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  • Immutable Method Java

    - by Chris Okyen
    In Java, there is the final keyword in lieu of the const keyword in c and c++. In the latter languages their is mutable and immutable methods such as stated in one answer by Johannes Schaub - litb the question how-many-and-which-are-the-uses-of-const-in-ce Use const to tell others methods won't change the logical state of this object. struct SmartPtr { int getCopies() const { return mCopiesMade; } }ptr1; ... int var = ptr.getCopies(); // returns mCopiesMade and is specified that to not modify objects state. How is this performed in Java?

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  • How to display a dependent list box disabled if no child data exist

    - by frank.nimphius
    A requirement on OTN was to disable the dependent list box of a model driven list of value configuration whenever the list is empty. To disable the dependent list, the af:selectOneChoice component needs to be refreshed with every value change of the parent list, which however already is the case as the list boxes are already dependent. When you create model driven list of values as choice lists in an ADF Faces page, two ADF list bindings are implicitly created in the PageDef file of the page that hosts the input form. At runtime, a list binding is an instance of FacesCtrlListBinding, which exposes getItems() as a method to access a list of available child data (java.util.List). Using Expression Language, the list is accessible with #{bindings.list_attribute_name.items} To dynamically set the disabled property on the dependent af:selectOneChoice component, however, you need a managed bean that exposes the following two methods //empty – but required – setter method public void setIsEmpty(boolean isEmpty) {} //the method that returns true/false when the list is empty or //has values public boolean isIsEmpty() {   FacesContext fctx = FacesContext.getCurrentInstance();   ELContext elctx = fctx.getELContext();   ExpressionFactory exprFactory =                          fctx.getApplication().getExpressionFactory();   ValueExpression vexpr =                       exprFactory.createValueExpression(elctx,                         "#{bindings.EmployeeId.items}",                       Object.class);   List employeesList = (List) vexpr.getValue(elctx);                        return employeesList.isEmpty()? true : false;      } If referenced from the dependent choice list, as shown below, the list is disabled whenever it contains no list data <! --  master list --> <af:selectOneChoice value="#{bindings.DepartmentId.inputValue}"                                  label="#{bindings.DepartmentId.label}"                                  required="#{bindings.DepartmentId.hints.mandatory}"                                   shortDesc="#{bindings.DepartmentId.hints.tooltip}"                                   id="soc1" autoSubmit="true">      <f:selectItems value="#{bindings.DepartmentId.items}" id="si1"/> </af:selectOneChoice> <! --  dependent  list --> <af:selectOneChoice value="#{bindings.EmployeeId.inputValue}"                                   label="#{bindings.EmployeeId.label}"                                      required="#{bindings.EmployeeId.hints.mandatory}"                                   shortDesc="#{bindings.EmployeeId.hints.tooltip}"                                   id="soc2" disabled="#{lovTestbean.isEmpty}"                                   partialTriggers="soc1">     <f:selectItems value="#{bindings.EmployeeId.items}" id="si2"/> </af:selectOneChoice>

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  • Designing for an algorithm that reports progress

    - by Stefano Borini
    I have an iterative algorithm and I want to print the progress. However, I may also want it not to print any information, or to print it in a different way, or do other logic. In an object oriented language, I would perform the following solutions: Solution 1: virtual method have the algorithm class MyAlgoClass which implements the algo. The class also implements a virtual reportIteration(iterInfo) method which is empty and can be reimplemented. Subclass the MyAlgoClass and override reportIteration so that it does what it needs to do. This solution allows you to carry additional information (for example, the file unit) in the reimplemented class. I don't like this method because it clumps together two functionalities that may be unrelated, but in GUI apps it may be ok. Solution 2: observer pattern the algorithm class has a register(Observer) method, keeps a list of the registered observers and takes care of calling notify() on each of them. Observer::notify() needs a way to get the information from the Subject, so it either has two parameters, one with the Subject and the other with the data the Subject may pass, or just the Subject and the Observer is now in charge of querying it to fetch the relevant information. Solution 3: callbacks I tend to see the callback method as a lightweight observer. Instead of passing an object, you pass a callback, which may be a plain function, but also an instance method in those languages that allow it (for example, in python you can because passing an instance method will remain bound to the instance). C++ however does not allow it, because if you pass a pointer to an instance method, this will not be defined. Please correct me on this regard, my C++ is quite old. The problem with callbacks is that generally you have to pass them together with the data you want the callback to be invoked with. Callbacks don't store state, so you have to pass both the callback and the state to the Subject in order to find it at callback execution, together with any additional data the Subject may provide about the event is reporting. Question My question is relative to the fact that I need to implement the opening problem in a language that is not object oriented, namely Fortran 95, and I am fighting with my usual reasoning which is based on python assumptions and style. I think that in Fortran the concept is similar to C, with the additional trouble that in C you can store a function pointer, while in Fortran 95 you can only pass it around. Do you have any comments, suggestions, tips, and quirks on this regard (in C, C++, Fortran and python, but also in any other language, so to have a comparison of language features that can be exploited on this regard) on how to design for an algorithm that must report progress to some external entity, using state from both the algorithm and the external entity ?

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  • usb wifi dongle on ubuntu server, cannot install realtek driver RTL 8188cus

