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  • Routing between 2 different subnets on 2 different interfaces in SonicOS

    - by Chris1499
    I'm having a bit of a problem allowing traffic between two of my subnets. Here's the structure I've built. The X0 interface has our windows server on it and it handles DHCP/DNS, etc. X1 has the WAN connection. The Sonicwall is handling DHCP on X2. The X3 interface is connected to a different vlan on the 48 port switch. The Sonicwall is handling DHCP on this network as well. So here's what i want to do. The network on X2 is for our guest wireless; i don't want it to be able to access any of the other networks, just the internet, so i that all blocked in the firewall. No issues there. The X3 network is going to be for programmable controllers, and needs to be able to access the X0 network where our computers are. This is where my problem is. I'm not able to get between the 192.168.2.xxx and the 192.168.1.xxx on interfaces X0 and X3 respectively. I have these rules set up in the firewall. The Lan Primary Subnet is the 192.168.2.0 on X0. So if i'm not mistaken, this will allow traffic between the two through the firewall. Now this is where I'm a little confused. Do i need to use NAT to get the traffic from X0 to go to X3 (and vice versa), or a static route, or both? Currently i have both, though i doubt they're done correctly (also in screenshot). I've tried to ping between the two without luck. Any advice, or if you see what's wrong with my setup, is much appreciated. If you need some more information, let me know. Thanks all! EDIT: So i found that i don't neither either NAT or a static route, that the setting in the firewall is enough. I can now ping from the 192.168.1.xxx network, however i can't access the server on the 192.168.2.xxx network. When i try to access i get "An error occured while reconnecting to Z: to server Microsoft Windows Network: The local device name is already in use. This connection has not been restored. What am i missing?

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  • Any consumer routers with Outgoing VPN support?

    - by Brian Lacy
    When I'm working at home, I need to be able to connect to three different outgoing VPNs, two of which happen to use the same internal IP addressing schemes (192.168.0.*). I also need a static address for my VirtualBox VM so I can connect to my testing web server. Are there any routers which will allow me to connect to multiple outgoing VPNs and assign different internal IP addresses through NAT? Is such a thing even possible, or are there alternate solutions available? Thanks!

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  • Is there a decent diagram of packet flow for a modern era (2.6+) iptables setup?

    - by stsquad
    I'm currently trying to debug a particularly hairy set of DNAT based iptables rules (the UDP reply never makes it back to the original requester) and I'm struggling to visualise the packet flow through all the numerous tables involved. So far Google'ing has shown me old 2.4 based ipchains ones. The netfilter site has some good text docs but is short on diagrams and a number of the external links are now dead. So is there a canonical diagram for iptables packet flow, preferably showing how NAT/Masqueraded packets are also dealt with?

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  • How to Upload Really Large Files to SkyDrive, Dropbox, or Email

    - by Matthew Guay
    Do you need to upload a very large file to store online or email to a friend? Unfortunately, whether you’re emailing a file or using online storage sites like SkyDrive, there’s a limit on the size of files you can use. Here’s how to get around the limits. Skydrive only lets you add files up to 50 MB, and while the Dropbox desktop client lets you add really large files, the web interface has a 300 MB limit, so if you were on another PC and wanted to add giant files to your Dropbox, you’d need to split them. This same technique also works for any file sharing service—even if you were sending files through email. There’s two ways that you can get around the limits—first, by just compressing the files if you’re close to the limit, but the second and more interesting way is to split up the files into smaller chunks. Keep reading for how to do both. Latest Features How-To Geek ETC The How-To Geek Guide to Learning Photoshop, Part 8: Filters Get the Complete Android Guide eBook for Only 99 Cents [Update: Expired] Improve Digital Photography by Calibrating Your Monitor The How-To Geek Guide to Learning Photoshop, Part 7: Design and Typography How to Choose What to Back Up on Your Linux Home Server How To Harmonize Your Dual-Boot Setup for Windows and Ubuntu Hang in There Scrat! – Ice Age Wallpaper How Do You Know When You’ve Passed Geek and Headed to Nerd? On The Tip – A Lamborghini Theme for Chrome and Iron What if Wile E. Coyote and the Road Runner were Human? [Video] Peaceful Winter Cabin Wallpaper Store Tabs for Later Viewing in Opera with Tab Vault

