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  • understand SimpleTimeZone and DST Test

    - by Cygnusx1
    I Have an issue with the use of SimpleTimeZone class in Java. First, the JavaDoc is nice but not quite easy to understand in regards of the start and end Rules. But with the help of some example found on the web, i managed to get it right (i still don't understand why 8 represents the second week of a month in day_of_month!!! but whatever) Now i have written a simple Junit test to validate what i understand: package test; import static org.junit.Assert.assertEquals; import java.sql.Timestamp; import java.util.Calendar; import java.util.GregorianCalendar; import java.util.SimpleTimeZone; import org.apache.log4j.Logger; import org.junit.Test; public class SimpleTimeZoneTest { Logger log = Logger.getLogger(SimpleTimeZoneTest.class); @Test public void testTimeZoneWithDST() throws Exception { Calendar testDateEndOut = new GregorianCalendar(2012, Calendar.NOVEMBER, 4, 01, 59, 59); Calendar testDateEndIn = new GregorianCalendar(2012, Calendar.NOVEMBER, 4, 02, 00, 00); Calendar testDateStartOut = new GregorianCalendar(2012, Calendar.MARCH, 11, 01, 59, 59); Calendar testDateStartIn = new GregorianCalendar(2012, Calendar.MARCH, 11, 02, 00, 00); SimpleTimeZone est = new SimpleTimeZone(-5 * 60 * 60 * 1000, "EST"); est.setStartRule(Calendar.MARCH, 8, -Calendar.SUNDAY, 2 * 60 * 60 * 1000); est.setEndRule(Calendar.NOVEMBER, 1, Calendar.SUNDAY, 2 * 60 * 60 * 1000); Calendar theCal = new GregorianCalendar(est); theCal.setTimeInMillis(testDateEndOut.getTimeInMillis()); log.info(" Cal date = " + new Timestamp(theCal.getTimeInMillis()) + " : " + theCal.getTimeZone().getDisplayName()); log.info(" Cal use DST = " + theCal.getTimeZone().useDaylightTime()); log.info(" Cal In DST = " + theCal.getTimeZone().inDaylightTime(theCal.getTime())); log.info("offset = " + theCal.getTimeZone().getOffset(theCal.getTimeInMillis())); log.info("DTS offset= " + theCal.getTimeZone().getDSTSavings()); assertEquals("End date Should be In DST", true, theCal.getTimeZone().inDaylightTime(theCal.getTime())); theCal.setTimeInMillis(testDateEndIn.getTimeInMillis()); log.info(" Cal date = " + new Timestamp(theCal.getTimeInMillis()) + " : " + theCal.getTimeZone().getDisplayName()); log.info(" Cal use DST = " + theCal.getTimeZone().useDaylightTime()); log.info(" Cal In DST = " + theCal.getTimeZone().inDaylightTime(theCal.getTime())); log.info("offset = " + theCal.getTimeZone().getOffset(theCal.getTimeInMillis())); log.info("DTS offset= " + theCal.getTimeZone().getDSTSavings()); assertEquals("End date Should be Out DST", false, theCal.getTimeZone().inDaylightTime(theCal.getTime())); theCal.setTimeInMillis(testDateStartIn.getTimeInMillis()); log.info(" Cal date = " + new Timestamp(theCal.getTimeInMillis()) + " : " + theCal.getTimeZone().getDisplayName()); log.info(" Cal use DST = " + theCal.getTimeZone().useDaylightTime()); log.info(" Cal In DST = " + theCal.getTimeZone().inDaylightTime(theCal.getTime())); log.info("offset = " + theCal.getTimeZone().getOffset(theCal.getTimeInMillis())); log.info("DTS offset= " + theCal.getTimeZone().getDSTSavings()); assertEquals("Start date Should be in DST", true, theCal.getTimeZone().inDaylightTime(theCal.getTime())); theCal.setTimeInMillis(testDateStartOut.getTimeInMillis()); log.info(" Cal date = " + new Timestamp(theCal.getTimeInMillis()) + " : " + theCal.getTimeZone().getDisplayName()); log.info(" Cal use DST = " + theCal.getTimeZone().useDaylightTime()); log.info(" Cal In DST = " + theCal.getTimeZone().inDaylightTime(theCal.getTime())); log.info("offset = " + theCal.getTimeZone().getOffset(theCal.getTimeInMillis())); log.info("DTS offset= " + theCal.getTimeZone().getDSTSavings()); assertEquals("Start date Should be Out DST", false, theCal.getTimeZone().inDaylightTime(theCal.getTime())); } } Ok, i want to test the date limits to see if the inDaylightTime return the right thing! So, my rules are : DST start the second sunday of March at 2am DST end the first sunday of november at 2am In 2012 (now) this give us the march 11 at 2am and November 4 at 2am You can see my test dates are set properly!!! Well here is the output of my test run: 2012-11-01 18:22:44,344 INFO [test.SimpleTimeZoneTest] - < Cal date = 2012-11-04 01:59:59.0 : Eastern Standard Time> 2012-11-01 18:22:44,345 INFO [test.SimpleTimeZoneTest] - < Cal use DST = true> 2012-11-01 18:22:44,345 INFO [test.SimpleTimeZoneTest] - < Cal In DST = false> 2012-11-01 18:22:44,345 INFO [test.SimpleTimeZoneTest] - <offset = -18000000> 2012-11-01 18:22:44,345 INFO [test.SimpleTimeZoneTest] - <DTS offset= 3600000> My first assert just fails and tell me that 2012-11-04 01:59:59 is not inDST... !!!!??? If i put 2012-11-04 00:59:59, the test pass! This 1 hour gap just puzzle me... can anyone explain this behavior? Oh, btw, if anyone could elaborate on the : est.setStartRule(Calendar.MARCH, 8, -Calendar.SUNDAY, 2 * 60 * 60 * 1000); Why 8 means second week of march... and the -SUNDAY. I can't figure out this thing on a real calendar example!!! Thanks

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  • Implementation question involving implementing an interface

    - by Vivin Paliath
    I'm writing a set of collection classes for different types of Trees. I'm doing this as a learning exercise and I'm also hoping it turns out to be something useful. I really want to do this the right way and so I've been reading Effective Java and I've also been looking at the way Joshua Bloch implemented the collection classes by looking at the source. I seem to have a fair idea of what is being done, but I still have a few things to sort out. I have a Node<T> interface and an AbstractNode<T> class that implements the Node interface. I then created a GenericNode<T> (a node that can have 0 to n children, and that is part of an n-ary tree) class that extends AbstractNode<T> and implements Node<T>. This part was easy. Next, I created a Tree<T> interface and an AbstractTree<T> class that implements the Tree<T> interface. After that, I started writing a GenericTree<T> class that extends AbstractTree<T> and implements Tree<T>. This is where I started having problems. As far as the design is concerned, a GenericTree<T> can only consist of nodes of type GenericTreeNode<T>. This includes the root. In my Tree<T> interface I have: public interface Tree<T> { void setRoot(Node<T> root); Node<T> getRoot(); List<Node<T>> postOrder(); ... rest omitted ... } And, AbstractTree<T> implements this interface: public abstract class AbstractTree<T> implements Tree<T> { protected Node<T> root; protected AbstractTree() { } protected AbstractTree(Node<T> root) { this.root = root; } public void setRoot(Node<T> root) { this.root = root; } public Node<T> getRoot() { return this.root; } ... rest omitted ... } In GenericTree<T>, I can have: public GenericTree(Node<T> root) { super(root); } But what this means is that you can create a generic tree using any subtype of Node<T>. You can also set the root of a tree to any subtype of Node<T>. I want to be able to restrict the type of the node to the type of the tree that it can represent. To fix this, I can do this: public GenericTree(GenericNode<T> root) { super(root); } However, setRoot still accepts a parameter of type Node<T>. Which means a user can still create a tree with the wrong type of root node. How do I enforce this constraint? The only way I can think of doing is either: Do an instanceof which limits the check to runtime. I'm not a huge fan of this. Remove setRoot from the interface and have the base class implement this method. This means that it is not part of the contract and anyone who wants to make a new type of tree needs to remember to implement this method. Is there a better way? The second question I have concerns the return type of postOrder which is List<Node<T>>. This means that if a user is operating on a GenericTree<T> object and calls postOrder, he or she receives a list that consists of Node<T> objects. This means when iterating through (using a foreach construct) they would have perform an explicit cast to GenericNode<T> if they want to use methods that are only defined in that class. I don't like having to place this burden on the user. What are my options in this case? I can only think of removing the method from the interface and have the subclass implement this method making sure that it returns a list of appropriate subtype of Node<T>. However, this once again removes it from the contract and it's anyone who wants to create a new type of tree has to remember to implement this method. Is there a better way?

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  • Help needed with Javascript Variable Scope / OOP and Call Back Functions

    - by gargantaun
    I think this issue goes beyond typical variable scope and closure stuff, or maybe I'm an idiot. Here goes anyway... I'm creating a bunch of objects on the fly in a jQuery plugin. The object look something like this function WedgePath(canvas){ this.targetCanvas = canvas; this.label; this.logLabel = function(){ console.log(this.label) } } the jQuery plugin looks something like this (function($) { $.fn.myPlugin = function() { return $(this).each(function() { // Create Wedge Objects for(var i = 1; i <= 30; i++){ var newWedge = new WedgePath(canvas); newWedge.label = "my_wedge_"+i; globalFunction(i, newWedge]); } }); } })(jQuery); So... the plugin creates a bunch of wedgeObjects, then calls 'globalFunction' for each one, passing in the latest WedgePath instance. Global function looks like this. function globalFunction(indicator_id, pWedge){ var targetWedge = pWedge; targetWedge.logLabel(); } What happens next is that the console logs each wedges label correctly. However, I need a bit more complexity inside globalFunction. So it actually looks like this... function globalFunction(indicator_id, pWedge){ var targetWedge = pWedge; someSql = "SELECT * FROM myTable WHERE id = ?"; dbInterface.executeSql(someSql, [indicator_id], function(transaction, result){ targetWedge.logLabel(); }) } There's a lot going on here so i'll explain. I'm using client side database storage (WebSQL i call it). 'dbInterface' an instance of a simple javascript object I created which handles the basics of interacting with a client side database [shown at the end of this question]. the executeSql method takes up to 4 arguments The SQL String an optional arguments array an optional onSuccess handler an optional onError handler (not used in this example) What I need to happen is: When the WebSQL query has completed, it takes some of that data and manipulates some attribute of a particular wedge. But, when I call 'logLabel' on an instance of WedgePath inside the onSuccess handler, I get the label of the very last instance of WedgePath that was created way back in the plugin code. Now I suspect that the problem lies in the var newWedge = new WedgePath(canvas); line. So I tried pushing each newWedge into an array, which I thought would prevent that line from replacing or overwriting the WedgePath instance at every iteration... wedgeArray = []; // Inside the plugin... for(var i = 1; i <= 30; i++){ var newWedge = new WedgePath(canvas); newWedge.label = "my_wedge_"+i; wedgeArray.push(newWedge); } for(var i = 0; i < wedgeArray.length; i++){ wedgeArray[i].logLabel() } But again, I get the last instance of WedgePath to be created. This is driving me nuts. I apologise for the length of the question but I wanted to be as clear as possible. END ============================================================== Also, here's the code for dbInterface object should it be relevant. function DatabaseInterface(db){ var DB = db; this.sql = function(sql, arr, pSuccessHandler, pErrorHandler){ successHandler = (pSuccessHandler) ? pSuccessHandler : this.defaultSuccessHandler; errorHandler = (pErrorHandler) ? pErrorHandler : this.defaultErrorHandler; DB.transaction(function(tx){ if(!arr || arr.length == 0){ tx.executeSql(sql, [], successHandler, errorHandler); }else{ tx.executeSql(sql,arr, successHandler, errorHandler) } }); } // ---------------------------------------------------------------- // A Default Error Handler // ---------------------------------------------------------------- this.defaultErrorHandler = function(transaction, error){ // error.message is a human-readable string. // error.code is a numeric error code console.log('WebSQL Error: '+error.message+' (Code '+error.code+')'); // Handle errors here var we_think_this_error_is_fatal = true; if (we_think_this_error_is_fatal) return true; return false; } // ---------------------------------------------------------------- // A Default Success Handler // This doesn't do anything except log a success message // ---------------------------------------------------------------- this.defaultSuccessHandler = function(transaction, results) { console.log("WebSQL Success. Default success handler. No action taken."); } }

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  • WCF 4: Fileless Activation Fails On XP (IIS 5) that has SSL port enabled.

    - by Richard Collette
    I have a service being hosted in IIS on XP via fileless activation. The service starts fine when there is no SSL port enabled for IIS but when the SSL port is enabled, I get the error message: System.ServiceModel.ServiceActivationException: The service '/SkillsPrototype.Web/services/Linkage.svc' cannot be activated due to an exception during compilation. The exception message is: A binding instance has already been associated to listen URI 'http://rcollet.hsb-corp.hsb.com/SkillsPrototype.Web/Services/Linkage.svc'. If two endpoints want to share the same ListenUri, they must also share the same binding object instance. The two conflicting endpoints were either specified in AddServiceEndpoint() calls, in a config file, or a combination of AddServiceEndpoint() and config. . ---> System.InvalidOperationException: A binding instance has already been associated to listen URI 'http://rcollet.hsb-corp.hsb.com/SkillsPrototype.Web/Services/Linkage.svc'. If two endpoints want to share the same ListenUri, they must also share the same binding object instance. The two conflicting endpoints were either specified in AddServiceEndpoint() calls, in a config file, or a combination of AddServiceEndpoint() and config. My service model configuration is <system.serviceModel> <diagnostics wmiProviderEnabled="true"> <messageLogging logEntireMessage="true" logMalformedMessages="true" logMessagesAtServiceLevel="true" logMessagesAtTransportLevel="true" maxMessagesToLog="3000"/> </diagnostics> <standardEndpoints> <webHttpEndpoint> <standardEndpoint name="" helpEnabled="true" automaticFormatSelectionEnabled="true" /> </webHttpEndpoint> </standardEndpoints> <behaviors> <serviceBehaviors> <behavior> <serviceMetadata httpGetEnabled="true"/> <serviceDebug includeExceptionDetailInFaults="true" /> </behavior> </serviceBehaviors> </behaviors> <bindings> <webHttpBinding> <binding> <security mode="None"> <transport clientCredentialType="None"/> </security> </binding> </webHttpBinding> </bindings> <protocolMapping> </protocolMapping> <services> </services> <serviceHostingEnvironment multipleSiteBindingsEnabled="false"> <serviceActivations> <clear/> <add factory="System.ServiceModel.Activation.WebScriptServiceHostFactory" service="SkillsPrototype.ServiceModel.Linkage" relativeAddress="~/Services/Linkage.svc"/> </serviceActivations> </serviceHostingEnvironment> </system.serviceModel> When you look in the svclog file, there two base addresses that are returned when SSL is enabled, one for http and one for https. I suspect that this is part of the issue but I am not sure how to resolve it. <E2ETraceEvent xmlns="http://schemas.microsoft.com/2004/06/E2ETraceEvent"> <System xmlns="http://schemas.microsoft.com/2004/06/windows/eventlog/system"> <EventID>524333</EventID> <Type>3</Type> <SubType Name="Information">0</SubType> <Level>8</Level> <TimeCreated SystemTime="2010-06-16T17:40:55.8168605Z" /> <Source Name="System.ServiceModel" /> <Correlation ActivityID="{95927f9a-fa90-46f4-af8b-721322a87aaa}" /> <Execution ProcessName="aspnet_wp" ProcessID="1888" ThreadID="5" /> <Channel/> <Computer>RCOLLET</Computer> </System> <ApplicationData> <TraceData> <DataItem> <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Information"> <TraceIdentifier>http://msdn.microsoft.com/en-US/library/System.ServiceModel.ServiceHostBaseAddresses.aspx</TraceIdentifier> <Description>ServiceHost base addresses.</Description> <AppDomain>/LM/w3svc/1/ROOT/SkillsPrototype.Web-1-129211836532542949</AppDomain> <Source>System.ServiceModel.WebScriptServiceHost/49153359</Source> <ExtendedData xmlns="http://schemas.microsoft.com/2006/08/ServiceModel/CollectionTraceRecord"> <BaseAddresses> <Address>http://rcollet.hsb-corp.hsb.com/SkillsPrototype.Web/Services/Linkage.svc</Address> <Address>https://rcollet.hsb-corp.hsb.com/SkillsPrototype.Web/Services/Linkage.svc</Address> </BaseAddresses> </ExtendedData> </TraceRecord> </DataItem> </TraceData> </ApplicationData> </E2ETraceEvent> I can't post the full service log due to character limits on the post.

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  • JSF : How to refresh required field in ajax request

    - by Tama
    Ok, here you are the core problem. The page. I have two required "input text". A command button that changes the bean value and reRenderes the "job" object. <a4j:form id="pervForm"> SURNAME:<h:inputText id="surname" label="Surname" value="#{prevManager.surname}" required="true" /> <br/> JOB:<h:inputText value="#{prevManager.job}" id="job" maxlength="10" size="10" label="#{msg.common_label_job}" required="true" /> <br/> <a4j:commandButton value="Set job to Programmer" ajaxSingle="true" reRender="job"> <a4j:actionparam name="jVal" value="Programmer" assignTo="#{prevManager.job}"/> </a4j:commandButton> <h:commandButton id="save" value="save" action="save" class="HATSBUTTON"/> </a4j:form> Here the simple manager: public class PrevManager { private String surname; private String job; public String getSurname() { return surname; } public void setSurname(String surname) { this.surname = surname; } public String getJob() { return job; } public void setJob(String job) { this.job = job; } public String save() { //do something } } Let's do this: Write something on the Job input text (such as "teacher"). Leave empty the surname. Save. Validation error appears (surname is mandatory). Press "Set job to Programmer": nothing happens. Checking the bean value, I discovered that it is correctly updated, indeed the component on the page is not updated! Well, according to the JBoss Docs I found: Ajax region is a key ajax component. It limits the part of the component tree to be processed on the server side when ajax request comes. Processing means invocation during Decode, Validation and Model Update phase. Most common reasons to use a region are: -avoiding the aborting of the JSF lifecycle processing during the validation of other form input unnecessary for given ajax request; -defining the different strategies when events will be delivered (immediate="true/false") -showing an individual indicator of an ajax status -increasing the performance of the rendering processing (selfRendered="true/false", renderRegionOnly="true/false") The following two examples show the situation when a validation error does not allow to process an ajax input. Type the name. The outputText component should reappear after you. However, in the first case, this activity will be aborted because of the other field with required="true". You will see only the error message while the "Job" field is empty. Here you are the example: <ui:composition xmlns="http://www.w3.org/1999/xhtml" xmlns:ui="http://java.sun.com/jsf/facelets" xmlns:h="http://java.sun.com/jsf/html" xmlns:f="http://java.sun.com/jsf/core" xmlns:a4j="http://richfaces.org/a4j" xmlns:rich="http://richfaces.org/rich"> <style> .outergridvalidationcolumn { padding: 0px 30px 10px 0px; } </style> <a4j:outputPanel ajaxRendered="true"> <h:messages style="color:red" /> </a4j:outputPanel> <h:panelGrid columns="2" columnClasses="outergridvalidationcolumn"> <h:form id="form1"> <h:panelGrid columns="2"> <h:outputText value="Name" /> <h:inputText value="#{userBean.name}"> <a4j:support event="onkeyup" reRender="outname" /> </h:inputText> <h:outputText value="Job" /> <h:inputText required="true" id="job2" value="#{userBean.job}" /> </h:panelGrid> </h:form> <h:form id="form2"> <h:panelGrid columns="2"> <h:outputText value="Name" /> <a4j:region> <h:inputText value="#{userBean.name}"> <a4j:support event="onkeyup" reRender="outname" /> </h:inputText> </a4j:region> <h:outputText value="Job" /> <h:inputText required="true" id="job1" value="#{userBean.job}" /> </h:panelGrid> </h:form> </h:panelGrid> <h:outputText id="outname" style="font-weight:bold" value="Typed Name: #{userBean.name}" /> <br /> </ui:composition> Form1: the behaviour is incorrect. I need to fill the job and then the name. Form2: the behaviour is correct. I do not need to fill the job to see the correct value. Unfortunately using Ajax region does not help (indeed I used it in a bad way ...) because my fields are both REQUIRED. That's the main different. Any idea? Many thanks.

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  • Trying to reduce the speed overhead of an almost-but-not-quite-int number class

    - by Fumiyo Eda
    I have implemented a C++ class which behaves very similarly to the standard int type. The difference is that it has an additional concept of "epsilon" which represents some tiny value that is much less than 1, but greater than 0. One way to think of it is as a very wide fixed point number with 32 MSBs (the integer parts), 32 LSBs (the epsilon parts) and a huge sea of zeros in between. The following class works, but introduces a ~2x speed penalty in the overall program. (The program includes code that has nothing to do with this class, so the actual speed penalty of this class is probably much greater than 2x.) I can't paste the code that is using this class, but I can say the following: +, -, +=, <, > and >= are the only heavily used operators. Use of setEpsilon() and getInt() is extremely rare. * is also rare, and does not even need to consider the epsilon values at all. Here is the class: #include <limits> struct int32Uepsilon { typedef int32Uepsilon Self; int32Uepsilon () { _value = 0; _eps = 0; } int32Uepsilon (const int &i) { _value = i; _eps = 0; } void setEpsilon() { _eps = 1; } Self operator+(const Self &rhs) const { Self result = *this; result._value += rhs._value; result._eps += rhs._eps; return result; } Self operator-(const Self &rhs) const { Self result = *this; result._value -= rhs._value; result._eps -= rhs._eps; return result; } Self operator-( ) const { Self result = *this; result._value = -result._value; result._eps = -result._eps; return result; } Self operator*(const Self &rhs) const { return this->getInt() * rhs.getInt(); } // XXX: discards epsilon bool operator<(const Self &rhs) const { return (_value < rhs._value) || (_value == rhs._value && _eps < rhs._eps); } bool operator>(const Self &rhs) const { return (_value > rhs._value) || (_value == rhs._value && _eps > rhs._eps); } bool operator>=(const Self &rhs) const { return (_value >= rhs._value) || (_value == rhs._value && _eps >= rhs._eps); } Self &operator+=(const Self &rhs) { this->_value += rhs._value; this->_eps += rhs._eps; return *this; } Self &operator-=(const Self &rhs) { this->_value -= rhs._value; this->_eps -= rhs._eps; return *this; } int getInt() const { return(_value); } private: int _value; int _eps; }; namespace std { template<> struct numeric_limits<int32Uepsilon> { static const bool is_signed = true; static int max() { return 2147483647; } } }; The code above works, but it is quite slow. Does anyone have any ideas on how to improve performance? There are a few hints/details I can give that might be helpful: 32 bits are definitely insufficient to hold both _value and _eps. In practice, up to 24 ~ 28 bits of _value are used and up to 20 bits of _eps are used. I could not measure a significant performance difference between using int32_t and int64_t, so memory overhead itself is probably not the problem here. Saturating addition/subtraction on _eps would be cool, but isn't really necessary. Note that the signs of _value and _eps are not necessarily the same! This broke my first attempt at speeding this class up. Inline assembly is no problem, so long as it works with GCC on a Core i7 system running Linux!

