progStudii_id" type="integer" /> </class> <class name="model.Disciplina" table="devgar_scoala.discipline" > <id name="id" > <generator class="increment"/> </id> <property name="denumire" column="Denumire" type="string"/> <property name="syllabus" type="string" column="Syllabus"/> <property name="schNotare" type="string" column="SchemaNotare"/> <set name="listaGrupuri" table="devgar_scoala.`Discipline-Grupe`"> <key column="Discipline_id" /> <many-to-many column="Grupe_id" class="model.Grup" /> </set> <set name="lectii" table="devgar_scoala.lectii"> <key column="Discipline_id" not-null="true"/> <one-to-many class="model.Lectie" /> </set> </class> The only 'funny' thing is that the Profesor object gets loaded not with/by Hibernate but with manual classic SQL Java. Thats why i save the Profesor object like this p - the manually loaded Profesor object Profesor p2 = (Profesor) session.merge(p); session.saveOrUpdate(p2); //flush session of course After this i get in the Java console: Hibernate: insert into devgar_scoala.grupe (Grupa, progStudii_id, id) values (?, ?, ?) but when i look into the database there are no new rows in the table Grupe (the Groups table)

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• opening a fancybox from a drop down box and passing the selected value to it directly

  - by andy

  <select name="mySelectboxsituation_found" id="mySelectboxsituation_found"> <option value="100">Firecall</option> <option value="200">FireAlarm</option> <option value="300">FireAlarm2</option> <option value="400">FireAlarm4</option> </select> < a href="#" class="incidenttype" name="all" onClick="JavaScript:var dropdown=document.getElementById('mySelectboxsituation_found');this.href='main_situation_found.php?incident_maincateid='+dropdown.options[dropdown.selectedIndex].value;return true;"/>CLICK HERE < / a> function cleanUp(){ var subsituation_found1 = $("#fancybox- frame").contents().find('input:radio[name=incident_subcate]:checked').val(); } $(".incidenttype").fancybox({ 'width' : 900, 'height' : 600, 'autoScale': false, 'transitionIn': 'none', 'transitionOut': 'none', 'type': 'iframe', 'onCleanup': cleanUp ); }); clicking on "CLICK HERE" opens the fancybox and transfers the value selected in the drop down box. What I would like to do is open the fancy box when i change the value in the dropdown box...without having to click on the click here link.....i know it is posisble using something like _this....but i am not sure and am looking for some direction... ideally some thing like this ... <select name="mySelectboxsituation_found" id="mySelectboxsituation_found" onChange="JavaScript:var dropdown=document.getElementById('mySelectboxsituation_found');this.href='main_situation_found.php?incident_maincateid='+dropdown.options[dropdown.selectedIndex].value;return true;"> <option value="100">Firecall</option> <option value="200">FireAlarm</option> <option value="300">FireAlarm2</option> <option value="400">FireAlarm4</option> </select> does any have an idea how to do it.... I have also tried... function test_fan() { alert(document.getElementById('mySelectboxsituation_found').options[document.getElementById('mySelectboxsituation_found').selectedIndex].value); var dropval =document.getElementById('mySelectboxsituation_found').options[document.getElementById('mySelectboxsituation_found').selectedIndex].value; return dropval; } $(document).ready(function(){ $("#autostart").fancybox({ 'onStart':test_fan, 'width': 800, 'height': 700, 'type': 'iframe', href:'main_situation_found.php?incident_maincateid='+document.getElementById('mySelectboxsituation_found').options[document.getElementById('mySelectboxsituation_found').selectedIndex].value }); <a href="#" id="autostart" style="display:none"></a> <form><select id="mySelectboxsituation_found" onchange="$('#autostart').trigger('click');"> <option value="">select</option> <option value="100">option 1</option> <option value="200">trigger</option> <option value="300">option 3</option> <option value="400">option 4</option> </select> </form> the really funny that happens there is that .... on the alert id do get the value i selected so if i selected alert fancybox window 100 100 nothing shows up empty 200 200 100 300 300 200 400 400 300 the fancybox seems to me the the previously selected values and i am not sure why that is happening... thanks andy

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• How do I get jqGrid to work using ASP.NET + JSON on the backend?

  - by briandus

  Hi friends, ok, I'm back. I totally simplified my problem to just three simple fields and I'm still stuck on the same line using the addJSONData method. I've been stuck on this for days and no matter how I rework the ajax call, the json string, blah blah blah...I can NOT get this to work! I can't even get it to work as a function when adding one row of data manually. Can anyone PLEASE post a working sample of jqGrid that works with ASP.NET and JSON? Would you please include 2-3 fields (string, integer and date preferably?) I would be happy to see a working sample of jqGrid and just the manual addition of a JSON object using the addJSONData method. Thanks SO MUCH!! If I ever get this working, I will post a full code sample for all the other posting for help from ASP.NET, JSON users stuck on this as well. Again. THANKS!! tbl.addJSONData(objGridData); //err: tbl.addJSONData is not a function!! Here is what Firebug is showing when I receive this message: • objGridData Object total=1 page=1 records=5 rows=[5] ? Page "1" Records "5" Total "1" Rows [Object ID=1 PartnerID=BCN, Object ID=2 PartnerID=BCN, Object ID=3 PartnerID=BCN, 2 more... 0=Object 1=Object 2=Object 3=Object 4=Object] (index) 0 (prop) ID (value) 1 (prop) PartnerID (value) "BCN" (prop) DateTimeInserted (value) Thu May 29 2008 12:08:45 GMT-0700 (Pacific Daylight Time) * There are three more rows Here is the value of the variable tbl (value) 'Table.scroll' <TABLE cellspacing="0" cellpadding="0" border="0" style="width: 245px;" class="scroll grid_htable"><THEAD><TR><TH class="grid_sort grid_resize" style="width: 55px;"><SPAN> </SPAN><DIV id="jqgh_ID" style="cursor: pointer;">ID <IMG src="http://localhost/DNN5/js/jQuery/jqGrid-3.4.3/themes/sand/images/sort_desc.gif"/></DIV></TH><TH class="grid_resize" style="width: 90px;"><SPAN> </SPAN><DIV id="jqgh_PartnerID" style="cursor: pointer;">PartnerID </DIV></TH><TH class="grid_resize" style="width: 100px;"><SPAN> </SPAN><DIV id="jqgh_DateTimeInserted" style="cursor: pointer;">DateTimeInserted </DIV></TH></TR></THEAD></TABLE> Here is the complete function: $('table.scroll').jqGrid({ datatype: function(postdata) { mtype: "POST", $.ajax({ url: 'EDI.asmx/GetTestJSONString', type: "POST", contentType: "application/json; charset=utf-8", data: "{}", dataType: "text", //not json . let me try to parse success: function(msg, st) { if (st == "success") { var gridData; //strip of "d:" notation var result = JSON.parse(msg); for (var property in result) { gridData = result[property]; break; } var objGridData = eval("(" + gridData + ")"); //creates an object with visible data and structure var tbl = jQuery('table.scroll')[0]; alert(objGridData.rows[0].PartnerID); //displays the correct data //tbl.addJSONData(objGridData); //error received: addJSONData not a function //error received: addJSONData not a function (This uses eval as shown in the documentation) //tbl.addJSONData(eval("(" + objGridData + ")")); //the line below evaluates fine, creating an object and visible data and structure //var objGridData = eval("(" + gridData + ")"); //BUT, the same thing will not work here //tbl.addJSONData(eval("(" + gridData + ")")); //FIREBUG SHOWS THIS AS THE VALUE OF gridData: // "{"total":"1","page":"1","records":"5","rows":[{"ID":1,"PartnerID":"BCN","DateTimeInserted":new Date(1214412777787)},{"ID":2,"PartnerID":"BCN","DateTimeInserted":new Date(1212088125000)},{"ID":3,"PartnerID":"BCN","DateTimeInserted":new Date(1212088125547)},{"ID":4,"PartnerID":"EHG","DateTimeInserted":new Date(1235603192033)},{"ID":5,"PartnerID":"EMDEON","DateTimeInserted":new Date(1235603192000)}]}" } } }); }, jsonReader: { root: "rows", //arry containing actual data page: "page", //current page total: "total", //total pages for the query records: "records", //total number of records repeatitems: false, id: "ID" //index of the column with the PK in it }, colNames: [ 'ID', 'PartnerID', 'DateTimeInserted' ], colModel: [ { name: 'ID', index: 'ID', width: 55 }, { name: 'PartnerID', index: 'PartnerID', width: 90 }, { name: 'DateTimeInserted', index: 'DateTimeInserted', width: 100}], rowNum: 10, rowList: [10, 20, 30], imgpath: 'http://localhost/DNN5/js/jQuery/jqGrid-3.4.3/themes/sand/images', pager: jQuery('#pager'), sortname: 'ID', viewrecords: true, sortorder: "desc", caption: "TEST Example")};

