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• Recommendation for a simple no-frills Windows PDF printer driver?

  - by Scott Bussinger

  I'm looking for an extremely simple Windows PDF printer driver that I can recommend to clients. Ideally it would have these characteristics: When you print something, it should just create it as a temporary file and then display it in their default PDF viewer with no prompting. If they want to save it, they can save it manually from inside the viewer. This workflow should be with no special post-install configuration. Installation should be very simple. A double click the installation program and click "Finish" sort of thing. No complicated multi-step installation, no asking questions your grandmother wouldn't know the answer to (preferably no questions at all), no extra crap being installed. An option for a completely silent installation would be nice, but not necessary. Ideally it would be free to simplify their installing on a small network, but low cost is an option. I've tried a quite a few but none really fit the bill. Some can achieve the first goal but only after careful configuration, some try to install extra toolbars, some have other installation complexities that would make it hard for extremely novice users to succeed. Any suggestions? Thanks!

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• What is the max connections via remote desktop for a small server?

  - by Jay Wen

  I have a small server running MS Server 2012. The CPU is a Xeon E3-1230 V2 @ 3.30GHz, 4 Cores, 8 Logical Processors, 8 GB RAM. Main HD is a Samsung 840, and the big storage is a 4 disk WD Black Raid 10 Array in a Synology NAS enclusure. My question is: given this hardware, approximately how many users can the system support via "Remote Desktop Connection"? Assume there are no licensing limits. These are not admin users. I know there is a two admin limit. This boils down to: What resources does one remote connection require? RAM? % of the CPU? Networking bandwidth? I guess the base case would be for a conection where the user is inactive or simply browsing cnn. Once you know this, you know how many you could fit on the machine before something is maxed-out. In reality, users would be mostly on Excel (multi-MB spreadsheets). I know the approx. resources currently required by each copy of Excel.

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• Separate Certificate by Subdomain (With multiple IPs)

  - by Brian

  Note: Yes, I realize this problem is easier to solve by just using 1 multi-domain or wildcard certificate. I wish to have an ASP.NET site running on IIS with 2 SSL domains sharing 1 web application but using separate certificates. Assuming I have 2 certificates, this can be solved on IIS7 as follows: Web Application1: Binding 1: http, 80, IP Address *, Host Name * Binding 2: https, 443, IPADDRESS1, using CERTDOMAIN1 (DOMAIN1 resolves to IPADDRESS1) Binding 3: https, 443, IPADDRESS2, using CERTDOMAIN2 (DOMAIN2 resolves to IPADDRESS2) That is to say, 2 certificates and 2 ip addresses, but both mapped to the same web application. In IIS6, the closest I have been able to come to this configuration is: Web Application1: Binding 1: http, 80, IPADDRESS1 Binding 2: https, 443, IPADDRESS1, using CERTDOMAIN1 (DOMAIN1 resolves to IPADDRESS1) Web Application2: Binding 1: http, 80, IPADDRESS2 Binding 2: https, 443, IPADDRESS2, using CERTDOMAIN2 (DOMAIN2 resolves to IPADDRESS2) That is to say, 2 certificates and 2 IP addresses, 2 web applications, both mapped to the same file location. The IIS6 solution is not optimal. Even if sharing an application pool, there are still costs associated with running the same site as two applications. Is upgrading from IIS6 to IIS7 a legitimate way to resolve this problem? Is there an IIS6 way to map 2 IP addresses within the same web application to different certificates?

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• rsync per-site configuration file?

  - by Scott

  I know how to configure a per-site entry for ssh, but is there any kind of a client configuration for rsync that allows per-site configuration options and aliases or similar shortcuts like the .ssh/config? I'm curious because I have a minimal ssh server installed on my android phone and I also have a minimal rsync tool on it as well. I'm getting tired of having to root login onto the phone and sym-link both tools to standard places the android OS looks for executables as the ssh server is bare bones and has a typical *bear multi-link binary for the basic unix commands (that does not include rsync) I end up having to include --rsync-path=/path/to/rsync/android/files/rsync every time I want to do any rsyncing of the files on my phone, but this path is always the same. I've gotten around it in the meantime with a glob approach in a shell script wrapper, but this sometimes limits the customization I can do with the rsync call. I'm just wondering if there is anything similar to the .ssh/config file where I can create an alias for my phone (e.g. 'android') where specifying rsync android:/mnt/sdcard will automatically assume --rsync-path=/blah/blah/blah --no-g --no-p --no-t etc. Tre`

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• How to resume XMPP groupchat window in Irssi (using bitlbee)?

