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  • Finding the time to program in your spare time?

    - by Omar Kooheji
    I've got about a dozen programming projects bouncing about my head, and I'd love to contribute to some open source projects, the problem I have is that having spent the entire day staring at Visual Studio and or Eclipse (Sometimes both at the same time...) the last thing I feel like doing when I go home is program. How do you build up the motivation/time to work on your own projects after work? I'm not saying that I don't enjoy programming, it's just that I enjoy other things to and it can be hard to even do something you enjoy if you've spent all day already doing it. I think that if I worked at a chocolate factory the last thing I'd want to see when I got home was a Wonka bar.

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  • Next in Concurrency

    - by Jatin
    For past year I have been working a lot on concurrency in Java and have build and worked on many concurrent packages. So in terms of development in the concurrent world, I am quite confident. Further I am very much interested to learn and understand more about concurrent programming. But I am unable to answer myself what next? What extra should I learn or work on to inherit more skills related to Multi-core processing. If there is any nice book (read and enjoyed 'concurrency in practice' and 'concurrent programming in java') or resource's related to Multi-core processing so that I can go to the next level?

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  • Linux Books For Windows/C++ Programmers?

    - by John Dibling
    I'm a Windows C++ programmer with a great deal of experience, and I'm looking for book recommendations to get up to speed with programming in Linux (specifically RHE 6). Ideally, I'd like a book geared specifically to my needs. Something along the lines of "Linux C++ Programming for Windows Experts" would be nice. :) I'm open to any recommendations you have. My domain is primarily financial market data servers (no GUIs) and simple console apps. I do a lot of multithreading, a lot of networking, not a lot of user interface stuff. I know C++0x, but our production codebase can only use C++. Thanks for your recommendations for books and/or resources!

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  • Windows Storage Server 2003 R2 RDP Disconnection

    - by Antitribu
    I am unable to remote desktop to our Windows Storage Server 2003 R2 machine. There are a few people about with similar issues but no answers around. Symantec End Point is installed but no network protection. Using rdesktop in Linux I receive: ERROR: send: Connection reset by peer NOT IMPLEMENTED: PDU 12 ERROR: Connection closed Where the "PDU XX" number changes on each connection. In windows using the latest mstsc I receive: The connection was lost due to a network error. Try connecting again. If the problem persists, contact your network Administrator. Any ideas?

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  • What's the most important trait of a programmer desired by peer programmers [closed]

    - by greengit
    Questions here talk about most important programming skills someone is supposed to possess, and, a lot of great answers spring up. The answers and the questioners seem mostly interested on qualities related to getting a better job, nailing some interview, things desired by boss or management, or improving your programming abilities. One thing that often gets blown over is the genuine consideration for what traits peers want. They don't much value things like you're one of those 'gets things done' people for the company, or you never miss a deadline, or your code is least painful to review and debug, or you're team player with fantastic leading abilities. They probably care more if you're helpful, are a refreshing person to talk to, you're fun to program in pair with, everybody wants you to review their code, or something of that nature. I, for one, would care that I come off to my peers as a pleasurable programmer to work with, as much as I care about my impression on my boss or management. Is this really significant, and if yes, what are the most desirable traits peers want from each other.

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  • What are best practices when giving a presentation to programmers?

    - by blunders
    I've watched 50 plus presentations on programming topics, although most have been online; example, Google Tech Talks -- and have ad-hoc experience on what formats work for programmers, or practices to take into account when presenting to a group of programmers. That said, I'm open to any suggestions, but here's some topic of the top of my head: Programming Jokes, Images, etc. Posting Code for download Contact Info Collecting feedback Presenting Code on Screen If it matters, in this case -- I'm giving a presentation on using a scripting language to extract, transform and load data to a local user group who's focus is the scripting language; Ruby in this case. Questions, feedback, requests -- just comment, thanks!!

