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  • VB.NET Two different approaches to generic cross-threaded operations; which is better?

    - by BASnappl
    VB.NET 2010, .NET 4 Hello, I recently read about using SynchronizationContext objects to control the execution thread for some code. I have been using a generic subroutine to handle (possibly) cross-thread calls for things like updating UI controls that utilizes Invoke. I'm an amateur and have a hard time understanding the pros and cons of any particular approach. I am looking for some insight on which approach might be preferable and why. Update: This question is motivated, in part, by statements such as the following from the MSDN page on Control.InvokeRequired. An even better solution is to use the SynchronizationContext returned by SynchronizationContext rather than a control for cross-thread marshaling. Method 1: Public Sub InvokeControl(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of T)) If Control.InvokeRequired Then Control.Invoke(New Action(Of T, Action(Of T))(AddressOf InvokeControl), New Object() {Control, Action}) Else Action(Control) End If End Sub Method 2: Public Sub UIAction(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of Control)) SyncContext.Send(New Threading.SendOrPostCallback(Sub() Action(Control)), Nothing) End Sub Where SyncContext is a Threading.SynchronizationContext object defined in the constructor of my UI form: Public Sub New() InitializeComponent() SyncContext = WindowsFormsSynchronizationContext.Current End Sub Then, if I wanted to update a control (e.g., Label1) on the UI form, I would do: InvokeControl(Label1, Sub(x) x.Text = "hello") or UIAction(Label1, Sub(x) x.Text = "hello") So, what do y'all think? Is one way preferred or does it depend on the context? If you have the time, verbosity would be appreciated! Thanks in advance, Brian

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  • Generic that takes only numeric types (int double etc)?

    - by brandon
    In a program I'm working on, I need to write a function to take any numeric type (int, short, long etc) and shove it in to a byte array at a specific offset. There exists a Bitconverter.GetBytes() method that takes the numeric type and returns it as a byte array, and this method only takes numeric types. So far I have: private void AddToByteArray<T>(byte[] destination, int offset, T toAdd) where T : struct { Buffer.BlockCopy(BitConverter.GetBytes(toAdd), 0, destination, offset, sizeof(toAdd)); } So basically my goal is that, for example, a call to AddToByteArray(array, 3, (short)10) would take 10 and store it in the 4th slot of array. The explicit cast exists because I know exactly how many bytes I want it to take up. There are cases where I would want a number that is small enough to be a short to really take up 4 bytes. On the flip side, there are times when I want an int to be crunched down to just a single byte. I'm doing this to create a custom network packet, if that makes any ideas pop in to your heads. If the where clause of a generic supported something like "where T : int || long || etc" I would be ok. (And no need to explain why they don't support that, the reason is fairly obvious) Any help would be greatly appreciated! Edit: I realize that I could just do a bunch of overloads, one for each type I want to support... but I'm asking this question because I want to avoid precisely that :)

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  • WCF: get generic type object (e.g. MyObject<T>) from remote machine

    - by Aaron
    I have two applications that are communicating through WCF. On the server the following object exists: public class MyObject<T> { ... public Entry<T> GetValue() } Where Entry<T> is another object with T Data as a public property. T could be any number of types (string, double, etc) On the client I have ClientObject<T> that needs to get the value of Data from the server (same type). Since I'm using WCF, I have to define my ServiceContract as an interface, and I can't have ClientObject<T> call Entry<T> GetMyObjectValue (string Name) which calls GetValue on the correct MyObject<T> because my interface isn't aware of the type information. I've tried implementing separate GetValue functions (GetMyObjectValueDouble, GetMyObjectValueString) in the interface and then have ClientObject determine the correct one to call. However, Entry<T> val = (Entry<T>)GetMyObjectValueDouble(...); doesn't work because it's not sure about the type information. How can I go about getting a generic object over WCF with the correct type information? Let me know if there are other details I can provide. Thanks!

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  • My method is too specific. How can I make it more generic?

    - by EricBoersma
    I have a class, the outline of which is basically listed below. import org.apache.commons.math.stat.Frequency; public class WebUsageLog { private Collection<LogLine> logLines; private Collection<Date> dates; WebUsageLog() { this.logLines = new ArrayList<LogLine>(); this.dates = new ArrayList<Date>(); } SortedMap<Double, String> getFrequencyOfVisitedSites() { SortedMap<Double, String> frequencyMap = new TreeMap<Double, String>(Collections.reverseOrder()); //we reverse order to sort from the highest percentage to the lowest. Collection<String> domains = new HashSet<String>(); Frequency freq = new Frequency(); for (LogLine line : this.logLines) { freq.addValue(line.getVisitedDomain()); domains.add(line.getVisitedDomain()); } for (String domain : domains) { frequencyMap.put(freq.getPct(domain), domain); } return frequencyMap; } } The intention of this application is to allow our Human Resources folks to be able to view Web Usage Logs we send to them. However, I'm sure that over time, I'd like to be able to offer the option to view not only the frequency of visited sites, but also other members of LogLine (things like the frequency of assigned categories, accessed types [text/html, img/jpeg, etc...] filter verdicts, and so on). Ideally, I'd like to avoid writing individual methods for compilation of data for each of those types, and they could each end up looking nearly identical to the getFrequencyOfVisitedSites() method. So, my question is twofold: first, can you see anywhere where this method should be improved, from a mechanical standpoint? And secondly, how would you make this method more generic, so that it might be able to handle an arbitrary set of data?

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  • How do I cast from int to generic type Integer?

