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• Sending emails in web applications

  - by Denise

  Hi everyone, I'm looking for some opinions here, I'm building a web application which has the fairly standard functionality of: Register for an account by filling out a form and submitting it. Receive an email with a confirmation code link Click the link to confirm the new account and log in When you send emails from your web application, it's often (usually) the case that there will be some change to the persistence layer. For example: A new user registers for an account on your site - the new user is created in the database and an email is sent to them with a confirmation link A user assigns a bug or issue to someone else - the issue is updated and email notifications are sent. How you send these emails can be critical to the success of your application. How you send them depends on how important it is that the intended recipient receives the email. We'll look at the following four strategies in relation to the case where the mail server is down, using example 1. TRANSACTIONAL & SYNCHRONOUS The sending of the email fails and the user is shown an error message saying that their account could not be created. The application will appear to be slow and unresponsive as the application waits for the connection timeout. The account is not created in the database because the transaction is rolled back. TRANSACTIONAL & ASYNCHRONOUS The transactional definition here refers to sending the email to a JMS queue or saving it in a database table for another background process to pick up and send. The user account is created in the database, the email is sent to a JMS queue for processing later. The transaction is successful and committed. The user is shown a message saying that their account was created and to check their email for a confirmation link. It's possible in this case that the email is never sent due to some other error, however the user is told that the email has been sent to them. There may be some delay in getting the email sent to the user if application support has to be called in to diagnose the email problem. NON-TRANSACTIONAL & SYNCHRONOUS The user is created in the database, but the application gets a timeout error when it tries to send the email with the confirmation link. The user is shown an error message saying that there was an error. The application is slow and unresponsive as it waits for the connection timeout When the mail server comes back to life and the user tries to register again, they are told their account already exists but has not been confirmed and are given the option of having the email re-sent to them. NON-TRANSACTIONAL & ASYNCHRONOUS The only difference between this and transactional & asynchronous is that if there is an error sending the email to the JMS queue or saving it in the database, the user account is still created but the email is never sent until the user attempts to register again. What I'd like to know is what have other people done here? Can you recommend any other solutions other than the 4 I've mentioned above? What's a reasonable way of approaching this problem? I don't want to over-engineer a system that's dealing with the (hopefully) rare situation where my mail server goes down! The simplest thing to do is to code it synchronously, but are there any other pitfalls to this approach? I guess I'm wondering if there's a best practice, I couldn't find much out there by googling.

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• php script dies when it calls a bash script, maybe a problem of server configuration

  - by user347501

  Hi!!! I have some problems with a PHP script that calls a Bash script.... in the PHP script is uploaded a XML file, then the PHP script calls a Bash script that cut the file in portions (for example, is uploaded a XML file of 30,000 lines, so the Bash script cut the file in portions of 10,000 lines, so it will be 3 files of 10,000 each one) The file is uploaded, the Bash script cut the lines, but when the Bash script returns to the PHP script, the PHP script dies, & I dont know why... I tested the script in another server and it works fine... I dont believe that is a memory problem, maybe it is a processor problem, I dont know, I dont know what to do, what can I do??? (Im using the function shell_exec in PHP to call the Bash script) The error only happens if the XML file has more than 8,000 lines, but if the file has less then 8,000 everything is ok (this is relative, it depends of the amount of data, of strings, of letters that contains each line) what can you suggest me??? (sorry for my bad english, I have to practice a lot xD) I leave the code here PHP script (at the end, after the ?, there is html & javascript code, but it doesnt appear, only the javascript code... basically the html is only to upload the file) " . date('c') . ": $str"; $file = fopen("uploadxmltest.debug.txt","a"); fwrite($file,date('c') . ": $str\n"); fclose($file); } try{ if(is_uploaded_file($_FILES['tfile']['tmp_name'])){ debug("step 1: the file was uploaded"); $norg=date('y-m-d')."_".md5(microtime()); $nfle="testfiles/$norg.xml"; $ndir="testfiles/$norg"; $ndir2="testfiles/$norg"; if(move_uploaded_file($_FILES['tfile']['tmp_name'],"$nfle")){ debug("step 2: the file was moved to the directory"); debug("memory_get_usage(): " . memory_get_usage()); debug("memory_get_usage(true): " . memory_get_usage(true)); debug("memory_get_peak_usage(): " . memory_get_peak_usage()); debug("memory_get_peak_usage(true): " . memory_get_peak_usage(true)); $shll=shell_exec("./crm_cutfile_v2.sh \"$nfle\" \"$ndir\" \"$norg\" "); debug("result: $shll"); debug("memory_get_usage(): " . memory_get_usage()); debug("memory_get_usage(true): " . memory_get_usage(true)); debug("memory_get_peak_usage(): " . memory_get_peak_usage()); debug("memory_get_peak_usage(true): " . memory_get_peak_usage(true)); debug("step 3: the file was cutted. END"); } else{ debug("ERROR: I didnt move the file"); exit(); } } else{ debug("ERROR: I didnt upload the file"); //exit(); } } catch(Exception $e){ debug("Exception: " . $e-getMessage()); exit(); } ? Test function uploadFile(){ alert("start"); if(document.test.tfile.value==""){ alert("First you have to upload a file"); } else{ document.test.submit(); } } Bash script with AWK #!/bin/bash #For single messages (one message per contact) function cutfile(){ lines=$( cat "$1" | awk 'END {print NR}' ) fline="$4"; if [ -d "$2" ]; then exsts=1 else mkdir "$2" fi cp "$1" "$2/datasource.xml" cd "$2" i=1 contfile=1 while [ $i -le $lines ] do currentline=$( cat "datasource.xml" | awk -v fl=$i 'NR==fl {print $0}' ) #creates first file if [ $i -eq 1 ]; then echo "$fline" "$3_1.txt" else #creates the rest of files when there are more than 10,000 contacts rsd=$(( ( $i - 2 ) % 10000 )) if [ $rsd -eq 0 ]; then echo "" "$3_$contfile.txt" contfile=$(( $contfile + 1 )) echo "$fline" "$3_$contfile.txt" fi fi echo "$currentline" "$3_$contfile.txt" i=$(( $i + 1 )) done echo "" "$3_$contfile.txt" return 1 } #For multiple messages (one message for all contacts) function cutfile_multi(){ return 1 } cutfile "$1" "$2" "$3" "$4" echo 1 thanks!!!!! =D

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• How to break a Hibernate session?

  - by Péter Török

  In the Hibernate reference, it is stated several times that All exceptions thrown by Hibernate are fatal. This means you have to roll back the database transaction and close the current Session. You aren’t allowed to continue working with a Session that threw an exception. One of our legacy apps uses a single session to update/insert many records from files into a DB table. Each recourd update/insert is done in a separate transaction, which is then duly committed (or rolled back in case an error occurred). Then for the next record a new transaction is opened etc. But the same session is used throughout the whole process, even if a HibernateException was caught in the middle. We are using Oracle 9i btw with Hibernate 3.24.sp1 on JBoss 4.2. Reading the above in the book, I realized that this design may fail. So I refactored the app to use a separate session for each record update. In a unit test with a mock session factory, I could prove that it is now requesting a new session for each record update. So far, so good. However, we found no way to reproduce the session failure while testing the whole app (would this be a stress test btw, or ...?). We thought of shutting down the listener of the DB but we realized that the app is keeping a bunch of connections open to the DB, and the listener would not affect those connections. (This is a web app, activated once every night by a scheduler, but it can also be activated via the browser.) Then we tried to kill some of those connections in the DB while the app was processing updates - this resulted in some failed updates, but then the app happily continued. Apparently Hibernate is clever enough to reopen broken connections under the hood without breaking the whole session. So this might not be a critical issue, as our app seems to be robust enough even in its original form. However, the issue keeps bugging me. I would like to know: Under what circumstances does the Hibernate session really become unusable after a HibernateException was thrown? How to reproduce this in a test? (What's the proper term for such a test?)

