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• How to handle product ratings in a database

  - by Mel

  Hello, I would like to know what is the best approach to storing product ratings in a database. I have in mind the following two (simplified, and assuming a MySQL db) scenarios: Scenario 1: Create two columns in the product table to store number of votes and the sum of all votes. Use columns to get an average on the product display page: products(productedID, productName, voteCount, voteSum) Pros: I will only need to access one table, and thus execute one query to display product data and ratings. Cons: Write operations will be executed in a table whose original purpose is only to furnish product data. Scenario 2: Create an additional table to store ratings. products(productID, productName) ratings(productID, voteCount, voteSum) Pros: Isolate ratings into a separate table, leaving the products table to furnish data on available products. Cons: I will have to execute two separate queries on product page requests (one for data and another for ratings). In terms of performance, which of the following two approaches is best: Allow users to execute an occasional write query to a table that will handle hundreds of read requests? Execute two queries at every product page, but isolate the write query into a separate table. I'm a novice to database development, and often find myself struggling with simple questions such as these. Many thanks,

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• Is there such a thing as a MemberExpression that handles a many-to-many relationship?

  - by Jaxidian

  We're trying to make it easy to write strongly-typed code in all areas of our system, so rather than setting var sortColumn = "FirstName" we'd like to say sortOption = (p => p.FirstName). This works great if the sortOption is of type Expression<Func<Person, object>> (we actually use generics in our code but that doesn't matter). However, we run into problems for many-to-many relationships because this notation breaks down. Consider this simple code: internal class Business { public IQueryable<Address> Addresses { get; set; } public string Name { get; set; } } internal class Address { public State MyState { get; set; } } internal class State { public string Abbreviation { get; set; } public int StateID { get; set; } } Is it possible to have this sort of MemberExpression to identify the StateID column off of a business? Again, the purpose of using this is not to return a StateID object, it's to just identify that property off of that entity (for sorting, filtering, and other purposes). It SEEMS to me that there should be some way to do this, even if it's not quite as pretty as foo = business.Addresses.SomeExtension(a => a.State.StateID);. Is this really possible? If more background is needed, take a look at this old question of mine. We've since updated the code significantly, but this should give you the general detailed idea of the context behind this question.

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• Figure and figcaption figures shrink images

  - by Why Not

  I'm attempting to use the figure and figcaption tags to varying success. Someone suggested a great CSS method to get rid of the figure margin and also link up the caption with the image. The problem: all images shrink to an extremely small size. Not sure how to rectify this. These are user-submitted images using Django so they vary in size. But currently, using these fixes, all of these shrink with a caption that does fit the image but defeats the purpose as it results in a tiny image with a caption with an even width. {% if story.pic %} <h2>Image</h2> <figure> <img class="image"src="{{ story.pic.url }}" alt="some_image_alt_text"/> {% if story.caption %} <figcaption>{{story.caption}}</figcaption> {% endif %} </figure> {% endif %} figure {margin:0; display:table; width:1px;} figcaption {display:table-row;}

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• Questions about shifting from mysql to PDO

  - by Scarface

  Hey guys I have recently decided to switch all my current plain mysql queries performed with php mysql_query to PDO style queries to improve performance, portability and security. I just have some quick questions for any experts in this database interaction tool Will it prevent injection if all statements are prepared? (I noticed on php.net it wrote 'however, if other portions of the query are being built up with unescaped input, SQL injection is still possible' I was not exactly sure what this meant). Does this just mean that if all variables are run through a prepare function it is safe, and if some are directly inserted then it is not? Currently I have a connection at the top of my page and queries performed during the rest of the page. I took a look at PDO in more detail and noticed that there is a try and catch procedure for every query involving a connection and the closing of that connection. Is there a straightforward way to connecting and then reusing that connection without having to put everything in a try or constantly repeat the procedure by connecting, querying and closing? Can anyone briefly explain in layman's terms what purpose a set_exception_handler serves? I appreciate any advice from any more experienced individuals.

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• Dynamic function arguments in C++, possible?

  - by Jeshwanth Kumar N K

  I am little new to C++, I have one doubt in variable argument passing. As I mentioned in a sample code below ( This code won't work at all, just for others understanding of my question I framed it like this), I have two functions func with 1 parameter and 2 parameters(parameter overloading). I am calling the func from main, before that I am checking whether I needs to call 2 parameter or 1 parameter. Here is the problem, as I know I can call two fuctions in respective if elseif statements, but I am curious to know whether I can manage with only one function. (In below code I am passing string not int, as I mentioned before this is just for others understanding purpose. #include<iostream.h> #include <string> void func(int, int); void func(int); void main() { int a, b,in; cout << "Enter the 2 for 2 arg, 1 for 1 arg\n"; cin << in; if ( in == 2) { string pass = "a,b"; } elseif ( in == 1) { string pass = "a"; } else { return 0; } func(pass); cout<<"In main\n"<<endl; } void func(int iNum1) { cout<<"In func1 "<<iNum1<<endl; } void func(int iNum1, int iNum2) { cout<<"In func2 "<<iNum1<<" "<<iNum2<<endl; }

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• How to optimize this MYSQL table?