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• Change default markers for directions on google maps

  - by Elaine Marley

  I'm a complete noob with google maps api and I started with a given script that I'm editing to what I need to do. In this case I have a map with some points in it that come from a database. They are like this (after I get the lat/lng from the database): var route1 = 'from: 37.496764,-5.913379 to: 37.392587,-6.00023'; var route2 = 'from: 37.392587,-6.00023 to: 37.376964,-5.990838'; routes = [route1, route2]; Then my script does the following: for(var j = 0; j < routes.length; j++) { callGDirections(j); document.getElementById("dbg").innerHTML += "called "+j+"<br>"; } And then the directions: function callGDirections(num) { directionsArray[num] = new GDirections(); GEvent.addListener(directionsArray[num], "load", function() { document.getElementById("dbg").innerHTML += "loaded "+num+"<br>"; var polyline = directionsArray[num].getPolyline(); polyline.setStrokeStyle({color:colors[num],weight:3,opacity: 0.7}); map.addOverlay(polyline); bounds.extend(polyline.getBounds().getSouthWest()); bounds.extend(polyline.getBounds().getNorthEast()); map.setCenter(bounds.getCenter(),map.getBoundsZoomLevel(bounds)); }); // === catch Directions errors === GEvent.addListener(directionsArray[num], "error", function() { var code = directionsArray[num].getStatus().code; var reason="Code "+code; if (reasons[code]) { reason = reasons[code] } alert("Failed to obtain directions, "+reason); }); directionsArray[num].load(routes[num], {getPolyline:true}); } The thing is, I want to change the A and B markers that I get from google on the map to the ones for each of the points that I'm using (each has it's particular icon in the database) but I don't know how to do this. Furthermore, what would be fantastic but I'm clueless if it's even possible is the following: when I get the directions I get something like this: (a) Street A directions (b) Street B And I want (a) Name of first point directions (b) Name of second point (also from database) I understand that my knowledge of the subject is very lacking and the question might be a bit vague, but I would appreciate any tip pointing me in the right direction. EDIT: Ok, I learned a lot from the google api with this problem but I'm still far from what I need. I learned how to hide the default markers doing this: // Hide the route markers when signaled. GEvent.addListener(directionsArray[num], "addoverlay", hideDirMarkers); // Not using the directions markers so hide them. function hideDirMarkers(){ var numMarkers = directionsArray[num].getNumGeocodes() for (var i = 0; i < numMarkers; i++) { var marker = directionsArray[num].getMarker(i); if (marker != null) marker.hide(); else alert("Marker is null"); } } And now when I create new markers doing this: var point = new GLatLng(lat,lng); var marker = createMarker(point,html); map.addOverlay(marker); They appear but they are not clickable (the popup with the html won't show)

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• Modern alternatives to Java

  - by Ralph

  I have been a Java developer for 14 years and have written an enterprise-level (~500 kloc) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. Are there other JVM-based languages that can be used for enterprise level development?

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• How do I launch a WPF app from command.com. I'm getting a FontCache error.

  - by jttraino

  I know this is not ideal, but my constraint is that I have a legacy application written in Clipper. I want to launch a new, WinForms/WPF application from inside the application (to ease transition). This legacy application written in Clipper launches using: SwpRunCmd("C:\MyApp\MyBat.bat",0) The batch file contains something like this command: C:\PROGRA~1\INTERN~1\iexplore "http://QASVR/MyApp/AppWin/MyCompany.MyApp.AppWin.application#MyCompany.MyApp.AppWin.application" It is launching a WinForms/WPF app that is we deploy via ClickOnce. Everything has been going well until we introduced WPF into the application. We were able to easily launch from the legacy application. Since we have introduced WPF, however, we have the following behavior. If we launch via the Clipper application first, we get an exception when launching the application. The error text is: The type initializer for 'System.Windows.FrameworkElement' threw an exception. at System.Windows.FrameworkElement..ctor() at System.Windows.Controls.Panel..ctor() at System.Windows.Controls.DockPanel..ctor() at System.Windows.Forms.Integration.AvalonAdapter..ctor(ElementHost hostControl) at System.Windows.Forms.Integration.ElementHost..ctor() at MyCompany.MyApp.AppWin.Main.InitializeComponent() at MyCompany.MyApp.AppWin.Main..ctor(String[] args) at MyCompany.MyApp.AppWin.Program.Main(String[] args) The type initializer for 'System.Windows.Documents.TextElement' threw an exception. at System.Windows.FrameworkElement..cctor() The type initializer for 'System.Windows.Media.FontFamily' threw an exception. at System.Windows.Media.FontFamily..ctor(String familyName) at System.Windows.SystemFonts.get_MessageFontFamily() at System.Windows.Documents.TextElement..cctor() The type initializer for 'MS.Internal.FontCache.Util' threw an exception. at MS.Internal.FontCache.Util.get_WindowsFontsUriObject() at System.Windows.Media.FontFamily.PreCreateDefaultFamilyCollection() at System.Windows.Media.FontFamily..cctor() Invalid URI: The format of the URI could not be determined. at System.Uri.CreateThis(String uri, Boolean dontEscape, UriKind uriKind) at System.Uri..ctor(String uriString, UriKind uriKind) at MS.Internal.FontCache.Util..cctor() If we launch the application via the URL (in IE) or via the icon on the desktop first, we do not get the exception and application launches as expected. The neat thing is that whatever we launch with first determines whether the app will launch at all. So, if we launch with legacy first, it breaks right away and we can't get the app to run even if we launch with the otherwise successful URL or icon. To get it to work, we have to logout and log back in and start it from the URL or icon. If we first use the URL or the icon, we have no problem launching from the legacy application from that point forward (until we logout and come back in). One other piece of information is that we are able to simulate the problem in the following fashion. If we enter a command prompt using "cmd.exe" and execute a statement to launch from a URL, we are successful. If, however, we enter a command prompt using "command.com" and we execute that same statement, we experience the breaking behavior. We assume it is because the legacy application in Clipper uses the equivalent of command.com to create the shell to spawn the other app. We have tried a bunch of hacks like having command.com run cmd.exe or psexec and then executing, but nothing seems to work. We have some ideas for workarounds (like making the app launch on startup so we force the successful launch from a URL, making all subsequent launches successful), but they all are sub-optimal even though we have a great deal of control over our workstations. To reduce the chance that this is related to permissions, we have given the launching account administrative rights (as well as non-administrative rights in case that made a difference). Any ideas would be greatly-appreciate. Like I said, we have some work arounds, but I would love to avoid them. Thanks!

