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  • Simple end-to-end load and bottleneck monitoring for DB-based web sites

    - by T.J. Crowder
    What tools do you use / would you recommend for monitoring a Linux-based, DB-based website's servers for bottlenecks and load? The obvious goal being to know when growth has gotten to the point where it's necessary to scale up (or out) one or more of the bits and pieces because the current system won't be managing the load if an observed trend continues. I'm looking for general recommendations based on standard Linux load metrics, disk I/O metrics, network I/O metrics, etc., but if specifics are helpful: It'll be Tomcat6 using APR (possibly with a Varnish or similar caching and balancing front-end), MySQL, and either Ubuntu 8.04 LTS or 10.04 LTS depending on timing. I know about top, vmstat, iostat, bwmon and the like that collect and parse info from the /proc file system (et. al.); and obviously MySQL provides a lot of queriable performance information. I could use those directly, probably automating periodic monitoring logs with scripts and such. But I have a suspicion that I'd be reinventing a wheel... For example, Hyperic HQ seems to be along the lines of what I'm looking for. Others? Meta: I tend to think of "recommendation" questions as needing to be CW because there's no one right answer, but I see a lot of these here that aren't CWs, so I haven't marked it as one. I'll happily do so if enough people think I should.

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  • Network Load Balancing, intermittent port problem

    - by Jimmy Chandra
    Trying to troubleshoot an intermittent problem. I think it might be related to an NLB issue. We are using Windows Network Load Balancing to balance load for our multiserver SharePoint front ends. Say... Web Front End 1 IP is 192.168.1.100 and Web Front End 2 IP is 192.168.1.101, the NLB is setup to load balance both WFE servers on any incoming traffic to the IP 192.168.1.200. Sometimes we got an intermittent issue where when we try to access the SharePoint site using 192.168.1.200:8080 (say the site is set up to run on port 8080) from a remote client, it will display page not found. Pinging the 192.168.1.200 will give responses, but when trying to telnet to 192.168.1.200:8080 it just won't connect. However, browsing the SharePoint site directly on individual WFE (192.168.1.100 and 192.168.1.101) show no problem whatsoever. My guess also (we didn't get a chance to try it yet, but I think it should work), if I try connecting remotely to individual server, it will respond just fine. But any attempt on trying to connect using the virtual IP (192.168.1.200) will fail miserably. Funny thing is, after a while it will return back to normal. Anyone had similar experience with this type of problem while implementing NLB before? We are doing this in a virtual environment.

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  • How many reverse proxies (nginx, haproxy) is too many?

    - by Alysum
    I'm setting up a HA (high availability) cluster using nginx, haproxy & apache. I've been reading great things about nginx and haproxy. People tend to choose one or the other but I like both. Haproxy is more flexible for load balancing than nginx's simple round robin (even with the upstream-fair patch). But I'd like to keep nginx for redirecting non-https to https among other things right at the point of entry to the cluster. On the other hand, nginx is a lot faster for serving static contents and would reduce the load on the powerful apache which loves to eat a lot of RAM! Here is my planned setup: Load balancer: nginx listens on port 80/443 and proxy_forwards to haproxy on 8080 on the same server to load balance between the multiple nodes. Nodes: nginx on the node listens to requests coming from haproxy on 8080, if the content is static, serve it. But if it's a backend script (in my case PHP), proxy forward to apache2 on the same node server listenning on a different port number. Technically this setup works but my concerns are whether having the requests going through several proxies is going to slow down requests? Most of the requests will be PHP requests as the backends are services (which means groing from nginx - haproxy - nginx - apache). Thoughts? Cheers

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  • Network Load Balancing, intermittent port problem on Windows Server 2008

    - by Jimmy Chandra
    Trying to troubleshoot an intermittent problem on a Windows Server 2008 NLB. I think it might be related to an NLB issue. We are using Windows Network Load Balancing to balance load for our multiserver SharePoint front ends. Say... Web Front End 1 IP is 192.168.1.100 and Web Front End 2 IP is 192.168.1.101, the NLB is setup to load balance both WFE servers on any incoming traffic to the IP 192.168.1.200. Sometimes we got an intermittent issue where when we try to access the SharePoint site using 192.168.1.200:8080 (say the site is set up to run on port 8080) from a remote client, it will display page not found. Pinging the 192.168.1.200 will give responses, but when trying to telnet to 192.168.1.200:8080 it just won't connect. However, browsing the SharePoint site directly on individual WFE (192.168.1.100 and 192.168.1.101) show no problem whatsoever. My guess also (we didn't get a chance to try it yet, but I think it should work), if I try connecting remotely to individual server, it will respond just fine. But any attempt on trying to connect using the virtual IP (192.168.1.200) will fail miserably. Funny thing is, after a while it will return back to normal. Anyone had similar experience with this type of problem while implementing NLB before? We are doing this in a virtual environment.

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  • What system of administrative e-mail addresses does your organization use?

    - by Draco Flangetastic
    I'm getting ready to request a new batch of administrative e-mail addresses to replace an outdated hierarchy within my organization. I have the opportunity of choosing new aliases for 24/7 alert recipients, monitoring recipients, all team members, etc. What does your org use for these purposes? Groups in my org use things like: org-dept@, org-dept-all@, org-dept-alert@, org-dept-monitoring@, org-dept-status@. TIA!!!!!111

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  • Configure tomcat behind loadbalancer to respond on HTTP and HTTPS

    - by user253530
    I have 2 tomcat machines behind a load balancer on Amazon EC2. Until now The load balancer was configured to respond only on https. So in order to access our services you would go to https://url. Tomcat was configured to listen on 8080 but the connector had additional params that would tell tomcat that it is behind a proxy and that it should respond on HTTPS 443. The connector looks like this: <Connector scheme="https" secure="true" proxyPort="443" proxyHost="my.domain.name" port="8080" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" useBodyEncodingForURI="true" URIEncoding="UTF-8" /> What i would like to do is to open port 80 on the load balancer and basically allow traffic on HTTP and HTTPS. I've configured the load balancer to redirect all HTTP traffic to the tomcat machines on port 8088. I was thinking that i could define a new connector so that all HTTPS traffic goes to 8080 and HTTP to 8088. Unfortunately i did not succeed. Here is my connector <Connector port="8088" protocol="HTTP/1.1" connectionTimeout="20000" redirectPort="8443" useBodyEncodingForURI="true" URIEncoding="UTF-8" /> Am I missing something? Thanks