    - by Rob Kent
    I'm relatively new to Java and am used to generics in C# so have struggled a bit with this code. Basically I want a generic method for getting a stored Android preference by key and this code, albeit ugly, works for a Boolean but not an Integer, when it blows up with a ClassCastException. Can anyone tell me why this is wrong and maybe help me improve the whole routine (using wildcards?)? public static <T> T getPreference(Class<T> argType, String prefKey, T defaultValue, SharedPreferences sharedPreferences) { ... try { if (argType == Boolean.class) { Boolean def = (Boolean) defaultValue; return argType.cast(sharedPreferences.getBoolean(prefKey, def)); } else if (argType == Integer.class) { Integer def = (Integer) defaultValue; return argType.cast(sharedPreferences.getInt(prefKey, def)); } else { AppGlobal.logWarning("getPreference: Unknown type '%s' for preference '%s'. Returning default value.", argType.getName(), prefKey); return defaultValue; } } catch (ClassCastException e) { AppGlobal.logError("Cast exception when reading pref %s. Using default value.", prefKey); return defaultValue; } } I've tried various ways - using the native int, casting to an Integer, but nothing works.

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  • Saving image to the existing file throws "A generic error occurred in GDI+" error.

    - by ryan
    i am trying to create a overlapped image using different images,then saving to a particular location. so that i can use generated image(overlapped img) in my telerik reporting. it is important to me to save the overlapped image to the same location with same name. but generating this overlapped image second time throws throws "A generic error occurred in GDI+" error. Please help me with this. It seems i can not override the existing image file. i tried deleting the existing image every time i generate the new one. but its not allowing me deleting the file ,may be it is used by telerik reporting. Here is the image create method which takes the baseimage path, sectionimage path and the reportimage path (this is the target locationenter code here) public static void Creat(List<string> sectionNames, string reportImagePath, string baseImagePath) { var file = Image.FromFile(baseImagePath); Graphics g = Graphics.FromImage(file); foreach (var sectionName in sectionNames) { var image = Image.FromFile(sectionName); g.DrawImage(image, new PointF(0.0F, 0.0F)); } file.Save(reportImagePath, ImageFormat.Png); file.Dispose(); }

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  • rails + paperclip: Is a generic "Attachment" model a good idea?

    - by egarcia
    On my application I've several things with attachments on them, using paperclip. Clients have one logo. Stores can have one or more pictures. These pictures, in addition, can have other information such as the date in which they were taken. Products can have one or more pictures of them, categorized (from the font, from the back, etc). For now, each one of my Models has its own "paperclip-fields" (Client has_attached_file) or has_many models that have attached files (Store has_many StorePictures, Product has_many ProductPictures) My client has also told me that in the future we might be adding more attachments to the system (i.e. pdf documents for the clients to download). My application has a rather complex authorization system implemented with declarative_authorization. One can not, for example, download pictures from a product he's not allowed to 'see'. I'm considering re-factoring my code so I can have a generic "Attachment" model. So any model can has_many :attachments. With this context, does it sound like a good idea? Or should I continue making Foos and FooPictures?

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  • Is there a nice way of having static generic parameters is Java?

    - by Chris
    Hello, recently I'm writing some functions that I take from Haskell and translate into Java. One of the main problems I have is I cannot easily create a static property with a generic type. Let me explain by a little example... // An interface to implement functions public interface Func<P, R> { public R apply(P p); } // What I want to do... (incorrect in Java) public class ... { public static <T> Func<T, T> identity = new Func<T, T>() { public T apply(T p) { return p; } } } // What I do right now public class ... { private static Func<Object, Object> identity = new Func<Object, Object>() { public Object apply(Object p) { return p; } } @SuppressWarnings("unchecked") public static <T> Func<T, T> getIdentity() { return (Func<T, T>)identity; } } Are there any easier ways to do something like that? What kind of problems might arise if the syntax I used would be valid?

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  • How to write a generic USB Host Driver for Printers from various vendors?

    - by Ullas
    I want to develop a USB host on an embedded device that will talk to printers from various vendors. Drivers for the vendor specific printers would be available on PC which is ultimately communicating with printer but my device is facilitating this communication and needs to perform the basic handshaking/setup of the printer (i.e, it needs to know when the printer is connected, what are the socket IDs that needs to be opened for CTRL and DATA transmissions etc). All of these printers are supposed to comply with IEEE 1284.4 standards but I see that many of them vary quiet a bit. One approach I have is to take the USB traces of handshaking from each of these printers and write various sections of code respectively (I know, that sounds ridiculous!). Is there a generic way to do this? Is there any available forum where these standard informations are mentioned? For eg: EPSON uses 'EPSON-CTRL' and 'EPSON-DATA' for its control and data services which needs to be provided to get the socket ID for these services. I am pretty sure HPs, Canon's etc would have their own service names as well. As per the standards, this was supposed to be captured in IANA but I dont see anything there. Any help on this would be greatly appreciated. Thanks and regards, Ullas

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  • LLBLGen Pro feature highlights: automatic element name construction