    - by Sandro Dzneladze
    I got cheap Ebay wifi dongle from HongKong, Im trying to set it up on my ubuntu server. Occasionally need to move server, so it cannot always be connected to router via lan. Anyhow, usb wifi came with a driver cd. I uploaded files to my home directory and tried to run install script (RTL 8188cus): sudo bash install.sh But I get error: Authentication requested [root] for make driver: make ARCH=x86_64 CROSS_COMPILE= -C /lib/modules/2.6.38-8-server/build M=/home/minime/RTL 8188cus/Linux/driver/rtl8192CU_linux_v2.0.1324.20110126 modules make[1]: Entering directory `/usr/src/linux-headers-2.6.38-8-server' make[1]: *** No rule to make target `8188cus/Linux/driver/rtl8192CU_linux_v2.0.1324.20110126'. Stop. make[1]: Leaving directory `/usr/src/linux-headers-2.6.38-8-server' make: *** [modules] Error 2 Compile make driver error: 2, Please check error Mesg Any ideas what Im doing wrong? There is another driver folder for linux called: RTL 81XX, which doesn't have install.sh at all! I tried to use make command, but I get: make: *** No targets specified and no makefile found. Stop. Any help? this is first time I'm installing driver from source. Im on Ubuntu 11.04 server. lsusb Bus 001 Device 002: ID 0bda:8176 Realtek Semiconductor Corp. lspci -nn 00:00.0 Host bridge [0600]: Intel Corporation N10 Family DMI Bridge [8086:a000] (rev 02) 00:02.0 VGA compatible controller [0300]: Intel Corporation N10 Family Integrated Graphics Controller [8086:a001] (rev 02) 00:1b.0 Audio device [0403]: Intel Corporation N10/ICH 7 Family High Definition Audio Controller [8086:27d8] (rev 02) 00:1c.0 PCI bridge [0604]: Intel Corporation N10/ICH 7 Family PCI Express Port 1 [8086:27d0] (rev 02) 00:1d.0 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB UHCI Controller #1 [8086:27c8] (rev 02) 00:1d.1 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB UHCI Controller #2 [8086:27c9] (rev 02) 00:1d.2 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB UHCI Controller #3 [8086:27ca] (rev 02) 00:1d.3 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB UHCI Controller #4 [8086:27cb] (rev 02) 00:1d.7 USB Controller [0c03]: Intel Corporation N10/ICH 7 Family USB2 EHCI Controller [8086:27cc] (rev 02) 00:1e.0 PCI bridge [0604]: Intel Corporation 82801 Mobile PCI Bridge [8086:2448] (rev e2) 00:1f.0 ISA bridge [0601]: Intel Corporation NM10 Family LPC Controller [8086:27bc] (rev 02) 00:1f.2 IDE interface [0101]: Intel Corporation N10/ICH7 Family SATA IDE Controller [8086:27c0] (rev 02) 00:1f.3 SMBus [0c05]: Intel Corporation N10/ICH 7 Family SMBus Controller [8086:27da] (rev 02) 01:00.0 Ethernet controller [0200]: Atheros Communications Device [1969:1083] (rev c0) sudo lshw description: Desktop Computer product: To Be Filled By O.E.M. (To Be Filled By O.E.M.) vendor: To Be Filled By O.E.M. version: To Be Filled By O.E.M. serial: To Be Filled By O.E.M. width: 64 bits capabilities: smbios-2.6 dmi-2.6 vsyscall64 vsyscall32 configuration: boot=normal chassis=desktop family=To Be Filled By O.E.M. sku=To Be Filled By O.E.M. uuid=00020003-0004-0005-0006-000700080009 *-core description: Motherboard product: AD525PV3 vendor: ASRock physical id: 0 *-firmware description: BIOS vendor: American Megatrends Inc. physical id: 0 version: P1.20 date: 04/01/2011 size: 64KiB capacity: 448KiB capabilities: pci upgrade shadowing cdboot bootselect socketedrom edd int13floppy1200 int13floppy720 int13floppy2880 int5printscreen int9keyboard int14serial int17printer int10video acpi usb ls120boot zipboot biosbootspecification netboot *-cpu description: CPU product: Intel(R) Atom(TM) CPU D525 @ 1.80GHz vendor: Intel Corp. physical id: 4 bus info: cpu@0 version: Intel(R) Atom(TM) CPU D525 @ 1.80GHz serial: To Be Filled By O.E.M. slot: CPUSocket size: 1800MHz capacity: 1800MHz width: 64 bits clock: 200MHz capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx constant_tsc arch_perfmon pebs bts rep_good nopl aperfmperf pni dtes64 monitor ds_cpl tm2 ssse3 cx16 xtpr pdcm movbe lahf_lm configuration: cores=2 enabledcores=2 threads=4 *-cache:0 description: L1 cache physical id: 5 slot: L1-Cache size: 48KiB capacity: 48KiB capabilities: internal write-back data *-cache:1 description: L2 cache physical id: 6 slot: L2-Cache size: 1MiB capacity: 1MiB capabilities: internal write-back unified *-memory description: System Memory physical id: c slot: System board or motherboard size: 2GiB *-bank:0 description: SODIMM DDR2 Synchronous 800 MHz (1.2 ns) product: ModulePartNumber00 vendor: Manufacturer00 physical id: 0 serial: SerNum00 slot: DIMM0 size: 2GiB width: 64 bits clock: 800MHz (1.2ns) *-bank:1 description: DIMM [empty] product: ModulePartNumber01 vendor: Manufacturer01 physical id: 1 serial: SerNum01 slot: DIMM1 *-pci description: Host bridge product: N10 Family DMI Bridge vendor: Intel Corporation physical id: 100 bus info: pci@0000:00:00.0 version: 02 width: 32 bits clock: 33MHz configuration: driver=agpgart-intel resources: irq:0 *-display description: VGA compatible controller product: N10 Family Integrated Graphics Controller vendor: Intel Corporation physical id: 2 bus info: pci@0000:00:02.0 version: 02 width: 32 bits clock: 33MHz capabilities: msi pm vga_controller bus_master cap_list rom configuration: driver=i915 latency=0 resources: irq:41 memory:fea80000-feafffff ioport:dc00(size=8) memory:e0000000-efffffff memory:fe900000-fe9fffff *-multimedia description: Audio device product: N10/ICH 7 Family High Definition Audio Controller vendor: Intel Corporation physical id: 1b bus info: pci@0000:00:1b.0 version: 02 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list configuration: driver=HDA Intel latency=0 resources: irq:43 memory:fea78000-fea7bfff *-pci:0 description: PCI bridge product: N10/ICH 7 Family PCI Express Port 1 vendor: Intel Corporation physical id: 1c bus info: pci@0000:00:1c.0 version: 02 width: 32 bits clock: 33MHz capabilities: pci pciexpress msi pm normal_decode bus_master cap_list configuration: driver=pcieport resources: irq:40 ioport:e000(size=4096) memory:feb00000-febfffff ioport:80000000(size=2097152) *-network description: Ethernet interface product: Atheros Communications vendor: Atheros Communications physical id: 0 bus info: pci@0000:01:00.0 logical name: eth0 version: c0 serial: XX size: 100Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress vpd bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=atl1c driverversion=1.0.1.0-NAPI duplex=full firmware=N/A ip=192.168.1.99 latency=0 link=yes multicast=yes port=twisted pair speed=100Mbit/s resources: irq:42 memory:febc0000-febfffff ioport:ec00(size=128) *-usb:0 description: USB Controller product: N10/ICH 7 Family USB UHCI Controller #1 vendor: Intel Corporation physical id: 1d bus info: pci@0000:00:1d.0 version: 02 width: 32 bits clock: 33MHz capabilities: uhci bus_master configuration: driver=uhci_hcd latency=0 resources: irq:23 ioport:d880(size=32) *-usb:1 description: USB Controller product: N10/ICH 7 Family USB UHCI Controller #2 vendor: Intel Corporation physical id: 1d.1 bus info: pci@0000:00:1d.1 version: 02 width: 32 bits clock: 33MHz capabilities: uhci bus_master configuration: driver=uhci_hcd latency=0 resources: irq:19 ioport:d800(size=32) *-usb:2 description: USB Controller product: N10/ICH 7 Family USB UHCI Controller #3 vendor: Intel Corporation physical id: 1d.2 bus info: pci@0000:00:1d.2 version: 02 width: 32 bits clock: 33MHz capabilities: uhci bus_master configuration: driver=uhci_hcd latency=0 resources: irq:18 ioport:d480(size=32) *-usb:3 description: USB Controller product: N10/ICH 7 Family USB UHCI Controller #4 vendor: Intel Corporation physical id: 1d.3 bus info: pci@0000:00:1d.3 version: 02 width: 32 bits clock: 33MHz capabilities: uhci bus_master configuration: driver=uhci_hcd latency=0 resources: irq:16 ioport:d400(size=32) *-usb:4 description: USB Controller product: N10/ICH 7 Family USB2 EHCI Controller vendor: Intel Corporation physical id: 1d.7 bus info: pci@0000:00:1d.7 version: 02 width: 32 bits clock: 33MHz capabilities: pm debug ehci bus_master cap_list configuration: driver=ehci_hcd latency=0 resources: irq:23 memory:fea77c00-fea77fff *-pci:1 description: PCI bridge product: 82801 Mobile PCI Bridge vendor: Intel Corporation physical id: 1e bus info: pci@0000:00:1e.0 version: e2 width: 32 bits clock: 33MHz capabilities: pci subtractive_decode bus_master cap_list *-isa description: ISA bridge product: NM10 Family LPC Controller vendor: Intel Corporation physical id: 1f bus info: pci@0000:00:1f.0 version: 02 width: 32 bits clock: 33MHz capabilities: isa bus_master cap_list configuration: latency=0 *-ide description: IDE interface product: N10/ICH7 Family SATA IDE Controller vendor: Intel Corporation physical id: 1f.2 bus info: pci@0000:00:1f.2 logical name: scsi0 version: 02 width: 32 bits clock: 66MHz capabilities: ide pm bus_master cap_list emulated configuration: driver=ata_piix latency=0 resources: irq:19 ioport:1f0(size=8) ioport:3f6 ioport:170(size=8) ioport:376 ioport:ff90(size=16) memory:80200000-802003ff *-disk description: ATA Disk product: WDC WD10TPVT-11U vendor: Western Digital physical id: 0.0.0 bus info: scsi@0:0.0.0 logical name: /dev/sda version: 01.0 serial: WD-WXC1A80P0314 size: 931GiB (1TB) capabilities: partitioned partitioned:dos configuration: ansiversion=5 signature=00088c47 *-volume:0 description: EXT4 volume vendor: Linux physical id: 1 bus info: scsi@0:0.0.0,1 logical name: /dev/sda1 logical name: /media/private version: 1.0 serial: 042daf2d-350c-4640-a76a-4554c9d98c59 size: 300GiB capacity: 300GiB capabilities: primary journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized configuration: created=2011-11-06 11:05:03 filesystem=ext4 label=Private lastmountpoint=/media/private modified=2012-04-13 20:01:16 mount.fstype=ext4 mount.options=rw,relatime,barrier=1,stripe=1,data=ordered mounted=2012-04-13 20:01:16 state=mounted *-volume:1 description: Extended partition physical id: 2 bus info: scsi@0:0.0.0,2 logical name: /dev/sda2 size: 625GiB capacity: 625GiB capabilities: primary extended partitioned partitioned:extended *-logicalvolume:0 description: Linux filesystem partition physical id: 5 logical name: /dev/sda5 logical name: /media/storage capacity: 600GiB configuration: mount.fstype=ext4 mount.options=rw,relatime,barrier=1,stripe=1,data=ordered state=mounted *-logicalvolume:1 description: Linux filesystem partition physical id: 6 logical name: /dev/sda6 logical name: /media/dropbox capacity: 24GiB configuration: mount.fstype=ext4 mount.options=rw,relatime,barrier=1,stripe=1,data=ordered state=mounted *-volume:2 description: EXT4 volume vendor: Linux physical id: 3 bus info: scsi@0:0.0.0,3 logical name: /dev/sda3 logical name: /media/www version: 1.0 serial: 9b0a27b4-05d8-40d5-bfc7-4aeba198db7b size: 2570MiB capacity: 2570MiB capabilities: primary journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized configuration: created=2011-11-06 11:05:11 filesystem=ext4 label=www lastmountpoint=/media/www modified=2012-04-15 11:31:12 mount.fstype=ext4 mount.options=rw,relatime,barrier=1,stripe=1,data=ordered mounted=2012-04-15 11:31:12 state=mounted *-volume:3 description: Linux swap volume physical id: 4 bus info: scsi@0:0.0.0,4 logical name: /dev/sda4 version: 1 serial: 6ed1130e-3aad-4fa6-890b-77e729121e3b size: 4098MiB capacity: 4098MiB capabilities: primary nofs swap initialized configuration: filesystem=swap pagesize=4096 *-serial UNCLAIMED description: SMBus product: N10/ICH 7 Family SMBus Controller vendor: Intel Corporation physical id: 1f.3 bus info: pci@0000:00:1f.3 version: 02 width: 32 bits clock: 33MHz configuration: latency=0 resources: ioport:400(size=32) *-scsi physical id: 1 bus info: usb@1:4 logical name: scsi2 capabilities: emulated scsi-host configuration: driver=usb-storage *-disk description: SCSI Disk physical id: 0.0.0 bus info: scsi@2:0.0.0 logical name: /dev/sdb size: 3864MiB (4051MB) capabilities: partitioned partitioned:dos configuration: signature=000b4c55 *-volume description: EXT4 volume vendor: Linux physical id: 1 bus info: scsi@2:0.0.0,1 logical name: /dev/sdb1 logical name: / version: 1.0 serial: 33926e39-4685-4f63-b83c-f2a67824b69a size: 3862MiB capacity: 3862MiB capabilities: primary bootable journaled extended_attributes large_files huge_files dir_nlink recover extents ext4 ext2 initialized configuration: created=2011-10-11 14:03:46 filesystem=ext4 lastmountpoint=/ modified=2012-03-19 11:47:29 mount.fstype=ext4 mount.options=rw,noatime,errors=remount-ro,barrier=1,data=ordered mounted=2012-04-15 11:31:11 state=mounted rfkill list all Doesnt show anything! dmesg | grep -i firmware [ 0.715481] pci 0000:00:1f.0: [Firmware Bug]: TigerPoint LPC.BM_STS cleared