  - by Lost_in_code

  This is for an upcoming project. I have two tables - first one keeps tracks of photos, and the second one keeps track of the photo's rank Photos: +-------+-----------+------------------+ | id | photo | current_rank | +-------+-----------+------------------+ | 1 | apple | 5 | | 2 | orange | 9 | +-------+-----------+------------------+ The photo rank keeps changing on a regular basis and this is the table that tracks it: Ranks: +-------+-----------+----------+-------------+ | id | photo_id | ranks | timestamp | +-------+-----------+----------+-------------+ | 1 | 1 | 8 | * | | 2 | 2 | 2 | * | | 3 | 1 | 3 | * | | 4 | 1 | 7 | * | | 5 | 1 | 5 | * | | 6 | 2 | 9 | * | +-------+-----------+----------+-------------+ * = current timestamp Every rank is tracked for reporting/analysis purpose. I talked to someone who has experience in this field and he told me that storing ranks like above is the way to go. But I'm not so sure yet. The problem here is data redundancy. There are going to be tens of thousands of photos. The photo rank changes on a hourly basis (many time within minutes) for recent photos but less frequently for older photos. At this rate the table will have millions of records within months. And since I do not have experience in working with large databases, this makes me a little nervous. I thought of this: Ranks: +-------+-----------+--------------------+ | id | photo_id | ranks | +-------+-----------+--------------------+ | 1 | 1 | 8:*,3:*,7:*,5:* | | 2 | 2 | 2:*,9:* | +-------+-----------+--------------------+ * = current timestamp That means some extra code in PHP to split the rank/time (and sorting) but that looks OK to me. Is this a correct way to optimize the table for performance? What would you recommend? Any suggestions would be great.

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• Enums and inheritance

  - by devoured elysium

  I will use (again) the following class hierarchy: Event and all the following classes inherit from Event: SportEventType1 SportEventType2 SportEventType3 SportEventType4 I have originally designed the Event class like this: public abstract class Event { public abstract EventType EventType { get; } public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } with EventType being defined as: public enum EventType { Sport1, Sport2, Sport3, Sport4 } The original idea would be that each SportEventTypeX class would set its correct EventType. Now that I think of it, I think this approach is totally incorrect for two reasons: If I want to later add a new SportEventType class I will have to modify the enum If I later decide to remove one SportEventType that I feel I won't use I'm also in big trouble with the enum. I have a class variable in the Event class that makes, afterall, assumptions about the kind of classes that will inherit from it, which kinda defeats the purpose of inheritance. How would you solve this kind of situation? Define in the Event class an abstract "Description" property, having each child class implement it? Having an Attribute(Annotation in Java!) set its Description variable instead? What would be the pros/cons of having a class variable instead of attribute/annotation in this case? Is there any other more elegant solution out there? Thanks

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• jQuery variable and object caching

  - by niksy

  This is something that has been bugging me some time and every time I found myself using different solution for this. So, I have link in my document which on click creates new element with some ID. <a href="#" id="test-link">Link</a> For the purpose of easier reusing, I would like to store that new elements ID in a variable which is jQuery object var test = $('#test'); On click I append that new element on body, new element is DIV $('body').append('<div id="test"/>'); And here goes the main "problem" - if I test this new elements length with test.length it first returns 0 and later 1. But, when I test it with $('#test').length it returns 1 from the start. I suppose it is some caching mechanism and I was wondering is there better, all-around solution which will allow to store elements in variables in the start for later repurpose and in the same time work with dynamically created elements. Live, delegate, something else? What I do sometimes is create string and add it to jQuery object but I think this is just avoiding the real issue. Also, using .find() inside another jQuery object. Thanks in advance.

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• MySql: Is it reasonable to use 'view' or I would better denormalize my DB?

  - by Budda

  There is 'team_sector' table with following fields: Id, team_id, sect_id, size, level It contains few records for each 'team' entity (referenced with 'team_id' field). Each record represent sector of team's stadium (totally 8 sectors). Now it is necessary to implement few searches: by overall stadium size (SUM(size)); the best quality (SUM(level)/COUNT(*)). I could create query something like this: SELECT TS.team_id, SUM(TS.size) as OverallSize, SUM(TS.Level)/COUNT(TS.Id) AS QualityLevel FROM team_sector GROUP BY team_id ORDER BY OverallSize DESC / ORDER BY QualityLevel DESC But my concern here is that calculation for each team will be done each time on query performed. It is not too big overhead (at least now), but I would like to avoid performance issues later. I see 2 options here. The 1st one is to create 2 additional fields in 'team' table (for example) and store there OverallSize and QualityLevel fields. If information if 'sector' table is changed - update those table too (probably would be good to do that with triggers, as sector table doesn't change too often). The 2nd option is to create a view that will provide required data. The 2nd option seems much easier for me, but I don't have a lot of experience/knowledge of work with views. Q1: What is the best option from your perspective here and why? Probably you could suggest other options? Q2: Can I create view in such way that it will do calculations rarely (at least once per day)? If yes - how? Q3: Is it reasonable to use triggers for such purpose (1st option). P.S. MySql 5.1 is used, overall number of teams is around 1-2 thousand, overall number of records in sector table - overall 6-8 thousand. I understand, those numbers are pretty small, but I would like to implement the best practice here.

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• Android - How to decide wether to run a Service in a separate Process?

  - by pableu

  I am working on an Android application that collects sensor data over the course of multiple hours. For that, we have a Service that collects the Sensor Data (e.g. Acceleration, GPS, ..), does some processing and stores them remotely on a server. Currently, this Service runs in a separate process (using android:service=":background" in the manifest). This complicates the communication between the Activities and the Service, but my predecessors created the Application this way because they thought that separating the Service from the Activities would make it more stable. I would like some more factual reasons for the effort of running a separate process. What are the advantages? Does it really run more stable? Is the Service less likely to be killed by the OS (to free up resources) if it's in a separate process? Our Application uses startForeground() and friends to minimize the chance of getting killed by the OS. The Android docs are not very specific about this, the mostly state that it depends on the Application's purpose ;-) TL;DR What are objective reasons to put a long-running Service in a separate process (in Android)?

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• Is there a unique computer identifier that can be used reliably even in a virtual machine?