    - by FransBouma
    (This post is part of a series of posts about features of the LLBLGen Pro system) One of the things one might take for granted but which has a huge impact on the time spent in an entity modeling environment is the way the system creates names for elements out of the information provided, in short: automatic element name construction. Element names are created in both directions of modeling: database first and model first and the more names the system can create for you without you having to rename them, the better. LLBLGen Pro has a rich, fine grained system for creating element names out of the meta-data available, which I'll describe more in detail below. First the model element related element naming features are highlighted, in the section Automatic model element naming features and after that I'll go more into detail about the relational model element naming features LLBLGen Pro has to offer in the section Automatic relational model element naming features. Automatic model element naming features When working database first, the element names in the model, e.g. entity names, entity field names and so on, are in general determined from the relational model element (e.g. table, table field) they're mapped on, as the model elements are reverse engineered from these relational model elements. It doesn't take rocket science to automatically name an entity Customer if the entity was created after reverse engineering a table named Customer. It gets a little trickier when the entity which was created by reverse engineering a table called TBL_ORDER_LINES has to be named 'OrderLine' automatically. Automatic model element naming also takes into effect with model first development, where some settings are used to provide you with a default name, e.g. in the case of navigator name creation when you create a new relationship. The features below are available to you in the Project Settings. Open Project Settings on a loaded project and navigate to Conventions -> Element Name Construction. Strippers! The above example 'TBL_ORDER_LINES' shows that some parts of the table name might not be needed for name creation, in this case the 'TBL_' prefix. Some 'brilliant' DBAs even add suffixes to table names, fragments you might not want to appear in the entity names. LLBLGen Pro offers you to define both prefix and suffix fragments to strip off of table, view, stored procedure, parameter, table field and view field names. In the example above, the fragment 'TBL_' is a good candidate for such a strip pattern. You can specify more than one pattern for e.g. the table prefix strip pattern, so even a really messy schema can still be used to produce clean names. Underscores Be Gone Another thing you might get rid of are underscores. After all, most naming schemes for entities and their classes use PasCal casing rules and don't allow for underscores to appear. LLBLGen Pro can automatically strip out underscores for you. It's an optional feature, so if you like the underscores, you're not forced to see them go: LLBLGen Pro will leave them alone when ordered to to so. PasCal everywhere... or not, your call LLBLGen Pro can automatically PasCal case names on word breaks. It determines word breaks in a couple of ways: a space marks a word break, an underscore marks a word break and a case difference marks a word break. It will remove spaces in all cases, and based on the underscore removal setting, keep or remove the underscores, and upper-case the first character of a word break fragment, and lower case the rest. Say, we keep the defaults, which is remove underscores and PasCal case always and strip the TBL_ fragment, we get with our example TBL_ORDER_LINES, after stripping TBL_ from the table name two word fragments: ORDER and LINES. The underscores are removed, the first character of each fragment is upper-cased, the rest lower-cased, so this results in OrderLines. Almost there! Pluralization and Singularization In general entity names are singular, like Customer or OrderLine so LLBLGen Pro offers a way to singularize the names. This will convert OrderLines, the result we got after the PasCal casing functionality, into OrderLine, exactly what we're after. Show me the patterns! There are other situations in which you want more flexibility. Say, you have an entity Customer and an entity Order and there's a foreign key constraint defined from the target of Order and the target of Customer. This foreign key constraint results in a 1:n relationship between the entities Customer and Order. A relationship has navigators mapped onto the relationship in both entities the relationship is between. For this particular relationship we'd like to have Customer as navigator in Order and Orders as navigator in Customer, so the relationship becomes Customer.Orders 1:n Order.Customer. To control the naming of these navigators for the various relationship types, LLBLGen Pro defines a set of patterns which allow you, using macros, to define how the auto-created navigator names will look like. For example, if you rather have Customer.OrderCollection, you can do so, by changing the pattern from {$EndEntityName$P} to {$EndEntityName}Collection. The $P directive makes sure the name is pluralized, which is not what you want if you're going for <EntityName>Collection, hence it's removed. When working model first, it's a given you'll create foreign key fields along the way when you define relationships. For example, you've defined two entities: Customer and Order, and they have their fields setup properly. Now you want to define a relationship between them. This will automatically create a foreign key field in the Order entity, which reflects the value of the PK field in Customer. (No worries if you hate the foreign key fields in your classes, on NHibernate and EF these can be hidden in the generated code if you want to). A specific pattern is available for you to direct LLBLGen Pro how to name this foreign key field. For example, if all your entities have Id as PK field, you might want to have a different name than Id as foreign key field. In our Customer - Order example, you might want to have CustomerId instead as foreign key name in Order. The pattern for foreign key fields gives you that freedom. Abbreviations... make sense of OrdNr and friends I already described word breaks in the PasCal casing paragraph, how they're used for the PasCal casing in the constructed name. Word breaks are used for another neat feature LLBLGen Pro has to offer: abbreviation support. Burt, your friendly DBA in the dungeons below the office has a hate-hate relationship with his keyboard: he can't stand it: typing is something he avoids like the plague. This has resulted in tables and fields which have names which are very short, but also very unreadable. Example: our TBL_ORDER_LINES example has a lovely field called ORD_NR. What you would like to see in your fancy new OrderLine entity mapped onto this table is a field called OrderNumber, not a field called OrdNr. What you also like is to not have to rename that field manually. There are better things to do with your time, after all. LLBLGen Pro has you covered. All it takes is to define some abbreviation - full word pairs and during reverse engineering model elements from tables/views, LLBLGen Pro will take care of the rest. For the ORD_NR field, you need two values: ORD as abbreviation and Order as full word, and NR as abbreviation and Number as full word. LLBLGen Pro will now convert every word fragment found with the word breaks which matches an abbreviation to the given full word. They're case sensitive and can be found in the Project Settings: Navigate to Conventions -> Element Name Construction -> Abbreviations. Automatic relational model element naming features Not everyone works database first: it may very well be the case you start from scratch, or have to add additional tables to an existing database. For these situations, it's key you have the flexibility that you can control the created table names and table fields without any work: let the designer create these names based on the entity model you defined and a set of rules. LLBLGen Pro offers several features in this area, which are described in more detail below. These features are found in Project Settings: navigate to Conventions -> Model First Development. Underscores, welcome back! Not every database is case insensitive, and not every organization requires PasCal cased table/field names, some demand all lower or all uppercase names with underscores at word breaks. Say you create an entity model with an entity called OrderLine. You work with Oracle and your organization requires underscores at word breaks: a table created from OrderLine should be called ORDER_LINE. LLBLGen Pro allows you to do that: with a simple checkbox you can order LLBLGen Pro to insert an underscore at each word break for the type of database you're working with: case sensitive or case insensitive. Checking the checkbox Insert underscore at word break case insensitive dbs will let LLBLGen Pro create a table from the entity called Order_Line. Half-way there, as there are still lower case characters there and you need all caps. No worries, see below Casing directives so everyone can sleep well at night For case sensitive databases and case insensitive databases there is one setting for each of them which controls the casing of the name created from a model element (e.g. a table created from an entity definition using the auto-mapping feature). The settings can have the following values: AsProjectElement, AllUpperCase or AllLowerCase. AsProjectElement is the default, and it keeps the casing as-is. In our example, we need to get all upper case characters, so we select AllUpperCase for the setting for case sensitive databases. This will produce the name ORDER_LINE. Sequence naming after a pattern Some databases support sequences, and using model-first development it's key to have sequences, when needed, to be created automatically and if possible using a name which shows where they're used. Say you have an entity Order and you want to have the PK values be created by the database using a sequence. The database you're using supports sequences (e.g. Oracle) and as you want all numeric PK fields to be sequenced, you have enabled this by the setting Auto assign sequences to integer pks. When you're using LLBLGen Pro's auto-map feature, to create new tables and constraints from the model, it will create a new table, ORDER, based on your settings I previously discussed above, with a PK field ID and it also creates a sequence, SEQ_ORDER, which is auto-assigns to the ID field mapping. The name of the sequence is created by using a pattern, defined in the Model First Development setting Sequence pattern, which uses plain text and macros like with the other patterns previously discussed. Grouping and schemas When you start from scratch, and you're working model first, the tables created by LLBLGen Pro will be in a catalog and / or schema created by LLBLGen Pro as well. If you use LLBLGen Pro's grouping feature, which allows you to group entities and other model elements into groups in the project (described in a future blog post), you might want to have that group name reflected in the schema name the targets of the model elements are in. Say you have a model with a group CRM and a group HRM, both with entities unique for these groups, e.g. Employee in HRM, Customer in CRM. When auto-mapping this model to create tables, you might want to have the table created for Employee in the HRM schema but the table created for Customer in the CRM schema. LLBLGen Pro will do just that when you check the setting Set schema name after group name to true (default). This gives you total control over where what is placed in the database from your model. But I want plural table names... and TBL_ prefixes! For now we follow best practices which suggest singular table names and no prefixes/suffixes for names. Of course that won't keep everyone happy, so we're looking into making it possible to have that in a future version. Conclusion LLBLGen Pro offers a variety of options to let the modeling system do as much work for you as possible. Hopefully you enjoyed this little highlight post and that it has given you new insights in the smaller features available to you in LLBLGen Pro, ones you might not have thought off in the first place. Enjoy!