  - by mcnesium

  I use Bitlbee to chat in XMPP-networks within my IRC-client Irssi. This works great so far, and recently I started using XMPP Multi User Chats as an alternative to IRC-channels. I set up a channel using chat add <account> <[email protected]> in the &bitlbee control window, set chan <room> set autojoin true and entered /join #room in the &bitlbee window to join that groupchat. It then appears as a unique Irssi window in the status bar. This seems to work ok too, but with one exception: Since I idle in the channels 24/7 my irssi has to cope with the every-night-24h-DSL-disconnection by the ISP. After it automatically reconnects, it does kind of rejoin that XMPP-groupchat, but the traffic of the groupchat does not go back to the unique irssi window, but keeps flooding &bitlbee with messages from root telling me about a Groupchat Message from unknown JID <jid>: <message> - which is the traffic of the groupchat. The unique groupchat window is gone after the reconnect, and I will again have to go /join #room in &bitlbee to get it back. Even worse, the window number is unused before I rejoin the groupchat, and if I get a query from any network, the window nests in that unused window spot, so I will first have to remove that query from the spot, and then move the rejoined groupchat to that window number. I want my groupchat window to resume after the reconnect just like every other IRC channel too. How can I get this done? Any ideas?

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• What is the risk of introducing non standard image machines to a corporate environment

  - by Troy Hunt

  I’m after some feedback from those in the managed desktop or network security space on the risks of introducing machines that are not built on a standard desktop image into a large corporate environment. This particular context relates to the standard corporate image (32 bit Win XP) in a large multi-national not being suitable for a particular segment of users. In short, I’m looking at what hurdles we might come across by proposing the introduction of machines which are built and maintained by a handful of software developers and not based on the corporate desktop image (proposing 64 bit Win 7). I suspect the barriers are primarily around virus definition updates, the rollout of service packs and patches and the compatibility of existing applications with the newer OS. In terms of viruses and software updates, if machines were using common virus protection software with automated updates and using Windows Update for service packs and patches, is there still a viable risk to the corporate environment? For that matter, are large corporate environments normally vulnerable to the introduction of a machine not based on a standard image? I’m trying to get my head around how real the risk of infection and other adverse events are from machines being plugged into the network. There are multiple scenarios outside of just the example above where this might happen (i.e. a vendor plugging in a machine for internet access during a presentation). Would a large corporate network normally be sufficiently hardened against such innocuous activity? I appreciate the theory as to why policies such as standard desktop images exist, I’m just interested in the actual, practical risk and how much a network should be protected by means other than what is managed on individual PCs.

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• What is the typical maximum number of database connections for Oracle running on Windows server ?

  - by Sake

  We are maintaining a database server that serve a large number of clients. Each client typically running serveral client-applications. The total number of connections to the database server (Oracle 9i) is reaching 800 connections on peak load. The windows 2003 server is starting to run out of memory. We are now planning to move to 64bit Windows in order to gain higher memory capability. As a developer I suggest moving to multi-tier architecture with conneciton pooling, which I believe is a natural solution to this problem. However, in order to support my idea, I want the information on: what exactly is the typical number of connections allowed for Oracle database ? What is the problem when the number connections is too high ? Too much memory comsumption ? or too many sockets opened ? or too many context switching between threads ? To be a little bit specific, how could Oracle Forms application scale to thousand of users without facing this problem ? Shall Oracle RAC applied to this case ? I'm sure the answer to this question should depend on quite a number of factors, like the exact spec of the hardware being used. I'm expecting a rough estimation or some experience from the real world.

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• Vim: auto-comment in new line

  - by padde

  Vim automatically inserts a comment when I start a new line from a commented out line, because I have set formatoptions=tcroql. For example (cursor is *): // this is a comment* and after hitting <Enter> (insert mode) or o (normal mode) i am left with: // this is a comment // * This feature is very handy when writing long multi-line comments, but often I just want a single line comment. Now if I want to end the comment series I have several options: hit <Esc>S hit <BS> three times Both of these afford three keystrokes, taken together with the <Enter> this means four keystrokes for a new line, which I think is too much. Ideally, I would like to just hit <Enter> a second time to be left with: // this is a comment * It is important that the solution will also work with different indentation levels, i.e. int main(void) { // this is a comment* } hit <Enter> int main(void) { // this is a comment // * } hit <Enter> int main(void) { // this is a comment * } I think I have seen this feature in some text editor a few years ago but I do not recall which one it was. Is anyone aware of a solution that will do this for me in Vim? Pointers in the right direction on how to roll my own solution are also very welcome.

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• Does Mac OS X throttle the RATE of socket creation?

  - by pbhogan

  This may seem programming related, but this is an OS question. I'm writing a small high performance daemon that takes thousands of connections per second. It's working fine on Linux (specifically Ubuntu 9.10 on EC2). On Mac OS X if I throw a few thousand connections at it (roughly about 16350) in a benchmark that simply opens a connection, does it's thing and closes the connection, then the benchmark program hangs for several seconds waiting for a socket to become available before continuing (or timing out in the process). I used both Apache Bench as well as Siege (to make sure it wasn't the benchmark application). So why/how is Mac OS X limiting the RATE at which sockets can be used, and can I stop it from doing this? Or is there something else going on? I know there is a file descriptor limit, but I'm not hitting that. There is no error on accepting a socket, it's simply hangs for a while after the first (roughly) 16000, waiting -- I assume -- for the OS to release a socket. This shouldn't happen since all prior the sockets are closed at that point. They're supposed to come available at the rate they're closed, and do on Ubuntu, but there seems to be some kind of multi (5-10?) second delay on Mac OS X. I tried tweaking with ulimit every-which-way. Nada.