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  • Can't Install php5-msql

    - by user210445
    Hello friends I'm finishing the process of installing Apache/Php/mysql installations but this shows up: # sudo apt-get install mysql-server php5-msql Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package php5-msql After some adjustments this happened: angel@Voix:~$ sudo apt-get install mysql-server php5-mysql Reading package lists... Done Building dependency tree Reading state information... Done mysql-server is already the newest version. php5-mysql is already the newest version. The following packages were automatically installed and are no longer required: gir1.2-ubuntuoneui-3.0 libubuntuoneui-3.0-1 thunderbird-globalmenu Use 'apt-get autoremove' to remove them. The following extra packages will be installed: mysql-server-5.5 Suggested packages: tinyca mailx The following packages will be upgraded: mysql-server-5.5 1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 4 not fully installed or removed. Need to get 0 B/8,827 kB of archives. After this operation, 32.7 MB of additional disk space will be used. Do you want to continue [Y/n]? debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable (Reading database ... dpkg: warning: files list file for package `mysql-server-5.5' missing, assuming package has no files currently installed. (Reading database ... 172971 files and directories currently installed.) Preparing to replace mysql-server-5.5 5.5.34-0ubuntu0.12.04.1 (using .../mysql-server-5.5_5.5.34-0ubuntu0.12.04.1_amd64.deb) ... debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error processing /var/cache/apt/archives/mysql-server-5.5_5.5.34-0ubuntu0.12.04.1_amd64.deb (--unpack): subprocess new pre-installation script returned error exit status 1 debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error while cleaning up: subprocess new post-removal script returned error exit status 1 Errors were encountered while processing: /var/cache/apt/archives/mysql-server-5.5_5.5.34-0ubuntu0.12.04.1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1) angel@Voix:~$ sudo apt-get install mysql-server-5.5 Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: gir1.2-ubuntuoneui-3.0 libubuntuoneui-3.0-1 thunderbird-globalmenu Use 'apt-get autoremove' to remove them. Suggested packages: tinyca mailx The following packages will be upgraded: mysql-server-5.5 1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 4 not fully installed or removed. Need to get 0 B/8,827 kB of archives. After this operation, 32.7 MB of additional disk space will be used. debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable (Reading database ... dpkg: warning: files list file for package `mysql-server-5.5' missing, assuming package has no files currently installed. (Reading database ... 172971 files and directories currently installed.) Preparing to replace mysql-server-5.5 5.5.34-0ubuntu0.12.04.1 (using .../mysql-server-5.5_5.5.34-0ubuntu0.12.04.1_amd64.deb) ... debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error processing /var/cache/apt/archives/mysql-server-5.5_5.5.34-0ubuntu0.12.04.1_amd64.deb (--unpack): subprocess new pre-installation script returned error exit status 1 debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error while cleaning up: subprocess new post-removal script returned error exit status 1 Errors were encountered while processing: /var/cache/apt/archives/mysql-server-5.5_5.5.34-0ubuntu0.12.04.1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1) angel@Voix:~$ sudo apt-get install mysql-server php5-mysql Reading package lists... Done Building dependency tree Reading state information... Done mysql-server is already the newest version. php5-mysql is already the newest version. The following packages were automatically installed and are no longer required: gir1.2-ubuntuoneui-3.0 libubuntuoneui-3.0-1 thunderbird-globalmenu Use 'apt-get autoremove' to remove them. The following extra packages will be installed: mysql-server-5.5 Suggested packages: tinyca mailx The following packages will be upgraded: mysql-server-5.5 1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. 4 not fully installed or removed. Need to get 0 B/8,827 kB of archives. After this operation, 32.7 MB of additional disk space will be used. Do you want to continue [Y/n]? y debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable (Reading database ... dpkg: warning: files list file for package `mysql-server-5.5' missing, assuming package has no files currently installed. (Reading database ... 172971 files and directories currently installed.) Preparing to replace mysql-server-5.5 5.5.34-0ubuntu0.12.04.1 (using .../mysql-server-5.5_5.5.34-0ubuntu0.12.04.1_amd64.deb) ... debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error processing /var/cache/apt/archives/mysql-server-5.5_5.5.34-0ubuntu0.12.04.1_amd64.deb (--unpack): subprocess new pre-installation script returned error exit status 1 debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable dpkg: error while cleaning up: subprocess new post-removal script returned error exit status 1 Errors were encountered while processing: /var/cache/apt/archives/mysql-server-5.5_5.5.34-0ubuntu0.12.04.1_amd64.deb E: Sub-process /usr/bin/dpkg returned an error code (1)

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  • What's the best way to manage list item sort order with Drag & Drop UI?

    - by Reddy S R
    I have a list of Students that I should display to user on a web page in tabular format. The items are stored in DB along with SortOrder information. On the web page, user can rearrange the list order by dragging and dropping the items to their desired sort order, similar to this post. Below is a screenshot of my test page. In the above example, each row has sort order info attached to it. When I drop John Doe (Student Id 10) above the Student Id 1 row, the list order should now be: 2, 10, 1, 8, 11. What's the optimistic (less resource hungry) way to store and update Sort Order information? My only idea for now is, for every change in the list's sort order, every object's SortOrder value should be updated, which in my opinion is very resource hungry. Just FYI: I might have at most 25 rows in my table.