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  • Are there any generic KVM over IP cards/chips for motherboards without any such capability?

    - by eek142
    I have a remote server that doesn't have any IP KVM capabilities, meaning I can't remotely power cycle it or access the BIOS. I saw that ASUS offers something for their motherboards here: http://www.asus.com/Server_Workstation/Accessories/ASMB5iKVM/ But is there anything like this available for other motherboards? Even something that I could stash away somewhere in a hard drive bay that simply plugs into the board would be great.

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  • Nagios notifications definitions

    - by Colin
    I am trying to monitor a web server in such a way that I want to search for a particular string on a page via http. The command is defined in command.cfg as follows # 'check_http-mysite command definition' define command { command_name check_http-mysite command_line /usr/lib/nagios/plugins/check_http -H mysite.example.com -s "Some text" } # 'notify-host-by-sms' command definition define command { command_name notify-host-by-sms command_line /usr/bin/send_sms $CONTACTPAGER$ "Nagios - $NOTIFICATIONTYPE$ :Host$HOSTALIAS$ is $HOSTSTATE$ ($OUTPUT$)" } # 'notify-service-by-sms' command definition define command { command_name notify-service-by-sms command_line /usr/bin/send_sms $CONTACTPAGER$ "Nagios - $NOTIFICATIONTYPE$: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ ($OUTPUT$)" } Now if nagios doesn't find "Some text" on the home page mysite.example.com, nagios should notify a contact via sms through the Clickatell http API which I have a script for that that I have tested and found that it works fine. Whenever I change the command definition to search for a string which is not on the page, and restart nagios, I can see on the web interface that the string was not found. What I don't understand is why isn't the notification sent though I have defined the host, hostgroup, contact, contactgroup and service and so forth. What I'm I missing, these are my definitions, In my web access through the cgi I can see that I have notifications have been defined and enabled though I don't get both email and sms notifications during hard status changes. host.cfg define host { use generic-host host_name HAL alias IBM-1 address xxx.xxx.xxx.xxx check_command check_http-mysite } *hostgroups_nagios2.cfg* # my website define hostgroup{ hostgroup_name my-servers alias All My Servers members HAL } *contacts_nagios2.cfg* define contact { contact_name colin alias Colin Y service_notification_period 24x7 host_notification_period 24x7 service_notification_options w,u,c,r,f,s host_notification_options d,u,r,f,s service_notification_commands notify-service-by-email,notify-service-by-sms host_notification_commands notify-host-by-email,notify-host-by-sms email [email protected] pager +254xxxxxxxxx } define contactgroup{ contactgroup_name site_admin alias Site Administrator members colin } *services_nagios2.cfg* # check for particular string in page via http define service { hostgroup_name my-servers service_description STRING CHECK check_command check_http-mysite use generic-service notification_interval 0 ; set > 0 if you want to be renotified contacts colin contact_groups site_admin } Could someone please tell me where I'm going wrong. Here are the generic-host and generic-service definitions *generic-service_nagios2.cfg* # generic service template definition define service{ name generic-service ; The 'name' of this service template active_checks_enabled 1 ; Active service checks are enabled passive_checks_enabled 1 ; Passive service checks are enabled/accepted parallelize_check 1 ; Active service checks should be parallelized (disabling this can lead to major performance problems) obsess_over_service 1 ; We should obsess over this service (if necessary) check_freshness 0 ; Default is to NOT check service 'freshness' notifications_enabled 1 ; Service notifications are enabled event_handler_enabled 1 ; Service event handler is enabled flap_detection_enabled 1 ; Flap detection is enabled failure_prediction_enabled 1 ; Failure prediction is enabled process_perf_data 1 ; Process performance data retain_status_information 1 ; Retain status information across program restarts retain_nonstatus_information 1 ; Retain non-status information across program restarts notification_interval 0 ; Only send notifications on status change by default. is_volatile 0 check_period 24x7 normal_check_interval 5 retry_check_interval 1 max_check_attempts 4 notification_period 24x7 notification_options w,u,c,r contact_groups site_admin register 0 ; DONT REGISTER THIS DEFINITION - ITS NOT A REAL SERVICE, JUST A TEMPLATE! } *generic-host_nagios2.cfg* define host{ name generic-host ; The name of this host template notifications_enabled 1 ; Host notifications are enabled event_handler_enabled 1 ; Host event handler is enabled flap_detection_enabled 1 ; Flap detection is enabled failure_prediction_enabled 1 ; Failure prediction is enabled process_perf_data 1 ; Process performance data retain_status_information 1 ; Retain status information across program restarts retain_nonstatus_information 1 ; Retain non-status information across program restarts max_check_attempts 10 notification_interval 0 notification_period 24x7 notification_options d,u,r contact_groups site_admin register 1 ; DONT REGISTER THIS DEFINITION - ITS NOT A REAL HOST, JUST A TEMPLATE! }

