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• spring JDBC

  - by Adhir

  I am getting the following exception whe using derby to do a UPDATE in oracle Database org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.derby.client.am.DisconnectException: A communication error has been detected. Communication protocol being used: Reply.fill(). Communication API being used: InputStream.read(). Location where the error was detected: insufficient data. Communication function detecting the error: *. Protocol specific error codes(s) TCP/IP SOCKETS at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:82) at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:522) at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:737) at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:795) at org.springframework.jdbc.core.JdbcTemplate.update(JdbcTemplate.java:803) at com.poc.data.dao.UserDerbyDao.create(UserDerbyDao.java:19) at com.poc.register.RegisterUtil.registerUser(RegisterUtil.java:34) at com.poc.service.MyService.doRegister(MyService.java:108) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:175) at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:67) at com.sun.jersey.server.impl.uri.rules.HttpMethodRule.accept(HttpMethodRule.java:166) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:114) at com.sun.jersey.server.impl.uri.rules.ResourceClassRule.accept(ResourceClassRule.java:74) at com.sun.jersey.server.impl.uri.rules.RightHandPathRule.accept(RightHandPathRule.java:114) at com.sun.jersey.server.impl.uri.rules.RootResourceClassesRule.accept(RootResourceClassesRule.java:66) at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:658) at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:616) at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:607) at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:309) at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:425) at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:590) at javax.servlet.http.HttpServlet.service(HttpServlet.java:806) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447) at java.lang.Thread.run(Unknown Source) Caused by: org.apache.derby.client.am.DisconnectException: A communication error has been detected. Communication protocol being used: Reply.fill(). Communication API being used: InputStream.read(). Location where the error was detected: insufficient data. Communication function detecting the error: *. Protocol specific error codes(s) TCP/IP SOCKETS at org.apache.derby.client.net.NetAgent.throwCommunicationsFailure(Unknown Source) at org.apache.derby.client.net.Reply.fill(Unknown Source) at org.apache.derby.client.net.Reply.ensureALayerDataInBuffer(Unknown Source) at org.apache.derby.client.net.Reply.readDssHeader(Unknown Source) at org.apache.derby.client.net.Reply.startSameIdChainParse(Unknown Source) at org.apache.derby.client.net.NetConnectionReply.readExchangeServerAttributes(Unknown Source) at org.apache.derby.client.net.NetConnection.readServerAttributesAndKeyExchange(Unknown Source) at org.apache.derby.client.net.NetConnection.flowServerAttributesAndKeyExchange(Unknown Source) at org.apache.derby.client.net.NetConnection.flowUSRIDPWDconnect(Unknown Source) at org.apache.derby.client.net.NetConnection.flowConnect(Unknown Source) at org.apache.derby.client.net.NetConnection.(Unknown Source) at org.apache.derby.jdbc.ClientDriver.connect(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at java.sql.DriverManager.getConnection(Unknown Source) at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:291) at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:277) at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnectionFromDriverManager(DriverManagerDataSource.java:259) at org.springframework.jdbc.datasource.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:240) at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:113) at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:79) ... 37 more Any help Thanks in advance Adhir

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• How to overcome shortcomings in reporting from EAV database?

  - by David Archer

  The major shortcomings with Entity-Attribute-Value database designs in SQL all seem to be related to being able to query and report on the data efficiently and quickly. Most of the information I read on the subject warn against implementing EAV due to these problems and the commonality of querying/reporting for almost all applications. I am currently designing a system where almost all the fields necessary for data storage are not known at design/compile time and are defined by the end-user of the system. EAV seems like a good fit for this requirement but due to the problems I've read about, I am hesitant in implementing it as there are also some pretty heavy reporting requirements for this system as well. I think I've come up with a way around this but would like to pose the question to the SO community. Given that typical normalized database (OLTP) still isn't always the best option for running reports, a good practice seems to be having a "reporting" database (OLAP) where the data from the normalized database is copied to, indexed extensively, and possibly denormalized for easier querying. Could the same idea be used to work around the shortcomings of an EAV design? The main downside I see are the increased complexity of transferring the data from the EAV database to reporting as you may end up having to alter the tables in the reporting database as new fields are defined in the EAV database. But that is hardly impossible and seems to be an acceptable tradeoff for the increased flexibility given by the EAV design. This downside also exists if I use a non-SQL data store (i.e. CouchDB or similar) for the main data storage since all the standard reporting tools are expecting a SQL backend to query against. Do the issues with EAV systems mostly go away if you have a seperate reporting database for querying? EDIT: Thanks for the comments so far. One of the important things about the system I'm working on it that I'm really only talking about using EAV for one of the entities, not everything in the system. The whole gist of the system is to be able to pull data from multiple disparate sources that are not known ahead of time and crunch the data to come up with some "best known" data about a particular entity. So every "field" I'm dealing with is multi-valued and I'm also required to track history for each. The normalized design for this ends up being 1 table per field which makes querying it kind of painful anyway. Here are the table schemas and sample data I'm looking at (obviously changed from what I'm working on but I think it illustrates the point well): EAV Tables Person ------------------- - Id - Name - ------------------- - 123 - Joe Smith - ------------------- Person_Value ------------------------------------------------------------------- - PersonId - Source - Field - Value - EffectiveDate - ------------------------------------------------------------------- - 123 - CIA - HomeAddress - 123 Cherry Ln - 2010-03-26 - - 123 - DMV - HomeAddress - 561 Stoney Rd - 2010-02-15 - - 123 - FBI - HomeAddress - 676 Lancas Dr - 2010-03-01 - ------------------------------------------------------------------- Reporting Table Person_Denormalized ---------------------------------------------------------------------------------------- - Id - Name - HomeAddress - HomeAddress_Confidence - HomeAddress_EffectiveDate - ---------------------------------------------------------------------------------------- - 123 - Joe Smith - 123 Cherry Ln - 0.713 - 2010-03-26 - ---------------------------------------------------------------------------------------- Normalized Design Person ------------------- - Id - Name - ------------------- - 123 - Joe Smith - ------------------- Person_HomeAddress ------------------------------------------------------ - PersonId - Source - Value - Effective Date - ------------------------------------------------------ - 123 - CIA - 123 Cherry Ln - 2010-03-26 - - 123 - DMV - 561 Stoney Rd - 2010-02-15 - - 123 - FBI - 676 Lancas Dr - 2010-03-01 - ------------------------------------------------------ The "Confidence" field here is generated using logic that cannot be expressed easily (if at all) using SQL so my most common operation besides inserting new values will be pulling ALL data about a person for all fields so I can generate the record for the reporting table. This is actually easier in the EAV model as I can do a single query. In the normalized design, I end up having to do 1 query per field to avoid a massive cartesian product from joining them all together.

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• Configuring hibernate.reveng.xml to detect a sequence PK generator with hibernate3-maven-plugin and

  - by mmm

  Hi, is there a way to configure hibernate3-maven-plugin so that a sequence generator is detected for a primary-key? I'm using a bottom-up approach for hibernate configuration (which means letting hibernate-tools generate the hibernate configuration using a jdbc-connection for you via reverse-engineering on an existing database schema). I've read this, but also this already (those two can be unrelated, but can also leave a hint). My hibernate.reveng.xml is the following: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-reverse-engineering SYSTEM "http://hibernate.sourceforge.net/hibernate-reverse-engineering-3.0.dtd" > <hibernate-reverse-engineering> <table name="ORDERS"> <primary-key> <!-- setting up a specific id generator for a table --> <generator class="sequence"> <param name="sequence">ORDERS_ORDER_ID_seq</param> </generator> <key-column name="ORDER_ID"/> </primary-key> </table> </hibernate-reverse-engineering> And I'm expecting it to generate an Orders.hbm.xml file like this: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated 2010-06-06 18:55:42 by Hibernate Tools 3.2.2.GA --> <hibernate-mapping> <class name="some.package.Orders" table="orders" schema="public"> <id name="orderId" type="long"> <column name="order_id" /> <generator class="sequence"> <param name="sequence">ORDERS_ORDER_ID_seq</param> </generator> </id> ... </class> </hibernate-mapping> ...but receiving this instead: <?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!-- Generated 2010-06-06 18:55:42 by Hibernate Tools 3.2.2.GA --> <hibernate-mapping> <class name="some.package.Orders" table="orders" schema="public"> <id name="orderId" type="long"> <column name="order_id" /> <generator class="assigned" /> </id> ... </class> </hibernate-mapping> I know my hibernate.reveng.xml is being read by hibernate3-maven-plugin, as I experience maven errors whenever syntax errors appear in the file, so pom.xml seems to be correct and hibernate.reveng.xml syntactically correct. Any clues?

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• JAVA: POST data via HTTPS does not seem to get sent?

