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  • Access is denied while moving a file from different volumes

    - by logeeks
    i have a portable 500GB HDD plugged into my dell xps system. The system have windows 7 professional edition. the problem is that when i try to open a file(visual studio .sln file) it is saying that access is denied. I cannot copy this file to a different location(within my local HDD) it is saying that i need permission for the task to complete. I've checked and confirmed the following things 1) I've logged into an admin account before attempting these operations 2) My admin account have 'Full Control' 3) I've full control over the portable HDD 4) I changed the 'UAC' settings to 'Never notify' Please help.

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  • Building new GIS Workstation - is it worth upgrading to a workstation GPU?

    - by bsigrist
    We are currently building a machine from scratch to act as a GIS workstation. The primary software used is ESRI's ArcGIS and we are mainly working with vector data using raster data only for contextual background imagery. In the past I have built a GIS machine and used a consumer grade gaming GPU (Nvidia 9800GT) and found it to perform fine. However, I have always wondered if I would have been better off equipping it with a workstation GPU such as a Quadro series. Would a workstation GPU make a noticeable difference doing 2D GIS operations or should I save money on the build and equip it with another 9800GT?

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  • Best PerfCounters for monitoring system health of IIS, WCF, WWF and .Net for a Workflow based soluti

    - by Gineer
    We have a solution built in .Net that will be installed into a client environment. The solution will span multiple servers and be running on multiple tiers. The client makes us of MOM (Microsoft operations Manager) to monitor the system. What are the best counters to use for monitoring the overall health of the system? Are there any built in counters that we could add into a MOM Pack (as an Alert) to test a given scenario? Any thoughts suggestions would be much apreciated. Thanks

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  • 3-way quicksort, question

    - by peiska
    I am trying to understand the 3-way radix Quicksort, and i dont understand why the the CUTOFF variable there? and the insertion method? public class Quick3string { private static final int CUTOFF = 15; // cutoff to insertion sort // sort the array a[] of strings public static void sort(String[] a) { // StdRandom.shuffle(a); sort(a, 0, a.length-1, 0); assert isSorted(a); } // return the dth character of s, -1 if d = length of s private static int charAt(String s, int d) { assert d >= 0 && d <= s.length(); if (d == s.length()) return -1; return s.charAt(d); } // 3-way string quicksort a[lo..hi] starting at dth character private static void sort(String[] a, int lo, int hi, int d) { // cutoff to insertion sort for small subarrays if (hi <= lo + CUTOFF) { insertion(a, lo, hi, d); return; } int lt = lo, gt = hi; int v = charAt(a[lo], d); int i = lo + 1; while (i <= gt) { int t = charAt(a[i], d); if (t < v) exch(a, lt++, i++); else if (t > v) exch(a, i, gt--); else i++; } // a[lo..lt-1] < v = a[lt..gt] < a[gt+1..hi]. sort(a, lo, lt-1, d); if (v >= 0) sort(a, lt, gt, d+1); sort(a, gt+1, hi, d); } // sort from a[lo] to a[hi], starting at the dth character private static void insertion(String[] a, int lo, int hi, int d) { for (int i = lo; i <= hi; i++) for (int j = i; j > lo && less(a[j], a[j-1], d); j--) exch(a, j, j-1); } // exchange a[i] and a[j] private static void exch(String[] a, int i, int j) { String temp = a[i]; a[i] = a[j]; a[j] = temp; } // is v less than w, starting at character d private static boolean less(String v, String w, int d) { assert v.substring(0, d).equals(w.substring(0, d)); return v.substring(d).compareTo(w.substring(d)) < 0; } // is the array sorted private static boolean isSorted(String[] a) { for (int i = 1; i < a.length; i++) if (a[i].compareTo(a[i-1]) < 0) return false; return true; } public static void main(String[] args) { // read in the strings from standard input String[] a = StdIn.readAll().split("\\s+"); int N = a.length; // sort the strings sort(a); // print the results for (int i = 0; i < N; i++) StdOut.println(a[i]); } } from http://www.cs.princeton.edu/algs4/51radix/Quick3string.java.html

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  • Permission forbidden on localhost with apache2