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• Different setter behavior between DbContext and ObjectContext

  - by Paul

  (This is using EntityFramework 4.2 CTP) I haven't found any references to this on the web yet, although it's likely I'm using the wrong terminology while searching. There's also a very likely scenario where this is 100% expected behavior, just looking for confirmation and would rather not dig through the tt template (still new to this). Assuming I have a class with a boolean field called Active and I have one row that already has this value set to true. I have code that executes to set said field to True regardless of it's existing value. If I use DbContext to update the value to True no update is made. If I use ObjectContext to update the value an update is made regardless of the existing value. This is happening in the exact same EDMX, all I did was change the code generation template from DbContext to EntityObject. Update: Ok, found the confirmation I was looking for...consider this a dupe...next time I'll do MOAR SEARCHING! Entity Framework: Cancel a property change if no change in value ** Update 2: ** Problem: the default tt template wraps the "if (this != value)" in the setter with "if (iskey), so only primarykey fields receive this logic. Solution: it's not the most graceful thing, but I removed this check...we'll see how it pans out in real usage. I included the entire tt template, my changes are denoted with "**"... //////// //////// Write SimpleType Properties. //////// private void WriteSimpleTypeProperty(EdmProperty simpleProperty, CodeGenerationTools code) { MetadataTools ef = new MetadataTools(this); #> /// <summary> /// <#=SummaryComment(simpleProperty)#> /// </summary><#=LongDescriptionCommentElement(simpleProperty, 1)#> [EdmScalarPropertyAttribute(EntityKeyProperty= <#=code.CreateLiteral(ef.IsKey(simpleProperty))#>, IsNullable=<#=code.CreateLiteral(ef.IsNullable(simpleProperty))#>)] [DataMemberAttribute()] <#=code.SpaceAfter(NewModifier(simpleProperty))#><#=Accessibility.ForProperty(simpleProperty)#> <#=MultiSchemaEscape(simpleProperty.TypeUsage, code)#> <#=code.Escape(simpleProperty)#> { <#=code.SpaceAfter(Accessibility.ForGetter(simpleProperty))#>get { <#+ if (ef.ClrType(simpleProperty.TypeUsage) == typeof(byte[])) { #> return StructuralObject.GetValidValue(<#=code.FieldName(simpleProperty)#>); <#+ } else { #> return <#=code.FieldName(simpleProperty)#>; <#+ } #> } <#=code.SpaceAfter(Accessibility.ForSetter((simpleProperty)))#>set { <#+ **//if (ef.IsKey(simpleProperty)) **//{ if (ef.ClrType(simpleProperty.TypeUsage) == typeof(byte[])) { #> if (!StructuralObject.BinaryEquals(<#=code.FieldName(simpleProperty)#>, value)) <#+ } else { #> if (<#=code.FieldName(simpleProperty)#> != value) <#+ } #> { <#+ PushIndent(CodeRegion.GetIndent(1)); **//} #> <#=ChangingMethodName(simpleProperty)#>(value); ReportPropertyChanging("<#=simpleProperty.Name#>"); <#=code.FieldName(simpleProperty)#> = <#=CastToEnumType(simpleProperty.TypeUsage, code)#>StructuralObject.SetValidValue(<#=CastToUnderlyingType(simpleProperty.TypeUsage, code)#>value<#=OptionalNullableParameterForSetValidValue(simpleProperty, code)#>, "<#=simpleProperty.Name#>"); ReportPropertyChanged("<#=simpleProperty.Name#>"); <#=ChangedMethodName(simpleProperty)#>(); <#+ //if (ef.IsKey(simpleProperty)) //{ PopIndent(); #> } <#+ //} #> } }

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• How can I display the clicked products by user on a list in another view?

  - by Avar

  I am using MVC3 Viewmodel pattern with Entity Framework on my webbapplication. My Index View is list of products with image, price and description and etc. Products with the information I mentioned above is in div boxes with a button that says "buy". I will be working with 2 views one that is the Index View that will display all the products and the other view that will display the products that got clicked by the buy button. What I am trying to achieve is when a user click on buy button the products should get stored in the other view that is cart view and be displayed. I have problems on how to begin the coding for that part. The index View with products is done and now its the buy button function left to do but I have no idea how to start. This is my IndexController: private readonly HomeRepository repository = new HomeRepository(); public ActionResult Index() { var Productlist = repository.GetAllProducts(); var model = new HomeIndexViewModel() { Productlist = new List<ProductsViewModel>() }; foreach (var Product in Productlist) { FillProductToModel(model, Product); } return View(model); } private void FillProductToModel(HomeIndexViewModel model, ProductImages productimage) { var productViewModel = new ProductsViewModel { Description = productimage.Products.Description, ProductId = productimage.Products.Id, price = productimage.Products.Price, Name = productimage.Products.Name, Image = productimage.ImageUrl, }; model.Productlist.Add(productViewModel); } In my ActionResult Index I am using my repository to get the products and then I am binding the data from the products to my ViewModel so I can use the ViewModel inside my view. Thats how I am displaying all the products in my View. This is my Index View: @model Avan.ViewModels.HomeIndexViewModel @foreach (var item in Model.Productlist) { <div id="productholder@(item.ProductId)" class="productholder"> <img src="@Html.DisplayFor(modelItem => item.Image)" alt="" /> <div class="productinfo"> <h2>@Html.DisplayFor(modelItem => item.Name)</h2> <p>@Html.DisplayFor(modelItem => item.Description)</p> @Html.Hidden("ProductId", item.ProductId, new { @id = "ProductId" }) </div> <div class="productprice"> <h2>@Html.DisplayFor(modelItem => item.price)</h2> <input type="button" value="Läs mer" class="button" id="button@(item.ProductId)"> @Html.ActionLink("x", "Cart", new { id = item.ProductId }) // <- temp its going to be a button </div> </div> } Since I can get the product ID per product I can use the ID in my controller to get the data from the database. But I still I have no idea how I can do that so when somebody click on the buy button I store the ID where? and how do I use it so I can achieve what I want to do? Right now I have been trying to do following thing in my IndexController: public ActionResult cart(int id) { var SelectedProducts = repository.GetProductByID(id); return View(); } What I did here is that I get the product by the id. So when someone press on the temp "x" Actionlink I will recieve the product. All I know is that something like that is needed to achieve what im trying to do but after that I have no idea what to do and in what kind of structure I should do it. Any kind of help is appreciated alot! Short Scenario: looking at the Index I see 5 products, I choose to buy 3 products so I click on three "Buy" buttons. Now I click on the "Cart" that is located on the nav menu. New View pops up and I see the three products that I clicked to buy.

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• Is there a way to delay compilation of a stored procedure's execution plan?