  - by ostollmann

  Hi guys (and girls), I have a problem POSTing data via HTTPS in Java. The server response is the same whether or not I send 'query'. Maybe someone can point out what the problem is... Thanks! Main class: package bind; public class Main { public static final String urlString = "https://www.sms.ethz.ch/cgi-bin/sms/send.pl"; public static void main(String[] args) { Message msg = new Message("Alles klar?"); URL url = new URL(urlString); String[][] values = new String[3][2]; values[0][0] = "action"; values[0][1] = "listoriginators"; values[1][0] = "username"; values[1][1] = "xxxxxx"; values[2][0] = "password"; values[2][1] = "xxxxxx"; Query query = new Query(values); System.out.println("Query: " + query.getQuery()); Request request = new Request(url.getURL(), query.getQuery()); } } Request class: package bind; public class Request { static private int ic = 0; private URL url; protected Request(java.net.URL URL, String query){ ic++; if(CONSTANTS.SHOW_LOGS) { System.out.println("log: new instance of 'Message'"); } // connect try { System.setProperty("java.protocol.handler.pkgs", "com.sun.net.ssl.internal.www.protocol"); java.security.Security.addProvider(new com.sun.net.ssl.internal.ssl.Provider()); javax.net.ssl.HttpsURLConnection connection = (javax.net.ssl.HttpsURLConnection) URL.openConnection(); connection.setDoInput(true); connection.setDoOutput(true); connection.setRequestMethod("POST"); connection.setFollowRedirects(true); connection.setRequestProperty("Content-Length", String.valueOf(query.length())); connection.setRequestProperty("Content-Type", "application/x-www- form-urlencoded"); connection.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)"); java.io.DataOutputStream output = new java.io.DataOutputStream(connection.getOutputStream()); output.writeBytes(query); // <<-- NOTHING CHANGES IF I COMMENT THIS OUT OR NOT !!??!?! System.out.println("log: response code: " + connection.getResponseCode()); System.out.println("log: response message: " + connection.getResponseMessage()); java.io.DataInputStream input = new java.io.DataInputStream(connection.getInputStream()); for(int i = input.read(); i != -1; i = input.read()) { System.out.print((char)i); } System.out.print("\n"); input.close(); } catch(java.io.IOException e) { if(CONSTANTS.SHOW_LOGS) { System.out.println("error: unable to connect"); System.out.println(e); e.printStackTrace(); } } } } URL Class: public class URL { static private int ic = 0; private String URLString; private java.net.URL url; protected URL(String a_url){ ic++; if(CONSTANTS.SHOW_LOGS) { System.out.println("log: new instance of 'URL'"); } setURLString(a_url); createURL(); } private void setURLString(String a_url) { URLString = a_url; } private void createURL() { try { url = new java.net.URL(URLString); } catch(java.net.MalformedURLException e) { System.out.println("error: invalid URL"); System.out.println(e); e.printStackTrace(); } } private void showURL() { System.out.println("URL: " + url.getHost() + url.getPath()); } public java.net.URL getURL() { return url; } } PS: mostly from here: http://www.java-samples.com/java/POST-toHTTPS-url-free-java-sample-program.htm

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• Android Dev Help: Saving an image from Res/raw or Asset folder to the Sd card

  - by Lucy

  Android Development Query Hello, I wonder if anyone could help me, i am trying to save an image (jpg or png) from the res/raw or assets folder to the SD card location (/sdcard/DCIM/). I have been following a tutorial which can save an image from a URL to the SD card Root, but i have looked everywhere to be able to save from res/raw or asset folder instead, and to a differnet location onthe sd card /sdcard/DCIM/ Here is the code, can anyone show me how to do the above from this? Thanks Lucy public class home extends Activity { private File file; private String imgNumber; private Button btnDownload; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); btnDownload=(Button)findViewById(R.id.btnDownload); btnDownload.setOnClickListener(new OnClickListener() { public void onClick(View v) { btnDownload.setText("Download is in Progress."); String savedFilePath=Download("http://www.domain.com/android1.png"); Toast.makeText(getApplicationContext(), "File is Saved in "+savedFilePath, 1000).show(); if(savedFilePath!=null) { btnDownload.setText("Download Completed."); } } }); } public String Download(String Url) { String filepath=null; try { //set the download URL, a url that points to a file on the internet //this is the file to be downloaded URL url = new URL(Url); //create the new connection HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); //set up some things on the connection urlConnection.setRequestMethod("GET"); urlConnection.setDoOutput(true); //and connect! urlConnection.connect(); //set the path where we want to save the file //in this case, going to save it on the root directory of the //sd card. File SDCardRoot = Environment.getExternalStorageDirectory(); //create a new file, specifying the path, and the filename //which we want to save the file as. String filename= "download_"+System.currentTimeMillis()+".png"; // you can download to any type of file ex:.jpeg (image) ,.txt(text file),.mp3 (audio file) Log.i("Local filename:",""+filename); file = new File(SDCardRoot,filename); if(file.createNewFile()) { file.createNewFile(); } //this will be used to write the downloaded data into the file we created FileOutputStream fileOutput = new FileOutputStream(file); //this will be used in reading the data from the internet InputStream inputStream = urlConnection.getInputStream(); //this is the total size of the file int totalSize = urlConnection.getContentLength(); //variable to store total downloaded bytes int downloadedSize = 0; //create a buffer... byte[] buffer = new byte[1024]; int bufferLength = 0; //used to store a temporary size of the buffer //now, read through the input buffer and write the contents to the file while ( (bufferLength = inputStream.read(buffer)) > 0 ) { //add the data in the buffer to the file in the file output stream (the file on the sd card fileOutput.write(buffer, 0, bufferLength); //add up the size so we know how much is downloaded downloadedSize += bufferLength; //this is where you would do something to report the prgress, like this maybe Log.i("Progress:","downloadedSize:"+downloadedSize+"totalSize:"+ totalSize) ; btnDownload.setText("download Status:"+downloadedSize+" / "+totalSize); } //close the output stream when done fileOutput.close(); if(downloadedSize==totalSize) filepath=file.getPath(); //catch some possible errors... } catch (MalformedURLException e) { e.printStackTrace(); } catch (IOException e) { filepath=null; btnDownload.setText("Internet Connection Failed.\n"+e.getMessage()); e.printStackTrace(); } Log.i("filepath:"," "+filepath) ; return filepath; } }

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• SQL server deadlock between INSERT and SELECT statement

  - by dtroy

  Hi! I've got a problem with multiple deadlocks on SQL server 2005. This one is between an INSERT and a SELECT statement. There are two tables. Table 1 and Table2. Table2 has Table1's PK (table1_id) as foreign key. Index on table1_id is clustered. The INSERT inserts a single row into table2 at a time. The SELCET joins the 2 tables. (it's a long query which might take up to 12 secs to run) According to my understanding (and experiments) the INSERT should acquire an IS lock on table1 to check referential integrity (which should not cause a deadlock). But, in this case it acquired an IX page lock The deadlock report: <deadlock-list> <deadlock victim="process968898"> <process-list> <process id="process8db1f8" taskpriority="0" logused="2424" waitresource="OBJECT: 5:789577851:0 " waittime="12390" ownerId="61831512" transactionname="user_transaction" lasttranstarted="2010-04-16T07:10:13.347" XDES="0x222a8250" lockMode="IX" schedulerid="1" kpid="3764" status="suspended" spid="52" sbid="0" ecid="0" priority="0" transcount="2" lastbatchstarted="2010-04-16T07:10:13.350" lastbatchcompleted="2010-04-16T07:10:13.347" clientapp=".Net SqlClient Data Provider" hostname="VIDEV01-B-ME" hostpid="3040" loginname="DatabaseName" isolationlevel="read uncommitted (1)" xactid="61831512" currentdb="5" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056"> <executionStack> <frame procname="DatabaseName.dbo.prcTable2_Insert" line="18" stmtstart="576" stmtend="1148" sqlhandle="0x0300050079e62d06e9307f000b9d00000100000000000000"> INSERT INTO dbo.Table2 ( f1, table1_id, f2 ) VALUES ( @p1, @p_DocumentVersionID, @p1 ) </frame> </executionStack> <inputbuf> Proc [Database Id = 5 Object Id = 103671417] </inputbuf> </process> <process id="process968898" taskpriority="0" logused="0" waitresource="PAGE: 5:1:46510" waittime="7625" ownerId="61831406" transactionname="INSERT" lasttranstarted="2010-04-16T07:10:12.717" XDES="0x418ec00" lockMode="S" schedulerid="2" kpid="1724" status="suspended" spid="53" sbid="0" ecid="0" priority="0" transcount="2" lastbatchstarted="2010-04-16T07:10:12.713" lastbatchcompleted="2010-04-16T07:10:12.713" clientapp=".Net SqlClient Data Provider" hostname="VIDEV01-B-ME" hostpid="3040" loginname="DatabaseName" isolationlevel="read committed (2)" xactid="61831406" currentdb="5" lockTimeout="4294967295" clientoption1="671088672" clientoption2="128056"> <executionStack> <frame procname="DatabaseName.dbo.prcGetList" line="64" stmtstart="3548" stmtend="11570" sqlhandle="0x03000500dbcec17e8d267f000b9d00000100000000000000"> <!-- XXXXXXXXXXXXXX...SELECT STATEMENT WITH Multiple joins including both Table2 table 1 and .... XXXXXXXXXXXXXXX --> </frame> </executionStack> <inputbuf> Proc [Database Id = 5 Object Id = 2126630619] </inputbuf> </process> </process-list> <resource-list> <pagelock fileid="1" pageid="46510" dbid="5" objectname="DatabaseName.dbo.table1" id="lock6236bc0" mode="IX" associatedObjectId="72057594042908672"> <owner-list> <owner id="process8db1f8" mode="IX"/> </owner-list> <waiter-list> <waiter id="process968898" mode="S" requestType="wait"/> </waiter-list> </pagelock> <objectlock lockPartition="0" objid="789577851" subresource="FULL" dbid="5" objectname="DatabaseName.dbo.Table2" id="lock970a240" mode="S" associatedObjectId="789577851"> <owner-list> <owner id="process968898" mode="S"/> </owner-list> <waiter-list> <waiter id="process8db1f8" mode="IX" requestType="wait"/> </waiter-list> </objectlock> </resource-list> </deadlock> </deadlock-list> Can anyone explain why the INSERT gets the IX page lock ? Am I not reading the deadlock report properly? BTW, I have not managed to reproduce this issue. Thanks!