    - by N Alex
    Here is what I am trying to do. I tried to add another folder to apache and I get the following error when trying to acces testing/index.html. The idea is that I would like to have for every customer a folder like /home/neagoe/Work/InterWebs/Projects/[PROJECT NAME]/CustomerProjects/website/dist. Forbidden You don't have permission to access /index.html on this server. Apache/2.2.22 (Ubuntu) Server at testing Port 80 Here are the steps that I followed: Step1: sudo chmod a+x /home/neagoe/Work/InterWebs/Projects/testing/CustomerProjects/website/dist Step2: sudo chown -R www-data:www-data /home/neagoe/Work/InterWebs/Projects/testing/CustomerProjects/website/dist sudo chmod -R 775 /home/neagoe/Work/InterWebs/Projects/testing/CustomerProjects/website/dist Step3: sudo adduser $USER www-data Step4: sudo a2enmod userdir Step5: sudo cp /etc/apache/sites-available/default /etc/apache/sites-available/testing I edited the file /etc/apache/sites-available/testing so it looks like this: <VirtualHost *:80> ServerAdmin webmaster@localhost ServerName testing DocumentRoot /home/neagoe/Work/InterWebs/Projects/testing/CustomerProjects/website/dist <Directory /> Options FollowSymLinks AllowOverride None </Directory> <Directory /home/neagoe/Work/InterWebs/Projects/testing/CustomerProjects/website/dist/ > Options Indexes FollowSymLinks MultiViews AllowOverride All Order allow,deny allow from all </Directory> ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/ <Directory "/usr/lib/cgi-bin"> AllowOverride None Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch Order allow,deny Allow from all </Directory> ErrorLog ${APACHE_LOG_DIR}/error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog ${APACHE_LOG_DIR}/access.log combined </VirtualHost> Step6: I edited hosts ("/etc/hosts") so it looks like this: 127.0.0.1 localhost 127.0.0.1 testing # The following lines are desirable for IPv6 capable hosts ::1 ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters Step7: sudo a2ensite testing sudo service apache2 restart I searched for about 2 hours on the internet but I can't figure out what went wrong. All the pages that I found following the same steps as described above. I know there are similar questions here on the internet, but the answer is to change permission to the directory which I did on Step2. I am sorry if this is really a duplicate but I could't find the right answer. Thank you! PS. I asked this also on AskUbuntu but didn't get any answers so I'm trying my luck here. Edit: There isn't much on the error log or the access log. On the access.log: ::1 - - [10/Aug/2013:11:23:28 +0300] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)" ::1 - - [10/Aug/2013:11:23:29 +0300] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)" ::1 - - [10/Aug/2013:11:23:31 +0300] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)" ::1 - - [10/Aug/2013:11:23:32 +0300] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)" ::1 - - [10/Aug/2013:11:23:33 +0300] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)" ::1 - - [10/Aug/2013:11:23:34 +0300] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)" ::1 - - [10/Aug/2013:11:23:35 +0300] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)" 127.0.0.1 - - [10/Aug/2013:11:23:23 +0300] "POST /wordpress-testing/wp-cron.php?doing_wp_cron=1376123003.7026669979095458984375 HTTP/1.0" 200 705 "-" "WordPress/3.6; http://localhost/wordpress-testing" ::1 - - [10/Aug/2013:11:23:36 +0300] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)" ::1 - - [10/Aug/2013:11:23:37 +0300] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)" ::1 - - [10/Aug/2013:11:23:38 +0300] "OPTIONS * HTTP/1.0" 200 126 "-" "Apache/2.2.22 (Ubuntu) (internal dummy connection)" 127.0.0.1 - - [10/Aug/2013:11:31:32 +0300] "GET /index.html HTTP/1.1" 200 485 "-" "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:23.0) Gecko/20100101 Firefox/23.0" And the last line repeats for about 200 rows. On the error.log: 1. This lines repeat from time to time. PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php5/20100525 /msql.so' - /usr/lib/php5/20100525/msql.so: cannot open shared object file: No such file or directory in Unknown on line 0 [Sat Aug 10 13:06:42 2013] [notice] Apache/2.2.22 (Ubuntu) PHP/5.4.9-4ubuntu2.2 configured -- resuming normal operations [Sat Aug 10 13:07:36 2013] [notice] caught SIGTERM, shutting down PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php5/20100525/msql.so' - /usr/lib/php5/20100525/msql.so: cannot open shared object file: No such file or directory in Unknown on line 0 [Sat Aug 10 13:07:37 2013] [notice] Apache/2.2.22 (Ubuntu) PHP/5.4.9-4ubuntu2.2 configured -- resuming normal operations 2. And this is the predominant error. (hundreds of lines) [Sat Aug 10 13:07:40 2013] [error] [client 127.0.0.1] (13)Permission denied: access to /index.html denied