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  • Loop crashing program having to do with 2D arrays

    - by user450062
    I am creating an encoding program and when I instruct the program to create a 5X5 grid based on the alphabet while skipping over letters that match up to certain pre-defined variables(which are given values by user input during runtime). I have a loop that instructs the loop to keep running until the values that access the array are out of bounds, the loop seems to cause the problem. This code is standardized so there shouldn't be much trouble compiling it in another compiler. Also would it be better to seperate my program into functions? here is the code: #include<iostream> #include<fstream> #include<cstdlib> #include<string> #include<limits> using namespace std; int main(){ while (!cin.fail()) { char type[81]; char filename[20]; char key [5]; char f[2] = "q"; char g[2] = "q"; char h[2] = "q"; char i[2] = "q"; char j[2] = "q"; char k[2] = "q"; char l[2] = "q"; int a = 1; int b = 1; int c = 1; int d = 1; int e = 1; string cipherarraytemplate[5][5]= { {"a","b","c","d","e"}, {"f","g","h","i","j"}, {"k","l","m","n","o"}, {"p","r","s","t","u"}, {"v","w","x","y","z"} }; string cipherarray[5][5]= { {"a","b","c","d","e"}, {"f","g","h","i","j"}, {"k","l","m","n","o"}, {"p","r","s","t","u"}, {"v","w","x","y","z"} }; cout<<"Enter the name of a file you want to create.\n"; cin>>filename; ofstream outFile; outFile.open(filename); outFile<<fixed; outFile.precision(2); outFile.setf(ios_base::showpoint); cin.ignore(std::numeric_limits<int>::max(),'\n'); cout<<"enter your codeword(codeword can have no repeating letters)\n"; cin>>key; while (key[a] != '\0' ){ while(b < 6){ cipherarray[b][c] = key[a]; if ( f == "q" ) { cipherarray[b][c] = f; } if ( f != "q" && g == "q" ) { cipherarray[b][c] = g; } if ( g != "q" && h == "q" ) { cipherarray[b][c] = h; } if ( h != "q" && i == "q" ) { cipherarray[b][c] = i; } if ( i != "q" && j == "q" ) { cipherarray[b][c] = j; } if ( j != "q" && k == "q" ) { cipherarray[b][c] = k; } if ( k != "q" && l == "q" ) { cipherarray[b][c] = l; } a++; b++; } c++; b = 1; } while (c < 6 || b < 6){ if (cipherarraytemplate[d][e] == f || cipherarraytemplate[d][e] == g || cipherarraytemplate[d][e] == h || cipherarraytemplate[d][e] == i || cipherarraytemplate[d][e] == j || cipherarraytemplate[d][e] == k || cipherarraytemplate[d][e] == l){ d++; } else { cipherarray[b][c] = cipherarraytemplate[d][e]; d++; b++; } if (d == 6){ d = 1; e++; } if (b == 6){ c++; b = 1; } } cout<<"now enter some text."<<endl<<"To end this program press Crtl-Z\n"; while(!cin.fail()){ cin.getline(type,81); outFile<<type<<endl; } outFile.close(); } } I know there is going to be some mid-forties guy out there who is going to stumble on to this post, he's have been programming for 20-some years and he's going to look at my code and say: "what is this guy doing".

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  • A Taxonomy of Numerical Methods v1

    - by JoshReuben
    Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

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  • C#/.NET Little Wonders: The Concurrent Collections (1 of 3)

    - by James Michael Hare
    Once again we consider some of the lesser known classes and keywords of C#.  In the next few weeks, we will discuss the concurrent collections and how they have changed the face of concurrent programming. This week’s post will begin with a general introduction and discuss the ConcurrentStack<T> and ConcurrentQueue<T>.  Then in the following post we’ll discuss the ConcurrentDictionary<T> and ConcurrentBag<T>.  Finally, we shall close on the third post with a discussion of the BlockingCollection<T>. For more of the "Little Wonders" posts, see the index here. A brief history of collections In the beginning was the .NET 1.0 Framework.  And out of this framework emerged the System.Collections namespace, and it was good.  It contained all the basic things a growing programming language needs like the ArrayList and Hashtable collections.  The main problem, of course, with these original collections is that they held items of type object which means you had to be disciplined enough to use them correctly or you could end up with runtime errors if you got an object of a type you weren't expecting. Then came .NET 2.0 and generics and our world changed forever!  With generics the C# language finally got an equivalent of the very powerful C++ templates.  As such, the System.Collections.Generic was born and we got type-safe versions of all are favorite collections.  The List<T> succeeded the ArrayList and the Dictionary<TKey,TValue> succeeded the Hashtable and so on.  The new versions of the library were not only safer because they checked types at compile-time, in many cases they were more performant as well.  So much so that it's Microsoft's recommendation that the System.Collections original collections only be used for backwards compatibility. So we as developers came to know and love the generic collections and took them into our hearts and embraced them.  The problem is, thread safety in both the original collections and the generic collections can be problematic, for very different reasons. Now, if you are only doing single-threaded development you may not care – after all, no locking is required.  Even if you do have multiple threads, if a collection is “load-once, read-many” you don’t need to do anything to protect that container from multi-threaded access, as illustrated below: 1: public static class OrderTypeTranslator 2: { 3: // because this dictionary is loaded once before it is ever accessed, we don't need to synchronize 4: // multi-threaded read access 5: private static readonly Dictionary<string, char> _translator = new Dictionary<string, char> 6: { 7: {"New", 'N'}, 8: {"Update", 'U'}, 9: {"Cancel", 'X'} 10: }; 11:  12: // the only public interface into the dictionary is for reading, so inherently thread-safe 13: public static char? Translate(string orderType) 14: { 15: char charValue; 16: if (_translator.TryGetValue(orderType, out charValue)) 17: { 18: return charValue; 19: } 20:  21: return null; 22: } 23: } Unfortunately, most of our computer science problems cannot get by with just single-threaded applications or with multi-threading in a load-once manner.  Looking at  today's trends, it's clear to see that computers are not so much getting faster because of faster processor speeds -- we've nearly reached the limits we can push through with today's technologies -- but more because we're adding more cores to the boxes.  With this new hardware paradigm, it is even more important to use multi-threaded applications to take full advantage of parallel processing to achieve higher application speeds. So let's look at how to use collections in a thread-safe manner. Using historical collections in a concurrent fashion The early .NET collections (System.Collections) had a Synchronized() static method that could be used to wrap the early collections to make them completely thread-safe.  This paradigm was dropped in the generic collections (System.Collections.Generic) because having a synchronized wrapper resulted in atomic locks for all operations, which could prove overkill in many multithreading situations.  Thus the paradigm shifted to having the user of the collection specify their own locking, usually with an external object: 1: public class OrderAggregator 2: { 3: private static readonly Dictionary<string, List<Order>> _orders = new Dictionary<string, List<Order>>(); 4: private static readonly _orderLock = new object(); 5:  6: public void Add(string accountNumber, Order newOrder) 7: { 8: List<Order> ordersForAccount; 9:  10: // a complex operation like this should all be protected 11: lock (_orderLock) 12: { 13: if (!_orders.TryGetValue(accountNumber, out ordersForAccount)) 14: { 15: _orders.Add(accountNumber, ordersForAccount = new List<Order>()); 16: } 17:  18: ordersForAccount.Add(newOrder); 19: } 20: } 21: } Notice how we’re performing several operations on the dictionary under one lock.  With the Synchronized() static methods of the early collections, you wouldn’t be able to specify this level of locking (a more macro-level).  So in the generic collections, it was decided that if a user needed synchronization, they could implement their own locking scheme instead so that they could provide synchronization as needed. The need for better concurrent access to collections Here’s the problem: it’s relatively easy to write a collection that locks itself down completely for access, but anything more complex than that can be difficult and error-prone to write, and much less to make it perform efficiently!  For example, what if you have a Dictionary that has frequent reads but in-frequent updates?  Do you want to lock down the entire Dictionary for every access?  This would be overkill and would prevent concurrent reads.  In such cases you could use something like a ReaderWriterLockSlim which allows for multiple readers in a lock, and then once a writer grabs the lock it blocks all further readers until the writer is done (in a nutshell).  This is all very complex stuff to consider. Fortunately, this is where the Concurrent Collections come in.  The Parallel Computing Platform team at Microsoft went through great pains to determine how to make a set of concurrent collections that would have the best performance characteristics for general case multi-threaded use. Now, as in all things involving threading, you should always make sure you evaluate all your container options based on the particular usage scenario and the degree of parallelism you wish to acheive. This article should not be taken to understand that these collections are always supperior to the generic collections. Each fills a particular need for a particular situation. Understanding what each container is optimized for is key to the success of your application whether it be single-threaded or multi-threaded. General points to consider with the concurrent collections The MSDN points out that the concurrent collections all support the ICollection interface. However, since the collections are already synchronized, the IsSynchronized property always returns false, and SyncRoot always returns null.  Thus you should not attempt to use these properties for synchronization purposes. Note that since the concurrent collections also may have different operations than the traditional data structures you may be used to.  Now you may ask why they did this, but it was done out of necessity to keep operations safe and atomic.  For example, in order to do a Pop() on a stack you have to know the stack is non-empty, but between the time you check the stack’s IsEmpty property and then do the Pop() another thread may have come in and made the stack empty!  This is why some of the traditional operations have been changed to make them safe for concurrent use. In addition, some properties and methods in the concurrent collections achieve concurrency by creating a snapshot of the collection, which means that some operations that were traditionally O(1) may now be O(n) in the concurrent models.  I’ll try to point these out as we talk about each collection so you can be aware of any potential performance impacts.  Finally, all the concurrent containers are safe for enumeration even while being modified, but some of the containers support this in different ways (snapshot vs. dirty iteration).  Once again I’ll highlight how thread-safe enumeration works for each collection. ConcurrentStack<T>: The thread-safe LIFO container The ConcurrentStack<T> is the thread-safe counterpart to the System.Collections.Generic.Stack<T>, which as you may remember is your standard last-in-first-out container.  If you think of algorithms that favor stack usage (for example, depth-first searches of graphs and trees) then you can see how using a thread-safe stack would be of benefit. The ConcurrentStack<T> achieves thread-safe access by using System.Threading.Interlocked operations.  This means that the multi-threaded access to the stack requires no traditional locking and is very, very fast! For the most part, the ConcurrentStack<T> behaves like it’s Stack<T> counterpart with a few differences: Pop() was removed in favor of TryPop() Returns true if an item existed and was popped and false if empty. PushRange() and TryPopRange() were added Allows you to push multiple items and pop multiple items atomically. Count takes a snapshot of the stack and then counts the items. This means it is a O(n) operation, if you just want to check for an empty stack, call IsEmpty instead which is O(1). ToArray() and GetEnumerator() both also take snapshots. This means that iteration over a stack will give you a static view at the time of the call and will not reflect updates. Pushing on a ConcurrentStack<T> works just like you’d expect except for the aforementioned PushRange() method that was added to allow you to push a range of items concurrently. 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: // but you can also push multiple items in one atomic operation (no interleaves) 7: stack.PushRange(new [] { "Second", "Third", "Fourth" }); For looking at the top item of the stack (without removing it) the Peek() method has been removed in favor of a TryPeek().  This is because in order to do a peek the stack must be non-empty, but between the time you check for empty and the time you execute the peek the stack contents may have changed.  Thus the TryPeek() was created to be an atomic check for empty, and then peek if not empty: 1: // to look at top item of stack without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (stack.TryPeek(out item)) 5: { 6: Console.WriteLine("Top item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Stack was empty."); 11: } Finally, to remove items from the stack, we have the TryPop() for single, and TryPopRange() for multiple items.  Just like the TryPeek(), these operations replace Pop() since we need to ensure atomically that the stack is non-empty before we pop from it: 1: // to remove items, use TryPop or TryPopRange to get multiple items atomically (no interleaves) 2: if (stack.TryPop(out item)) 3: { 4: Console.WriteLine("Popped " + item); 5: } 6:  7: // TryPopRange will only pop up to the number of spaces in the array, the actual number popped is returned. 8: var poppedItems = new string[2]; 9: int numPopped = stack.TryPopRange(poppedItems); 10:  11: foreach (var theItem in poppedItems.Take(numPopped)) 12: { 13: Console.WriteLine("Popped " + theItem); 14: } Finally, note that as stated before, GetEnumerator() and ToArray() gets a snapshot of the data at the time of the call.  That means if you are enumerating the stack you will get a snapshot of the stack at the time of the call.  This is illustrated below: 1: var stack = new ConcurrentStack<string>(); 2:  3: // adding to stack is much the same as before 4: stack.Push("First"); 5:  6: var results = stack.GetEnumerator(); 7:  8: // but you can also push multiple items in one atomic operation (no interleaves) 9: stack.PushRange(new [] { "Second", "Third", "Fourth" }); 10:  11: while(results.MoveNext()) 12: { 13: Console.WriteLine("Stack only has: " + results.Current); 14: } The only item that will be printed out in the above code is "First" because the snapshot was taken before the other items were added. This may sound like an issue, but it’s really for safety and is more correct.  You don’t want to enumerate a stack and have half a view of the stack before an update and half a view of the stack after an update, after all.  In addition, note that this is still thread-safe, whereas iterating through a non-concurrent collection while updating it in the old collections would cause an exception. ConcurrentQueue<T>: The thread-safe FIFO container The ConcurrentQueue<T> is the thread-safe counterpart of the System.Collections.Generic.Queue<T> class.  The concurrent queue uses an underlying list of small arrays and lock-free System.Threading.Interlocked operations on the head and tail arrays.  Once again, this allows us to do thread-safe operations without the need for heavy locks! The ConcurrentQueue<T> (like the ConcurrentStack<T>) has some departures from the non-concurrent counterpart.  Most notably: Dequeue() was removed in favor of TryDequeue(). Returns true if an item existed and was dequeued and false if empty. Count does not take a snapshot It subtracts the head and tail index to get the count.  This results overall in a O(1) complexity which is quite good.  It’s still recommended, however, that for empty checks you call IsEmpty instead of comparing Count to zero. ToArray() and GetEnumerator() both take snapshots. This means that iteration over a queue will give you a static view at the time of the call and will not reflect updates. The Enqueue() method on the ConcurrentQueue<T> works much the same as the generic Queue<T>: 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5: queue.Enqueue("Second"); 6: queue.Enqueue("Third"); For front item access, the TryPeek() method must be used to attempt to see the first item if the queue.  There is no Peek() method since, as you’ll remember, we can only peek on a non-empty queue, so we must have an atomic TryPeek() that checks for empty and then returns the first item if the queue is non-empty. 1: // to look at first item in queue without removing it, can use TryPeek. 2: // Note that there is no Peek(), this is because you need to check for empty first. TryPeek does. 3: string item; 4: if (queue.TryPeek(out item)) 5: { 6: Console.WriteLine("First item was " + item); 7: } 8: else 9: { 10: Console.WriteLine("Queue was empty."); 11: } Then, to remove items you use TryDequeue().  Once again this is for the same reason we have TryPeek() and not Peek(): 1: // to remove items, use TryDequeue. If queue is empty returns false. 2: if (queue.TryDequeue(out item)) 3: { 4: Console.WriteLine("Dequeued first item " + item); 5: } Just like the concurrent stack, the ConcurrentQueue<T> takes a snapshot when you call ToArray() or GetEnumerator() which means that subsequent updates to the queue will not be seen when you iterate over the results.  Thus once again the code below will only show the first item, since the other items were added after the snapshot. 1: var queue = new ConcurrentQueue<string>(); 2:  3: // adding to queue is much the same as before 4: queue.Enqueue("First"); 5:  6: var iterator = queue.GetEnumerator(); 7:  8: queue.Enqueue("Second"); 9: queue.Enqueue("Third"); 10:  11: // only shows First 12: while (iterator.MoveNext()) 13: { 14: Console.WriteLine("Dequeued item " + iterator.Current); 15: } Using collections concurrently You’ll notice in the examples above I stuck to using single-threaded examples so as to make them deterministic and the results obvious.  Of course, if we used these collections in a truly multi-threaded way the results would be less deterministic, but would still be thread-safe and with no locking on your part required! For example, say you have an order processor that takes an IEnumerable<Order> and handles each other in a multi-threaded fashion, then groups the responses together in a concurrent collection for aggregation.  This can be done easily with the TPL’s Parallel.ForEach(): 1: public static IEnumerable<OrderResult> ProcessOrders(IEnumerable<Order> orderList) 2: { 3: var proxy = new OrderProxy(); 4: var results = new ConcurrentQueue<OrderResult>(); 5:  6: // notice that we can process all these in parallel and put the results 7: // into our concurrent collection without needing any external locking! 8: Parallel.ForEach(orderList, 9: order => 10: { 11: var result = proxy.PlaceOrder(order); 12:  13: results.Enqueue(result); 14: }); 15:  16: return results; 17: } Summary Obviously, if you do not need multi-threaded safety, you don’t need to use these collections, but when you do need multi-threaded collections these are just the ticket! The plethora of features (I always think of the movie The Three Amigos when I say plethora) built into these containers and the amazing way they acheive thread-safe access in an efficient manner is wonderful to behold. Stay tuned next week where we’ll continue our discussion with the ConcurrentBag<T> and the ConcurrentDictionary<TKey,TValue>. For some excellent information on the performance of the concurrent collections and how they perform compared to a traditional brute-force locking strategy, see this wonderful whitepaper by the Microsoft Parallel Computing Platform team here.   Tweet Technorati Tags: C#,.NET,Concurrent Collections,Collections,Multi-Threading,Little Wonders,BlackRabbitCoder,James Michael Hare

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  • Extending NerdDinner: Adding Geolocated Flair