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  • Rip authedicatation from LDAP to Local

    - by oxinabox
    We are taking a small portion of out network offline, and running a separate network using that portion. (By small portion I mean 2 servers, that will be connected to 30 odd boxs that aren't usually part of our network, and don't need to authenicate) I intend to create a VM on one of the servers to provide general user services, and IRC server, remote shell etc. And I would like the users to be able to use there usual server log in details. Problem is the LDAP server that normally checks those details is not one of the severs. So I need to be able to some how take their details off LDAP and put them on the the server that is coming. One suggestion I had was to set a LDAP server on the VM locally, and clone the LDAP database onto it (using something called slapcat) is this the best way? Or can I I change the LDAP data into local authentication data?

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  • Need assistance setting up Linux Router with 2 public lans

    - by user195407
    I was assigned a.b.c.10/30 (Public IP) for my router and given a.b.c.9 as the gateway. I was also assigned x.y.z.128/25 (Public IP block) for my use. I want to setup a Linux router to handle this situation. My Linux box has 3 NICs, eth0 is a.b.c.10, eth1 I have assigned x.y.z.254, eth2 is unused at present. I have eth1 connected to a network switch, and several devices connected. Let's say box A is x.y.z.129 with a gateway of x.y.z.254. I have not connected to the network yet, as it is not live. What settings do I need to make, beyond adding the 2 network definitions to the cards and having "route add default gw a.b.c.9 eth0"? I may add a private 192.168.100.0/24 lan to eth2 later.

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  • Adopting Technologies for the Sake of Technologies