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  • Simplest way to expose UNIX mailboxes via IMAP or POP3 on RHEL 5.6

    - by db2
    We've got a web server running RedHat Enterprise Linux 5.6, and it has all the usual local UNIX mailboxes. As is typical, the root mailbox gets all the cron output, logwatch results, etc. I'd like an easier way to keep an eye on this mailbox besides running mail via ssh. What should I install/enable to allow access to these system mailboxes via IMAP or POP3 with minimal fuss? Either protocol would be fine for what I'm doing, as I could then add it as an account in Outlook. A bit of searching led me to cyrus-imapd and dovecot, but it seems like they are meant for more serious mail hosting operations. Either they use their own mailbox system exclusively, or don't have a simple way of making the UNIX mailboxes available. If I'm wrong about that, then I'm fine with using either of them as long as I can get to the mailboxes of the existing accounts on the box.

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  • how can I git-revise configs in my /etc/ dir? (sudo has different keys..)

    - by Dean Rather
    I'd like to keep some of the folders in my /etc/ dir git-revised, cause I'm quite new to server administration and am constantly messing around in my /etc/nginx/ and /etc/bind/ directories. I've heard of people git-revising their either /etc/ directories, but that seems a bit like overkill, as at this point I'm only messing in those 2 subdirectories. The problem I'm having is that if I sudo my git operations, I don't have the right pubkeys to push to my remote repo (bitbucket). But if I don't sudo, I need to mess around with all the permissions (again, not very pro at this). Does anyone know best practices for managing their configs? or how I should solve this problem? Thanks, Dean. PS. It's Ubuntu 12.04, Git, nginx, bind9, amazon aws, bitbucket...

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  • IE Sessions in Terminal Server

    - by Jacob
    Currently we are using WADE middleware for our order processing operation. We have about 40 operators that use 1 terminal server to open IE 8 to access the WADE middleware. To me, it's random, but every now and then someone will come to me and tell me that IE has a "Page cannot be displayed" or "HTTP Error 500" error. I did a bit of testing on my local machine and I never get this error while doing normal operations. Although, when I open one session with username "test" and then login to the wade admin console as admin, I run into problems. I do not run into problems until I logout of the wade admin. Once I logout of the Wade admin, my "test" session says "page cannot be displayed". This makes me think the IE user sessions on the terminal service are cross talking. Does anyone have any possible settings I can change in IE or do you think this is an issue with the middleware? The Terminal Server is Windows 2003, btw.

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  • What are the mandatory Linux kernel modules to run inside of ESXi

    - by Marcin
    I'm used to rolling my own kernels for servers, as it nicely minimizes the number of exploits (and the resulting patches) to take care of. In a traditional (bare metal) world, the whole process is about knowing what you have (hardware), and what you need (Ethernet, IPv4, iptables, etc.) In a virtualized environment, some things stay the same (still need Ethernet and IPv4), some things go away (power management), and then there are some new needs (vxnet3, or vmware-tools, even though that's compiled outside of the kernel). So my question mostly concerns itself with the last two categories: what can I remove completely, and what new stuff do I want? For example, what IO scheduler do I want, if all my disk operations are going through another filesystem/scheduler/cache to get to the virtual disk? Do I need hyper-threading enabled, or is the VM going to show them to me anyway as a CPU anyway? Do I need Large Receive Offload turned on, or is that something that the hypervisor's network drivers are going to do for me?

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  • After Upgrading Ubuntu to 9.10 my hard drive now has a warning.

