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  • Immediate Propagation in Active Directory

    - by squillman
    It's been a while since I've done any large-scale AD administration so I'm reaching back a bit here. I remember that there are certain security related attributes on a user account object that, due to their nature, are flagged for immediate propagation to other sites. I have a case where passwords resets are not being propagated until scheduled replication happens. I had thought that was a case of immediate propagation. Am I just remembering incorrectly? Domain function level is 2003.

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  • Software development project inception phase

    - by john ryan
    Currently our team develops Web Applications and now we are going to Windows Forms applications. I have created the inception phase for our Windows Forms project structure. eg: ApplicationSolution --> Security Project(Login Authentication) a. Users will be registered with different applications in our application database. eg: ProjectApplicationId|ProjectName | UserId 1 |ProjectApplication1| user 2 |ProjectApplication2| user b. Execute Application (Start) c. On Security dialog, application automatically get the userid of the user and see all the application it is registered using System.Security.Principal.WindowsIdentity.GetCurrent() eg: Prototype Welcome User! Please Choose Appliations you are registered on below: ProjectApplication1 <--this will be a dropdown ProjectApplication2 Password: [*********************] [Access Application Button] d. User selects the application with its password e. If the password is incorrect (application.exit()) else execute Selected Application eg: ProjectApplication1 is selected then execute ProjectApplication1 --> ProjectApplication1 --> ProjectApplication2 --> Many to come ++ if ProjectApplications has been closed then restart security Application. My questions on this use case: Is my use case possible? Can you give me any recommendations ? Currently we use setup and deployment to create installer in each Windows Forms application.

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  • Oracle@info360: Advance Beyond Point Solutions To An Enterprise Content Strategy

    - by kellsey.ruppel(at)oracle.com
    The info360/AIIM conference is March 22-24 in Washington DC. We have a number of customer speakers this year talking on the theme of “Advance Beyond Point Solutions To An Enterprise Content Strategy.” These customers all started by addressing a particular use case, but then used the infrastructure they had created to quickly and cost effectively stand up solutions to new business problems.  Andy MacMillan, VP of Product Management at Oracle, will give a thought provoking opening keynote at 8:50 AM on Tuesday, March 22nd. He will be joined by Juan Jose Goldschtein, the CIO of the Organization of American States. The OAS has developed a human rights website that is the front end to a case management system for human rights violations. The implementation supports digital signatures on iPads, so their executives can approve workflows and keep cases moving forward while they are busy traveling and investigating abuses.Other customer speakers include:Tom Robinette, Director of Applications and IT Engineering, Dresser-RandRobin Crisp, Program Manager, FDAMonica Crocker, Corporate Records Manager, Land O’ LakesBrian Skapura, The American Institute of ArchitectsKathy Adams and Leslie Becker, The Nature ConservancyIrfan Motiwala, Sr. VP, Moody’s Investment ServicesMolly Wenzler, Director of Electronic Media, MeadWestvaco Other sessions include our Super Session that kicks off the Oracle Track @info360 on Wednesday. At 11:00 AM, Senior Director of Product Marketing, Howard Beader will present The Social Enterprise – Combining People, Processes and Content. This session will focus on how customers have brought social media, business process management, and content management together to supercharge their organizations. Oracle customers can arrange one-on-one meetings with Oracle executives and product experts, and attend the VIP customer appreciation event. Oracle will be joined by Oracle partners:FujitsuKesteTeamInformaticsKapowSena SystemsDTIYou can learn more about discounts for Oracle customers and register on our Oracle@info360 page.To see more about the customers and sessions that will be presented, you can look at the Oracle Track page on the AIIM/info360 website.Technorati Tags: oracle, AIIM, info360, content management, social enterprise

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  • Two BULK INSERT issues I worked around recently

    - by AaronBertrand
    Since I am still afraid of SSIS, and because I am dealing mostly with CSV files and table structures that are relatively simple and require only one of the three letters in the acronym "ETL," I find myself using BULK INSERT a lot. I have been meaning to switch to using CLR, since I am doing a lot of file system querying using xp_cmdshell, but I haven't had the chance to really explore it yet. I know, a lot of you are probably thinking, wow, look at all those bad habits. But for every person thinking...(read more)