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  • Solution to route/proxy SNMP Traps (or Netflow, generic UDP, etc) for network monitoring?

    - by Christopher Cashell
    I'm implementing a network monitoring solution for a very large network (approximately 5000 network devices). We'd like to have all devices on our network send SNMP traps to a single box (technically this will probably be an HA pair of boxes) and then have that box pass the SNMP traps on to the real processing boxes. This will allow us to have multiple back-end boxes handling traps, and to distribute load among those back end boxes. One key feature that we need is the ability to forward the traps to a specific box depending on the source address of the trap. Any suggestions for the best way to handle this? Among the things we've considered are: Using snmptrapd to accept the traps, and have it pass them off to a custom written perl handler script to rewrite the trap and send it to the proper processing box Using some sort of load balancing software running on a Linux box to handle this (having some difficulty finding many load balancing programs that will handle UDP) Using a Load Balancing Appliance (F5, etc) Using IPTables on a Linux box to route the SNMP traps with NATing We've currently implemented and are testing the last solution, with a Linux box with IPTables configured to receive the traps, and then depending on the source address of the trap, rewrite it with a destination nat (DNAT) so the packet gets sent to the proper server. For example: # Range: 10.0.0.0/19 Site: abc01 Destination: foo01 iptables -t nat -A PREROUTING -p udp --dport 162 -s 10.0.0.0/19 -j DNAT --to-destination 10.1.2.3 # Range: 10.0.33.0/21 Site: abc01 Destination: foo01 iptables -t nat -A PREROUTING -p udp --dport 162 -s 10.0.33.0/21 -j DNAT --to-destination 10.1.2.3 # Range: 10.1.0.0/16 Site: xyz01 Destination: bar01 iptables -t nat -A PREROUTING -p udp --dport 162 -s 10.1.0.0/16 -j DNAT --to-destination 10.3.2.1 This should work with excellent efficiency for basic trap routing, but it leaves us completely limited to what we can mach and filter on with IPTables, so we're concerned about flexibility for the future. Another feature that we'd really like, but isn't quite a "must have" is the ability to duplicate or mirror the UDP packets. Being able to take one incoming trap and route it to multiple destinations would be very useful. Has anyone tried any of the possible solutions above for SNMP traps (or Netflow, general UDP, etc) load balancing? Or can anyone think of any other alternatives to solve this?

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  • Windows updates behind a physical firewall with only IP based rules and generic outbound connections are turned off

    - by user125245
    I have some boxes that I do not want to allow any in or outbound traffic to the internet Except for windows updates. However the fire wall in place (Cisco ASA) apparently only supports ip based rules. As best I can tell access to Microsoft updates via anything other then the half dozen URL masks the Microsoft lists as needed does not appear possible. I have kicked around building a full WSUS that I would then manually copy the update files to so that no direct Microsoft access is needed but this sounds very top heavy for the very few boxes involved. I have also kicked around manual updates all around but am not certain how to be conveniently and confidently sure that the correct updates are being applied in the correct order. Any ideas from any direction would be appreciated. I want this as simple / cost effective as possible but have very little flexibility on the only absolutely required internet access policy.

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  • What are the differences between the "generic" and "server" kernel images provided by Ubuntu?

    - by dcrosta
    In particular, I'm wondering if there are any patches or config adjustments made to the disk cache size in the server edition. I'm running on a small system (256M RAM), and would like to experiment with keeping the disk cache size smaller so that there's more memory available for applications. I've found this page at Ubuntu's website, which neither answers my questions nor is about the 9.04 release.

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  • File shares for Mac users

    - by Generic Error
    The main file shares on our network are currently hosted by old Apple XServes. I had planned to replace some of these with Windows shares as I have better hardware available but have been told this is likely to cause issues with some of our Mac users. What sort of issues am I likely to run into and what are the recommended ways of hosting general file storage in a mixed OS (Windows, OSX, occasionally linux) environment?

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  • Can I mix drive types in an HP server?

    - by Generic Error
    I currently have the following setup: HP DL380 G4 Server 6 x 73GB, Ultra160, 10k, SCSI 80 Pin Drives Smart Array 6i Controller RAID 5 One of the drives is failing and needs to be replaced. I have on hand drives that are the same size and type, but are Ultra320, 15k instead. I have verified that these drives work in another system with the same type of drive controller. When I plug one of these in the system simply reports the drive as being offline and has nothing further to do with it. From what I have read these drives should be compatable. Should this work at all and if so, what might be preventing it?