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• Optimal storage of data structure for fast lookup and persistence

  - by Mikael Svenson

  Scenario I have the following methods: public void AddItemSecurity(int itemId, int[] userIds) public int[] GetValidItemIds(int userId) Initially I'm thinking storage on the form: itemId -> userId, userId, userId and userId -> itemId, itemId, itemId AddItemSecurity is based on how I get data from a third party API, GetValidItemIds is how I want to use it at runtime. There are potentially 2000 users and 10 million items. Item id's are on the form: 2007123456, 2010001234 (10 digits where first four represent the year). AddItemSecurity does not have to perform super fast, but GetValidIds needs to be subsecond. Also, if there is an update on an existing itemId I need to remove that itemId for users no longer in the list. I'm trying to think about how I should store this in an optimal fashion. Preferably on disk (with caching), but I want the code maintainable and clean. If the item id's had started at 0, I thought about creating a byte array the length of MaxItemId / 8 for each user, and set a true/false bit if the item was present or not. That would limit the array length to little over 1mb per user and give fast lookups as well as an easy way to update the list per user. By persisting this as Memory Mapped Files with the .Net 4 framework I think I would get decent caching as well (if the machine has enough RAM) without implementing caching logic myself. Parsing the id, stripping out the year, and store an array per year could be a solution. The ItemId - UserId[] list can be serialized directly to disk and read/write with a normal FileStream in order to persist the list and diff it when there are changes. Each time a new user is added all the lists have to updated as well, but this can be done nightly. Question Should I continue to try out this approach, or are there other paths which should be explored as well? I'm thinking SQL server will not perform fast enough, and it would give an overhead (at least if it's hosted on a different server), but my assumptions might be wrong. Any thought or insights on the matter is appreciated. And I want to try to solve it without adding too much hardware :) [Update 2010-03-31] I have now tested with SQL server 2008 under the following conditions. Table with two columns (userid,itemid) both are Int Clustered index on the two columns Added ~800.000 items for 180 users - Total of 144 million rows Allocated 4gb ram for SQL server Dual Core 2.66ghz laptop SSD disk Use a SqlDataReader to read all itemid's into a List Loop over all users If I run one thread it averages on 0.2 seconds. When I add a second thread it goes up to 0.4 seconds, which is still ok. From there on the results are decreasing. Adding a third thread brings alot of the queries up to 2 seonds. A forth thread, up to 4 seconds, a fifth spikes some of the queries up to 50 seconds. The CPU is roofing while this is going on, even on one thread. My test app takes some due to the speedy loop, and sql the rest. Which leads me to the conclusion that it won't scale very well. At least not on my tested hardware. Are there ways to optimize the database, say storing an array of int's per user instead of one record per item. But this makes it harder to remove items.

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• Chaining CSS classes in IE6 - Trying to find a jQuery solution?

  - by Mike Baxter

  Right, perhaps I ask the impossible? I consider myself fairly new to Javscript and jQuery, but that being said, I have written some fairly complex code recently so I am definitely getting there... however I am now possed with a rather interesting issue at my current freelance contract. The previous web coder has taken a Grid-960 approach to the HTML and as a result has used chained classes to style many of the elements. The example below is typical of what can be found in the code: <div class='blocks four-col-1 orange highlight'>Some content</div> And in the css there will be different declarations for: (not actual css... but close enough) .blocks {margin-right:10px;} .orange {background-image:url(someimage.jpg);} .highlight {font-weight:bold;} .four-col-1 {width:300px;} and to make matters worse... this is in the CSS: .blocks.orange.highlight {background-colour:#dd00ff;} Anyone not familiar with this particular bug can read more on it here: http://www.ryanbrill.com/archives/multiple-classes-in-ie/ it is very real and very annoying. Without wanting to go into the merrits of not chaining classes (I told them this, but it is no longer feasible to change their approach... 100 hand coded pages into a 150 page website, no CMS... sigh) and without the luxury of being able to change the way these blocks are styled... can anyone advise me on the complexity and benefits between any of my below proposed approaches or possible other options that would adequately solve this problem. Potential Solution 1 Using conditional comments I am considering loading a jquery script only for IE6 that: Reads the class of all divs in a certain section of the page and pushes to an array creates empty boxes off screen with only one of the classes applied at a time Reads the applied CSS values for each box Re-applies these styles to the individual box, somehow bearing in mind the order in which they are called and overwriting conflicting instructions as required Potential Solution 2 read the class of all divs in a certain section of the page and push to an array Scan the document for links to style sheets Ajax grab the stylesheets and traverse looking for matching names to those in class array Apply styles as needed Potential Solution 3 Create an IE6 only stylesheet containing the exact style to be applied as a unique name (ie: class='blocks orange highlight' becomes class='blocks-orange-highlight') Traverse the document in IE6 and convert all spaces in class declarations to hyphens and reapply classes based on new style name Summary: Solution 1 allows the people at this company to apply any styles in the future and the script will adjust as needed. However it does not allow for the chained style to be added, only the individual style... it is also processor intensive and time consuming, but also the most likely to be converted into a plugin that could be used the world over Solution 2 is a potential nightmare to code. But again will allow for an endless number of updates without breaking Solution 3 will require someone at the companty to hardcode the new styles every time they make a change, and if they don't, IE6 will break. Ironically the site, whilst needing to conform to IE6 in a limited manner, does not need to run wihtout javascript (they've made the call... have JS or go away), so consider all jQuery and JS solutions to be 'game on'. Did I mention how much i hate IE6? Anyway... any thoughts or comments would be appreciated. I will continue to develop my own solution and if I discover one that can be turned into a jQuery plugin I will post it here in the comments. Regards, Mike.

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• The best cross platform (portable) arbitrary precision math library

  - by Siu Ching Pong - Asuka Kenji

  Dear ninjas / hackers / wizards, I'm looking for a good arbitrary precision math library in C or C++. Could you please give me some advices / suggestions? The primary requirements: It MUST handle arbitrarily big integers (my primary interest is on integers). In case that you don't know what the word arbitrarily big means, imagine something like 100000! (the factorial of 100000). The precision MUST NOT NEED to be specified during library initialization / object creation. The precision should ONLY be constrained by the available resources of the system. It SHOULD utilize the full power of the platform, and should handle "small" numbers natively. That means on a 64-bit platform, calculating 2^33 + 2^32 should use the available 64-bit CPU instructions. The library SHOULD NOT calculate this in the same way as it does with 2^66 + 2^65 on the same platform. It MUST handle addition (+), subtraction (-), multiplication (*), integer division (/), remainder (%), power (**), increment (++), decrement (--), gcd(), factorial(), and other common integer arithmetic calculations efficiently. Ability to handle functions like sqrt() (square root), log() (logarithm) that do not produce integer results is a plus. Ability to handle symbolic computations is even better. Here are what I found so far: Java's BigInteger and BigDecimal class: I have been using these so far. I have read the source code, but I don't understand the math underneath. It may be based on theories / algorithms that I have never learnt. The built-in integer type or in core libraries of bc / Python / Ruby / Haskell / Lisp / Erlang / OCaml / PHP / some other languages: I have ever used some of these, but I have no idea on which library they are using, or which kind of implementation they are using. What I have already known: Using a char as a decimal digit, and a char* as a decimal string and do calculations on the digits using a for-loop. Using an int (or a long int, or a long long) as a basic "unit" and an array of it as an arbitrary long integer, and do calculations on the elements using a for-loop. Booth's multiplication algorithm What I don't know: Printing the binary array mentioned above in decimal without using naive methods. Example of a naive method: (1) add the bits from the lowest to the highest: 1, 2, 4, 8, 16, 32, ... (2) use a char* string mentioned above to store the intermediate decimal results). What I appreciate: Good comparisons on GMP, MPFR, decNumber (or other libraries that are good in your opinion). Good suggestions on books / articles that I should read. For example, an illustration with figures on how a un-naive arbitrarily long binary to decimal conversion algorithm works is good. Any help. Please DO NOT answer this question if: you think using a double (or a long double, or a long long double) can solve this problem easily. If you do think so, it means that you don't understand the issue under discussion. you have no experience on arbitrary precision mathematics. Thank you in advance! Asuka Kenji

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• Delphi - Why is my global variable "inacessible" when i debug