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  • HTML5 data-* (custom data attribute)

    - by Renso
    Goal: Store custom data with the data attribute on any DOM element and retrieve it. Previously under HTML4 we used to use classes to store custom data, something to the affect of <input class="account void limit-5000 over-4999" /> and then have to parse the data out of the class In a book published by Peter-Paul Koch in 2007, ppk on JavaScript, he explains why and how to use custom attributes to make data more accessible to JavaScript, using name-value pairs. Accessing a custom attribute account-limit=5000 is much easier and more intuitive than trying to parse it out of a class, Plus, what if the class name for example "color-5" has a representative class definition in a CSS stylesheet that hides it away or worse some JavaScript plugin that automatically adds 5000 to it, or something crazy like that, just because it is a valid class name. As you can see there are quite a few reasons why using classes is a bad design and why it was important to define custom data attributes in HTML5. Syntax: You define the data attribute by simply prefixing any data item you want to store with any HTML element with "data-". For example to store our customers account data with a hidden input element: <input type="hidden" data-account="void" data-limit=5000 data-over=4999  /> How to access the data: account  -     element.dataset.account limit    -     element.dataset.limit You can also access it by using the more traditional get/setAttribute method or if using jQuery $('#element').attr('data-account','void') Browser support: All except for IE. There is an IE hack around this at http://gist.github.com/362081. Special Note: Be AWARE, do not use upper-case when defining your data elements as it is all converted to lower-case when reading it, so: data-myAccount="A1234" will not be found when you read it with: element.dataset.myAccount Use only lowercase when reading so this will work: element.dataset.myaccount

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  • Benchmarking ORM associations

    - by barerd
    I am trying to benchmark two cases of self referential many to many as described in datamapper associations. Both cases consist of an Item clss, which may require many other items. In both cases, I required the ruby benchmark library and source file, created two items and benchmarked require/unrequie functions as below: Benchmark.bmbm do |x| x.report("require:") { item_1.require_item item_2, 10 } x.report("unrequire:") { item_1.unrequire_item item_2 } end To be clear, both functions are datamapper add/modify functions like: componentMaps.create :component_id => item.id, :quantity => quantity componentMaps.all(:component_id => item.id).destroy! and links_to_components.create :component_id => item.id, :quantity => quantity links_to_components.all(:component_id => item.id).destroy! The results are variable and in the range of 0.018001 to 0.022001 for require function in both cases, and 0.006 to 0.01 for unrequire function in both cases. This made me suspicious about the correctness of my test method. Edit I went ahead and compared a "get by primary key case" to a "finding first matching record case" by: (1..10000).each do |i| Item.create :name => "item_#{i}" end Benchmark.bmbm do |x| x.report("Get") { item = Item.get 9712 } x.report("First") { item = Item.first :name => "item_9712" } end where the results were very different like 0 sec compared to 0.0312, as expected. This suggests that the benchmarking works. I wonder whether I benchmarked the two types of associations correctly, and whether a difference between 0.018 and 0.022 sec significant?

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  • We're Subversion Geeks and we want to know the benefits of Mercurial

    - by Matt
    Having read I'm a Subversion geek, why should I consider or not consider Mercurial or Git or any other DVCS. I have a related follow up question. I read that question and read the recommended links and videos and I see the benefits but I don't see the overall mindshift people are talking about. Our team is of 8-10 developers that work on one large code base consisting of 60 projects. We use Subversion and have a main trunk. When a developer starts a new Fogbugz case they create a svn branch, do the work on the branch and when they're done they merge back to the trunk. Occasionally they may stay on the branch for an extended time and merge the trunk to the branch to pick up the changes. When I watched Linus talk about people creating a branch and never doing it again, that's not us at all. We create probably 50-100 branches a week without issue. The biggest challenge is the merging but we've gotten pretty good at that as well. I tend to merge by fogbugz case & checkin rather than the entire root of the branch. We never work remotely and we never make branches off of branches. If you're the only one working in that section of the code base then the merge to the trunk goes smoothly. If someone else had modified the same section of code then the merge can get messy and you might need to do some surgery. Conflicts are conflicts, I don't see how any system could get it right most of the time unless if was smart enough to understand the code. After creating a branch the following checkout of 60k+ files takes some time but that would be an issue with any source control system we'd use. Is there some benefit of any DVCS that we're not seeing that would be of great help to us?