    - by shiju
    Unlike other engineering industries, the software engineering industry is really lacking maturity. The lack of maturity can see in different aspects of entire software development life cycle. I think other engineering industries are well organised and structured with common, proven engineering practices. The software engineering industry is greatly a diverse industry with different operating systems, and variety of development platforms, programming languages, frameworks and tools. Now these days, people are going behind the hypes and intellectual thoughts without understanding their core business problems and adopting technologies and practices for the sake of technologies and practices and simply becoming a “poster child” of technologies and practices. Understanding the core business problem and providing best, solid solution with a platform neutral approach, will give you more business values and ROI, instead of blindly adopting technologies and tailor-made your applications for the sake of technologies and practices. People have been simply migrating their solutions in favour of new technologies and different versions of frameworks without any business need. The “Pepsi Challenge” in the Software Development  Pepsi Challenge marketing campaign of the 1980s was a popular and very interesting marketing promotion in which people taste one cup of Pepsi and another cup with Coca Cola. In the taste test, more than 50% of people were preferred Pepsi  over Coca Cola. The success story behind the Pepsi was more sweetness contains in the Pepsi cola. They have simply added more sugar and more people preferred more sweet flavour. You can’t simply identify the better one after sipping one cup of cola based on the sweetness which contains. These things have been happening in the software industry for choosing development frameworks and technologies. People have been simply choosing frameworks based on the initial sugary feeling without understanding its core strengths and weakness. The sugary framework might be more harmful when you develop real-world systems. There is not any silver bullet for solving all kind of problems and frameworks and tools do have strengths and weakness. So it would be better to understand their strength and weakness. And please keep in mind that you have to develop real apps to understand the real capabilities and weakness of a framework. Evaluating a technology based on few blog posts will harm your projects and these bloggers might be lacking real-world experience with the framework. The Problem with Align a Development Practice with Tools Recently I have observed a discussion in a group where one guy asked suggestions for practicing Continuous Delivery (CD) as part of the agile based application engineering. Then the discussion quickly went to using and choosing a Continuous Integration (CI) tool and different people suggested different Continuous Integration (CI) tools for simply practicing Continuous Delivery. If you have worked with core agile engineering practices, you could clearly know that the real essence of agile is neither choosing a tool nor choosing a process. By simply choosing CI tool from a particular vendor will not ensure that you are delivering an evolving software based on customer feedback. You have to understand the real essence of a engineering practice and choose a right tool for practicing it instead of simply focus on a particular tool for a practicing an development practice. If you want to adopt a practice, you need a solid understanding on it with its real essence where tools are just helping us for better automation. Adopting New Technologies for the Sake of Technologies The another problem is that developers have been a tendency to adopt new technologies and simply migrating their existing apps to new technologies. It is okay if your existing system is having problem  with a technology stack or or maintainability challenge with existing solution, and moving to new technology for solving the current problems. We have been adopting new technologies for solving new challenges like solving the scalability challenges when the application or user bases is growing unpredictably. Please keep in mind that all new technologies will become old after working with it for few years. The below Facebook status update of Janakiraman, expresses the attitude of a typical customer. For an example, Node.js is becoming a hottest buzzword in the software industry and many developers are trying to adopt Node.js for their apps. The important thing is that Node.js is a minimalist framework that does some great things for some problems, but it’s not a silver bullet. I have been also working with Node.js which is good for some problems, but really bad for choosing it for all kind of problems. By adopting new technologies for new projects is good if we could get real business values from it because newer framework would solve some existing well known problems and provide better solutions where it can incorporate good solutions for the latest challenges . But adopting a new technology for the sake of new technology is really bad idea. Another example is JavaScript is getting lot of attention so that lot of developers are developing heavy JavaScript centric web apps. First, they will adopt a client-side JavaScript MV* framework from AngularJS, Ember, Backbone etc, and develop