    - by Jon Galloway
    NerdDinner is a website with the audacious goal of “Organizing the world’s nerds and helping them eat in packs.” Because nerds aren’t likely to socialize with others unless a website tells them to do it. Scott Hanselman showed off a lot of the cool features we’ve added to NerdDinner lately during his popular talk at MIX10, Beyond File | New Company: From Cheesy Sample to Social Platform. Did you miss it? Go ahead and watch it, I’ll wait. One of the features we wanted to add was flair. You know about flair, right? It’s a way to let folks who like your site show it off in their own site. For example, here’s my StackOverflow flair: Great! So how could we add some of this flair stuff to NerdDinner? What do we want to show? If we’re going to encourage our users to give up a bit of their beautiful website to show off a bit of ours, we need to think about what they’ll want to show. For instance, my StackOverflow flair is all about me, not StackOverflow. So how will this apply to NerdDinner? Since NerdDinner is all about organizing local dinners, in order for the flair to be useful it needs to make sense for the person viewing the web page. If someone visits from Egypt visits my blog, they should see information about NerdDinners in Egypt. That’s geolocation – localizing site content based on where the browser’s sitting, and it makes sense for flair as well as entire websites. So we’ll set up a simple little callout that prompts them to host a dinner in their area: Hopefully our flair works and there is a dinner near your viewers, so they’ll see another view which lists upcoming dinners near them: The Geolocation Part Generally website geolocation is done by mapping the requestor’s IP address to a geographic area. It’s not an exact science, but I’ve always found it to be pretty accurate. There are (at least) three ways to handle it: You pay somebody like MaxMind for a database (with regular updates) that sits on your server, and you use their API to do lookups. I used this on a pretty big project a few years ago and it worked well. You use HTML 5 Geolocation API or Google Gears or some other browser based solution. I think those are cool (I use Google Gears a lot), but they’re both in flux right now and I don’t think either has a wide enough of an install base yet to rely on them. You might want to, but I’ve heard you do all kinds of crazy stuff, and sometimes it gets you in trouble. I don’t mean talk out of line, but we all laugh behind your back a bit. But, hey, it’s up to you. It’s your flair or whatever. There are some free webservices out there that will take an IP address and give you location information. Easy, and works for everyone. That’s what we’re doing. I looked at a few different services and settled on IPInfoDB. It’s free, has a great API, and even returns JSON, which is handy for Javascript use. The IP query is pretty simple. We hit a URL like this: http://ipinfodb.com/ip_query.php?ip=74.125.45.100&timezone=false … and we get an XML response back like this… <?xml version="1.0" encoding="UTF-8"?> <Response> <Ip>74.125.45.100</Ip> <Status>OK</Status> <CountryCode>US</CountryCode> <CountryName>United States</CountryName> <RegionCode>06</RegionCode> <RegionName>California</RegionName> <City>Mountain View</City> <ZipPostalCode>94043</ZipPostalCode> <Latitude>37.4192</Latitude> <Longitude>-122.057</Longitude> </Response> So we’ll build some data transfer classes to hold the location information, like this: public class LocationInfo { public string Country { get; set; } public string RegionName { get; set; } public string City { get; set; } public string ZipPostalCode { get; set; } public LatLong Position { get; set; } } public class LatLong { public float Lat { get; set; } public float Long { get; set; } } And now hitting the service is pretty simple: public static LocationInfo HostIpToPlaceName(string ip) { string url = "http://ipinfodb.com/ip_query.php?ip={0}&timezone=false"; url = String.Format(url, ip); var result = XDocument.Load(url); var location = (from x in result.Descendants("Response") select new LocationInfo { City = (string)x.Element("City"), RegionName = (string)x.Element("RegionName"), Country = (string)x.Element("CountryName"), ZipPostalCode = (string)x.Element("CountryName"), Position = new LatLong { Lat = (float)x.Element("Latitude"), Long = (float)x.Element("Longitude") } }).First(); return location; } Getting The User’s IP Okay, but first we need the end user’s IP, and you’d think it would be as simple as reading the value from HttpContext: HttpContext.Current.Request.UserHostAddress But you’d be wrong. Sorry. UserHostAddress just wraps HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"], but that doesn’t get you the IP for users behind a proxy. That’s in another header, “HTTP_X_FORWARDED_FOR". So you can either hit a wrapper and then check a header, or just check two headers. I went for uniformity: string SourceIP = string.IsNullOrEmpty(Request.ServerVariables["HTTP_X_FORWARDED_FOR"]) ? Request.ServerVariables["REMOTE_ADDR"] : Request.ServerVariables["HTTP_X_FORWARDED_FOR"]; We’re almost set to wrap this up, but first let’s talk about our views. Yes, views, because we’ll have two. Selecting the View We wanted to make it easy for people to include the flair in their sites, so we looked around at how other people were doing this. The StackOverflow folks have a pretty good flair system, which allows you to include the flair in your site as either an IFRAME reference or a Javascript include. We’ll do both. We have a ServicesController to handle use of the site information outside of NerdDinner.com, so this fits in pretty well there. We’ll be displaying the same information for both HTML and Javascript flair, so we can use one Flair controller action which will return a different view depending on the requested format. Here’s our general flow for our controller action: Get the user’s IP Translate it to a location Grab the top three upcoming dinners that are near that location Select the view based on the format (defaulted to “html”) Return a FlairViewModel which contains the list of dinners and the location information public ActionResult Flair(string format = "html") { string SourceIP = string.IsNullOrEmpty( Request.ServerVariables["HTTP_X_FORWARDED_FOR"]) ? Request.ServerVariables["REMOTE_ADDR"] : Request.ServerVariables["HTTP_X_FORWARDED_FOR"]; var location = GeolocationService.HostIpToPlaceName(SourceIP); var dinners = dinnerRepository. FindByLocation(location.Position.Lat, location.Position.Long). OrderByDescending(p => p.EventDate).Take(3); // Select the view we'll return. // Using a switch because we'll add in JSON and other formats later. string view; switch (format.ToLower()) { case "javascript": view = "JavascriptFlair"; break; default: view = "Flair"; break; } return View( view, new FlairViewModel { Dinners = dinners.ToList(), LocationName = string.IsNullOrEmpty(location.City) ? "you" : String.Format("{0}, {1}", location.City, location.RegionName) } ); } Note: I’m not in love with the logic here, but it seems like overkill to extract the switch statement away when we’ll probably just have two or three views. What do you think? The HTML View The HTML version of the view is pretty simple – the only thing of any real interest here is the use of an extension method to truncate strings that are would cause the titles to wrap. public static string Truncate(this string s, int maxLength) { if (string.IsNullOrEmpty(s) || maxLength <= 0) return string.Empty; else if (s.Length > maxLength) return s.Substring(0, maxLength) + "..."; else return s; }   So here’s how the HTML view ends up looking: <%@ Page Title="" Language="C#" Inherits="System.Web.Mvc.ViewPage<FlairViewModel>" %> <%@ Import Namespace="NerdDinner.Helpers" %> <%@ Import Namespace="NerdDinner.Models" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Nerd Dinner</title> <link href="/Content/Flair.css" rel="stylesheet" type="text/css" /> </head> <body> <div id="nd-wrapper"> <h2 id="nd-header">NerdDinner.com</h2> <div id="nd-outer"> <% if (Model.Dinners.Count == 0) { %> <div id="nd-bummer"> Looks like there's no Nerd Dinners near <%:Model.LocationName %> in the near future. Why not <a target="_blank" href="http://www.nerddinner.com/Dinners/Create">host one</a>?</div> <% } else { %> <h3> Dinners Near You</h3> <ul> <% foreach (var item in Model.Dinners) { %> <li> <%: Html.ActionLink(String.Format("{0} with {1} on {2}", item.Title.Truncate(20), item.HostedBy, item.EventDate.ToShortDateString()), "Details", "Dinners", new { id = item.DinnerID }, new { target = "_blank" })%></li> <% } %> </ul> <% } %> <div id="nd-footer"> More dinners and fun at <a target="_blank" href="http://nrddnr.com">http://nrddnr.com</a></div> </div> </div> </body> </html> You’d include this in a page using an IFRAME, like this: <IFRAME height=230 marginHeight=0 src="http://nerddinner.com/services/flair" frameBorder=0 width=160 marginWidth=0 scrolling=no></IFRAME> The Javascript view The Javascript flair is written so you can include it in a webpage with a simple script include, like this: <script type="text/javascript" src="http://nerddinner.com/services/flair?format=javascript"></script> The goal of this view is very similar to the HTML embed view, with a few exceptions: We’re creating a script element and adding it to the head of the document, which will then document.write out the content. Note that you have to consider if your users will actually have a <head> element in their documents, but for website flair use cases I think that’s a safe bet. Since the content is being added to the existing page rather than shown in an IFRAME, all links need to be absolute. That means we can’t use Html.ActionLink, since it generates relative routes. We need to escape everything since it’s being written out as strings. We need to set the content type to application/x-javascript. The easiest way to do that is to use the <%@ Page ContentType%> directive. <%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<NerdDinner.Models.FlairViewModel>" ContentType="application/x-javascript" %> <%@ Import Namespace="NerdDinner.Helpers" %> <%@ Import Namespace="NerdDinner.Models" %> document.write('<script>var link = document.createElement(\"link\");link.href = \"http://nerddinner.com/content/Flair.css\";link.rel = \"stylesheet\";link.type = \"text/css\";var head = document.getElementsByTagName(\"head\")[0];head.appendChild(link);</script>'); document.write('<div id=\"nd-wrapper\"><h2 id=\"nd-header\">NerdDinner.com</h2><div id=\"nd-outer\">'); <% if (Model.Dinners.Count == 0) { %> document.write('<div id=\"nd-bummer\">Looks like there\'s no Nerd Dinners near <%:Model.LocationName %> in the near future. Why not <a target=\"_blank\" href=\"http://www.nerddinner.com/Dinners/Create\">host one</a>?</div>'); <% } else { %> document.write('<h3> Dinners Near You</h3><ul>'); <% foreach (var item in Model.Dinners) { %> document.write('<li><a target=\"_blank\" href=\"http://nrddnr.com/<%: item.DinnerID %>\"><%: item.Title.Truncate(20) %> with <%: item.HostedBy %> on <%: item.EventDate.ToShortDateString() %></a></li>'); <% } %> document.write('</ul>'); <% } %> document.write('<div id=\"nd-footer\"> More dinners and fun at <a target=\"_blank\" href=\"http://nrddnr.com\">http://nrddnr.com</a></div></div></div>'); Getting IP’s for Testing There are a variety of online services that will translate a location to an IP, which were handy for testing these out. I found http://www.itouchmap.com/latlong.html to be most useful, but I’m open to suggestions if you know of something better. Next steps I think the next step here is to minimize load – you know, in case people start actually using this flair. There are two places to think about – the NerdDinner.com servers, and the services we’re using for Geolocation. I usually think about caching as a first attack on server load, but that’s less helpful here since every user will have a different IP. Instead, I’d look at taking advantage of Asynchronous Controller Actions, a cool new feature in ASP.NET MVC 2. Async Actions let you call a potentially long-running webservice without tying up a thread on the server while waiting for the response. There’s some good info on that in the MSDN documentation, and Dino Esposito wrote a great article on Asynchronous ASP.NET Pages in the April 2010 issue of MSDN Magazine. But let’s think of the children, shall we? What about ipinfodb.com? Well, they don’t have specific daily limits, but they do throttle you if you put a lot of traffic on them. From their FAQ: We do not have a specific daily limit but queries that are at a rate faster than 2 per second will be put in "queue". If you stay below 2 queries/second everything will be normal. If you go over the limit, you will still get an answer for all queries but they will be slowed down to about 1 per second. This should not affect most users but for high volume websites, you can either use our IP database on your server or we can whitelist your IP for 5$/month (simply use the donate form and leave a comment with your server IP). Good programming practices such as not querying our API for all page views (you can store the data in a cookie or a database) will also help not reaching the limit. So the first step there is to save the geolocalization information in a time-limited cookie, which will allow us to look up the local dinners immediately without having to hit the geolocation service.

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  • Microsoft Introduces WebMatrix

    - by Rick Strahl
    originally published in CoDe Magazine Editorial Microsoft recently released the first CTP of a new development environment called WebMatrix, which along with some of its supporting technologies are squarely aimed at making the Microsoft Web Platform more approachable for first-time developers and hobbyists. But in the process, it also provides some updated technologies that can make life easier for existing .NET developers. Let’s face it: ASP.NET development isn’t exactly trivial unless you already have a fair bit of familiarity with sophisticated development practices. Stick a non-developer in front of Visual Studio .NET or even the Visual Web Developer Express edition and it’s not likely that the person in front of the screen will be very productive or feel inspired. Yet other technologies like PHP and even classic ASP did provide the ability for non-developers and hobbyists to become reasonably proficient in creating basic web content quickly and efficiently. WebMatrix appears to be Microsoft’s attempt to bring back some of that simplicity with a number of technologies and tools. The key is to provide a friendly and fully self-contained development environment that provides all the tools needed to build an application in one place, as well as tools that allow publishing of content and databases easily to the web server. WebMatrix is made up of several components and technologies: IIS Developer Express IIS Developer Express is a new, self-contained development web server that is fully compatible with IIS 7.5 and based on the same codebase that IIS 7.5 uses. This new development server replaces the much less compatible Cassini web server that’s been used in Visual Studio and the Express editions. IIS Express addresses a few shortcomings of the Cassini server such as the inability to serve custom ISAPI extensions (i.e., things like PHP or ASP classic for example), as well as not supporting advanced authentication. IIS Developer Express provides most of the IIS 7.5 feature set providing much better compatibility between development and live deployment scenarios. SQL Server Compact 4.0 Database access is a key component for most web-driven applications, but on the Microsoft stack this has mostly meant you have to use SQL Server or SQL Server Express. SQL Server Compact is not new-it’s been around for a few years, but it’s been severely hobbled in the past by terrible tool support and the inability to support more than a single connection in Microsoft’s attempt to avoid losing SQL Server licensing. The new release of SQL Server Compact 4.0 supports multiple connections and you can run it in ASP.NET web applications simply by installing an assembly into the bin folder of the web application. In effect, you don’t have to install a special system configuration to run SQL Compact as it is a drop-in database engine: Copy the small assembly into your BIN folder (or from the GAC if installed fully), create a connection string against a local file-based database file, and then start firing SQL requests. Additionally WebMatrix includes nice tools to edit the database tables and files, along with tools to easily upsize (and hopefully downsize in the future) to full SQL Server. This is a big win, pending compatibility and performance limits. In my simple testing the data engine performed well enough for small data sets. This is not only useful for web applications, but also for desktop applications for which a fully installed SQL engine like SQL Server would be overkill. Having a local data store in those applications that can potentially be accessed by multiple users is a welcome feature. ASP.NET Razor View Engine What? Yet another native ASP.NET view engine? We already have Web Forms and various different flavors of using that view engine with Web Forms and MVC. Do we really need another? Microsoft thinks so, and Razor is an implementation of a lightweight, script-only view engine. Unlike the Web Forms view engine, Razor works only with inline code, snippets, and markup; therefore, it is more in line with current thinking of what a view engine should represent. There’s no support for a “page model” or any of the other Web Forms features of the full-page framework, but just a lightweight scripting engine that works with plain markup plus embedded expressions and code. The markup syntax for Razor is geared for minimal typing, plus some progressive detection of where a script block/expression starts and ends. This results in a much leaner syntax than the typical ASP.NET Web Forms alligator (<% %>) tags. Razor uses the @ sign plus standard C# (or Visual Basic) block syntax to delineate code snippets and expressions. Here’s a very simple example of what Razor markup looks like along with some comment annotations: <!DOCTYPE html> <html>     <head>         <title></title>     </head>     <body>     <h1>Razor Test</h1>          <!-- simple expressions -->     @DateTime.Now     <hr />     <!-- method expressions -->     @DateTime.Now.ToString("T")          <!-- code blocks -->     @{         List<string> names = new List<string>();         names.Add("Rick");         names.Add("Markus");         names.Add("Claudio");         names.Add("Kevin");     }          <!-- structured block statements -->     <ul>     @foreach(string name in names){             <li>@name</li>     }     </ul>           <!-- Conditional code -->        @if(true) {                        <!-- Literal Text embedding in code -->        <text>         true        </text>;    }    else    {        <!-- Literal Text embedding in code -->       <text>       false       </text>;    }    </body> </html> Like the Web Forms view engine, Razor parses pages into code, and then executes that run-time compiled code. Effectively a “page” becomes a code file with markup becoming literal text written into the Response stream, code snippets becoming raw code, and expressions being written out with Response.Write(). The code generated from Razor doesn’t look much different from similar Web Forms code that only uses script tags; so although the syntax may look different, the operational model is fairly similar to the Web Forms engine minus the overhead of the large Page object model. However, there are differences: -Razor pages are based on a new base class, Microsoft.WebPages.WebPage, which is hosted in the Microsoft.WebPages assembly that houses all the Razor engine parsing and processing logic. Browsing through the assembly (in the generated ASP.NET Temporary Files folder or GAC) will give you a good idea of the functionality that Razor provides. If you look closely, a lot of the feature set matches ASP.NET MVC’s view implementation as well as many of the helper classes found in MVC. It’s not hard to guess the motivation for this sort of view engine: For beginning developers the simple markup syntax is easier to work with, although you obviously still need to have some understanding of the .NET Framework in order to create dynamic content. The syntax is easier to read and grok and much shorter to type than ASP.NET alligator tags (<% %>) and also easier to understand aesthetically what’s happening in the markup code. Razor also is a better fit for Microsoft’s vision of ASP.NET MVC: It’s a new view engine without the baggage of Web Forms attached to it. The engine is more lightweight since it doesn’t carry all the features and object model of Web Forms with it and it can be instantiated directly outside of the HTTP environment, which has been rather tricky to do for the Web Forms view engine. Having a standalone script parser is a huge win for other applications as well – it makes it much easier to create script or meta driven output generators for many types of applications from code/screen generators, to simple form letters to data merging applications with user customizability. For me personally this is very useful side effect and who knows maybe Microsoft will actually standardize they’re scripting engines (die T4 die!) on this engine. Razor also better fits the “view-based” approach where the view is supposed to be mostly a visual representation that doesn’t hold much, if any, code. While you can still use code, the code you do write has to be self-contained. Overall I wouldn’t be surprised if Razor will become the new standard view engine for MVC in the future – and in fact there have been announcements recently that Razor will become the default script engine in ASP.NET MVC 3.0. Razor can also be used in existing Web Forms and MVC applications, although that’s not working currently unless you manually configure the script mappings and add the appropriate assemblies. It’s possible to do it, but it’s probably better to wait until Microsoft releases official support for Razor scripts in Visual Studio. Once that happens, you can simply drop .cshtml and .vbhtml pages into an existing ASP.NET project and they will work side by side with classic ASP.NET pages. WebMatrix Development Environment To tie all of these three technologies together, Microsoft is shipping WebMatrix with an integrated development environment. An integrated gallery manager makes it easy to download and load existing projects, and then extend them with custom functionality. It seems to be a prominent goal to provide community-oriented content that can act as a starting point, be it via a custom templates or a complete standard application. The IDE includes a project manager that works with a single project and provides an integrated IDE/editor for editing the .cshtml and .vbhtml pages. A run button allows you to quickly run pages in the project manager in a variety of browsers. There’s no debugging support for code at this time. Note that Razor pages don’t require explicit compilation, so making a change, saving, and then refreshing your page in the browser is all that’s needed to see changes while testing an application locally. It’s essentially using the auto-compiling Web Project that was introduced with .NET 2.0. All code is compiled during run time into dynamically created assemblies in the ASP.NET temp folder. WebMatrix also has PHP Editing support with syntax highlighting. You can load various PHP-based applications from the WebMatrix Web Gallery directly into the IDE. Most of the Web Gallery applications are ready to install and run without further configuration, with Wizards taking you through installation of tools, dependencies, and configuration of the database as needed. WebMatrix leverages the Web Platform installer to pull the pieces down from websites in a tight integration of tools that worked nicely for the four or five applications I tried this out on. Click a couple of check boxes and fill in a few simple configuration options and you end up with a running application that’s ready to be customized. Nice! You can easily deploy completed applications via WebDeploy (to an IIS server) or FTP directly from within the development environment. The deploy tool also can handle automatically uploading and installing the database and all related assemblies required, making deployment a simple one-click install step. Simplified Database Access The IDE contains a database editor that can edit SQL Compact and SQL Server databases. There is also a Database helper class that facilitates database access by providing easy-to-use, high-level query execution and iteration methods: @{       var db = Database.OpenFile("FirstApp.sdf");     string sql = "select * from customers where Id > @0"; } <ul> @foreach(var row in db.Query(sql,1)){         <li>@row.FirstName @row.LastName</li> } </ul> The query function takes a SQL statement plus any number of positional (@0,@1 etc.) SQL parameters by simple values. The result is returned as a collection of rows which in turn have a row object with dynamic properties for each of the columns giving easy (though untyped) access to each of the fields. Likewise Execute and ExecuteNonQuery allow execution of more complex queries using similar parameter passing schemes. Note these queries use string-based queries rather than LINQ or Entity Framework’s strongly typed LINQ queries. While this may seem like a step back, it’s also in line with the expectations of non .NET script developers who are quite used to writing and using SQL strings in code rather than using OR/M frameworks. The only question is why was something not included from the beginning in .NET and Microsoft made developers build custom implementations of these basic building blocks. The implementation looks a lot like a DataTable-style data access mechanism, but to be fair, this is a common approach in scripting languages. This type of syntax that uses simple, static, data object methods to perform simple data tasks with one line of code are common in scripting languages and are a good match for folks working in PHP/Python, etc. Seems like Microsoft has taken great advantage of .NET 4.0’s dynamic typing to provide this sort of interface for row iteration where each row has properties for each field. FWIW, all the examples demonstrate using local SQL Compact files - I was unable to get a SQL Server connection string to work with the Database class (the connection string wasn’t accepted). However, since the code in the page is still plain old .NET, you can easily use standard ADO.NET code or even LINQ or Entity Framework models that are created outside of WebMatrix in separate assemblies as required. The good the bad the obnoxious - It’s still .NET The beauty (or curse depending on how you look at it :)) of Razor and the compilation model is that, behind it all, it’s still .NET. Although the syntax may look foreign, it’s still all .NET behind the scenes. You can easily access existing tools, helpers, and utilities simply by adding them to the project as references or to the bin folder. Razor automatically recognizes any assembly reference from assemblies in the bin folder. In the default configuration, Microsoft provides a host of helper functions in a Microsoft.WebPages assembly (check it out in the ASP.NET temp folder for your application), which includes a host of HTML Helpers. If you’ve used ASP.NET MVC before, a lot of the helpers should look familiar. Documentation at the moment is sketchy-there’s a very rough API reference you can check out here: http://www.asp.net/webmatrix/tutorials/asp-net-web-pages-api-reference Who needs WebMatrix? Uhm… good Question Clearly Microsoft is trying hard to create an environment with WebMatrix that is easy to use for newbie developers. The goal seems to be simplicity in providing a minimal development environment and an easy-to-use script engine/language that makes it easy to get started with. There’s also some focus on community features that can be used as starting points, such as Web Gallery applications and templates. The community features in particular are very nice and something that would be nice to eventually see in Visual Studio as well. The question is whether this is too little too late. Developers who have been clamoring for a simpler development environment on the .NET stack have mostly left for other simpler platforms like PHP or Python which are catering to the down and dirty developer. Microsoft will be hard pressed to win those folks-and other hardcore PHP developers-back. Regardless of how much you dress up a script engine fronted by the .NET Framework, it’s still the .NET Framework and all the complexity that drives it. While .NET is a fine solution in its breadth and features once you get a basic handle on the core features, the bar of entry to being productive with the .NET Framework is still pretty high. The MVC style helpers Microsoft provides are a good step in the right direction, but I suspect it’s not enough to shield new developers from having to delve much deeper into the Framework to get even basic applications built. Razor and its helpers is trying to make .NET more accessible but the reality is that in order to do useful stuff that goes beyond the handful of simple helpers you still are going to have to write some C# or VB or other .NET code. If the target is a hobby/amateur/non-programmer the learning curve isn’t made any easier by WebMatrix it’s just been shifted a tad bit further along in your development endeavor when you run out of canned components that are supplied either by Microsoft or the community. The database helpers are interesting and actually I’ve heard a lot of discussion from various developers who’ve been resisting .NET for a really long time perking up at the prospect of easier data access in .NET than the ridiculous amount of code it takes to do even simple data access with raw ADO.NET. It seems sad that such a simple concept and implementation should trigger this sort of response (especially since it’s practically trivial to create helpers like these or pick them up from countless libraries available), but there it is. It also shows that there are plenty of developers out there who are more interested in ‘getting stuff done’ easily than necessarily following the latest and greatest practices which are overkill for many development scenarios. Sometimes it seems that all of .NET is focused on the big life changing issues of development, rather than the bread and butter scenarios that many developers are interested in to get their work accomplished. And that in the end may be WebMatrix’s main raison d'être: To bring some focus back at Microsoft that simpler and more high level solutions are actually needed to appeal to the non-high end developers as well as providing the necessary tools for the high end developers who want to follow the latest and greatest trends. The current version of WebMatrix hits many sweet spots, but it also feels like it has a long way to go before it really can be a tool that a beginning developer or an accomplished developer can feel comfortable with. Although there are some really good ideas in the environment (like the gallery for downloading apps and components) which would be a great addition for Visual Studio as well, the rest of the development environment just feels like crippleware with required functionality missing especially debugging and Intellisense, but also general editor support. It’s not clear whether these are because the product is still in an early alpha release or whether it’s simply designed that way to be a really limited development environment. While simple can be good, nobody wants to feel left out when it comes to necessary tool support and WebMatrix just has that left out feeling to it. If anything WebMatrix’s technology pieces (which are really independent of the WebMatrix product) are what are interesting to developers in general. The compact IIS implementation is a nice improvement for development scenarios and SQL Compact 4.0 seems to address a lot of concerns that people have had and have complained about for some time with previous SQL Compact implementations. By far the most interesting and useful technology though seems to be the Razor view engine for its light weight implementation and it’s decoupling from the ASP.NET/HTTP pipeline to provide a standalone scripting/view engine that is pluggable. The first winner of this is going to be ASP.NET MVC which can now have a cleaner view model that isn’t inconsistent due to the baggage of non-implemented WebForms features that don’t work in MVC. But I expect that Razor will end up in many other applications as a scripting and code generation engine eventually. Visual Studio integration for Razor is currently missing, but is promised for a later release. The ASP.NET MVC team has already mentioned that Razor will eventually become the default MVC view engine, which will guarantee continued growth and development of this tool along those lines. And the Razor engine and support tools actually inherit many of the features that MVC pioneered, so there’s some synergy flowing both ways between Razor and MVC. As an existing ASP.NET developer who’s already familiar with Visual Studio and ASP.NET development, the WebMatrix IDE doesn’t give you anything that you want. The tools provided are minimal and provide nothing that you can’t get in Visual Studio today, except the minimal Razor syntax highlighting, so there’s little need to take a step back. With Visual Studio integration coming later there’s little reason to look at WebMatrix for tooling. It’s good to see that Microsoft is giving some thought about the ease of use of .NET as a platform For so many years, we’ve been piling on more and more new features without trying to take a step back and see how complicated the development/configuration/deployment process has become. Sometimes it’s good to take a step - or several steps - back and take another look and realize just how far we’ve come. WebMatrix is one of those reminders and one that likely will result in some positive changes on the platform as a whole. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET   IIS7  

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  • Could not resolve <fx:Script> to a component implementation.