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  • How do you track third-party software licenses?

    - by emddudley
    How do you track licenses for third-party libraries that you use in your software? How did you vet the licenses? Sometimes licenses change or libraries switch licenses--how do you stay up to date? At the moment I've got an Excel spreadsheet with worksheets for third-party software, licenses, and the projects we use them on (organized like a relational database). It seems to work OK, but I think it will go out-of-date pretty quickly.

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  • Ubuntu Server and setting up two nic cards

    - by kmalik
    I have ubuntu server on a computer with a wireless and hardwired nic card. The wireless needs to get the internet and pass it to the ubuntu server as well as pass it along to the hardwired nic card to more computers. I am having issues getting the basic set up as I believe the route table is grabbing from the wrong nic card. The router is 192.168.1.0 and the server is set to 192.168.1.11 on the wireless card through DHCP ETH0 (wired nic card) is set up to be 10.10.10.0 and the server is 10.10.10.1) I am not a linux or networking guru but basically I am trying to have internet come from a guest network 192.168.1.0 i believe to give internet to the ubuntu server then the ubuntu server will also A) have the wired nic serve DHCP addresses to other computers via a switch or router (that acts as a switch) via 10.10.10.0 addresses. And I would love if it also passed along internet capabilities as well if possible. Bu really at this point my hope is to at least get the internet working on the server and the DHCP to pass correctly. At the moment the specific issue I am having is getting ubuntu server to connect to the internet and have both nic cards up and running correctly. Any help would be appreciated! The route table is as follows: Destination Gateway GM Flags Metric Iface 0.0.0.0 10.10.10.1 0.0.0.0 UG 100 eth0 10.10.10.0 0.0.0.0 255.255.255.0 U 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 0 eth0 1992.168.1.0 0.0.0.0 255.255.255.255.0 U 0 eth1 My interfaces is set up as follows: auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 10.10.10.1 netmask 255.255.255.0 network 10.10.10.0 broadcast 10.10.10.255 gateway 10.10.10.1 domain-name-servers 192.168.1.0 auto eth1 iface eth1 inet dhcp netmask 255.255.255.0 gateway 192.168.1.0 wpa-driver wext wpa-ssid "ssid_name" wpa-ap-scan 1 wpa-proto wpa wpa-pairwise ccmp wpa-group ccmp wpa-key-mgmt wpa-psk wpa-psk "HASH" My DHCPD.conf (as there is a domain name server on here is as follows): ddns-update-style none default-lease-time 600 max-lease-time 7200 authoritative option domain-name "Kamron's Network" option subnet-mask 255.255.255.0 option broadcast-address 10.10.10.255 option routers 192.168.1.0 option domain-name-server 192.168.1.0 98.223.128.213 ooption subnet 10.10.10.0 netmask 255.255.255.0 { range 10.10.10.10 10.10.10.99 } log-facility local7

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  • Acceptable placement of the composition root using dependency injection and inversion of control containers

    - by Lumirris
    I've read in several sources including Mark Seemann's 'Ploeh' blog about how the appropriate placement of the composition root of an IoC container is as close as possible to the entry point of an application. In the .NET world, these applications seem to be commonly thought of as Web projects, WPF projects, console applications, things with a typical UI (read: not library projects). Is it really going against this sage advice to place the composition root at the entry point of a library project, when it represents the logical entry point of a group of library projects, and the client of a project group such as this is someone else's work, whose author can't or won't add the composition root to their project (a UI project or yet another library project, even)? I'm familiar with Ninject as an IoC container implementation, but I imagine many others work the same way in that they can scan for a module containing all the necessary binding configurations. This means I could put a binding module in its own library project to compile with my main library project's output, and if the client wanted to change the configuration (an unlikely scenario in my case), they could drop in a replacement dll to replace the library with the binding module. This seems to avoid the most common clients having to deal with dependency injection and composition roots at all, and would make for the cleanest API for the library project group. Yet this seems to fly in the face of conventional wisdom on the issue. Is it just that most of the advice out there makes the assumption that the developer has some coordination with the development of the UI project(s) as well, rather than my case, in which I'm just developing libraries for others to use?