  - by Antoine Lpy

  I'm building an application that contains around 30 Forms. I need to manage sessions, so I would like to have a global LoggedInUser variable accessible from all forms. I read "David Heffernan"'s post about global variables, and how to avoid them but I thought it would be easier to have a global User variable rather than 30 forms having their own User variable. So i have a unit : GlobalVars unit GlobalVars; interface uses User; // I defined my TUser class in a unit called User var LoggedInUser: TUser; implementation initialization LoggedInUser:= TUser.Create; finalization LoggedInUser.Free; end. Then in my LoginForm's LoginBtnClick procedure I do : unit FormLogin; interface uses [...],User; type TForm1 = class(TForm) [...] procedure LoginBtnClick(Sender: TObject); private { Déclarations privées } public end; var Form1: TForm1; AureliusConnection : IDBConnection; implementation {$R *.fmx} uses [...]GlobalVars; procedure TForm1.LoginBtnClick(Sender: TObject); var Manager : TObjectManager; MyCriteria: TCriteria<TUser>; u : TUser; begin Manager := TObjectManageR.Create(AureliusConnection); MyCriteria :=Manager.Find<TUtilisateur> .Add(TExpression.Eq('login',LoginEdit.Text)) .Add(TExpression.Eq('password',PasswordEdit.Text)); u := MyCriteria.UniqueResult; if u = nil then MessageDlg('Login ou mot de passe incorrect',TMsgDlgType.mtError,[TMsgDlgBtn.mbOK],0) else begin LoggedInUser:=u; //Here I assign my local User data to my global User variable Form1.Destroy; A00Form.visible:=true; end; Manager.Free; end; Then in another form I would like to access this LoggedInUser object in the Menu1BtnClick procedure : Unit C01_Deviations; interface uses System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants, FMX.Types, FMX.Graphics, FMX.Controls, FMX.Forms, FMX.Dialogs, FMX.StdCtrls, FMX.ListView.Types, FMX.ListView, FMX.Objects, FMX.Layouts, FMX.Edit, FMX.Ani; type TC01Form = class(TForm) [...] Menu1Btn: TButton; [...] procedure Menu1BtnClick(Sender: TObject); private { Déclarations privées } public { Déclarations publiques } end; var C01Form: TC01Form; implementation uses [...]User,GlobalVars; {$R *.fmx} procedure TC01Form.Menu1BtnClick(Sender: TObject); var Assoc : TUtilisateur_FonctionManagement; ValidationOK : Boolean; util : TUser; begin ValidationOK := False; util := GlobalVars.LoggedInUser; // Here i created a local user variable for debug purposes as I thought it would permit me to see the user data. But i get "Inaccessible Value" as its value util.Nom:='test'; for Assoc in util.FonctionManagement do // Here is were my initial " access violation" error occurs begin if Assoc.FonctionManagement.Libelle = 'Reponsable équipe HACCP' then begin ValidationOK := True; break; end; end; [...] end; When I debug I see "Inaccessible Value" in the value column of my user. Do you have any idea why ? I tried to put an integer in this GlobalVar unit, and i was able to set its value from my login form and read it from my other form.. I guess I could store the user's id, which is an integer, and then retrieve the user from the database using its id. But it seems really unefficient.

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• how openjpa2.0 enhances entities at runtime?

  - by Digambar Daund

  Below is my test code: package jee.jpa2; import java.util.List; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.EntityTransaction; import javax.persistence.Persistence; import javax.persistence.Query; import org.testng.annotations.BeforeClass; import org.testng.annotations.Test; @Test public class Tester { EntityManager em; EntityTransaction tx; EntityManagerFactory emf; @BeforeClass public void setup() { emf = Persistence.createEntityManagerFactory("basicPU", System.getProperties()); } @Test public void insert() { Item item = new Item(); for (int i = 0; i < 1000; ++i) { em = emf.createEntityManager(); tx = em.getTransaction(); tx.begin(); item.setId(null); em.persist(item); tx.commit(); em.clear(); em.close(); tx=null; em=null; } } @Test public void read() { em = emf.createEntityManager(); tx = em.getTransaction(); tx.begin(); Query findAll = em.createNamedQuery("findAll"); List<Item> all = findAll.getResultList(); for (Item item : all) { System.out.println(item); } tx.commit(); } } And here is the entity: package jee.jpa2; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.NamedQuery; @Entity @NamedQuery(name="findAll", query="SELECT i FROM Item i") public class Item { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "ID", nullable = false, updatable= false) protected Long id; protected String name; public Item() { name = "Digambar"; } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } @Override public String toString() { return String.format("Item [id=%s, name=%s]", id, name); } } After executing test I get Error: Item [id=1, name=Digambar] Item [id=2, name=Digambar] PASSED: read FAILED: insert <openjpa-2.0.0-r422266:935683 nonfatal store error> org.apache.openjpa.persistence.EntityExistsException: Attempt to persist detached object "jee.jpa2.Item-2". If this is a new instance, make sure any version and/or auto-generated primary key fields are null/default when persisting. FailedObject: jee.jpa2.Item-2 at org.apache.openjpa.kernel.BrokerImpl.persist(BrokerImpl.java:2563) at org.apache.openjpa.kernel.BrokerImpl.persist(BrokerImpl.java:2423) at org.apache.openjpa.kernel.DelegatingBroker.persist(DelegatingBroker.java:1069) at org.apache.openjpa.persistence.EntityManagerImpl.persist(EntityManagerImpl.java:705) at jee.jpa2.Tester.insert(Tester.java:33) Please Explain whats happening here?

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• C#: Inheritence, Overriding, and Hiding

  - by Rosarch

  I'm having difficulty with an architectural decision for my C# XNA game. The basic entity in the world, such as a tree, zombie, or the player, is represented as a GameObject. Each GameObject is composed of at least a GameObjectController, GameObjectModel, and GameObjectView. These three are enough for simple entities, like inanimate trees or rocks. However, as I try to keep the functionality as factored out as possible, the inheritance begins to feel unwieldy. Syntactically, I'm not even sure how best to accomplish my goals. Here is the GameObjectController: public class GameObjectController { protected GameObjectModel model; protected GameObjectView view; public GameObjectController(GameObjectManager gameObjectManager) { this.gameObjectManager = gameObjectManager; model = new GameObjectModel(this); view = new GameObjectView(this); } public GameObjectManager GameObjectManager { get { return gameObjectManager; } } public virtual GameObjectView View { get { return view; } } public virtual GameObjectModel Model { get { return model; } } public virtual void Update(long tick) { } } I want to specify that each subclass of GameObjectController will have accessible at least a GameObjectView and GameObjectModel. If subclasses are fine using those classes, but perhaps are overriding for a more sophisticated Update() method, I don't want them to have to duplicate the code to produce those dependencies. So, the GameObjectController constructor sets those objects up. However, some objects do want to override the model and view. This is where the trouble comes in. Some objects need to fight, so they are CombatantGameObjects: public class CombatantGameObject : GameObjectController { protected new readonly CombatantGameModel model; public new virtual CombatantGameModel Model { get { return model; } } protected readonly CombatEngine combatEngine; public CombatantGameObject(GameObjectManager gameObjectManager, CombatEngine combatEngine) : base(gameObjectManager) { model = new CombatantGameModel(this); this.combatEngine = combatEngine; } public override void Update(long tick) { if (model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); } base.Update(tick); } } Still pretty simple. Is my use of new to hide instance variables correct? Note that I'm assigning CombatantObjectController.model here, even though GameObjectController.Model was already set. And, combatants don't need any special view functionality, so they leave GameObjectController.View alone. Then I get down to the PlayerController, at which a bug is found. public class PlayerController : CombatantGameObject { private readonly IInputReader inputReader; private new readonly PlayerModel model; public new PlayerModel Model { get { return model; } } private float lastInventoryIndexAt; private float lastThrowAt; public PlayerController(GameObjectManager gameObjectManager, IInputReader inputReader, CombatEngine combatEngine) : base(gameObjectManager, combatEngine) { this.inputReader = inputReader; model = new PlayerModel(this); Model.Health = Constants.PLAYER_HEALTH; } public override void Update(long tick) { if (Model.Health <= 0) { gameObjectManager.RemoveFromWorld(this); for (int i = 0; i < 10; i++) { Debug.WriteLine("YOU DEAD SON!!!"); } return; } UpdateFromInput(tick); // .... } } The first time that this line is executed, I get a null reference exception: model.Body.ApplyImpulse(movementImpulse, model.Position); model.Position looks at model.Body, which is null. This is a function that initializes GameObjects before they are deployed into the world: public void Initialize(GameObjectController controller, IDictionary<string, string> data, WorldState worldState) { controller.View.read(data); controller.View.createSpriteAnimations(data, _assets); controller.Model.read(data); SetUpPhysics(controller, worldState, controller.Model.BoundingCircleRadius, Single.Parse(data["x"]), Single.Parse(data["y"]), bool.Parse(data["isBullet"])); } Every object is passed as a GameObjectController. Does that mean that if the object is really a PlayerController, controller.Model will refer to the base's GameObjectModel and not the PlayerController's overriden PlayerObjectModel?