  - by Ian Henry

  (At first glance this may look like a duplicate of http://stackoverflow.com/questions/421275 or http://stackoverflow.com/questions/414336, but my actual question is a bit different) Alright, this one's had me stumped for a few hours. My example here is ridiculously abstracted, so I doubt it will be possible to recreate locally, but it provides context for my question (Also, I'm running SQL Server 2005). I have a stored procedure with basically two steps, constructing a temp table, populating it with very few rows, and then querying a very large table joining against that temp table. It has multiple parameters, but the most relevant is a datetime "@MinDate." Essentially: create table #smallTable (ID int) insert into #smallTable select (a very small number of rows from some other table) select * from aGiantTable inner join #smallTable on #smallTable.ID = aGiantTable.ID inner join anotherTable on anotherTable.GiantID = aGiantTable.ID where aGiantTable.SomeDateField > @MinDate If I just execute this as a normal query, by declaring @MinDate as a local variable and running that, it produces an optimal execution plan that executes very quickly (first joins on #smallTable and then only considers a very small subset of rows from aGiantTable while doing other operations). It seems to realize that #smallTable is tiny, so it would be efficient to start with it. This is good. However, if I make that a stored procedure with @MinDate as a parameter, it produces a completely inefficient execution plan. (I am recompiling it each time, so it's not a bad cached plan...at least, I sure hope it's not) But here's where it gets weird. If I change the proc to the following: declare @LocalMinDate datetime set @LocalMinDate = @MinDate --where @MinDate is still a parameter create table #smallTable (ID int) insert into #smallTable select (a very small number of rows from some other table) select * from aGiantTable inner join #smallTable on #smallTable.ID = aGiantTable.ID inner join anotherTable on anotherTable.GiantID = aGiantTable.ID where aGiantTable.SomeDateField > @LocalMinDate Then it gives me the efficient plan! So my theory is this: when executing as a plain query (not as a stored procedure), it waits to construct the execution plan for the expensive query until the last minute, so the query optimizer knows that #smallTable is small and uses that information to give the efficient plan. But when executing as a stored procedure, it creates the entire execution plan at once, thus it can't use this bit of information to optimize the plan. But why does using the locally declared variables change this? Why does that delay the creation of the execution plan? Is that actually what's happening? If so, is there a way to force delayed compilation (if that indeed is what's going on here) even when not using local variables in this way? More generally, does anyone have sources on when the execution plan is created for each step of a stored procedure? Googling hasn't provided any helpful information, but I don't think I'm looking for the right thing. Or is my theory just completely unfounded? Edit: Since posting, I've learned of parameter sniffing, and I assume this is what's causing the execution plan to compile prematurely (unless stored procedures indeed compile all at once), so my question remains -- can you force the delay? Or disable the sniffing entirely? The question is academic, since I can force a more efficient plan by replacing the select * from aGiantTable with select * from (select * from aGiantTable where ID in (select ID from #smallTable)) as aGiantTable Or just sucking it up and masking the parameters, but still, this inconsistency has me pretty curious.

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• Use component id in Castle Windsor generic object configuration

  - by ChoccyButton

  2 questions in one, but very much related. Is it possible with Castle Windsor to resolve a configuration entry such as - Assembly.Namespace.Object1`2[[${ComponentId1}],[${ComponentId2}]], Assembly Where ComponentId1 and ComponentId2 are defined as components. Castle Windsor doesn't seem to be resolving the ComponentId, it is just looking for ComponentId1 in the Castle.Windsor assembly. The second question comes in to play if you can't do the first question. If you have to use a full assembly reference instead of a ComponentId, how can you pass any parameters to the object being created? eg to set ComponentId1.Field1 = "blah", or pass something to the constructor of ComponentId1 Hope that makes sense Update - Following the request for code I've knocked together the following - Objects public class Wrapper<T, T1> where T : ICollector where T1:IProcessor { private T _collector; private T1 _processor; public Wrapper(T collector, T1 processor) { _collector = collector; _processor = processor; } public void GetData() { _collector.CollectData(); _processor.ProcessData(); } } public class Collector1 : ICollector { public void CollectData() { Console.WriteLine("Collecting data from Collector1 ..."); } } public class Processor1 : IProcessor { public void ProcessData() { Console.WriteLine("Processing data from Processor1 ..."); } } repeated so 3 of each type of object in the example Config <components> <component id="Collector1" service="CastleWindsorPlay.ICollector, CastleWindsorPlay" type="CastleWindsorPlay.Collector1, CastleWindsorPlay"/> <component id="Collector2" service="CastleWindsorPlay.ICollector, CastleWindsorPlay" type="CastleWindsorPlay.Collector2, CastleWindsorPlay"/> <component id="Collector3" service="CastleWindsorPlay.ICollector, CastleWindsorPlay" type="CastleWindsorPlay.Collector3, CastleWindsorPlay"/> <component id="Processor1" service="CastleWindsorPlay.IProcessor, CastleWindsorPlay" type="CastleWindsorPlay.Processor1, CastleWindsorPlay"/> <component id="Processor2" service="CastleWindsorPlay.IProcessor, CastleWindsorPlay" type="CastleWindsorPlay.Processor2, CastleWindsorPlay"/> <component id="Processor3" service="CastleWindsorPlay.IProcessor, CastleWindsorPlay" type="CastleWindsorPlay.Processor3, CastleWindsorPlay"/> <component id="Wrapper1" type="CastleWindsorPlay.Wrapper`2[[CastleWindsorPlay.Collector1, CastleWindsorPlay],[CastleWindsorPlay.Processor3, CastleWindsorPlay]], CastleWindsorPlay" /> </components> Instantiation var wrapper = (Wrapper<ICollector, IProcessor>) container.Resolve("Wrapper1"); wrapper.GetData(); This brief example errors with this error message though - Can't create component 'Wrapper1' as it has dependencies to be satisfied. Wrapper1 is waiting for the following dependencies: Services: - CastleWindsorPlay.Collector1 which was not registered. - CastleWindsorPlay.Processor3 which was not registered. The curious part about this is that I can get it to resolve Collector1 and Processor3 individually before the call to the wrapper, but the wrapper still can't see them. This is a basic example, the next thing I'd like to be able to do is when instantiating the Wrapper, set a property on the collector and/or processor. So it could be something like Collector.Id = 10, but set in the config where the wrapper is defined. Setting against the Collector component definition wouldn't work as I'd want to be able to instantiate multiple copies of each Collector, using different Id's Update 2 What I'm actually trying to do is have - <components> <component id="Wrapper1" type="CastleWindsorPlay.Wrapper`2[${Collector1}(id=1)],[${Processor3}]], CastleWindsorPlay" /> <component id="Wrapper2" type="CastleWindsorPlay.Wrapper`2[${Collector1}(id=3)],[${Processor3}]], CastleWindsorPlay" /> </components> Then have another object defined as <component id="Manager" type="CastleWindsorPlay.Manager,CastleWindsorPlay"> <parameters> <wrappers> <array> <item>${Wrapper1}</item> <item>${Wrapper2}</item> </array> </wrappers> </parameters> Then finally in code just be able to call - var manager = (Manager)container.Resolve("Manager"); This should return the manager object, with an array of wrappers populated and the wrappers configured with the correct Collector and Convertor. I know there are errors in the Castle config here, that's why I'm asking the question, I don't know how to set the config up to do what I'm after, or even if it's possible to do it in Castle Windsor

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• Android app hanging, sometimes until Force Close / Wait dialog appears