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  • Coding in large chunks ... Code verification skills

    - by Andrew
    As a follow up to my prev question: What is the best aproach for coding in a slow compilation environment To recap: I am stuck with a large software system with which a TDD ideology of "test often" does not work. And to make it even worse the features like pre-compiled headers/multi-threaded compilation/incremental linking, etc is not available to me - hence I think that the best way out would be to add the extensive logging into the system and to start "coding in large chunks", which I understand as code for a two-three hours first (as opposed to 15-20 mins in TDD) - thoroughly eyeball the code for a 15 minutes and only after all that do the compilation and run the tests. As I have been doing TDD for a quite a while, my code eyeballing / code verification skills got rusty (you don't really need this that much if you can quickly verify what you've done in 5 seconds by running a test or two) - so I am after a recommendations on how to learn these source code verification/error spotting skills again. I know I was able to do that easily some 5-10 years ago when I din't have much support from the compiler/unit testing tools I had until recently, thus there should be a way to get back to the basics.

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  • Sort algorithms that work on large amount of data

    - by Giorgio
    I am looking for sorting algorithms that can work on a large amount of data, i.e. that can work even when the whole data set cannot be held in main memory at once. The only candidate that I have found up to now is merge sort: you can implement the algorithm in such a way that it scans your data set at each merge without holding all the data in main memory at once. The variation of merge sort I have in mind is described in this article in section Use with tape drives. I think this is a good solution (with complexity O(n x log(n)) but I am curious to know if there are other (possibly faster) sorting algorithms that can work on large data sets that do not fit in main memory. EDIT Here are some more details, as required by the answers: The data needs to be sorted periodically, e.g. once in a month. I do not need to insert a few records and have the data sorted incrementally. My example text file is about 1 GB UTF-8 text, but I wanted to solve the problem in general, even if the file were, say, 20 GB. It is not in a database and, due to other constraints, it cannot be. The data is dumped by others as a text file, I have my own code to read this text file. The format of the data is a text file: new line characters are record separators. One possible improvement I had in mind was to split the file into files that are small enough to be sorted in memory, and finally merge all these files using the algorithm I have described above.

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  • Organization standards for large programs

    - by Chronicide
    I'm the only software developer at the company where I work. I was hired straight out of college, and I've been working here for several years. When I started, eveeryone was managing their own data as they saw fit (lots of filing cabinets). Until recently, I've only been tasked with small standalone projects to help with simple workflows. In the beginning of the year I was asked to make a replacement for their HR software. I used SQL Server, Entity Framework, WPF, along with MVVM and Repository/Unit of work patterns. It was a huge hit. I was very happy with how it went, and it was a very solid program. As such, my employer asked me to expand this program into a corporate dashboard that tracks all of their various corporate data domains (People, Salary, Vehicles/Assets, Statistics, etc.) I use integrated authentication, and due to the initial HR build, I can map users to people in positions, so I know who is who when they open the program, and I can show each person a customized dashboard given their work functions. My concern is that I've never worked on such a large project. I'm planning, meeting with end users, developing, documenting, testing and deploying it on my own. I'm part way through the second addition, and I'm seeing that my code is getting disorganized. It's still programmed well, I'm just struggling with the organization of namespaces, classes and the database model. Are there any good guidelines to follow that will help me keep everything straight? As I have it now, I have folders for Data, Repositories/Unit of Work, Views, View Models, XAML Resources and Miscellaneous Utilities. Should I make parent folders for each data domain? Should I make separate EF models per domain instead of the one I have for the entire database? Are there any standards out there for organizing large programs that span multiple data domains? I would appreciate any suggestions.