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• Does Mac OS X throttle the RATE of socket creation?

  - by pbhogan

  This may seem programming related, but this is an OS question. I'm writing a small high performance daemon that takes thousands of connections per second. It's working fine on Linux (specifically Ubuntu 9.10 on EC2). On Mac OS X if I throw a few thousand connections at it (roughly about 16350) in a benchmark that simply opens a connection, does it's thing and closes the connection, then the benchmark program hangs for several seconds waiting for a socket to become available before continuing (or timing out in the process). I used both Apache Bench as well as Siege (to make sure it wasn't the benchmark application). So why/how is Mac OS X limiting the RATE at which sockets can be used, and can I stop it from doing this? Or is there something else going on? I know there is a file descriptor limit, but I'm not hitting that. There is no error on accepting a socket, it's simply hangs for a while after the first (roughly) 16000, waiting -- I assume -- for the OS to release a socket. This shouldn't happen since all prior the sockets are closed at that point. They're supposed to come available at the rate they're closed, and do on Ubuntu, but there seems to be some kind of multi (5-10?) second delay on Mac OS X. I tried tweaking with ulimit every-which-way. Nada.

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• VMware ESX Linux Guest Customization

  - by andyh_ky

  Hello, I am interested in deploying several RHEL 4 Update 8 virtual machines for creation of a test environment. Here are the steps I am taking: In off hours, P2V/V2V the production machines and convert them to templates Deploy the virtual machines with a customization specification that changes hostname, IP address I am interested in how these processes are done and if there are any options for further customization. Are the machines brought on the network when they are powered on, before they are reconfigured? Is there a potential IP address conflict? Is there an option to run additional scripts which reside on the guest as a part of the reconfiguration? For example, restoring an Oracle Database. This is an option with Windows guests and sysprep, but I have been unable to locate anything showing a RHEL equivalent. I am dealing with a multi tier application. The main issue I am attempting to mitigate is that the application servers reference database servers by hostname and in tnsnames files. I am interested in scripting the reconfiguration of the application in the deployment so that the app/db servers are pointing to the test environment. I am OK with placing the 'cleanup' script on the source and executing it after the machine has been brought up. I am interested in the automation of the script's execution post clone/boot, as well as if there could be an IP address conflict. (cross posted to VMTN's ESX 4 community)

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• How to decouple development server from Internet?

  - by intoxicated.roamer

  I am working in a small set-up where there are 4 developers (might grow to 6 or 8 in cuople of years). I want to set-up an environment in which developers get an internet access but can not share any data from the company on internet. I have thought of the following plan: Set-up a centralized git server (Debian). The server will have an internet access. A developer will only have git account on that server, and won't have any other account on it. Do not give internet access to developer's individual machine (Windows XP/Windows 7). Run a virtual machine (any multi-user OS) on the centralized server (the same one on which git is hosted). Developer will have an account on this virtual machine. He/she can access internet via this virtual machine. Any data-movement between this virtual machine and underlying server, as well as any of the developer's machine, is prohibited. All developers require USB port on their local machine, so that they can burn their code into a microcontroller. This port will be made available only to associated software that dumps the code in a microcontroller (MPLAB in current case). All other softwares will be prohibited from accessing the port. As more developers get added, providing internet support for them will become difficult with this plan as it will slow down the virtual machine running on the server. Can anyone suggest an alternative ? Are there any obvious flaws in the above plan ? Some key details of the server are as below: 1) OS:Debian 2) RAM: 8GB 3) CPU: Intel Xeon E3-1220v2 4C/4T

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• [openVPN] server & client on same machine . And multiple VPN servers

  - by HiWorld

  Hello everyone, im stucked configuring openvpn to build a multi vpn connection. like this: CLIENT - VPN1 - VPN2 - INTERNET Well, i already have and know how to done a normal sigle vpn but want to use a chain of vpns, so i explain what i have done and how i did it. ON VPN1. i have 1 openvpn instance running as server( where client connect to) and another as client connecting to VPN2 running as server. { Here comes the problem } when i connect VPN1 as client of VPN2 i cant connect to VPN1 from CLIENT, my question is HOW TO procced with this... Also have another third instance working as server to use VPN1 without chains. ON VPN2. 1 openvpn instance as server where VPN1 will connect and then forward to the NET. Im using TUN interface on configs. And iptables are on this way: VPN1 - openvpn ip server1 : 192.168.6.0 / ip as client of VPN2: 192.168.5.70 iptables -t nat -A POSTROUTING -s 192.168.6.0 -j SNAT --to-source 192.168.5.70 VPN2 - openvpn ip server2 : 192.168.5.0 iptables -t nat -A POSTROUTING -s 192.168.5.0/24 -j SNAT --to-source EXTERNAL_IP_TO_INTERNET Hope someone help me with this. thanks in advance