  - by SaUce

  I'm writing a small client program to be run on a terminal server. I'm looking for a way to make sure that it will only run on this server and in case it is removed from the server it will not function. I understand that there is no perfect way of securing it to make it impossible to ran on other platforms, but I want to make it hard enough to prevent 95% of people to try anything. The other 5% who can hack it is not my concern. I was looking at different Unique Identifiers like Processor ID, Windows Product ID, Computer GUID and other UIs. Because the terminal server is a virtual machine, I cannot locate anything that is completely unique to this machine. Any ideas on what I should look into to make this 95% secure. I do not have time or the need to make it as secure as possible because it will defeat the purpose of the application itself. I do not want to user MAC address. Even though it is unique to each machine it can be easily spoofed. As far as Microsoft Product ID, because our system team clones VM servers and we use corporate volume key, I found already two servers that I have access to that have same Product ID Number. I have no Idea how many others out there that have same Product ID By 95% and 5% I just simply wanted to illustrate how far i want to go with securing this software. I do not have precise statistics on how many people can do what. I believe I might need to change my approach and instead of trying to identify the machine, I will be better off by identifying the user and create group based permission for access to this software.

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• counter_cache not updating on the model after save

  - by sehnsucht

  I am using a counter_cache to let MySQL do some of the bookkeeping for me: class Container has_many :items end class Item belongs_to :container, :counter_cache => true end Now, if I do this: container = Container.find(57) item = Item.new item.container = container item.save in the SQL log there will be an INSERT followed by something like: UPDATE `containers` SET `items_count` = COALESCE(`items_count`, 0) + 1 WHERE `containers`.`id` = 57 which is what I expected it to do. However, the container[:items_count] will be stale! ...unless I container.reload to pick up the updated value. Which in my mind sort of defeats part of the purpose of using the :counter_cache in favor of a custom built one, especially since I may not actually want a reload before I try to access the items_count attribute. (My models are pretty code-heavy because of the nature of the domain logic, so I sometimes have to save and create multiple things in one controller call.) I understand I can tinker with callbacks myself but this seems to me a fairly basic expectation of the simple feature. Again, if I have to write additional code to make it fully work, it might as well be easier to implement a custom counter. What am I doing/assuming wrong?

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• Infrastructure for high transactional system (language & hosting suggestion help)

  - by RPS

  Some of our friends (University students) are trying to develop a twitter type application, I want to plan for at least 1000 transactions per second (I know it's wishful thinking) for initial launch. This involves several people connecting and getting updates and posting (text + images) to site. In the back end db will server the data and also calculates rankings of what to push to user based on complex algorithm on the fly real-time. Our group is familiar with Java and Tomcat/MySQL. We can also easily learn/code in PHP/MySQL. What is the best suited platform for our purpose ? Though Java seem to be easy to implement for us I am afraid that hosting will be a bit difficult. I could find cloud based php hosting services (like rackspace cloudsites) at reasonable cost. Amazon EC2 is a bit over our heads to manage on day-to-day. Also any recommendation on hosting ? (PHP or Java) We don't have millions in seed money but about $20K to start with. Any advice on above or any thing in general approach is much appreciated.

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• Initializing ExportFactory using MEF

  - by Riz

  Scenario Application has multiple parts. Each part is in separate dll and implements interface IFoo All such dlls are present in same directory (plugins) The application can instantiate multiple instances of each part Below is the code snippet for the interfaces, part(export) and the import. The problem I am running into is, the "factories" object is initialized with empty list. However, if I try container.Resolve(typeof(IEnumerable< IFoo )) I do get object with the part. But that doesn't serve my purpose (point 4). Can anyone point what I am doing wrong here? public interface IFoo { string Name { get; } } public interface IFooMeta { string CompType { get; } } Implementation of IFoo in separate Dll [ExportMetadata("CompType", "Foo1")] [Export(typeof(IFoo), RequiredCreationPolicy = CreationPolicy.NonShared))] public class Foo1 : IFoo { public string Name { get { return this.GetType().ToString(); } } } Main application that loads all the parts and instantiate them as needed class PartsManager { [ImportMany] private IEnumerable<ExportFactory<IFoo, IFooMeta>> factories; public PartsManager() { IContainer container = ConstructContainer(); factories = (IEnumerable<ExportFactory<IFoo, IFooMeta>>) container.Resolve(typeof(IEnumerable<ExportFactory<IFoo, IFooMeta>>)); } private static IContainer ConstructContainer() { var catalog = new DirectoryCatalog(@"C:\plugins\"); var builder = new ContainerBuilder(); builder.RegisterComposablePartCatalog(catalog); return builder.Build(); } public IFoo GetPart(string compType) { var matchingFactory = factories.FirstOrDefault( x => x.Metadata.CompType == compType); if (factories == null) { return null; } else { IFoo foo = matchingFactory.CreateExport().Value; return foo; } } }

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• Generating an identifier for objects so that they can be added to a hashtable I have created

  - by dukenukem

  I have a hashtable base class and I am creating different type of hashtable by deriving from it. I only allow it to accept objects that implement my IHashable interface.For example - class LinearProbingHashTable<T> : HashTableBase<T> where T: IHashable { ... ... ... } interface IHashable { /** * Every IHashable implementation should provide an indentfying value for use in generating a hash key. */ int getIdentifier(); } class Car : IHashable { public String Make { get; set; } public String Model { get; set; } public String Color { get; set; } public int Year { get; set; } public int getIdentifier() { /// ??? } } Can anyone suggest a good method for generating an identifier for the car that can be used by the hash function to place it in the hash table? I am actually really looking for a general purpose solution to generating an id for any given class. I would like to have a base class for all classes, HashableObject, that implements IHashable and its getIdentifier method. So then I could just derive from HashableObject which would automatically provide an identifier for any instances. Which means I wouldn't have to write a different getIdentifier method for every object I add to the hashtable. public class HashableObject : IHashable { public int getIdentifier() { // Looking for code here that would generate an id for any object... } } public class Dog : HashableObject { // Dont need to implement getIdentifier because the parent class does it for me }

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• Image switch based on if a layer is visible