    - by Sean
    it is a 500gb hard drive format as ext3 path /dev/sdc1 The disk utility does not even see this. This Warning is from gparted: e2label: No such device or address while trying to open /dev/sdc1 Couldn't find valid filesystem superblock. Couldn't find valid filesystem superblock. dump2fs 1.41.9 (22-Aug-2009) dumpe2fs: No such device or address while trying to open /dev/sdc1 Unable to read contents of this file system? Because of this some operations may be unavailable. END OF ERROR MESSAGE Did I lose something during the upgrade of the system? Was it the hard drive or the Ubuntu system that went bad?

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  • Problem with NHibernate

    - by Bernard Larouche
    I am trying to get a list of Products that share the Category. NHibernate returns no product which is wrong. Here is my Criteria API method : public IList<Product> GetProductForCategory(string name) { return _session.CreateCriteria(typeof(Product)) .CreateCriteria("Categories") .Add(Restrictions.Eq("Name", name)) .List<Product>(); } Here is my HQL method : public IList<Product> GetProductForCategory(string name) { return _session.CreateQuery("select from Product p, p.Categories.elements c where c.Name = :name").SetString("name",name).List<Product>(); } Both methods return no product when they should return 2 products. Here is the Mapping for the Product class : <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="CBL.CoderForTraders.DomainModel" namespace="CBL.CoderForTraders.DomainModel"> <class name="Product" table="Products" > <id name="_persistenceId" column="ProductId" type="Guid" access="field" unsaved-value="00000000-0000-0000-0000-000000000000"> <generator class="assigned" /> </id> <version name="_persistenceVersion" column="RowVersion" access="field" type="int" unsaved-value="0" /> <property name="Name" column="ProductName" type="String" not-null="true"/> <property name="Price" column="BasePrice" type="Decimal" not-null="true" /> <property name="IsTaxable" column="IsTaxable" type="Boolean" not-null="true" /> <property name="DefaultImage" column="DefaultImageFile" type="String"/> <bag name="Descriptors" table="ProductDescriptors"> <key column="ProductId" foreign-key="FK_Product_Descriptors"/> <one-to-many class="Descriptor"/> </bag> <bag name="Categories" table="Categories_Products" > <key column="ProductId" foreign-key="FK_Products_Categories"/> <many-to-many class="Category" column="CategoryId"></many-to-many> </bag> <bag name="Orders" generic="true" table="OrderProduct" > <key column="ProductId" foreign-key="FK_Products_Orders"/> <many-to-many column="OrderId" class="Order" /> </bag> </class> </hibernate-mapping> And finally the mapping for the Category class : <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="CBL.CoderForTraders.DomainModel" namespace="CBL.CoderForTraders.DomainModel" default-access="field.camelcase-underscore" default-lazy="true"> <class name="Category" table="Categories" > <id name="_persistenceId" column="CategoryId" type="Guid" access="field" unsaved-value="00000000-0000-0000-0000-000000000000"> <generator class="assigned" /> </id> <version name="_persistenceVersion" column="RowVersion" access="field" type="int" unsaved-value="0" /> <property name="Name" column="Name" type="String" not-null="true"/> <property name="IsDefault" column="IsDefault" type="Boolean" not-null="true" /> <property name="Description" column="Description" type="String" not-null="true" /> <many-to-one name="Parent" column="ParentID"></many-to-one> <bag name="SubCategories" inverse="true"> <key column="ParentID" foreign-key="FK_Category_ParentCategory" /> <one-to-many class="Category"/> </bag> <bag name="Products" table="Categories_Products"> <key column="CategoryId" foreign-key="FK_Categories_Products" /> <many-to-many column="ProductId" class="Product"></many-to-many> </bag> </class> </hibernate-mapping> Can you see what could be the problem ?