a Single Page App(SPA) where they are repeating the mistakes we did in the past with server-side. The mistakes we did in the server-side is transforming to client-side. The problem is that people are just adopting new technologies, but not improving their solutions. I predict that many Single Page App will suck in the future. We need a hybrid approach where we should be able to leverage both server-side and client-side for developing next-generation web apps. The another problem is that if you like a particular framework, use it for all kind of apps. In the past, I know some Silverlight passionate guys were tried to use that framework for all kind of apps including larger line of business apps. And these days developers are migrating their existing Silverlight apps in favour of HTML5 buzzword. So the real question is, what is the business values we are getting from these apps when we are developing it for the sake of a particular technology instead of business need. The another problem is that our solutions consultants are trying to provide unnecessary solutions for the sake of a particular technology or for a hype. For an example, Big Data solutions are great for solving the problem of three Vs : volume, velocity and variety. But trying to put this for every application will make problems. Let’s say, there is a small web site running with limited budget and saying that we need a recommendation engine for the web site with a Hadoop based solution with a 16 node cluster, would be really horrible. If we really need a Hadoop based solution, got for it, but trying to put this for all application would be a big disaster. It would be great if could understand the core business problems first, and later choose a right framework for providing solutions for the actual business problem, instead of trying to provide so many solutions. The Problem with Tied Up to a Platform Vendor Some organizations and teams are tied up with a particular platform vendor where they don’t want to use any product other than their preferred or existing platform vendor. They will accept any product provided by the vendor regardless of its capability. This will lets you some benefits regards with integration and collaboration of different products provided by the same vendor, but it will loose your opportunity to provide better solution for your business problems. For a real world sample scenario, lot of companies have been using SAP for their ERP solutions. When they are thinking about mobility or thinking about developing hybrid mobile apps, they can easily find out a framework from SAP. SAP provides a framework for HTML 5 based UI development named SAPUI5. If you are simply adopting that framework only based for the preference of existing platform vendor, you might be loose different opportunities for providing better solution. Initially you might enjoy the sugary feeling provided by the platform vendor, but you have to think about developing apps which should be capable for solving future challenges. I am not saying that any framework is not good and I believe that all frameworks are good over another one for solving at least one problem. My point is that we should not tied up with any specific platform vendor unless your organization is having resource availability problems. Being Polyglot for Providing Right Solutions The modern software engineering industry is greatly diverse with different tools and platforms. Lot of open source frameworks and new programming languages have been releasing to the developer community, where choosing the right platform without any biased opinion, is really a difficult task. But it would really great if we could develop an attitude with platform neutral mindset and being a polyglot developer for providing better solutions based on the actual business problems. IMHO, we should learn a new programming language and a new framework every year. This will improve the quality of our developer capabilities and also improve the quality of our primary programming language skills. Being polyglot for individual developers and organizational teams will give you greater opportunity to your developer experience and also for your applications. Organizations can analyse their business problem without tied with any technology and later they can provide solutions by choosing different platform and tools. Summary    In this blog post, what I was trying to say that we should not tied up or biased with any development platform, technology, vendor or programming language and we should not adopt technologies and practices for the sake of technologies. If we are adopting a technology or a practice for the sake of it, we are simply becoming a “poster child” of the technology and practice. We should not become a poster child of other people’s intellectual thoughts and theories, instead of it we should become solutions developers and solutions consultants where we should be able to provide better solutions for the business problems. Being a polyglot developer is a good idea for improving your developer skills which lets you provide better solutions for the business problems. The most important thing is that we should become platform neutral developers where our passion should be for providing brilliant solutions. It would be great if we could provide minimalist, pragmatic business solutions. You can follow me on Twitter @shijucv