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• Padding error - when using AES Encryption in Java and Decryption in C

  - by user234445

  Hi All, I have a problem while decrypting the xl file in rijndael 'c' code (The file got encrypted in Java through JCE) and this problem is happening only for the excel files types which having formula's. Remaining all file type encryption/decryption is happening properly. (If i decrypt the same file in java the output is coming fine.) While i am dumped a file i can see the difference between java decryption and 'C' file decryption. od -c -b filename(file decrypted in C) 0034620 005 006 \0 \0 \0 \0 022 \0 022 \0 320 004 \0 \0 276 4 005 006 000 000 000 000 022 000 022 000 320 004 000 000 276 064 0034640 \0 \0 \0 \0 \f \f \f \f \f \f \f \f \f \f \f \f 000 000 000 000 014 014 014 014 014 014 014 014 014 014 014 014 0034660 od -c -b filename(file decrypted in Java) 0034620 005 006 \0 \0 \0 \0 022 \0 022 \0 320 004 \0 \0 276 4 005 006 000 000 000 000 022 000 022 000 320 004 000 000 276 064 0034640 \0 \0 \0 \0 000 000 000 000 0034644 (the above is the difference between the dumped files) The following java code i used to encrypt the file. public class AES { /** * Turns array of bytes into string * * @param buf Array of bytes to convert to hex string * @return Generated hex string */ public static void main(String[] args) throws Exception { File file = new File("testxls.xls"); byte[] lContents = new byte[(int) file.length()]; try { FileInputStream fileInputStream = new FileInputStream(file); fileInputStream.read(lContents); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e1) { e1.printStackTrace(); } try { KeyGenerator kgen = KeyGenerator.getInstance("AES"); kgen.init(256); // 192 and 256 bits may not be available // Generate the secret key specs. SecretKey skey = kgen.generateKey(); //byte[] raw = skey.getEncoded(); byte[] raw = "aabbccddeeffgghhaabbccddeeffgghh".getBytes(); SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, skeySpec); byte[] encrypted = cipher.doFinal(lContents); cipher.init(Cipher.DECRYPT_MODE, skeySpec); byte[] original = cipher.doFinal(lContents); FileOutputStream f1 = new FileOutputStream("testxls_java.xls"); f1.write(original); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } I used the following file for decryption in 'C'. #include <stdio.h> #include "rijndael.h" #define KEYBITS 256 #include <stdio.h> #include "rijndael.h" #define KEYBITS 256 int main(int argc, char **argv) { unsigned long rk[RKLENGTH(KEYBITS)]; unsigned char key[KEYLENGTH(KEYBITS)]; int i; int nrounds; char dummy[100] = "aabbccddeeffgghhaabbccddeeffgghh"; char *password; FILE *input,*output; password = dummy; for (i = 0; i < sizeof(key); i++) key[i] = *password != 0 ? *password++ : 0; input = fopen("doc_for_logu.xlsb", "rb"); if (input == NULL) { fputs("File read error", stderr); return 1; } output = fopen("ori_c_res.xlsb","w"); nrounds = rijndaelSetupDecrypt(rk, key, 256); while (1) { unsigned char plaintext[16]; unsigned char ciphertext[16]; int j; if (fread(ciphertext, sizeof(ciphertext), 1, input) != 1) break; rijndaelDecrypt(rk, nrounds, ciphertext, plaintext); fwrite(plaintext, sizeof(plaintext), 1, output); } fclose(input); fclose(output); }

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• PROJECT HELP NEEDED. SOME BASIC CONCEPTS GREAT CONFUSION BECAUSE OF LACK OF PROPER MATERIAL PLEASE H

  - by user287745

  Task ATTENDENCE RECORDER AND MANAGEMENT SYSTEM IN DISTRIBUTED ENVIRONMENT ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Example implementation needed. a main server in each lab where the operator punches in the attendence of the student. =========================================================== scenerio:- a college, 10 departments, all departments have a computer lab with 60-100 computers, the computers within each lab are interconnected and all computers in any department have to dail to a particular number (THE NUMBER GIVEN BY THE COLLEGE INTERNET DEPARTMENT) to get connected to the internet. therefore safe to assume that there is a central location to which all the computers in the college are connected to. there is a 'students attendence portal' which can be accessed using internet explorer, students enter there id and get the particular attendence record regarding to the labs only. a description of the working is like:- 1) the user will select which department, which year has arrived to the lab 2) the selection will give the user a return of all the students name and there roll numbers belonging to that department; 'with a check box to "TICK MARK IF THE STUDENT IS PRESENT" ' 3) A SUBMIT BUTTON when pressed reads the 'id' of the checkbox to determine the "particular count number of the student" from that an id of the student is constructed and that id is inserted with a present. (there is also date and time and much more to normalize the db and to avoid conflicts and keep historic records etc but that you will have to assume) steps taken till this date:- ( please note we are not computer students, we are to select something of some other line as a project!, as you will read in my many post 'i" have designed small websites just out of liking. have never ever done any thing official to implement like this.) * have made the database fully normalized. * have made the website which does the functions required on the database. Testing :- deployed the db and site on a free aspspider server and it worked. tested from several computers. Now the problem please help thank youuuuuuuu a practical demonstration has to be done within the college network. no internet! we have been assigned a lab - 60 computers- to demonstrate. (please dont give replies as 60 computers only! is not a big deal one CPU can manage it. i know that; IT IS A HYPOTHETICAL SITUATION WHERE WE ASSUME THAT 60 IS NOT 60 BUT ITS LIKE 60,000 COMPUTERS) 1a) make a web server, yes iis and put files in www folder and configure server to run aspx files- although a link to a step by step guide will be appreciated)\ ? which version of windows should i ask for xp or win server 2000 something? 2a) make a database server. ( well yes install sql server 2005, okay but then what? just put the database file on a pc share it and append the connection string to the share? ) 3a) make the site accessible from the remaining computers ? http://localhost/sitename ? all users "being operators of the particular lab" have the right to edit, write or delete(in dispute), thereby any "users" who hate our program can make the database inconsistent by accessing te same record and doing different edits and then complaining? so how to prevent this? you know something like when the db table is being written to others can only read but not write.. one big confusion:- IN DISTRIBUTED ENVIRONMENT "how to implement this" where does "distributed environment" come in! meaning :- alright the labs are in different departments but the "database server will be one" the "web server will be one" so whats distributed!?

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• boost::serialization with mutable members

  - by redmoskito

  Using boost::serialization, what's the "best" way to serialize an object that contains cached, derived values in mutable members, such that cached members aren't serialized, but on deserialization, they are initialized the their appropriate default. A definition of "best" follows later, but first an example: class Example { public: Example(float n) : num(n), sqrt_num(-1.0) {} float get_num() const { return num; } // compute and cache sqrt on first read float get_sqrt() const { if(sqrt_num < 0) sqrt_num = sqrt(num); return sqrt_num; } template <class Archive> void serialize(Archive& ar, unsigned int version) { ... } private: float num; mutable float sqrt_num; }; On serialization, only the "num" member should be saved. On deserialization, the sqrt_num member must be initialized to its sentinel value indicating it needs to be computed. What is the most elegant way to implement this? In my mind, an elegant solution would avoid splitting serialize() into separate save() and load() methods (which introduces maintenance problems). One possible implementation of serialize: template <class Archive> void serialize(Archive& ar, unsigned int version) { ar & num; sqrt_num = -1.0; } This handles the deserialization case, but in the serialization case, the cached value is killed and must be recomputed. Also, I've never seen an example of boost::serialize that explicitly sets members inside of serialize(), so I wonder if this is generally not recommended. Some might suggest that the default constructor handles this, for example: int main() { Example e; { std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); ia >> e; } cout << e.get_sqrt() << endl; return 0; } which works in this case, but I think fails if the object receiving the deserialized data has already been initialized, as in the example below: int main() { Example ex1(4); Example ex2(9); cout << ex1.get_sqrt() << endl; // outputs 2; cout << ex2.get_sqrt() << endl; // outputs 3; // the following two blocks should implement ex2 = ex1; // save ex1 to archive { std::ofstream ofs("filename"); boost::archive::text_oarchive oa(ofs); oa << ex1; } // read it back into ex2 { std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); ia >> ex2; } // these should be equal now, but aren't, // since Example::serialize() doesn't modify num_sqrt cout << ex1.get_sqrt() << endl; // outputs 2; cout << ex2.get_sqrt() << endl; // outputs 3; return 0; } I'm sure this issue has come up with others, but I have struggled to find any documentation on this particular scenario. Thanks!

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• C#, AES encryption check!