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• Two UIViews, one UIViewController (in one UINavigationController)

  - by jdandrea

  Given an iPhone app with a UITableViewController pushed onto a UINavigationController, I would like to add a right bar button item to toggle between the table view and an "alternate" view of the same data. Let's also say that this other view uses the same data but is not a UITableView. Now, I know variations on this question already exist on Stack Overflow. However, in this case, that alternate view would not be pushed onto the UINavigationController. It would be visually akin to flipping the current UIViewController's table view over and revealing the other view, then being able to flip back. In other words, it's intended to take up a single spot in the UINavigationController hierarchy. Moreover, whatever selection you ultimately make from within either view will push a common UIViewController onto the UINavigationController stack. Still more info: We don't want to use a separate UINavigationController just to handle this pair of views, and we don't want to split these apart via a UITabBarController either. Visually and contextually, the UX is meant to show two sides of the same coin. It's just that those two sides happen to involve their own View Controllers in normal practice. Now … it turns out I have already gone and quickly set this up to see how it might work! However, upon stepping back to examine it, I get the distinct impression that I went about it in a rather non-MVC way, which of course concerns me a bit. Here's what I did at a high level. Right now, I have a UIViewController (not a UITableViewController) that handles all commonalities between the two views, such as fetching the raw data. I also have two NIBs, one for each view, and two UIView objects to go along with them. (One of them is a UITableView, which is a kind of UIView.) I switch between the views using animation (easy enough). Also, in an effort to keep things encapsulated, the now-split-apart UITableView (not the UIViewController!) acts as its own delegate and data source, fetching data from the VC. The VC is set up as a weak, non-retained object in the table view. In parallel, the alternate view gets at the raw data from the VC in the exact same way. So, there are a few things that smell funny here. The weak linking from child to parent, while polite, seems like it might be wrong. Making a UITableView the table's data source and delegate also seems odd to me, thinking that a view controller is where you want to put that per Apple's MVC diagrams. As it stands now, it would appear as if the view knows about the model, which isn't good. Loading up both views in advance also seems odd, because lazy loading is no longer in effect. Losing the benefits of a UITableViewController (like auto-scrolling to cells with text fields) is also a bit frustrating, and I'd rather not reinvent the wheel to work around that as well. Given all of the above, and given we want that "flip effect" in the context of a single spot on a single UINavigationController, and given that both views are two sides of the same coin, is there a better, more obvious way to design this that I'm just happening to miss completely? Clues appreciated!

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• Build path issues learning Guice

  - by Preston

  I can't figure out why I'm getting this error below I have included all the appropriate jars as far as I can tell(I have included eclipses .classpath file below.) All of the classpath entries resolve just fine. What am I missing? The type javax.servlet.ServletContextListener cannot be resolved. It is indirectly referenced from required .class files on the "extends GuiceServletContextListener" line - import com.google.inject.Guice; import com.google.inject.Injector; import com.google.inject.servlet.GuiceServletContextListener; import com.google.inject.servlet.ServletModule; public class ServletConfig extends GuiceServletContextListener { @Override protected Injector getInjector() { return Guice.createInjector(new ServletModule(){ @Override protected void configureServlets() { // TODO: add necessary code to bind } }); } } .Classpath <?xml version="1.0" encoding="UTF-8"?> <classpath> <classpathentry kind="src" path="src"/> <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/jdk1.7.0_21"> <attributes> <attribute name="owner.project.facets" value="java"/> </attributes> </classpathentry> <classpathentry kind="con" path="oracle.eclipse.tools.glassfish.lib.system"> <attributes> <attribute name="owner.project.facets" value="jst.web"/> </attributes> </classpathentry> <classpathentry kind="con" path="org.eclipse.jst.j2ee.internal.web.container"/> <classpathentry kind="con" path="org.eclipse.jst.j2ee.internal.module.container"/> <classpathentry kind="lib" path="guice-3.0/aopalliance.jar"/> <classpathentry kind="lib" path="guice-3.0/guice-3.0.jar"/> <classpathentry kind="lib" path="guice-3.0/guice-servlet-3.0.jar"/> <classpathentry kind="lib" path="guice-3.0/javax.inject.jar"/> <classpathentry kind="output" path="build/classes"/> </classpath>

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• Weighted round robins via TTL - possible?

  - by Joe Hopfgartner

  I currently use DNS round robin for load balancing, which works great. The records look like this (I have a ttl of 120 seconds) ;; ANSWER SECTION: orion.2x.to. 116 IN A 80.237.201.41 orion.2x.to. 116 IN A 87.230.54.12 orion.2x.to. 116 IN A 87.230.100.10 orion.2x.to. 116 IN A 87.230.51.65 I learned that not every ISP / device treats such a response the same way. For example some DNS servers rotate the addresses randomly or always cycle them through. Some just propagate the first entry, others try to determine which is best (regionally near) by looking at the ip address. However if the userbase is big enough (spreads over multiple ISPs etc) it balances pretty well. The discrepancies from highest to lowest loaded server hardly every exceeds 15%. However now I have the problem that I am introducing more servers into the systems, that not all have the same capacities. I currently only have 1gbps servers, but I want to work with 100mbit and also 10gbps servers too. So what I want is I want to introduce a server with 10 GBps with a weight of 100, a 1 gbps server with a weight of 10 and a 100 mbit server with a weight of 1. I used to add servers twice to bring more traffic to them (which worked nice. the bandwidth doubled almost.) But adding a 10gbit server 100 times to DNS is a bit rediculous. So I thought about using the TTL. If I give server A 240 seconds ttl and server B only 120 seconds (which is about about the minimum to use for round robin, as a lot of dns servers set to 120 if a lower ttl is specified.. so i have heard) I think something like this should occour in an ideal scenario: first 120 seconds 50% of requests get server A -> keep it for 240 seconds. 50% of requests get server B -> keep it for 120 seconds second 120 seconds 50% of requests still have server A cached -> keep it for another 120 seconds. 25% of requests get server A -> keep it for 240 seconds 25% of requests get server B -> keep it for 120 seconds third 120 seconds 25% will get server A (from the 50% of Server A that now expired) -> cache 240 sec 25% will get server B (from the 50% of Server A that now expired) -> cache 120 sec 25% will have server A cached for another 120 seconds 12.5% will get server B (from the 25% of server B that now expired) -> cache 120sec 12.5% will get server A (from the 25% of server B that now expired) -> cache 240 sec fourth 120 seconds 25% will have server A cached -> cache for another 120 secs 12.5% will get server A (from the 25% of b that now expired) -> cache 240 secs 12.5% will get server B (from the 25% of b that now expired) -> cache 120 secs 12.5% will get server A (from the 25% of a that now expired) -> cache 240 secs 12.5% will get server B (from the 25% of a that now expired) -> cache 120 secs 6.25% will get server A (from the 12.5% of b that now expired) -> cache 240 secs 6.25% will get server B (from the 12.5% of b that now expired) -> cache 120 secs 12.5% will have server A cached -> cache another 120 secs ... i think i lost something at this point but i think you get the idea.... As you can see this gets pretty complicated to predict and it will for sure not work out like this in practice. But it should definitely have an effect on the distribution! I know that weighted round robin exists and is just controlled by the root server. It just cycles through dns records when responding and returns dns records with a set propability that corresponds to the weighting. My DNS server does not support this, and my requirements are not that precise. If it doesnt weight perfectly its okay, but it should go into the right direction. I think using the TTL field could be a more elegant and easier solution - and it deosnt require a dns server that controls this dynamically, which saves resources - which is in my opinion the whole point of dns load balancing vs hardware load balancers. My question now is... are there any best prectices / methos / rules of thumb to weight round robin distribution using the TTL attribute of DNS records? Edit: The system is a forward proxy server system. The amount of Bandwidth (not requests) exceeds what one single server with ethernet can handle. So I need a balancing solution that distributes the bandwidth to several servers. Are there any alternative methods than using DNS? Of course I can use a load balancer with fibre channel etc, but the costs are rediciulous and it also increases only the width of the bottleneck and does not eliminate it. The only thing i can think of are anycast (is it anycast or multicast?) ip addresses, but I don't have the means to set up such a system.