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  • Core Data - JSON (TouchJSON) on iPhone

    - by Urizen
    I have the following code which seems to go on indefinitely until the app crashes. It seems to happen with the recursion in the datastructureFromManagedObject method. I suspect that this method: 1) looks at the first managed object and follows any relationship property recursively. 2) examines the object at the other end of the relationship found at point 1 and repeats the process. Is it possible that if managed object A has a to-many relationship with object B and that relationship is two-way (i.e an inverse to-one relationship to A from B - e.g. one department has many employees but each employee has only one department) that the following code gets stuck in infinite recursion as it follows the to-one relationship from object B back to object A and so on. If so, can anyone provide a fix for this so that I can get my whole object graph of managed objects converted to JSON. #import "JSONUtils.h" @implementation JSONUtils - (NSDictionary*)dataStructureFromManagedObject:(NSManagedObject *)managedObject { NSDictionary *attributesByName = [[managedObject entity] attributesByName]; NSDictionary *relationshipsByName = [[managedObject entity] relationshipsByName]; //getting the values correspoinding to the attributes collected in attributesByName NSMutableDictionary *valuesDictionary = [[managedObject dictionaryWithValuesForKeys:[attributesByName allKeys]] mutableCopy]; //sets the name for the entity being encoded to JSON [valuesDictionary setObject:[[managedObject entity] name] forKey:@"ManagedObjectName"]; NSLog(@"+++++++++++++++++> before the for loop"); //looks at each relationship for the given managed object for (NSString *relationshipName in [relationshipsByName allKeys]) { NSLog(@"The relationship name = %@",relationshipName); NSRelationshipDescription *description = [relationshipsByName objectForKey:relationshipName]; if (![description isToMany]) { NSLog(@"The relationship is NOT TO MANY!"); [valuesDictionary setObject:[self dataStructureFromManagedObject:[managedObject valueForKey:relationshipName]] forKey:relationshipName]; continue; } NSSet *relationshipObjects = [managedObject valueForKey:relationshipName]; NSMutableArray *relationshipArray = [[NSMutableArray alloc] init]; for (NSManagedObject *relationshipObject in relationshipObjects) { [relationshipArray addObject:[self dataStructureFromManagedObject:relationshipObject]]; } [valuesDictionary setObject:relationshipArray forKey:relationshipName]; } return [valuesDictionary autorelease]; } - (NSArray*)dataStructuresFromManagedObjects:(NSArray*)managedObjects { NSMutableArray *dataArray = [[NSArray alloc] init]; for (NSManagedObject *managedObject in managedObjects) { [dataArray addObject:[self dataStructureFromManagedObject:managedObject]]; } return [dataArray autorelease]; } //method to call for obtaining JSON structure - i.e. public interface to this class - (NSString*)jsonStructureFromManagedObjects:(NSArray*)managedObjects { NSLog(@"-------------> just before running the recursive method"); NSArray *objectsArray = [self dataStructuresFromManagedObjects:managedObjects]; NSLog(@"-------------> just before running the serialiser"); NSString *jsonString = [[CJSONSerializer serializer] serializeArray:objectsArray]; return jsonString; } - (NSManagedObject*)managedObjectFromStructure:(NSDictionary*)structureDictionary withManagedObjectContext:(NSManagedObjectContext*)moc { NSString *objectName = [structureDictionary objectForKey:@"ManagedObjectName"]; NSManagedObject *managedObject = [NSEntityDescription insertNewObjectForEntityForName:objectName inManagedObjectContext:moc]; [managedObject setValuesForKeysWithDictionary:structureDictionary]; for (NSString *relationshipName in [[[managedObject entity] relationshipsByName] allKeys]) { NSRelationshipDescription *description = [[[managedObject entity]relationshipsByName] objectForKey:relationshipName]; if (![description isToMany]) { NSDictionary *childStructureDictionary = [structureDictionary objectForKey:relationshipName]; NSManagedObject *childObject = [self managedObjectFromStructure:childStructureDictionary withManagedObjectContext:moc]; [managedObject setValue:childObject forKey:relationshipName]; continue; } NSMutableSet *relationshipSet = [managedObject mutableSetValueForKey:relationshipName]; NSArray *relationshipArray = [structureDictionary objectForKey:relationshipName]; for (NSDictionary *childStructureDictionary in relationshipArray) { NSManagedObject *childObject = [self managedObjectFromStructure:childStructureDictionary withManagedObjectContext:moc]; [relationshipSet addObject:childObject]; } } return managedObject; } //method to call for obtaining managed objects from JSON structure - i.e. public interface to this class - (NSArray*)managedObjectsFromJSONStructure:(NSString *)json withManagedObjectContext:(NSManagedObjectContext*)moc { NSError *error = nil; NSArray *structureArray = [[CJSONDeserializer deserializer] deserializeAsArray:[json dataUsingEncoding:NSUTF32BigEndianStringEncoding] error:&error]; NSAssert2(error == nil, @"Failed to deserialize\n%@\n%@", [error localizedDescription], json); NSMutableArray *objectArray = [[NSMutableArray alloc] init]; for (NSDictionary *structureDictionary in structureArray) { [objectArray addObject:[self managedObjectFromStructure:structureDictionary withManagedObjectContext:moc]]; } return [objectArray autorelease]; } @end

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  • Double Buffering for Game objects, what's a nice clean generic C++ way?