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  • Sharepoint 2007 Event ID 6482

    - by Dave M
    Our two server SharePoint 2007 SP2 farm has an issue. Event ID 6482 appears in the Application log of the Web front end many times a day. Often many time a minute. The full error is from Office SharePoint Server Event Type: Error Event Source: Office SharePoint Server Event Category: Office Server Shared Services Event ID: 6482 Date: 11/12/2009 Time: 3:05:22 PM User: N/A Computer: XXXXXX Description: Application Server Administration job failed for service instance Microsoft.Office.Server.Search.Administration.SearchServiceInstance (36a9b7ef-59aa-4f94-8887-8bf7b56f2f91). Reason: Error during encryption or decryption. System error code 0. Techinal Support Details: System.ArgumentException: Error during encryption or decryption. System error code 0. at Microsoft.Office.Server.Search.Administration.SearchServiceInstance.SynchronizeDefaultContentSource(IDictionary applications) at Microsoft.Office.Server.Search.Administration.SearchServiceInstance.Synchronize() at Microsoft.Office.Server.Administration.ApplicationServerJob.ProvisionLocalSharedServiceInstances(Boolean isAdministrationServiceJob) For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp. The SharePoint site appears to be functioning normally and Search returns expected results. Any suggestions would be appreciated

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  • Should I split my website into different servers

    - by Nyxynyx
    I have a website where a user uploads photos, the photos gets resized and thumbnailed, and stored on the server. At the same time, there are some INSERTS into a MySQL table regarding the photo uploaded (like description, user id etc). The site currently runs off a managed VPS, and I love the support it provides. However it is expensive to store the many small photos and the resizing and thumbnailing processes do cause spikes on the app performance. (Amazon S3 is pretty expensive, especially considering the costs for uploading many small files) Question: Will it be a good idea to move the image processing operations and image storage to another server which is an unmanaged dedicated server with a much lower cost/gb and keep the current VPS for its 24/7 support and hosting the webapp? Or should I move the entire site to the dedicated server? VPS Specs 16 cores 2.4GHz (E5620) 1GB memory 60GB Storage 3.5TB transfer $43/mth Managed (24/7) Dedicated Specs i3 2130 2 cores 3.4+ GHz 16 GB DDR3 2 x 1TB SATA2 storage 15 TB transfer $79/mth Unmanaged (Weekdays support) Software used Apache PHP MySQL Solr PostgreSQL ImageMagick

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  • ISCSI: Ethernet cable maximum length vs. SCSI command timeout

    - by Jeremy Hajek
    I have a question about a non-optimal setup and the practical implications of this. Ideally you would place the ESXi server right in the same room as the FreeNas white box end of question. My situation is this: I have a run of ~125ft of Cat 5e connecting a ESXi server to a FreeNas whitebox in the server room. I know the distance of the ethernet cable is within the maximum distance for ethernet traffic but I have two questions... Can Cat 5e support gigbit speeds at that distance if the switch on the back end is a linksys SRW-2048? Should I be concerned about the distance causing data read and write timeouts in the SCSI portion--(disk operations of the ESXi)?

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  • NullPointerException using EndlessAdapter with SimpleAdapter