  - by fredley

  I'm making an app that records uncompressed (wav format) audio. I'm using this class to actually record the audio. Currently, my application records fine (I can play the file), however when I click the button to stop the recording, the app hangs for 10 seconds or so, with no log output or any signs of life. Finally it comes round, dumps a load of errors into the log, updates the UI etc. I'm using AsyncTasks to try and avoid this kind of thing but it's not working. Here's my code: //Called on clicks of the record button. rar is the instance of RehearsalAudioRecorder private OnClickListener RecordListener = new OnClickListener(){ @Override public void onClick(View v) { Log.d("Record","Click"); if (recording){ new stopRecordingTask().execute(rar,null,null); startStop.setText("Record"); statusBar.setText("Recording Finished, ready to Encode"); }else{ recording = true; new startRecordingTask().execute(rar,null,null); startStop.setText("Stop"); statusBar.setText("Recording Started"); } } }; private class startRecordingTask extends AsyncTask<RehearsalAudioRecorder,Void,Void>{ @Override protected Void doInBackground(RehearsalAudioRecorder... rs) { RehearsalAudioRecorder r = rs[0]; r.setOutputFile("/sdcard/rarOut.wav"); r.prepare(); r.start(); return null; } } private class stopRecordingTask extends AsyncTask<RehearsalAudioRecorder,Void,Void>{ @Override protected Void doInBackground(RehearsalAudioRecorder... rs) { RehearsalAudioRecorder r = rs[0]; r.stop(); r.reset(); return null; } } In Logcat, I always get output like this, which has me stumped. I have no idea what's causing it (I'm logging the RehearsalAudioRecorder class, and it's being started/stopped correctly by the button clicks. This output occurs after the log output for the button click and correct stop() method call) 12-19 11:59:11.172: ERROR/AudioRecord-JNI(22662): Unable to retrieve AudioRecord object, can't record 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): Error occured in updateListener, recording is aborted 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): stop() called on illegal state: STOPPED 12-19 11:59:11.172: ERROR/AudioRecord-JNI(22662): Unable to retrieve AudioRecord object, can't record 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): Error occured in updateListener, recording is aborted 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): stop() called on illegal state: ERROR 12-19 11:59:11.172: ERROR/AudioRecord-JNI(22662): Unable to retrieve AudioRecord object, can't record 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): Error occured in updateListener, recording is aborted 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): stop() called on illegal state: ERROR ... 10 or more times I've been fiddling with this all day and I'm not getting anywhere, any input would be greatly appreciated. Update I've replace the AsyncTasks with Threads, still doesn't work, the app completely hangs when I click record, despite the fact the Log indicates there's nothing going on in the main thread. Still completely stumped.

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• Passing a list of files to javac

  - by Robert Menteer

  How can I get the javac task to use an existing fileset? In my build.xml I have created several filesets to be used in multiple places throughout build file. Here is how they have been defined: <fileset dir = "${src}" id = "java.source.all"> <include name = "**/*.java" /> </fileset> <fileset dir = "${src}" id = "java.source.examples"> <include name = "**/Examples/**/*.java" /> </fileset> <fileset dir = "${src}" id = "java.source.tests"> <include name = "**/Tests/*.java" /> </fileset> <fileset dir = "${src}" id = "java.source.project"> <include name = "**/*.java" /> <exclude name = "**/Examples/**/*.java" /> <exclude name = "**/Tests/**/*.java" /> </fileset> I have also used macrodef to compile the java files so the javac task does not need to be repeated multiple times. The macro looks like this: <macrodef name="compile"> <attribute name="sourceref"/> <sequential> <javac srcdir = "${src}" destdir = "${build}" classpathref = "classpath" includeantruntime = "no" debug = "${debug}"> <filelist dir="." files="@{sourceref}" /> <-- email is about this </javac> </sequential> What I'm trying to do is compile only the classes that are needed for specific targets not all the targets in the source tree. And do so without having to specify the files every time. Here are how the targets are defined: <target name = "compile-examples" depends = "init"> <compile sourceref = "${toString:java.source.examples}" /> </target> <target name = "compile-project" depends = "init"> <compile sourceref = "${toString:java.source.project}" /> </target> <target name = "compile-tests" depends = "init"> <compile sourceref = "${toString:java.source.tests}" /> </target> As you can see each target specifies the java files to be compiled as a simi-colon separated list of absolute file names. The only problem with this is that javac does not support filelist. It also does not support fileset, path or pathset. I've tried using but it treats the list as a single file name. Another thing I tried is sending the reference directly (not using toString) and using but include does not have a ref attribute. SO THE QUESTION IS: How do you get the javac task to use a reference to a fileset that was defined in another part of the build file? I'm not interested in solutions that cause me to have multiple javac tasks. Completely re-writting the macro is acceptable. Changes to the targets are also acceptable provided redundant code between targets is kept to a minimum. p.s. Another problem is that fileset wants a comma separated list. I've only done a brief search for a way to convert semi-colons to commas and haven't found a way to do that. p.p.s. Sorry for the yelling but some people are too quick to post responses that don't address the subject.

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• Decentralized synchronized secure data storage

  - by Alberich

  Introduction Hi, I am going to ask a question which seems utopic for me, but I need to know if there is a way to achieve what I need. And if not, I need to know why not. The idea Suppose I have a database structure, in MySql. I want to create some solution to allow anyone (no matter who, no matter where) to have a synchronized copy (updated clone) of this database (with its content) Well, and it is not going to be just one synchronized copy, it could (and should) be a multiple replication (supposing the basic, this means, for example, ten copies all over the world) And, the most important thing: It must be secure. By secure I mean only real-accepted transactions will be synchronized with all the others (no matter how many) database copies/clones. Note: Since it would be quite difficult to make the synchronization in real-time, I will design everything to make this feature dispensable. So it is not required. My auto-suggestion This is how I am thinking to manage it: Time identifiers and Updates checking: Every action (insert, update, delete...) will be stored as the action instruction itself, associated to the time identifier. [I think better than a DATETIME field, it'll be an INT one, with the number of miliseconds passed from 1st january 2013 on, for example]. So each copy is going to ask to the "neighbour copy" for new actions done since last update, and execute them after checking they are allowed. Problem 1: the "neighbour copy" could be outdated too. Solution 1: do not ask just one neighbour, create a random list with some of the copies/clones and ask them for news (I could avoid the list and ask ALL the clones for updates, but this will be inefficient if clones number ascends too much). Problem 2: Real-time global synchronization is not active. What if... Someone at CLONE_ENTERPRISING inserts a row into TABLE. ... this row goes to every clone ... Someone at CLONE_FIXEMALL deletes this row. ... and at the same time, somewhere in an outdated clone ... Someone at CLONE_DROPOUT edits this row (now inexistent at the other clones) Solution 2: easy stuff, force a GLOBAL synchronization before doing any new "depending-on-third-data action" (edit, for example). This global synch. will be unnecessary when making an INSERT, for instance. Note: Well, someone could have some fun, and make the same insert in two clones... since they're not getting updated in real-time, this row will exist twice. But, it's the same as when we have one single database, in some needed cases we check if there is an existing same-row before doing the final action. Not a problem. Problem 3: It is possible to edit the code and do not filter actions, so someone could spread instructions to delete everything, or just make some trolling activity. This is not a problem, since good clones will always be somewhere. Those who got bad won't interest anymore. I really appreciate if you read. I know this is not the perfect solution, it has possibly hundred of holes, but it is my basic start. I will now appreciate anything you can teach me now. Thanks a lot. PS.: It could be that all this I am trying already exists and has its own name. Sorry for asking then (I'd anyway thank this name, if it exists)

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• Make c# matrix code faster