  - by Data-Base

  I have this code for AES encryption, can some one verify that this code is good and not wrong? it works fine, but I'm more concern about the implementation of the algorithm // Plaintext value to be encrypted. //Passphrase from which a pseudo-random password will be derived. //The derived password will be used to generate the encryption key. //Password can be any string. In this example we assume that this passphrase is an ASCII string. //Salt value used along with passphrase to generate password. //Salt can be any string. In this example we assume that salt is an ASCII string. //HashAlgorithm used to generate password. Allowed values are: "MD5" and "SHA1". //SHA1 hashes are a bit slower, but more secure than MD5 hashes. //PasswordIterations used to generate password. One or two iterations should be enough. //InitialVector (or IV). This value is required to encrypt the first block of plaintext data. //For RijndaelManaged class IV must be exactly 16 ASCII characters long. //KeySize. Allowed values are: 128, 192, and 256. //Longer keys are more secure than shorter keys. //Encrypted value formatted as a base64-encoded string. public static string Encrypt(string PlainText, string Password, string Salt, string HashAlgorithm, int PasswordIterations, string InitialVector, int KeySize) { byte[] InitialVectorBytes = Encoding.ASCII.GetBytes(InitialVector); byte[] SaltValueBytes = Encoding.ASCII.GetBytes(Salt); byte[] PlainTextBytes = Encoding.UTF8.GetBytes(PlainText); PasswordDeriveBytes DerivedPassword = new PasswordDeriveBytes(Password, SaltValueBytes, HashAlgorithm, PasswordIterations); byte[] KeyBytes = DerivedPassword.GetBytes(KeySize / 8); RijndaelManaged SymmetricKey = new RijndaelManaged(); SymmetricKey.Mode = CipherMode.CBC; ICryptoTransform Encryptor = SymmetricKey.CreateEncryptor(KeyBytes, InitialVectorBytes); MemoryStream MemStream = new MemoryStream(); CryptoStream CryptoStream = new CryptoStream(MemStream, Encryptor, CryptoStreamMode.Write); CryptoStream.Write(PlainTextBytes, 0, PlainTextBytes.Length); CryptoStream.FlushFinalBlock(); byte[] CipherTextBytes = MemStream.ToArray(); MemStream.Close(); CryptoStream.Close(); return Convert.ToBase64String(CipherTextBytes); } public static string Decrypt(string CipherText, string Password, string Salt, string HashAlgorithm, int PasswordIterations, string InitialVector, int KeySize) { byte[] InitialVectorBytes = Encoding.ASCII.GetBytes(InitialVector); byte[] SaltValueBytes = Encoding.ASCII.GetBytes(Salt); byte[] CipherTextBytes = Convert.FromBase64String(CipherText); PasswordDeriveBytes DerivedPassword = new PasswordDeriveBytes(Password, SaltValueBytes, HashAlgorithm, PasswordIterations); byte[] KeyBytes = DerivedPassword.GetBytes(KeySize / 8); RijndaelManaged SymmetricKey = new RijndaelManaged(); SymmetricKey.Mode = CipherMode.CBC; ICryptoTransform Decryptor = SymmetricKey.CreateDecryptor(KeyBytes, InitialVectorBytes); MemoryStream MemStream = new MemoryStream(CipherTextBytes); CryptoStream cryptoStream = new CryptoStream(MemStream, Decryptor, CryptoStreamMode.Read); byte[] PlainTextBytes = new byte[CipherTextBytes.Length]; int ByteCount = cryptoStream.Read(PlainTextBytes, 0, PlainTextBytes.Length); MemStream.Close(); cryptoStream.Close(); return Encoding.UTF8.GetString(PlainTextBytes, 0, ByteCount); } Thank you

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• How to sanely configure security policy in Tomcat 6

  - by Chas Emerick

  I'm using Tomcat 6.0.24, as packaged for Ubuntu Karmic. The default security policy of Ubuntu's Tomcat package is pretty stringent, but appears straightforward. In /var/lib/tomcat6/conf/policy.d, there are a variety of files that establish default policy. Worth noting at the start: I've not changed the stock tomcat install at all -- no new jars into its common lib directory(ies), no server.xml changes, etc. Putting the .war file in the webapps directory is the only deployment action. the web application I'm deploying fails with thousands of access denials under this default policy (as reported to the log thanks to the -Djava.security.debug="access,stack,failure" system property). turning off the security manager entirely results in no errors whatsoever, and proper app functionality What I'd like to do is add an application-specific security policy file to the policy.d directory, which seems to be the recommended practice. I added this to policy.d/100myapp.policy (as a starting point -- I would like to eventually trim back the granted permissions to only what the app actually needs): grant codeBase "file:${catalina.base}/webapps/ROOT.war" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/-" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/WEB-INF/-" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/WEB-INF/lib/-" { permission java.security.AllPermission; }; grant codeBase "file:${catalina.base}/webapps/ROOT/WEB-INF/classes/-" { permission java.security.AllPermission; }; Note the thrashing around attempting to find the right codeBase declaration. I think that's likely my fundamental problem. Anyway, the above (really only the first two grants appear to have any effect) almost works: the thousands of access denials are gone, and I'm left with just one. Relevant stack trace: java.security.AccessControlException: access denied (java.io.FilePermission /var/lib/tomcat6/webapps/ROOT/WEB-INF/classes/com/foo/some-file-here.txt read) java.security.AccessControlContext.checkPermission(AccessControlContext.java:323) java.security.AccessController.checkPermission(AccessController.java:546) java.lang.SecurityManager.checkPermission(SecurityManager.java:532) java.lang.SecurityManager.checkRead(SecurityManager.java:871) java.io.File.exists(File.java:731) org.apache.naming.resources.FileDirContext.file(FileDirContext.java:785) org.apache.naming.resources.FileDirContext.lookup(FileDirContext.java:206) org.apache.naming.resources.ProxyDirContext.lookup(ProxyDirContext.java:299) org.apache.catalina.loader.WebappClassLoader.findResourceInternal(WebappClassLoader.java:1937) org.apache.catalina.loader.WebappClassLoader.findResource(WebappClassLoader.java:973) org.apache.catalina.loader.WebappClassLoader.getResource(WebappClassLoader.java:1108) java.lang.ClassLoader.getResource(ClassLoader.java:973) I'm pretty convinced that the actual file that's triggering the denial is irrelevant -- it's just some properties file that we check for optional configuration parameters. What's interesting is that: it doesn't exist in this context the fact that the file doesn't exist ends up throwing a security exception, rather than java.io.File.exists() simply returning false (although I suppose that's just a matter of the semantics of the read permission). Another workaround (besides just disabling the security manager in tomcat) is to add an open-ended permission to my policy file: grant { permission java.security.AllPermission; }; I presume this is functionally equivalent to turning off the security manager. I suppose I must be getting the codeBase declaration in my grants subtly wrong, but I'm not seeing it at the moment.

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• Technology to communicate with someone with expressive aphasia?

  - by rascher

  A family member had a stroke a few years back and now has expressive aphasia. She understands what is said to her, is cognitive of what is going on, but cannot express herself. She is able to respond to yes/no questions (do you want to go shopping? are you looking for your earrings?) She is not, however, able to read (English is not her native language and she hasn't read Hindi for decades.) I am the technologist in the family, and I intend to come up with something to help us communicate. The idea is to have some sort of picture book where she can point to what she wants. My first question: does some sort of assistive technology for people with expressive aphasia already exist? These can be hardware or software devices? If not, then such a software doesn't seem difficult to write. My initial thought is to have an interface with pictures - maybe separated by category (food, shopping) - where she can point to an individual picture to indicate what she needs. We could easily add more items with such a software, and we could have an interface where she (or we) could "flip pages". Which suggests that the best solution would use a touch screen rather than a mouse. It would be really difficult to train her to aim a mouse or find keys on a keyboard. We're thinking of maybe getting a tablet and writing some basic software. But tablets computers are expensive and fragile - I'm not sure if it would be able to stand spills or being knocked about in a nursing home. So my next question: what kind of tablet-like devices are out there which I can program on? I don't know anything about hardware, but if there is something then we could special-order it. What would be safe and durable for such a project? We could do something on an iPod or cell phone, but I feel like that interface would be too small. Finally, does anyone here have experience with this kind of assistive technology? Things I might not anticipate when designing such a system? edit I've added a (pretty hefty!) bounty. I'd kinda like to open this question up to any suggestions, comments, and experiences that people might have. This is a pretty real and important project, so while we will (are working on) a solution, any insights would be particularly helpful. Right now the plan is to mount a screen in her room. We'll either teach her to use a trackball or use a touch-screen panel, after seeing what she is able to use with a simple prototype. Then software akin to an old "hypercard" deck: ---------------------------------------------------------------- | -------------- -------------- | | | Clothes | | Food | ... | | -------------- -------------- | | | | Pic of item 1 Pic of item 2 Pic of item 3 | | | | | | | | | | Pic of item 4 Pic of item 5 Pic of item 6 | | | | | | | | | | <-Back Next-> | ---------------------------------------------------------------- commentcommentcomment!

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• Is the Unix Philosophy still relevant in the Web 2.0 world?

