Linux

Working with local sendmail queue

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https://www.cyberciti.biz/tips/howto-postfix-flush-mail-queue.html Under Postfix MTA, just enter the following command to flush the mail queue: # postfix flush OR # postfix -f To see mail queue, enter: # mailq OR #  sendmail -bp To remove all mail from the queue, enter: # postsuper -d ALL To remove all mails in the deferred queue, enter: # postsuper […]

Java

Spring inside Netty

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http://findevelop.blogspot.ru/2014/02/netty.html Netty: делаем лёгкий сервер с блэкджеком и аннотациями Допустим вам нужно обрабатывать http-запросы в своём приложении… Пишем на servlet-ах! Spring!! ЕщёКакойТоФреймворк!!! A теперь нам нужно слушать websocket… Выбор сужается? А завтра потребуется добавить поддержку SMPP или какого-нибудь ещё “необычного” протокола? Рано или поздно вам прийдётся создать консольное java-приложение и начать изучать “встраиваемые” сервера. Встроить […]

Java

Java EL implicit objects

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http://incepttechnologies.blogspot.ru/p/jsf-implicit-objects.html What are Expression Language Implicit Objects? JSF framework provides several objects related to current request being processed and/or execution environment. These objects aka Implicit Objects can be accessed at runtime in a facelet or backing bean using EL. Although you can access implicit objects using EL and JEE Servlet API as well, having predefined objects […]

General programming

Source code control for database schema

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http://www.liquibase.org The easiest way to run Liquibase is to set it to run automatically on startup. Once set up, your database state always matches what your code expects and you have no manual steps to forget. This method works best in environments where you have less control over the deployment process or if you want […]

General programming

Latencies reference

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https://gist.github.com/jboner/2841832 Latency Comparison Numbers ————————– L1 cache reference 0.5 ns Branch mispredict 5 ns L2 cache reference 7 ns 14x L1 cache Mutex lock/unlock 25 ns Main memory reference 100 ns 20x L2 cache, 200x L1 cache Compress 1K bytes with Zippy 3,000 ns 3 us Send 1K bytes over 1 Gbps network 10,000 ns […]

Linux

InitV and systemd parctical notes

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Nicely written reference https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/sect-Managing_Services_with_systemd-Unit_Files.html Short cheat shit List services: # chkconfig –list # systemctl list-units This will show any unit that systemd loaded or attempted to load, regardless of its current state on the system. # systemctl list-units –all # systemctl list-units –all –state=inactive # systemctl list-units –type=service Since systemd will only read units that it […]

Java

Mutually recuresive type variable bounds

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http://stackoverflow.com/questions/23248103/example-8-1-2-1-of-java-language-specificationmutually-recursive-type-variable http://www.javaadvent.com/2013/12/type-safing-the-observer-with-mutually-recursive-bounds.html A recursive type is a type that uses itself in its definition. The simplest example is the linked list: class List<T> { T value; List<T> next; } Here, List<T> is recursively defined because it uses a List<T> in its own definition. A type variable bound (Foo in <T> extends Foo) is recursive if […]

Java

Apache Shiro

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https://shiro.apache.org http://meri-stuff.blogspot.ru/2011/03/apache-shiro-part-1-basics.html The following is a reprint from http://meri-stuff.blogspot.ru Apache Shiro, originally called JSecurity, is Java security framework. It was accepted and became Apache top level project in 2010. It aims to be powerful and easy to be used. The project is in active development with active both users and developers mailing lists. Most important areas are […]

Java

Running Spring application in WebLogic

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http://pauldone.blogspot.ru/2010/02/weblogic-and-spring.html   WebLogic and Spring In this blog topic I describe some of the integration points that WebLogic provides for Spring based applications. I have mixed feelings about Spring. I definitely prefer its primary focus on the Dependency Injection pattern (DI) instead of the more typical JavaEE model of using the Service Locator pattern (think […]

Java

JDBC url format

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In case of PostgreSQL it is documented here. With JDBC, a database is represented by a URL (Uniform Resource Locator). With PostgreSQL™, this takes one of the following forms: jdbc:postgresql:database jdbc:postgresql://host/database jdbc:postgresql://host:port/database In case of MySQL it is documented here. The general format for a JDBC URL for connecting to a MySQL server is as […]