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  • Multiple monitors showing same screen but different resolutions

    - by Luis Alvarado
    Is it possible to have 2 or more monitors showing the same screen, for example the same desktop but with different resolutions. Like the clone option in Nvidia or the mirror option using the Display settings in Ubuntu but instead of showing the same output with the same resolution, the both show the same output using a resolution that is native for each monitor connected. In my case if I have a netbook that has max resolution of 1360x768 and a TV that has 1280x1024, the would both show the same desktop but each with their own resolution that is compatible for each device. This would help in trying to find a resolution that works on both monitors and in cases like a mini netbook and a huge TV it would solve issues like having max 800x600 in one monitor and min 1024x768 in the other. In the case I tested I was using an HDMI cable but this question also involves VGA and any other connection. I have 3 tests scenarios for this: Scenario 1 - Laptop HP DV6000 (Intel Integrated Video) with 1360x760 connected to a Samsung LED 42 TV that has 1280x900. Scenario 2 - Laptop EEE with 1024x600 (Intel Integrated Video) connected to Sony LCD TV that supports 1280x900. Scenario 3 - Intel Desktop with Nvidia 440 GT with HDMI connected to Soneview 32' TV that supports 1920x1080 and VGA connected to an Epson Video Beam that supports 1280x1024 max. In this 3 scenarios I need to be able to show the same desktop and same views but on different resolutions for each output device. UPDATE: Tested with Xubuntu and the way it handles multiple monitors is precisely what I am asking. The ability to handle the resolution of different monitors showing the same thing.

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  • Ray Tracing concers: Efficient Data Structure and Photon Mapping

    - by Grieverheart
    I'm trying to build a simple ray tracer for specific target scenes. An example of such scene can be seen below. I'm concerned as to what accelerating data structure would be most efficient in this case since all objects are touching but on the other hand, the scene is uniform. The objects in my ray tracer are stored as a collection of triangles, thus I also have access to individual triangles. Also, when trying to find the bounding box of the scene, how should infinite planes be handled? Should one instead use the viewing frustum to calculate the bounding box? A few other questions I have are about photon mapping. I've read the original paper by Jensen and many more material. In the compact data structure for the photon they introduce, they store photon power as 4 chars, which from my understanding is 3 chars for color and 1 for flux. But I don't understand how 1 char is enough to store a flux of the order of 1/n, where n is the number of photons (I'm also a bit confused about flux vs power). The other question about photon mapping is, if it would be more efficient in my case to store photons per object (or even per Object's triangle) instead of using a balanced kd-tree. Also, same question about bounding box of the scene but for photon mapping. How should one find a bounding box from the pov of the light when infinite planes are involved?

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  • Thunderbird is preferred mail app, messaging menu still loads evolution [closed]

    - by user9069
    Possible Duplicate: Is there a way to add Mozilla Thunderbird to the messaging menu? Hi, After installing ubuntu I setup my email in evolution, which is fine but on balance I prefer Thunderbird so I installed and set that up. Under preferred applications I have set the mail to Thunderbird, but when I click on the icon in the top right (the mail envelope) and select mail it still loads evolution. Is there a way to switch this to Thunderbird?

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  • Given a project and working with 1 other person - never worked with someone before

    - by Celeritas
    I'm taking a class where I work with a partner to implement the link layer of the OSI model. I've worked programmed with a partner once before and it went bad. Is the goal to divide the work up and decides who does what or should one person code and the other person reviews and switch roles after a while? Any tips are much appreciated. Literally I know nothing about working with a partner to program so even if it's basic please tell me.