  - by Wam

  Hi all, Working on some matrix code, I'm concerned of performance issues. here's how it works : I've a IMatrix abstract class (with all matrices operations etc), implemented by a ColumnMatrix class. abstract class IMatrix { public int Rows {get;set;} public int Columns {get;set;} public abstract float At(int row, int column); } class ColumnMatrix : IMatrix { private data[]; public override float At(int row, int column) { return data[row + columns * this.Rows]; } } This class is used a lot across my application, but I'm concerned with performance issues. Testing only read for a 2000000x15 matrix against a jagged array of the same size, I get 1359ms for array access agains 9234ms for matrix access : public void TestAccess() { int iterations = 10; int rows = 2000000; int columns = 15; ColumnMatrix matrix = new ColumnMatrix(rows, columns); for (int i = 0; i < rows; i++) for (int j = 0; j < columns; j++) matrix[i, j] = i + j; float[][] equivalentArray = matrix.ToRowsArray(); TimeSpan totalMatrix = new TimeSpan(0); TimeSpan totalArray = new TimeSpan(0); float total = 0f; for (int iteration = 0; iteration < iterations; iteration++) { total = 0f; DateTime start = DateTime.Now; for (int i = 0; i < rows; i++) for (int j = 0; j < columns; j++) total = matrix.At(i, j); totalMatrix += (DateTime.Now - start); total += 1f; //Ensure total is read at least once. total = total > 0 ? 0f : 0f; start = DateTime.Now; for (int i = 0; i < rows; i++) for (int j = 0; j < columns; j++) total = equivalentArray[i][j]; totalArray += (DateTime.Now - start); } if (total < 0f) logger.Info("Nothing here, just make sure we read total at least once."); logger.InfoFormat("Average time for a {0}x{1} access, matrix : {2}ms", rows, columns, totalMatrix.TotalMilliseconds); logger.InfoFormat("Average time for a {0}x{1} access, array : {2}ms", rows, columns, totalArray.TotalMilliseconds); Assert.IsTrue(true); } So my question : how can I make this thing faster ? Is there any way I can make my ColumnMatrix.At faster ? Cheers !

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• What's wrong in this C program..? [closed]

  - by AGeek

  struct bucket { int nStrings; //No. of Strings in a Bucket. char strings[MAXSTRINGS][MAXWORDLENGTH]; // A bucket row can contain maximum 9 strings of max string length 10. };//buck[TOTBUCKETS]; void lexSorting(char array[][10], int lenArray, int symb) //symb - symbol, sorting based on character symbols. { int i, j; int bucketNo; int tBuckNStrings; bucket buck[TOTBUCKETS]; for(i=0; i<lenArray; i++) { bucketNo = array[i][symb] - 'a'; // Find Bucket No. in which the string is to be placed. tBuckNStrings = buck[bucketNo].nStrings; // temp variable for storing nStrings var in bucket structure. strcpy(buck[bucketNo].strings[tBuckNStrings],array[i]); // Store the string in its bucket. buck[bucketNo].nStrings = ++tBuckNStrings; //Increment the nStrings value of the bucket. } // lexSorting(array, lenArray, ++symb); printf("****** %d ******\n", symb); for(i=0; i<TOTBUCKETS; i++) { printf("%c = ", i+'a'); for(j=0; j<buck[i].nStrings; j++) printf("%s ",buck[i].strings[j]); printf("\n"); } } int main() { char array[][10] = {"able","aback","a","abet","acid","yawn","yard","yarn","year","yoke"}; int lenArray = 10; int i; printf("Strings: "); for(i=0; i<lenArray; i++) printf("%s ",array[i]); printf("\n"); lexSorting(array, lenArray, 0); } Well here is the complete code, that I am trying. since its been a long time since i have touched upon C programming, so somewhere i am making mistake in structure declaration. The problem goes here:- 1) I have declared a structure above and its object as array(buck[]). 2) Now when I declare this object array along with the structure, it works fine.. I have commented this thing right now. 3) But when I declare this object array inside the function.. because ultimately i have to declare inside function( as i need to build a recursive program, where objects will be created in very recursive call) then the program is throwing segmentation fault. Expected Output > [others@centos htdocs]$ ./a.out > Strings: able aback a abet acid yawn > yard yarn year yoke > ****** 0 ****** > a = able aback a abet acid > b = > c > . > . > y = yawn yard yarnyear yoke > z = Actual Output [others@centos htdocs]$ ./a.out Strings: able aback a abet acid yawn yard yarn year yoke Segmentation fault I have no idea, what difference I made in this. Kindly help. Thanks.

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• Change ListView background - strage behaviour

  - by Beasly

  Hi again, I have a problem with changing the background of a view in a ListView. What I need: Change the background image of a row onClick() What actually happens: The background gets changed (selected) after pressing e.g. the first entry. But after scrolling down the 8th entry is selected too. Scroll back to the top the first isn't selected anymore. The second entry is selected now. Continue scrolling and it continues jumping... What i'm dong in the Code: I have channels, and onClick() I toggle an attribute of channel boolean selected and then I change the background. I'm doing this only onClick() thats why I don't get why it's actuelly happening on other entries too. One thing I notices is: It seems to be only the "drawing"-part because the item which get selected "by it self" has still the selected value on false I think it seems to have something to do with the reuse of the views in the custom ListAdapters getView(...) Code of onClick() in ListActivity: @Override protected ViewHolder createHolder(View v) { // createHolder will be called only as long, as the ListView is not // filled TextView title = (TextView) v .findViewById(R.id.tv_title_channel_list_adapter); TextView content = (TextView) v .findViewById(R.id.tv_content_channel_list_adapter); ImageView icon = (ImageView) v .findViewById(R.id.icon_channel_list_adapter); if (title == null || content == null || icon == null) { Log.e("ERROR on findViewById", "Couldn't find Title, Content or Icon"); } ViewHolder mvh = new MyViewHolder(title, content, icon); // We make the views become clickable // so, it is not necessary to use the android:clickable attribute in // XML v.setOnClickListener(new ChannelListAdapter.OnClickListener(mvh) { public void onClick(View v, ViewHolder viewHolder) { // we toggle the enabled state and also switch the the // background MyViewHolder mvh = (MyViewHolder) viewHolder; Channel ch = (Channel) mvh.data; ch.setSelected(!ch.getSelected()); // toggle if (ch.getSelected()) { v.setBackgroundResource(R.drawable.row_blue_selected); } else { v.setBackgroundResource(R.drawable.row_blue); } // TESTING Log.d("onClick() Channel", "onClick() Channel: " + ch.getTitle() + " selected: " + ch.getSelected()); } }); return mvh; } Code of getView(...): @Override public View getView(int position, View view, ViewGroup parent) { ViewHolder holder; // When view is not null, we can reuse it directly, there is no need // to reinflate it. // We only inflate a new View when the view supplied by ListView is // null. if (view == null) { view = mInflater.inflate(mViewId, null); // call own implementation holder = createHolder(view); // TEST // we set the holder as tag view.setTag(holder); } else { // get holder back...much faster than inflate holder = (ViewHolder) view.getTag(); } // we must update the object's reference holder.data = getItem(position); // call the own implementation bindHolder(holder); return view; } I really would appreciate any idea how to solve this! :) If more information is needed please tell me. Thanks in advance!