    - by android_dev
    Hello, I am using EndlessAdapter from commonsguy with a SimpleAdapter. I can load data when I make a scroll down without problems, but I have a NullPointerException when I make a scroll up. The problem is in the method @Override public View getView(int position, View convertView,ViewGroup parent) { return wrapped.getView(position, convertView, parent); } from the class AdapterWrapper. The call to wrapped.getView(position, convertView,parent) raises the exception and I don´t know why. This is my implementation of EndlessAdapter: //Inner class in SearchTextActivity class DemoAdapter extends EndlessAdapter { private RotateAnimation rotate = null; DemoAdapter(ArrayList<HashMap<String, String>> result) { super(new SimpleAdapter(SearchTracksActivity.this, result, R.layout.textlist_item, PROJECTION_COLUMNS, VIEW_MAPPINGS)); rotate = new RotateAnimation( 0f, 360f, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f); rotate.setDuration(600); rotate.setRepeatMode(Animation.RESTART); rotate.setRepeatCount(Animation.INFINITE); } @Override protected View getPendingView(ViewGroup parent) { View row=getLayoutInflater().inflate(R.layout.textlist_item, null); View child=row.findViewById(R.id.title); child.setVisibility(View.GONE); child=row.findViewById(R.id.username); child.setVisibility(View.GONE); child=row.findViewById(R.id.throbber); child.setVisibility(View.VISIBLE); child.startAnimation(rotate); return row; } @Override @SuppressWarnings("unchecked") protected void rebindPendingView(int position, View row) { HashMap<String, String> res = (HashMap<String, String>)getWrappedAdapter().getItem(position); View child=row.findViewById(R.id.title); ((TextView)child).setText(res.get("title")); child.setVisibility(View.VISIBLE); child=row.findViewById(R.id.username); ((TextView)child).setText(res.get("username")); child.setVisibility(View.VISIBLE); ImageView throbber=(ImageView)row.findViewById(R.id.throbber); throbber.setVisibility(View.GONE); throbber.clearAnimation(); } boolean mFinal = true; @Override protected boolean cacheInBackground() { EditText searchText = (EditText)findViewById(R.id.searchText); String textToSearch = searchText.getText().toString(); Util.getSc().searchText(textToSearch , offset, limit, new ResultListener<ArrayList<Text>>() { @Override public void onError(Exception e) { e.toString(); mFinal = false; } @Override public void onSuccess(ArrayList<Text> result) { if(result.size() == 0){ mFinal = false; }else{ texts.addAll(result); offset++; } } }); return mFinal; } @Override protected void appendCachedData() { for(Text text : texts){ result.add(text.getMapValues()); } texts.clear(); } } And I use it this way: public class SearchTextActivity extends AbstractListActivity { private static final String[] PROJECTION_COLUMNS = new String[] { TextStore.Text.TITLE, TextStore.Text.USER_NAME}; private static final int[] VIEW_MAPPINGS = new int[] { R.id.Text_title, R.id.Text_username}; ArrayList<HashMap<String, String>> result; static ArrayList<Text> texts; static int offset = 0; static int limit = 1; @Override void onAbstractCreate(Bundle savedInstance) { setContentView(R.layout.search_tracks); setupViews(); } private void setupViews() { ImageButton searchButton = (ImageButton)findViewById(R.id.searchButton); updateView(); } SimpleAdapter adapter; void updateView(){ if(result == null) { result = new ArrayList<HashMap<String, String>>(); } if(tracks == null) { texts = new ArrayList<Text>(); } } public void sendQuery(View v){ offset = 0; texts.clear(); result.clear(); setListAdapter(new DemoAdapter(result)); } } Does anybody knows what could be the problem? Thank you in advance

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  • Recommended integration mechanism for bi-directional, authenticated, encrypted connection in C clien

    - by rcampbell
    Let me first give an example. Imagine you have a single server running a JVM application. This server keeps a collection of N equations, once for each client: Client #1: 2x Client #2: 1 + y Client #3: z/4 This server includes an HTTP interface so that random visitors can type https://www.acme.com/client/3 int their browsers and see the latest evaluated result of z/4. The tricky part is that either the client or the server may change the variable value at any time, informing the other party immediately. More specifically, Client #3 - a C app - can initially tell the server that z = 20. An hour later that same client informs the server that z = 23. Likewise the server can later inform the client that z = 28. As caf pointed out in the comments, there can be a race condition when values are changed by the client and server simultaneously. The solution would be for both client and server to send the operation performed in their message, which would need to be executed by the other party. To keep things simple, let's limit the operations to (commutative) addition, allowing us to disregard message ordering. For example, the client seeds the server with z = 20: server:z=20, client:z=20 server sends {+3} message (so z=23 locally) & client sends {-2} message (so z=18 locally) at the exact same time server receives {-2} message at some point, adds to his local copy so z=21 client receives {+3} message at some point, adds to his local copy so z=21 As long as all messages are eventually evaluated by both parties, the correct answer will eventually be given to the users of the client and server since we limited ourselves to commutative operations (addition of 3 and -2). This does mean that both client and server can be returning incorrect answers in the time it takes for messages to be exchanged and processed. While undesirable, I believe this is unavoidable. Some possible implementations of this idea include: Open an encrypted, always on TCP socket connection for communication Pros: no additional infrastructure needed, client and server know immediately if there is a problem (disconnect) with the other party, fairly straightforward (except the the encryption), native support from both JVM and C platforms Cons: pretty low-level so you end up writing a lot yourself (protocol, delivery verification, retry-on-failure logic), probably have a lot of firewall headaches during client app installation Asynchronous messaging (ex: ActiveMQ) Pros: transactional, both C & Java integration, free up the client and server apps from needing retry logic or delivery verification, pretty straightforward encryption, easy extensibility via message filters/routers/etc Cons: need additional infrastructure (message server) which must never fail, Database or file system as asynchronous integration point Same pros/cons as above but messier RESTful Web Service Pros: simple, possible reuse of the server's existing REST API, SSL figures out the encryption problem for you (maybe use RSA key a la GitHub for authentication?) Cons: Client now needs to run a C HTTP REST server w/SSL, client and server need retry logic. Axis2 has both a Java and C version, but you may be limited to SOAP. What other techniques should I be evaluating? What real world experiences have you had with these mechanisms? Which do you recommend for this problem and why?