    - by Gary
    This is in C++. So, I'm starting from scratch writing a game engine for fun and learning from the ground up. One of the ideas I want to implement is to have game object state (a struct) be double-buffered. For instance, I can have subsystems updating the new game object data while a render thread is rendering from the old data by guaranteeing there is a consistent state stored within the game object (the data from last time). After rendering of old and updating of new is finished, I can swap buffers and do it again. Question is, what's a good forward-looking and generic OOP way to expose this to my classes while trying to hide implementation details as much as possible? Would like to know your thoughts and considerations. I was thinking operator overloading could be used, but how do I overload assign for a templated class's member within my buffer class? for instance, I think this is an example of what I want: doublebuffer<Vector3> data; data.x=5; //would write to the member x within the new buffer int a=data.x; //would read from the old buffer's x member data.x+=1; //I guess this shouldn't be allowed If this is possible, I could choose to enable or disable double-buffering structs without changing much code. This is what I was considering: template <class T> class doublebuffer{ T T1; T T2; T * current=T1; T * old=T2; public: doublebuffer(); ~doublebuffer(); void swap(); operator=()?... }; and a game object would be like this: struct MyObjectData{ int x; float afloat; } class MyObject: public Node { doublebuffer<MyObjectData> data; functions... } What I have right now is functions that return pointers to the old and new buffer, and I guess any classes that use them have to be aware of this. Is there a better way?

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  • How to Work Around Limitations in Generic Type Constraints in C#?

    - by Jose
    Okay I'm looking for some input, I'm pretty sure this is not currently supported in .NET 3.5 but here goes. I want to require a generic type passed into my class to have a constructor like this: new(IDictionary<string,object>) so the class would look like this public MyClass<T> where T : new(IDictionary<string,object>) { T CreateObject(IDictionary<string,object> values) { return new T(values); } } But the compiler doesn't support this, it doesn't really know what I'm asking. Some of you might ask, why do you want to do this? Well I'm working on a pet project of an ORM so I get values from the DB and then create the object and load the values. I thought it would be cleaner to allow the object just create itself with the values I give it. As far as I can tell I have two options: 1) Use reflection(which I'm trying to avoid) to grab the PropertyInfo[] array and then use that to load the values. 2) require T to support an interface like so: public interface ILoadValues { void LoadValues(IDictionary values); } and then do this public MyClass<T> where T:new(),ILoadValues { T CreateObject(IDictionary<string,object> values) { T obj = new T(); obj.LoadValues(values); return obj; } } The problem I have with the interface I guess is philosophical, I don't really want to expose a public method for people to load the values. Using the constructor the idea was that if I had an object like this namespace DataSource.Data { public class User { protected internal User(IDictionary<string,object> values) { //Initialize } } } As long as the MyClass<T> was in the same assembly the constructor would be available. I personally think that the Type constraint in my opinion should ask (Do I have access to this constructor? I do, great!) Anyways any input is welcome.

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  • What is a good generic sibling control Javascript communication strategy?

    - by James
    I'm building a webpage that is composed of several controls, and trying to come up with an effective somewhat generic client side sibling control communication model. One of the controls is the menu control. Whenever an item is clicked in here I wanted to expose a custom client side event that other controls can subscribe to, so that I can achieve a loosely coupled sibling control communication model. To that end I've created a simple Javascript event collection class (code below) that acts as like a hub for control event registration and event subscription. This code certainly gets the job done, but my question is is there a better more elegant way to do this in terms of best practices or tools, or is this just a fools errand? /// Event collection object - acts as the hub for control communication. function ClientEventCollection() { this.ClientEvents = {}; this.RegisterEvent = _RegisterEvent; this.AttachToEvent = _AttachToEvent; this.FireEvent = _FireEvent; function _RegisterEvent(eventKey) { if (!this.ClientEvents[eventKey]) this.ClientEvents[eventKey] = []; } function _AttachToEvent(eventKey, handlerFunc) { if (this.ClientEvents[eventKey]) this.ClientEvents[eventKey][this.ClientEvents[eventKey].length] = handlerFunc; } function _FireEvent(eventKey, triggerId, contextData ) { if (this.ClientEvents[eventKey]) { for (var i = 0; i < this.ClientEvents[eventKey].length; i++) { var fn = this.ClientEvents[eventKey][i]; if (fn) fn(triggerId, contextData); } } } } // load new collection instance. var myClientEvents = new bsdClientEventCollection(); // register events specific to the control that owns it, this will be emitted by each respective control. myClientEvents.RegisterEvent("menu-item-clicked"); Here is the part where this code above is consumed by source and subscriber controls. // menu control $(document).ready(function() { $(".menu > a").click( function(event) { //event.preventDefault(); myClientEvents.FireEvent("menu-item-clicked", $(this).attr("id"), null); }); }); <div style="float: left;" class="menu"> <a id="1" href="#">Menu Item1</a><br /> <a id="2" href="#">Menu Item2</a><br /> <a id="3" href="#">Menu Item3</a><br /> <a id="4" href="#">Menu Item4</a><br /> </div> // event subscriber control $(document).ready(function() { myClientEvents.AttachToEvent("menu-item-clicked", menuItemChanged); myClientEvents.AttachToEvent("menu-item-clicked", menuItemChanged2); myClientEvents.AttachToEvent("menu-item-clicked", menuItemChanged3); }); function menuItemChanged(id, contextData) { alert('menuItemChanged ' + id); } function menuItemChanged2(id, contextData) { alert('menuItemChanged2 ' + id); } function menuItemChanged3(id, contextData) { alert('menuItemChanged3 ' + id); }

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  • C problem, left of '->' must point to class/struct/union/generic type ??