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  • iptables forward rule not working in openwrt

    - by Udit Gupta
    I am trying to apply some iptables forwarding rules in openwrt. Here is my scenario - My server has two cards ath0 and br-lan. br-lan is connected to internet and ath0 to private network. The other m/c in n/w also has ath0 that connects with this server's ath0 and they are able to ping each other. Now, I want other m/c in network to use internet using br-lan of server so I thought of using iptables forwarding rule- Here is what I tried - Server : $ ping 1.1.1.6 // <ath0-ip of client> works fine $ iptables -A FORWARD -i ath0 -o br-lan -j ACCEPT $ /etc/init.d/firewall restart Client : $ ping 1.1.1.5 // <ath0-ip of server> works fine $ ping 132.245.244.60 // <br-lan ip of server> (not working) I am new to iptables stuff and openwrt. What I am doing wrong here ?? Any other help if anyone could suggest for my scenario Edit- m/c - machine n/w - network

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  • auto-summarization: classful vs classless routing protocols

    - by yorble
    Suppose a router R1 is directly connected to the following subnets: 10.1.0.0/24 10.1.1.0/24 10.1.2.0/24 10.1.3.0/24 If it is running RIPv1, it will advertise: "i have the network 10.0.0.0" (implicitly understood by receiving RIPv1 routers as 10.0.0.0/8 because the protocol is classful) but suppose we changed the routing protocol to RIPv2 and turned ON auto-summarization. Would it behave in the same way? Would it advertise: "i have the network 10.0.0.0" (advertised WITHOUT subnet mask, and implicitly understood by other routers as 10.0.0.0/8) OR would it auto-summarize in a non classful way like: "i have 10.1.0.0/22" (advertised as network id and subnet mask pair) In other words, does turning on auto-summarization in RIPv2 (or other classless routing protocols) cause it to auto-summarize in a classful manner or simply auto-summarize classlessly to the best of its ability?

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  • C# books for the experienced programmer

    - by Michael Dmitry Azarkevich
    So I've been programming in C# for 3 years now (been programming in various languages for 3 years before that as well) and most of the stuff I learned I pieced together on the internet. The thing is, I want to understand C# more formally and in depth and so would like to get some books on the subjects. Any books you'd recommend? Also, I've heard good things about "C# 4.0 in a Nutshell", "Pro C# 2010 and the .NET 4 Platform" and "CLR via C#". What do you think of these? (The people at stackoverflow told me to take it here. Please, Please tell me I'm in the right place this time)

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  • Is Information Technology really Engineering?

    - by RPK
    While travelling I met a mathematician who was sitting near me. In a discussion he said: "...there is nothing like engineering in IT or rather programming". A true engineering is what Architecture is, what Electrical and Mechanical is. It made me think and I was puzzled. A percent of my brain agreed also because in Indian Army, there is no subject like Computer Engineering in the Engineering Corps. They don't consider programming as engineering. This is what I heard few years back, I don't know what Indian Army thinks now. What are your views?