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  • Storing large array of tiles, but allowing easy access to data

    - by Cyral
    I've been thinking about this for a while. I have a 2D tile bases platformer in XNA with a large array of tile data, I've been running into memory problems with large maps. (I will add chunks soon!) Currently, Each tile contains an Item along with other properties like how its rotated, if it has forground / background, etc. An Item is static and has properties like the name, tooltip, type of item, how much light it emits, the collision it does to player, etc. Examples: public class Item { public static List<Item> Items; public Collision blockCollisionType; public string nameOfItem; public bool someOtherVariable,etc,etc public static Item Air public static Item Stone; public static Item Dirt; static Item() { Items = new List<Item>() { (Stone = new Item() { nameOfItem = "Stone", blockCollisionType = Collision.Solid, }), (Air = new Item() { nameOfItem = "Air", blockCollisionType = Collision.Passable, }), }; } } Would be an Item, The array of Tiles would contain a Tile for each point, public class Tile { public Item item; //What type it is public bool onBackground; public int someOtherVariables,etc,etc } Now, Most would probably use an enum, or a form of ID to identify blocks. Well my system is really nice just to find out about an item. I can simply do tiles[x,y].item.Name To get the name for example. I realized my Item property of the tile is over 1000 Bytes! Wow! What I'm looking for is a way to use an ID (Int or byte depending on how many items) instead of an Item but still have a method for retreiving data about the type of item a tile contains.

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  • Avoid an "out of memory error" in Java(eclipse), when using large data structure?

    - by gnomed
    OK, so I am writing a program that unfortunately needs to use a huge data structure to complete its work, but it is failing with a "out of memory error" during its initialization. While I understand entirely what that means and why it is a problem, I am having trouble overcoming it, since my program needs to use this large structure and I don't know any other way to store it. The program first indexes a large corpus of text files that I provide. This works fine. Then it uses this index to initialize a large 2D array. This array will have nXn entries, where "n" is the number of unique words in the corpus of text. For the relatively small chunk I am testing it on(about 60 files) it needs to make approximately 30,000x30,000 entries. this will probably be bigger once I run it on my full intended corpus too. It consistently fails every time, after it indexes, while it is initializing the data structure(to be worked on later). Things I have done include: revamp my code to use a primitive "int[]" instead of a "TreeMap" eliminate redundant structures, etc... Also, I have run eclipse with "eclipse -vmargs -Xmx2g" to max out my allocated memory I am fairly confident this is not going to be a simple line of code solution, but is most likely going to require a very new approach. I am looking for what that approach is, any ideas? Thanks, B.

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  • Is it possible to connect iPhones through NAT traversal techniques over 3G for peer 2 peer gaming

    - by Dougnukem
    Is it possible to connect an iPhone to another iPhone or any other network client talking that game's protocol. I was thinking that I could use the same NAT Traversal technique used in the XBox 360 to host games on users XBox's through Firewalls. For NAT traversal to work effectively I'd have to have a central server that would allow clients to "broadcast" that they were hosting so that another client could initiate the NAT connection. In the link provided this is called relaying. Is there any inherent limitation of the US AT&T 3G network that will block the NAT traversal techniques (would you be limited to wifi firewall NAT traversal)? NAT Traversal Projects: - PJSIP - providing NAT traversal functionalities by using standard based protocols such as STUN, TURN, and ICE. - Freecast using Apache MINA Java network library for NAT Traversal

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  • Why from a virtualized Ubuntu system I can't discover the ip address of my router?