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• What are the benefits of using ORM over XML Serialization/Deserialization?

  - by Tequila Jinx

  I've been reading about NHibernate and Microsoft's Entity Framework to perform Object Relational Mapping against my data access layer. I'm interested in the benefits of having an established framework to perform ORM, but I'm curious as to the performance costs of using it against standard XML Serialization and Deserialization. Right now, I develop stored procedures in Oracle and SQL Server that use XML Types for either input or output parameters and return or shred XML depending on need. I use a custom database command object that uses generics to deserialize the XML results into a specified serializable class. By using a combination of generics, xml (de)serialization and Microsoft's DAAB, I've got a process that's fairly simple to develop against regardless of the data source. Moreover, since I exclusively use Stored Procedures to perform database operations, I'm mostly protected from changes in the data structure. Here's an over-simplified example of what I've been doing. static void main() { testXmlClass test = new test(1); test.Name = "Foo"; test.Save(); } // Example Serializable Class ------------------------------------------------ [XmlRootAttribute("test")] class testXmlClass() { [XmlElement(Name="id")] public int ID {set; get;} [XmlElement(Name="name")] public string Name {set; get;} //create an instance of the class loaded with data. public testXmlClass(int id) { GenericDBProvider db = new GenericDBProvider(); this = db.ExecuteSerializable("myGetByIDProcedure"); } //save the class to the database... public Save() { GenericDBProvider db = new GenericDBProvider(); db.AddInParameter("myInputParameter", DbType.XML, this); db.ExecuteSerializableNonQuery("mySaveProcedure"); } } // Database Handler ---------------------------------------------------------- class GenericDBProvider { public T ExecuteSerializable<T>(string commandText) where T : class { XmlSerializer xml = new XmlSerializer(typeof(T)); // connection and command code is assumed for the purposes of this example. // the final results basically just come down to... return xml.Deserialize(commandResults) as T; } public void ExecuteSerializableNonQuery(string commandText) { // once again, connection and command code is assumed... // basically, just execute the command along with the specified // parameters which have been serialized. } public void AddInParameter(string name, DbType type, object value) { StringWriter w = new StringWriter(); XmlSerializer x = new XmlSerializer(value.GetType()); //handle serialization for serializable classes. if (type == DbType.Xml && (value.GetType() != typeof(System.String))) { x.Serialize(w, value); w.Close(); // store serialized object in a DbParameterCollection accessible // to my other methods. } else { //handle all other parameter types } } } I'm starting a new project which will rely heavily on database operations. I'm very curious to know whether my current practices will be sustainable in a high-traffic situation and whether or not I should consider switching to NHibernate or Microsoft's Entity Framework to perform what essentially seems to boil down to the same thing I'm currently doing. I appreciate any advice you may have.

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• Complex relationship between tables in NHibernate

  - by Ilya Kogan

  Hi all, I'm writing a Fluent NHibernate mapping for a legacy Oracle database. The challenge is that the tables have composite primary keys. If I were at total freedom, I would redesign the relationships and auto-generate primary keys, but other applications must write to the same database and read from it, so I cannot do it. These are the two tables I'll focus on: Example data Trips table: 1, 10:00, 11:00 ... 1, 12:00, 15:00 ... 1, 16:00, 19:00 ... 2, 12:00, 13:00 ... 3, 9:00, 18:00 ... Faults table: 1, 13:00 ... 1, 23:00 ... 2, 12:30 ... In this case, vehicle 1 made three trips and has two faults. The first fault happened during the second trip, and the second fault happened while the vehicle was resting. Vehicle 2 had one trip, during which a fault happened. Constraints Trips of the same vehicle never overlap. So the tables have an optional one-to-many relationship, because every fault either happens during a trip or it doesn't. If I wanted to join them in SQL, I would write: select ... from Faults left outer join Trips on Faults.VehicleId = Trips.VehicleId and Faults.FaultTime between Trips.TripStartTime and Trips.TripEndTime and then I'd get a dataset where every fault appears exactly once (one-to-many as I said). Note that there is no Vehicles table, and I don't need one. But I did create a view that contains all VehicleIds from both tables, so I can use it as a junction table. What am I actually looking for? The tables are huge because they cover years of data, and every time I only need to fetch a range of a few hours. So I need a mapping and a criteria that will run something like the following SQL underneath: select ... from Faults left outer join Trips on Faults.VehicleId = Trips.VehicleId and Faults.FaultTime between Trips.TripStartTime and Trips.TripEndTime where Faults.FaultTime between :p0 and :p1 Do you have any ideas how to achieve it? Note 1: Currently the application shouldn't write to the database, so persistence is not a must, although if the mapping supports persistence, it may help at some point in the future. Note 2: I know it's a tough one, so if you give me a great answer, you will be properly rewarded :) Thank you for reading this long question, and now I only hope for the best :)

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• Best Practices / Patterns for Enterprise Protection/Remediation of SSNs (Social Security Numbers)

  - by Erik Neu

  I am interested in hearing about enterprise solutions for SSN handling. (I looked pretty hard for any pre-existing post on SO, including reviewing the terriffic SO automated "Related Questions" list, and did not find anything, so hopefully this is not a repeat.) First, I think it is important to enumerate the reasons systems/databases use SSNs: (note—these are reasons for de facto current state—I understand that many of them are not good reasons) Required for Interaction with External Entities. This is the most valid case—where external entities your system interfaces with require an SSN. This would typically be government, tax and financial. SSN is used to ensure system-wide uniqueness. SSN has become the default foreign key used internally within the enterprise, to perform cross-system joins. SSN is used for user authentication (e.g., log-on) The enterprise solution that seems optimum to me is to create a single SSN repository that is accessed by all applications needing to look up SSN info. This repository substitutes a globally unique, random 9-digit number (ASN) for the true SSN. I see many benefits to this approach. First of all, it is obviously highly backwards-compatible—all your systems "just" have to go through a major, synchronized, one-time data-cleansing exercise, where they replace the real SSN with the alternate ASN. Also, it is centralized, so it minimizes the scope for inspection and compliance. (Obviously, as a negative, it also creates a single point of failure.) This approach would solve issues 2 and 3, without ever requiring lookups to get the real SSN. For issue #1, authorized systems could provide an ASN, and be returned the real SSN. This would of course be done over secure connections, and the requesting systems would never persist the full SSN. Also, if the requesting system only needs the last 4 digits of the SSN, then that is all that would ever be passed. Issue #4 could be handled the same way as issue #1, though obviously the best thing would be to move away from having users supply an SSN for log-on. There are a couple of papers on this: UC Berkely: http://bit.ly/bdZPjQ Oracle Vault: bit.ly/cikbi1

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• Use QuickCheck by generating primes

  - by Dan

  Background For fun, I'm trying to write a property for quick-check that can test the basic idea behind cryptography with RSA. Choose two distinct primes, p and q. Let N = p*q e is some number relatively prime to (p-1)(q-1) (in practice, e is usually 3 for fast encoding) d is the modular inverse of e modulo (p-1)(q-1) For all x such that 1 < x < N, it is always true that (x^e)^d = x modulo N In other words, x is the "message", raising it to the eth power mod N is the act of "encoding" the message, and raising the encoded message to the dth power mod N is the act of "decoding" it. (The property is also trivially true for x = 1, a case which is its own encryption) Code Here are the methods I have coded up so far: import Test.QuickCheck -- modular exponentiation modExp :: Integral a => a -> a -> a -> a modExp y z n = modExp' (y `mod` n) z `mod` n where modExp' y z | z == 0 = 1 | even z = modExp (y*y) (z `div` 2) n | odd z = (modExp (y*y) (z `div` 2) n) * y -- relatively prime rPrime :: Integral a => a -> a -> Bool rPrime a b = gcd a b == 1 -- multiplicative inverse (modular) mInverse :: Integral a => a -> a -> a mInverse 1 _ = 1 mInverse x y = (n * y + 1) `div` x where n = x - mInverse (y `mod` x) x -- just a quick way to test for primality n `divides` x = x `mod` n == 0 primes = 2:filter isPrime [3..] isPrime x = null . filter (`divides` x) $ takeWhile (\y -> y*y <= x) primes -- the property prop_rsa (p,q,x) = isPrime p && isPrime q && p /= q && x > 1 && x < n && rPrime e t ==> x == (x `powModN` e) `powModN` d where e = 3 n = p*q t = (p-1)*(q-1) d = mInverse e t a `powModN` b = modExp a b n (Thanks, google and random blog, for the implementation of modular multiplicative inverse) Question The problem should be obvious: there are way too many conditions on the property to make it at all usable. Trying to invoke quickCheck prop_rsa in ghci made my terminal hang. So I've poked around the QuickCheck manual a bit, and it says: Properties may take the form forAll <generator> $ \<pattern> -> <property> How do I make a <generator> for prime numbers? Or with the other constraints, so that quickCheck doesn't have to sift through a bunch of failed conditions? Any other general advice (especially regarding QuickCheck) is welcome.