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  • Sharepoint Expiration Policy not working

    - by spano
    I have a Sharepoint 2010 list with a custom content type with an associated retention policy. The policy consists of a custom formula and then the Send to Recycle Bin action. However, I realized that the items were not being deleted. I verified the list settings and the retention policy was configured: I run the Expiration Policy job several times but no items were deleted and no errors found in the logs. I also added logging to the custom formula but no logging was found neither. Finally, I found...(read more)

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  • Stateless layout switching in Ubuntu 14.04

    - by ulidtko
    I use extensively two keyboard layouts (latin for English, and cyrillic for Ukrainian and Russian), and it bothers me to experience my mode errors because of the additional bit of UI state: the current layout. I used to eliminate them completely by using stateless layout switching, whereby one has no next layout action (as such an action is based on the current state, which is easy to forget for the user, and so leads to errors), rather only two actions: enable latin layout; enable cyrillic layout. This was trivially accomplishable in pre-Saucy releases. As illustrated on the screenshot above. However, that settings window was destroyed in Saucy. How do I get my stateless switching now?

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  • Build Dependencies and Silverlight 4

    - by Kyle Burns
    At my current position, I’ve been doing quite a bit of Silverlight development and have also been working with TFS2010 build services to enable continuous integration.  One of the critical pieces of a successful continuous build setup (and also one of the benefits of having one) is that the build system should be able to “get latest” against the source repository and immediately build with no errors.  This can break down both in an automated build scenario and a “new guy” scenario when the solution has external dependencies that may not be present in the build environment. The method that I use to address the dependency issue is to store all of the binaries upon which my solution depends in a folder under the solution root called “Reference Items”.  I keep this folder as part of the solution and check all of the binaries into source control so when I get the latest version of the solution from source control all of the binaries are downloaded to my machine as well and gets me closer to the ideal where a new developer installs the development IDE, get latest and can immediately build and run unit tests before jumping into coding the feature of the day. This all sounds pretty good (and it is), but a little while back I ran into one of those little hiccups that requires a little manual intervention.  The issue that I ran into is that with Silverlight (at least version 4), the behavior of the “Add Reference” command when adding reference to a DLL that is present in the GAC is to omit the HintPath element that it includes with regular .Net projects, so even if the DLL is setting in the Reference Items folder and downloaded to the build machine it cannot be found at compile time and the build will fail. To work around this behavior, you need to be comfortable editing the XML project files generated by Visual Studio (in my case this is typically a .csproj file).  Simply open the project file in your favorite text editor, find the Reference element that refers to the component, and modify the XML to include the HintPath.  Here’s a before and after example of the component that ultimately led me to the investigation behind this post: Before: <Reference Include="Telerik.Windows.Controls, Version=2011.2.920.1040, Culture=neutral, PublicKeyToken=5803cfa389c90ce7, processorArchitecture=MSIL" /> After: <Reference Include="Telerik.Windows.Controls, Version=2011.2.920.1040, Culture=neutral, PublicKeyToken=5803cfa389c90ce7, processorArchitecture=MSIL">       <HintPath>..\Reference Items\Telerik.Windows.Controls.dll</HintPath>     </Reference>

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  • Stop Saying "Multi-Channel!"

    - by David Dorf
    I keep hearing the term "multi-channel" in our industry, but its time to move on. It kinda reminds me of the term "ECR" or electronic cash register. Long ago ECR was a leading-edge term, but nowadays its rarely used because its table-stakes. After all, what cash register today isn't electronic? The same logic applies to multi-channel, at least when we're talking about tier-1 and tier-2 retailers. If you're still talking about multi-channel retailing, you're in big trouble. Some have switched over to the term "cross-channel," and that's a step in the right direction but still falls short. Its kinda like saying, "I upgraded my ECR to accept debit cards!" Yawn. Who hasn't? Today's retailers need to focus on omni-channel, which I first heard from my friends over at RSR but was originally coined at IDC. First retailers added e-commerce to their store and catalog channels yielding multi-channel retailing. Consumers could use the channel that worked best for them. Then some consumers wanted to combine channels with features like buy-on-the-Web, pickup-in-the-store. Thus began the cross-channel initiatives to breakdown the silos and enable the channels to communicate with each other. But the multi-channel architecture is full of duplication that thwarts efforts of providing a consistent experience. Each has its own cart, its own pricing, and often its own CRM. This was an outcrop of trying to bring the independent channels to market quickly. Rather than reusing and rebuilding existing components to meet the new demands, silos were created that continue to exist today. Today's consumers want omni-channel retailing. They want to interact with brands in a consistent manner that is channel transparent, yet optimized for that particular interaction. The diagram below, from the soon-to-be-released NRF Mobile Blueprint v2, shows this progression. For retailers to provide an omni-channel experience, there needs to be one logical representation of products, prices, promotions, and customers across all channels. The only thing that varies is the presentation of the content based on the delivery mechanism (e.g. shelf labels, mobile phone, web site, print, etc.) and often these mechanisms can be combined in various ways. I'm looking forward to the day in which I can use my phone to scan QR-codes in a catalog to create a shopping cart of items. Then do some further research on the retailer's Web site and be told about related items that might interest me. Be able to easily solicit opinions and reviews from social sites, and finally enter the store to pickup my items, knowing that any applicable coupons have been applied. In this scenario, I the consumer are dealing with a single brand that is aware of me and my needs throughout the entire transaction. Nirvana.

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  • Implementing a FSM with ActionScript 2 without using classes?

    - by Up2u
    I have seen several references of A.I. and FSM, but sadly I still can't understand the point of an FSM in AS2.0. Is it a must to create a class for each state? I have a game-project which also it has an A.I., the A.I. has 3 states: distanceCheck, ChaseTarget, and Hit the target. It's an FPS game and played via mouse. I have created the A.I. successfully, but I want to convert it to FSM method... My first state is CheckDistanceState() and in that function I look for the nearest target and trigger the function ChaseState(), there I insert the Hit() function to destroy the enemy, The 3 functions that I created are being called in AI_cursor.onEnterframe. Is there any chance to implement an FSM without the need to create a class? From what I've read before, you have to create a class. I prefer to write the code on frames in flash and I still don't understand how to have external classes.