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  • Difference between “system-on-chip” and “CPU”

    - by Tim
    Very confused, in some websites, they have this line: iPhone 5s CPU: Apple A7 other websites saying that: iPhone 5s System-on-chip: Apple 7 CPU: 1.3 GHz 64bit dual core other sources saying that iPhone 5s System-on-chip: Apple 7 CPU: 1.3 GHz 64bit dual core Apple 7 In Wikipedia, it said: The Apple A7 is a 64-bit system on a chip (SoC) designed by Apple Inc. It first appeared in the iPhone 5S, which was introduced on September 10, 2013. Apple states that it is up to twice as fast and has up to twice the graphics power compared to its predecessor, the Apple A6. While not the first 64-bit ARM CPU, it is the first to ship in a consumer smartphone or tablet computer. There are 2 sentences: The Apple A7 is a 64-bit system on a chip (SoC) and While not the first 64-bit ARM CPU Wikipedia also said “The A7 features an Apple-designed 64-bit 1.3–1.4 GHz ARMv8-A dual-core CPU, called Cyclone”. So System on chip is also CPU? very confused

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  • Server load increases by lot of httpd request with same PID

    - by user3740955
    I can see that my server load increases to more than 200-300 range. Before 1 week the maximum load was around 20-25. In top and ps -ef i can see a lot of httpd threads and the PPID of most of the httpd request are of the same PID. When i verified this the parent process ID is of root. Please let me know how i can reduce the server load. I have searched a lot for this but not able to find out a proper solution for this. Please let me know. Please see below a part of the top output. apache 29698 2062 1 16:54 ? 00:00:00 /usr/sbin/httpd apache 29700 2062 3 16:54 ? 00:00:00 /usr/sbin/httpd apache 29701 2062 10 16:54 ? 00:00:02 /usr/sbin/httpd apache 29702 2062 0 16:54 ? 00:00:00 /usr/sbin/httpd apache 29703 2062 1 16:54 ? 00:00:00 /usr/sbin/httpd apache 29705 2062 0 16:54 ? 00:00:00 /usr/sbin/httpd apache 29706 2062 3 16:54 ? 00:00:00 /usr/sbin/httpd apache 29707 2062 0 16:54 ? 00:00:00 /usr/sbin/httpd apache 29708 2062 1 16:54 ? 00:00:00 /usr/sbin/httpd apache 29709 2062 0 16:54 ? 00:00:00 /usr/sbin/httpd apache 29710 2062 0 16:54 ? 00:00:00 /usr/sbin/httpd apache 29711 2062 0 16:54 ? 00:00:00 /usr/sbin/httpd apache 29712 2062 0 16:54 ? 00:00:00 /usr/sbin/httpd Server version: Apache/2.2.3

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  • How do I stop Mac OS X Snow Leopard from losing the keyboard shortcuts I create in System Preferences?

    - by Philip
    I can't explain it. In OS X 10.6.6 (but also in previous versions; nothing to do w/ latest update), I create some keyboard shortcuts both for individual applications and for "all applications." I use them for a while. Later, sometimes after restart sometimes not, they're gone. Where'd they go?!?! (More importantly, how do I make them stop disappearing? Less ideal solution: how do I back them up and quickly restore them?) Thanks!

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  • Some pages begin to load and stop on Chrome

    - by corsiKa
    I'm using Chrome (Version 22.0.1229.94). About 20% of pages simply stop loading after a second or two. Sometimes, I'm able to click an early link after a second or third reload. If I attempt to close the page, it continues to hang for a few (10-30) additional seconds, then closes. However, if I switch to other tabs, it works just fine. If I don't change tabs and wait long enough, it says that there's something on the page that's taking too long to run and offers to let me kill it. Only a select number of sites fail to load, and they do so consistently. None of the stackexchange sites or google fail, but others like realclearpolitics and wowwiki do. I visit those sites every day, and this is the first time it has failed like this. If it were just one site, I would say someone messed something up in their deployment. But it seems incredibly peculiar that suddenly, half a dozen popular sites all mysteriously have the same symptoms. If I attempt to load the pages in Firefox or IE9, they load just fine. Nothing new has been installed, regarding Chrome or otherwise. Antivirus reports no abnormalities. System is regularly patched. Restarting both chrome and the computer have had no effect.

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  • Software update shows "P??roblem with the system installer tool" error in OS X Lion

    - by Elnaz Shahmehr
    I can't update my system. Does anyone know what the problem is? sudo softwareupdate -i -a Password: Software Update Tool Copyright 2002-2010 Apple Downloading Digital Camera Raw Compatibility Update Waiting to install Digital Camera Raw Compatibility Update Downloading Java for OS X 2012-002 Verifying Java for OS X 2012-002 Waiting to install Java for OS X 2012-002 Downloading iTunes Waiting to install iTunes Downloading Safari Verifying Safari Waiting to install Safari Checking packages… Installing Waiting for other installations to complete… Validating packages… Writing files… Package failed: There was a problem with the system installer tool. Package failed: There was a problem with the system installer tool. Package failed: There was a problem with the system installer tool. Package failed: There was a problem with the system installer tool. Done.