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  • WAIT-VHUB ? Whats Going On ?

    - by Neeraj Gupta
    I know many of you have been working on Oracle's Exalogic and other Engineered Systems. With partitions enabled now, things have gone multi dimension. But its fun. Isn't it ? While you have some EoIB configurations together with InfiniBand partitions, the VNICs are not coming up and staying in WAIT-VHUB state ?  Chances are that you have forgot to add InfiniBand Gateway switches' Bridge-X port GUIDs to your partition. These must be added as FULL members for EoIB to work properly. VHUB means a virtual hub in EoIB. Bridge-x is the access point for hosts to work over EoIB so thats why it must be a full member in partition. Step 1: Find out the port GUIDs of your bridge-x devices in IB Gateway switch. # showgwports INTERNAL PORTS: --------------- Device   Port Portname  PeerPort PortGUID           LID    IBState  GWState --------------------------------------------------------------------------- Bridge-0  1   Bridge-0-1    4    0x0010e00c1b60c001 0x0002 Active   Up Bridge-0  2   Bridge-0-2    3    0x0010e00c1b60c002 0x0006 Active   Up Bridge-1  1   Bridge-1-1    2    0x0010e00c1b60c041 0x0026 Active   Up Bridge-1  2   Bridge-1-2    1    0x0010e00c1b60c042 0x002a Active   Up Step 2: Add these port GUIDs to the IB partition associated with EoIB. Login to master SM switch for this task. # smpartition start # smpartition add -pkey <PKey> -port <port GUID> -m full # smpartition commit Enjoy ! 

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  • Ubuntu 12.04 freeze on Ctrl+ALT+F1

    - by user93800
    I have Radeon card connected over HDMI to my TV. To resolve bug with HDMI-sound, I switch between virtual terminal and GNOME desktop each time the TV is switched on with CTRL+ALT+F1 and after console appear with CTRL+ALT+F7. It's ugly, but its worked for me. Since yesterday I got system freezes on CTRL+ALT+F1 - no reaction on keyboard, mouse pointer disappear at all, GNOME desktop still displayed. Probably has nothing to do with HDMI. Any suggestion how to resolve it?

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  • Windows Firewall allows connection from any IP regardless of rule that only allow a specific IP

    - by Pierre-Alain Vigeant
    I have configured the Windows Firewall to Block (default) incoming connection on the public profile. I have created a rule for a port (in this case, this is Sql Server) that explicitly states that only my office static IP is allowed. If I test from my office, I am able to connect to the port. I was expecting that anybody outside the office would not be able to connect, but this is not the case. I asked a friend to telnet the port to see if it would reply and it does even if he's not on my network. I am a bit confuse here. Shouldn't it block everybody but the given IP? Is my server completely unsecured?

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  • Cannot install Ubuntu on an Acer Aspire One 756

    - by Byron807
    I have used Ubuntu before, in virtual machines, but today I decided to make the leap and I bought a netbook to install Ubuntu as a "real" OS alongside Windows. The netbook I bought is an Acer Aspire One 756, with a 64-bit Intel processor, 4GB RAM, and Windows 8 as the default OS. I have now encountered several obstacles that actually prevent me from installing Ubuntu 12.10. Here are all the things I have tried so far: Used a live CD, in combination with a USB DVD drive. (I should point out that the Aspire One does not have an optical drive.) The computer does not boot in Ubuntu; the drive keeps spinning, but nothing happens, even though I changed the boot order in the BIOS. Used a USB drive created via the tool available on pendrivelinux.com. Again, I've made changes to the BIOS to make sure the computer tries to boot from USB before using the built-in HDD. The results vary in this case: sometimes, the computer keeps rebooting like crazy until I remove the USB drive, at which point the computer boots into Windows 8, as expected. If I use a different USB drive, I get an error message that says that the USB drive has been blocked due to "the current security policy". Tried to install Ubuntu via Wubi. The program appears to install something, but at some point during the installation process, I get a non-specified error message and nothing else happens. I am not sure if these are known issues; in any case, searching the forum has not yielded any results, so I thought I should simply describe my problem here in the hope that this question has not been answered before. I would greatly appreciate any help with this annoying problem. Of course, if anything is unclear, do not hesitate to ask for further details.