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  • ScreenManagement how do I had different controls?

    - by DiasFrancisco
    I saw a question here using DataTemplates with WPF for ScreenManagement, I was curious and I gave it a try I think the ideia is amazing and very clean. Though I'm new to WPF and I read a lot of times that almost everything should be made in XAML and very little should be "coded behind". My questions resolves about using the datatemplate ideia, WHERE should the code that calls the transitions be? where should I define which commands are avaiable in which screens. For example: [ScreenA] Commands: Pressing B - Goes to state B Pressing ESC - Exits [ScreenB] Commands: Pressing A - Goes to state A Pressing SPACE - Exits where do I define the keyEventHandlers? and where do I call the next screen? I'm doing this as an hobby for learning and "if you are learning, better learn it right" :) Thank you for your time.

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  • Should custom data elements be stored as XML or database entries?

    - by meteorainer
    There are a ton of questions like this, but they are mostly very generalized, so I'd like to get some views on my specific usage. General: I'm building a new project on my own in Django. It's focus will be on small businesses. I'd like to make it somewhat customizble for my clients so they can add to their customer/invoice/employee/whatever items. My models would reflect boilerplate items that all ModelX might have. For example: first name last name email address ... Then my user's would be able to add fields for whatever data they might like. I'm still in design phase and am building this myself, so I've got some options. Working on... Right now the 'extra items' models have a FK to the generic model (Customer and CustomerDataPoints for example). All values in the extra data points are stored as char and will be coerced/parced into their actual format at view building. In this build the user could theoretically add whatever values they want, group them in sets and generally access them at will from the views relavent to that model. Pros: Low storage overhead, very extensible, searchable Cons: More sql joins My other option is to use some type of markup, or key-value pairing stored directly onto the boilerplate models. This coul essentially just be any low-overhead method weather XML or literal strings. The view and form generated from the stored data would be taking control of validation and reoganizing on updates. Then it would just dump the data back in as a char/blob/whatever. Something like: <datapoint type='char' value='something' required='true' /> <datapoint type='date' value='01/01/2001' required='false' /> ... Pros: No joins needed, Updates for validation and views are decoupled from data Cons: Much higher storage overhead, limited capacity to search on extra content So my question is: If you didn't live in the contraints impose by your company what method would you use? Why? What benefits or pitfalls do you see down the road for me as a small business trying to help other small businesses? Just to clarify, I am not asking about custom UI elements, those I can handle with forms and template snippets. I'm asking primarily about data storage and retreival of non standardized data relative to a boilerplate model.

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  • America The Vulnerable

    - by Naresh Persaud
    At the Executive Edge this week, Joel Brenner shared his perspective on the state of cyber-security. Today our most critical military and corporate secrets are under attack. In his presentation, Joel shared his perspective on how organizations can can better prepare for the changing security climate. The amount of state sponsored espionage has highlighted weaknesses in our national security infrastructure. The Internet was primarily intended to provide a means of collaboration for non-commercial entities. Today it is the backbone of our digital commerce and digital experience and it was not designed to secure the activities and data we share today.  Check out "America The Vulnerable" and learn more. 

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  • CentOS - Configuring Puppet to play nice with SELinux