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  • SQL SERVER – Find Max Worker Count using DMV – 32 Bit and 64 Bit

    - by pinaldave
    During several recent training courses, I found it very interesting that Worker Thread is not quite known to everyone despite the fact that it is a very important feature. At some point in the discussion, one of the attendees mentioned that we can double the Worker Thread if we double the CPU (add the same number of CPU that we have on current system). The same discussion has triggered this quick article. Here is the DMV which can be used to find out Max Worker Count SELECT max_workers_count FROM sys.dm_os_sys_info Let us run the above query on my system and find the results. As my system is 32 bit and I have two CPU, the Max Worker Count is displayed as 512. To address the previous discussion, adding more CPU does not necessarily double the Worker Count. In fact, the logic behind this simple principle is as follows: For x86 (32-bit) upto 4 logical processors  max worker threads = 256 For x86 (32-bit) more than 4 logical processors  max worker threads = 256 + ((# Procs – 4) * 8) For x64 (64-bit) upto 4 logical processors  max worker threads = 512 For x64 (64-bit) more than 4 logical processors  max worker threads = 512+ ((# Procs – 4) * 8) In addition to this, you can configure the Max Worker Thread by using SSMS. Go to Server Node >> Right Click and Select Property >> Select Process and modify setting under Worker Threads. According to Book On Line, the default Worker Thread settings are appropriate for most of the systems. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL System Table, SQL Tips and Tricks, T SQL, Technology Tagged: SQL DMV

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  • Proper way to remove an active / inactive LVM snapshot

    - by user2622247
    I have created a sample ruby script file for removing extra LVM snapshots from the system. For removing LVM snapshot, we are using lvremove command. This command is working fine and we can remove snapshots from the system. # sudo lvremove /dev/ops/dbbackup lvremove -- do you really want to remove "/dev/ops/dbbackup"? [y/n]: y Sometimes while removing snapshots we are getting following errors. Unable to deactivate open rootfs_12.10_20140812_00-cow (252:8) Failed to resume rootfs_12.10_20140812_00. libdevmapper exiting with 7 device(s) still suspended. The system gets frozen. We cannot fire any command or can not perform any action on it. After restarting the system, it is functioning fine. We can perform all the operations even we can delete that snapshot also. I searched about it I found these threads https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=659762 and https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=674682 Solution from this thread is after getting the error but I have to avoid this type of error. I have a question, Is there any better way removing LVM snapshots? So that we can avoid this type of error. If anyone needs more info feel free to ask me.