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  • Step-by-Step: Implementing Hyper-V Network Virtualization with Windows Server 2012

    - by KeithMayer
    True network and virtual machine portability - that's the ultimate goal of Hyper-V Network Virtualization - allowing you, as an IT Pro, to align changing business needs with the best physical resource locations to run your VMs and network services - easily, without the sweeping network, router, switch, firewall and DNS changes with which we'd traditionally be plagued when merely attempting the feat of relocating VMs to a new rack, subnet or data center ... WOW!

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  • "Siebel2FusionCRM Integration" solution by ec4u (D)

    - by Richard Lefebvre
    ec4u, a CRM System Integration leader based in Germany and Switzerland, and an historical Oracle/Siebel partner, offers a complete "Siebel2FusionCRM Integration" solution, based on tools methodology and services. ec4u Siebel2FusionCRM Integration solution's main objectives are: Integration between Siebel (on-premise) and Fusion CRM / Marketing (“in the cloud”) Accounts, Contacts and Addresses are maintained by Sales in Siebel CRM and synchronized in real-time into Fusion CRM / Marketing CDM Processing ensures clean data for marketing campaigns (validation and deduplication) Create E-Mail marketing campaigns and newsletters in Fusion The solution features: Upsert processes figure out what information needs to be updated, inserted or terminated (deleted). However, as Siebel is the data master, it is still a one-way synchronization. Handle deleted or nullified information by terminating them in Fusion CRM (set start and end date to define the validity period) Initial load and real-time synchronization use the same processes Invocations/Operations can be repeated due to no transactional support from Fusion web services Tagging sub entries in case of 1 to N mapping (Example: Telephone number is one simple field in Siebel but in Fusion you can have multiple telephone numbers in a sub table) E-Mail-Notification in case of any error (containing error message, instance number, detailed payload) Schematron Validation Interested? Looking for more details or a partnership with ec4u for a "Siebel2FusionCRM Integration" project? Contact: Gregor Bublitz, Director Expert Services ([email protected])

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  • Of transactions and Mongo