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• Methods and practices for managing a network that has no internet connection

  - by FaultyJuggler

  Originally asked in Super User but realized this belongs here. Long story short, I am setting up a network with 32 servers of varying specs that will be used for testing and development. We will be using RedHat Linux, we also do not have a router as of yet and were looking into making one of the servers act as our router/DHCP etc. The small cluster will be on an isolated network with no internet. I can use external harddrives and discs to transfer anything from external sources into machines on the network, so this isn't a locked down secure network, it just won't have a direct connection to the outside world. I've worked on such setups before, but always long after they were setup. So I'm reaching out to see what everyone knows as far as how groups have handled initial setup and maintenance of such a situation. What is the best way to get them all configured and up to date? What are the best ways to automate updates, network wide installs, etc. With the only given that I have large multi-terabyte external hard drives that would be used to drop whatever files are needed onto a central server, how do i then distribute those files and install their contents? I've done perl scripting, some teammates have played with puppet, so we aren't completely in the dark, I just wanted to avoid reinventing the wheel since this is a common challenge.

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• Integrating external computer into a domain - some recommendations please

  - by TomTom

  Given: * A multi loation company. Every office has local routers that connect to a central VPN capable rouer in a data center. All fine so far. We now need to move a computer off site into a hosting center across the globe, to get it closer to some supplier computers we work for. it will run limited logic but latency is important, and our latency so far is too large. This computer will be in a data center and does no require incoming connections except for adminsitrative purposes, although it needs outgoing connetions. I have no real chance to put one of my VPN routers there, sadly - otherwise I would have no problem. Usage of RRAs is not recommended (we had various probblems there over time). I could deal with it. The computer MUSt integrate into the corporate structure via VPN and join the domain and be fully "tracked" (controlled for performance). What is the best suggestion? So far it looks like my best bets woudl be to log in via RRAS and deal with whatever issues arise there plus uise the local firewall the limit incoming connections to this computer to what is needed (which runs down to an emergency RDP connection allowance). Anyone a better idea?

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• What is the potential for a FUSE mount to destabilize a Linux server?

  - by 200_success

  I'm a sysadmin for a multi-user server, where students in our department have shell accounts. One of our users has requested that we install sshfs on it. I'm debating whether it would be wise to install sshfs as suggested. My main concern is whether a FUSE mount could make our server less reliable. In my experience, bad things can happen to servers when an NFS server suddenly becomes unavailable — the load average shoots up, and you might not be able to unmount it cleanly, to the point where a hard reboot might be necessary. If a FUSE-mounted server suddenly disappears, how hard might it be to clean up the mess? Are there any other likely catastrophes or gotchas I should consider? At least with NFS, only root can mount, and we can choose to mount NFS servers that we consider to be reasonably reliable. Let's assume that our users have no hostile intentions, but might do stupid things accidentally. Also, I'm not really worried about the contents of the filesystems they might mount, since our users already have shell access and can copy anything they want to their home directory.

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• Visual Studio build fails: unable to copy exe-file from obj\debug to bin\debug

  - by Nailuj

  This is a question asked before, both here on Stack Overflow and other places, but none of the suggestions I've found this far has helped me, so I just have to try asking a new question. Scenario: I have a simple Windows Forms application (C#, .NET 4.0, Visual Studio 2010). It has a couple of base forms that most other forms inherit from, it uses Entity Framework (and POCO classes) for database access. Nothing fancy, no multi-threading or anything. Problem: All was fine for a while. Then, all out of the blue, Visual Studio failed to build when I was about to launch the application. I got the warning "Unable to delete file '...bin\Debug\[ProjectName].exe'. Access to the path '...bin\Debug\[ProjectName].exe' is denied." and the error "Unable to copy file 'obj\x86\Debug\[ProjectName].exe' to 'bin\Debug\[ProjectName].exe'. The process cannot access the file 'bin\Debug\[ProjectName].exe' because it is being used by another process." (I get both the warning and the error when running Rebuild, but only the error when running Build - don't think that is relevant?) I understand perfectly fine what the warning and error message says: Visual Studio is obviously trying to overwrite the exe-file while it the same time has a lock on it for some reason. However, this doesn't help me find a solution to the problem... The only thing I've found working is to shut down Visual Studio and start it again. Building and launching then works, untill I make a change in some of the forms, then I have the same problem again and have to restart... Quite frustrating! As I mentioned above, this seems to be a known problem, so there are lots of suggested solutions. I'll just list what I've already tried here, so people know what to skip: Creating a new clean solution and just copy the files from the old solution. Adding the following to the following to the project's pre-build event: if exist "$(TargetPath).locked" del "$(TargetPath).locked"   if not exist "$(TargetPath).locked" if exist "$(TargetPath)" move "$(TargetPath)" "$(TargetPath).locked" Adding the following to the project properties (.csproj file): <GenerateResourceNeverLockTypeAssembliestrue</GenerateResourceNeverLockTypeAssemblies However, none of them worked for me, so you can probably see why I'm starting to get a bit frustrated. I don't know where else to look, so I hope somebody has something to give me! Is this a bug in VS, and if so is there a patch? Or has I done something wrong, do I have a circular reference or similar, and if so how could I find out? Any suggestions are highly appreciated :)

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• How can I make a WPF TreeView data binding lazy and asynchronous?