    - by AndreaNobili
    I am not into computer network and I have the following problem finding my router IP address. I have a Windows 8 PC on on which it is installed VmWare Workstation that virtualizes Linux Ubuntu. The network adapter settings of this Virtual Machine is setted as NAT. Now my problem is that if in the Windows 8 DOS shell I perform the ifconfig statment I obtain C:\Users\Andrea>ipconfig Configurazione IP di Windows Scheda Ethernet tap0: Stato supporto. . . . . . . . . . . . : Supporto disconnesso Suffisso DNS specifico per connessione: techub.lan Scheda Ethernet Connessione di rete Bluetooth: Stato supporto. . . . . . . . . . . . : Supporto disconnesso Suffisso DNS specifico per connessione: Scheda LAN wireless Connessione alla rete locale (LAN)* 11: Stato supporto. . . . . . . . . . . . : Supporto disconnesso Suffisso DNS specifico per connessione: Scheda LAN wireless Wi-Fi: Suffisso DNS specifico per connessione: DSL2750B Indirizzo IPv6 locale rispetto al collegamento . : fe80::89ff:6d12:49cf:4354%13 Indirizzo IPv4. . . . . . . . . . . . : 192.168.1.3 Subnet mask . . . . . . . . . . . . . : 255.255.255.0 Gateway predefinito . . . . . . . . . : 192.168.1.1 Scheda Ethernet Ethernet: Stato supporto. . . . . . . . . . . . : Supporto disconnesso Suffisso DNS specifico per connessione: Scheda Ethernet VMware Network Adapter VMnet1: Suffisso DNS specifico per connessione: Indirizzo IPv6 locale rispetto al collegamento . : fe80::edb3:8352:f954:2b0c%23 Indirizzo IPv4. . . . . . . . . . . . : 192.168.129.1 Subnet mask . . . . . . . . . . . . . : 255.255.255.0 Gateway predefinito . . . . . . . . . : Scheda Ethernet VMware Network Adapter VMnet8: Suffisso DNS specifico per connessione: Indirizzo IPv6 locale rispetto al collegamento . : fe80::d00b:8c6e:98b:f1ec%24 Indirizzo IPv4. . . . . . . . . . . . : 192.168.15.1 Subnet mask . . . . . . . . . . . . . : 255.255.255.0 Gateway predefinito . . . . . . . . . : Scheda Tunnel Teredo Tunneling Pseudo-Interface: Stato supporto. . . . . . . . . . . . : Supporto disconnesso Suffisso DNS specifico per connessione: Scheda Tunnel isatap.techub.lan: Stato supporto. . . . . . . . . . . . : Supporto disconnesso Suffisso DNS specifico per connessione: techub.lan Scheda Tunnel isatap.{5B95051D-79AB-4147-92CF-3A2E16698432}: Stato supporto. . . . . . . . . . . . : Supporto disconnesso Suffisso DNS specifico per connessione: Scheda Tunnel isatap.{340A5FAD-1597-402E-B658-29C37E8F7BC2}: Stato supporto. . . . . . . . . . . . : Supporto disconnesso Suffisso DNS specifico per connessione: Scheda Tunnel isatap.DSL2750B: Suffisso DNS specifico per connessione: DSL2750B Indirizzo IPv6 locale rispetto al collegamento . : fe80::5efe:192.168.1.3%26 Gateway predefinito . . . . . . . . . : So, looking at the previous output it appear clear that the default gateway (my router) is: 192.168.1.1, infact if I open it into a browser it apear to me the login mask to enter in the router settings.... Ok, if now I open the virtualized Ubuntu shell and perform the route command I obtain this output: andrea@andrea-virtual-machine:~$ route Tabella di routing IP del kernel Destination Gateway Genmask Flags Metric Ref Use Iface default 192.168.15.2 0.0.0.0 UG 0 0 0 eth0 link-local * 255.255.0.0 U 1000 0 0 eth0 192.168.15.0 * 255.255.255.0 U 1 0 0 eth0 So, here it say to me that the default gateway is 192.168.15.2 (that is not my router ip address), why? My idea is that it could depend by the NAT. Because my Windows system is connected using the wireless but in the virtualized Ubuntu I see that I am connected to a "wired network". So I think that the NAT virtualize a network adapter (or something like this) and that 192.168.15.2 could be the ip address of this network adapter... But it seems strange to me because, as you can see in the previous ipconfig output the VmWare network adapter addresses are: 192.168.129.1 and 192.168.15.1. So I have also 2 others doubts: 1) What device represents the 192.168.15.2 ip address that the virtualized Ubuntu see as Default gateway but that is not my router? 2) What exactly do the two VmWare network adapter that I have configured into my Windows 8 system? There is a way to discover my router ip from the virtualized Ubuntu system ? Tnx Andrea

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  • What should i do for accomodating large scale data storage and retrieval?