    - by seref
    Hi, i created project with flexmojos maven archtype..i used flexmojos:flexbuilder and compile/run with FlashBuilder 4 everything is okay but when i try to compile project with flexmojos i got following error: [ERROR] Z:....\src\main\flex\Main.mxml:[6,-1] Could not resolve < fx:Script to a component implementation. [INFO] BUILD FAILURE my mxml: <?xml version="1.0" encoding="utf-8"?> <s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" xmlns:s="library://ns.adobe.com/flex/spark" xmlns:mx="library://ns.adobe.com/flex/mx" width="100%" height="100%" creationComplete="application1_creationCompleteHandler(event)"> <fx:Script> <![CDATA[ import mx.controls.Alert; import mx.events.FlexEvent; protected function application1_creationCompleteHandler(event:FlexEvent):void { Alert.show("success!!!!") } ]]></fx:Script> </s:Application> pom.xml like: ...... <packaging>swf</packaging> ...... <properties> <flex-sdk.version>4.1.0.16076</flex-sdk.version> <flexmojos.version>3.8</flexmojos.version> </properties> ...... <build> <sourceDirectory>src/main/flex</sourceDirectory> <testSourceDirectory>src/test/flex</testSourceDirectory> <plugins> <plugin> <groupId>org.sonatype.flexmojos</groupId> <artifactId>flexmojos-maven-plugin</artifactId> <version>${flexmojos.version}</version> <extensions>true</extensions> <dependencies> <dependency> <groupId>com.adobe.flex</groupId> <artifactId>compiler</artifactId> <version>${flex-sdk.version}</version> <type>pom</type> </dependency> </dependencies> <configuration> <compiledLocales> <locale>en_US</locale> </compiledLocales> <mergeResourceBundle>true</mergeResourceBundle> <accessible>true</accessible> <optimize>true</optimize> <targetPlayer>10.0.0</targetPlayer> <showWarnings>true</showWarnings> <linkReport>true</linkReport> </configuration> </plugin> </plugins> </build> <dependencies> <!-- Flex framework resource bundles --> <dependency> <groupId>com.adobe.flex.framework</groupId> <artifactId>flex-framework</artifactId> <version>${flex-sdk.version}</version> <type>pom</type> </dependency> <!-- Include unit test dependencies. --> <dependency> <groupId>com.adobe.flexunit</groupId> <artifactId>flexunit</artifactId> <version>4.0-rc-1</version> <type>swc</type> <scope>test</scope> </dependency> </dependencies> ....... maven output compiler config : INFO] Flex compiler configurations: -compiler.external-library-path C:\...\.m2\repository\com\adobe\flex \framework\playerglobal\4.1.0.16076\10.0\playerglobal.swc -compiler.include-libraries= -compiler.library-path C:\...\.m2\repository\com\adobe\flex\framework \datavisualization\4.1.0.16076\datavisualization-4.1.0.16076.swc C:\... \.m2\repository\com\adobe\flex\framework\flash-integration \4.1.0.16076\flash-integration-4.1.0.16076.swc C:\...\.m2\repository \com\adobe\flex\framework\flex\4.1.0.16076\flex-4.1.0.16076.swc C:\... \.m2\repository\com\adobe\flex\framework\framework \4.1.0.16076\framework-4.1.0.16076.swc C:\...\.m2\repository\com\adobe \flex\framework\osmf\4.1.0.16076\osmf-4.1.0.16076.swc C:\... \.m2\repository\com\adobe\flex\framework\rpc \4.1.0.16076\rpc-4.1.0.16076.swc C:\...\.m2\repository\com\adobe\flex \framework\spark\4.1.0.16076\spark-4.1.0.16076.swc C:\... \.m2\repository\com\adobe\flex\framework\sparkskins \4.1.0.16076\sparkskins-4.1.0.16076.swc C:\...\.m2\repository\com\adobe \flex\framework\textLayout\4.1.0.16076\textLayout-4.1.0.16076.swc C: \...\.m2\repository\com\adobe\flex\framework\utilities \4.1.0.16076\utilities-4.1.0.16076.swc C:\...\.m2\repository\com\adobe \flex\framework\datavisualization \4.1.0.16076\datavisualization-4.1.0.16076-en_US.rb.swc C:\... \.m2\repository\com\adobe\flex\framework\framework \4.1.0.16076\framework-4.1.0.16076-en_US.rb.swc C:\...\.m2\repository \com\adobe\flex\framework\osmf\4.1.0.16076\osmf-4.1.0.16076- en_US.rb.swc C:\...\.m2\repository\com\adobe\flex\framework\rpc \4.1.0.16076\rpc-4.1.0.16076-en_US.rb.swc C:\...\.m2\repository\com \adobe\flex\framework\spark\4.1.0.16076\spark-4.1.0.16076-en_US.rb.swc C:\...\.m2\repository\com\adobe\flex\framework\textLayout \4.1.0.16076\textLayout-4.1.0.16076-en_US.rb.swc C:\...\.m2\repository \com\adobe\flex\framework\flash-integration\4.1.0.16076\flash- integration-4.1.0.16076-en_US.rb.swc C:\...\.m2\repository\com\adobe \flex\framework\playerglobal\4.1.0.16076\playerglobal-4.1.0.16076- en_US.rb.swc -compiler.theme Z:\.....\target\classes\configs\themes\Spark \spark.css -compiler.accessible=true -compiler.allow-source-path-overlap=false -compiler.as3=true -compiler.debug=false -compiler.es=false -compiler.fonts.managers flash.fonts.JREFontManager flash.fonts.BatikFontManager flash.fonts.AFEFontManager flash.fonts.CFFFontManager -compiler.fonts.local-fonts-snapshot Z:\.....\target\classes \fonts.ser -compiler.keep-generated-actionscript=false -licenses.license flashbuilder4 952309948800588759250406 -licenses.license flexbuilder4.displayedStartPageAtLeastOneTime true -compiler.locale en_US -compiler.optimize=true -compiler.source-path Z:\.....\src\main\flex -compiler.strict=true -use-network=true -compiler.verbose-stacktraces=false -compiler.actionscript-file-encoding UTF-8 -target-player 10.0.0 -default-background-color 8821927 -default-frame-rate 24 -default-script-limits 1000 60 -default-size 500 375 -compiler.headless-server=false -compiler.keep-all-type-selectors=false -compiler.use-resource-bundle-metadata=true -metadata.date Fri Mar 04 14:04:37 EET 2011 -metadata.localized-title Main x-default -verify-digests=true -compiler.namespaces.namespace+=http://ns.adobe.com/mxml/2009,Z:\..... \target\classes\config-4.1.0.16076\mxml-2009-manifest.xml -compiler.namespaces.namespace+=library://ns.adobe.com/flex/spark,Z: \.....\target\classes\config-4.1.0.16076\spark-manifest.xml -compiler.namespaces.namespace+=library://ns.adobe.com/flex/mx,Z:\..... \target\classes\config-4.1.0.16076\mx-manifest.xml -compiler.namespaces.namespace+=http://www.adobe.com/2006/mxml,Z:\..... \PozitronUI\target\classes\config-4.1.0.16076\mxml-manifest.xml - static-link-runtime-shared-libraries=false -load-config= -metadata.language+=en_US any help... regards,

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  • Impossible to do POSTs with appengine-jruby/RoR: Reflection is not allowed

    - by Joel Cuevas
    I'm trying to build a site with RoR on Google App Engine. I'm using the google-appengine gem (http://appengine-jruby.googlecode.com) and following the instructions in (http://gist.github.com/268192). The problem is that I can't submit ANY form! I've already tried this in two diferent clean Win 7 Pro envs and the result is the same. After install Ruby 1.8.6 (One-Click Installer): 1. gem update --system 2. gem install rails 3. gem install google-appengine 4. gem install rails_dm_datastore 5. gem install activerecord-nulldb-adapter 6. curl -O http://appengine-jruby.googlecode.com/hg/demos/rails2/rails2_appengine.rb 7. ruby rails2_appengine.rb (previously downloaded) 8. rails myproj 9. chmod myproj 10. ruby script/generate dd_model MyModel f1:string f2:float f3:float f4:float f5:integer f6:integer f7:integer -f 11. ruby script/generate scaffold MyModel f1:string f2:float f3:float f4:float f5:integer f6:integer f7:integer -f --skip-migration 12. dev_appserver.rb -p 3000 . At this point, I manually test the scaffold in (http://localhost:3000/my_models). The index is OK, then I create a new registry with the generated form, everything's fine, but when I try to create a second one, I get a "java.lang.RuntimeException: DummyDynamicScope should never be used for backref storage" in the console. As far as I read this is a won't-fix behavior in JRuby 1.4.1, but it's converted to a debug only warning in 1.5.0, so I proceed to install the pre release. 13. gem install appengine-jruby-jars --pre With this, that exception is solved and everything works great... until I move the project to the GAE server. 14. ruby appcfg.rb update . And now, in (http://myproj.appspot.com/my_models), again, the index is fine, also the new form, but in the moment that I submit it with valid data, I get a 500 error: "java.lang.IllegalAccessException: Reflection is not allowed on public int". As I said, this behavior is not present in the local SDK. In both cases, I'm completely unable to post anything. This is what I have right now in the GAE environment: Ruby version 1.8.7 (java) RubyGems disabled Rack version 1.1 Rails version 2.3.5 Action Pack version 2.3.5 Active Support version 2.3.5 DataMapper version 0.10.2 Environment production JRuby Runtime version 1.5.0.pre JRuby-Rack version 0.9.7 AppEngine SDK version Google App Engine/1.3.3 AppEngine APIs version 0.0.15 And this are my intalled gems: actionmailer (2.3.5) actionpack (2.3.5) activerecord (2.3.5) activerecord-nulldb-adapter (0.2.0) activeresource (2.3.5) activesupport (2.3.5) addressable (2.1.2) appengine-apis (0.0.15) appengine-jruby-jars (0.0.8.pre, 0.0.7) appengine-rack (0.0.8) appengine-sdk (1.3.3.1) appengine-tools (0.0.12) bundler08 (0.8.5) dm-appengine (0.0.8) dm-ar-finders (0.10.2) dm-core (0.10.2) dm-timestamps (0.10.2) dm-validations (0.10.2) extlib (0.9.14) fxri (0.3.7, 0.3.6) google-appengine (0.0.12) hpricot (0.8.2 x86-mswin32, 0.6 mswin32) jruby-rack (0.9.8, 0.9.7) log4r (1.1.7, 1.0.5) rack (1.1.0, 1.0.1) rails (2.3.5) rails_appengine (0.0.3) rails_dm_datastore (0.2.9) rake (0.8.7, 0.7.3) rubygems-update (1.3.7, 1.3.6) rubyzip (0.9.4) sources (0.0.1) win32-api (1.4.6 x86-mswin32-60, 1.0.4 mswin32) win32-clipboard (0.5.2, 0.4.3) win32-dir (0.3.6, 0.3.2) win32-eventlog (0.5.2, 0.4.6) win32-file (0.6.3, 0.5.4) win32-file-stat (1.3.4, 1.2.7) win32-process (0.6.2, 0.5.3) win32-sapi (0.1.5, 0.1.4) win32-sound (0.4.2, 0.4.1) windows-api (0.4.0, 0.2.0) windows-pr (1.0.9, 0.7.2) I'm unable to attach the full logs of the exceptions because of the character limits, but I can provide them under request. Here's an abstract of them: DummyDynamicScope (dev and prod envs): 14-may-2010 7:18:40 com.google.appengine.tools.development.ApiProxyLocalImpl log SEVERE: [1273821520195000] javax.servlet.ServletContext log: Application Error java.lang.RuntimeException: DummyDynamicScope should never be used for backref storage at org.jruby.runtime.scope.DummyDynamicScope.getBackRef(DummyDynamicScope.java:49) at org.jruby.RubyRegexp.updateBackRef(RubyRegexp.java:1404) at org.jruby.RubyRegexp.updateBackRef(RubyRegexp.java:1396) at org.jruby.RubyRegexp.search(RubyRegexp.java:1386) at org.jruby.RubyRegexp.op_match(RubyRegexp.java:1301) at org.jruby.RubyString.op_match(RubyString.java:1446) at org.jruby.RubyString$i_method_1_0$RUBYINVOKER$op_match.call(org/jruby/RubyString$i_method_1_0$RUBYINVOKER$op_match.gen) at org.jruby.internal.runtime.methods.JavaMethod$JavaMethodOneOrN.call(JavaMethod.java:721) at org.jruby.RubyClass.finvoke(RubyClass.java:472) at org.jruby.RubyObject.send(RubyObject.java:1442) at org.jruby.RubyObject$i_method_multi$RUBYINVOKER$send.call(org/jruby/RubyObject$i_method_multi$RUBYINVOKER$send.gen) at org.jruby.internal.runtime.methods.JavaMethod$JavaMethodZeroOrOneOrTwoOrNBlock.call(JavaMethod.java:276) at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:330) at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:189) at ruby.jit.ruby.C_3a_.Desarrollo.AppEngine.gorgory.WEB_minus_INF.lib.gems_dot_jar.bundler_gems.jruby.$1_dot_8.gems.dm_minus_validations_minus_0_dot_10_dot_2.lib.dm_minus_validations.validators.numeric_validator.validate_with_comparison at ruby.jit.ruby.C_3a_.Desarrollo.AppEngine.gorgory.WEB_minus_INF.lib.gems_dot_jar.bundler_gems.jruby.$1_dot_8.gems.dm_minus_validations_minus_0_dot_10_dot_2.lib.dm_minus_validations.validators.numeric_validator.validate_with_comparison at org.jruby.internal.runtime.methods.JittedMethod.call(JittedMethod.java:102) at org.jruby.internal.runtime.methods.DefaultMethod.call(DefaultMethod.java:144) at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:280) at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:69) at org.jruby.ast.FCallManyArgsNode.interpret(FCallManyArgsNode.java:60) at org.jruby.ast.NewlineNode.interpret(NewlineNode.java:104) at org.jruby.internal.runtime.methods.InterpretedMethod.call(InterpretedMethod.java:229) at org.jruby.internal.runtime.methods.DefaultMethod.call(DefaultMethod.java:193) at org.jruby.RubyClass.finvoke(RubyClass.java:491) at org.jruby.RubyObject.send(RubyObject.java:1448) at org.jruby.RubyObject$i_method_multi$RUBYINVOKER$send.call(org/jruby/RubyObject$i_method_multi$RUBYINVOKER$send.gen) at org.jruby.internal.runtime.methods.JavaMethod$JavaMethodZeroOrOneOrTwoOrThreeOrNBlock.call(JavaMethod.java:293) at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:350) at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:229) at ruby.jit.ruby.C_3a_.Desarrollo.AppEngine.gorgory.WEB_minus_INF.lib.gems_dot_jar.bundler_gems.jruby.$1_dot_8.gems.dm_minus_validations_minus_0_dot_10_dot_2.lib.dm_minus_validations.validators.numeric_validator.validate_with28985350_50 at ruby.jit.ruby.C_3a_.Desarrollo.AppEngine.gorgory.WEB_minus_INF.lib.gems_dot_jar.bundler_gems.jruby.$1_dot_8.gems.dm_minus_validations_minus_0_dot_10_dot_2.lib.dm_minus_validations.validators.numeric_validator.validate_with28985350_50 at org.jruby.internal.runtime.methods.JittedMethod.call(JittedMethod.java:221) at org.jruby.internal.runtime.methods.DefaultMethod.call(DefaultMethod.java:201) at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:227) at org.jruby.ast.FCallThreeArgNode.interpret(FCallThreeArgNode.java:40) Reflection (only prod env): Java::JavaLang::SecurityException (java.lang.IllegalAccessException: Reflection is not allowed on public int java.lang.String$CaseInsensitiveComparator.compare(java.lang.String,java.lang.String)): com.google.appengine.runtime.Request.process-92563a0605f433ea(Request.java) java.lang.reflect.AccessibleObject.setAccessible(AccessibleObject.java:40) org.jruby.javasupport.JavaMethod.<init>(JavaMethod.java:176) org.jruby.javasupport.JavaMethod.create(JavaMethod.java:183) org.jruby.java.invokers.MethodInvoker.createCallable(MethodInvoker.java:23) org.jruby.java.invokers.RubyToJavaInvoker.<init>(RubyToJavaInvoker.java:63) org.jruby.java.invokers.MethodInvoker.<init>(MethodInvoker.java:13) org.jruby.java.invokers.InstanceMethodInvoker.<init>(InstanceMethodInvoker.java:15) org.jruby.javasupport.JavaClass$InstanceMethodInvokerInstaller.install(JavaClass.java:339) org.jruby.javasupport.JavaClass.installClassMethods(JavaClass.java:723) org.jruby.javasupport.JavaClass.setupProxy(JavaClass.java:586) org.jruby.javasupport.Java.createProxyClass(Java.java:506) org.jruby.javasupport.Java.getProxyClass(Java.java:445) org.jruby.javasupport.Java.getInstance(Java.java:354) org.jruby.javasupport.JavaUtil.convertJavaToUsableRubyObject(JavaUtil.java:143) org.jruby.javasupport.JavaClass$ConstantField.install(JavaClass.java:360) org.jruby.javasupport.JavaClass.installClassFields(JavaClass.java:711) org.jruby.javasupport.JavaClass.setupProxy(JavaClass.java:585) org.jruby.javasupport.Java.createProxyClass(Java.java:506) org.jruby.javasupport.Java.getProxyClass(Java.java:445) org.jruby.javasupport.Java.getProxyOrPackageUnderPackage(Java.java:885) org.jruby.javasupport.Java.get_proxy_or_package_under_package(Java.java:918) org.jruby.javasupport.JavaUtilities.get_proxy_or_package_under_package(JavaUtilities.java:54) org.jruby.javasupport.JavaUtilities$s_method_2_0$RUBYINVOKER$get_proxy_or_package_under_package.call(org/jruby/javasupport/JavaUtilities$s_method_2_0$RUBYINVOKER$get_proxy_or_package_under_package.gen:65535) org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:329) org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:188) org.jruby.ast.CallTwoArgNode.interpret(CallTwoArgNode.java:59) org.jruby.ast.NewlineNode.interpret(NewlineNode.java:104) org.jruby.ast.BlockNode.interpret(BlockNode.java:71) org.jruby.internal.runtime.methods.InterpretedMethod.call(InterpretedMethod.java:113) org.jruby.internal.runtime.methods.DefaultMethod.call(DefaultMethod.java:138) org.jruby.javasupport.util.RuntimeHelpers$MethodMissingMethod.call(RuntimeHelpers.java:389) org.jruby.internal.runtime.methods.DynamicMethod.call(DynamicMethod.java:182) What should I do now? Any hint would be wellcome. Thanks!