  - by pauldoo

  I am learning how to use data binding in WPF for a TreeView. I am procedurally creating the Binding object, setting Source, Path, and Converter properties to point to my own classes. I can even go as far as setting IsAsync and I can see the GUI update asynchronously when I explore the tree. So far so good! My problem is that WPF eagerly evaluates parts of the tree prior to them being expanded in the GUI. If left long enough this would result in the entire tree being evaluated (well actually in this example my tree is infinite, but you get the idea). I would like the tree only be evaluated on demand as the user expands the nodes. Is this possible using the existing asynchronous data binding stuff in the WPF? As an aside I have not figured out how ObjectDataProvider relates to this task. My XAML code contains only a single TreeView object, and my C# code is: public partial class Window1 : Window { public Window1() { InitializeComponent(); treeView.Items.Add( CreateItem(2) ); } static TreeViewItem CreateItem(int number) { TreeViewItem item = new TreeViewItem(); item.Header = number; Binding b = new Binding(); b.Converter = new MyConverter(); b.Source = new MyDataProvider(number); b.Path = new PropertyPath("Value"); b.IsAsync = true; item.SetBinding(TreeView.ItemsSourceProperty, b); return item; } class MyDataProvider { readonly int m_value; public MyDataProvider(int value) { m_value = value; } public int[] Value { get { // Sleep to mimick a costly operation that should not hang the UI System.Threading.Thread.Sleep(2000); System.Diagnostics.Debug.Write(string.Format("Evaluated for {0}\n", m_value)); return new int[] { m_value * 2, m_value + 1, }; } } } class MyConverter : IValueConverter { public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { // Convert the double to an int. int[] values = (int[])value; IList<TreeViewItem> result = new List<TreeViewItem>(); foreach (int i in values) { result.Add(CreateItem(i)); } return result; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { throw new InvalidOperationException("Not implemented."); } } } Note: I have previously managed to do lazy evaluation of the tree nodes by adding WPF event handlers and directly adding items when the event handlers are triggered. I'm trying to move away from that and use data binding instead (which I understand is more in spirit with "the WPF way").

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• List of freely available programming books

  - by Karan Bhangui

  I'm trying to amass a list of programming books with opensource licenses, like Creative Commons, GPL, etc. The books can be about a particular programming language or about computers in general. Hoping you guys could help: Languages BASH Advanced Bash-Scripting Guide (An in-depth exploration of the art of shell scripting) C The C book C++ Thinking in C++ C++ Annotations How to Think Like a Computer Scientist C# .NET Book Zero: What the C or C++ Programmer Needs to Know About C# and the .NET Framework Illustrated C# 2008 (Dead Link) Data Structures and Algorithms with Object-Oriented Design Patterns in C# Threading in C# Common Lisp Practical Common Lisp On Lisp Java Thinking in Java How to Think Like a Computer Scientist Java Thin-Client Programming JavaScript Eloquent JavaScript Haskell Real world Haskell Learn You a Haskell for Great Good! Objective-C The Objective-C Programming Language Perl Extreme Perl (license not specified - home page is saying "freely available") The Mason Book (Open Publication License) Practical mod_perl (CreativeCommons Attribution Share-Alike License) Higher-Order Perl Learning Perl the Hard Way PHP Practical PHP Programming Zend Framework: Survive the Deep End PowerShell Mastering PowerShell Prolog Building Expert Systems in Prolog Adventure in Prolog Prolog Programming A First Course Logic, Programming and Prolog (2ed) Introduction to Prolog for Mathematicians Learn Prolog Now! Natural Language Processing Techniques in Prolog Python Dive Into Python Dive Into Python 3 How to Think Like a Computer Scientist A Byte of Python Python for Fun Invent Your Own Computer Games With Python Ruby Why's (Poignant) Guide to Ruby Programming Ruby - The Pragmatic Programmer's Guide Mr. Neighborly's Humble Little Ruby Book SQL Practical PostgreSQL x86 assembly Paul Carter's tutorial Lua Programming In Lua (for v5 but still largely relevant) Algorithms and Data Structures Algorithms Data Structures and Algorithms with Object-Oriented Design Patterns in Java Planning Algorithms Frameworks/Projects The Django Book The Pylons Book Introduction to Design Patterns in C++ with Qt 4 (Open Publication License) Version control The SVN Book Mercurial: The Definitive Guide Pro Git UNIX / Linux The Art of Unix Programming Linux Device Drivers, Third Edition Others Structure and Interpretation of Computer Programs The Little Book of Semaphores Mathematical Logic - an Introduction An Introduction to the Theory of Computation Developers Developers Developers Developers Linkers and loaders Beej's Guide to Network Programming Maven: The Definitive Guide I will expand on this list as I get comments or when I think of more :D Related: Programming texts and reference material for my Kindle What are some good free programming books? Can anyone recommend a free software engineering book? Edit: Oh I didn't notice the community wiki feature. Feel free to edit your suggestions right in!