    - by Mike Purcell
    I am running into an issue every time I attempt to start the puppetmasterd service, for which I receive the following error message: root@service1 ~ # -> /etc/init.d/puppetmaster start Starting puppetmaster: Could not prepare for execution: Got 1 failure(s) while initializing: change from absent to directory failed: Could not set 'directory on ensure: Permission denied - /etc/puppet/ssl [FAILED] Apparently there was a known issue with this scenario as outlined in this bug report, however in the bug report it states the issue has been resolved in selinux-policy-3.9.16-29.fc15, but the latest CentOS default upstream version is 3.7.19-155.el6_3.4. So I am trying to figure out the best solution. I can either create a local security policy to allow puppetmasterd the access it needs, or keep researching and install a newer version of selinux-policy outside of the default upstream channel. Anyone have any recommendations? Please don't recommend disabling SELinux... ----- Update ----- Here is the puppet.conf: [main] # The Puppet log directory. # The default value is '$vardir/log'. logdir = /var/log/puppet # Where Puppet PID files are kept. # The default value is '$vardir/run'. rundir = /var/run/puppet # Where SSL certificates are kept. # The default value is '$confdir/ssl'. ssldir = $vardir/ssl [master] certname=puppetmaster.ownij.lan dns_alt_names=puppetmaster.ownij.lan [agent] # The file in which puppetd stores a list of the classes # associated with the retrieved configuratiion. Can be loaded in # the separate ``puppet`` executable using the ``--loadclasses`` # option. # The default value is '$confdir/classes.txt'. classfile = $vardir/classes.txt # Where puppetd caches the local configuration. An # extension indicating the cache format is added automatically. # The default value is '$confdir/localconfig'. localconfig = $vardir/localconfig server=puppetmaster.ownij.lan And here are the denials per the audit log: type=AVC msg=audit(1349751364.985:666): avc: denied { search } for pid=15093 comm="puppetmasterd" name="/" dev=dm-2 ino=2 scontext=unconfined_u:system_r:puppetmaster_t:s0 tcontext=system_u:object_r:home_root_t:s0 tclass=dir type=SYSCALL msg=audit(1349751364.985:666): arch=c000003e syscall=4 success=no exit=-13 a0=1391420 a1=7fffef09ed10 a2=7fffef09ed10 a3=120c500 items=0 ppid=15092 pid=15093 auid=500 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts1 ses=13 comm="puppetmasterd" exe="/usr/bin/ruby" subj=unconfined_u:system_r:puppetmaster_t:s0 key=(null) type=AVC msg=audit(1349751365.302:667): avc: denied { search } for pid=15093 comm="puppetmasterd" name="/" dev=dm-2 ino=2 scontext=unconfined_u:system_r:puppetmaster_t:s0 tcontext=system_u:object_r:home_root_t:s0 tclass=dir type=SYSCALL msg=audit(1349751365.302:667): arch=c000003e syscall=4 success=no exit=-13 a0=1d18530 a1=7fffef0d04d0 a2=7fffef0d04d0 a3=8 items=0 ppid=15092 pid=15093 auid=500 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts1 ses=13 comm="puppetmasterd" exe="/usr/bin/ruby" subj=unconfined_u:system_r:puppetmaster_t:s0 key=(null) type=AVC msg=audit(1349751365.465:668): avc: denied { search } for pid=15093 comm="puppetmasterd" name="/" dev=dm-2 ino=2 scontext=unconfined_u:system_r:puppetmaster_t:s0 tcontext=system_u:object_r:home_root_t:s0 tclass=dir type=SYSCALL msg=audit(1349751365.465:668): arch=c000003e syscall=4 success=no exit=-13 a0=1af3930 a1=7fffef0c5c70 a2=7fffef0c5c70 a3=8 items=0 ppid=15092 pid=15093 auid=500 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts1 ses=13 comm="puppetmasterd" exe="/usr/bin/ruby" subj=unconfined_u:system_r:puppetmaster_t:s0 key=(null) type=AVC msg=audit(1349751365.467:669): avc: denied { search } for pid=15093 comm="puppetmasterd" name="/" dev=dm-2 ino=2 scontext=unconfined_u:system_r:puppetmaster_t:s0 tcontext=system_u:object_r:home_root_t:s0 tclass=dir type=SYSCALL msg=audit(1349751365.467:669): arch=c000003e syscall=4 success=no exit=-13 a0=1b17aa0 a1=7fffef0c5c70 a2=7fffef0c5c70 a3=8 items=0 ppid=15092 pid=15093 auid=500 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts1 ses=13 comm="puppetmasterd" exe="/usr/bin/ruby" subj=unconfined_u:system_r:puppetmaster_t:s0 key=(null) type=AVC msg=audit(1349751366.401:670): avc: denied { write } for pid=15093 comm="puppetmasterd" name="puppet" dev=dm-0 ino=132035 scontext=unconfined_u:system_r:puppetmaster_t:s0 tcontext=system_u:object_r:puppet_etc_t:s0 tclass=dir type=SYSCALL msg=audit(1349751366.401:670): arch=c000003e syscall=83 success=no exit=-13 a0=2d7a400 a1=1f9 a2=2d7a40f a3=7fffef0a6df0 items=0 ppid=15092 pid=15093 auid=500 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts1 ses=13 comm="puppetmasterd" exe="/usr/bin/ruby" subj=unconfined_u:system_r:puppetmaster_t:s0 key=(null) And the audit log if I pass through audit2allow: root@service1 ~ # -> fgrep puppetmasterd /var/log/audit/audit.log | audit2allow -m puppetmasterd module puppetmasterd 1.0; require { type home_root_t; type puppetmaster_t; type puppet_etc_t; type puppet_var_run_t; type httpd_sys_content_t; class lnk_file { relabelfrom relabelto }; class file { relabelfrom read getattr open }; class dir { write read search getattr setattr }; } #============= puppetmaster_t ============== allow puppetmaster_t home_root_t:dir { search getattr }; allow puppetmaster_t httpd_sys_content_t:dir read; allow puppetmaster_t httpd_sys_content_t:file { read getattr open }; #!!!! The source type 'puppetmaster_t' can write to a 'dir' of the following types: # puppet_log_t, puppet_var_lib_t, puppet_var_run_t, puppetmaster_tmp_t allow puppetmaster_t puppet_etc_t:dir { write setattr }; allow puppetmaster_t puppet_etc_t:lnk_file { relabelfrom relabelto }; allow puppetmaster_t puppet_var_run_t:file relabelfrom;

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  • Ubuntu 12.04, can't find my home wifi network

    - by Anton
    I've tried several solutions I found on the web, but didn't manage to solve a problem. Since today my laptop won't find my WiFi network, but neighbours' networks are suggested. Another laptop with U12.04 does find one. What do I do? I've Dell Latitude-E4310, 02:00.0 Network controller: Broadcom Corporation BCM4313 802.11bgn Wireless Network Adapter (rev 01) Subsystem: Dell Inspiron M5010 / XPS 8300 Flags: bus master, fast devsel, latency 0, IRQ 17 Memory at f2c00000 (64-bit, non-prefetchable) [size=16K] Capabilities: <access denied> Kernel driver in use: brcmsmac Kernel modules: bcma, brcmsmac also NetworkManager Tool State: connected (global) - Device: eth1 ----------------------------------------------------------------- Type: 802.11 WiFi Driver: wl State: disconnected Default: no HW Address: 1C:65:9D:7A:45:5C Capabilities: Wireless Properties WEP Encryption: yes WPA Encryption: yes WPA2 Encryption: yes Should I provide anything else? Many thanks in advance.

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  • Install 32-bit gstreamer plugins on 64-bit