  - by Zuno

  I have a website that contains multiple pages as layers (not as separate HTML files). I have three images: <img src="image1.png" onclick="showlayer(1);return false;" /> <br /> <img src="image2.png" onclick="showlayer(2);return false;" /> <br /> <img src="image3.png" onclick="showlayer(3);return false;" /> When an image is clicked, it shows the relevant layer and hides the others. I want it to also change the image to image1_active.png / image2_active.png / image3_active.png depending on which layer is visible (not via the onclick event handler). Why not via the onclick event handler?... Layer 1 is set as visible by default in the CSS, so image1 needs to be image1_active.png by default too - since the user has not had to click on anything yet, this is why I need the image switch to detect the layer's visibility/display to change the image. The showlayer script is: function showlayer(n){ for(i=1;i<=3;i++){document.getElementById("layer"+i).style.display="none";document.getElementById("layer"+n).style.display="block"; }} Is it possible to adapt this script for this purpose? thank you

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• MailEnable - Configuring TLS for secure SMTP (Gmail)

  - by Buckers

  I have the latest version of MailEnable Pro installed on a new server that I'm setting up. Sending & receiving works fine with a new email account that I have set up, however I am now trying to configure GMail to use the mailserver for outgoing SMTP. I've done the following so far: Creating a self-cert SSL certficiate Ticked "Enable TLS" on the General tab of the SMTP connector properties Ticked "Send using TLS if remote server supports it" on the Outbound tab of the SMTP connector properties Selected the new self-cert SSL certificate on the SSL tab of the localhost server properties. Given permissions to IME_System on the new certificate However, Gmail is still giving me the following error: Authentication failed. Please check your username/password. [Server response: 454 TLS not available due to temporary reason code(454) ] I'm trying to connect on port 25, (someone told me you can still do this and you dont have to connect on 465). Is this right? Or do I need to tell MailEnable to use port 465? Am I missing something? Thanks, Chris.

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• Want to use something like Citrix XenClient, Free Alternative?

  - by Chris

  I'm looking to go into IT, general office server management, and it looks like XenClient would be a awesome tool to use. If I get it right, you would store a central image of the OS you want to deploy (in an iso file) on the main server. Then use XenClient to pull that image down to the client, and it will then boot the OS inside of the virtual machine. Does it download the image of the OS and store it locally (like cloning the VM onto the client?) I'd love to find a free (possibly open source?) alternative to this, I keep on hearing about KVM in Linux and PXE booting a minimalistic OS to use remote KVMs.... Would that be what I'm looking for? Ideally, I'd like a system.. - That allows me to manage one central image for multiple clients (virtualized hardware) - Easily push a new VM onto the client for easy updating. - Be able to keep files in sync (but that might be a samba / active directory's job) Would those things be possible with some kind of free alternative? Some guidance would be greatly appreciated.

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• Outlook 2007 unable to connect to exchange server

  - by mattwarren

  I came into the office a week ago and outlook has refused to connect ever since, it just says "Disconnected" in the bottom right-hand corner. I've tried restarting it, rebooting Windows etc. I'm the only one if our office who is having this problem, so it's not a general problem with the server. Things I've tried Pinging the server via IP address and host name, both work fine Connecting via OWA, this works using the same machine name Connecting to Exchange via HTTP ("Outlook Anywhere") doesn't work None of the suggestions in this question helped, http://serverfault.com/questions/21755/can-ping-exchange-server-cant-connect-outlook-to-it Disabling Windows firewall on my laptop also has no effect. There are no items in the event viewer that indicate that anything it up. Also no permissions have changed on the server since when it worked. Update: I've just tried logging onto a completely different PC, using my domain controller user-name/password. When I setup outlook on there it also fails, so the problem isn't specific to 1 pc/outlook it's something about my particular user name, but not when using OWA? What else can I do to diagnose this, any suggestions?

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• Occasional disk I/O errors in SQLite

  - by Alix Axel

  I have a very simple website running PHP and SQLite 3.7.9 (with PDO). After establishing the SQLite connection I immediately execute the following queries: PRAGMA busy_timeout=0; PRAGMA cache_size=8192; PRAGMA foreign_keys=ON; PRAGMA journal_size_limit=67110000; PRAGMA legacy_file_format=OFF; PRAGMA page_size=4096; PRAGMA recursive_triggers=ON; PRAGMA secure_delete=ON; PRAGMA synchronous=NORMAL; PRAGMA temp_store=MEMORY; PRAGMA journal_mode=WAL; PRAGMA wal_autocheckpoint=4096; This website only has one writer and a few occasional readers, so I don't expect any concurrency problems (and I'm even using WAL). Every couple of days, I've seen this error being reported by PHP: Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000]: General error: 10 disk I/O error' in ... Stack trace: #0 ...: PDO-exec('PRAGMA cache_si...') There are several things that make this error very weird to me: it's not a transient problem - no matter how many times I refresh the page, it won't go away the database file is not corrupted - the sqlite3 executable can open the database without problems If the following pragmas are commented out, PHP stops throwing the disk I/O exception: PRAGMA cache_size=8192; PRAGMA synchronous=NORMAL; PRAGMA journal_mode=WAL; Then, after successfully reconnecting to the database, I'm able to reintroduce these pragmas and the code with run smoothly for days - until eventually, the same error will occur without any apparent reason. I wasn't able to reproduce this error so far, so I'm clueless about the origin of it. I'm really curious what may be causing this problem... Any ideas? Environment: Ubuntu Server 12.04 LTS PHP 5.4.15 SQLite 3.7.9 Database size: ? 10MiB Transaction (write) size: ? 1KiB EDIT: Might these symptoms have something to do with busy_timeout?