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  • Async ignored on AJAX requests on Nginx server

    - by eComEvo
    Despite sending an async request to the server over AJAX, the server will not respond until the previous unrelated request has finished. The following code is only broken in this way on Nginx, but runs perfectly on Apache. This call will start a background process and it waits for it to complete so it can display the final result. $.ajax({ type: 'GET', async: true, url: $(this).data('route'), data: $('input[name=data]').val(), dataType: 'json', success: function (data) { /* do stuff */} error: function (data) { /* handle errors */} }); The below is called after the above, which on Apache requires 100ms to execute and repeats itself, showing progress for data being written in the background: checkStatusInterval = setInterval(function () { $.ajax({ type: 'GET', async: false, cache: false, url: '/process-status?process=' + currentElement.attr('id'), dataType: 'json', success: function (data) { /* update progress bar and status message */ } }); }, 1000); Unfortunately, when this script is run from nginx, the above progress request never even finishes a single request until the first AJAX request that sent the data is done. If I change the async to TRUE in the above, it executes one every interval, but none of them complete until that very first AJAX request finishes. Here is the main nginx conf file: #user nobody; worker_processes 1; #error_log logs/error.log; #error_log logs/error.log notice; #error_log logs/error.log info; #pid logs/nginx.pid; events { worker_connections 1024; } http { include mime.types; default_type application/octet-stream; server_names_hash_bucket_size 64; # configure temporary paths # nginx is started with param -p, setting nginx path to serverpack installdir fastcgi_temp_path temp/fastcgi; uwsgi_temp_path temp/uwsgi; scgi_temp_path temp/scgi; client_body_temp_path temp/client-body 1 2; proxy_temp_path temp/proxy; log_format main '$remote_addr - $remote_user [$time_local] "$request" ' '$status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; #access_log logs/access.log main; # Sendfile copies data between one FD and other from within the kernel. # More efficient than read() + write(), since the requires transferring data to and from the user space. sendfile on; # Tcp_nopush causes nginx to attempt to send its HTTP response head in one packet, # instead of using partial frames. This is useful for prepending headers before calling sendfile, # or for throughput optimization. tcp_nopush on; # don't buffer data-sends (disable Nagle algorithm). Good for sending frequent small bursts of data in real time. tcp_nodelay on; types_hash_max_size 2048; # Timeout for keep-alive connections. Server will close connections after this time. keepalive_timeout 90; # Number of requests a client can make over the keep-alive connection. This is set high for testing. keepalive_requests 100000; # allow the server to close the connection after a client stops responding. Frees up socket-associated memory. reset_timedout_connection on; # send the client a "request timed out" if the body is not loaded by this time. Default 60. client_header_timeout 20; client_body_timeout 60; # If the client stops reading data, free up the stale client connection after this much time. Default 60. send_timeout 60; # Size Limits client_body_buffer_size 64k; client_header_buffer_size 4k; client_max_body_size 8M; # FastCGI fastcgi_connect_timeout 60; fastcgi_send_timeout 120; fastcgi_read_timeout 300; # default: 60 secs; when step debugging with XDEBUG, you need to increase this value fastcgi_buffer_size 64k; fastcgi_buffers 4 64k; fastcgi_busy_buffers_size 128k; fastcgi_temp_file_write_size 128k; # Caches information about open FDs, freqently accessed files. open_file_cache max=200000 inactive=20s; open_file_cache_valid 30s; open_file_cache_min_uses 2; open_file_cache_errors on; # Turn on gzip output compression to save bandwidth. # http://wiki.nginx.org/HttpGzipModule gzip on; gzip_disable "MSIE [1-6]\.(?!.*SV1)"; gzip_http_version 1.1; gzip_vary on; gzip_proxied any; #gzip_proxied expired no-cache no-store private auth; gzip_comp_level 6; gzip_buffers 16 8k; gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript application/javascript; # show all files and folders autoindex on; server { # access from localhost only listen 127.0.0.1:80; server_name localhost; root www; # the following default "catch-all" configuration, allows access to the server from outside. # please ensure your firewall allows access to tcp/port 80. check your "skype" config. # listen 80; # server_name _; log_not_found off; charset utf-8; access_log logs/access.log main; # handle files in the root path /www location / { index index.php index.html index.htm; } #error_page 404 /404.html; # redirect server error pages to the static page /50x.html # error_page 500 502 503 504 /50x.html; location = /50x.html { root www; } # pass the PHP scripts to FastCGI server listening on 127.0.0.1:9100 # location ~ \.php$ { try_files $uri =404; fastcgi_pass 127.0.0.1:9100; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; include fastcgi_params; } # add expire headers location ~* ^.+.(gif|ico|jpg|jpeg|png|flv|swf|pdf|mp3|mp4|xml|txt|js|css)$ { expires 30d; } # deny access to .htaccess files (if Apache's document root concurs with nginx's one) # deny access to git & svn repositories location ~ /(\.ht|\.git|\.svn) { deny all; } } # include config files of "enabled" domains include domains-enabled/*.conf; } Here is the enabled domain conf file: access_log off; access_log C:/server/www/test.dev/logs/access.log; error_log C:/server/www/test.dev/logs/error.log; # HTTP Server server { listen 127.0.0.1:80; server_name test.dev; root C:/server/www/test.dev/public; index index.php; rewrite_log on; default_type application/octet-stream; #include /etc/nginx/mime.types; # Include common configurations. include domains-common/location.conf; } # HTTPS server server { listen 443 ssl; server_name test.dev; root C:/server/www/test.dev/public; index index.php; rewrite_log on; default_type application/octet-stream; #include /etc/nginx/mime.types; # Include common configurations. include domains-common/location.conf; include domains-common/ssl.conf; } Contents of ssl.conf: # OpenSSL for HTTPS connections. ssl on; ssl_certificate C:/server/bin/openssl/certs/cert.pem; ssl_certificate_key C:/server/bin/openssl/certs/cert.key; ssl_session_timeout 5m; ssl_protocols SSLv3 TLSv1 TLSv1.1 TLSv1.2; ssl_ciphers HIGH:!aNULL:!MD5; ssl_prefer_server_ciphers on; # Pass the PHP scripts to FastCGI server listening on 127.0.0.1:9100 location ~ \.php$ { try_files $uri =404; fastcgi_param HTTPS on; fastcgi_pass 127.0.0.1:9100; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; include fastcgi_params; } Contents of location.conf: # Remove trailing slash to please Laravel routing system. if (!-d $request_filename) { rewrite ^/(.+)/$ /$1 permanent; } location / { try_files $uri $uri/ /index.php?$query_string; } # We don't need .ht files with nginx. location ~ /(\.ht|\.git|\.svn) { deny all; } # Added cache headers for images. location ~* \.(png|jpg|jpeg|gif)$ { expires 30d; log_not_found off; } # Only 3 hours on CSS/JS to allow me to roll out fixes during early weeks. location ~* \.(js|css)$ { expires 3h; log_not_found off; } # Add expire headers. location ~* ^.+.(gif|ico|jpg|jpeg|png|flv|swf|pdf|mp3|mp4|xml|txt)$ { expires 30d; } # Pass the PHP scripts to FastCGI server listening on 127.0.0.1:9100 location ~ \.php$ { try_files $uri /index.php =404; fastcgi_index index.php; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; include fastcgi_params; fastcgi_pass 127.0.0.1:9100; } Any ideas where this is going wrong?

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  • High Load mysql on Debian server stops every day. Why?

    - by Oleg Abrazhaev
    I have Debian server with 32 gb memory. And there is apache2, memcached and nginx on this server. Memory load always on maximum. Only 500m free. Most memory leak do MySql. Apache only 70 clients configured, other services small memory usage. When mysql use all memory it stops. And nothing works, need mysql reboot. Mysql configured use maximum 24 gb memory. I have hight weight InnoDB bases. (400000 rows, 30 gb). And on server multithread daemon, that makes many inserts in this tables, thats why InnoDB. There is my mysql config. [mysqld] # # * Basic Settings # default-time-zone = "+04:00" user = mysql pid-file = /var/run/mysqld/mysqld.pid socket = /var/run/mysqld/mysqld.sock port = 3306 basedir = /usr datadir = /var/lib/mysql tmpdir = /tmp language = /usr/share/mysql/english skip-external-locking default-time-zone='Europe/Moscow' # # Instead of skip-networking the default is now to listen only on # localhost which is more compatible and is not less secure. # # * Fine Tuning # #low_priority_updates = 1 concurrent_insert = ALWAYS wait_timeout = 600 interactive_timeout = 600 #normal key_buffer_size = 2024M #key_buffer_size = 1512M #70% hot cache key_cache_division_limit= 70 #16-32 max_allowed_packet = 32M #1-16M thread_stack = 8M #40-50 thread_cache_size = 50 #orderby groupby sort sort_buffer_size = 64M #same myisam_sort_buffer_size = 400M #temp table creates when group_by tmp_table_size = 3000M #tables in memory max_heap_table_size = 3000M #on disk open_files_limit = 10000 table_cache = 10000 join_buffer_size = 5M # This replaces the startup script and checks MyISAM tables if needed # the first time they are touched myisam-recover = BACKUP #myisam_use_mmap = 1 max_connections = 200 thread_concurrency = 8 # # * Query Cache Configuration # #more ignored query_cache_limit = 50M query_cache_size = 210M #on query cache query_cache_type = 1 # # * Logging and Replication # # Both location gets rotated by the cronjob. # Be aware that this log type is a performance killer. #log = /var/log/mysql/mysql.log # # Error logging goes to syslog. This is a Debian improvement :) # # Here you can see queries with especially long duration log_slow_queries = /var/log/mysql/mysql-slow.log long_query_time = 1 log-queries-not-using-indexes # # The following can be used as easy to replay backup logs or for replication. # note: if you are setting up a replication slave, see README.Debian about # other settings you may need to change. #server-id = 1 #log_bin = /var/log/mysql/mysql-bin.log server-id = 1 log-bin = /var/lib/mysql/mysql-bin #replicate-do-db = gate log-bin-index = /var/lib/mysql/mysql-bin.index log-error = /var/lib/mysql/mysql-bin.err relay-log = /var/lib/mysql/relay-bin relay-log-info-file = /var/lib/mysql/relay-bin.info relay-log-index = /var/lib/mysql/relay-bin.index binlog_do_db = 24avia expire_logs_days = 10 max_binlog_size = 100M read_buffer_size = 4024288 innodb_buffer_pool_size = 5000M innodb_flush_log_at_trx_commit = 2 innodb_thread_concurrency = 8 table_definition_cache = 2000 group_concat_max_len = 16M #binlog_do_db = gate #binlog_ignore_db = include_database_name # # * BerkeleyDB # # Using BerkeleyDB is now discouraged as its support will cease in 5.1.12. #skip-bdb # # * InnoDB # # InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/. # Read the manual for more InnoDB related options. There are many! # You might want to disable InnoDB to shrink the mysqld process by circa 100MB. #skip-innodb # # * Security Features # # Read the manual, too, if you want chroot! # chroot = /var/lib/mysql/ # # For generating SSL certificates I recommend the OpenSSL GUI "tinyca". # # ssl-ca=/etc/mysql/cacert.pem # ssl-cert=/etc/mysql/server-cert.pem # ssl-key=/etc/mysql/server-key.pem [mysqldump] quick quote-names max_allowed_packet = 500M [mysql] #no-auto-rehash # faster start of mysql but no tab completition [isamchk] key_buffer = 32M key_buffer_size = 512M # # * NDB Cluster # # See /usr/share/doc/mysql-server-*/README.Debian for more information. # # The following configuration is read by the NDB Data Nodes (ndbd processes) # not from the NDB Management Nodes (ndb_mgmd processes). # # [MYSQL_CLUSTER] # ndb-connectstring=127.0.0.1 # # * IMPORTANT: Additional settings that can override those from this file! # The files must end with '.cnf', otherwise they'll be ignored. # !includedir /etc/mysql/conf.d/ Please, help me make it stable. Memory used /etc/mysql # free total used free shared buffers cached Mem: 32930800 32766424 164376 0 139208 23829196 -/+ buffers/cache: 8798020 24132780 Swap: 33553328 44660 33508668 Maybe my problem not in memory, but MySQL stops every day. As you can see, cache memory free 24 gb. Thank to Michael Hampton? for correction. Load overage on server 3.5. Maybe hdd or another problem? Maybe my config not optimal for 30gb InnoDB ? I'm already try mysqltuner and tunung-primer.sh , but they marked all green. Mysqltuner output mysqltuner >> MySQLTuner 1.0.1 - Major Hayden <[email protected]> >> Bug reports, feature requests, and downloads at http://mysqltuner.com/ >> Run with '--help' for additional options and output filtering -------- General Statistics -------------------------------------------------- [--] Skipped version check for MySQLTuner script [OK] Currently running supported MySQL version 5.5.24-9-log [OK] Operating on 64-bit architecture -------- Storage Engine Statistics ------------------------------------------- [--] Status: -Archive -BDB -Federated +InnoDB -ISAM -NDBCluster [--] Data in MyISAM tables: 112G (Tables: 1528) [--] Data in InnoDB tables: 39G (Tables: 340) [--] Data in PERFORMANCE_SCHEMA tables: 0B (Tables: 17) [!!] Total fragmented tables: 344 -------- Performance Metrics ------------------------------------------------- [--] Up for: 8h 18m 33s (14M q [478.333 qps], 259K conn, TX: 9B, RX: 5B) [--] Reads / Writes: 84% / 16% [--] Total buffers: 10.5G global + 81.1M per thread (200 max threads) [OK] Maximum possible memory usage: 26.3G (83% of installed RAM) [OK] Slow queries: 1% (259K/14M) [!!] Highest connection usage: 100% (201/200) [OK] Key buffer size / total MyISAM indexes: 1.5G/5.6G [OK] Key buffer hit rate: 100.0% (6B cached / 1M reads) [OK] Query cache efficiency: 74.3% (8M cached / 11M selects) [OK] Query cache prunes per day: 0 [OK] Sorts requiring temporary tables: 0% (0 temp sorts / 247K sorts) [!!] Joins performed without indexes: 106025 [!!] Temporary tables created on disk: 49% (351K on disk / 715K total) [OK] Thread cache hit rate: 99% (249 created / 259K connections) [!!] Table cache hit rate: 15% (2K open / 13K opened) [OK] Open file limit used: 15% (3K/20K) [OK] Table locks acquired immediately: 99% (4M immediate / 4M locks) [!!] InnoDB data size / buffer pool: 39.4G/5.9G -------- Recommendations ----------------------------------------------------- General recommendations: Run OPTIMIZE TABLE to defragment tables for better performance MySQL started within last 24 hours - recommendations may be inaccurate Reduce or eliminate persistent connections to reduce connection usage Adjust your join queries to always utilize indexes Temporary table size is already large - reduce result set size Reduce your SELECT DISTINCT queries without LIMIT clauses Increase table_cache gradually to avoid file descriptor limits Variables to adjust: max_connections (> 200) wait_timeout (< 600) interactive_timeout (< 600) join_buffer_size (> 5.0M, or always use indexes with joins) table_cache (> 10000) innodb_buffer_pool_size (>= 39G) Mysql primer output -- MYSQL PERFORMANCE TUNING PRIMER -- - By: Matthew Montgomery - MySQL Version 5.5.24-9-log x86_64 Uptime = 0 days 8 hrs 20 min 50 sec Avg. qps = 478 Total Questions = 14369568 Threads Connected = 16 Warning: Server has not been running for at least 48hrs. It may not be safe to use these recommendations To find out more information on how each of these runtime variables effects performance visit: http://dev.mysql.com/doc/refman/5.5/en/server-system-variables.html Visit http://www.mysql.com/products/enterprise/advisors.html for info about MySQL's Enterprise Monitoring and Advisory Service SLOW QUERIES The slow query log is enabled. Current long_query_time = 1.000000 sec. You have 260626 out of 14369701 that take longer than 1.000000 sec. to complete Your long_query_time seems to be fine BINARY UPDATE LOG The binary update log is enabled Binlog sync is not enabled, you could loose binlog records during a server crash WORKER THREADS Current thread_cache_size = 50 Current threads_cached = 45 Current threads_per_sec = 0 Historic threads_per_sec = 0 Your thread_cache_size is fine MAX CONNECTIONS Current max_connections = 200 Current threads_connected = 11 Historic max_used_connections = 201 The number of used connections is 100% of the configured maximum. You should raise max_connections INNODB STATUS Current InnoDB index space = 214 M Current InnoDB data space = 39.40 G Current InnoDB buffer pool free = 0 % Current innodb_buffer_pool_size = 5.85 G Depending on how much space your innodb indexes take up it may be safe to increase this value to up to 2 / 3 of total system memory MEMORY USAGE Max Memory Ever Allocated : 23.46 G Configured Max Per-thread Buffers : 15.84 G Configured Max Global Buffers : 7.54 G Configured Max Memory Limit : 23.39 G Physical Memory : 31.40 G Max memory limit seem to be within acceptable norms KEY BUFFER Current MyISAM index space = 5.61 G Current key_buffer_size = 1.47 G Key cache miss rate is 1 : 5578 Key buffer free ratio = 77 % Your key_buffer_size seems to be fine QUERY CACHE Query cache is enabled Current query_cache_size = 200 M Current query_cache_used = 101 M Current query_cache_limit = 50 M Current Query cache Memory fill ratio = 50.59 % Current query_cache_min_res_unit = 4 K MySQL won't cache query results that are larger than query_cache_limit in size SORT OPERATIONS Current sort_buffer_size = 64 M Current read_rnd_buffer_size = 256 K Sort buffer seems to be fine JOINS Current join_buffer_size = 5.00 M You have had 106606 queries where a join could not use an index properly You have had 8 joins without keys that check for key usage after each row join_buffer_size >= 4 M This is not advised You should enable "log-queries-not-using-indexes" Then look for non indexed joins in the slow query log. OPEN FILES LIMIT Current open_files_limit = 20210 files The open_files_limit should typically be set to at least 2x-3x that of table_cache if you have heavy MyISAM usage. Your open_files_limit value seems to be fine TABLE CACHE Current table_open_cache = 10000 tables Current table_definition_cache = 2000 tables You have a total of 1910 tables You have 2151 open tables. The table_cache value seems to be fine TEMP TABLES Current max_heap_table_size = 2.92 G Current tmp_table_size = 2.92 G Of 366426 temp tables, 49% were created on disk Perhaps you should increase your tmp_table_size and/or max_heap_table_size to reduce the number of disk-based temporary tables Note! BLOB and TEXT columns are not allow in memory tables. If you are using these columns raising these values might not impact your ratio of on disk temp tables. TABLE SCANS Current read_buffer_size = 3 M Current table scan ratio = 2846 : 1 read_buffer_size seems to be fine TABLE LOCKING Current Lock Wait ratio = 1 : 185 You may benefit from selective use of InnoDB. If you have long running SELECT's against MyISAM tables and perform frequent updates consider setting 'low_priority_updates=1'

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  • Char error C langauge

    - by Nadeem tabbaa
    i have a project for a course, i did almost everything but i have this error i dont know who to solve it... the project about doing our own shell some of them we have to write our code, others we will use the fork method.. this is the code, #include <sys/wait.h> #include <dirent.h> #include <limits.h> #include <errno.h> #include <stdlib.h> #include <string.h> #include<stdio.h> #include<fcntl.h> #include<unistd.h> #include<sys/stat.h> #include<sys/types.h> int main(int argc, char **argv) { pid_t pid; char str[21], *arg[10]; int x,status,number; system("clear"); while(1) { printf("Rshell>" ); fgets(str,21,stdin); x = 0; arg[x] = strtok(str, " \n\t"); while(arg[x]) arg[++x] = strtok(NULL, " \n\t"); if(NULL!=arg[0]) { if(strcasecmp(arg[0],"cat")==0) //done { int f=0,n; char l[1]; struct stat s; if(x!=2) { printf("Mismatch argument\n"); } /*if(access(arg[1],F_OK)) { printf("File Exist"); exit(1); } if(stat(arg[1],&s)<0) { printf("Stat ERROR"); exit(1); } if(S_ISREG(s.st_mode)<0) { printf("Not a Regular FILE"); exit(1); } if(geteuid()==s.st_uid) if(s.st_mode & S_IRUSR) f=1; else if(getegid()==s.st_gid) if(s.st_mode & S_IRGRP) f=1; else if(s.st_mode & S_IROTH) f=1; if(!f) { printf("Permission denied"); exit(1); }*/ f=open(arg[1],O_RDONLY); while((n=read(f,l,1))>0) write(1,l,n); } else if(strcasecmp(arg[0],"rm")==0) //done { if( unlink( arg[1] ) != 0 ) perror( "Error deleting file" ); else puts( "File successfully deleted" ); } else if(strcasecmp(arg[0],"rmdir")==0) //done { if( remove( arg[1] ) != 0 ) perror( "Error deleting Directory" ); else puts( "Directory successfully deleted" ); } else if(strcasecmp(arg[0],"ls")==0) //done { DIR *dir; struct dirent *dirent; char *where = NULL; //printf("x== %i\n",x); //printf("x== %s\n",arg[1]); //printf("x== %i\n",get_current_dir_name()); if (x == 1) where = get_current_dir_name(); else where = arg[1]; if (NULL == (dir = opendir(where))) { fprintf(stderr,"%d (%s) opendir %s failed\n", errno, strerror(errno), where); return 2; } while (NULL != (dirent = readdir(dir))) { printf("%s\n", dirent->d_name); } closedir(dir); } else if(strcasecmp(arg[0],"cp")==0) //not yet for Raed { FILE *from, *to; char ch; if(argc!=3) { printf("Usage: copy <source> <destination>\n"); exit(1); } /* open source file */ if((from = fopen(argv[1], "rb"))==NULL) { printf("Cannot open source file.\n"); exit(1); } /* open destination file */ if((to = fopen(argv[2], "wb"))==NULL) { printf("Cannot open destination file.\n"); exit(1); } /* copy the file */ while(!feof(from)) { ch = fgetc(from); if(ferror(from)) { printf("Error reading source file.\n"); exit(1); } if(!feof(from)) fputc(ch, to); if(ferror(to)) { printf("Error writing destination file.\n"); exit(1); } } if(fclose(from)==EOF) { printf("Error closing source file.\n"); exit(1); } if(fclose(to)==EOF) { printf("Error closing destination file.\n"); exit(1); } } else if(strcasecmp(arg[0],"mv")==0)//done { if( rename(arg[1],arg[2]) != 0 ) perror( "Error moving file" ); else puts( "File successfully moved" ); } else if(strcasecmp(arg[0],"hi")==0)//done { printf("hello\n"); } else if(strcasecmp(arg[0],"exit")==0) // done { return 0; } else if(strcasecmp(arg[0],"sleep")==0) // done { if(x==1) printf("plz enter the # seconds to sleep\n"); else sleep(atoi(arg[1])); } else if(strcmp(arg[0],"history")==0) // not done { FILE *infile; //char fname[40]; char line[100]; int lcount; ///* Read in the filename */ //printf("Enter the name of a ascii file: "); //fgets(History.txt, sizeof(fname), stdin); /* Open the file. If NULL is returned there was an error */ if((infile = fopen("History.txt", "r")) == NULL) { printf("Error Opening File.\n"); exit(1); } while( fgets(line, sizeof(line), infile) != NULL ) { /* Get each line from the infile */ lcount++; /* print the line number and data */ printf("Line %d: %s", lcount, line); } fclose(infile); /* Close the file */ writeHistory(arg); //write to txt file every new executed command //read from the file once the history command been called //if a command called not for the first time then just replace it to the end of the file } else if(strncmp(arg[0],"@",1)==0) // not done { //scripting files // read from the file command by command and executing them } else if(strcmp(arg[0],"type")==0) //not done { //if(x==1) //printf("plz enter the argument\n"); //else //type((arg[1])); } else { pid = fork( ); if (pid == 0) { execlp(arg[0], arg[0], arg[1], arg[2], NULL); printf ("EXEC Failed\n"); } else { wait(&status); if(strcmp(arg[0],"clear")!=0) { printf("status %04X\n",status); if(WIFEXITED(status)) printf("Normal termination, exit code %d\n", WEXITSTATUS(status)); else printf("Abnormal termination\n"); } } } } } } void writeHistory(char *arg[]) { FILE *file; file = fopen("History.txt","a+"); /* apend file (add text to a file or create a file if it does not exist.*/ int i =0; while(strcasecmp(arg[0],NULL)==0) { fprintf(file,"%s ",arg[i]); /*writes*/ } fprintf(file,"\n"); /*new line*/ fclose(file); /*done!*/ getchar(); /* pause and wait for key */ //return 0; } the thing is when i compile the code, this what it gives me /home/ugics/st255375/ICS431Labs/Project/Rshell.c: At top level: /home/ugics/st255375/ICS431Labs/Project/Rshell.c:264: warning: conflicting types for ‘writeHistory’ /home/ugics/st255375/ICS431Labs/Project/Rshell.c:217: note: previous implicit declaration of ‘writeHistory’ was here can any one help me??? thanks