    - by Nuri Halperin
    Originally posted on: http://geekswithblogs.net/nuri/archive/2014/05/20/of-transactions-and-mongo-again.aspxWhat's the first thing you hear about NoSQL databases? That they lose your data? That there's no transactions? No joins? No hope for "real" applications? Well, you *should* be wondering whether a certain of database is the right one for your job. But if you do so, you should be wondering that about "traditional" databases as well! In the spirit of exploration let's take a look at a common challenge: You are a bank. You have customers with accounts. Customer A wants to pay B. You want to allow that only if A can cover the amount being transferred. Let's looks at the problem without any context of any database engine in mind. What would you do? How would you ensure that the amount transfer is done "properly"? Would you prevent a "transaction" from taking place unless A can cover the amount? There are several options: Prevent any change to A's account while the transfer is taking place. That boils down to locking. Apply the change, and allow A's balance to go below zero. Charge person A some interest on the negative balance. Not friendly, but certainly a choice. Don't do either. Options 1 and 2 are difficult to attain in the NoSQL world. Mongo won't save you headaches here either. Option 3 looks a bit harsh. But here's where this can go: ledger. See, and account doesn't need to be represented by a single row in a table of all accounts with only the current balance on it. More often than not, accounting systems use ledgers. And entries in ledgers - as it turns out – don't actually get updated. Once a ledger entry is written, it is not removed or altered. A transaction is represented by an entry in the ledger stating and amount withdrawn from A's account and an entry in the ledger stating an addition of said amount to B's account. For sake of space-saving, that entry in the ledger can happen using one entry. Think {Timestamp, FromAccountId, ToAccountId, Amount}. The implication of the original question – "how do you enforce non-negative balance rule" then boils down to: Insert entry in ledger Run validation of recent entries Insert reverse entry to roll back transaction if validation failed. What is validation? Sum up the transactions that A's account has (all deposits and debits), and ensure the balance is positive. For sake of efficiency, one can roll up transactions and "close the book" on transactions with a pseudo entry stating balance as of midnight or something. This lets you avoid doing math on the fly on too many transactions. You simply run from the latest "approved balance" marker to date. But that's an optimization, and premature optimizations are the root of (some? most?) evil.. Back to some nagging questions though: "But mongo is only eventually consistent!" Well, yes, kind of. It's not actually true that Mongo has not transactions. It would be more descriptive to say that Mongo's transaction scope is a single document in a single collection. A write to a Mongo document happens completely or not at all. So although it is true that you can't update more than one documents "at the same time" under a "transaction" umbrella as an atomic update, it is NOT true that there' is no isolation. So a competition between two concurrent updates is completely coherent and the writes will be serialized. They will not scribble on the same document at the same time. In our case - in choosing a ledger approach - we're not even trying to "update" a document, we're simply adding a document to a collection. So there goes the "no transaction" issue. Now let's turn our attention to consistency. What you should know about mongo is that at any given moment, only on member of a replica set is writable. This means that the writable instance in a set of replicated instances always has "the truth". There could be a replication lag such that a reader going to one of the replicas still sees "old" state of a collection or document. But in our ledger case, things fall nicely into place: Run your validation against the writable instance. It is guaranteed to have a ledger either with (after) or without (before) the ledger entry got written. No funky states. Again, the ledger writing *adds* a document, so there's no inconsistent document state to be had either way. Next, we might worry about data loss. Here, mongo offers several write-concerns. Write-concern in Mongo is a mode that marshals how uptight you want the db engine to be about actually persisting a document write to disk before it reports to the application that it is "done". The most volatile, is to say you don't care. In that case, mongo would just accept your write command and say back "thanks" with no guarantee of persistence. If the server loses power at the wrong moment, it may have said "ok" but actually no written the data to disk. That's kind of bad. Don't do that with data you care about. It may be good for votes on a pole regarding how cute a furry animal is, but not so good for business. There are several other write-concerns varying from flushing the write to the disk of the writable instance, flushing to disk on several members of the replica set, a majority of the replica set or all of the members of a replica set. The former choice is the quickest, as no network coordination is required besides the main writable instance. The others impose extra network and time cost. Depending on your tolerance for latency and read-lag, you will face a choice of what works for you. It's really important to understand that no data loss occurs once a document is flushed to an instance. The record is on disk at that point. From that point on, backup strategies and disaster recovery are your worry, not loss of power to the writable machine. This scenario is not different from a relational database at that point. Where does this leave us? Oh, yes. Eventual consistency. By now, we ensured that the "source of truth" instance has the correct data, persisted and coherent. But because of lag, the app may have gone to the writable instance, performed the update and then gone to a replica and looked at the ledger there before the transaction replicated. Here are 2 options to deal with this. Similar to write concerns, mongo support read preferences. An app may choose to read only from the writable instance. This is not an awesome choice to make for every ready, because it just burdens the one instance, and doesn't make use of the other read-only servers. But this choice can be made on a query by query basis. So for the app that our person A is using, we can have person A issue the transfer command to B, and then if that same app is going to immediately as "are we there yet?" we'll query that same writable instance. But B and anyone else in the world can just chill and read from the read-only instance. They have no basis to expect that the ledger has just been written to. So as far as they know, the transaction hasn't happened until they see it appear later. We can further relax the demand by creating application UI that reacts to a write command with "thank you, we will post it shortly" instead of "thank you, we just did everything and here's the new balance". This is a very powerful thing. UI design for highly scalable systems can't insist that the all databases be locked just to paint an "all done" on screen. People understand. They were trained by many online businesses already that your placing of an order does not mean that your product is already outside your door waiting (yes, I know, large retailers are working on it... but were' not there yet). The second thing we can do, is add some artificial delay to a transaction's visibility on the ledger. The way that works is simply adding some logic such that the query against the ledger never nets a transaction for customers newer than say 15 minutes and who's validation flag is not set. This buys us time 2 ways: Replication can catch up to all instances by then, and validation rules can run and determine if this transaction should be "negated" with a compensating transaction. In case we do need to "roll back" the transaction, the backend system can place the timestamp of the compensating transaction at the exact same time or 1ms after the original one. Effectively, once A or B visits their ledger, both transactions would be visible and the overall balance "as of now" would reflect no change.  The 2 transactions (attempted/ reverted) would be visible , since we do actually account for the attempt. Hold on a second. There's a hole in the story: what if several transfers from A to some accounts are registered, and 2 independent validators attempt to compute the balance concurrently? Is there a chance that both would conclude non-sufficient-funds even though rolling back transaction 100 would free up enough for transaction 117 (some random later transaction)? Yes. there is that chance. But the integrity of the business rule is not compromised, since the prime rule is don't dispense money you don't have. To minimize or eliminate this scenario, we can also assign a single validation process per origin account. This may seem non-scalable, but it can easily be done as a "sharded" distribution. Say we have 11 validation threads (or processing nodes etc.). We divide the account number space such that each validator is exclusively responsible for a certain range of account numbers. Sounds cunningly similar to Mongo's sharding strategy, doesn't it? Each validator then works in isolation. More capacity needed? Chop the account space into more chunks. So where  are we now with the nagging questions? "No joins": Huh? What are those for? "No transactions": You mean no cross-collection and no cross-document transactions? Granted - but don't always need them either. "No hope for real applications": well... There are more issues and edge cases to slog through, I'm sure. But hopefully this gives you some ideas of how to solve common problems without distributed locking and relational databases. But then again, you can choose relational databases if they suit your problem.