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• Configuring external SMTP server on Azure VM - messages staying in queue

  - by Steph Locke

  I have an external SMTP provider: auth.smtp.1and1.co.uk I am trying to send SQL Server Reporting Services emails via this on an Windows 2012 Azure VM. It is configured sufficiently correctly for emails to be generated, but I've not configured something or mis-configured something as the emails then stay in the queue. Setup details Configured SMTP Virtual Server General: IP Address: Fixed value Access: Access Control: Authentication: ticked Anonymous access Access: Connection Control: All except the list below (which is empty) Access: relay restrictions: Only the list below (which contains 127.0.0.1), ticked 'allow all..' option Delivery: Outbound Security...:Basic Authentication with username and password completed, ticked TLS encryption Delivery: Outbound connections...:TCP port=587 Delivery: Advanced: FQDN=ServerName, smarthost=auth.smtp.1and1.co.uk I then set the following SSRS rsreportserver.config values: <SMTPServer>100.92.192.3</SMTPServer> <SendUsing>2</SendUsing> <SMTPServerPickupDirectory> c:\inetpub\mailroot\pickup </SMTPServerPickupDirectory> <From>[email protected]</From> Tried so far 1) turning the smtp service off and on again (just in case) 2) run SMTPDiag with no errors (also no emails) 3) tried turning off the firewall for the ports (and more generally to see if it made a difference) 4) tried generation from powershell which resulted with message in queue 5) added 25 and 857 as endpoint 6) perused the event log and found some warnings that appear to be about the recipient Message delivery to the remote domain 'gmail.com' failed for the following reason: Unable to bind to the destination server in DNS. Message delivery to the host '212.227.15.179' failed while delivering to the remote domain 'gmail.com' for the following reason: The remote server did not respond to a connection attempt. 7) tried pinging but this appears to be blocked on azure 8) tried more powershell sending on different domains variants (localhost, boxname, internal ip used in smtp properties, 127.0.0.1) - none resulting in success 9) tried adding a remote domain - no change Could anyone recommend what step 10 should be in fixing this issue please?

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• BSOD Dump - EXCEPTION_DOUBLE_FAULT - ON Windows 2008 Server 64bit

  - by Mark K

  Hello, my windows 2008 server (datacenter ed) 64bit , have recently created a series of BSOD on a different applications. the error message is in general EXCEPTION_DOUBLE_FAULT. Can anyone please help with the analysis of the dump file bellow- Best regards, Mark 2: kd !analyze -v * Bugcheck Analysis * * UNEXPECTED_KERNEL_MODE_TRAP (7f) This means a trap occurred in kernel mode, and it's a trap of a kind that the kernel isn't allowed to have/catch (bound trap) or that is always instant death (double fault). The first number in the bugcheck params is the number of the trap (8 = double fault, etc) Consult an Intel x86 family manual to learn more about what these traps are. Here is a portion of those codes: If kv shows a taskGate use .tss on the part before the colon, then kv. Else if kv shows a trapframe use .trap on that value Else .trap on the appropriate frame will show where the trap was taken (on x86, this will be the ebp that goes with the procedure KiTrap) Endif kb will then show the corrected stack. Arguments: Arg1: 0000000000000008, EXCEPTION_DOUBLE_FAULT Arg2: 0000000080050033 Arg3: 00000000000006f8 Arg4: fffff800018b1678 Debugging Details: BUGCHECK_STR: 0x7f_8 CUSTOMER_CRASH_COUNT: 1 DEFAULT_BUCKET_ID: DRIVER_FAULT_SERVER_MINIDUMP PROCESS_NAME: CustomerService. CURRENT_IRQL: 1 EXCEPTION_RECORD: fffffa6004e45568 -- (.exr 0xfffffa6004e45568) ExceptionAddress: fffff800018a0150 (nt!RtlVirtualUnwind+0x0000000000000250) ExceptionCode: 10000004 ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 0000000000000000 Parameter[1]: 00000000000000d8 TRAP_FRAME: fffffa6004e45610 -- (.trap 0xfffffa6004e45610) NOTE: The trap frame does not contain all registers. Some register values may be zeroed or incorrect. rax=0000000000000050 rbx=0000000000000000 rcx=0000000000000004 rdx=00000000000000d8 rsi=0000000000000000 rdi=0000000000000000 rip=fffff800018a0150 rsp=fffffa6004e457a0 rbp=fffffa6004e459e0 r8=0000000000000006 r9=fffff8000181e000 r10=ffffffffffffff88 r11=fffff80001a1c000 r12=0000000000000000 r13=0000000000000000 r14=0000000000000000 r15=0000000000000000 iopl=0 nv up ei pl zr na po nc nt!RtlVirtualUnwind+0x250: fffff800018a0150 488b02 mov rax,qword ptr [rdx] ds:00000000000000d8=???????????????? Resetting default scope LAST_CONTROL_TRANSFER: from fffff800018781ee to fffff80001878450 STACK_TEXT: fffffa6001768a68 fffff800018781ee : 000000000000007f 0000000000000008 0000000080050033 00000000000006f8 : nt!KeBugCheckEx fffffa6001768a70 fffff80001876a38 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt!KiBugCheckDispatch+0x6e fffffa6001768bb0 fffff800018b1678 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt!KiDoubleFaultAbort+0xb8 fffffa6004e44e30 fffff800018782a9 : fffffa6004e45568 0000000000000001 fffffa6004e45610 000000000000023b : nt!KiDispatchException+0x34 fffffa6004e45430 fffff800018770a5 : 0000000000000000 0000000000000000 0000000000000000 0000000000000001 : nt!KiExceptionDispatch+0xa9 fffffa6004e45610 fffff800018a0150 : fffffa6004e46638 fffffa6004e46010 fffff80001965190 fffff8000181e000 : nt!KiPageFault+0x1e5 fffffa6004e457a0 fffff800018a3f78 : fffffa6000000001 0000000000000000 0000000000000000 ffffffffffffff88 : nt!RtlVirtualUnwind+0x250 fffffa6004e45810 fffff800018b1706 : fffffa6004e46638 fffffa6004e46010 fffffa6000000000 0000000000000000 : nt!RtlDispatchException+0x118 fffffa6004e45f00 0000000000000000 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt!KiDispatchException+0xc2 STACK_COMMAND: kb FOLLOWUP_IP: nt!KiDoubleFaultAbort+b8 fffff800`01876a38 90 nop SYMBOL_STACK_INDEX: 2 SYMBOL_NAME: nt!KiDoubleFaultAbort+b8 FOLLOWUP_NAME: MachineOwner MODULE_NAME: nt IMAGE_NAME: ntkrnlmp.exe DEBUG_FLR_IMAGE_TIMESTAMP: 4a7801eb FAILURE_BUCKET_ID: X64_0x7f_8_nt!KiDoubleFaultAbort+b8 BUCKET_ID: X64_0x7f_8_nt!KiDoubleFaultAbort+b8 Followup: MachineOwner

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• FreeBSD performance tuning. Sysctls, loader.conf, kernel.