    - by kailashbuki
    There's two columns in the table inside mysql database. First column contains the fingerprint while the second one contains the list of documents which have that fingerprint. It's much like an inverted index built by search engines. An instance of a record inside the table is shown below; 34 "doc1, doc2, doc45" The number of fingerprints is very large(can range up to trillions). There are basically following operations in the database: inserting/updating the record & retrieving the record accoring to the match in fingerprint. The table definition python snippet is: self.cursor.execute("CREATE TABLE IF NOT EXISTS `fingerprint` (fp BIGINT, documents TEXT)") And the snippet for insert/update operation is: if self.cursor.execute("UPDATE `fingerprint` SET documents=CONCAT(documents,%s) WHERE fp=%s",(","+newDocId, thisFP))== 0L: self.cursor.execute("INSERT INTO `fingerprint` VALUES (%s, %s)", (thisFP,newDocId)) The only bottleneck i have observed so far is the query time in mysql. My whole application is web based. So time is a critical factor. I have also thought of using cassandra but have less knowledge of it. Please suggest me a better way to tackle this problem.

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  • iptables (NAT/PAT) setup for SSH & Samba

    - by IanVaughan
    I need to access a Linux box via SSH & Samba that is hidden/connected behind another one. Setup :- A switch B C |----| |---| |----| |----| |eth0|----| |----|eth0| | | |----| |---| |eth1|----|eth1| |----| |----| Eg, SSH/Samba from A to C How does one go about this? I was thinking that it cannot be done via IP alone? Or can it? Could B say "hi on eth0, if your looking for 192.168.0.2, its here on eth1"? Is this NAT? This is a large private network, so what about if another PC has that IP?! More likely it would be PAT? A would say "hi 192.168.109.15:1234" B would say "hi on eth0, traffic for port 1234 goes on here eth1" How could that be done? And would the SSH/Samba demons see the correct packet header info and work?? IP info :- A - eth0 - 192.168.109.2 B - eth0 - B1 = 192.168.109.15 B2 = 172.24.40.130 - eth1 - 192.168.0.1 C - eth1 - 192.168.0.2 A, B & C are RHEL (RedHat) But Windows computers can be connected to the switch. I configured the 192.168.0.* IPs, they are changeable. Update after response from Eddie Few problems (and Machines' B IP is different!) From A :- ssh 172.24.40.130 works ok, (can get to B2) but ssh 172.24.40.130 -p 2022 -vv times out with :- OpenSSH_4.3p2, OpenSSL 0.9.8e-fips-rhel5 01 Jul 2008 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to 172.24.40.130 [172.24.40.130] port 2022. ...wait ages... debug1: connect to address 172.24.40.130 port 2022: Connection timed out ssh: connect to host 172.24.40.130 port 2022: Connection timed out From B2 :- $ service iptables status Table: filter Chain INPUT (policy ACCEPT) num target prot opt source destination Chain FORWARD (policy ACCEPT) num target prot opt source destination 1 ACCEPT tcp -- 0.0.0.0/0 192.168.0.2 tcp dpt:22 Chain OUTPUT (policy ACCEPT) num target prot opt source destination Table: nat Chain PREROUTING (policy ACCEPT) num target prot opt source destination 1 DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:2022 to:192.168.0.2:22 Chain POSTROUTING (policy ACCEPT) num target prot opt source destination Chain OUTPUT (policy ACCEPT) num target prot opt source destination And ssh from B2 to C works fine :- $ ssh 192.168.0.2 Route info :- $ route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.0.0 * 255.255.255.0 U 0 0 0 eth1 172.24.40.0 * 255.255.255.0 U 0 0 0 eth0 169.254.0.0 * 255.255.0.0 U 0 0 0 eth1 default 172.24.40.1 0.0.0.0 UG 0 0 0 eth0 $ ip route 192.168.0.0/24 dev eth1 proto kernel scope link src 192.168.0.1 172.24.40.0/24 dev eth0 proto kernel scope link src 172.24.40.130 169.254.0.0/16 dev eth1 scope link default via 172.24.40.1 dev eth0 So I just dont know why the port forward doesnt work from A to B2?