    - by Patrick
    Hello! Trying to understand why this doesn't work. I keep getting the following errors: left of '-nextNode' must point to class/struct/union/generic type (Also all the lines with a - in the function new_math_struct) Header file #ifndef MSTRUCT_H #define MSTRUCT_H #define PLUS 0 #define MINUS 1 #define DIVIDE 2 #define MULTIPLY 3 #define NUMBER 4 typedef struct math_struct { int type_of_value; int value; int sum; int is_used; struct math_struct* nextNode; } ; typedef struct math_struct* math_struct_ptr; #endif C file int get_input(math_struct_ptr* startNode) { /* character, input by the user */ char input_ch; char* input_ptr; math_struct_ptr* ptr; math_struct_ptr* previousNode; input_ptr = &input_ch; previousNode = startNode; /* as long as input is not ok */ while (1) { input_ch = get_input_character(); if (input_ch == ',') // Carrage return return 1; else if (input_ch == '.') // Illegal character return 0; if (input_ch == '+') ptr = new_math_struct(PLUS, 0); else if (input_ch == '-') ptr = new_math_struct(MINUS, 0); else if (input_ch == '/') ptr = new_math_struct(DIVIDE, 0); else if (input_ch == '*') ptr = new_math_struct(MULTIPLY, 0); else ptr = new_math_struct(NUMBER, atoi(input_ptr)); if (startNode == NULL) { startNode = previousNode = ptr; } else { previousNode->nextNode = ptr; previousNode = ptr; } } return 0; } math_struct_ptr* new_math_struct(int symbol, int value) { math_struct_ptr* ptr; ptr = (math_struct_ptr*)malloc(sizeof(math_struct_ptr)); ptr->type_of_value = symbol; ptr->value = value; ptr->sum = 0; ptr->is_used = 0; return ptr; } char get_input_character() { /* character, input by the user */ char input_ch; /* get the character */ scanf("%c", &input_ch); if (input_ch == '+' || input_ch == '-' || input_ch == '*' || input_ch == '/' || input_ch == ')') return input_ch; // A special character else if (input_ch == '\n') return ','; // A carrage return else if (input_ch < '0' || input_ch > '9') return '.'; // Not a number else return input_ch; // Number } The header for the C file just contains a reference to the struct header and the definitions of the functions. Language C.

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  • Virtualbox on Ubuntu 12.04 and 3.5 kernel

    - by kas
    I have installed the 3.5 kernel under Ubuntu 12.04. When I install virtualbox I recieve the following error. Setting up virtualbox (4.1.12-dfsg-2ubuntu0.2) ... * Stopping VirtualBox kernel modules [ OK ] * Starting VirtualBox kernel modules * No suitable module for running kernel found [fail] invoke-rc.d: initscript virtualbox, action "restart" failed. Processing triggers for python-central ... Setting up virtualbox-dkms (4.1.12-dfsg-2ubuntu0.2) ... Loading new virtualbox-4.1.12 DKMS files... First Installation: checking all kernels... Building only for 3.5.0-18-generic Building initial module for 3.5.0-18-generic Error! Bad return status for module build on kernel: 3.5.0-18-generic (x86_64) Consult /var/lib/dkms/virtualbox/4.1.12/build/make.log for more information. * Stopping VirtualBox kernel modules [ OK ] * Starting VirtualBox kernel modules * No suitable module for running kernel found [fail] invoke-rc.d: initscript virtualbox, action "restart" failed. Setting up virtualbox-qt (4.1.12-dfsg-2ubuntu0.2) ... Does anyone know how I might be able to resolve this? Edit -- Here is the make.log DKMS make.log for virtualbox-4.1.12 for kernel 3.5.0-18-generic (x86_64) Mon Nov 19 12:12:23 EST 2012 make: Entering directory `/usr/src/linux-headers-3.5.0-18-generic' LD /var/lib/dkms/virtualbox/4.1.12/build/built-in.o LD /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/built-in.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/linux/SUPDrv-linux.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/SUPDrv.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/SUPDrvSem.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/alloc-r0drv.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/initterm-r0drv.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/memobj-r0drv.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/mpnotification-r0drv.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/powernotification-r0drv.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/linux/assert-r0drv-linux.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/linux/alloc-r0drv-linux.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/linux/initterm-r0drv-linux.o CC [M] /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/linux/memobj-r0drv-linux.o /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/linux/memobj-r0drv-linux.c: In function ‘rtR0MemObjLinuxDoMmap’: /var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/linux/memobj-r0drv-linux.c:1150:9: error: implicit declaration of function ‘do_mmap’ [-Werror=implicit-function-declaration] cc1: some warnings being treated as errors make[2]: *** [/var/lib/dkms/virtualbox/4.1.12/build/vboxdrv/r0drv/linux/memobj-r0drv-linux.o] Error 1 make[1]: *** [/var/lib/dkms/virtualbox/4.1.12/build/vboxdrv] Error 2 make: *** [_module_/var/lib/dkms/virtualbox/4.1.12/build] Error 2 make: Leaving directory `/usr/src/linux-headers-3.5.0-18-generic'

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  • I have Ubuntu alongside Windows Vista and I cannot reboot Windows Vista

    - by railguage48
    I cannot get into Windows Vista .... I was working in Vista and then I restarted booted up Ubuntu and when I finished in Ubuntu I restarted this time in Vista and all I get is the microsoft box with the vertical stripes running interminably. I ran sudo update-grub this is the result of that command: generating grub.cfg found linux image: /boot/vmlinuz-3.2.0-24-generic found initrd image: /boot/iniytd.img-3.2.0-24-generic found linux image: /boot/vmlinuz-3.0.0-19-generic found linitrd image: /boot/initrd.img-3.0.0-19-generic found windows recovery environment (loader) on /dev/sda1 skipping windows recovery environment (loader) on Wubi system found windows vista (loader) on /dev/sda2 skipping windows vista (loader) on wubi system I do have a backup of my Windows environment on an external hard drive and I can get to it through ubuntu but I am not sure if I can restore Windows Vista from Ubuntu or even if I need to. Thanks for any help.

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