  - by SaveTheRbtz

  I wanted to share knowledge of tuning FreeBSD via sysctls, so i'm posting them with comments. Based on Igor Sysoev (author of nginx) presentation about FreeBSD tuning up to 100,000-200,000 active connections. Sysctls are for 7.x FreeBSD. Since 7.2 amd64 some of them are tuned well by default. Prior 7.0 some of them are boot only (set via /boot/loader.conf) or does not exist at all. Highload web server sysctls: # Max. backlog size kern.ipc.somaxconn=4096 # Shared memory // 7.2+ can use shared memory > 2Gb kern.ipc.shmmax=2147483648 # Sockets kern.ipc.maxsockets=204800 # Do not use lager sockbufs on 8.0 # ( http://old.nabble.com/Significant-performance-regression-for-increased-maxsockbuf-on-8.0-RELEASE-tt26745981.html#a26745981 ) kern.ipc.maxsockbuf=262144 # Recive clusters (on amd64 7.2+ 65k is default) # For such high value vm.kmem_size must be increased to 3G #kern.ipc.nmbclusters=229376 # Jumbo pagesize(4k/8k) clusters # Used as general packet storage for jumbo frames # can be monitored via `netstat -m` #kern.ipc.nmbjumbop=192000 # Jumbo 9k/16k clusters # If you are using them #kern.ipc.nmbjumbo9=24000 #kern.ipc.nmbjumbo16=10240 # Every socket is a file, so increase them kern.maxfiles=204800 kern.maxfilesperproc=200000 kern.maxvnodes=200000 # Turn off receive autotuning #net.inet.tcp.recvbuf_auto=0 # Small receive space, only usable on http-server, on file server this # should be increased to 65535 or even more #net.inet.tcp.recvspace=8192 # Small send space is useful for http servers that serve small files # Autotuned since 7.x net.inet.tcp.sendspace=16384 # This should be enabled if you going to use big spaces (>64k) #net.inet.tcp.rfc1323=1 # Turn this off on highspeed, lossless connections (LAN 1Gbit+) #net.inet.tcp.delayed_ack=0 # This feature is useful if you are serving data over modems, Gigabit Ethernet, # or even high speed WAN links (or any other link with a high bandwidth delay product), # especially if you are also using window scaling or have configured a large send window. # You can try setting it to 0 on fileserver with 1GBit+ interfaces # Automatically disables on small RTT ( http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/netinet/tcp_subr.c?#rev1.237 ) #net.inet.tcp.inflight.enable=0 # Disable randomizing of ports to avoid false RST # Before usage check SA here www.bsdcan.org/2006/papers/ImprovingTCPIP.pdf # (it's also says that port randomization auto-disables at some conn.rates, but I didn't tested it thou) #net.inet.ip.portrange.randomized=0 # Increase portrange # For outgoing connections only. Good for seed-boxes and ftp servers. net.inet.ip.portrange.first=1024 net.inet.ip.portrange.last=65535 # Security net.inet.ip.redirect=0 net.inet.ip.sourceroute=0 net.inet.ip.accept_sourceroute=0 net.inet.icmp.maskrepl=0 net.inet.icmp.log_redirect=0 net.inet.icmp.drop_redirect=1 net.inet.tcp.drop_synfin=1 # Security net.inet.udp.blackhole=1 net.inet.tcp.blackhole=2 # Increases default TTL, sometimes useful # Default is 64 net.inet.ip.ttl=128 # Lessen max segment life to conserve resources # ACK waiting time in miliseconds (default: 30000 from RFC) net.inet.tcp.msl=5000 # Max bumber of timewait sockets net.inet.tcp.maxtcptw=40960 # Don't use tw on local connections # As of 15 Apr 2009. Igor Sysoev says that nolocaltimewait has some buggy realization. # So disable it or now till get fixed #net.inet.tcp.nolocaltimewait=1 # FIN_WAIT_2 state fast recycle net.inet.tcp.fast_finwait2_recycle=1 # Time before tcp keepalive probe is sent # default is 2 hours (7200000) #net.inet.tcp.keepidle=60000 # Should be increased until net.inet.ip.intr_queue_drops is zero net.inet.ip.intr_queue_maxlen=4096 # Interrupt handling via multiple CPU, but with context switch. # You can play with it. Default is 1; #net.isr.direct=0 # This is for routers only #net.inet.ip.forwarding=1 #net.inet.ip.fastforwarding=1 # This speed ups dummynet when channel isn't saturated net.inet.ip.dummynet.io_fast=1 # Increase dummynet(4) hash #net.inet.ip.dummynet.hash_size=2048 #net.inet.ip.dummynet.max_chain_len # Should be increased when you have A LOT of files on server # (Increase until vfs.ufs.dirhash_mem becames lower) vfs.ufs.dirhash_maxmem=67108864 # Explicit Congestion Notification (see http://en.wikipedia.org/wiki/Explicit_Congestion_Notification) net.inet.tcp.ecn.enable=1 # Flowtable - flow caching mechanism # Useful for routers #net.inet.flowtable.enable=1 #net.inet.flowtable.nmbflows=65535 # Extreme polling tuning #kern.polling.burst_max=1000 #kern.polling.each_burst=1000 #kern.polling.reg_frac=100 #kern.polling.user_frac=1 #kern.polling.idle_poll=0 # IPFW dynamic rules and timeouts tuning # Increase dyn_buckets till net.inet.ip.fw.curr_dyn_buckets is lower net.inet.ip.fw.dyn_buckets=65536 net.inet.ip.fw.dyn_max=65536 net.inet.ip.fw.dyn_ack_lifetime=120 net.inet.ip.fw.dyn_syn_lifetime=10 net.inet.ip.fw.dyn_fin_lifetime=2 net.inet.ip.fw.dyn_short_lifetime=10 # Make packets pass firewall only once when using dummynet # i.e. packets going thru pipe are passing out from firewall with accept #net.inet.ip.fw.one_pass=1 # shm_use_phys Wires all shared pages, making them unswappable # Use this to lessen Virtual Memory Manager's work when using Shared Mem. # Useful for databases #kern.ipc.shm_use_phys=1 /boot/loader.conf: # Accept filters for data, http and DNS requests # Usefull when your software uses select() instead of kevent/kqueue or when you under DDoS # DNS accf available on 8.0+ accf_data_load="YES" accf_http_load="YES" accf_dns_load="YES" # Async IO system calls aio_load="YES" # Adds NCQ support in FreeBSD # WARNING! all ad[0-9]+ devices will be renamed to ada[0-9]+ # 8.0+ only #ahci_load= #siis_load= # Increase kernel memory size to 3G. # # Use ONLY if you have KVA_PAGES in kernel configuration, and you have more than 3G RAM # Otherwise panic will happen on next reboot! # # It's required for high buffer sizes: kern.ipc.nmbjumbop, kern.ipc.nmbclusters, etc # Useful on highload stateful