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  • vSphere ESX 5.5 hosts cannot connect to NFS Server

    - by Gerald
    Summary: My problem is I cannot use the QNAP NFS Server as an NFS datastore from my ESX hosts despite the hosts being able to ping it. I'm utilising a vDS with LACP uplinks for all my network traffic (including NFS) and a subnet for each vmkernel adapter. Setup: I'm evaluating vSphere and I've got two vSphere ESX 5.5 hosts (node1 and node2) and each one has 4x NICs. I've teamed them all up using LACP/802.3ad with my switch and then created a distributed switch between the two hosts with each host's LAG as the uplink. All my networking is going through the distributed switch, ideally, I want to take advantage of DRS and the redundancy. I have a domain controller VM ("Central") and vCenter VM ("vCenter") running on node1 (using node1's local datastore) with both hosts attached to the vCenter instance. Both hosts are in a vCenter datacenter and a cluster with HA and DRS currently disabled. I have a QNAP TS-669 Pro (Version 4.0.3) (TS-x69 series is on VMware Storage HCL) which I want to use as the NFS server for my NFS datastore, it has 2x NICs teamed together using 802.3ad with my switch. vmkernel.log: The error from the host's vmkernel.log is not very useful: NFS: 157: Command: (mount) Server: (10.1.2.100) IP: (10.1.2.100) Path: (/VM) Label (datastoreNAS) Options: (None) cpu9:67402)StorageApdHandler: 698: APD Handle 509bc29f-13556457 Created with lock[StorageApd0x411121] cpu10:67402)StorageApdHandler: 745: Freeing APD Handle [509bc29f-13556457] cpu10:67402)StorageApdHandler: 808: APD Handle freed! cpu10:67402)NFS: 168: NFS mount 10.1.2.100:/VM failed: Unable to connect to NFS server. Network Setup: Here is my distributed switch setup (JPG). Here are my networks. 10.1.1.0/24 VM Management (VLAN 11) 10.1.2.0/24 Storage Network (NFS, VLAN 12) 10.1.3.0/24 VM vMotion (VLAN 13) 10.1.4.0/24 VM Fault Tolerance (VLAN 14) 10.2.0.0/24 VM's Network (VLAN 20) vSphere addresses 10.1.1.1 node1 Management 10.1.1.2 node2 Management 10.1.2.1 node1 vmkernel (For NFS) 10.1.2.2 node2 vmkernel (For NFS) etc. Other addresses 10.1.2.100 QNAP TS-669 (NFS Server) 10.2.0.1 Domain Controller (VM on node1) 10.2.0.2 vCenter (VM on node1) I'm using a Cisco SRW2024P Layer-2 switch (Jumboframes enabled) with the following setup: LACP LAG1 for node1 (Ports 1 through 4) setup as VLAN trunk for VLANs 11-14,20 LACP LAG2 for my router (Ports 5 through 8) setup as VLAN trunk for VLANs 11-14,20 LACP LAG3 for node2 (Ports 9 through 12) setup as VLAN trunk for VLANs 11-14,20 LACP LAG4 for the QNAP (Ports 23 and 24) setup to accept untagged traffic into VLAN 12 Each subnet is routable to another, although, connections to the NFS server from vmk1 shouldn't need it. All other traffic (vSphere Web Client, RDP etc.) goes through this setup fine. I tested the QNAP NFS server beforehand using ESX host VMs atop of a VMware Workstation setup with a dedicated physical NIC and it had no problems. The ACL on the NFS Server share is permissive and allows all subnet ranges full access to the share. I can ping the QNAP from node1 vmk1, the adapter that should be used to NFS: ~ # vmkping -I vmk1 10.1.2.100 PING 10.1.2.100 (10.1.2.100): 56 data bytes 64 bytes from 10.1.2.100: icmp_seq=0 ttl=64 time=0.371 ms 64 bytes from 10.1.2.100: icmp_seq=1 ttl=64 time=0.161 ms 64 bytes from 10.1.2.100: icmp_seq=2 ttl=64 time=0.241 ms Netcat does not throw an error: ~ # nc -z 10.1.2.100 2049 Connection to 10.1.2.100 2049 port [tcp/nfs] succeeded! The routing table of node1: ~ # esxcfg-route -l VMkernel Routes: Network Netmask Gateway Interface 10.1.1.0 255.255.255.0 Local Subnet vmk0 10.1.2.0 255.255.255.0 Local Subnet vmk1 10.1.3.0 255.255.255.0 Local Subnet vmk2 10.1.4.0 255.255.255.0 Local Subnet vmk3 default 0.0.0.0 10.1.1.254 vmk0 VM Kernel NIC info ~ # esxcfg-vmknic -l Interface Port Group/DVPort IP Family IP Address Netmask Broadcast MAC Address MTU TSO MSS Enabled Type vmk0 133 IPv4 10.1.1.1 255.255.255.0 10.1.1.255 00:50:56:66:8e:5f 1500 65535 true STATIC vmk0 133 IPv6 fe80::250:56ff:fe66:8e5f 64 00:50:56:66:8e:5f 1500 65535 true STATIC, PREFERRED vmk1 164 IPv4 10.1.2.1 255.255.255.0 10.1.2.255 00:50:56:68:f5:1f 1500 65535 true STATIC vmk1 164 IPv6 fe80::250:56ff:fe68:f51f 64 00:50:56:68:f5:1f 1500 65535 true STATIC, PREFERRED vmk2 196 IPv4 10.1.3.1 255.255.255.0 10.1.3.255 00:50:56:66:18:95 1500 65535 true STATIC vmk2 196 IPv6 fe80::250:56ff:fe66:1895 64 00:50:56:66:18:95 1500 65535 true STATIC, PREFERRED vmk3 228 IPv4 10.1.4.1 255.255.255.0 10.1.4.255 00:50:56:72:e6:ca 1500 65535 true STATIC vmk3 228 IPv6 fe80::250:56ff:fe72:e6ca 64 00:50:56:72:e6:ca 1500 65535 true STATIC, PREFERRED Things I've tried/checked: I'm not using DNS names to connect to the NFS server. Checked MTU. Set to 9000 for vmk1, dvSwitch and Cisco switch and QNAP. Moved QNAP onto VLAN 11 (VM Management, vmk0) and gave it an appropriate address, still had same issue. Changed back afterwards of course. Tried initiating the connection of NAS datastore from vSphere Client (Connected to vCenter or directly to host), vSphere Web Client and the host's ESX Shell. All resulted in the same problem. Tried a path name of "VM", "/VM" and "/share/VM" despite not even having a connection to server. I plugged in a linux system (10.1.2.123) into a switch port configured for VLAN 12 and tried mounting the NFS share 10.1.2.100:/VM, it worked successfully and I had read-write access to it I tried disabling the firewall on the ESX host esxcli network firewall set --enabled false I'm out of ideas on what to try next. The things I'm doing differently from my VMware Workstation setup is the use of LACP with a physical switch and a virtual distributed switch between the two hosts. I'm guessing the vDS is probably the source of my troubles but I don't know how to fix this problem without eliminating it.