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  • Do you have suggestions for these assembly mnemonics?

    - by Noctis Skytower
    Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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  • How do I log file system read/writes by filename in Linux?

    - by Casey
    I'm looking for a simple method that will log file system operations. It should display the name of the file being accessed or modified. I'm familiar with powertop, and it appears this works to an extent, in so much that it show the user files that were written to. Is there any other utilities that support this feature. Some of my findings: powertop: best for write access logging, but more focused on CPU activity iotop: shows real time disk access by process, but not file name lsof: shows the open files per process, but not real time file access iostat: shows the real time I/O performance of disk/arrays but does not indicate file or process

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  • Large file copy from NFS to local disk performance drop

    - by Bernhard
    I'm trying to copy a 200GB file from an NFS mount to a local disk. The local disk is an XFS filesystem on a LVM on top of a RAID 5 system (hardware RAID controler). I'm using rsync to monitor the transfer speed. At the beginning the IO speed is about 200MB/s, stable for the first 18GB. But then the performance drops by a factor of 10-20 and never recovers to the initial rate. Sometimes it reaches about 50-100MB/s but just for a few seconds and then the process seems to hang for a bit. At the same time all file-stat operations on the target filesystem are blocking for a long time (minutes). Also interrupting the copy process blocks for several minutes, a sub-sequent delete of the partly copied file takes also several minutes. Any ideas what could be causing this?

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  • Apple file sharing: bind to a specific interface

    - by Cesar
    My customer have an office small office with just a wifi router. He use this router for internet connectivity and file transfer operations between the desktops. Recently the file transfer activity between desktop (all osx based) is increased a lot so he bought a switch (no connected to the router, too far away) for transfer the file over the cable instead over the wifi. Problem: How to bind the file sharing service just to the Ethernet interface and exclude the wifi interface ? (actually the service binds to the wifi automatically and there are no options about the interface binding)

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  • How do I log which process is deleting a file on Windows XP?

    - by Jordan Milne
    I'm having an issue with a file getting deleted seemingly randomly throughout the day. The vendor of the software whose file is getting deleete says that another piece of software installed on the computer is deleting it, while the other software's vendor says the opposite. I've tried using Process Monitor so I can pinpoint exactly what's deleting it, but even when filtered specifically to that file, createfile operations are being triggered a few times a second, and I can't seem to filter it to deletions specifically. Is there a tool or script I can use to specifically monitor deletion attempts on a single file?

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  • Windows 7 just restarts, no BSOD, shows "Event ID 14 volsnap"

    - by Mdc007
    My Windows 7 just restarts without giving me a BSOD. When it reboots, it will hang sometimes and you have to let it rest. Sometimes it will print a message saying that Hal.dll is missing or corrupt. When it does restart I can't run a backup or a clone drive – it comes up with constant errors. I tried to run chkdsk – it says everything's clean. What is really puzzling is SyncToy on a different drive hangs half way through and won't run either. Machine: OCZ SSD Agility 2 for C drive SATA HDD for programs, documents on D drive MSI AMD 880 chipset Event viewer says something about critical power failure I/O operations and "Event ID 14 volsnap" – but that is just telling me the computer powered off which I already know.