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  • C++ scoping error

    - by Pat Murray
    I have the following code: #include "Student.h" #include "SortedList.h" using namespace std; int main() { // points to the sorted list object SortedList *list = new SortedList; //This is line 17 // array to hold 100 student objects Student create[100]; int num = 100000; // holds different ID numbers // fills an array with 100 students of various ID numbers for (Student &x : create) { x = new Student(num); num += 100; } // insert all students into the sorted list for (Student &x : create) list->insert(&x); delete list; return 0; } And I keep getting the compile time error: main.cpp: In function ‘int main()’: main.cpp:17: error: ‘SortedList’ was not declared in this scope main.cpp:17: error: ‘list’ was not declared in this scope main.cpp:17: error: expected type-specifier before ‘SortedList’ main.cpp:17: error: expected `;' before ‘SortedList’ main.cpp:20: error: ‘Student’ was not declared in this scope main.cpp:20: error: expected primary-expression before ‘]’ token main.cpp:20: error: expected `;' before ‘create’ main.cpp:25: error: expected `;' before ‘x’ main.cpp:31: error: expected primary-expression before ‘for’ main.cpp:31: error: expected `;' before ‘for’ main.cpp:31: error: expected primary-expression before ‘for’ main.cpp:31: error: expected `)' before ‘for’ main.cpp:31: error: expected `;' before ‘x’ main.cpp:34: error: type ‘<type error>’ argument given to ‘delete’, expected pointer main.cpp:35: error: expected primary-expression before ‘return’ main.cpp:35: error: expected `)' before ‘return’ My Student.cpp and SortedList.cpp files compile just fine. They both also include .h files. I just do not understand why I get an error on that line. It seems to be a small issue though. Any insight would be appreciated. UPDATE1: I originally had .h files included, but i changed it when trying to figure out the cause of the error. The error remains with the .h files included though. UPDATE2: SortedList.h #ifndef SORTEDLIST_H #define SORTEDLIST_H #include "Student.h" /* * SortedList class * * A SortedList is an ordered collection of Students. The Students are ordered * from lowest numbered student ID to highest numbered student ID. */ class SortedList { public: SortedList(); // Constructs an empty list. SortedList(const SortedList & l); // Constructs a copy of the given student object ~SortedList(); // Destructs the sorted list object const SortedList & operator=(const SortedList & l); // Defines the assignment operator between two sorted list objects bool insert(Student *s); // If a student with the same ID is not already in the list, inserts // the given student into the list in the appropriate place and returns // true. If there is already a student in the list with the same ID // then the list is not changed and false is returned. Student *find(int studentID); // Searches the list for a student with the given student ID. If the // student is found, it is returned; if it is not found, NULL is returned. Student *remove(int studentID); // Searches the list for a student with the given student ID. If the // student is found, the student is removed from the list and returned; // if no student is found with the given ID, NULL is returned. // Note that the Student is NOT deleted - it is returned - however, // the removed list node should be deleted. void print() const; // Prints out the list of students to standard output. The students are // printed in order of student ID (from smallest to largest), one per line private: // Since Listnodes will only be used within the SortedList class, // we make it private. struct Listnode { Student *student; Listnode *next; }; Listnode *head; // pointer to first node in the list static void freeList(Listnode *L); // Traverses throught the linked list and deallocates each node static Listnode *copyList(Listnode *L); // Returns a pointer to the first node within a particular list }; #endif #ifndef STUDENT_H #define STUDENT_H Student.h #ifndef STUDENT_H #define STUDENT_H /* * Student class * * A Student object contains a student ID, the number of credits, and an * overall GPA. */ class Student { public: Student(); // Constructs a default student with an ID of 0, 0 credits, and 0.0 GPA. Student(int ID); // Constructs a student with the given ID, 0 credits, and 0.0 GPA. Student(int ID, int cr, double grPtAv); // Constructs a student with the given ID, number of credits, and GPA.\ Student(const Student & s); // Constructs a copy of another student object ~Student(); // Destructs a student object const Student & operator=(const Student & rhs); // Defines the assignment operator between two student objects // Accessors int getID() const; // returns the student ID int getCredits() const; // returns the number of credits double getGPA() const; // returns the GPA // Other methods void update(char grade, int cr); // Updates the total credits and overall GPA to take into account the // additions of the given letter grade in a course with the given number // of credits. The update is done by first converting the letter grade // into a numeric value (A = 4.0, B = 3.0, etc.). The new GPA is // calculated using the formula: // // (oldGPA * old_total_credits) + (numeric_grade * cr) // newGPA = --------------------------------------------------- // old_total_credits + cr // // Finally, the total credits is updated (to old_total_credits + cr) void print() const; // Prints out the student to standard output in the format: // ID,credits,GPA // Note: the end-of-line is NOT printed after the student information private: int studentID; int credits; double GPA; }; #endif

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  • Authoritative sources about Database vs. Flatfile decision

    - by FastAl
    <tldr>looking for a reference to a book or other undeniably authoritative source that gives reasons when you should choose a database vs. when you should choose other storage methods. I have provided an un-authoritative list of reasons about 2/3 of the way down this post.</tldr> I have a situation at my company where a database is being used where it would be better to use another solution (in this case, an auto-generated piece of source code that contains a static lookup table, searched by binary sort). Normally, a database would be an OK solution even though the problem does not require a database, e.g, none of the elements of ACID are needed, as it is read-only data, updated about every 3-5 years (also requiring other sourcecode changes), and fits in memory, and can be keyed into via binary search (a tad faster than db, but speed is not an issue). The problem is that this code runs on our enterprise server, but is shared with several PC platforms (some disconnected, some use a central DB, etc.), and parts of it are managed by multiple programming units, parts by the DBAs, parts even by mathematicians in another department, etc. These hit their own platform’s version of their databases (containing their own copy of the static data). What happens is that every implementation, every little change, something different goes wrong. There are many other issues as well. I can’t even use a flatfile, because one mode of running on our enterprise server does not have permission to read files (only databases, and of course, its own literal storage, e.g., in-source table). Of course, other parts of the system use databases in proper, less obscure manners; there is no problem with those parts. So why don’t we just change it? I don’t have administrative ability to force a change. But I’m affected because sometimes I have to help fix the problems, but mostly because it causes outages and tons of extra IT time by other programmers and d*mmit that makes me mad! The reason neither management, nor the designers of the system, can see the problem is that they propose a solution that won’t work: increase communication; implement more safeguards and standards; etc. But every time, in a different part of the already-pared-down but still multi-step processes, a few different diligent, hard-working, top performing IT personnel make a unique subtle error that causes it to fail, sometimes after the last round of testing! And in general these are not single-person failures, but understandable miscommunications. And communication at our company is actually better than most. People just don't think that's the case because they haven't dug into the matter. However, I have it on very good word from somebody with extensive formal study of sociology and psychology that the relatively small amount of less-than-proper database usage in this gigantic cross-platform multi-source, multi-language project is bureaucratically un-maintainable. Impossible. No chance. At least with Human Beings in the loop, and it can’t be automated. In addition, the management and developers who could change this, though intelligent and capable, don’t understand the rigidity of this ‘how humans are’ issue, and are not convincible on the matter. The reason putting the static data in sourcecode will solve the problem is, although the solution is less sexy than a database, it would function with no technical drawbacks; and since the sharing of sourcecode already works very well, you basically erase any database-related effort from this section of the project, along with all the drawbacks of it that are causing problems. OK, that’s the background, for the curious. I won’t be able to convince management that this is an unfixable sociological problem, and that the real solution is coding around these limits of human nature, just as you would code around a bug in a 3rd party component that you can’t change. So what I have to do is exploit the unsuitableness of the database solution, and not do it using logic, but rather authority. I am aware of many reasons, and posts on this site giving reasons for one over the other; I’m not looking for lists of reasons like these (although you can add a comment if I've miss a doozy): WHY USE A DATABASE? instead of flatfile/other DB vs. file: if you need... Random Read / Transparent search optimization Advanced / varied / customizable Searching and sorting capabilities Transaction/rollback Locks, semaphores Concurrency control / Shared users Security 1-many/m-m is easier Easy modification Scalability Load Balancing Random updates / inserts / deletes Advanced query Administrative control of design, etc. SQL / learning curve Debugging / Logging Centralized / Live Backup capabilities Cached queries / dvlp & cache execution plans Interleaved update/read Referential integrity, avoid redundant/missing/corrupt/out-of-sync data Reporting (from on olap or oltp db) / turnkey generation tools [Disadvantages:] Important to get right the first time - professional design - but only b/c it's meant to last s/w & h/w cost Usu. over a network, speed issue (best vs. best design vs. local=even then a separate process req's marshalling/netwk layers/inter-p comm) indicies and query processing can stand in the way of simple processing (vs. flatfile) WHY USE FLATFILE: If you only need... Sequential Row processing only Limited usage append only (no reading, no master key/update) Only Update the record you're reading (fixed length recs only) Too big to fit into memory If Local disk / read-ahead network connection Portability / small system Email / cut & Paste / store as document by novice - simple format Low design learning curve but high cost later WHY USE IN-MEMORY/TABLE (tables, arrays, etc.): if you need... Processing a single db/ff record that was imported Known size of data Static data if hardcoding the table Narrow, unchanging use (e.g., one program or proc) -includes a class that will be shared, but encapsulates its data manipulation Extreme speed needed / high transaction frequency Random access - but search is dependent on implementation Following are some other posts about the topic: http://stackoverflow.com/questions/1499239/database-vs-flat-text-file-what-are-some-technical-reasons-for-choosing-one-over http://stackoverflow.com/questions/332825/are-flat-file-databases-any-good http://stackoverflow.com/questions/2356851/database-vs-flat-files http://stackoverflow.com/questions/514455/databases-vs-plain-text/514530 What I’d like to know is if anybody could recommend a hard, authoritative source containing these reasons. I’m looking for a paper book I can buy, or a reputable website with whitepapers about the issue (e.g., Microsoft, IBM), not counting the user-generated content on those sites. This will have a greater change to elicit a change that I’m looking for: less wasted programmer time, and more reliable programs. Thanks very much for your help. You win a prize for reading such a large post!

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  • How do I prove I should put a table of values in source code instead of a database table?

    - by FastAl
    <tldr>looking for a reference to a book or other undeniably authoritative source that gives reasons when you should choose a database vs. when you should choose other storage methods. I have provided an un-authoritative list of reasons about 2/3 of the way down this post.</tldr> I have a situation at my company where a database is being used where it would be better to use another solution (in this case, an auto-generated piece of source code that contains a static lookup table, searched by binary sort). Normally, a database would be an OK solution even though the problem does not require a database, e.g, none of the elements of ACID are needed, as it is read-only data, updated about every 3-5 years (also requiring other sourcecode changes), and fits in memory, and can be keyed into via binary search (a tad faster than db, but speed is not an issue). The problem is that this code runs on our enterprise server, but is shared with several PC platforms (some disconnected, some use a central DB, etc.), and parts of it are managed by multiple programming units, parts by the DBAs, parts even by mathematicians in another department, etc. These hit their own platform’s version of their databases (containing their own copy of the static data). What happens is that every implementation, every little change, something different goes wrong. There are many other issues as well. I can’t even use a flatfile, because one mode of running on our enterprise server does not have permission to read files (only databases, and of course, its own literal storage, e.g., in-source table). Of course, other parts of the system use databases in proper, less obscure manners; there is no problem with those parts. So why don’t we just change it? I don’t have administrative ability to force a change. But I’m affected because sometimes I have to help fix the problems, but mostly because it causes outages and tons of extra IT time by other programmers and d*mmit that makes me mad! The reason neither management, nor the designers of the system, can see the problem is that they propose a solution that won’t work: increase communication; implement more safeguards and standards; etc. But every time, in a different part of the already-pared-down but still multi-step processes, a few different diligent, hard-working, top performing IT personnel make a unique subtle error that causes it to fail, sometimes after the last round of testing! And in general these are not single-person failures, but understandable miscommunications. And communication at our company is actually better than most. People just don't think that's the case because they haven't dug into the matter. However, I have it on very good word from somebody with extensive formal study of sociology and psychology that the relatively small amount of less-than-proper database usage in this gigantic cross-platform multi-source, multi-language project is bureaucratically un-maintainable. Impossible. No chance. At least with Human Beings in the loop, and it can’t be automated. In addition, the management and developers who could change this, though intelligent and capable, don’t understand the rigidity of this ‘how humans are’ issue, and are not convincible on the matter. The reason putting the static data in sourcecode will solve the problem is, although the solution is less sexy than a database, it would function with no technical drawbacks; and since the sharing of sourcecode already works very well, you basically erase any database-related effort from this section of the project, along with all the drawbacks of it that are causing problems. OK, that’s the background, for the curious. I won’t be able to convince management that this is an unfixable sociological problem, and that the real solution is coding around these limits of human nature, just as you would code around a bug in a 3rd party component that you can’t change. So what I have to do is exploit the unsuitableness of the database solution, and not do it using logic, but rather authority. I am aware of many reasons, and posts on this site giving reasons for one over the other; I’m not looking for lists of reasons like these (although you can add a comment if I've miss a doozy): WHY USE A DATABASE? instead of flatfile/other DB vs. file: if you need... Random Read / Transparent search optimization Advanced / varied / customizable Searching and sorting capabilities Transaction/rollback Locks, semaphores Concurrency control / Shared users Security 1-many/m-m is easier Easy modification Scalability Load Balancing Random updates / inserts / deletes Advanced query Administrative control of design, etc. SQL / learning curve Debugging / Logging Centralized / Live Backup capabilities Cached queries / dvlp & cache execution plans Interleaved update/read Referential integrity, avoid redundant/missing/corrupt/out-of-sync data Reporting (from on olap or oltp db) / turnkey generation tools [Disadvantages:] Important to get right the first time - professional design - but only b/c it's meant to last s/w & h/w cost Usu. over a network, speed issue (best vs. best design vs. local=even then a separate process req's marshalling/netwk layers/inter-p comm) indicies and query processing can stand in the way of simple processing (vs. flatfile) WHY USE FLATFILE: If you only need... Sequential Row processing only Limited usage append only (no reading, no master key/update) Only Update the record you're reading (fixed length recs only) Too big to fit into memory If Local disk / read-ahead network connection Portability / small system Email / cut & Paste / store as document by novice - simple format Low design learning curve but high cost later WHY USE IN-MEMORY/TABLE (tables, arrays, etc.): if you need... Processing a single db/ff record that was imported Known size of data Static data if hardcoding the table Narrow, unchanging use (e.g., one program or proc) -includes a class that will be shared, but encapsulates its data manipulation Extreme speed needed / high transaction frequency Random access - but search is dependent on implementation Following are some other posts about the topic: http://stackoverflow.com/questions/1499239/database-vs-flat-text-file-what-are-some-technical-reasons-for-choosing-one-over http://stackoverflow.com/questions/332825/are-flat-file-databases-any-good http://stackoverflow.com/questions/2356851/database-vs-flat-files http://stackoverflow.com/questions/514455/databases-vs-plain-text/514530 What I’d like to know is if anybody could recommend a hard, authoritative source containing these reasons. I’m looking for a paper book I can buy, or a reputable website with whitepapers about the issue (e.g., Microsoft, IBM), not counting the user-generated content on those sites. This will have a greater change to elicit a change that I’m looking for: less wasted programmer time, and more reliable programs. Thanks very much for your help. You win a prize for reading such a large post!

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  • Ajax, Callback, postback and Sys.WebForms.PageRequestManager.getInstance().add_beginRequest