firewalls, proxies or ZFS fileservers # (FreeBSD 7.2+ amd64 users: Check that current value is lower!) #vm.kmem_size="3G" # Older versions of FreeBSD can't tune maxfiles on the fly #kern.maxfiles="200000" # Useful for databases # Sets maximum data size to 1G # (FreeBSD 7.2+ amd64 users: Check that current value is lower!) #kern.maxdsiz="1G" # Maximum buffer size(vfs.maxbufspace) # You can check current one via vfs.bufspace # Should be lowered/upped depending on server's load-type # Usually decreased to preserve kmem # (default is 200M) #kern.maxbcache="512M" # Sendfile buffers # For i386 only #kern.ipc.nsfbufs=10240 # syncache Hash table tuning net.inet.tcp.syncache.hashsize=1024 net.inet.tcp.syncache.bucketlimit=100 # Incresed hostcache net.inet.tcp.hostcache.hashsize="16384" net.inet.tcp.hostcache.bucketlimit="100" # TCP control-block Hash table tuning net.inet.tcp.tcbhashsize=4096 # Enable superpages, for 7.2+ only # Also read http://lists.freebsd.org/pipermail/freebsd-hackers/2009-November/030094.html vm.pmap.pg_ps_enabled=1 # Usefull if you are using Intel-Gigabit NIC #hw.em.rxd=4096 #hw.em.txd=4096 #hw.em.rx_process_limit="-1" # Also if you have ALOT interrupts on NIC - play with following parameters # NOTE: You should set them for every NIC #dev.em.0.rx_int_delay: 250 #dev.em.0.tx_int_delay: 250 #dev.em.0.rx_abs_int_delay: 250 #dev.em.0.tx_abs_int_delay: 250 # There is also multithreaded version of em drivers can be found here: # http://people.yandex-team.ru/~wawa/ # # for additional em monitoring and statistics use # `sysctl dev.em.0.stats=1 ; dmesg` # #Same tunings for igb #hw.igb.rxd=4096 #hw.igb.txd=4096 #hw.igb.rx_process_limit=100 # Some useful netisr tunables. See sysctl net.isr #net.isr.defaultqlimit=4096 #net.isr.maxqlimit: 10240 # Bind netisr threads to CPUs #net.isr.bindthreads=1 # Nicer boot logo =) loader_logo="beastie" And finally here is my additions to GENERIC kernel # Just some of them, see also # cat /sys/{i386,amd64,}/conf/NOTES # This one useful only on i386 #options KVA_PAGES=512 # You can play with HZ in environments with high interrupt rate (default is 1000) # 100 is for my notebook to prolong it's battery life #options HZ=100 # Polling is goot on network loads with high packet rates and low-end NICs # NB! Do not enable it if you want more than one netisr thread #options DEVICE_POLLING # Eliminate datacopy on socket read-write # To take advantage with zero copy sockets you should have an MTU of 8K(amd64) # (4k for i386). This req. is only for receiving data. # Read more in man zero_copy_sockets #options ZERO_COPY_SOCKETS # Support TCP sign. Used for IPSec options TCP_SIGNATURE options IPSEC # This ones can be loaded as modules. They described in loader.conf section #options ACCEPT_FILTER_DATA #options ACCEPT_FILTER_HTTP # Adding ipfw, also can be loaded as modules options IPFIREWALL options IPFIREWALL_VERBOSE options IPFIREWALL_VERBOSE_LIMIT=10 options IPFIREWALL_DEFAULT_TO_ACCEPT options IPFIREWALL_FORWARD # Adding kernel NAT options IPFIREWALL_NAT options LIBALIAS # Traffic shaping options DUMMYNET # Divert, i.e. for userspace NAT options IPDIVERT # This is for OpenBSD's pf firewall device pf device pflog # pf's QoS - ALTQ options ALTQ options ALTQ_CBQ # Class Bases Queuing (CBQ) options ALTQ_RED # Random Early Detection (RED) options ALTQ_RIO # RED In/Out options ALTQ_HFSC # Hierarchical Packet Scheduler (HFSC) options ALTQ_PRIQ # Priority Queuing (PRIQ) options ALTQ_NOPCC # Required for SMP build # Pretty console # Manual can be found here http://forums.freebsd.org/showthread.php?t=6134 #options VESA #options SC_PIXEL_MODE # Disable reboot on Ctrl Alt Del #options SC_DISABLE_REBOOT # Change normal|kernel messages color options SC_NORM_ATTR=(FG_GREEN|BG_BLACK) options SC_KERNEL_CONS_ATTR=(FG_YELLOW|BG_BLACK) # More scroll space options SC_HISTORY_SIZE=8192 # Adding hardware crypto device device crypto device cryptodev # Useful network interfaces device vlan device tap #Virtual Ethernet driver device gre #IP over IP tunneling device if_bridge #Bridge interface device pfsync #synchronization interface for PF device carp #Common Address Redundancy Protocol device enc #IPsec interface device lagg #Link aggregation interface device stf #IPv4-IPv6 port # Also for my notebook, but may be used with Opteron #device amdtemp # Support for ECMP. More than one route for destination # Works even with default route so one can use it as LB for two ISP # For now code is unstable and panics (panic: rtfree 2) on route deletions. #options RADIX_MPATH # Multicast routing #options MROUTING #options PIM # DTrace options KDTRACE_HOOKS # all architectures - enable general DTrace hooks options DDB_CTF # all architectures - kernel ELF linker loads CTF data #options KDTRACE_FRAME # amd64-only # Adaptive spining in lockmgr (8.x+) # See http://www.mail-archive.com/[email protected]/msg10782.html options ADAPTIVE_LOCKMGRS # UTF-8 in console (9.x+) #options TEKEN_UTF8 #options TEKEN_XTERM # NCQ support # WARNING! all ad[0-9]+ devices will be renamed to ada[0-9]+ #options ATA_CAM # FreeBSD 9+ # Deadlock resolver thread # For additional information see http://www.mail-archive.com/[email protected]/msg18124.html #options DEADLKRES PS. Also most of FreeBSD's limits can be monitored by # vmstat -z and # limits PPS. variety of network counters can be monitored via # netstat -s In FreeBSD-9 netstat's -Q option appeared, try following command to display netisr stats # netstat -Q PPPS. also see # man 7 tuning PPPPS. I wanted to thank FreeBSD community, especially author of nginx - Igor Sysoev, nginx-ru@ and FreeBSD-performance@ mailing lists for providing useful information about FreeBSD tuning. So here is the question: What tunings are you using on yours FreeBSD servers? You can also post your /etc/sysctl.conf, /boot/loader.conf, kernel options, etc with description of its' meaning (do not copy-paste from sysctl -d). Don't forget to specify server type (web, smb, gateway, etc) Let's share experience!