    - by Rua
    I am trying to install the 32-bit gstreamer plugins on my 64-bit system (Ubuntu 12.10 based). I can install the packages gstreamer0.10-plugins-base:i386 and gstreamer0.10-plugins-good:i386. However, gstreamer0.10-plugins-bad:i386, gstreamer0.10-plugins-bad-multiverse:i386 and gstreamer0.10-plugins-ugly:i386 conflict with 64-bit packages already installed on my system: $ sudo apt-get install gstreamer0.10-plugins-bad:i386 Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: gstreamer0.10-plugins-bad:i386 : Depends: libass4:i386 (>= 0.9.7) but it is not going to be installed Depends: libdca0:i386 but it is not going to be installed Depends: libdvdnav4:i386 (>= 4.2.0+20120524) but it is not going to be installed Depends: libdvdread4:i386 but it is not going to be installed Depends: libslv2-9:i386 (>= 0.6.4-1~) but it is not going to be installed E: Unable to correct problems, you have held broken packages. ... $ sudo apt-get install gstreamer0.10-plugins-bad-multiverse:i386 Reading package lists... Done Building dependency tree Reading state information... Done The following extra packages will be installed: libavcodec53:i386 libavutil51:i386 libfaac0:i386 libfaad2:i386 libgsm1:i386 libmjpegtools-1.9:i386 libmp3lame0:i386 libquicktime2:i386 libschroedinger-1.0-0:i386 libswscale2:i386 libva1:i386 libvpx1:i386 libx264-123:i386 libxvidcore4:i386 The following packages will be REMOVED: gstreamer0.10-plugins-bad-multiverse libfaac0 libmjpegtools-1.9 mint-meta-codecs The following NEW packages will be installed: gstreamer0.10-plugins-bad-multiverse:i386 libavcodec53:i386 libavutil51:i386 libfaac0:i386 libfaad2:i386 libgsm1:i386 libmjpegtools-1.9:i386 libmp3lame0:i386 libquicktime2:i386 libschroedinger-1.0-0:i386 libswscale2:i386 libva1:i386 libvpx1:i386 libx264-123:i386 libxvidcore4:i386 0 upgraded, 15 newly installed, 4 to remove and 5 not upgraded. Need to get 9,198 kB of archives. After this operation, 23.3 MB of additional disk space will be used. Do you want to continue [Y/n]? ... $ sudo apt-get install gstreamer0.10-plugins-ugly:i386 Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: gstreamer0.10-plugins-ugly:i386 : Depends: libdvdread4:i386 but it is not going to be installed E: Unable to correct problems, you have held broken packages. This means that I can't play mp3s (among other things) in 32-bit applications that use gstreamer. Is there a way around this?

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  • Scrum for Team System v3 RTM available

    - by Enrique Lima
    If you are using the Scrum for Team System (aka Conchango Scrum Template), it has hit RTM and it is available for download.  First you will need to register and then you will ne able to access the goods. There is also a very well laid out Getting Started with v3 guide, put together by Crispin Parker. Note:  Very important to know and consider, is the fact there is no upgrade or migration strategy laid out from v2.2.  So you are left to your own devices on that one.  There are plenty of discussions going on as far as making it happen.  Don’t get me wrong v2.2 work items will be present and you will be able to use them, just don’t expect the v3 template to trigger when  adding new work items. For now, get TFS in place, install the template and start fresh.  The Workbench should be released soon too, and that makes it a great component to this solution.

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  • C# - How to detect all IP addresses from a LAN?

    - by SAMIR BHOGAYTA
    string strHostName = string.Empty; cmbIPAddress.Items.Clear(); // Getting Ip address of local machine... // First get the host name of local machine. strHostName = Dns.GetHostName(); // Then using host name, get the IP address list.. IPHostEntry ipEntry = Dns.GetHostByName(strHostName); IPAddress[] iparrAddr = ipEntry.AddressList; if (iparrAddr.Length 0) { for (int intLoop = 0; intLoop cmbIPAddress.Items.Add(iparrAddr[intLoop].ToString()); }

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  • How to work with scenes in a 2D game

    - by Anearion
    I'm a java/android programmer, but I don't have any experience in game programming, I'm already reading proper books, like "Pro Android Games", but my concerns are more about the ideas behind game programming than the techniques themselves. I'm working on a 2D game, something like Cluedo to let you understand the genre. I would like to know how should I act with the "scenes", for example, a room with a desk, TV, windows and a lamp. I need to make some items tappable and others not. Is it common to use one image (invisible to the user) with every different item a different color, then call the getColor() method on the image? Or use one image as background, and separate images for all the items? If the latter, how can I set the positioning? and should I use imageView or imageButton? I'm sorry if those are really low quality questions, but as "outsider" ( I'm 23 and still finishing my university ) it's pretty hard learn alone.

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  • How to write a network game? [closed]

    - by Tom Wijsman
    Based on Why is so hard to develop a MMO?: Networked game development is not trivial; there are large obstacles to overcome in not only latency, but cheat prevention, state management and load balancing. If you're not experienced with writing a networked game, this is going to be a difficult learning exercise. I know the theory about sockets, servers, clients, protocols, connections and such things. Now I wonder how one can learn to write a network game: How to balance load problems? How to manage the game state? How to keep things synchronized? How to protect the communication and client from reverse engineering? How to work around latency problems? Which things should be computed local and which things on the server? ... Are there any good books, tutorials, sites, interesting articles or other questions regarding this? I'm looking for broad answers, but specific ones are fine too to learn the difference.

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  • How to properly do weapon cool-down reload timer in multi-player laggy environment?

    - by John Murdoch
    I want to handle weapon cool-down timers in a fair and predictable way on both client on server. Situation: Multiple clients connected to server, which is doing hit detection / physics Clients have different latency for their connections to server ranging from 50ms to 500ms. They want to shoot weapons with fairly long reload/cool-down times (assume exactly 10 seconds) It is important that they get to shoot these weapons close to the cool-down time, as if some clients manage to shoot sooner than others (either because they are "early" or the others are "late") they gain a significant advantage. I need to show time remaining for reload on player's screen Clients can have clocks which are flat-out wrong (bad timezones, etc.) What I'm currently doing to deal with latency: Client collects server side state in a history, tagged with server timestamps Client assesses his time difference with server time: behindServerTimeNs = (behindServerTimeNs + (System.nanoTime() - receivedState.getServerTimeNs())) / 2 Client renders all state received from server 200 ms behind from his current time, adjusted by what he believes his time difference with server time is (whether due to wrong clocks, or lag). If he has server states on both sides of that calculated time, he (mostly LERP) interpolates between them, if not then he (LERP) extrapolates. No other client-side prediction of movement, e.g., to make his vehicle seem more responsive is done so far, but maybe will be added later So how do I properly add weapon reload timers? My first idea would be for the server to send each player the time when his reload will be done with each world state update, the client then adjusts it for the clock difference and thus can estimate when the reload will be finished in client-time (perhaps considering also for latency that the shoot message from client to server will take as well?), and if the user mashes the "shoot" button after (or perhaps even slightly before?) that time, send the shoot event. The server would get the shoot event and consider the time shot was made as the server time when it was received. It would then discard it if it is nowhere near reload time, execute it immediately if it is past reload time, and hold it for a few physics cycles until reload is done in case if it was received a bit early. It does all seem a bit convoluted, and I'm wondering whether it will work (e.g., whether it won't be the case that players with lower ping get better reload rates), and whether there are more elegant solutions to this problem.

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