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• C# Monte Carlo Incremental Risk Calculation optimisation, random numbers, parallel execution

  - by m3ntat

  My current task is to optimise a Monte Carlo Simulation that calculates Capital Adequacy figures by region for a set of Obligors. It is running about 10 x too slow for where it will need to be in production and number or daily runs required. Additionally the granularity of the result figures will need to be improved down to desk possibly book level at some stage, the code I've been given is basically a prototype which is used by business units in a semi production capacity. The application is currently single threaded so I'll need to make it multi-threaded, may look at System.Threading.ThreadPool or the Microsoft Parallel Extensions library but I'm constrained to .NET 2 on the server at this bank so I may have to consider this guy's port, http://www.codeproject.com/KB/cs/aforge_parallel.aspx. I am trying my best to get them to upgrade to .NET 3.5 SP1 but it's a major exercise in an organisation of this size and might not be possible in my contract time frames. I've profiled the application using the trial of dotTrace (http://www.jetbrains.com/profiler). What other good profilers exist? Free ones? A lot of the execution time is spent generating uniform random numbers and then translating this to a normally distributed random number. They are using a C# Mersenne twister implementation. I am not sure where they got it or if it's the best way to go about this (or best implementation) to generate the uniform random numbers. Then this is translated to a normally distributed version for use in the calculation (I haven't delved into the translation code yet). Also what is the experience using the following? http://quantlib.org http://www.qlnet.org (C# port of quantlib) or http://www.boost.org Any alternatives you know of? I'm a C# developer so would prefer C#, but a wrapper to C++ shouldn't be a problem, should it? Maybe even faster leveraging the C++ implementations. I am thinking some of these libraries will have the fastest method to directly generate normally distributed random numbers, without the translation step. Also they may have some other functions that will be helpful in the subsequent calculations. Also the computer this is on is a quad core Opteron 275, 8 GB memory but Windows Server 2003 Enterprise 32 bit. Should I advise them to upgrade to a 64 bit OS? Any links to articles supporting this decision would really be appreciated. Anyway, any advice and help you may have is really appreciated.

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• How can I reliably check client identity whilst making DCOM calls to a C# .Net 3.5 Server?

  - by pionium

  Hi, I have an old Win32 C++ DCOM Server that I am rewriting to use C# .Net 3.5. The client applications sit on remote XP machines and are also written in C++. These clients must remain unchanged, hence I must implement the interfaces on new .Net objects. This has been done, and is working successfully regarding the implementation of the interfaces, and all of the calls are correctly being made from the old clients to the new .Net objects. However, I'm having problems obtaining the identity of the calling user from the DCOM Client. In order to try to identify the user who instigated the DCOM call, I have the following code on the server... [DllImport("ole32.dll")] static extern int CoImpersonateClient(); [DllImport("ole32.dll")] static extern int CoRevertToSelf(); private string CallingUser { get { string sCallingUser = null; if (CoImpersonateClient() == 0) { WindowsPrincipal wp = System.Threading.Thread.CurrentPrincipal as WindowsPrincipal; if (wp != null) { WindowsIdentity wi = wp.Identity as WindowsIdentity; if (wi != null && !string.IsNullOrEmpty(wi.Name)) sCallingUser = wi.Name; } if (CoRevertToSelf() != 0) ReportWin32Error("CoRevertToSelf"); } else ReportWin32Error("CoImpersonateClient"); return sCallingUser; } } private static void ReportWin32Error(string sFailingCall) { Win32Exception ex = new Win32Exception(); Logger.Write("Call to " + sFailingCall + " FAILED: " + ex.Message); } When I get the CallingUser property, the value returned the first few times is correct and the correct user name is identified, however, after 3 or 4 different users have successfully made calls (and it varies, so I can't be more specific), further users seem to be identified as users who had made earlier calls. What I have noticed is that the first few users have their DCOM calls handled on their own thread (ie all calls from a particular client are handled by a single unique thread), and then subsequent users are being handled by the same threads as the earlier users, and after the call to CoImpersonateClient(), the CurrentPrincipal matches that of the initial user of that thread. To Illustrate: User Tom makes DCOM calls which are handled by thread 1 (CurrentPrincipal correctly identifies Tom) User Dick makes DCOM calls which are handled by thread 2 (CurrentPrincipal correctly identifies Dick) User Harry makes DCOM calls which are handled by thread 3 (CurrentPrincipal correctly identifies Harry) User Bob makes DCOM calls which are handled by thread 3 (CurrentPrincipal incorrectly identifies him as Harry) As you can see in this illustration, calls from clients Harry and Bob are being handled on thread 3, and the server is identifying the calling client as Harry. Is there something that I am doing wrong? Are there any caveats or restrictions on using Impersonations in this way? Is there a better or different way that I can RELIABLY achieve what I am trying to do? All help would be greatly appreciated. Regards Andrew