    - by user338262
    Hi, I have a user control which encapsulates a NumericUpDownExtender. This UserControl implements the interface ICallbackEventHandler, because I want that when a user changes the value of the textbox associated a custom event to be raised in the server. By the other hand each time an async postback is done I shoe a message of loading and disable the whole screen. This works perfect when something is changed in for example an UpdatePanel through this lines of code: Sys.WebForms.PageRequestManager.getInstance().add_beginRequest( function (sender, args) { var modalPopupBehavior = $find('programmaticSavingLoadingModalPopupBehavior'); modalPopupBehavior.show(); } ); The UserControl is placed inside a detailsview which is inside an UpdatePanel in an aspx. When the custom event is raised I want another textbox in the aspx to change its value. So far, When I click on the UpDownExtender, it goes correctly to the server and raises the custom event, and the new value of the textbox is assigned in the server. but it is not changed in the browser. I suspect that the problem is the callback, since I have the same architecture for a UserControl with an AutoCompleteExtender which implement IPostbackEventHandler and it works. Any clues how can I solve this here to make the UpDownNumericExtender user control to work like the AutComplete one? This is the code of the user control and the parent: using System; using System.Web.UI; using System.ComponentModel; using System.Text; namespace Corp.UserControls { [Themeable(true)] public partial class CustomNumericUpDown : CorpNumericUpDown, ICallbackEventHandler { protected void Page_PreRender(object sender, EventArgs e) { if (!Page.IsPostBack) { currentInstanceNumber = CorpAjaxControlToolkitUserControl.getNextInstanceNumber(); } registerControl(this.HFNumericUpDown.ClientID, currentInstanceNumber); string strCallServer = "NumericUpDownCallServer" + currentInstanceNumber.ToString(); // If this function is not written the callback to get the disponibilidadCliente doesn't work if (!Page.ClientScript.IsClientScriptBlockRegistered("ReceiveServerDataNumericUpDown")) { StringBuilder str = new StringBuilder(); str.Append("function ReceiveServerDataNumericUpDown(arg, context) {}").AppendLine(); Page.ClientScript.RegisterClientScriptBlock(typeof(CorpNumericUpDown), "ReceiveServerDataNumericUpDown", str.ToString(), true); } nudeNumericUpDownExtender.BehaviorID = "NumericUpDownEx" + currentInstanceNumber.ToString(); ClientScriptManager cm = Page.ClientScript; String cbReference = cm.GetCallbackEventReference(this, "arg", "ReceiveServerDataNumericUpDown", ""); String callbackScript = "function " + strCallServer + "(arg, context)" + Environment.NewLine + "{" + Environment.NewLine + cbReference + ";" + Environment.NewLine + "}" + Environment.NewLine; cm.RegisterClientScriptBlock(typeof(CustomNumericUpDown), strCallServer, callbackScript, true); base.Page_PreRender(sender,e); } [System.ComponentModel.Browsable(true)] [System.ComponentModel.Bindable(true)] public Int64 Value { get { return (string.IsNullOrEmpty(HFNumericUpDown.Value) ? Int64.Parse("1") : Int64.Parse(HFNumericUpDown.Value)); } set { HFNumericUpDown.Value = value.ToString(); //txtAutoCompleteCliente_AutoCompleteExtender.ContextKey = value.ToString(); // TODO: Change the text of the textbox } } [System.ComponentModel.Browsable(true)] [System.ComponentModel.Bindable(true)] [Description("The text of the numeric up down")] public string Text { get { return txtNumericUpDown.Text; } set { txtNumericUpDown.Text = value; } } public delegate void NumericUpDownChangedHandler(object sender, NumericUpDownChangedArgs e); public event NumericUpDownChangedHandler numericUpDownEvent; [System.ComponentModel.Browsable(true)] [System.ComponentModel.Bindable(true)] [System.ComponentModel.Description("Raised after the number has been increased or decreased")] protected virtual void OnNumericUpDownEvent(object sender, NumericUpDownChangedArgs e) { if (numericUpDownEvent != null) //check to see if anyone has attached to the event numericUpDownEvent(this, e); } #region ICallbackEventHandler Members public string GetCallbackResult() { return "";//throw new NotImplementedException(); } public void RaiseCallbackEvent(string eventArgument) { NumericUpDownChangedArgs nudca = new NumericUpDownChangedArgs(long.Parse(eventArgument)); OnNumericUpDownEvent(this, nudca); } #endregion } /// <summary> /// Class that adds the prestamoList to the event /// </summary> public class NumericUpDownChangedArgs : System.EventArgs { /// <summary> /// The current selected value. /// </summary> public long Value { get; private set; } public NumericUpDownChangedArgs(long value) { Value = value; } } } using System; using System.Collections.Generic; using System.Text; namespace Corp { /// <summary> /// Summary description for CorpAjaxControlToolkitUserControl /// </summary> public class CorpNumericUpDown : CorpAjaxControlToolkitUserControl { private Int16 _currentInstanceNumber; // This variable hold the instanceNumber assignated at first place. public short currentInstanceNumber { get { return _currentInstanceNumber; } set { _currentInstanceNumber = value; } } protected void Page_PreRender(object sender, EventArgs e) { const string strOnChange = "OnChange"; const string strCallServer = "NumericUpDownCallServer"; StringBuilder str = new StringBuilder(); foreach (KeyValuePair<String, Int16> control in controlsToRegister) { str.Append("function ").Append(strOnChange + control.Value).Append("(sender, eventArgs) ").AppendLine(); str.Append("{").AppendLine(); str.Append(" if (sender) {").AppendLine(); str.Append(" var hfield = document.getElementById('").Append(control.Key).Append("');").AppendLine(); str.Append(" if (hfield.value != eventArgs) {").AppendLine(); str.Append(" hfield.value = eventArgs;").AppendLine(); str.Append(" ").Append(strCallServer + control.Value).Append("(eventArgs, eventArgs);").AppendLine(); str.Append(" }").AppendLine(); str.Append(" }").AppendLine(); str.Append("}").AppendLine(); Page.ClientScript.RegisterClientScriptBlock(typeof(CorpNumericUpDown), Guid.NewGuid().ToString(), str.ToString(), true); } str = new StringBuilder(); foreach (KeyValuePair<String, Int16> control in controlsToRegister) { str.Append(" funcsPageLoad[funcsPageLoad.length] = function() { $find('NumericUpDownEx" + control.Value + "').add_currentChanged(").Append(strOnChange + control.Value).Append(");};").AppendLine(); str.Append(" funcsPageUnLoad[funcsPageUnLoad.length] = function() { $find('NumericUpDownEx" + control.Value + "').remove_currentChanged(").Append(strOnChange + control.Value).Append(");};").AppendLine(); } Page.ClientScript.RegisterClientScriptBlock(typeof(CorpNumericUpDown), Guid.NewGuid().ToString(), str.ToString(), true); } } } and to create the loading view I use this: //The beginRequest event is raised before the processing of an asynchronous postback starts and the postback is sent to the server. You can use this event to call custom script to set a request header or to start an animation that notifies the user that the postback is being processed. Sys.WebForms.PageRequestManager.getInstance().add_beginRequest( function (sender, args) { var modalPopupBehavior = $find('programmaticSavingLoadingModalPopupBehavior'); modalPopupBehavior.show(); } ); //The endRequest event is raised after an asynchronous postback is finished and control has been returned to the browser. You can use this event to provide a notification to users or to log errors. Sys.WebForms.PageRequestManager.getInstance().add_endRequest( function (sender, arg) { var modalPopupBehavior = $find('programmaticSavingLoadingModalPopupBehavior'); modalPopupBehavior.hide(); } ); Thanks in advance! Daniel.

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  • Uneditable file and Unreadable(for further processing) file( WHY? ) after processing it through C++

    - by mgj
    Hi...:) This might look to be a very long question to you I understand, but trust me on this its not long. I am not able to identify why after processing this text is not being able to be read and edited. I tried using the ord() function in python to check if the text contains any Unicode characters( non ascii characters) apart from the ascii ones.. I found quite a number of them. I have a strong feeling that this could be due to the original text itself( The INPUT ). Input-File: Just copy paste it into a file "acle5v1.txt" The objective of this code below is to check for upper case characters and to convert it to lower case and also to remove all punctuations so that these words are taken for further processing for word alignment #include<iostrea> #include<fstream> #include<ctype.h> #include<cstring> using namespace std; ifstream fin2("acle5v1.txt"); ofstream fin3("acle5v1_op.txt"); ofstream fin4("chkcharadded.txt"); ofstream fin5("chkcharntadded.txt"); ofstream fin6("chkprintchar.txt"); ofstream fin7("chknonasci.txt"); ofstream fin8("nonprinchar.txt"); int main() { char ch,ch1; fin2.seekg(0); fin3.seekp(0); int flag = 0; while(!fin2.eof()) { ch1=ch; fin2.get(ch); if (isprint(ch))// if the character is printable flag = 1; if(flag) { fin6<<"Printable character:\t"<<ch<<"\t"<<(int)ch<<endl; flag = 0; } else { fin8<<"Non printable character caught:\t"<<ch<<"\t"<<int(ch)<<endl; } if( isalnum(ch) || ch == '@' || ch == ' ' )// checks for alpha numeric characters { fin4<<"char added: "<<ch<<"\tits ascii value: "<<int(ch)<<endl; if(isupper(ch)) { //tolower(ch); fin3<<(char)tolower(ch); } else { fin3<<ch; } } else if( ( ch=='\t' || ch=='.' || ch==',' || ch=='#' || ch=='?' || ch=='!' || ch=='"' || ch != ';' || ch != ':') && ch1 != ' ' ) { fin3<<' '; } else if( (ch=='\t' || ch=='.' || ch==',' || ch=='#' || ch=='?' || ch=='!' || ch=='"' || ch != ';' || ch != ':') && ch1 == ' ' ) { //fin3<<" '; } else if( !(int(ch)>=0 && int(ch)<=127) ) { fin5<<"Char of ascii within range not added: "<<ch<<"\tits ascii value: "<<int(ch)<<endl; } else { fin7<<"Non ascii character caught(could be a -ve value also)\t"<<ch<<int(ch)<<endl; } } return 0; } I have a similar code as the above written in python which gives me an otput which is again not readable and not editable The code in python looks like this: #!/usr/bin/python # -*- coding: UTF-8 -*- import sys input_file=sys.argv[1] output_file=sys.argv[2] list1=[] f=open(input_file) for line in f: line=line.strip() #line=line.rstrip('.') line=line.replace('.','') line=line.replace(',','') line=line.replace('#','') line=line.replace('?','') line=line.replace('!','') line=line.replace('"','') line=line.replace('?','') line=line.replace('|','') line = line.lower() list1.append(line) f.close() f1=open(output_file,'w') f1.write(' '.join(list1)) f1.close() the file takes ip and op at runtime.. as: python punc_remover.py acle5v1.txt acle5v1_op.txt The output of this file is in "acle5v1_op.txt" now after processing this particular output file is needed for further processing. This particular file "aclee5v1_op.txt" is the UNREADABLE Aand UNEDITABLE File that I am not being able to use for further processing. I need this for Word alignment in NLP. I tried readin this output with the following program #include<iostream> #include<fstream> using namespace std; ifstream fin1("acle5v1_op.txt"); ofstream fout1("chckread_acle5v1_op.txt"); ofstream fout2("chcknotread_acle5v1_op.txt"); int main() { char ch; int flag = 0; long int r = 0; long int nr = 0; while(!(fin1)) { fin1.get(ch); if(ch) { flag = 1; } if(flag) { fout1<<ch; flag = 0; r++; } else { fout2<<"Char not been able to be read from source file\n"; nr++; } } cout<<"Number of characters able to be read: "<<r; cout<<endl<<"Number of characters not been able to be read: "<<nr; return 0; } which prints the character if its readable and if not it doesn't print them but I observed the output of both the file is blank thus I could draw a conclusion that this file "acle5v1_op.txt" is UNREADABLE AND UNEDITABLE. Could you please help me on how to deal with this problem.. To tell you a bit about the statistics wrt the original input file "acle5v1.txt" file it has around 3441 lines in it and around 3 million characters in it. Keeping in mind the number of characters in the file you editor might/might not be able to manage to open the file.. I was able to open the file in gedit of Fedora 10 which I am currently using .. This is just to notify you that opening with a particular editor was not actually an issue at least in my case... Can I use scripting languages like Python and Perl to deal with this problem if Yes how? could please be specific on that regard as I am a novice to Perl and Python. Or could you please tell me how do I solve this problem using C++ itself.. Thank you...:) I am really looking forward to some help or guidance on how to go about this problem....

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  • I am trying to insert value from combo box to database !! but this is not working

    - by user3675488
    At first I have taken some string in which I am trying to save the input values of textboxs and there is a combo box, I am trying to save the input value of the combo box to database, but this following code is unable to do that !!! what is the prob please help me. private void OK_Click(object sender, EventArgs e) { string sTxtcmpnyName = ""; string sTxtcmpnyAdd = ""; string sPhoneno = ""; string sTxtFax = ""; string sPanNo = ""; string sTxtTin = ""; string sTax = ""; string sAccYr = ""; string sComboSt = ""; foreach (Control c in this.Controls) ////*Adding Validation to the textbox.*// // Here the control is entered into GroupBox Grpcmp where c is denoting the name of the control into the groupbox. { // c1 is another control which denotes the textboxes under the GroupBox Grpcmp. foreach (Control c1 in c.Controls) { /////Now this following code snippets reperesents that the name of the company should not be blank. if (c1 is TextBox == true) // simpler that what you've done there { TextBox temp = (TextBox)c1; //The control is entering into Txtcompany. if (temp.Name == "Txtcompanyname") { //Condition checking is the TextBox is empty or Null then the following message will be shown. if ((temp.Text == "") || (temp.Text == "NULL")) { MessageBox.Show("Company Name should not be Blank"); } sTxtcmpnyName = temp.Text; } else if (c1.Name == "TxtcompanyAddress") { sTxtcmpnyAdd = c1.Text; } else if (c1.Name == "Txtphoneno") { sPhoneno = c1.Text; } else if (c1.Name == "TxtFax ") { sTxtFax = c1.Text; } else if (c1.Name == "Txtpanno") { sPanNo = c1.Text; } else if (c1.Name == "TxtTin") { sTxtTin = c1.Text; } else if (c1.Name == "Txtservicetax") { sTax = c1.Text; } //Now I am converting the TxtAcYr into Date format. //For this purpose two conditions are checked first. //First If the TextBox TxtAcYr is Null or empty it will show the message to enter the accountyear!! //Second If the length of the TextBox TxtAcYr is less than 10, it will again generate a message The date format should be in DD/MM/YYYY // Then the value of the use input will be picked using a For loop. if (c1.Name == "TxtAcYr") { sAccYr = c1.Text; //Here a string is taken named as yearlength and the value of the TxtAcYr is assigned to it by using control c1. //Condition Checking If the TextBox TxtAcYr is Null or empty it will show the message to enter the accountyear!! if ((c1.Text == "") || (c1.Text == "NULL")) { MessageBox.Show("Account Year should be entered!!"); } //Condition 2 is checking. Here the length of the string yearlength is whether equals to 10 or not is checked. //Because there are total 10 characters in Date Format along with special character. else // MessageBox.Show(yearlength.Length.ToString()); if (sAccYr.Length != 10) { MessageBox.Show("The Data Format DD-MM-YYYY"); } //Now the value of user will be picked by using the code snippets. else { //A string named as JK is taken for further use. String JK = ""; //This following loop is initiated to pick the user input. //The loop will check wheather the value of i is less than the length of string yearlength or not. //If Yes then it will go further. for (int i = 0; i < sAccYr.Length; i++) { //This condition is checking special characters. //The positions of special characters(Here '-') are placed at 2nd and 5th numbers. //So, the value of i can not be equals to 2 && 5. if ((i != 2) && (i != 5)) { //The new of value of year length i is assinged to the variable JK. JK = JK + sAccYr[i]; } //If the value of i is equals to 1, then enter the following. if (i == 1) { //*Should add the function of TOInt32* // If ToInt32(JK)>= the maximum length of days of a month then the following alert message will be shown. if (Convert.ToInt32(JK) >= 32) { MessageBox.Show("The Data Format DD-MM-YYYY"); } //**Comment should be added.** JK = ""; } else //If the value of i is equals to 4, then enter the following. if (i == 4) { //*Should add the function of TOInt32* // If ToInt32(JK)>= the maximum length of month then the following alert message will be shown. if (Convert.ToInt32(JK) >= 13) { MessageBox.Show("The Data Format DD-MM-YYYY"); } JK = ""; } } } } } else if (c1.Name == "state_cmb") { //sTxttate = c1.Text.ToString(); sComboSt = c1.Text; MessageBox.Show(c1.Text); } } } //////DATABASE CONNECTION///// try { SqlConnection conn = new SqlConnection(); SqlCommand cmd = new SqlCommand(); conn.ConnectionString = ("Data Source =192.168.0.2 ;database= Mee_Company; Persist Security Info =true; User ID =sa;Password = soso654321@"); conn.Open(); cmd.CommandText = ("INSERT INTO CompanyMaster(CompanyName,Address,State,Phone,Fax,PAN,TIN,STAX,AccountsYear)values('" + sTxtcmpnyName + "','" + sTxtcmpnyAdd + "','" + sComboSt + "','" + sPhoneno + "','" + sTxtFax + "','" + sPanNo + "','" + sTxtTin + "','" + sTax + "','" + sAccYr + "')"); //('" + sTxtcmpnyName + "', '" + TxtcompanyAddress.Text + "', '" + Txtphoneno.Text + "', '" + TxtFax.Text + "', '" + Txtservicetax.Text + "','" + TxtAcYr.Text + "')"); cmd.Connection = conn; cmd.ExecuteNonQuery(); conn.Close(); //cmd.Parameters.AddWithValue } catch (Exception ee) { MessageBox.Show(ee.ToString()); } } //An event is created here so that when the user will click on the Cancel Button, the Form will be closed. private void BtmCancle_Click(object sender, EventArgs e) { //this means the form. this.Close(); } //Another Event is created here named as TxtAcYr_KeyPress. //It is for making the TextBox TxtAcYr only allowance of numeric input along with special character '-'. private void TxtAcYr_KeyPress(object sender, KeyPressEventArgs e) { //If the input is number or '-' is checked //And also the backspace and delete option is enabled here. if (char.IsNumber(e.KeyChar) || e.KeyChar == (char)Keys.Back || e.KeyChar == (char)Keys.Delete || e.KeyChar == '-') { e.Handled = false; //ok } else { e.Handled = true; //not ok } }

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  • C++ function not found during compilation

    - by forthewinwin
    For a homework assignment: I'm supposed to create randomized alphabetial keys, print them to a file, and then hash each of them into a hash table using the function "goodHash", found in my below code. When I try to run the below code, it says my "goodHash" "identifier isn't found". What's wrong with my code? #include <iostream> #include <vector> #include <cstdlib> #include "math.h" #include <fstream> #include <time.h> using namespace std; // "makeKey" function to create an alphabetical key // based on 8 randomized numbers 0 - 25. string makeKey() { int k; string key = ""; for (k = 0; k < 8; k++) { int keyNumber = (rand() % 25); if (keyNumber == 0) key.append("A"); if (keyNumber == 1) key.append("B"); if (keyNumber == 2) key.append("C"); if (keyNumber == 3) key.append("D"); if (keyNumber == 4) key.append("E"); if (keyNumber == 5) key.append("F"); if (keyNumber == 6) key.append("G"); if (keyNumber == 7) key.append("H"); if (keyNumber == 8) key.append("I"); if (keyNumber == 9) key.append("J"); if (keyNumber == 10) key.append("K"); if (keyNumber == 11) key.append("L"); if (keyNumber == 12) key.append("M"); if (keyNumber == 13) key.append("N"); if (keyNumber == 14) key.append("O"); if (keyNumber == 15) key.append("P"); if (keyNumber == 16) key.append("Q"); if (keyNumber == 17) key.append("R"); if (keyNumber == 18) key.append("S"); if (keyNumber == 19) key.append("T"); if (keyNumber == 20) key.append("U"); if (keyNumber == 21) key.append("V"); if (keyNumber == 22) key.append("W"); if (keyNumber == 23) key.append("X"); if (keyNumber == 24) key.append("Y"); if (keyNumber == 25) key.append("Z"); } return key; } // "makeFile" function to produce the desired text file. // Note this only works as intended if you include the ".txt" extension, // and that a file of the same name doesn't already exist. void makeFile(string fileName, int n) { ofstream ourFile; ourFile.open(fileName); int k; // For use in below loop to compare with n. int l; // For use in the loop inside the below loop. string keyToPassTogoodHash = ""; for (k = 1; k <= n; k++) { for (l = 0; l < 8; l++) { // For-loop to write to the file ONE key ourFile << makeKey()[l]; keyToPassTogoodHash += (makeKey()[l]); } ourFile << " " << k << "\n";// Writes two spaces and the data value goodHash(keyToPassTogoodHash); // I think this has to do with the problem makeKey(); // Call again to make a new key. } } // Primary function to create our desired file! void mainFunction(string fileName, int n) { makeKey(); makeFile(fileName, n); } // Hash Table for Part 2 struct Node { int key; string value; Node* next; }; const int hashTableSize = 10; Node* hashTable[hashTableSize]; // "goodHash" function for Part 2 void goodHash(string key) { int x = 0; int y; int keyConvertedToNumber = 0; // For-loop to produce a numeric value based on the alphabetic key, // which is then hashed into hashTable using the hash function // declared below the loop (hashFunction). for (y = 0; y < 8; y++) { if (key[y] == 'A' || 'B' || 'C') x = 0; if (key[y] == 'D' || 'E' || 'F') x = 1; if (key[y] == 'G' || 'H' || 'I') x = 2; if (key[y] == 'J' || 'K' || 'L') x = 3; if (key[y] == 'M' || 'N' || 'O') x = 4; if (key[y] == 'P' || 'Q' || 'R') x = 5; if (key[y] == 'S' || 'T') x = 6; if (key[y] == 'U' || 'V') x = 7; if (key[y] == 'W' || 'X') x = 8; if (key[y] == 'Y' || 'Z') x = 9; keyConvertedToNumber = x + keyConvertedToNumber; } int hashFunction = keyConvertedToNumber % hashTableSize; Node *temp; temp = new Node; temp->value = key; temp->next = hashTable[hashFunction]; hashTable[hashFunction] = temp; } // First two lines are for Part 1, to call the functions key to Part 1. int main() { srand ( time(NULL) ); // To make sure our randomization works. mainFunction("sandwich.txt", 5); // To test program cin.get(); return 0; } I realize my code is cumbersome in some sections, but I'm a noob at C++ and don't know much to do it better. I'm guessing another way I could do it is to AFTER writing the alphabetical keys to the file, read them from the file and hash each key as I do that, but I wouldn't know how to go about coding that.