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• WCF Endpoints & Binding Configuration Issues

  - by CodeAbundance

  I am running into a very strange issue here folks. For simplicity I created a project for the sole purpose of testing the issue outside the framework of a larger application and still encountered what is either a bug in WCF within Visual Studio 2010 or something related to my WCF newbie skill set : ) Here is the issue: I have a WCF endpoint I created running inside of an MVC3 project called "SimpleMethod". The method runs inside of a .svc file on the root of the application and it returns a bool. Using the "WCF Service Configuration Editor" I have added the endpoint to my Web.Config along with a called "LargeImageBinding". Here is the service: [OperationContract] public bool SimpleMethod() { return true; } And the Web.Config generated by the Config Tool: <system.serviceModel> <bindings> <wsHttpBinding> <binding name="LargeImageBinding" closeTimeout="00:10:00" /> </wsHttpBinding> </bindings> <services> <service name="WCFEndpoints.ServiceTestOne"> <endpoint address="/ServiceTestOne.svc" binding="wsHttpBinding" bindingConfiguration="LargeImageBinding" contract="WCFEndpoints.IServiceTestOne" /> </service> </services> <behaviors> <serviceBehaviors> <behavior name=""> <serviceMetadata httpGetEnabled="true" /> <serviceDebug includeExceptionDetailInFaults="false" /> </behavior> </serviceBehaviors> </behaviors> <serviceHostingEnvironment multipleSiteBindingsEnabled="true" /> The service renders fine and you can see the endpoint when you navigate to: http://localhost:57364/ServiceTestOne.svc - Now the issue occurs when I create a separate project to consume the service. I add a service reference to a running instance of the above project, point it to: http://localhost:57364/ServiceTestOne.svc Here is the weird part. The service automatically generates just fine but In the Web.Config the endpoint that is generated looks like this: <client> <endpoint address="http://localhost:57364/ServiceTestOne.svc/ServiceTestOne.svc" binding="wsHttpBinding" bindingConfiguration="WSHttpBinding_IServiceTestOne" contract="ServiceTestOne.IServiceTestOne" name="WSHttpBinding_IServiceTestOne"> As you can see it lists the "ServiceTestOne.svc" portion of the address twice! When I make a call to the the service I get the following error: The remote server returned an error: (404) Not Found. I tried removing the extra "/ServiceTestOne.svc" at the end of the endpoint address in the above config, and I get the same exact error. Now what DOES work is if I go back to the WCF application and remove the custom endpoint and binding references in the Web.Config (everything in the "services" and "bindings" tags) then go back to the consumer application, update the reference to the service and make the call to SimpleMethod()....BOOM works like a charm and I get back a bool set to true. The thing is, I need to make custom binding configurations in order to allow for access to the service outside of the defaults, and from what I can tell, any attempt to create custom bindings makes the endpoints seem to run fine, but fail when an actual method call is made. Can anyone see any flaw in how I am putting this together? Thank you for your time - I have been running in circles with this for about a week!

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• Array not showing in Jlist but filled in console

  - by OVERTONE

  Hey there. been a busy debugger today. ill give ths short version. ive made an array list that takes names from a database. then i put the contents of the arraylist into an array of strings. now i want too display the arrays contents in a JList. the weird thing is it was working earlier. and ive two methods. ones just a little practice too make sure i was adding to the Jlist correctly. so heres the key codes. this is the layout of my code. variables constructor methods in my variables i have these 3 defined String[] contactListNames = new String[5]; ArrayList<String> rowNames = new ArrayList<String>(); JList contactList = new JList(contactListNames); simple enough. in my constructor i have them again. contactListNames = new String[5]; contactList = new JList(contactListNames); //i dont have the array list defined though. printSqlDetails(); // the prinSqldetails was too make sure that the connectionw as alright. and its working fine. fillContactList(); // this is the one thats causing me grief. its where all the work happens. // fillContactListTest(); // this was the tester that makes sure its adding to the list alright. heres the code for fillContactListTest() public void fillContactListTest() { for(int i = 0;i<3;i++) { try { String contact; System.out.println(" please fill the list at index "+ i); Scanner in = new Scanner(System.in); contact = in.next(); contactListNames[i] = contact; in.nextLine(); } catch(Exception e) { e.printStackTrace(); } } } heres the main one thats supposed too work. public void fillContactList() { int i =0; createConnection(); ArrayList<String> rowNames = new ArrayList<String>(); try { Statement stmt = conn.createStatement(); ResultSet namesList = stmt.executeQuery("SELECT name FROM Users"); try { while (namesList.next()) { rowNames.add(namesList.getString(1)); contactListNames =(String[])rowNames.toArray(new String[rowNames.size()]); // this used to print out contents of array list // System.out.println("" + rowNames); while(i<contactListNames.length) { System.out.println(" " + contactListNames[i]); i++; } } } catch(SQLException q) { q.printStackTrace(); } conn.commit(); stmt.close(); conn.close(); } catch(SQLException e) { e.printStackTrace(); } } i really need help here. im at my wits end. i just cant see why the first method would add to the JList no problem. but the second one wont. both the contactListNames array and array list can print fine and have the names in them. but i must be transfering them too the jlist wrong. please help p.s im aware this is long. but trust me its the short version.

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• Anything wrong with this function for comparing floats?

  - by Michael Borgwardt

  When my Floating-Point Guide was yesterday published on slashdot, I got a lot of flak for my suggested comparison function, which was indeed inadequate. So I finally did the sensible thing and wrote a test suite to see whether I could get them all to pass. Here is my result so far. And I wonder if this is really as good as one can get with a generic (i.e. not application specific) float comparison function, or whether I still missed some edge cases. import static org.junit.Assert.assertFalse; import static org.junit.Assert.assertTrue; import org.junit.Test; public class NearlyEqualsTest { public static boolean nearlyEqual(float a, float b) { final float epsilon = 0.000001f; final float absA = Math.abs(a); final float absB = Math.abs(b); final float diff = Math.abs(a-b); if (a*b==0) { // a or b or both are zero // relative error is not meaningful here return diff < Float.MIN_VALUE / epsilon; } else { // use relative error return diff / (absA+absB) < epsilon; } } /** Regular large numbers - generally not problematic */ @Test public void big() { assertTrue(nearlyEqual(1000000f, 1000001f)); assertTrue(nearlyEqual(1000001f, 1000000f)); assertFalse(nearlyEqual(10000f, 10001f)); assertFalse(nearlyEqual(10001f, 10000f)); } /** Negative large numbers */ @Test public void bigNeg() { assertTrue(nearlyEqual(-1000000f, -1000001f)); assertTrue(nearlyEqual(-1000001f, -1000000f)); assertFalse(nearlyEqual(-10000f, -10001f)); assertFalse(nearlyEqual(-10001f, -10000f)); } /** Numbers around 1 */ @Test public void mid() { assertTrue(nearlyEqual(1.0000001f, 1.0000002f)); assertTrue(nearlyEqual(1.0000002f, 1.0000001f)); assertFalse(nearlyEqual(1.0002f, 1.0001f)); assertFalse(nearlyEqual(1.0001f, 1.0002f)); } /** Numbers around -1 */ @Test public void midNeg() { assertTrue(nearlyEqual(-1.000001f, -1.000002f)); assertTrue(nearlyEqual(-1.000002f, -1.000001f)); assertFalse(nearlyEqual(-1.0001f, -1.0002f)); assertFalse(nearlyEqual(-1.0002f, -1.0001f)); } /** Numbers between 1 and 0 */ @Test public void small() { assertTrue(nearlyEqual(0.000000001000001f, 0.000000001000002f)); assertTrue(nearlyEqual(0.000000001000002f, 0.000000001000001f)); assertFalse(nearlyEqual(0.000000000001002f, 0.000000000001001f)); assertFalse(nearlyEqual(0.000000000001001f, 0.000000000001002f)); } /** Numbers between -1 and 0 */ @Test public void smallNeg() { assertTrue(nearlyEqual(-0.000000001000001f, -0.000000001000002f)); assertTrue(nearlyEqual(-0.000000001000002f, -0.000000001000001f)); assertFalse(nearlyEqual(-0.000000000001002f, -0.000000000001001f)); assertFalse(nearlyEqual(-0.000000000001001f, -0.000000000001002f)); } /** Comparisons involving zero */ @Test public void zero() { assertTrue(nearlyEqual(0.0f, 0.0f)); assertFalse(nearlyEqual(0.00000001f, 0.0f)); assertFalse(nearlyEqual(0.0f, 0.00000001f)); } /** Comparisons of numbers on opposite sides of 0 */ @Test public void opposite() { assertFalse(nearlyEqual(1.000000001f, -1.0f)); assertFalse(nearlyEqual(-1.0f, 1.000000001f)); assertFalse(nearlyEqual(-1.000000001f, 1.0f)); assertFalse(nearlyEqual(1.0f, -1.000000001f)); assertTrue(nearlyEqual(10000f*Float.MIN_VALUE, -10000f*Float.MIN_VALUE)); } /** * The really tricky part - comparisons of numbers * very close to zero. */ @Test public void ulp() { assertTrue(nearlyEqual(Float.MIN_VALUE, -Float.MIN_VALUE)); assertTrue(nearlyEqual(-Float.MIN_VALUE, Float.MIN_VALUE)); assertTrue(nearlyEqual(Float.MIN_VALUE, 0)); assertTrue(nearlyEqual(0, Float.MIN_VALUE)); assertTrue(nearlyEqual(-Float.MIN_VALUE, 0)); assertTrue(nearlyEqual(0, -Float.MIN_VALUE)); assertFalse(nearlyEqual(0.000000001f, -Float.MIN_VALUE)); assertFalse(nearlyEqual(0.000000001f, Float.MIN_VALUE)); assertFalse(nearlyEqual(Float.MIN_VALUE, 0.000000001f)); assertFalse(nearlyEqual(-Float.MIN_VALUE, 0.000000001f)); assertFalse(nearlyEqual(1e20f*Float.MIN_VALUE, 0.0f)); assertFalse(nearlyEqual(0.0f, 1e20f*Float.MIN_VALUE)); assertFalse(nearlyEqual(1e20f*Float.MIN_VALUE, -1e20f*Float.MIN_VALUE)); } }