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• .NET 1.0 ThreadPool Question

  - by dotnet-practitioner

  I am trying to spawn a thread to take care of DoWork task that should take less than 3 seconds. Inside DoWork its taking 15 seconds. I want to abort DoWork and transfer the control back to main thread. I have copied the code as follows and its not working. Instead of aborting DoWork, it still finishes DoWork and then transfers the control back to main thread. What am I doing wrong? class Class1 { /// <summary> /// The main entry point for the application. /// </summary> /// private static System.Threading.ManualResetEvent[] resetEvents; [STAThread] static void Main(string[] args) { resetEvents = new ManualResetEvent[1]; int i = 0; resetEvents[i] = new ManualResetEvent(false); ThreadPool.QueueUserWorkItem(new WaitCallback(DoWork),(object)i); Thread.CurrentThread.Name = "main thread"; Console.WriteLine("[{0}] waiting in the main method", Thread.CurrentThread.Name); DateTime start = DateTime.Now; DateTime end ; TimeSpan span = DateTime.Now.Subtract(start); //abort dowork method if it takes more than 3 seconds //and transfer control to the main thread. do { if (span.Seconds < 3) WaitHandle.WaitAll(resetEvents); else resetEvents[0].Set(); end = DateTime.Now; span = end.Subtract(start); }while (span.Seconds < 2); Console.WriteLine(span.Seconds); Console.WriteLine("[{0}] all done in the main method",Thread.CurrentThread.Name); Console.ReadLine(); } static void DoWork(object o) { int index = (int)o; Thread.CurrentThread.Name = "do work thread"; //simulate heavy duty work. Thread.Sleep(15000); //work is done.. resetEvents[index].Set(); Console.WriteLine("[{0}] do work finished",Thread.CurrentThread.Name); } }

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• MediaElement fails after several plays.

  - by basilkot

  Hi! I have a problem with MediaElement control. I've put six MediaElements on my form, then I start them and change played files by timer. After several times, these elements stop playing. Here is the sample XAML: <Grid> <Grid.RowDefinitions> <RowDefinition Height="*" /> <RowDefinition Height="*" /> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition Width="*" /> <ColumnDefinition Width="*" /> <ColumnDefinition Width="*" /> </Grid.ColumnDefinitions> <MediaElement x:Name="element1" UnloadedBehavior="Close" LoadedBehavior="Manual" Grid.Column="0" Grid.Row="0" /> <MediaElement x:Name="element2" UnloadedBehavior="Close" LoadedBehavior="Manual" Grid.Column="1" Grid.Row="0" /> <MediaElement x:Name="element3" UnloadedBehavior="Close" LoadedBehavior="Manual" Grid.Column="2" Grid.Row="0" /> <MediaElement x:Name="element4" UnloadedBehavior="Close" LoadedBehavior="Manual" Grid.Column="0" Grid.Row="1" /> <MediaElement x:Name="element5" UnloadedBehavior="Close" LoadedBehavior="Manual" Grid.Column="1" Grid.Row="1" /> <MediaElement x:Name="element6" UnloadedBehavior="Close" LoadedBehavior="Manual" Grid.Column="2" Grid.Row="1" /> Here is the sample code: // The code below repeats for each MediaElement List<string> playlist1 = new List<string>() { @"file1.wmv", @"file2.wmv", @"file3.wmv", @"file4.wmv" }; DispatcherTimer timer1 = null; int index1 = 0; ... void Window1_Loaded(object sender, RoutedEventArgs e) { timer1 = new DispatcherTimer(); timer1.Tick += new EventHandler(timer1_Elapsed); timer1.Interval = TimeSpan.FromSeconds(10); element1.Source = new Uri(playlist1[index1]); timer1.Start(); element1.Play(); ... } void timer1_Elapsed(object sender, EventArgs e) { Dispatcher.BeginInvoke(DispatcherPriority.Normal, (System.Threading.ThreadStart)delegate() { element1.Stop(); element1.Close(); timer1.Stop(); index1++; if (index1 >= playlist1.Count) { index1 = 0; } element1.Source = new Uri(playlist1[index1]); timer1.Start(); element1.Play(); }); } ... Does anybody have similar problems?

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• Why does my UIActivityIndicatorView only display once?