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• is it right to call ejb bean from thread by ThreadPoolExecutor?

  - by kislo_metal

  I trying to call some ejb bean method from tread. and getting error : (as is glassfish v3) Log Level SEVERE Logger javax.enterprise.system.std.com.sun.enterprise.v3.services.impl Name-Value Pairs {_ThreadName=Thread-1, _ThreadID=42} Record Number 928 Message ID java.lang.NullPointerException at ua.co.rufous.server.broker.TempLicService.run(TempLicService.java Complete Message 35) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:637) here is tread public class TempLicService implements Runnable { String hash; //it`s Stateful bean @EJB private LicActivatorLocal lActivator; public TempLicService(String hash) { this.hash= hash; } @Override public void run() { lActivator.proccessActivation(hash); } } my ThreadPoolExecutor public class RequestThreadPoolExecutor extends ThreadPoolExecutor { private boolean isPaused; private ReentrantLock pauseLock = new ReentrantLock(); private Condition unpaused = pauseLock.newCondition(); private static RequestThreadPoolExecutor threadPool; private RequestThreadPoolExecutor() { super(1, Integer.MAX_VALUE, 10, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); System.out.println("RequestThreadPoolExecutor created"); } public static RequestThreadPoolExecutor getInstance() { if (threadPool == null) threadPool = new RequestThreadPoolExecutor(); return threadPool; } public void runService(Runnable task) { threadPool.execute(task); } protected void beforeExecute(Thread t, Runnable r) { super.beforeExecute(t, r); pauseLock.lock(); try { while (isPaused) unpaused.await(); } catch (InterruptedException ie) { t.interrupt(); } finally { pauseLock.unlock(); } } public void pause() { pauseLock.lock(); try { isPaused = true; } finally { pauseLock.unlock(); } } public void resume() { pauseLock.lock(); try { isPaused = false; unpaused.signalAll(); } finally { pauseLock.unlock(); } } public void shutDown() { threadPool.shutdown(); } //<<<<<< creating thread here public void runByHash(String hash) { Runnable service = new TempLicService(hash); threadPool.runService(service); } } and method where i call it (it is gwt servlet, but there is no proble to call thread that not contain ejb) : @Override public Boolean submitHash(String hash) { System.out.println("submiting hash"); try { if (tBoxService.getTempLicStatus(hash) == 1) { //<<< here is the call RequestThreadPoolExecutor.getInstance().runByHash(hash); return true; } } catch (NoResultException e) { e.printStackTrace(); } return false; } I need to organize some pool of submitting hash to server (calls of LicActivator bean), is ThreadPoolExecutor design good idea and why it is not working in my case? (as I know we can`t create thread inside bean, but could we call bean from different threads? ). If No, what is the bast practice for organize such request pool? Thanks. << Answer: I am using DI (EJB 3.1) soo i do not need any look up here. (application packed in ear and both modules in it (web module and ejb), it works perfect for me). But I can use it only in managed classes. So.. 2.Can I use manual look up in Tread ? Could I use Bean that extends ThreadPoolExecutor and calling another bean that implements Runnable ? Or it is not allowed ?

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• Log a user in to an ASP.net application using Windows Authentication without using Windows Authentic

  - by Rising Star

  I have an ASP.net application I'm developing authentication for. I am using an existing cookie-based log on system to log users in to the system. The application runs as an anonymous account and then checks the cookie when the user wants to do something restricted. This is working fine. However, there is one caveat: I've been told that for each page that connects to our SQL server, I need to make it so that the user connects using an Active Directory account. because the system I'm using is cookie based, the user isn't logged in to Active Directory. Therefore, I use impersonation to connect to the server as a specific account. However, the powers that be here don't like impersonation; they say that it clutters up the code. I agree, but I've found no way around this. It seems that the only way that a user can be logged in to an ASP.net application is by either connecting with Internet Explorer from a machine where the user is logged in with their Active Directory account or by typing an Active Directory username and password. Neither of these two are workable in my application. I think it would be nice if I could make it so that when a user logs in and receives the cookie (which actually comes from a separate log on application, by the way), there could be some code run which tells the application to perform all network operations as the user's Active Directory account, just as if they had typed an Active Directory username and password. It seems like this ought to be possible somehow, but the solution evades me. How can I make this work? Update To those who have responded so far, I apologize for the confusion I have caused. The responses I've received indicate that you've misunderstood the question, so please allow me to clarify. I have no control over the requirement that users must perform network operations (such as SQL queries) using Active Directory accounts. I've been told several times (online and in meat-space) that this is an unusual requirement and possibly bad practice. I also have no control over the requirement that users must log in using the existing cookie-based log on application. I understand that in an ideal MS ecosystem, I would simply dis-allow anonymous access in my IIS settings and users would log in using Windows Authentication. This is not the case. The current system is that as far as IIS is concerned, the user logs in anonymously (even though they supply credentials which result in the issuance of a cookie) and we must programmatically check the cookie to see if the user has access to any restricted resources. In times past, we have simply used a single SQL account to perform all queries. My direct supervisor (who has many years of experience with this sort of thing) wants to change this. He says that if each user has his own AD account to perform SQL queries, it gives us more of a trail to follow if someone tries to do something wrong. The closest thing I've managed to come up with is using WIF to give the user a claim to a specific Active Directory account, but I still have to use impersonation because even still, the ASP.net process presents anonymous credentials to the SQL server. It boils down to this: Can I log users in with Active Directory accounts in my ASP.net application without having the users manually enter their AD credentials? (Windows Authentication)

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• PostgreSQL - fetch the row which has the Max value for a column