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  • Hibernate : load and

    - by Albert Kam
    According to the tutorial : http://jpa.ezhibernate.com/Javacode/learn.jsp?tutorial=27hibernateloadvshibernateget, If you initialize a JavaBean instance with a load method call, you can only access the properties of that JavaBean, for the first time, within the transactional context in which it was initialized. If you try to access the various properties of the JavaBean after the transaction that loaded it has been committed, you'll get an exception, a LazyInitializationException, as Hibernate no longer has a valid transactional context to use to hit the database. But with my experiment, using hibernate 3.6, and postgres 9, it doesnt throw any exception at all. Am i missing something ? Here's my code : import org.hibernate.Session; public class AppLoadingEntities { /** * @param args */ public static void main(String[] args) { HibernateUtil.beginTransaction(); Session session = HibernateUtil.getSession(); EntityUser userFromGet = get(session); EntityUser userFromLoad = load(session); // finish the transaction session.getTransaction().commit(); // try fetching field value from entity bean that is fetched via get outside transaction, and it'll be okay System.out.println("userFromGet.getId() : " + userFromGet.getId()); System.out.println("userFromGet.getName() : " + userFromGet.getName()); // fetching field from entity bean that is fetched via load outside transaction, and it'll be errornous // NOTE : but after testing, load seems to be okay, what gives ? ask forums try { System.out.println("userFromLoad.getId() : " + userFromLoad.getId()); System.out.println("userFromLoad.getName() : " + userFromLoad.getName()); } catch(Exception e) { System.out.println("error while fetching entity that is fetched from load : " + e.getMessage()); } } private static EntityUser load(Session session) { EntityUser user = (EntityUser) session.load(EntityUser.class, 1l); System.out.println("user fetched with 'load' inside transaction : " + user); return user; } private static EntityUser get(Session session) { // safe to set it to 1, coz the table got recreated at every run of this app EntityUser user = (EntityUser) session.get(EntityUser.class, 1l); System.out.println("user fetched with 'get' : " + user); return user; } } And here's the output : 88 [main] INFO org.hibernate.annotations.common.Version - Hibernate Commons Annotations 3.2.0.Final 93 [main] INFO org.hibernate.cfg.Environment - Hibernate 3.6.0.Final 94 [main] INFO org.hibernate.cfg.Environment - hibernate.properties not found 96 [main] INFO org.hibernate.cfg.Environment - Bytecode provider name : javassist 98 [main] INFO org.hibernate.cfg.Environment - using JDK 1.4 java.sql.Timestamp handling 139 [main] INFO org.hibernate.cfg.Configuration - configuring from resource: /hibernate.cfg.xml 139 [main] INFO org.hibernate.cfg.Configuration - Configuration resource: /hibernate.cfg.xml 172 [main] WARN org.hibernate.util.DTDEntityResolver - recognized obsolete hibernate namespace http://hibernate.sourceforge.net/. Use namespace http://www.hibernate.org/dtd/ instead. Refer to Hibernate 3.6 Migration Guide! 191 [main] INFO org.hibernate.cfg.Configuration - Configured SessionFactory: null 237 [main] INFO org.hibernate.cfg.AnnotationBinder - Binding entity from annotated class: EntityUser 263 [main] INFO org.hibernate.cfg.annotations.EntityBinder - Bind entity EntityUser on table MstUser 293 [main] INFO org.hibernate.cfg.Configuration - Hibernate Validator not found: ignoring 296 [main] INFO org.hibernate.cfg.search.HibernateSearchEventListenerRegister - Unable to find org.hibernate.search.event.FullTextIndexEventListener on the classpath. Hibernate Search is not enabled. 300 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - Using Hibernate built-in connection pool (not for production use!) 300 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - Hibernate connection pool size: 20 300 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - autocommit mode: false 309 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - using driver: org.postgresql.Driver at URL: jdbc:postgresql://localhost:5432/hibernate 309 [main] INFO org.hibernate.connection.DriverManagerConnectionProvider - connection properties: {user=sofco, password=****} 354 [main] INFO org.hibernate.cfg.SettingsFactory - Database -> name : PostgreSQL version : 9.0.1 major : 9 minor : 0 354 [main] INFO org.hibernate.cfg.SettingsFactory - Driver -> name : PostgreSQL Native Driver version : PostgreSQL 9.0 JDBC4 (build 801) major : 9 minor : 0 372 [main] INFO org.hibernate.dialect.Dialect - Using dialect: org.hibernate.dialect.PostgreSQLDialect 382 [main] INFO org.hibernate.engine.jdbc.JdbcSupportLoader - Disabling contextual LOB creation as createClob() method threw error : java.lang.reflect.InvocationTargetException 383 [main] INFO org.hibernate.transaction.TransactionFactoryFactory - Transaction strategy: org.hibernate.transaction.JDBCTransactionFactory 384 [main] INFO org.hibernate.transaction.TransactionManagerLookupFactory - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended) 384 [main] INFO org.hibernate.cfg.SettingsFactory - Automatic flush during beforeCompletion(): disabled 384 [main] INFO org.hibernate.cfg.SettingsFactory - Automatic session close at end of transaction: disabled 384 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC batch size: 15 384 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC batch updates for versioned data: disabled 384 [main] INFO org.hibernate.cfg.SettingsFactory - Scrollable result sets: enabled 384 [main] INFO org.hibernate.cfg.SettingsFactory - JDBC3 getGeneratedKeys(): enabled 384 [main] INFO org.hibernate.cfg.SettingsFactory - Connection release mode: auto 385 [main] INFO org.hibernate.cfg.SettingsFactory - Default batch fetch size: 1 385 [main] INFO org.hibernate.cfg.SettingsFactory - Generate SQL with comments: disabled 385 [main] INFO org.hibernate.cfg.SettingsFactory - Order SQL updates by primary key: disabled 385 [main] INFO org.hibernate.cfg.SettingsFactory - Order SQL inserts for batching: disabled 385 [main] INFO org.hibernate.cfg.SettingsFactory - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory 385 [main] INFO org.hibernate.hql.ast.ASTQueryTranslatorFactory - Using ASTQueryTranslatorFactory 385 [main] INFO org.hibernate.cfg.SettingsFactory - Query language substitutions: {} 385 [main] INFO org.hibernate.cfg.SettingsFactory - JPA-QL strict compliance: disabled 385 [main] INFO org.hibernate.cfg.SettingsFactory - Second-level cache: enabled 385 [main] INFO org.hibernate.cfg.SettingsFactory - Query cache: disabled 385 [main] INFO org.hibernate.cfg.SettingsFactory - Cache region factory : org.hibernate.cache.impl.NoCachingRegionFactory 386 [main] INFO org.hibernate.cfg.SettingsFactory - Optimize cache for minimal puts: disabled 386 [main] INFO org.hibernate.cfg.SettingsFactory - Structured second-level cache entries: disabled 388 [main] INFO org.hibernate.cfg.SettingsFactory - Echoing all SQL to stdout 389 [main] INFO org.hibernate.cfg.SettingsFactory - Statistics: disabled 389 [main] INFO org.hibernate.cfg.SettingsFactory - Deleted entity synthetic identifier rollback: disabled 389 [main] INFO org.hibernate.cfg.SettingsFactory - Default entity-mode: pojo 389 [main] INFO org.hibernate.cfg.SettingsFactory - Named query checking : enabled 389 [main] INFO org.hibernate.cfg.SettingsFactory - Check Nullability in Core (should be disabled when Bean Validation is on): enabled 402 [main] INFO org.hibernate.impl.SessionFactoryImpl - building session factory 549 [main] INFO org.hibernate.impl.SessionFactoryObjectFactory - Not binding factory to JNDI, no JNDI name configured Hibernate: select entityuser0_.id as id0_0_, entityuser0_.name as name0_0_, entityuser0_.password as password0_0_ from MstUser entityuser0_ where entityuser0_.id=? user fetched with 'get' : 1:Albert Kam xzy:abc user fetched with 'load' inside transaction : 1:Albert Kam xzy:abc userFromGet.getId() : 1 userFromGet.getName() : Albert Kam xzy userFromLoad.getId() : 1 userFromLoad.getName() : Albert Kam xzy

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  • Where can I find information on the Get, Set and Address methods for multidimensional System.Array i