  - by Schwigg

  I'm developing an iPhone app that features a tab-bar based navigation with five tabs. Each tab contains a UITableView whose data is retrieved remotely. Ideally, I would like to use a single UIActivityIndicatorView (a subview of the window) that is started/stopped during this remote retrieval - once per tab. Here's how I set up the spinner in the AppDelegate: - (void)applicationDidFinishLaunching:(UIApplication *)application { [window addSubview:rootController.view]; activityIndicator = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge]; [activityIndicator setCenter:CGPointMake(160, 200)]; [window addSubview:activityIndicator]; [window makeKeyAndVisible]; } Since my tabs were all performing a similiar function, I created a base class that all of my tabs' ViewControllers inherit from. Here is the method I'm using to do the remote retrieval: - (void)parseXMLFileAtURL:(NSString *)URL { NSAutoreleasePool *apool = [[NSAutoreleasePool alloc] init]; AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate]; NSLog(@"parseXMLFileAtURL started."); [appDelegate.activityIndicator startAnimating]; NSLog(@"appDelegate.activityIndicator: %@", appDelegate.activityIndicator); articles = [[NSMutableArray alloc] init]; NSURL *xmlURL = [NSURL URLWithString:URL]; rssParser = [[NSXMLParser alloc] initWithContentsOfURL:xmlURL]; [rssParser setDelegate:self]; [rssParser setShouldProcessNamespaces:NO]; [rssParser setShouldReportNamespacePrefixes:NO]; [rssParser setShouldResolveExternalEntities:NO]; [rssParser parse]; NSLog(@"parseXMLFileAtURL finished."); [appDelegate.activityIndicator stopAnimating]; [apool release]; } This method is being called by each view controller as follows: - (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; if ([articles count] == 0) { NSString *path = @"http://www.myproject.com/rss1.xml"; [self performSelectorInBackground:@selector(parseXMLFileAtURL:) withObject:path]; } } This works great while the application loads the first tab's content. I'm presented with the empty table and the spinner. As soon as the content loads, the spinner goes away. Strangely, when I click the second tab, the NSLog messages from the -parseXMLFileAtURL: method show up in the log, but the screen hangs on the first tab's view and I do not see the spinner. As soon as the content is done downloading, the second tab's view appears. I suspect this has something to do with threading, with which I'm still becoming acquainted. Am I doing something obviously wrong here?

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• PHP: Can pcntl_alarm() and socket_select() peacefully exist in the same thread?

  - by DWilliams

  I have a PHP CLI script mostly written that functions as a chat server for chat clients to connect to (don't ask me why I'm doing it in PHP, thats another story haha). My script utilizes the socket_select() function to hang execution until something happens on a socket, at which point it wakes up, processes the event, and waits until the next event. Now, there are some routine tasks that I need performed every 30 seconds or so (check of tempbanned users should be unbanned, save user databases, other assorted things). From what I can tell, PHP doesn't have very great multi-threading support at all. My first thought was to compare a timestamp every time the socket generates an event and gets the program flowing again, but this is very inconsistent since the server could very well sit idle for hours and not have any of my cleanup routines executed. I came across the PHP pcntl extensions, and it lets me use assign a time interval for SIGALRM to get sent and a function get executed every time it's sent. This seems like the ideal solution to my problem, however pcntl_alarm() and socket_select() clash with each other pretty bad. Every time SIGALRM is triggered, all sorts of crazy things happen to my socket control code. My program is fairly lengthy so I can't post it all here, but it shouldn't matter since I don't believe I'm doing anything wrong code-wise. My question is: Is there any way for a SIGALRM to be handled in the same thread as a waiting socket_select()? If so, how? If not, what are my alternatives here? Here's some output from my program. My alarm function simply outputs "Tick!" whenever it's called to make it easy to tell when stuff is happening. This is the output (including errors) after allowing it to tick 4 times (there were no actual attempts at connecting to the server despite what it says): [05-28-10 @ 20:01:05] Chat server started on 192.168.1.28 port 4050 [05-28-10 @ 20:01:05] Loaded 2 users from file PHP Notice: Undefined offset: 0 in /home/danny/projects/PHPChatServ/ChatServ.php on line 112 PHP Warning: socket_select(): unable to select [4]: Interrupted system call in /home/danny/projects/PHPChatServ/ChatServ.php on line 116 [05-28-10 @ 20:01:15] Tick! PHP Warning: socket_accept(): unable to accept incoming connection [4]: Interrupted system call in /home/danny/projects/PHPChatServ/ChatServ.php on line 126 [05-28-10 @ 20:01:25] Tick! PHP Warning: socket_getpeername() expects parameter 1 to be resource, boolean given in /home/danny/projects/PHPChatServ/ChatServ.php on line 129 [05-28-10 @ 20:01:25] Accepting socket connection from PHP Notice: Undefined offset: 1 in /home/danny/projects/PHPChatServ/ChatServ.php on line 112 PHP Warning: socket_select(): unable to select [4]: Interrupted system call in /home/danny/projects/PHPChatServ/ChatServ.php on line 116 [05-28-10 @ 20:01:35] Tick! PHP Warning: socket_accept(): unable to accept incoming connection [4]: Interrupted system call in /home/danny/projects/PHPChatServ/ChatServ.php on line 126 [05-28-10 @ 20:01:45] Tick! PHP Warning: socket_getpeername() expects parameter 1 to be resource, boolean given in /home/danny/projects/PHPChatServ/ChatServ.php on line 129 [05-28-10 @ 20:01:45] Accepting socket connection from PHP Notice: Undefined offset: 2 in /home/danny/projects/PHPChatServ/ChatServ.php on line 112

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