  - by Joshua Berry

  I'm dealing with a Postgres table (called "lives") that contains records with columns for time_stamp, usr_id, transaction_id, and lives_remaining. I need a query that will give me the most recent lives_remaining total for each usr_id There are multiple users (distinct usr_id's) time_stamp is not a unique identifier: sometimes user events (one by row in the table) will occur with the same time_stamp. trans_id is unique only for very small time ranges: over time it repeats remaining_lives (for a given user) can both increase and decrease over time example: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 07:00 | 1 | 1 | 1 09:00 | 4 | 2 | 2 10:00 | 2 | 3 | 3 10:00 | 1 | 2 | 4 11:00 | 4 | 1 | 5 11:00 | 3 | 1 | 6 13:00 | 3 | 3 | 1 As I will need to access other columns of the row with the latest data for each given usr_id, I need a query that gives a result like this: time_stamp|lives_remaining|usr_id|trans_id ----------------------------------------- 11:00 | 3 | 1 | 6 10:00 | 1 | 2 | 4 13:00 | 3 | 3 | 1 As mentioned, each usr_id can gain or lose lives, and sometimes these timestamped events occur so close together that they have the same timestamp! Therefore this query won't work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp) AS max_timestamp FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp = b.time_stamp Instead, I need to use both time_stamp (first) and trans_id (second) to identify the correct row. I also then need to pass that information from the subquery to the main query that will provide the data for the other columns of the appropriate rows. This is the hacked up query that I've gotten to work: SELECT b.time_stamp,b.lives_remaining,b.usr_id,b.trans_id FROM (SELECT usr_id, max(time_stamp || '*' || trans_id) AS max_timestamp_transid FROM lives GROUP BY usr_id ORDER BY usr_id) a JOIN lives b ON a.max_timestamp_transid = b.time_stamp || '*' || b.trans_id ORDER BY b.usr_id Okay, so this works, but I don't like it. It requires a query within a query, a self join, and it seems to me that it could be much simpler by grabbing the row that MAX found to have the largest timestamp and trans_id. The table "lives" has tens of millions of rows to parse, so I'd like this query to be as fast and efficient as possible. I'm new to RDBM and Postgres in particular, so I know that I need to make effective use of the proper indexes. I'm a bit lost on how to optimize. I found a similar discussion here. Can I perform some type of Postgres equivalent to an Oracle analytic function? Any advice on accessing related column information used by an aggregate function (like MAX), creating indexes, and creating better queries would be much appreciated! P.S. You can use the following to create my example case: create TABLE lives (time_stamp timestamp, lives_remaining integer, usr_id integer, trans_id integer); insert into lives values ('2000-01-01 07:00', 1, 1, 1); insert into lives values ('2000-01-01 09:00', 4, 2, 2); insert into lives values ('2000-01-01 10:00', 2, 3, 3); insert into lives values ('2000-01-01 10:00', 1, 2, 4); insert into lives values ('2000-01-01 11:00', 4, 1, 5); insert into lives values ('2000-01-01 11:00', 3, 1, 6); insert into lives values ('2000-01-01 13:00', 3, 3, 1);

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• Help with this code.

  - by karthick6891

  Heading ##Hey guys i need help with this code.The short version is,i have to do match the follwing by using drag and drop in jquery and later i need to show a message whether it is right or wrong. var output = "Wrong"; var old_item ; var new_item ; var newObjArray=[]; $(function() { var $gallery = $('.gallery'), $trash = $('.trash'); $('div',$gallery).draggable({ revert: 'invalid', containment: 'document', helper: 'clone', cursor: 'move', }); // let the trash be droppable, accepting the gallery items $trash.droppable({ //accept: '#gallery div', //activeClass: 'ui-state-highlight', tolerance: 'touch', drop: function(ev, ui) { new_item = ui.draggable; $(this).droppable("option","activeClass",'.ui-state-highlight'); if(contains(newObjArray,ui.draggable)) { newObjArray.pop(ui.draggable); } newObjArray.push(ui.draggable); deleteImage(ui.draggable,$(this)); } }); // let the gallery be droppable as well, accepting items from the trash $gallery.droppable({ //accept: '#trash li', activeClass: 'custom-state-active', drop: function(ev, ui) { recycleImage(ui.draggable); } }); // image deletion function function deleteImage($item,element) { var $list; $item.fadeOut(10,function() { if($(".ui-widget-content", element).length <1){ old_item = $item; $list = $('<div class="gallery ui-helper-reset"/>').appendTo(element); //$('ul',$trash).length ? $('ul',$trash) : $('<ul class="gallery ui-helper-reset"/>').appendTo($trash); $item.appendTo($list).fadeIn(10); } else{ recycleImage($(".ui-widget-content",element)); $list = $('<div class="gallery ui-helper-reset"/>').appendTo(element); $item.appendTo($list).fadeIn(10); old_item = $item; } }); } //check for given answer // image recycle function function recycleImage($item) { $item.fadeOut(10,function() { $item.find("img").end().appendTo($gallery).fadeIn(10); }); } // image preview function, demonstrating the ui.dialog used as a modal window }); function checkOrder(){ if(newObjArray==null){ } else if(newObjArray!=null){ if(newObjArray[0].attr("id")=="5"&& newObjArray[1].attr("id")=="1" && newObjArray[2].attr("id")=="3" && newObjArray[3].attr("id")=="2" && newObjArray[4].attr("id")=="4"){ parent.parent.increaseCorrectA(); } else{ parent.parent.increaseWrongA(); } } } function contains(a, obj) { var i = a.length; while (i--) { if (a[i] === obj) { return true; } } return false; } I am calling the function checkOrder() from the html page after the matching of items is over.What happens here is i have just stored the user responses on the draggable over droppable in an array,based on it's position.It is a bad practice cause,i am saying whether it's right or wrong through its position in the array.The only thing i can do is get the draggable's id present in the droppable.But i dont know how to get that inside the function checkOrder().Any ideas please?

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• Dynamic data-entry value store

  - by simendsjo

  I'm creating a data-entry application where users are allowed to create the entry schema. My first version of this just created a single table per entry schema with each entry spanning a single or multiple columns (for complex types) with the appropriate data type. This allowed for "fast" querying (on small datasets as I didn't index all columns) and simple synchronization where the data-entry was distributed on several databases. I'm not quite happy with this solution though; the only positive thing is the simplicity... I can only store a fixed number of columns. I need to create indexes on all columns. I need to recreate the table on schema changes. Some of my key design criterias are: Very fast querying (Using a simple domain specific query language) Writes doesn't have to be fast Many concurrent users Schemas will change often Schemas might contain many thousand columns The data-entries might be distributed and needs syncronization. Preferable MySQL and SQLite - Databases like DB2 and Oracle is out of the question. Using .Net/Mono I've been thinking of a couple of possible designs, but none of them seems like a good choice. Solution 1: Union like table containing a Type column and one nullable column per type. This avoids joins, but will definitly use a lot of space. Solution 2: Key/value store. All values are stored as string and converted when needed. Also use a lot of space, and of course, I hate having to convert everything to string. Solution 3: Use an xml database or store values as xml. Without any experience I would think this is quite slow (at least for the relational model unless there is some very good xpath support). I also would like to avoid an xml database as other parts of the application fits better as a relational model, and being able to join the data is helpful. I cannot help to think that someone has solved (some of) this already, but I'm unable to find anything. Not quite sure what to search for either... I know market research is doing something like this for their questionnaires, but there are few open source implementations, and the ones I've found doesn't quite fit the bill. PSPP has much of the logic I'm thinking of; primitive column types, many columns, many rows, fast querying and merging. Too bad it doesn't work against a database.. And of course... I don't need 99% of the provided functionality, but a lot of stuff not included. I'm not sure this is the right place to ask such a design related question, but I hope someone here has some tips, know of any existing work, or can point me to a better place to ask such a question. Thanks in advance!

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• HttpClient multithread performance