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  • Apache server in raspberry PI not visible from outside( public IP)

    - by Kronos
    I have made a fresh install of Arch Linux ARM into a Raspberry PI and I mounted there a LAMP, all fresh. I have another Arch(x86) in my laptop with Apache also there, and as far as I know, two web servers cannot run in the same network segment so, the problem is as follows. I my laptop, having Apache running, if I enter via the public ip of my network everything turns ok and I can see my website but, (obviously turning this server down) if I enter from the public IP with the Apache running in the raspberry pi( yes, only that Apache running) i cannot see my website in there. Also, if I access via local network it is a normal success, I can see my website. So, I can enter my raspberry website only via local but in my other web server i can enter it via local and public. I have the same conf files in both of them so what is the difference? I was planning in making the rpi as a development server. Thanks in advance

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  • RemoteApp cannot connect to webapp

    - by user58505
    I have just set up a Server 2008 R2 machine with Remote Desktop Services. It's all running on the one server, just for a single application, which works fine locally and when using Remote Desktop Web Access on the local network. However, when accessing it over the Internet, you can log on to RD Web Access fine, but when running the RemoteApp you get the message: RemoteApp Disconnected The remote computer could not be found. Please contact your helpdesk about this error. The application and all Remote Desktop services are on a single machine. I have purchased and installed a GoDaddy Cert. It works like a charm in the local network, but I get the above message when trying to access through rdweb How can I enable the RemoteApp to function outside the local network? I think there is one or 2 steps I left out??.. Please help...

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  • Which statically typed languages support intersection types for function return values?

    - by stakx
    Initial note: This question got closed after several edits because I lacked the proper terminology to state accurately what I was looking for. Sam Tobin-Hochstadt then posted a comment which made me recognise exactly what that was: programming languages that support intersection types for function return values. Now that the question has been re-opened, I've decided to improve it by rewriting it in a (hopefully) more precise manner. Therefore, some answers and comments below might no longer make sense because they refer to previous edits. (Please see the question's edit history in such cases.) Are there any popular statically & strongly typed programming languages (such as Haskell, generic Java, C#, F#, etc.) that support intersection types for function return values? If so, which, and how? (If I'm honest, I would really love to see someone demonstrate a way how to express intersection types in a mainstream language such as C# or Java.) I'll give a quick example of what intersection types might look like, using some pseudocode similar to C#: interface IX { … } interface IY { … } interface IB { … } class A : IX, IY { … } class B : IX, IY, IB { … } T fn() where T : IX, IY { return … ? new A() : new B(); } That is, the function fn returns an instance of some type T, of which the caller knows only that it implements interfaces IX and IY. (That is, unlike with generics, the caller doesn't get to choose the concrete type of T — the function does. From this I would suppose that T is in fact not a universal type, but an existential type.) P.S.: I'm aware that one could simply define a interface IXY : IX, IY and change the return type of fn to IXY. However, that is not really the same thing, because often you cannot bolt on an additional interface IXY to a previously defined type A which only implements IX and IY separately. Footnote: Some resources about intersection types: Wikipedia article for "Type system" has a subsection about intersection types. Report by Benjamin C. Pierce (1991), "Programming With Intersection Types, Union Types, and Polymorphism" David P. Cunningham (2005), "Intersection types in practice", which contains a case study about the Forsythe language, which is mentioned in the Wikipedia article. A Stack Overflow question, "Union types and intersection types" which got several good answers, among them this one which gives a pseudocode example of intersection types similar to mine above.

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  • Are there any non-self-taught famous programmers? [closed]

    - by Jon Purdy
    It seems to me that being a self-taught programmer has significant advantages over picking it up only in higher education. Not only does a self-taught developer have a headstart on their 10 000-odd hours of mastery, but their hobby demonstrates genuine interest. This will likely lead to a process of continuous self-improvement over their career, not to mention increased likelihood of producing personal projects that are worthy of fame. A programmer who spends four years in study (not nearly all of which is going to be directly concerned with programming) has far less leisure to explore and learn independently than does a developer who starts college with even a few years of dedicated hobbyist study. I wonder whether there are any famed developers who had no exposure to programming before deciding to study it in university. I simply doubt that an 18-year-old has the capacity to become a brilliant programmer with no prior experience, but that seems like an awfully elitist and unpleasant view, so I'd like to be proven wrong.

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  • What happened to HTML table tags?

    - by John
    I started to code HTML in 1998, and in that time I was used to code a lot table tags, playing with tr and td, I learned many things analysing the source code of many portals on the internet with notepad and Microsoft FrontPage, the latter, aw, how many tables overlapping others, it was fun, I loved that time. However, I abandoned web programming for almost seven years and this year I decided to see what's the web programming today likes. Completely different, there are not table tags anymore, it's full of div and span tags. Why happened ? What are these new tags and why nobody codes in table tags anymore ?