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• Lenovo Mini Wireless Keyboard N5901: Remap orange "My Computer" button

  - by Jon Schneider

  I have a Lenovo Mini Wireless Keyboard N5901 (a.k.a. Part No. 57Y6336) that I'm using with an HTPC running Windows 7. The remote comes with an orange button in the top-left corner that by default, when pressed, opens the Windows "My Computer" window. I would like to remap / reprogram this button to act like the green "Windows Media Center" button instead on a Windows Media Center (WMC) remote; that is, open Windows Media Center if it isn't already open, or go to the WMC homepage if WMC is already open. I've tried several keyboard-remapping utilities (as recommended in other, more general "how to remap keyboard key?" SuperUser.com questions) including SharpKeys, Key Mapper, and KeyTweak, with no luck so far. None of these utilities recognize the orange button -- they all do recognize that some key was pressed, but display a value for the key of "unsupported" or something similar. I was able to use a utility called Keyboard Scan Code Generator to determine that a press of the orange button has a KeyData value of 16777217 (0x1000001), and a "Virtual Code" value of 182. (The other "media" buttons on the N5901 have the same KeyData value, but different Virtual Code values). I'm not sure at this point where in Windows this keystroke is being interpreted as a command to open "My Computer." There is no special software / driver for this device; it worked out of the box with Windows 7, no special driver install necessary. Is there any way to accomplish this? Thanks in advance for any suggestions!

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• Over 200 active requests like "OPTIONS * HTTP/1.0" 200 - "-" "Apache (internal dummy connection)"

  - by Stefan Lasiewski

  Some details: Webserver: Apache/2.2.13 (FreeBSD) mod_ssl/2.2.13 OpenSSL/0.9.8e OS: FreeBSD 7.2-RELEASE This is a FreeBSD Jail. I believe I use the Apache 'prefork' MPM (I run the default for FreeBSD). I use the default values for MaxClients (256) I have enabled mod_status, with "ExtendedStatus On". When I view /server-status , I see a handful of regular requests. I also see over 230 requests from the 'localhost', like these: 37-0 - 0/0/1 . 0.00 1510 0 0.0 0.00 0.00 127.0.0.2 www.example.gov OPTIONS * HTTP/1.0 38-0 - 0/0/1 . 0.00 1509 0 0.0 0.00 0.00 127.0.0.2 www.example.gov OPTIONS * HTTP/1.0 39-0 - 0/0/3 . 0.00 1482 0 0.0 0.00 0.00 127.0.0.2 www.example.gov OPTIONS * HTTP/1.0 40-0 - 0/0/6 . 0.00 1445 0 0.0 0.00 0.00 127.0.0.2 www.example.gov OPTIONS * HTTP/1.0 I also see about 2417 requests yesterday from the localhost, like these: Apr 14 11:16:40 192.168.16.127 httpd[431]: www.example.gov 127.0.0.2 - - [15/Apr/2010:11:16:40 -0700] "OPTIONS * HTTP/1.0" 200 - "-" "Apache (internal dummy connection)" The page at http://wiki.apache.org/httpd/InternalDummyConnection says "These requests are perfectly normal and you do not, in general, need to worry about them", but I'm not so sure. Why are there over 230 of these? Are these active connections? If I have "MaxClients 256", and over 230 of these connections, it seems that my webserver is dangerously close to running out of available connections. It also seems like Apache should only need a handful of these "internal dummy connections" We actually had two unexplained outages last night, and I am wondering if these "internal dummy connection" caused us to run out of available connections.

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