    - by Rob Smallshire
    System.Array serves as the base class for all arrays in the Common Language Runtime (CLR). According to this article, For each concrete array type, [the] runtime adds three special methods: Get/Set/Address. and indeed if I disassemble this C# code, int[,] x = new int[1024,1024]; x[0,0] = 1; x[1,1] = 2; x[2,2] = 3; Console.WriteLine(x[0,0]); Console.WriteLine(x[1,1]); Console.WriteLine(x[2,2]); into CIL I get, IL_0000: ldc.i4 0x400 IL_0005: ldc.i4 0x400 IL_000a: newobj instance void int32[0...,0...]::.ctor(int32, int32) IL_000f: stloc.0 IL_0010: ldloc.0 IL_0011: ldc.i4.0 IL_0012: ldc.i4.0 IL_0013: ldc.i4.1 IL_0014: call instance void int32[0...,0...]::Set(int32, int32, int32) IL_0019: ldloc.0 IL_001a: ldc.i4.1 IL_001b: ldc.i4.1 IL_001c: ldc.i4.2 IL_001d: call instance void int32[0...,0...]::Set(int32, int32, int32) IL_0022: ldloc.0 IL_0023: ldc.i4.2 IL_0024: ldc.i4.2 IL_0025: ldc.i4.3 IL_0026: call instance void int32[0...,0...]::Set(int32, int32, int32) IL_002b: ldloc.0 IL_002c: ldc.i4.0 IL_002d: ldc.i4.0 IL_002e: call instance int32 int32[0...,0...]::Get(int32, int32) IL_0033: call void [mscorlib]System.Console::WriteLine(int32) IL_0038: ldloc.0 IL_0039: ldc.i4.1 IL_003a: ldc.i4.1 IL_003b: call instance int32 int32[0...,0...]::Get(int32, int32) IL_0040: call void [mscorlib]System.Console::WriteLine(int32) IL_0045: ldloc.0 IL_0046: ldc.i4.2 IL_0047: ldc.i4.2 IL_0048: call instance int32 int32[0...,0...]::Get(int32, int32) IL_004d: call void [mscorlib]System.Console::WriteLine(int32) where the calls to the aforementioned Get and Set methods can be clearly seen. It seems the arity of these methods is related to the dimensionality of the array, which is presumably why they are created by the runtime and are not pre-declared. I couldn't locate any information about these methods on MSDN and their simple names makes them resistant to Googling. I'm writing a compiler for a language which supports multidimensional arrays, so I'd like to find some official documentation about these methods, under what conditions I can expect them to exist and what I can expect their signatures to be. In particular, I'd like to know whether its possible to get a MethodInfo object for Get or Set for use with Reflection.Emit without having to create an instance of the array with correct type and dimensionality on which to reflect, as is done in the linked example.

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  • Designing an email system to guarantee delivery

    - by GlenH7
    We are looking to expand our use of email for notification purposes. We understand it will generate more inbox volume, but we are being selective about which events we fire notification on in order to keep the signal-to-noise ratio high. The big question we are struggling with is designing a system that guarantees that the email was delivered. If an email isn't delivered, we will consider that an exception event that needs to be investigated. In reality, I say almost guarantees because there aren't any true guarantees with email. We're just looking for a practical solution to making sure the email got there and experiences others have had with the various approaches to guaranteeing delivery. For the TL;DR crowd - how do we go about designing a system to guarantee delivery of emails? What techniques should we consider so we know the emails were delivered? Our biggest area of concern is what techniques to use so that we know when a message is sent out that it either lands in an inbox or it failed and we need to do something else. Additional requirements: We're not at the stage of including an escalation response, but we'll want that in the future or so we think. Most notifications will be internal to our enterprise, but we will have some notifications being sent to external clients. Some of our application is in a hosted environment. We haven't determined if those servers can access our corporate email servers for relaying or if they'll be acting as their own mail servers. Base design / modules (at the moment): A module to assign tracking identification A module to send out emails A module to receive delivery notification (perhaps this is the same as the email module) A module that checks sent messages against delivery notification and alerts on undelivered email. Some references: Atwood: Send some email Email Tracking Some approaches: Request a response (aka read-receipt or Message Disposition Notification). Seems prone to failure since we have cross-compatibility issues due to differing mail servers and software. Return receipt (aka Delivery Status Notification). Not sure if all mail servers honor this request or not Require an action and therefore prove reply. Seems burdensome to force the recipients to perform an additional task not related to resolving the issue. And no, we haven't come up with a way of linking getting the issue fixed to whether or not the email was received. Force a click-through / Other site sign-in. Similar to requiring some sort of action, this seems like an additional burden and will annoy the users. On the other hand, it seems the most likely to guarantee someone received the notification. Hidden image tracking. Not all email providers automatically load the image, and how would we associate the image(s) with the email tracking ID? Outsource delivery. This gets us out of the email business, but goes back to how to guarantee the out-sourcer's receipt and subsequent delivery to the end recipient. As a related concern, there will be an n:n relationship between issue notification and recipients. The 1 issue : n recipients subset isn't as much of a concern although if we had a delivery failure we would want to investigate and fix the core issue. Of bigger concern is n issues : 1 recipient, and we're specifically concerned in making sure that all n issues were received by the recipient. How does forum software or issue tracking software handle this requirement? If a tracking identifier is used, Where is it placed in the email? In the Subject, or the Body?

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  • Designing An ACL Based Permission System

    - by ryanzec
    I am trying to create a permissions system where everything is going to be stored in MySQL (or some database) and pulled using PHP for a project management system I am building.  I am right now trying to do it is an ACL kind of way.  There are a number key features I want to be able to support: 1.  Being able to assign permissions without being tied to a specific object. The reason for this is that I want to be able to selectively show/hide elements of the UI based on permissions at a point where I am not directly looking at a domain object instance.  For instance, a button to create a new project should only should only be shown to users that have the pm.project.create permission but obviously you can assign a create permission to an domain object instance (as it is already created). 2.  Not have to assign permissions for every single object. Obviously creating permissions entries for every single object (projects, tickets, comments, etc…) would become a nightmare to maintain so I want to have some level of permission inheritance. *3.  Be able to filter queries based on permissions. This would be a really nice to have but I am not sure if it is possible.  What I mean by this is say I have a page that list all projects.  I want the query that pulls all projects to incorporate the ACL so that it would not show projects that the current user does not have pm.project.read access to.  This would have to be incorporated into the main query as if it is a process that is done after that main query (which I know I could do) certain features like pagination become much more difficult. Right now this is my basic design for the tables: AclEntities id - the primary key key - the unique identifier for the domain object (usually the primary key of that object) parentId - the parent of the domain object (like the project object if this was a ticket object) aclDomainObjectId - metadata about the domain object AclDomainObjects id - primary key title - simple string to unique identify the domain object(ie. project, ticket, comment, etc…) fullyQualifiedClassName - the fully qualified class name for use in code (I am using namespaces) There would also be tables mapping AclEntities to Users and UserGroups. I also have this interface that all acl entity based object have to implement: IAclEntity getAclKey() - to the the unique key for this specific instance of the acl domain object (generally return the primary key or a concatenated string of a composite primary key) getAclTitle() - to get the unique title for the domain object (generally just returning a static string) getAclDisplayString() - get the string that represents this entity (generally one or more field on the object) getAclParentEntity() - get the parent acl entity object (or null if no parent) getAclEntity() - get the acl enitty object for this instance of the domain object (or null if one has not been created yet) hasPermission($permissionString, $user = null) - whether or not the user has the permission for this instance of the domain object static getFromAclEntityId($aclEntityId) - get a specific instance of the domain object from an acl entity id. Do any of these features I am looking for seems hard to support or are just way off base? Am I missing or not taking in account anything in my implementation? Is performance something I should keep in mind?