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  • Can't the NetworkManager applet to appear in the Gnome panel in Ubuntu

    - by Nate
    I have researched this problem extensively and I can't seem to find an answer. In Ubuntu 10.04 LTS, I want to connect to my VPN through the NetworkManager applet. I installed all the network manager packages, including the gnome client. I understand I need to add the "Notification Area" to the panel, which I have done. I checked that the NetworkManager is running: nate@nate-desktop:~$ service network-manager status network-manager start/running, process 763 In /etc/NetworkManager/nm-system-settings.conf, I have added managed=true (don't know if this matters, but I saw it suggested on one forum): nate@nate-desktop:~$ more /etc/NetworkManager/nm-system-settings.conf # This file is installed into /etc/NetworkManager, and is loaded by # NetworkManager by default. To override, specify: '--config file' # during NM startup. This can be done by appending to DAEMON_OPTS in # the file: # # /etc/default/NetworkManager # [main] plugins=ifupdown,keyfile [ifupdown] #managed=false managed=true At this point, it looks like NetworkManager is running but it's not appearing in the NotificationArea of the panel. I don't know what else to try. Any ideas?

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  • Can't the NetworkManager applet to appear in the Gnome panel in Ubuntu

    - by Nate
    I have researched this problem extensively and I can't seem to find an answer. In Ubuntu 10.04 LTS, I want to connect to my VPN through the NetworkManager applet. I installed all the network manager packages, including the gnome client. I understand I need to add the "Notification Area" to the panel, which I have done. I checked that the NetworkManager is running: nate@nate-desktop:~$ service network-manager status network-manager start/running, process 763 In /etc/NetworkManager/nm-system-settings.conf, I have added managed=true (don't know if this matters, but I saw it suggested on one forum): nate@nate-desktop:~$ more /etc/NetworkManager/nm-system-settings.conf # This file is installed into /etc/NetworkManager, and is loaded by # NetworkManager by default. To override, specify: '--config file' # during NM startup. This can be done by appending to DAEMON_OPTS in # the file: # # /etc/default/NetworkManager # [main] plugins=ifupdown,keyfile [ifupdown] #managed=false managed=true At this point, it looks like NetworkManager is running but it's not appearing in the NotificationArea of the panel. I don't know what else to try. Any ideas?

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  • C# Adds Optional and Named Arguments

    Earlier this month Microsoft released Visual Studio 2010, the .NET Framework 4.0 (which includes ASP.NET 4.0), and new versions of their core programming languages: C# 4.0 and Visual Basic 10. In designing the latest versions of C# and VB, Microsoft has worked to bring the two languages into closer parity. Certain features available in C# were missing in VB, and vice-a-versa. Last week I wrote about <a href="http://www.4guysfromrolla.com/articles/042110-1.aspx">Visual Basic 2010's language enhancements</a>, which include implicit line continuation, auto-implemented properties, and collection initializers - three useful features that were available in previous versions of C#. Similarly, C# 4.0 introduces new features to the C# programming language that were

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  • Homework with allocate subnet IP address

    - by Don Lun
    I'm having difficulty solving a subnet allocation homework problem. Assume that a university has an address block 128.205.224.0/19. It has to allocate addresses for 2 departments' networks, each of size 1800, and for 4 offices, of sizes 550, 600, 650, and 750 nodes respectively. Assuming that the university network allocates addresses sequentially from the beginning of the allocated allocated address space, what are the prefix allocations for these subnetworks? I first thought in this way: There should be 6 subnets in the network. So I need 3 bits for the subnets. So 3 + 19 = 22 bits should be the network bits. Then there are only 10 bits left. 2^10 = 1024 < 1800, so this cannot work. Could you guys give me a hint or some thoughts for solving this problem?

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