  - by David Titarenco

  Introduction Hello, let me give you some background before I begin. I started programming when I was 5 or 6 on my dad's PSION II (some primitive BASIC-like language), then I learned more and more, eventually inching my way up to C, C++, Java, PHP, JS, etc. I think I'm a pretty decent coder. I think most people would agree. I'm not a complete social recluse, but I do stuff like write a virtual machine for fun. I've never taken a computer course in college because I've been in and out for the past couple of years and have only been taking core classes; never having been particularly amazing at school, perhaps I'm missing some basic tenet that most learn in CS101. I'm currently reading Coders at Work and this question is based on some ideas I read in there. A Brief (Fictionalized) Example So a certain sunny day I get an idea. I hire a designer and hammer away at some C/C++ code for a couple of months, soon thereafter releasing silvr.com, a website that transmutes lead into silver. Yep, I started my very own start-up and even gave it a clever web 2.0 name with a vowel missing. Mom and dad are proud. I come up with some numbers I should be seeing after 1, 2, 3, 6, 9, 12 months and set sail. Obviously, my transmuting server isn't perfect, sometimes it segfaults, sometimes it leaks memory. I fix it and keep truckin'. After all, gdb is my best friend. Eventually, I'm at a position where a very small community of people are happily transmuting lead into silver on a semi-regular basis, but they want to let their friends on MySpace know how many grams of lead they transmuted today. And they want to post images of their lead and silver nuggets on flickr. I'm losing out on potential traffic unless I let them log in with their Yahoo, Google, and Facebook accounts. They want webcam support and live cock fighting, merry-go-rounds and Jabberwockies. All these things seem necessary. The Aftermath Of course, I have to re-write the transmuting server! After all, I've been losing money all these months. I need OAuth libraries and OpenID libraries, JSON support, and the only stable Jabberwocky API is for Java. C++ isn't even an option anymore. I'm just one guy! The Java binary just grows and grows since I need some legacy Apache include for the JSON library, and some antiquated Sun dependency for OAuth support. Then I pick up a book like Coders at Work and read what people like jwz say about complexity... I think to myself.. Keep it simple, stupid. I like simple things. I've always loved the Unix Philosophy but even after trying to keep the new server source modular and sleek, I loathe having to write one more line of code. It feels that I'm just piling crap on top of other crap. Maybe I'm naive thinking every piece of software can be simple and clever. Maybe it's just a phase.. or is the Unix Philosophy basically dead when it comes to the current state of (web) development? I'm just kind of disheartened :(

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• calling concurrently Graphics.Draw and new Bitmap from memory in thread take long time

  - by Abdul jalil

  Example1 public partial class Form1 : Form { public Form1() { InitializeComponent(); pro = new Thread(new ThreadStart(Producer)); con = new Thread(new ThreadStart(Consumer)); } private AutoResetEvent m_DataAvailableEvent = new AutoResetEvent(false); Queue<Bitmap> queue = new Queue<Bitmap>(); Thread pro; Thread con ; public void Producer() { MemoryStream[] ms = new MemoryStream[3]; for (int y = 0; y < 3; y++) { StreamReader reader = new StreamReader("image"+(y+1)+".JPG"); BinaryReader breader = new BinaryReader(reader.BaseStream); byte[] buffer=new byte[reader.BaseStream.Length]; breader.Read(buffer,0,buffer.Length); ms[y] = new MemoryStream(buffer); } while (true) { for (int x = 0; x < 3; x++) { Bitmap bmp = new Bitmap(ms[x]); queue.Enqueue(bmp); m_DataAvailableEvent.Set(); Thread.Sleep(6); } } } public void Consumer() { Graphics g= pictureBox1.CreateGraphics(); while (true) { m_DataAvailableEvent.WaitOne(); Bitmap bmp = queue.Dequeue(); if (bmp != null) { // Bitmap bmp = new Bitmap(ms); g.DrawImage(bmp,new Point(0,0)); bmp.Dispose(); } } } private void pictureBox1_Click(object sender, EventArgs e) { con.Start(); pro.Start(); } } when Creating bitmap and Drawing to picture box are in seperate thread then Bitmap bmp = new Bitmap(ms[x]) take 45.591 millisecond and g.DrawImage(bmp,new Point(0,0)) take 41.430 milisecond when i make bitmap from memoryStream and draw it to picture box in one thread then Bitmap bmp = new Bitmap(ms[x]) take 29.619 and g.DrawImage(bmp,new Point(0,0)) take 35.540 the code is for Example 2 is why it take more time to draw and bitmap take time in seperate thread and how to reduce the time when processing in seperate thread. i am using ANTS performance profiler 4.3 public Form1() { InitializeComponent(); pro = new Thread(new ThreadStart(Producer)); con = new Thread(new ThreadStart(Consumer)); } private AutoResetEvent m_DataAvailableEvent = new AutoResetEvent(false); Queue<MemoryStream> queue = new Queue<MemoryStream>(); Thread pro; Thread con ; public void Producer() { MemoryStream[] ms = new MemoryStream[3]; for (int y = 0; y < 3; y++) { StreamReader reader = new StreamReader("image"+(y+1)+".JPG"); BinaryReader breader = new BinaryReader(reader.BaseStream); byte[] buffer=new byte[reader.BaseStream.Length]; breader.Read(buffer,0,buffer.Length); ms[y] = new MemoryStream(buffer); } while (true) { for (int x = 0; x < 3; x++) { // Bitmap bmp = new Bitmap(ms[x]); queue.Enqueue(ms[x]); m_DataAvailableEvent.Set(); Thread.Sleep(6); } } } public void Consumer() { Graphics g= pictureBox1.CreateGraphics(); while (true) { m_DataAvailableEvent.WaitOne(); //Bitmap bmp = queue.Dequeue(); MemoryStream ms= queue.Dequeue(); if (ms != null) { Bitmap bmp = new Bitmap(ms); g.DrawImage(bmp,new Point(0,0)); bmp.Dispose(); } } } private void pictureBox1_Click(object sender, EventArgs e) { con.Start(); pro.Start(); }

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• Writing a code example

  - by Stefano Borini

  I would like to have your feedback regarding code examples. One of the most frustrating experiences I sometimes have when learning a new technology is finding useless examples. I think an example as the most precious thing that comes with a new library, language, or technology. It must be a starting point, a wise and unadulterated explanation on how to achieve a given result. A perfect example must have the following characteristics: Self contained: it should be small enough to be compiled or executed as a single program, without dependencies or complex makefiles. An example is also a strong functional test if you correctly installed the new technology. The more issues could arise, the more likely is that something goes wrong, and the more difficult is to debug and solve the situation. Pertinent: it should demonstrate one, and only one, specific feature of your software/library, involving the minimal additional behavior from external libraries. Helpful: the code should bring you forward, step by step, using comments or self-documenting code. Extensible: the example code should be a small “framework” or blueprint for additional tinkering. A learner can start by adding features to this blueprint. Recyclable: it should be possible to extract parts of the example to use in your own code Easy: An example code is not the place to show your code-fu skillz. Keep it easy. helpful acronym: SPHERE. Prototypical examples of violations of those rules are the following: Violation of self-containedness: an example spanning multiple files without any real need for it. If your example is a python program, keep everything into a single module file. Don’t sub-modularize it. In Java, try to keep everything into a single class, unless you really must partition some entity into a meaningful object you need to pass around (and java mandates one class per file, if I remember correctly). Violation of Pertinency: When showing how many different shapes you can draw, adding radio buttons and complex controls with all the possible choices for point shapes is a bad idea. You de-focalize your example code, introducing code for event handling, controls initialization etc., and this is not part the feature you want to demonstrate, they are unnecessary noise in the understanding of the crucial mechanisms providing the feature. Violation of Helpfulness: code containing dubious naming, wrong comments, hacks, and functions longer than one page of code. Violation of Extensibility: badly factored code that have everything into a single function, with potentially swappable entities embedded within the code. Example: if an example reads data from a file and displays it, create a method getData() returning a useful entity, instead of opening the file raw and plotting the stuff. This way, if the user of the library needs to read data from a HTTP server instead, he just has to modify the getData() module and use the example almost as-is. Another violation of Extensibility comes if the example code is not under a fully liberal (e.g. MIT or BSD) license. Violation of Recyclability: when the code layout is so intermingled that is difficult to easily copy and paste parts of it and recycle them into another program. Again, licensing is also a factor. Violation of Easiness: Yes, you are a functional-programming nerd and want to show how cool you are by doing everything on a single line of map, filter and so on, but that could not be helpful to someone else, who is already under pressure to understand your library, and now has to understand your code as well. And in general, the final rule: if it takes more than 10 minutes to do the following: compile the code, run it, read the source, and understand it fully, it means that the example is not a good one. Please let me know your opinion, either positive or negative, or experience on this regard.