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  • Beginner question: ArrayList can't seem to get it right! Pls help

    - by elementz
    I have been staring at this code all day now, but just can't get it right. ATM I am just pushing codeblocks around without being able to concentrate anymore, with the due time being within almost an hour... So you guys are my last resort here. I am supposed to create a few random balls on a canvas, those balls being stored within an ArrayList (I hope an ArrayList is suitable here: the alternative options to choose from were HashSet and HashMap). Now, whatever I do, I get the differently colored balls at the top of my canvas, but they just get stuck there and refuse to move at all. Apart from that I now get a ConcurrentModificationException, when running the code: java.util.ConcurrentModificationException at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372) at java.util.AbstractList$Itr.next(AbstractList.java:343) at BallDemo.bounce(BallDemo.java:109) Reading up on that exception, I found out that one can make sure ArrayList is accessed in a threadsafe manner by somehow synchronizing access. But since I have remember fellow students doing without synchronizing, my guess is, that it would actually be the wrong path to go. Maybe you guys could help me get this to work, I at least need those stupid balls to move ;-) /** * Simulate random bouncing balls */ public void bounce(int count) { int ground = 400; // position of the ground line System.out.println(count); myCanvas.setVisible(true); // draw the ground myCanvas.drawLine(50, ground, 550, ground); // Create an ArrayList of type BouncingBalls ArrayList<BouncingBall>balls = new ArrayList<BouncingBall>(); for (int i = 0; i < count; i++){ Random numGen = new Random(); // Creating a random color. Color col = new Color(numGen.nextInt(256), numGen.nextInt(256), numGen.nextInt(256)); // creating a random x-coordinate for the balls int ballXpos = numGen.nextInt(550); BouncingBall bBall = new BouncingBall(ballXpos, 80, 20, col, ground, myCanvas); // adding balls to the ArrayList balls.add(bBall); bBall.draw(); boolean finished = false; } for (BouncingBall bBall : balls){ bBall.move(); } } This would be the original unmodified method we got from our teacher, which only creates two balls: /** * Simulate two bouncing balls */ public void bounce() { int ground = 400; // position of the ground line myCanvas.setVisible(true); myCanvas.drawLine(50, ground, 550, ground); // draw the ground // crate and show the balls BouncingBall ball = new BouncingBall(50, 50, 16, Color.blue, ground, myCanvas); ball.draw(); BouncingBall ball2 = new BouncingBall(70, 80, 20, Color.red, ground, myCanvas); ball2.draw(); // make them bounce boolean finished = false; while(!finished) { myCanvas.wait(50); // small delay ball.move(); ball2.move(); // stop once ball has travelled a certain distance on x axis if(ball.getXPosition() >= 550 && ball2.getXPosition() >= 550) { finished = true; } } ball.erase(); ball2.erase(); } }

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  • Looking at desktop virtualization, but some users need 3D support. Is HP Remote Graphics a viable solution?

    - by Ryan Thompson
    My company is looking at desktop virtualization, and are planning to move all of the desktop compute resources into the server room or data center, and provide users with thin clients for access. In most cases, a simple VNC or Remote Desktop solution is adequate, but some users are running visualizations that require 3D capability--something that VNC and Remote Desktop cannot support. Rather than making an exception and providing desktop machines for these users, complicating out rollout and future operations, we are considering adding servers with GPUs, and using HP's Remote Graphics to provide access from the thin client. The demo version appears to work acceptably, but there is a bit of a learning curve, it's not clear how well it would work for multiple simultaneous sessions, and it's not clear if it would be a good solution to apply to non-3D sessions. If possible, as with the hardware, we want to deploy a single software solution instead of a mishmash. If anyone has had experience managing a large installation of HP Remote Graphics, I would appreciate any feedback you can provide.

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  • Speed up file access on home network

    - by kurasa
    I have 2 PCs (Windows 7 Ultimate) and a Mac running Windows 7 using vmware fusion on my home network tied together using WRN1000 NETGEAR Router On one of the PC's I have a set of file (MYOB .myo). These use a data source to access the data in the files. Operations (reading,writing) to the .myo on the PC which hosts the files is fine but the other 2 it is painfully slow/unreliable and I am wondering what I can do to speed this up. Some ideas I have are 1. Turn off the Windows firewall on all the windows installations on the home network 2. Buy another router. Specifically a router which I can connect a USB flash drive on the back where I can put the .myo files and all the PC can access the files from the USB flash drive on the router (does this speed things up?) Any advice greatly appreciated on how I can speed up this access to data

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