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  • Domain changes required for SSL integration

    - by user131003
    Currently my site supports regular payment options (User is taken to Payment Gateway/PG website). Now I'm trying to implement "seamless" PG integration. I need SSL for this. I'm having a dedicated server with 5 static IPs from Hostgator/HG. options: I take SSL for www.my_domain.com. According to HG, I need to change IP of main site as current IP is not really dedicated as it is being shared by cpanel etc. So They need to bind another dedicated IP to main domain for SSL to work. This would required DNS change for main website and hence cause few hours downtime (which is ok). I've noticed that most of the e-commerce websites are using subdomains like secure.my_domain.com for ssl/https. This sounds like a better approach. But I've got few doubts in this case: a) Would I need to re-register with existing PGs (Paypal, Google Checkout, Authorize.net) if I switch to subdomain? Re-registering is not an option for me. b) Would DNS change be required for www.my_domain.com in this case. This confusion arose because of following reply from HG : "If the sub domain secure.my_domain.com is added to an existing cPanel it will use the IP for that cPanel so as long as it is a Dedicated IP that will be fine. If secure.my_domain.com gets setup as its own cPanel it will need to be assigned to a Dedicated IP which would have a DNS change involved.". Please suggest?

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  • Problem using Skype Screenshare on dual monitors

    - by toobsco42
    I am on Ubuntu 12.04 and when using the screenshare feature of Skype 4.0 on a single monitor I dont have an issue. However as soon as i switch to using dual monitors and try to set up a screenshare, it doesn't work. Does anyone know if this is a known bug in the Skype app? Thanks. Apparently Skype's log files are encrypted, and they recommend just sending the log files to them so that they can determine how to resolve the issue.

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  • OS X Snow Leopard, change file permissions on copy

    - by Francesco K
    I work with OS X, Snow Leopard and need to allow users to make copies of files (templates) located in a read-only repository for subsequent editing. The repository is located on a separate physical drive mounted to the OS X boot volume. As this is a shared computer in a school environment, all users access the machine via a single login ("user_local"). Whether using POSIX permissions or ACLs, the use case requires the file permissions to change from "read" to "read write" as they get copied to the "user_local" home directory. Googling around has not yielded anything that would indicate that this is possible via the Snow Leopard permission system. Question 1: Is this in fact possible via the permission system? If so, how? Question 2: If not possible, how would one go about solving this problem? I imagine this to be a fairly common use case so there must be a workable solution for it out there. Thanks.

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