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• Problem with memset after an instance of a user defined class is created and a file is opened

  - by Liberalkid

  I'm having a weird problem with memset, that was something to do with a class I'm creating before it and a file I'm opening in the constructor. The class I'm working with normally reads in an array and transforms it into another array, but that's not important. The class I'm working with is: #include <vector> #include <algorithm> using namespace std; class PreProcess { public: PreProcess(char* fileName,char* outFileName); void SortedOrder(); private: vector< vector<double > > matrix; void SortRow(vector<double> &row); char* newFileName; vector< pair<double,int> > rowSorted; }; The other functions aren't important, because I've stopped calling them and the problem persists. Essentially I've narrowed it down to my constructor: PreProcess::PreProcess(char* fileName,char* outFileName):newFileName(outFileName){ ifstream input(fileName); input.close(); //this statement is inconsequential } I also read in the file in my constructor, but I've found that the problem persists if I don't read in the matrix and just open the file. Essentially I've narrowed it down to if I comment out those two lines the memset works properly, otherwise it doesn't. Now to the context of the problem I'm having with it: I wrote my own simple wrapper class for matrices. It doesn't have much functionality, I just need 2D arrays in the next part of my project and having a class handle everything makes more sense to me. The header file: #include <iostream> using namespace std; class Matrix{ public: Matrix(int r,int c); int &operator()(int i,int j) {//I know I should check my bounds here return matrix[i*columns+j]; } ~Matrix(); const void Display(); private: int *matrix; const int rows; const int columns; }; Driver: #include "Matrix.h" #include <string> using namespace std; Matrix::Matrix(int r,int c):rows(r),columns(c) { matrix=new int[rows*columns]; memset(matrix,0,sizeof(matrix)); } const void Matrix::Display(){ for(int i=0;i<rows;i++){ for(int j=0;j<columns;j++) cout << (*this)(i,j) << " "; cout << endl; } } Matrix::~Matrix() { delete matrix; } My main program runs: PreProcess test1(argv[1],argv[2]); //test1.SortedOrder(); Matrix test(10,10); test.Display(); And when I run this with the input line uncommented I get: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1371727776 32698 -1 0 0 0 0 0 6332656 0 -1 -1 0 0 6332672 0 0 0 0 0 0 0 0 0 0 0 0 0 -1371732704 32698 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 I really don't have a clue what's going on in memory to cause this, on a side note if I replace memset with: for(int i=0;i<rows*columns;i++) *(matrix+i) &= 0x0; Then it works perfectly, it also works if I don't open the file. If it helps I'm running GCC 64-bit version 4.2.4 on Ubuntu.I assume there's some functionality of memset that I'm not properly understanding.

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• Why does File::Slurp return a scalar when it should return a list?

  - by BrianH

  I am new to the File::Slurp module, and on my first test with it, it was not giving the results I was expecting. It took me a while to figure it out, so now I am interested in why I was seeing this certain behavior. My call to File::Slurp looked like this: my @array = read_file( $file ) || die "Cannot read $file\n"; I included the "die" part because I am used to doing that when opening files. My @array would always end up with the entire contents of the file in the first element of the array. Finally I took out the "|| die" section, and it started working as I expected. Here is an example to illustrate: perl -de0 Loading DB routines from perl5db.pl version 1.22 Editor support available. Enter h or `h h' for help, or `man perldebug' for more help. main::(-e:1): 0 DB<1> use File::Slurp DB<2> $file = '/usr/java6_64/copyright' DB<3> x @array1 = read_file( $file ) 0 'Licensed material - Property of IBM.' 1 'IBM(R) SDK, Java(TM) Technology Edition, Version 6' 2 'IBM(R) Runtime Environment, Java(TM) Technology Edition, Version 6' 3 '' 4 'Copyright Sun Microsystems Inc, 1992, 2008. All rights reserved.' 5 'Copyright IBM Corporation, 1998, 2009. All rights reserved.' 6 '' 7 'The Apache Software License, Version 1.1 and Version 2.0' 8 'Copyright 1999-2007 The Apache Software Foundation. All rights reserved.' 9 '' 10 'Other copyright acknowledgements can be found in the Notices file.' 11 '' 12 'The Java technology is owned and exclusively licensed by Sun Microsystems Inc.' 13 'Java and all Java-based trademarks and logos are trademarks or registered' 14 'trademarks of Sun Microsystems Inc. in the United States and other countries.' 15 '' 16 'US Govt Users Restricted Rights - Use duplication or disclosure' 17 'restricted by GSA ADP Schedule Contract with IBM Corp.' DB<4> x @array2 = read_file( $file ) || die "Cannot read $file\n"; 0 'Licensed material - Property of IBM. IBM(R) SDK, Java(TM) Technology Edition, Version 6 IBM(R) Runtime Environment, Java(TM) Technology Edition, Version 6 Copyright Sun Microsystems Inc, 1992, 2008. All rights reserved. Copyright IBM Corporation, 1998, 2009. All rights reserved. The Apache Software License, Version 1.1 and Version 2.0 Copyright 1999-2007 The Apache Software Foundation. All rights reserved. Other copyright acknowledgements can be found in the Notices file. The Java technology is owned and exclusively licensed by Sun Microsystems Inc. Java and all Java-based trademarks and logos are trademarks or registered trademarks of Sun Microsystems Inc. in the United States and other countries. US Govt Users Restricted Rights - Use duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. ' Why does the || die make a difference? I have a feeling this might be more of a Perl precedence question instead of a File::Slurp question. I looked in the File::Slurp module and it looks like it is set to croak if there is a problem, so I guess the proper way to do it is to allow File::Slurp to croak for you. Now I'm just curious why I was seeing these differences.

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• PHP: How do I loop through every XML file in a directory?

  - by celebritarian

  Hi! I'm building a simple application. It's a user interface to an online order system. Basically, the system is going to work like this: Other companies upload their purchase orders to our FTP server. These orders are simple XML files (containing things like customer data, address information, ordered products and the quantities…) I've built a simple user interface in HTML5, jQuery and CSS — all powered by PHP. PHP reads the content of an order (using the built-in features of SimpleXML) and displays it on the web page. So, it's a web app, supposed to always be running in a browser at the office. The PHP app will display the content of all orders. Every fifteen minutes or so, the app will check for new orders. How do I loop through all XML files in a directory? Right now, my app is able to read the content of a single XML file, and display it in a nice way on the page. My current code looks like this: // pick a random order that I know exists in the Order directory: $xml_file = file_get_contents("Order/6366246.xml",FILE_TEXT); $xml = new SimpleXMLElement($xml_file); // start echo basic order information, like order number: echo $xml->OrderHead->ShopPO; // more information about the order and the customer goes here… echo "<ul>"; // loop through each order line, and echo all quantities and products: foreach ($xml->OrderLines->OrderLine as $orderline) { echo "<tr>\n". "<li>".$orderline->Quantity." st.</li>\n". "<li>".$orderline->SKU."</li>\n"; } echo "</ul>"; // more information about delivery options, address information etc. goes here… So, that's my code. Pretty simple. It only needs to do one thing — print out the content of all order files on the screen — so me and my colleagues can see the order, confirm it and deliver it. That's it. But right now — as you can see — I'm selecting one single order at a time, located in the Order directory. But how do I loop through the entire Order directory, and read aand display the content of each order (like above)? I'm stuck. I don't really know how you get all (xml) files in a directory and then do something with the files (like reading them and echo out the data, like I want to). -- I'd really appreciate some help. I'm not very experienced with PHP/server-side programming, so if you could help me out here I'd be very grateful. Thanks a lot in advance! // Björn (celebritarian at me dot com)

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• Database connection timeout

  - by Clinton Bosch

  Hi I have read so many articles on the Internet about this problem but none seem to have a clear solution. Please could someone give me a definite answer as to why I am getting database timeouts. The app is a GWT app that is being hosted on a Tomcat 5.5 server. I use spring and the session factory is created in the applicationContext.xml as follows <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">${connection.dialect}</prop> <prop key="hibernate.connection.username">${connection.username}</prop> <prop key="hibernate.connection.password">${connection.password}</prop> <prop key="hibernate.connection.url">${connection.url}</prop> <prop key="hibernate.connection.driver_class">${connection.driver.class}</prop> <prop key="hibernate.show_sql">${show.sql}</prop> <prop key="hibernate.hbm2ddl.auto">update</prop> <prop key="hibernate.c3p0.min_size">5</prop> <prop key="hibernate.c3p0.max_size">20</prop> <prop key="hibernate.c3p0.timeout">1800</prop> <prop key="hibernate.c3p0.max_statements">50</prop> <prop key="hibernate.c3p0.idle_test_period">300</prop> </props> </property> <property name="annotatedClasses"> <list> <value>za.co.xxxx.traintrack.server.model.Answer</value> <value>za.co.xxxx.traintrack.server.model.Company</value> <value>za.co.xxxx.traintrack.server.model.CompanyRegion</value> <value>za.co.xxxx.traintrack.server.model.Merchant</value> <value>za.co.xxxx.traintrack.server.model.Module</value> <value>za.co.xxxx.traintrack.server.model.Question</value> <value>za.co.xxxx.traintrack.server.model.User</value> <value>za.co.xxxx.traintrack.server.model.CompletedModule</value> </list> </property> </bean> <bean id="dao" class="za.co.xxxx.traintrack.server.DAO"> <property name="sessionFactory" ref="sessionFactory"/> <property name="adminUsername" value="${admin.user.name}"/> <property name="adminPassword" value="${admin.user.password}"/> <property name="godUsername" value="${god.user.name}"/> <property name="godPassword" value="${god.user.password}"/> </bean> All works fine untile the next day: INFO | jvm 1 | 2010/06/15 14:42:27 | 2010-06-15 18:42:27,804 WARN [JDBCExceptionReporter] : SQL Error: 0, SQLState: 08S01 INFO | jvm 1 | 2010/06/15 14:42:27 | 2010-06-15 18:42:27,821 ERROR [JDBCExceptionReporter] : The last packet successfully received from the server was 38729 seconds ago.The last packet sent successfully to the server was 38729 seconds ago, which is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem. INFO | jvm 1 | 2010/06/15 14:42:27 | Jun 15, 2010 6:42:27 PM org.apache.catalina.core.ApplicationContext log INFO | jvm 1 | 2010/06/15 14:42:27 | SEVERE: Exception while dispatching incoming RPC call I have read so many different things (none of which worked), please help

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