  - by pepper

  I have an application which downloads more than 4500 html pages from 62 target hosts using HttpClient (4.1.3 or 4.2-beta). It runs on Windows 7 64-bit. Processor - Core i7 2600K. Network bandwidth - 54 Mb/s. At this moment it uses such parameters: DefaultHttpClient and PoolingClientConnectionManager; Also it hasIdleConnectionMonitorThread from http://hc.apache.org/httpcomponents-client-ga/tutorial/html/connmgmt.html; Maximum total connections = 80; Default maximum connections per route = 5; For thread management it uses ForkJoinPool with the parallelism level = 5 (Do I understand correctly that it is a number of working threads?) In this case my network usage (in Windows task manager) does not rise above 2.5%. To download 4500 pages it takes 70 minutes. And in HttpClient logs I have such things: DEBUG ForkJoinPool-2-worker-1 [org.apache.http.impl.conn.PoolingClientConnectionManager]: Connection released: [id: 209][route: {}-http://stackoverflow.com][total kept alive: 6; route allocated: 1 of 5; total allocated: 10 of 80] Total allocated connections do not raise above 10-12, in spite of that I've set it up to 80 connections. If I'll try to rise parallelism level to 20 or 80, network usage remains the same but a lot connection time-outs will be generated. I've read tutorials on hc.apache.org (HttpClient Performance Optimization Guide and HttpClient Threading Guide) but they does not help. Task's code looks like this: public class ContentDownloader extends RecursiveAction { private final HttpClient httpClient; private final HttpContext context; private List<Entry> entries; public ContentDownloader(HttpClient httpClient, List<Entry> entries){ this.httpClient = httpClient; context = new BasicHttpContext(); this.entries = entries; } private void computeDirectly(Entry entry){ final HttpGet get = new HttpGet(entry.getLink()); try { HttpResponse response = httpClient.execute(get, context); int statusCode = response.getStatusLine().getStatusCode(); if ( (statusCode >= 400) && (statusCode <= 600) ) { logger.error("Couldn't get content from " + get.getURI().toString() + "\n" + response.toString()); } else { HttpEntity entity = response.getEntity(); if (entity != null) { String htmlContent = EntityUtils.toString(entity).trim(); entry.setHtml(htmlContent); EntityUtils.consumeQuietly(entity); } } } catch (Exception e) { } finally { get.releaseConnection(); } } @Override protected void compute() { if (entries.size() <= 1){ computeDirectly(entries.get(0)); return; } int split = entries.size() / 2; invokeAll(new ContentDownloader(httpClient, entries.subList(0, split)), new ContentDownloader(httpClient, entries.subList(split, entries.size()))); } } And the question is - what is the best practice to use multi threaded HttpClient, may be there is a some rules for setting up ConnectionManager and HttpClient? How can I use all of 80 connections and raise network usage? If necessary, I will provide more code.

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• Where do I start ?

  - by Panthe

  Brief History: Just graduated high school, learned a bit of python and C++, have no friends with any helpful computer knowledge at all. Out of anyone i met in my school years I was probably the biggest nerd, but no one really knew. I consider my self to have a vast amount of knowledge on computers and tech then the average person. built/fixed tons of computers, and ability to troubleshoot pretty much any problem I came across. Now that high school is over, Ive really been thinking about my career. Loving, living computers for the past 15 years of my life I decided to take my ability's and try to learn computer programming, why I didn't start earlier I don't know, seems to be big mistake on my part... Doing some research I concluded that Python was the first programming language I should learn, since it was high level and easier to understand then C++ and Java. I also knew that to become good at what I did I needed to know more then just 2 or 3 languages, which didn't seem like a big problem considering once I learned the way Python worked, mainly syntax changed, and the rest would come naturally. I watched a couple of youtube videos, downloaded some book pdf's and snooped around from some tutorials here and there to get the hang of what to do. A two solid weeks had passed of trying to understand the syntax, create small programs that used the basic functions and understanding how it worked, I think i have got the hang of it. It breaks down into what ive been dealing with all this time (although i kinda knew) is that, input,output, loops, functions and other things derived from 0's and 1's storing data and recalling it, ect. (A VERY BASIC IDEA). Ive been able to create small programs, Hangman, file storing, temperature conversion, Caeser Cipher decode/encoding, Fibonacci Sequence and more, which i can create and understand how each work. Being 2 weeks into this, I have learned alot. Nothing at all compared to what i should be learning in the years to come if i get a grip on what I'm doing. While doing these programs I wont stop untill I've done doing a practice problem on a book, which embarresing enough will take me a couple hour depending on the complexity of it. I absolutly will not put aside the challenge until its complete, WHICH CAN BE EXTREMELY DRAINING, ive tried most problems without cheating and reached success, which makes me feel extremely proud of my self after completing something after much trial and error. After all this I have met the demon, alogrithm's which seem to be key to effiecent code. I cant seem to rap my head around some of the computer codes people put out there using numbers, and sometimes even basic functions, I have been able to understand them after a while but i know there are alot more complex things to come, considering my self smart, functions that require complex codes, actually hurt my brain. NOTHING EVER IN LIFE HURT MY BRAIN....... not even math classes in highschool, trying to understand some of the stuff people put out there makes me feel like i have a mental disadvantage lol... i still walk forward though, crossing my fingers that the understanding will come with time. Sorry if is this is long i just wish someone takes all these things into consideration when answering my question. even through all these downsides im still pushing through and continuing to try and get good at this, i know reading these tutorials wont make me any good unless i can become creative and make my own, understand other peoples programs, so this leads me to the simple question i could have asked in the beginning..... WHERE IN THE WORLD DO I START ? Ive been trying to find out how to understand some of the open source projects, how i can work with experianced coders to learn from them and help them, but i dont think thats even possible by the way how far people's knowledge is compared to me, i have no freinds who i can learn from, can someone help me and guide me into the right direction.. i have a huge motivation to get good at coding, anything information would be extremely helpful

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• ublas::bounded_vector<> being resized?

  - by n2liquid

  Now, seriously... I'll refrain from using bad words here because we're talking about the Boost fellows. It MUST be my mistake to see things this way, but I can't understand why, so I'll ask it here; maybe someone can enlighten me in this matter. Here it goes: uBLAS has this nice class template called bounded_vector<> that's used to create fixed-size vectors (or so I thought). From the Effective uBLAS wiki (http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?Effective_UBLAS): The default uBLAS vector and matrix types are of variable size. Many linear algebra problems involve vectors with fixed size. 2 and 3 elements are common in geometry! Fixed size storage (akin to C arrays) can be implemented efficiently as it does not involve the overheads (heap management) associated with dynamic storage. uBLAS implements fixed sizes by changing the underling storage of a vector/matrix to a "bounded_array" from the default "unbounded_array". Alright, this bounded_vector<> thing is used to free you from specifying the underlying storage of the vector to a bounded_array<> of the specified size. Here I ask you: doesn't it look like this bounded vector thing has fixed size to you? Well, it doesn't have. At first I felt betrayed by the wiki, but then I reconsidered the meaning of "bounded" and I think I can let it pass. But in case you, like me (I'm still uncertain), is still wondering if this makes sense, what I found out is that the bounded_vector<> actually can be resized, it may only not be greater than the size specified as template parameter. So, first off, do you think they've had a good reason not to make a real fixed<< size vector or matrix type? Do you think it's okay to "sell" this bounded -- as opposed to fixed-size -- vector to the users of my library as a "fixed-size" vector replacement, even named "Vector3" or "Vector2", like the Effective uBLAS wiki did? Do you think I should somehow implement a vector with fixed size for this purpose? If so, how? (Sorry, but I'm really new to uBLAS; just tried it today) I am developing a 3D game. Should uBLAS be used for the calculations involved in this ("hey, geometry!", per Effective uBLAS wiki)? What replacement would you suggest, if not? -- edit And just in case, yes, I've read this warning: It should be noted that this only changes the storage uBLAS uses for the vector3. uBLAS will still use all the same algorithm (which assume a variable size) to manipulate the vector3. In practice this seems to have no negative impact on speed. The above runs just as quickly as a hand crafted vector3 which does not use uBLAS. The only negative impact is that the vector3 always store a "size" member which in this case is redundant [or isn't it? I mean......]. I see it uses the same algorithm, assuming a variable size, but if an operation were to actually change its size, shouldn't it be stopped (assertion)? ublas::bounded_vector<float,3> v3; ublas::bounded_vector<float,2> v2; v3 = v2; std::cout << v3.size() << '\n'; // prints 2 Oh, come on, isn't this just plain betrayal?