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  • Help understand GLSL directional light on iOS (left handed coord system)

    - by Robse
    I now have changed from GLKBaseEffect to a own shader implementation. I have a shader management, which compiles and applies a shader to the right time and does some shader setup like lights. Please have a look at my vertex shader code. Now, light direction should be provided in eye space, but I think there is something I don't get right. After I setup my view with camera I save a lightMatrix to transform the light from global space to eye space. My modelview and projection setup: - (void)setupViewWithWidth:(int)width height:(int)height camera:(N3DCamera *)aCamera { aCamera.aspect = (float)width / (float)height; float aspect = aCamera.aspect; float far = aCamera.far; float near = aCamera.near; float vFOV = aCamera.fieldOfView; float top = near * tanf(M_PI * vFOV / 360.0f); float bottom = -top; float right = aspect * top; float left = -right; // projection GLKMatrixStackLoadMatrix4(projectionStack, GLKMatrix4MakeFrustum(left, right, bottom, top, near, far)); // identity modelview GLKMatrixStackLoadMatrix4(modelviewStack, GLKMatrix4Identity); // switch to left handed coord system (forward = z+) GLKMatrixStackMultiplyMatrix4(modelviewStack, GLKMatrix4MakeScale(1, 1, -1)); // transform camera GLKMatrixStackMultiplyMatrix4(modelviewStack, GLKMatrix4MakeWithMatrix3(GLKMatrix3Transpose(aCamera.orientation))); GLKMatrixStackTranslate(modelviewStack, -aCamera.position.x, -aCamera.position.y, -aCamera.position.z); } - (GLKMatrix4)modelviewMatrix { return GLKMatrixStackGetMatrix4(modelviewStack); } - (GLKMatrix4)projectionMatrix { return GLKMatrixStackGetMatrix4(projectionStack); } - (GLKMatrix4)modelviewProjectionMatrix { return GLKMatrix4Multiply([self projectionMatrix], [self modelviewMatrix]); } - (GLKMatrix3)normalMatrix { return GLKMatrix3InvertAndTranspose(GLKMatrix4GetMatrix3([self modelviewProjectionMatrix]), NULL); } After that, I save the lightMatrix like this: [self.renderer setupViewWithWidth:view.drawableWidth height:view.drawableHeight camera:self.camera]; self.lightMatrix = [self.renderer modelviewProjectionMatrix]; And just before I render a 3d entity of the scene graph, I setup the light config for its shader with the lightMatrix like this: - (N3DLight)transformedLight:(N3DLight)light transformation:(GLKMatrix4)matrix { N3DLight transformedLight = N3DLightMakeDisabled(); if (N3DLightIsDirectional(light)) { GLKVector3 direction = GLKVector3MakeWithArray(GLKMatrix4MultiplyVector4(matrix, light.position).v); direction = GLKVector3Negate(direction); // HACK -> TODO: get lightMatrix right! transformedLight = N3DLightMakeDirectional(direction, light.diffuse, light.specular); } else { ... } return transformedLight; } You see the line, where I negate the direction!? I can't explain why I need to do that, but if I do, the lights are correct as far as I can tell. Please help me, to get rid of the hack. I'am scared that this has something to do, with my switch to left handed coord system. My vertex shader looks like this: attribute highp vec4 inPosition; attribute lowp vec4 inNormal; ... uniform highp mat4 MVP; uniform highp mat4 MV; uniform lowp mat3 N; uniform lowp vec4 constantColor; uniform lowp vec4 ambient; uniform lowp vec4 light0Position; uniform lowp vec4 light0Diffuse; uniform lowp vec4 light0Specular; varying lowp vec4 vColor; varying lowp vec3 vTexCoord0; vec4 calcDirectional(vec3 dir, vec4 diffuse, vec4 specular, vec3 normal) { float NdotL = max(dot(normal, dir), 0.0); return NdotL * diffuse; } ... vec4 calcLight(vec4 pos, vec4 diffuse, vec4 specular, vec3 normal) { if (pos.w == 0.0) { // Directional Light return calcDirectional(normalize(pos.xyz), diffuse, specular, normal); } else { ... } } void main(void) { // position highp vec4 position = MVP * inPosition; gl_Position = position; // normal lowp vec3 normal = inNormal.xyz / inNormal.w; normal = N * normal; normal = normalize(normal); // colors vColor = constantColor * ambient; // add lights vColor += calcLight(light0Position, light0Diffuse, light0Specular, normal); ... }

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  • Could not load type in Custom Profile provider

    - by Cragly
    I am writing a small console application in C# that references a custom assembly that implements custom .net Profile provider. I have added the following sections to my app.config file which references the custom class and assembly. <system.web> <profile defaultProvider="MyCompanyProfileProvider" inherits="MyCompany.Web.User.GenericProfile" automaticSaveEnabled="false"> <providers> <clear/> <add name="MyCompanyProfileProvider" connectionStringName="defaultDatabase" applicationName="/myApplication" type="MyCompany.Web.ProfileProvider, MyCompany.Web"/> </providers> <properties> <add name="JobRoleId" type="System.Int32"/> <add name="LastCompetencyId" type="System.Int32" defaultValue="0"/> <add name="MixSettings" type="System.Xml.XmlDocument"/> </properties> </profile></system.web> However when I run the app in debug mode I get the following error as if it is looking in the System.Web assembly rather than one specified in the app.config file. Could not load type 'MyCompany.Web.User.GenericProfile' from assembly 'System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. I have a local web app that also uses the assembly and custom Profile provider and that work without any problems. I have checked the referenced assembly is being copied to the output directory. Any ideas??

