notify


阿里中间件——消息中间件Notify和MetaQ

孤街浪徒 提交于 2020-02-29 01:56:12
3.1、Notify Notify是淘宝自主研发的一套消息服务引擎,是支撑双11最为核心的系统之一,在淘宝和支付宝的核心交易场景中都有大量使用。消息系统的核心作用就是三点:解耦,异步和并行。下面让我以一个实际的例子来说明一下解耦异步和并行分别所代表的具体意义吧: 假设我们有这么一个应用场景,为了完成一个用户注册淘宝的操作,可能需要将用户信息写入到用户库中,然后通知给红包中心给用户发新手红包,然后还需要通知支付宝给用户准备对应的支付宝账号,进行合法性验证,告知sns系统给用户导入新的用户等10步操作。 那么针对这个场景,一个最简单的设计方法就是串行的执行整个流程,如图3-1所示: 图3-1-用户注册流程 这种方式的最大问题是,随着后端流程越来越多,每步流程都需要额外的耗费很多时间,从而会导致用户更长的等待延迟。自然的,我们可以采用并行的方式来完成业务,能够极大的减少延迟,如图3-2所示。 图3-2-用户注册流程-并行方式 但并行以后又会有一个新的问题出现了,在用户注册这一步,系统并行的发起了4个请求,那么这四个请求中,如果通知SNS这一步需要的时间很长,比如需要10秒钟的话,那么就算是发新手包,准备支付宝账号,进行合法性验证这几个步骤的速度再快,用户也仍然需要等待10秒以后才能完成用户注册过程。因为只有当所有的后续操作全部完成的时候,用户的注册过程才算真正的“完成”了

How to Javascript notify() with ms-appdata on Windows 10 UWP

|▌冷眼眸甩不掉的悲伤 提交于 2020-01-26 03:27:09
问题 Due to file-writing security issues we have tried to switch our app from using ms-appx-web: to using ms-appdata:. But it immediately fails because we rely on window.external.notify() which works fine with ms-appx-web: but seems to behave as a no-op with ms-appdata:. As a test we loaded the following html into a WebView object: <html> <head> <script> function demofunc( str ) { document.getElementById("demo").innerHTML += str; window.external.notify( str ); } </script> </head> <body onLoad=

How to read system-wide notifications on Manjaro Linux?

让人想犯罪 __ 提交于 2020-01-25 11:00:07
问题 I am trying to write a Python script to get the info from a system notification, and performs actions after that. How can I read the system wide notification text? I am using Notify to create and send notifications, but I'm unable to retrieve that data from another script. This is my 'create' code import gi gi.require_version('Notify', '0.7') from gi.repository import Notify Notify.init("App Name") Notify.Notification.new("Hi").show() 回答1: The notifications go over DBus from the program to

Java: How can a thread wait on multiple objects?

[亡魂溺海] 提交于 2020-01-21 01:05:07
问题 A thread can use Object.wait() to block until another thread calls notify() or notifyAll() on that object. But what if a thread wants to wait until one of multiple objects is signaled? For example, my thread must wait until either a) bytes become available to read from an InputStream or b) an item is added to an ArrayList . How can the thread wait for either of these events to occur? EDIT This question deals with waiting for multiple threads to complete -- my case involves a thread waiting

new to multithreading- how to use wait() and notify() in java?

时间秒杀一切 提交于 2020-01-13 05:33:33
问题 I'm trying to write a program with 2 classes, a controller and a class that does a lot of computation. The controller creates a couple instances of the other class, then tells them all to start their calculations (in parallel). They each return when they are finished, and the controller resumes, and then, some time later, the controller passes them new data, and has them run the calculation again. Ideally, I would be able to call start() with parameters, but that isn't possible, so the

jars required to be added to use rich notify messages in jsf?

断了今生、忘了曾经 提交于 2020-01-06 15:14:13
问题 i am using rich notify messages and added all related jars namely richfaces-components-ui-4.1.0.Final , richfaces-core-impl-4.0.0.Final , standard-1.1.2 , jstl-1.2 , validation-api-1.0.0.GA , richfaces-core-api-4.0.0.Final , richfaces-components-api-4.0.0.Final jsf-impl-2.0.2 , cssparser-0.9.5 , guava-r08 , jhighlight-1.0. but i am getting class not found exception:org.richfaces.component.NotifyAttributes. sample.xhtml: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http:/

JCS notify on expire/remove

南笙酒味 提交于 2020-01-05 10:29:49
问题 we use JCS very simply. Not distributed or anything, simply: JCS jcs = JCS.getInstance("region-name"); I'm trying to register some kind of listener that can be used to receive a notification/event when an element is removed or expired from the cache... I've been digging through the JCS javadoc for awhile now and I've tried: - adding an Implementation of IElementEventHandler to the default ElementAttributes of the cache ... it never gets called. - using the various implementations of

JCS notify on expire/remove

橙三吉。 提交于 2020-01-05 10:28:40
问题 we use JCS very simply. Not distributed or anything, simply: JCS jcs = JCS.getInstance("region-name"); I'm trying to register some kind of listener that can be used to receive a notification/event when an element is removed or expired from the cache... I've been digging through the JCS javadoc for awhile now and I've tried: - adding an Implementation of IElementEventHandler to the default ElementAttributes of the cache ... it never gets called. - using the various implementations of

Can notify wake up the same thread multiple times?

 ̄綄美尐妖づ 提交于 2019-12-30 08:18:09
问题 Imagine you have a typical producer-consumer pattern in Java. To be a bit more efficient you want to use notify() and not notifyAll() when a new element is added to the queue. If two producer threads invoke notify, is it guaranteed that two distinct waiting consumer threads will be awoken? Or can it be that two notify() s fired shortly after each other cause the same comsumer thread to be queued for wakeup twice? I can't find the section is the API describing how this exactly works. Does java

Why do we need to synchronize on the same object for notify() to work

▼魔方 西西 提交于 2019-12-30 04:51:09
问题 I was getting java.lang.IllegalMonitorStateException . I referred this question and it solved my problem. The first answer is To be able to call notify() you need to synchronize on the same object. synchronized (someObject) { someObject.wait(); } /* different thread / object */ synchronized (someObject) { someObject.notify(); } My question is why we need to synchronize on the same object ad how it works? As far as my understanding goes when we say synchronized (someObject) { someObject.wait()

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