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• JPA Entity Manager resource handling

  - by chiragshahkapadia

  Every time I call JPA method its creating entity and binding query. My persistence properties are: <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/> <property name="hibernate.cache.provider_class" value="net.sf.ehcache.hibernate.SingletonEhCacheProvider"/> <property name="hibernate.cache.use_second_level_cache" value="true"/> <property name="hibernate.cache.use_query_cache" value="true"/> And I am creating entity manager the way shown below: emf = Persistence.createEntityManagerFactory("pu"); em = emf.createEntityManager(); em = Persistence.createEntityManagerFactory("pu").createEntityManager(); Is there any nice way to manage entity manager resource instead create new every time or any property can set in persistence. Remember it's JPA. See below binding log every time : 15:35:15,527 INFO [AnnotationBinder] Binding entity from annotated class: * 15:35:15,527 INFO [QueryBinder] Binding Named query: * = * 15:35:15,527 INFO [QueryBinder] Binding Named query: * = * 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [QueryBinder] Binding Named query: 15:35:15,527 INFO [EntityBinder] Bind entity com.* on table * 15:35:15,542 INFO [HibernateSearchEventListenerRegister] Unable to find org.hibernate.search.event.FullTextIndexEventListener on the classpath. Hibernate Search is not enabled. 15:35:15,542 INFO [NamingHelper] JNDI InitialContext properties:{} 15:35:15,542 INFO [DatasourceConnectionProvider] Using datasource: 15:35:15,542 INFO [SettingsFactory] RDBMS: and Real Application Testing options 15:35:15,542 INFO [SettingsFactory] JDBC driver: Oracle JDBC driver, version: 9.2.0.1.0 15:35:15,542 INFO [Dialect] Using dialect: org.hibernate.dialect.Oracle10gDialect 15:35:15,542 INFO [TransactionFactoryFactory] Transaction strategy: org.hibernate.transaction.JDBCTransactionFactory 15:35:15,542 INFO [TransactionManagerLookupFactory] No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recomm ended) 15:35:15,542 INFO [SettingsFactory] Automatic flush during beforeCompletion(): disabled 15:35:15,542 INFO [SettingsFactory] Automatic session close at end of transaction: disabled 15:35:15,542 INFO [SettingsFactory] JDBC batch size: 15 15:35:15,542 INFO [SettingsFactory] JDBC batch updates for versioned data: disabled 15:35:15,542 INFO [SettingsFactory] Scrollable result sets: enabled 15:35:15,542 INFO [SettingsFactory] JDBC3 getGeneratedKeys(): disabled 15:35:15,542 INFO [SettingsFactory] Connection release mode: auto 15:35:15,542 INFO [SettingsFactory] Default batch fetch size: 1 15:35:15,542 INFO [SettingsFactory] Generate SQL with comments: disabled 15:35:15,542 INFO [SettingsFactory] Order SQL updates by primary key: disabled 15:35:15,542 INFO [SettingsFactory] Order SQL inserts for batching: disabled 15:35:15,542 INFO [SettingsFactory] Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory 15:35:15,542 INFO [ASTQueryTranslatorFactory] Using ASTQueryTranslatorFactory 15:35:15,542 INFO [SettingsFactory] Query language substitutions: {} 15:35:15,542 INFO [SettingsFactory] JPA-QL strict compliance: enabled 15:35:15,542 INFO [SettingsFactory] Second-level cache: enabled 15:35:15,542 INFO [SettingsFactory] Query cache: enabled 15:35:15,542 INFO [SettingsFactory] Cache region factory : org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge 15:35:15,542 INFO [RegionFactoryCacheProviderBridge] Cache provider: net.sf.ehcache.hibernate.SingletonEhCacheProvider 15:35:15,542 INFO [SettingsFactory] Optimize cache for minimal puts: disabled 15:35:15,542 INFO [SettingsFactory] Structured second-level cache entries: disabled 15:35:15,542 INFO [SettingsFactory] Query cache factory: org.hibernate.cache.StandardQueryCacheFactory 15:35:15,542 INFO [SettingsFactory] Statistics: disabled 15:35:15,542 INFO [SettingsFactory] Deleted entity synthetic identifier rollback: disabled 15:35:15,542 INFO [SettingsFactory] Default entity-mode: pojo 15:35:15,542 INFO [SettingsFactory] Named query checking : enabled 15:35:15,542 INFO [SessionFactoryImpl] building session factory 15:35:15,542 INFO [SessionFactoryObjectFactory] Not binding factory to JNDI, no JNDI name configured 15:35:15,542 INFO [UpdateTimestampsCache] starting update timestamps cache at region: org.hibernate.cache.UpdateTimestampsCache 15:35:15,542 INFO [StandardQueryCache] starting query cache at region: org.hibernate.cache.StandardQueryCache

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• dbms_xmlschema fail to validate with complexType

  - by Andrew

  Preface: This works on one Oracle 11gR1 (Solaris 64) database and not on a second and we can't figure out the difference between the two databases. Somehow the complexType causes the validation to fail with this error: ORA-31154: invalid XML document ORA-19202: Error occurred in XML processing LSX-00200: element "shiporder" not empty ORA-06512: at "SYS.XMLTYPE", line 354 ORA-06512: at line 13 But the schema is valid (passes this online test: http://www.xmlme.com/Validator.aspx) -- Cleanup any existing schema begin dbms_xmlschema.deleteschema('shiporder.xsd',dbms_xmlschema.DELETE_CASCADE); end; -- Define the problem schema (adapted from http://www.w3schools.com/schema/schema_example.asp) begin dbms_xmlschema.registerSchema('shiporder.xsd','<?xml version="1.0" encoding="ISO-8859-1" ?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="shiporder"> <xs:complexType> <xs:sequence> <xs:element name="orderperson" type="xs:string"/> </xs:sequence> </xs:complexType> </xs:element> </xs:schema>',owner=>'SCOTT'); end; -- Attempt to validate declare bbb xmltype; begin bbb := XMLType('<?xml version="1.0" encoding="ISO-8859-1"?> <shiporder xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="shiporder.xsd"> <orderperson>John Smith</orderperson> </shiporder>'); XMLType.schemaValidate(bbb); end; Now if I gut the schema definition and leave only a string in the XML then the validation passes: begin dbms_xmlschema.deleteschema('shiporder.xsd',dbms_xmlschema.DELETE_CASCADE); end; begin dbms_xmlschema.registerSchema('shiporder.xsd','<?xml version="1.0" encoding="ISO-8859-1" ?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="shiporder" type="xs:string"/> </xs:schema>',owner=>'SCOTT'); end; DECLARE xml XMLTYPE; BEGIN xml := XMLTYPE('<?xml version="1.0" encoding="ISO-8859-1"?> <shiporder xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="shiporder.xsd"> John Smith </shiporder>'); XMLTYPE.schemaValidate(xml); END;

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• What are the Options for Storing Hierarchical Data in a Relational Database?

  - by orangepips

  Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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• What does the `forall` keyword in Haskell/GHC do?

  - by JUST MY correct OPINION

  I've been banging my head on this one for (quite literally) years now. I'm beginning to kinda/sorta understand how the foreach keyword is used in so-called "existential types" like this: data ShowBox = forall s. Show s => SB s (This despite the confusingly-worded explanations of it in the fragments found all around the web.) This is only a subset, however, of how foreach is used and I simply cannot wrap my mind around its use in things like this: runST :: forall a. (forall s. ST s a) -> a Or explaining why these are different: foo :: (forall a. a -> a) -> (Char,Bool) bar :: forall a. ((a -> a) -> (Char, Bool)) Or the whole RankNTypes stuff that breaks my brain when "explained" in a way that makes me want to do that Samuel L. Jackson thing from Pulp Fiction. (Don't follow that link if you're easily offended by strong language.) The problem, really, is that I'm a dullard. I can't fathom the chicken scratchings (some call them "formulae") of the elite mathematicians that created this language seeing as my university years are over two decades behind me and I never actually had to put what I learnt into use in practice. I also tend to prefer clear, jargon-free English rather than the kinds of language which are normal in academic environments. Most of the explanations I attempt to read on this (the ones I can find through search engines) have these problems: They're incomplete. They explain one part of the use of this keyword (like "existential types") which makes me feel happy until I read code that uses it in a completely different way (like runST, foo and bar above). They're densely packed with assumptions that I've read the latest in whatever branch of discrete math, category theory or abstract algebra is popular this week. (If I never read the words "consult the paper whatever for details of implementation" again, it will be too soon.) They're written in ways that frequently turn even simple concepts into tortuously twisted and fractured grammar and semantics. (I suspect that the last two items are the biggest problem. I wouldn't know, though, since I'm too much a dullard to comprehend them.) It's been asked why Haskell never really caught on in industry. I suspect, in my own humble, unintelligent way, that my experience in figuring out one stupid little keyword -- a keyword that is increasingly ubiquitous in the libraries being written these days -- are also part of the answer to that question. It's hard for a language to catch on when even its individual keywords cause years-long quests to comprehend. Years-long quests which end in failure. So... On to the actual question. Can anybody completely explain the foreach keyword in clear, plain English (or, if it exists somewhere, point to such a clear explanation which I've missed) that doesn't assume I'm a mathematician steeped in the jargon?