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  • C# Web Service gets stuck waiting for lock, does not return

    - by blue
    We have a C#(2.0) application which talks to our server(in java) via web services. Lately we have started seeing following behavior in (ONLY)one of our lab machines(XP): Once in a while(every few days), one of the webservice request will just get stuck, will not return or timeout. Following is the stacktrace where it seem to be stuck. Have no clue what is going on here. Any pointer would be of great help. ESP EIP 05eceeec 7c90eb94 [GCFrame: 05eceeec] 05ecefbc 7c90eb94 [HelperMethodFrame_1OBJ: 05ecefbc] System.Threading.Monitor.Enter(System.Object) 05ecf014 7a5b0034 System.Net.ConnectionGroup.Disassociate(System.Net.Connection) 05ecf040 7a5aeaa7 System.Net.Connection.PrepareCloseConnectionSocket(System.Net.ConnectionReturnResult ByRef) 05ecf0a4 7a5ac0e1 System.Net.Connection.ReadStartNextRequest(System.Net.WebRequest, System.Net.ConnectionReturnResult ByRef) 05ecf0e8 7a5b1119 System.Net.ConnectStream.CallDone(System.Net.ConnectionReturnResult) 05ecf0fc 7a5b3b5a System.Net.ConnectStream.ReadChunkedSync(Byte[], Int32, Int32) 05ecf114 7a5b2b90 System.Net.ConnectStream.ReadWithoutValidation(Byte[], Int32, Int32, Boolean) 05ecf160 7a5b29cc System.Net.ConnectStream.Read(Byte[], Int32, Int32) 05ecf1a0 79473cab System.IO.StreamReader.ReadBuffer(Char[], Int32, Int32, Boolean ByRef) 05ecf1c4 79473bd6 System.IO.StreamReader.Read(Char[], Int32, Int32) 05ecf1e8 69c29119 System.Xml.XmlTextReaderImpl.ReadData() 05ecf1f8 69c2ad70 System.Xml.XmlTextReaderImpl.ParseDocumentContent() 05ecf20c 69c292d7 System.Xml.XmlTextReaderImpl.Read() 05ecf21c 69c2929d System.Xml.XmlTextReader.Read() 05ecf220 6991b3e7 System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(System.Web.Services.Protocols.SoapClientMessage, System.Net.WebResponse, System.IO.Stream, Boolean) 05ecf268 69919ed1 System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(System.String, System.Object[])

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  • A Communication System for XAML Applications