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• Suggestions on how to map from Domain (ORM) objects to Data Transfer Objects (DTO)

  - by FryHard

  The current system that I am working on makes use of Castle Activerecord to provide ORM (Object Relational Mapping) between the Domain objects and the database. This is all well and good and at most times actually works well! The problem comes about with Castle Activerecords support for asynchronous execution, well, more specifically the SessionScope that manages the session that objects belong to. Long story short, bad stuff happens! We are therefore looking for a way to easily convert (think automagically) from the Domain objects (who know that a DB exists and care) to the DTO object (who know nothing about the DB and care not for sessions, mapping attributes or all thing ORM). Does anyone have suggestions on doing this. For the start I am looking for a basic One to One mapping of object. Domain object Person will be mapped to say PersonDTO. I do not want to do this manually since it is a waste. Obviously reflection comes to mind, but I am hoping with some of the better IT knowledge floating around this site that "cooler" will be suggested. Oh, I am working in C#, the ORM objects as said before a mapped with Castle ActiveRecord. Example code: By @ajmastrean's request I have linked to an example that I have (badly) mocked together. The example has a capture form, capture form controller, domain objects, activerecord repository and an async helper. It is slightly big (3MB) because I included the ActiveRecored dll's needed to get it running. You will need to create a database called ActiveRecordAsync on your local machine or just change the .config file. Basic details of example: The Capture Form The capture form has a reference to the contoller private CompanyCaptureController MyController { get; set; } On initialise of the form it calls MyController.Load() private void InitForm () { MyController = new CompanyCaptureController(this); MyController.Load(); } This will return back to a method called LoadComplete() public void LoadCompleted (Company loadCompany) { _context.Post(delegate { CurrentItem = loadCompany; bindingSource.DataSource = CurrentItem; bindingSource.ResetCurrentItem(); //TOTO: This line will thow the exception since the session scope used to fetch loadCompany is now gone. grdEmployees.DataSource = loadCompany.Employees; }, null); } } this is where the "bad stuff" occurs, since we are using the child list of Company that is set as Lazy load. The Controller The controller has a Load method that was called from the form, it then calls the Asyc helper to asynchronously call the LoadCompany method and then return to the Capture form's LoadComplete method. public void Load () { new AsyncListLoad<Company>().BeginLoad(LoadCompany, Form.LoadCompleted); } The LoadCompany() method simply makes use of the Repository to find a know company. public Company LoadCompany() { return ActiveRecordRepository<Company>.Find(Setup.company.Identifier); } The rest of the example is rather generic, it has two domain classes which inherit from a base class, a setup file to instert some data and the repository to provide the ActiveRecordMediator abilities.

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• Android: MediaPlayer gapless or seamless Video Playing

  - by John Wang

  I can play the videos fine back to back by implementing the OnCompletionListener to set the data source to a different file. No problems there. I call reset() and prepare() just fine. What I haven't been able to figure out, is how to get rid of the 1-2 second gap screen flicker between the data source change and the new video starting. The gap shows a black screen, and I haven't found any way to get around it. I've tried setting the background of the parent view to an image, but it manages to bypass that. Even if the SurfaceView is transparent (which it is by default.) I've also tried to have the multiple video files played at the same time, and switching mediaplayer's display when one ends and the other is supposed to start. The last thing I tried, was to have a second view in the background that I show temporarily while the video is "preparing" and removing it when the video is ready to start. That also wasn't very seamless. Is there any way to get rid of that gap. Running a video in a loop works wonderfully and does exactly what I want with the exception that it's looking through the same video instead of playing a different one that I pick. main.xml <?xml version="1.0" encoding="utf-8"?> <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:background="@drawable/background" android:layout_height="fill_parent"> <SurfaceView android:id="@+id/surface" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_gravity="center"> </SurfaceView> </FrameLayout> Player.java public class Player extends Activity implements OnCompletionListener, MediaPlayer.OnPreparedListener, SurfaceHolder.Callback { private MediaPlayer player; private SurfaceView surface; private SurfaceHolder holder; public void onCreate(Bundle b) { super.onCreate(b); setContentView(R.layout.main); surface = (SurfaceView)findViewById(R.id.surface); holder = surface.getHolder(); holder.addCallback(this); holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); } public void onCompletion(MediaPlayer arg0) { File clip = new File(Environment.getExternalStorageDirectory(),"file2.mp4"); playVideo(clip.getAbsolutePath()); } public void onPrepared(MediaPlayer mediaplayer) { holder.setFixedSize(player.getVideoWidth(), player.getVideoHeight()); player.start(); } private void playVideo(String url) { try { File clip = new File(Environment.getExternalStorageDirectory(),"file1.mp4"); if (player == null) { player = new MediaPlayer(); player.setScreenOnWhilePlaying(true); } else { player.stop(); player.reset(); } player.setDataSource(url); player.setDisplay(holder); player.setOnPreparedListener(this); player.prepare(); player.setOnCompletionListener(this); } catch (Throwable t) { Log.e("ERROR", "Exception Error", t); } }

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