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  • How to autostart this slide

    - by lchales
    Hello there: first of all i have no idea on coding or anything related, simple question: is there any simple way to tell this code to autostart the slide? at the current moment the images change on click. currently the index page only have one image, what i want is to add a few but without the need to click to see the next one here is the code from my index: <script type="text/javascript"> //<![CDATA[ /* the images preload plugin */ (function($) { $.fn.preload = function(options) { var opts = $.extend({}, $.fn.preload.defaults, options), o = $.meta ? $.extend({}, opts, this.data()) : opts; var c = this.length, l = 0; return this.each(function() { var $i = $(this); $('<img/>').load(function(i){ ++l; if(l == c) o.onComplete(); }).attr('src',$i.attr('src')); }); }; $.fn.preload.defaults = { onComplete : function(){return false;} }; })(jQuery); //]]> </script><script type="text/javascript"> //<![CDATA[ $(function() { var $tf_bg = $('#tf_bg'), $tf_bg_images = $tf_bg.find('img'), $tf_bg_img = $tf_bg_images.eq(0), $tf_thumbs = $('#tf_thumbs'), total = $tf_bg_images.length, current = 0, $tf_content_wrapper = $('#tf_content_wrapper'), $tf_next = $('#tf_next'), $tf_prev = $('#tf_prev'), $tf_loading = $('#tf_loading'); //preload the images $tf_bg_images.preload({ onComplete : function(){ $tf_loading.hide(); init(); } }); //shows the first image and initializes events function init(){ //get dimentions for the image, based on the windows size var dim = getImageDim($tf_bg_img); //set the returned values and show the image $tf_bg_img.css({ width : dim.width, height : dim.height, left : dim.left, top : dim.top }).fadeIn(); //resizing the window resizes the $tf_bg_img $(window).bind('resize',function(){ var dim = getImageDim($tf_bg_img); $tf_bg_img.css({ width : dim.width, height : dim.height, left : dim.left, top : dim.top }); }); //expand and fit the image to the screen $('#tf_zoom').live('click', function(){ if($tf_bg_img.is(':animated')) return false; var $this = $(this); if($this.hasClass('tf_zoom')){ resize($tf_bg_img); $this.addClass('tf_fullscreen') .removeClass('tf_zoom'); } else{ var dim = getImageDim($tf_bg_img); $tf_bg_img.animate({ width : dim.width, height : dim.height, top : dim.top, left : dim.left },350); $this.addClass('tf_zoom') .removeClass('tf_fullscreen'); } } ); //click the arrow down, scrolls down $tf_next.bind('click',function(){ if($tf_bg_img.is(':animated')) return false; scroll('tb'); }); //click the arrow up, scrolls up $tf_prev.bind('click',function(){ if($tf_bg_img.is(':animated')) return false; scroll('bt'); }); //mousewheel events - down / up button trigger the scroll down / up $(document).mousewheel(function(e, delta) { if($tf_bg_img.is(':animated')) return false; if(delta > 0) scroll('bt'); else scroll('tb'); return false; }); //key events - down / up button trigger the scroll down / up $(document).keydown(function(e){ if($tf_bg_img.is(':animated')) return false; switch(e.which){ case 38: scroll('bt'); break; case 40: scroll('tb'); break; } }); } //show next / prev image function scroll(dir){ //if dir is "tb" (top -> bottom) increment current, //else if "bt" decrement it current = (dir == 'tb')?current + 1:current - 1; //we want a circular slideshow, //so we need to check the limits of current if(current == total) current = 0; else if(current < 0) current = total - 1; //flip the thumb $tf_thumbs.flip({ direction : dir, speed : 400, onBefore : function(){ //the new thumb is set here var content = '<span id="tf_zoom" class="tf_zoom"><\/span>'; content +='<img src="' + $tf_bg_images.eq(current).attr('longdesc') + '" alt="Thumb' + (current+1) + '"/>'; $tf_thumbs.html(content); } }); //we get the next image var $tf_bg_img_next = $tf_bg_images.eq(current), //its dimentions dim = getImageDim($tf_bg_img_next), //the top should be one that makes the image out of the viewport //the image should be positioned up or down depending on the direction top = (dir == 'tb')?$(window).height() + 'px':-parseFloat(dim.height,10) + 'px'; //set the returned values and show the next image $tf_bg_img_next.css({ width : dim.width, height : dim.height, left : dim.left, top : top }).show(); //now slide it to the viewport $tf_bg_img_next.stop().animate({ top : dim.top },700); //we want the old image to slide in the same direction, out of the viewport var slideTo = (dir == 'tb')?-$tf_bg_img.height() + 'px':$(window).height() + 'px'; $tf_bg_img.stop().animate({ top : slideTo },700,function(){ //hide it $(this).hide(); //the $tf_bg_img is now the shown image $tf_bg_img = $tf_bg_img_next; //show the description for the new image $tf_content_wrapper.children() .eq(current) .show(); }); //hide the current description $tf_content_wrapper.children(':visible') .hide() } //animate the image to fit in the viewport function resize($img){ var w_w = $(window).width(), w_h = $(window).height(), i_w = $img.width(), i_h = $img.height(), r_i = i_h / i_w, new_w,new_h; if(i_w > i_h){ new_w = w_w; new_h = w_w * r_i; if(new_h > w_h){ new_h = w_h; new_w = w_h / r_i; } } else{ new_h = w_w * r_i; new_w = w_w; } $img.animate({ width : new_w + 'px', height : new_h + 'px', top : '0px', left : '0px' },350); } //get dimentions of the image, //in order to make it full size and centered function getImageDim($img){ var w_w = $(window).width(), w_h = $(window).height(), r_w = w_h / w_w, i_w = $img.width(), i_h = $img.height(), r_i = i_h / i_w, new_w,new_h, new_left,new_top; if(r_w > r_i){ new_h = w_h; new_w = w_h / r_i; } else{ new_h = w_w * r_i; new_w = w_w; } return { width : new_w + 'px', height : new_h + 'px', left : (w_w - new_w) / 2 + 'px', top : (w_h - new_h) / 2 + 'px' }; } }); //]]> </script>

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  • Using HTML 5 SessionState to save rendered Page Content

    - by Rick Strahl
    HTML 5 SessionState and LocalStorage are very useful and super easy to use to manage client side state. For building rich client side or SPA style applications it's a vital feature to be able to cache user data as well as HTML content in order to swap pages in and out of the browser's DOM. What might not be so obvious is that you can also use the sessionState and localStorage objects even in classic server rendered HTML applications to provide caching features between pages. These APIs have been around for a long time and are supported by most relatively modern browsers and even all the way back to IE8, so you can use them safely in your Web applications. SessionState and LocalStorage are easy The APIs that make up sessionState and localStorage are very simple. Both object feature the same API interface which  is a simple, string based key value store that has getItem, setItem, removeitem, clear and  key methods. The objects are also pseudo array objects and so can be iterated like an array with  a length property and you have array indexers to set and get values with. Basic usage  for storing and retrieval looks like this (using sessionStorage, but the syntax is the same for localStorage - just switch the objects):// set var lastAccess = new Date().getTime(); if (sessionStorage) sessionStorage.setItem("myapp_time", lastAccess.toString()); // retrieve in another page or on a refresh var time = null; if (sessionStorage) time = sessionStorage.getItem("myapp_time"); if (time) time = new Date(time * 1); else time = new Date(); sessionState stores data that is browser session specific and that has a liftetime of the active browser session or window. Shut down the browser or tab and the storage goes away. localStorage uses the same API interface, but the lifetime of the data is permanently stored in the browsers storage area until deleted via code or by clearing out browser cookies (not the cache). Both sessionStorage and localStorage space is limited. The spec is ambiguous about this - supposedly sessionStorage should allow for unlimited size, but it appears that most WebKit browsers support only 2.5mb for either object. This means you have to be careful what you store especially since other applications might be running on the same domain and also use the storage mechanisms. That said 2.5mb worth of character data is quite a bit and would go a long way. The easiest way to get a feel for how sessionState and localStorage work is to look at a simple example. You can go check out the following example online in Plunker: http://plnkr.co/edit/0ICotzkoPjHaWa70GlRZ?p=preview which looks like this: Plunker is an online HTML/JavaScript editor that lets you write and run Javascript code and similar to JsFiddle, but a bit cleaner to work in IMHO (thanks to John Papa for turning me on to it). The sample has two text boxes with counts that update session/local storage every time you click the related button. The counts are 'cached' in Session and Local storage. The point of these examples is that both counters survive full page reloads, and the LocalStorage counter survives a complete browser shutdown and restart. Go ahead and try it out by clicking the Reload button after updating both counters and then shutting down the browser completely and going back to the same URL (with the same browser). What you should see is that reloads leave both counters intact at the counted values, while a browser restart will leave only the local storage counter intact. The code to deal with the SessionStorage (and LocalStorage not shown here) in the example is isolated into a couple of wrapper methods to simplify the code: function getSessionCount() { var count = 0; if (sessionStorage) { var count = sessionStorage.getItem("ss_count"); count = !count ? 0 : count * 1; } $("#txtSession").val(count); return count; } function setSessionCount(count) { if (sessionStorage) sessionStorage.setItem("ss_count", count.toString()); } These two functions essentially load and store a session counter value. The two key methods used here are: sessionStorage.getItem(key); sessionStorage.setItem(key,stringVal); Note that the value given to setItem and return by getItem has to be a string. If you pass another type you get an error. Don't let that limit you though - you can easily enough store JSON data in a variable so it's quite possible to pass complex objects and store them into a single sessionStorage value:var user = { name: "Rick", id="ricks", level=8 } sessionStorage.setItem("app_user",JSON.stringify(user)); to retrieve it:var user = sessionStorage.getItem("app_user"); if (user) user = JSON.parse(user); Simple! If you're using the Chrome Developer Tools (F12) you can also check out the session and local storage state on the Resource tab:   You can also use this tool to refresh or remove entries from storage. What we just looked at is a purely client side implementation where a couple of counters are stored. For rich client centric AJAX applications sessionStorage and localStorage provide a very nice and simple API to store application state while the application is running. But you can also use these storage mechanisms to manage server centric HTML applications when you combine server rendering with some JavaScript to perform client side data caching. You can both store some state information and data on the client (ie. store a JSON object and carry it forth between server rendered HTML requests) or you can use it for good old HTTP based caching where some rendered HTML is saved and then restored later. Let's look at the latter with a real life example. Why do I need Client-side Page Caching for Server Rendered HTML? I don't know about you, but in a lot of my existing server driven applications I have lists that display a fair amount of data. Typically these lists contain links to then drill down into more specific data either for viewing or editing. You can then click on a link and go off to a detail page that provides more concise content. So far so good. But now you're done with the detail page and need to get back to the list, so you click on a 'bread crumbs trail' or an application level 'back to list' button and… …you end up back at the top of the list - the scroll position, the current selection in some cases even filters conditions - all gone with the wind. You've left behind the state of the list and are starting from scratch in your browsing of the list from the top. Not cool! Sound familiar? This a pretty common scenario with server rendered HTML content where it's so common to display lists to drill into, only to lose state in the process of returning back to the original list. Look at just about any traditional forums application, or even StackOverFlow to see what I mean here. Scroll down a bit to look at a post or entry, drill in then use the bread crumbs or tab to go back… In some cases returning to the top of a list is not a big deal. On StackOverFlow that sort of works because content is turning around so quickly you probably want to actually look at the top posts. Not always though - if you're browsing through a list of search topics you're interested in and drill in there's no way back to that position. Essentially anytime you're actively browsing the items in the list, that's when state becomes important and if it's not handled the user experience can be really disrupting. Content Caching If you're building client centric SPA style applications this is a fairly easy to solve problem - you tend to render the list once and then update the page content to overlay the detail content, only hiding the list temporarily until it's used again later. It's relatively easy to accomplish this simply by hiding content on the page and later making it visible again. But if you use server rendered content, hanging on to all the detail like filters, selections and scroll position is not quite as easy. Or is it??? This is where sessionStorage comes in handy. What if we just save the rendered content of a previous page, and then restore it when we return to this page based on a special flag that tells us to use the cached version? Let's see how we can do this. A real World Use Case Recently my local ISP asked me to help out with updating an ancient classifieds application. They had a very busy, local classifieds app that was originally an ASP classic application. The old app was - wait for it: frames based - and even though I lobbied against it, the decision was made to keep the frames based layout to allow rapid browsing of the hundreds of posts that are made on a daily basis. The primary reason they wanted this was precisely for the ability to quickly browse content item by item. While I personally hate working with Frames, I have to admit that the UI actually works well with the frames layout as long as you're running on a large desktop screen. You can check out the frames based desktop site here: http://classifieds.gorge.net/ However when I rebuilt the app I also added a secondary view that doesn't use frames. The main reason for this of course was for mobile displays which work horribly with frames. So there's a somewhat mobile friendly interface to the interface, which ditches the frames and uses some responsive design tweaking for mobile capable operation: http://classifeds.gorge.net/mobile  (or browse the base url with your browser width under 800px)   Here's what the mobile, non-frames view looks like:   As you can see this means that the list of classifieds posts now is a list and there's a separate page for drilling down into the item. And of course… originally we ran into that usability issue I mentioned earlier where the browse, view detail, go back to the list cycle resulted in lost list state. Originally in mobile mode you scrolled through the list, found an item to look at and drilled in to display the item detail. Then you clicked back to the list and BAM - you've lost your place. Because there are so many items added on a daily basis the full list is never fully loaded, but rather there's a "Load Additional Listings"  entry at the button. Not only did we originally lose our place when coming back to the list, but any 'additionally loaded' items are no longer there because the list was now rendering  as if it was the first page hit. The additional listings, and any filters, the selection of an item all were lost. Major Suckage! Using Client SessionStorage to cache Server Rendered Content To work around this problem I decided to cache the rendered page content from the list in SessionStorage. Anytime the list renders or is updated with Load Additional Listings, the page HTML is cached and stored in Session Storage. Any back links from the detail page or the login or write entry forms then point back to the list page with a back=true query string parameter. If the server side sees this parameter it doesn't render the part of the page that is cached. Instead the client side code retrieves the data from the sessionState cache and simply inserts it into the page. It sounds pretty simple, and the overall the process is really easy, but there are a few gotchas that I'll discuss in a minute. But first let's look at the implementation. Let's start with the server side here because that'll give a quick idea of the doc structure. As I mentioned the server renders data from an ASP.NET MVC view. On the list page when returning to the list page from the display page (or a host of other pages) looks like this: https://classifieds.gorge.net/list?back=True The query string value is a flag, that indicates whether the server should render the HTML. Here's what the top level MVC Razor view for the list page looks like:@model MessageListViewModel @{ ViewBag.Title = "Classified Listing"; bool isBack = !string.IsNullOrEmpty(Request.QueryString["back"]); } <form method="post" action="@Url.Action("list")"> <div id="SizingContainer"> @if (!isBack) { @Html.Partial("List_CommandBar_Partial", Model) <div id="PostItemContainer" class="scrollbox" xstyle="-webkit-overflow-scrolling: touch;"> @Html.Partial("List_Items_Partial", Model) @if (Model.RequireLoadEntry) { <div class="postitem loadpostitems" style="padding: 15px;"> <div id="LoadProgress" class="smallprogressright"></div> <div class="control-progress"> Load additional listings... </div> </div> } </div> } </div> </form> As you can see the query string triggers a conditional block that if set is simply not rendered. The content inside of #SizingContainer basically holds  the entire page's HTML sans the headers and scripts, but including the filter options and menu at the top. In this case this makes good sense - in other situations the fact that the menu or filter options might be dynamically updated might make you only cache the list rather than essentially the entire page. In this particular instance all of the content works and produces the proper result as both the list along with any filter conditions in the form inputs are restored. Ok, let's move on to the client. On the client there are two page level functions that deal with saving and restoring state. Like the counter example I showed earlier, I like to wrap the logic to save and restore values from sessionState into a separate function because they are almost always used in several places.page.saveData = function(id) { if (!sessionStorage) return; var data = { id: id, scroll: $("#PostItemContainer").scrollTop(), html: $("#SizingContainer").html() }; sessionStorage.setItem("list_html",JSON.stringify(data)); }; page.restoreData = function() { if (!sessionStorage) return; var data = sessionStorage.getItem("list_html"); if (!data) return null; return JSON.parse(data); }; The data that is saved is an object which contains an ID which is the selected element when the user clicks and a scroll position. These two values are used to reset the scroll position when the data is used from the cache. Finally the html from the #SizingContainer element is stored, which makes for the bulk of the document's HTML. In this application the HTML captured could be a substantial bit of data. If you recall, I mentioned that the server side code renders a small chunk of data initially and then gets more data if the user reads through the first 50 or so items. The rest of the items retrieved can be rather sizable. Other than the JSON deserialization that's Ok. Since I'm using SessionStorage the storage space has no immediate limits. Next is the core logic to handle saving and restoring the page state. At first though this would seem pretty simple, and in some cases it might be, but as the following code demonstrates there are a few gotchas to watch out for. Here's the relevant code I use to save and restore:$( function() { … var isBack = getUrlEncodedKey("back", location.href); if (isBack) { // remove the back key from URL setUrlEncodedKey("back", "", location.href); var data = page.restoreData(); // restore from sessionState if (!data) { // no data - force redisplay of the server side default list window.location = "list"; return; } $("#SizingContainer").html(data.html); var el = $(".postitem[data-id=" + data.id + "]"); $(".postitem").removeClass("highlight"); el.addClass("highlight"); $("#PostItemContainer").scrollTop(data.scroll); setTimeout(function() { el.removeClass("highlight"); }, 2500); } else if (window.noFrames) page.saveData(null); // save when page loads $("#SizingContainer").on("click", ".postitem", function() { var id = $(this).attr("data-id"); if (!id) return true; if (window.noFrames) page.saveData(id); var contentFrame = window.parent.frames["Content"]; if (contentFrame) contentFrame.location.href = "show/" + id; else window.location.href = "show/" + id; return false; }); … The code starts out by checking for the back query string flag which triggers restoring from the client cache. If cached the cached data structure is read from sessionStorage. It's important here to check if data was returned. If the user had back=true on the querystring but there is no cached data, he likely bookmarked this page or otherwise shut down the browser and came back to this URL. In that case the server didn't render any detail and we have no cached data, so all we can do is redirect to the original default list view using window.location. If we continued the page would render no data - so make sure to always check the cache retrieval result. Always! If there is data the it's loaded and the data.html data is restored back into the document by simply injecting the HTML back into the document's #SizingContainer element:$("#SizingContainer").html(data.html); It's that simple and it's quite quick even with a fully loaded list of additional items and on a phone. The actual HTML data is stored to the cache on every page load initially and then again when the user clicks on an element to navigate to a particular listing. The former ensures that the client cache always has something in it, and the latter updates with additional information for the selected element. For the click handling I use a data-id attribute on the list item (.postitem) in the list and retrieve the id from that. That id is then used to navigate to the actual entry as well as storing that Id value in the saved cached data. The id is used to reset the selection by searching for the data-id value in the restored elements. The overall process of this save/restore process is pretty straight forward and it doesn't require a bunch of code, yet it yields a huge improvement in the usability of the site on mobile devices (or anybody who uses the non-frames view). Some things to watch out for As easy as it conceptually seems to simply store and retrieve cached content, you have to be quite aware what type of content you are caching. The code above is all that's specific to cache/restore cycle and it works, but it took a few tweaks to the rest of the script code and server code to make it all work. There were a few gotchas that weren't immediately obvious. Here are a few things to pay attention to: Event Handling Logic Timing of manipulating DOM events Inline Script Code Bookmarking to the Cache Url when no cache exists Do you have inline script code in your HTML? That script code isn't going to run if you restore from cache and simply assign or it may not run at the time you think it would normally in the DOM rendering cycle. JavaScript Event Hookups The biggest issue I ran into with this approach almost immediately is that originally I had various static event handlers hooked up to various UI elements that are now cached. If you have an event handler like:$("#btnSearch").click( function() {…}); that works fine when the page loads with server rendered HTML, but that code breaks when you now load the HTML from cache. Why? Because the elements you're trying to hook those events to may not actually be there - yet. Luckily there's an easy workaround for this by using deferred events. With jQuery you can use the .on() event handler instead:$("#SelectionContainer").on("click","#btnSearch", function() {…}); which monitors a parent element for the events and checks for the inner selector elements to handle events on. This effectively defers to runtime event binding, so as more items are added to the document bindings still work. For any cached content use deferred events. Timing of manipulating DOM Elements Along the same lines make sure that your DOM manipulation code follows the code that loads the cached content into the page so that you don't manipulate DOM elements that don't exist just yet. Ideally you'll want to check for the condition to restore cached content towards the top of your script code, but that can be tricky if you have components or other logic that might not all run in a straight line. Inline Script Code Here's another small problem I ran into: I use a DateTime Picker widget I built a while back that relies on the jQuery date time picker. I also created a helper function that allows keyboard date navigation into it that uses JavaScript logic. Because MVC's limited 'object model' the only way to embed widget content into the page is through inline script. This code broken when I inserted the cached HTML into the page because the script code was not available when the component actually got injected into the page. As the last bullet - it's a matter of timing. There's no good work around for this - in my case I pulled out the jQuery date picker and relied on native <input type="date" /> logic instead - a better choice these days anyway, especially since this view is meant to be primarily to serve mobile devices which actually support date input through the browser (unlike desktop browsers of which only WebKit seems to support it). Bookmarking Cached Urls When you cache HTML content you have to make a decision whether you cache on the client and also not render that same content on the server. In the Classifieds app I didn't render server side content so if the user comes to the page with back=True and there is no cached content I have to a have a Plan B. Typically this happens when somebody ends up bookmarking the back URL. The easiest and safest solution for this scenario is to ALWAYS check the cache result to make sure it exists and if not have a safe URL to go back to - in this case to the plain uncached list URL which amounts to effectively redirecting. This seems really obvious in hindsight, but it's easy to overlook and not see a problem until much later, when it's not obvious at all why the page is not rendering anything. Don't use <body> to replace Content Since we're practically replacing all the HTML in the page it may seem tempting to simply replace the HTML content of the <body> tag. Don't. The body tag usually contains key things that should stay in the page and be there when it loads. Specifically script tags and elements and possibly other embedded content. It's best to create a top level DOM element specifically as a placeholder container for your cached content and wrap just around the actual content you want to replace. In the app above the #SizingContainer is that container. Other Approaches The approach I've used for this application is kind of specific to the existing server rendered application we're running and so it's just one approach you can take with caching. However for server rendered content caching this is a pattern I've used in a few apps to retrofit some client caching into list displays. In this application I took the path of least resistance to the existing server rendering logic. Here are a few other ways that come to mind: Using Partial HTML Rendering via AJAXInstead of rendering the page initially on the server, the page would load empty and the client would render the UI by retrieving the respective HTML and embedding it into the page from a Partial View. This effectively makes the initial rendering and the cached rendering logic identical and removes the server having to decide whether this request needs to be rendered or not (ie. not checking for a back=true switch). All the logic related to caching is made on the client in this case. Using JSON Data and Client RenderingThe hardcore client option is to do the whole UI SPA style and pull data from the server and then use client rendering or databinding to pull the data down and render using templates or client side databinding with knockout/angular et al. As with the Partial Rendering approach the advantage is that there's no difference in the logic between pulling the data from cache or rendering from scratch other than the initial check for the cache request. Of course if the app is a  full on SPA app, then caching may not be required even - the list could just stay in memory and be hidden and reactivated. I'm sure there are a number of other ways this can be handled as well especially using  AJAX. AJAX rendering might simplify the logic, but it also complicates search engine optimization since there's no content loaded initially. So there are always tradeoffs and it's important to look at all angles before deciding on any sort of caching solution in general. State of the Session SessionState and LocalStorage are easy to use in client code and can be integrated even with server centric applications to provide nice caching features of content and data. In this post I've shown a very specific scenario of storing HTML content for the purpose of remembering list view data and state and making the browsing experience for lists a bit more friendly, especially if there's dynamically loaded content involved. If you haven't played with sessionStorage or localStorage I encourage you to give it a try. There's a lot of cool stuff that you can do with this beyond the specific scenario I've covered here… Resources Overview of localStorage (also applies to sessionStorage) Web Storage Compatibility Modernizr Test Suite© Rick Strahl, West Wind Technologies, 2005-2013Posted in JavaScript  HTML5  ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (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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