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• Cannot figure out how to take in generic parameters for an Enterprise Framework library sql statemen

  - by KallDrexx

  I have written a specialized class to wrap up the enterprise library database functionality for easier usage. The reasoning for using the Enterprise Library is because my applications commonly connect to both oracle and sql server database systems. My wrapper handles both creating connection strings on the fly, connecting, and executing queries allowing my main code to only have to write a few lines of code to do database stuff and deal with error handling. As an example my ExecuteNonQuery method has the following declaration: /// <summary> /// Executes a query that returns no results (e.g. insert or update statements) /// </summary> /// <param name="sqlQuery"></param> /// <param name="parameters">Hashtable containing all the parameters for the query</param> /// <returns>The total number of records modified, -1 if an error occurred </returns> public int ExecuteNonQuery(string sqlQuery, Hashtable parameters) { // Make sure we are connected to the database if (!IsConnected) { ErrorHandler("Attempted to run a query without being connected to a database.", ErrorSeverity.Critical); return -1; } // Form the command DbCommand dbCommand = _database.GetSqlStringCommand(sqlQuery); // Add all the paramters foreach (string key in parameters.Keys) { if (parameters[key] == null) _database.AddInParameter(dbCommand, key, DbType.Object, null); else _database.AddInParameter(dbCommand, key, DbType.Object, parameters[key].ToString()); } return _database.ExecuteNonQuery(dbCommand); } _database is defined as private Database _database;. Hashtable parameters are created via code similar to p.Add("@param", value);. the issue I am having is that it seems that with enterprise library database framework you must declare the dbType of each parameter. This isn't an issue when you are calling the database code directly when forming the paramters but doesn't work for creating a generic abstraction class such as I have. In order to try and get around that I thought I could just use DbType.Object and figure the DB will figure it out based on the columns the sql is working with. Unfortunately, this is not the case as I get the following error: Implicit conversion from data type sql_variant to varchar is not allowed. Use the CONVERT function to run this query Is there any way to use generic parameters in a wrapper class or am I just going to have to move all my DB code into my main classes?

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• Internet Explorer buggy when accessing a custom weblogic provider

  - by James

  I've created a custom Weblogic Security Authentication Provider on version 10.3 that includes a custom login module to validate users. As part of the provider, I've implemented the ServletAuthenticationFilter and added one filter. The filter acts as a common log on page for all the applications within the domain. When we access any secured URLs by entering them in the address bar, this works fine in IE and Firefox. But when we bookmark the link in IE an odd thing happens. If I click the bookmark, you will see our log on page, then after you've successfully logged into the system the basic auth page will display, even though the user is already authenticated. This never happens in Firefox, only IE. It's also intermittent. 1 time out of 5 IE will correctly redirect and not show the basic auth window. Firefox and Opera will correctly redirect everytime. We've captured the response headers and compared the success and failures, they are identical. final boolean isAuthenticated = authenticateUser(userName, password, req); // Send user on to the original URL if (isAuthenticated) { res.sendRedirect(targetURL); return; } As you can see, once the user is authenticated I do a redirect to the original URL. Is there a step I'm missing? The authenticateUser() method is taken verbatim from an example in Oracle's documents. private boolean authenticateUser(final String userName, final String password, HttpServletRequest request) { boolean results; try { ServletAuthentication.login(new CallbackHandler() { @Override public void handle(Callback[] callbacks) throws IOException, UnsupportedCallbackException { for (Callback callback : callbacks) { if (callback instanceof NameCallback) { NameCallback nameCallback = (NameCallback) callback; nameCallback.setName(userName); } if (callback instanceof PasswordCallback) { PasswordCallback passwordCallback = (PasswordCallback) callback; passwordCallback.setPassword(password.toCharArray()); } } } }, request); results = true; } catch (LoginException e) { results = false; } return results; I am asking the question here because I don't know if the issue is with the Weblogic config or the code. If this question is more suited to ServerFault please let me know and I will post there. It is odd that it works everytime in Firefox and Opera but not in Internet Explorer. I wish that not using Internet Explorer was an option but it is currently the company standard. Any help or direction would be appreciated. I have tested against IE 6 & 8 and deployed the custom provider on 3 different environments and I can still reproduce the bug.

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• Where should I create my DbCommand instances?

  - by Domenic

  I seemingly have two choices: Make my class implement IDisposable. Create my DbCommand instances as private readonly fields, and in the constructor, add the parameters that they use. Whenever I want to write to the database, bind to these parameters (reusing the same command instances), set the Connection and Transaction properties, then call ExecuteNonQuery. In the Dispose method, call Dispose on each of these fields. Each time I want to write to the database, write using(var cmd = new DbCommand("...", connection, transaction)) around the usage of the command, and add parameters and bind to them every time as well, before calling ExecuteNonQuery. I assume I don't need a new command for each query, just a new command for each time I open the database (right?). Both of these seem somewhat inelegant and possibly incorrect. For #1, it is annoying for my users that I this class is now IDisposable just because I have used a few DbCommands (which should be an implementation detail that they don't care about). I also am somewhat suspicious that keeping a DbCommand instance around might inadvertently lock the database or something? For #2, it feels like I'm doing a lot of work (in terms of .NET objects) each time I want to write to the database, especially with the parameter-adding. It seems like I create the same object every time, which just feels like bad practice. For reference, here is my current code, using #1: using System; using System.Net; using System.Data.SQLite; public class Class1 : IDisposable { private readonly SQLiteCommand updateCookie = new SQLiteCommand("UPDATE moz_cookies SET value = @value, expiry = @expiry, isSecure = @isSecure, isHttpOnly = @isHttpOnly WHERE name = @name AND host = @host AND path = @path"); public Class1() { this.updateCookie.Parameters.AddRange(new[] { new SQLiteParameter("@name"), new SQLiteParameter("@value"), new SQLiteParameter("@host"), new SQLiteParameter("@path"), new SQLiteParameter("@expiry"), new SQLiteParameter("@isSecure"), new SQLiteParameter("@isHttpOnly") }); } private static void BindDbCommandToMozillaCookie(DbCommand command, Cookie cookie) { long expiresSeconds = (long)cookie.Expires.TotalSeconds; command.Parameters["@name"].Value = cookie.Name; command.Parameters["@value"].Value = cookie.Value; command.Parameters["@host"].Value = cookie.Domain; command.Parameters["@path"].Value = cookie.Path; command.Parameters["@expiry"].Value = expiresSeconds; command.Parameters["@isSecure"].Value = cookie.Secure; command.Parameters["@isHttpOnly"].Value = cookie.HttpOnly; } public void WriteCurrentCookiesToMozillaBasedBrowserSqlite(string databaseFilename) { using (SQLiteConnection connection = new SQLiteConnection("Data Source=" + databaseFilename)) { connection.Open(); using (SQLiteTransaction transaction = connection.BeginTransaction()) { this.updateCookie.Connection = connection; this.updateCookie.Transaction = transaction; foreach (Cookie cookie in SomeOtherClass.GetCookieArray()) { Class1.BindDbCommandToMozillaCookie(this.updateCookie, cookie); this.updateCookie.ExecuteNonQuery(); } transaction.Commit(); } } } #region IDisposable implementation protected virtual void Dispose(bool disposing) { if (!this.disposed && disposing) { this.updateCookie.Dispose(); } this.disposed = true; } public void Dispose() { this.Dispose(true); GC.SuppressFinalize(this); } ~Class1() { this.Dispose(false); } private bool disposed; #endregion }

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