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  • Virtual Network Interface and NAT disables localhost access for MySQL and Apache

    - by Interarticle
    I'm running an Ubuntu Server 12.04, and recently I configured it to do NAT for my laptop. Since the server has only one NIC, I followed instructions online to create a virtual network device (eth0:0) that has a LAN IP address, then further configured iptables and UFW to allow internet sharing. However, just a few days ago, I discovered that one of the PHP pages hosted on the server failed for no apparent reason. A little digging revealed that the MySQL server started refusing connections from localhost. The same happened with a page (PhpMyAdmin) that was configured to be accessible only from localhost (in Apache2). The error, as shown by $mysql --protocol=tcp -u root -p looks like ERROR 1130 (HY000): Host '<host name of eth0>' is not allowed to connect to this MySQL server However, the funny thing is, I configured the mysql server to allow root access from localhost (only). Moreover, the mysql server listens only on 127.0.0.1:3306, as shown by: sudo netstat -npa | head Active Internet connections (servers and established) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 127.0.0.1:3306 0.0.0.0:* LISTEN 1029/mysqld which means that the connection could have only come from 127.0.0.1 (Note that MySQL is working because I can still connect to it via unix domain sockets) In effect, it seems that all tcp connections originating from 127.0.0.1 to 127.0.0.1 appear to any local daemon to come from the eth0 IP address. Indeed, apache2 allowed me to access PhpMyAdmin after I added allow <eth0 IP address>. The following are my network configurations (redacted): /etc/hosts: 127.0.0.1 localhost 211.x.x.x <host name of eth0> <server name> #IPv6 Defaults follows .... /etc/network/interfaces: auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 211.x.x.x netmask 255.255.255.0 gateway 211.x.x.x dns-nameservers 8.8.8.8 # dns-* options are implemented by the resolvconf package, if installed dns-search xxxxxxx.com hwaddress ether xx:xx:xx:xx:xx:xx auto eth0:0 iface eth0:0 inet static address 192.168.57.254 netmask 255.255.254.0 broadcast 192.168.57.255 network 192.168.57.0 /etc/ufw/sysctl.conf: #Uncommented the following lines net/ipv4/ip_forward=1 net/ipv6/conf/default/forwarding=1 /etc/default/ufw: DEFAULT_FORWARD_POLICY="ACCEPT" #Changed DROP to ACCEPT /etc/init/internet-sharing.conf (upstart script I wrote), section pre-start script: iptables -A FORWARD -o eth0 -i eth0:0 -s 192.168.57.22 -m conntrack --ctstate NEW -j ACCEPT iptables -A FORWARD -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT iptables -A POSTROUTING -t nat -j MASQUERADE Note again that my problem here is that programs cannot access localhost tcp services, from the server itself, and that access is blocked because the services have access control allowing only 127.0.0.1. I have no problem connecting (as in TCP connections) to services via tcp, even if the services listen only on 127.0.0.1. I do NOT want to connect to the services from another computer.

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  • Google I/O 2011: JavaScript Programming in the Large with Closure Tools

    Google I/O 2011: JavaScript Programming in the Large with Closure Tools Michael Bolin Most developers who have tinkered with JavaScript could not imagine writing 1000 lines of code in such a language, let alone 100000. Yet that is exactly what Google engineers have done using a suite of JavaScript tools named "Closure" to produce many of the most popular and sophisticated applications on the Web, such as Gmail and Google Maps. From: GoogleDevelopers Views: 4915 35 ratings Time: 57:07 More in Science & Technology

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  • Implementing the Security Development Lifecycle (SDL) at a Large Insurance Company

    Find out how Cigital, an SDL Pro Network member, assisted a large insurance company adopt the Microsoft SDL. The case study describes both the business drivers leading up to the company's recognizing the need for incorporating the SDL within their development process as well as the initial roll out of the SDL....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Selecting which IP address to use for outgoing requests from behind a NAT

    - by iamrohitbanga
    Our organization has several external IP addresses. I am behind 2 layers of NAT and the servers choose which IP address to route my traffic to. Can I specify which IP address to use when finally leaving the organizations network. I know that source routing can be done in IPv4 by adding some options in the header. But can I configure my PC to add these options automatically. I have both a Windows and a Linux Machine.