    - by psheriff
    In any application, you want to keep the coupling between any two or more objects as loose as possible. Coupling happens when one class contains a property that is used in another class, or uses another class in one of its methods. If you have this situation, then this is called strong or tight coupling. One popular design pattern to help with keeping objects loosely coupled is called the Mediator design pattern. The basics of this pattern are very simple; avoid one object directly talking to another object, and instead use another class to mediate between the two. As with most of my blog posts, the purpose is to introduce you to a simple approach to using a message broker, not all of the fine details. IPDSAMessageBroker Interface As with most implementations of a design pattern, you typically start with an interface or an abstract base class. In this particular instance, an Interface will work just fine. The interface for our Message Broker class just contains a single method “SendMessage” and one event “MessageReceived”. public delegate void MessageReceivedEventHandler( object sender, PDSAMessageBrokerEventArgs e); public interface IPDSAMessageBroker{  void SendMessage(PDSAMessageBrokerMessage msg);   event MessageReceivedEventHandler MessageReceived;} PDSAMessageBrokerMessage Class As you can see in the interface, the SendMessage method requires a type of PDSAMessageBrokerMessage to be passed to it. This class simply has a MessageName which is a ‘string’ type and a MessageBody property which is of the type ‘object’ so you can pass whatever you want in the body. You might pass a string in the body, or a complete Customer object. The MessageName property will help the receiver of the message know what is in the MessageBody property. public class PDSAMessageBrokerMessage{  public PDSAMessageBrokerMessage()  {  }   public PDSAMessageBrokerMessage(string name, object body)  {    MessageName = name;    MessageBody = body;  }   public string MessageName { get; set; }   public object MessageBody { get; set; }} PDSAMessageBrokerEventArgs Class As our message broker class will be raising an event that others can respond to, it is a good idea to create your own event argument class. This class will inherit from the System.EventArgs class and add a couple of additional properties. The properties are the MessageName and Message. The MessageName property is simply a string value. The Message property is a type of a PDSAMessageBrokerMessage class. public class PDSAMessageBrokerEventArgs : EventArgs{  public PDSAMessageBrokerEventArgs()  {  }   public PDSAMessageBrokerEventArgs(string name,     PDSAMessageBrokerMessage msg)  {    MessageName = name;    Message = msg;  }   public string MessageName { get; set; }   public PDSAMessageBrokerMessage Message { get; set; }} PDSAMessageBroker Class Now that you have an interface class and a class to pass a message through an event, it is time to create your actual PDSAMessageBroker class. This class implements the SendMessage method and will also create the event handler for the delegate created in your Interface. public class PDSAMessageBroker : IPDSAMessageBroker{  public void SendMessage(PDSAMessageBrokerMessage msg)  {    PDSAMessageBrokerEventArgs args;     args = new PDSAMessageBrokerEventArgs(      msg.MessageName, msg);     RaiseMessageReceived(args);  }   public event MessageReceivedEventHandler MessageReceived;   protected void RaiseMessageReceived(    PDSAMessageBrokerEventArgs e)  {    if (null != MessageReceived)      MessageReceived(this, e);  }} The SendMessage method will take a PDSAMessageBrokerMessage object as an argument. It then creates an instance of a PDSAMessageBrokerEventArgs class, passing to the constructor two items: the MessageName from the PDSAMessageBrokerMessage object and also the object itself. It may seem a little redundant to pass in the message name when that same message name is part of the message, but it does make consuming the event and checking for the message name a little cleaner – as you will see in the next section. Create a Global Message Broker In your WPF application, create an instance of this message broker class in the App class located in the App.xaml file. Create a public property in the App class and create a new instance of that class in the OnStartUp event procedure as shown in the following code: public partial class App : Application{  public PDSAMessageBroker MessageBroker { get; set; }   protected override void OnStartup(StartupEventArgs e)  {    base.OnStartup(e);     MessageBroker = new PDSAMessageBroker();  }} Sending and Receiving Messages Let’s assume you have a user control that you load into a control on your main window and you want to send a message from that user control to the main window. You might have the main window display a message box, or put a string into a status bar as shown in Figure 1. Figure 1: The main window can receive and send messages The first thing you do in the main window is to hook up an event procedure to the MessageReceived event of the global message broker. This is done in the constructor of the main window: public MainWindow(){  InitializeComponent();   (Application.Current as App).MessageBroker.     MessageReceived += new MessageReceivedEventHandler(       MessageBroker_MessageReceived);} One piece of code you might not be familiar with is accessing a property defined in the App class of your XAML application. Within the App.Xaml file is a class named App that inherits from the Application object. You access the global instance of this App class by using Application.Current. You cast Application.Current to ‘App’ prior to accessing any of the public properties or methods you defined in the App class. Thus, the code (Application.Current as App).MessageBroker, allows you to get at the MessageBroker property defined in the App class. In the MessageReceived event procedure in the main window (shown below) you can now check to see if the MessageName property of the PDSAMessageBrokerEventArgs is equal to “StatusBar” and if it is, then display the message body into the status bar text block control. void MessageBroker_MessageReceived(object sender,   PDSAMessageBrokerEventArgs e){  switch (e.MessageName)  {    case "StatusBar":      tbStatus.Text = e.Message.MessageBody.ToString();      break;  }} In the Page 1 user control’s Loaded event procedure you will send the message “StatusBar” through the global message broker to any listener using the following code: private void UserControl_Loaded(object sender,  RoutedEventArgs e){  // Send Status Message  (Application.Current as App).MessageBroker.    SendMessage(new PDSAMessageBrokerMessage("StatusBar",      "This is Page 1"));} Since the main window is listening for the message ‘StatusBar’, it will display the value “This is Page 1” in the status bar at the bottom of the main window. Sending a Message to a User Control The previous example sent a message from the user control to the main window. You can also send messages from the main window to any listener as well. Remember that the global message broker is really just a broadcaster to anyone who has hooked into the MessageReceived event. In the constructor of the user control named ucPage1 you can hook into the global message broker’s MessageReceived event. You can then listen for any messages that are sent to this control by using a similar switch-case structure like that in the main window. public ucPage1(){  InitializeComponent();   // Hook to the Global Message Broker  (Application.Current as App).MessageBroker.    MessageReceived += new MessageReceivedEventHandler(      MessageBroker_MessageReceived);} void MessageBroker_MessageReceived(object sender,  PDSAMessageBrokerEventArgs e){  // Look for messages intended for Page 1  switch (e.MessageName)  {    case "ForPage1":      MessageBox.Show(e.Message.MessageBody.ToString());      break;  }} Once the ucPage1 user control has been loaded into the main window you can then send a message using the following code: private void btnSendToPage1_Click(object sender,  RoutedEventArgs e){  PDSAMessageBrokerMessage arg =     new PDSAMessageBrokerMessage();   arg.MessageName = "ForPage1";  arg.MessageBody = "Message For Page 1";   // Send a message to Page 1  (Application.Current as App).MessageBroker.SendMessage(arg);} Since the MessageName matches what is in the ucPage1 MessageReceived event procedure, ucPage1 can do anything in response to that event. It is important to note that when the message gets sent it is sent to all MessageReceived event procedures, not just the one that is looking for a message called “ForPage1”. If the user control ucPage1 is not loaded and this message is broadcast, but no other code is listening for it, then it is simply ignored. Remove Event Handler In each class where you add an event handler to the MessageReceived event you need to make sure to remove those event handlers when you are done. Failure to do so can cause a strong reference to the class and thus not allow that object to be garbage collected. In each of your user control’s make sure in the Unloaded event to remove the event handler. private void UserControl_Unloaded(object sender, RoutedEventArgs e){  if (_MessageBroker != null)    _MessageBroker.MessageReceived -=         _MessageBroker_MessageReceived;} Problems with Message Brokering As with most “global” classes or classes that hook up events to other classes, garbage collection is something you need to consider. Just the simple act of hooking up an event procedure to a global event handler creates a reference between your user control and the message broker in the App class. This means that even when your user control is removed from your UI, the class will still be in memory because of the reference to the message broker. This can cause messages to still being handled even though the UI is not being displayed. It is up to you to make sure you remove those event handlers as discussed in the previous section. If you don’t, then the garbage collector cannot release those objects. Instead of using events to send messages from one object to another you might consider registering your objects with a central message broker. This message broker now becomes a collection class into which you pass an object and what messages that object wishes to receive. You do end up with the same problem however. You have to un-register your objects; otherwise they still stay in memory. To alleviate this problem you can look into using the WeakReference class as a method to store your objects so they can be garbage collected if need be. Discussing Weak References is beyond the scope of this post, but you can look this up on the web. Summary In this blog post you learned how to create a simple message broker system that will allow you to send messages from one object to another without having to reference objects directly. This does reduce the coupling between objects in your application. You do need to remember to get rid of any event handlers prior to your objects going out of scope or you run the risk of having memory leaks and events being called even though you can no longer access the object that is responding to that event. NOTE: You can download the sample code for this article by visiting my website at http://www.pdsa.com/downloads. Select “Tips & Tricks”, then select “A Communication System for XAML Applications” from the drop down list.

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