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  • Advice on designing a robust program to handle a large library of meta-information & programs

    - by Sam Bryant
    So this might be overly vague, but here it is anyway I'm not really looking for a specific answer, but rather general design principles or direction towards resources that deal with problems like this. It's one of my first large-scale applications, and I would like to do it right. Brief Explanation My basic problem is that I have to write an application that handles a large library of meta-data, can easily modify the meta-data on-the-fly, is robust with respect to crashing, and is very efficient. (Sorta like the design parameters of iTunes, although sometimes iTunes performs more poorly than I would like). If you don't want to read the details, you can skip the rest Long Explanation Specifically I am writing a program that creates a library of image files and meta-data about these files. There is a list of tags that may or may not apply to each image. The program needs to be able to add new images, new tags, assign tags to images, and detect duplicate images, all while operating. The program contains an image Viewer which has tagging operations. The idea is that if a given image A is viewed while the library has tags T1, T2, and T3, then that image will have boolean flags for each of those tags (depending on whether the user tagged that image while it was open in the Viewer). However, prior to being viewed in the Viewer, image A would have no value for tags T1, T2, and T3. Instead it would have a "dirty" flag indicating that it is unknown whether or not A has these tags or not. The program can introduce new tags at any time (which would automatically set all images to "dirty" with respect to this new tag) This program must be fast. It must be easily able to pull up a list of images with or without a certain tag as well as images which are "dirty" with respect to a tag. It has to be crash-safe, in that if it suddenly crashes, all of the tagging information done in that session is not lost (though perhaps it's okay to loose some of it) Finally, it has to work with a lot of images (10,000) I am a fairly experienced programmer, but I have never tried to write a program with such demanding needs and I have never worked with databases. With respect to the meta-data storage, there seem to be a few design choices: Choice 1: Invidual meta-data vs centralized meta-data Individual Meta-Data: have a separate meta-data file for each image. This way, as soon as you change the meta-data for an image, it can be written to the hard disk, without having to rewrite the information for all of the other images. Centralized Meta-Data: Have a single file to hold the meta-data for every file. This would probably require meta-data writes in intervals as opposed to after every change. The benefit here is that you could keep a centralized list of all images with a given tag, ect, making the task of pulling up all images with a given tag very efficient

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  • Developing an analytics's system processing large amounts of data - where to start

    - by Ryan
    Imagine you're writing some sort of Web Analytics system - you're recording raw page hits along with some extra things like tagging cookies etc and then producing stats such as Which pages got most traffic over a time period Which referers sent most traffic Goals completed (goal being a view of a particular page) And more advanced things like which referers sent the most number of vistors who later hit a goal. The naieve way of approaching this would be to throw it in a relational database and run queries over it - but that won't scale. You could pre-calculate everything (have a queue of incoming 'hits' and use to update report tables) - but what if you later change a goal - how could you efficiently re-calculate just the data that would be effected. Obviously this has been done before ;) so any tips on where to start, methods & examples, architecture, technologies etc.

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  • Large resolution differences

    - by Robin Betka
    I want to develop a game on multiple devices such as PC, Android or IOS. Want it to be in 1080p, but that means a massive scale down for the smartphones. I know how to do that, just render everything on a 1080p rendertarget and then render it on the screen smaller. But what should I do so that the scalling down doesn't look bad and blury? I can't do it vector based or anything because the sprites simply need a specific size. Should I make the sprites power of two size to get some nice mipmapping? And which other settings can I do? Or should I rather go with a lower resolution but then having a little bit worse look PC version? The performance seems not to be a problem for me, so would be sad not using 1080p because of other problems.

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  • Vector.Unproject - Checking if a model intersects a large sprite

    - by Fibericon
    Let's say I have a sprite, drawn like this: spriteBatch.Draw(levelCannons[i].texture, levelCannons[i].position, null, alpha, levelCannons[i].rotation, Vector2.Zero, scale, SpriteEffects.None, 0); Picture levelCannon as being a laser beam that goes across the entire screen. I need to see if my 3d model intersects with the screen space inhabited by the sprite. I managed to dig up Vector.Unproject, but that seems to only be useful when dealing with a single point in 2d space, rather than an area. What can I do in my case?

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