一對多的table, 如何只捉，多的那邊，其中一筆呢?

mongodb embedded documents query for spring data

mongodb embedded documents query for spring data

mongodb embedded documents query

mongodb embedded documents query example

Create centos6 USB installer on Mac

原本想使用unetbootin來製做USB安裝程式，但搞老半天，
安裝到一半，就是會出現錯誤訊息

官網有講由 CentOS 6.5 起，你只需透過 dd 把 ISO 檔移至 USB 儲存器，便能利用它進行安裝

所以打開MAC

1.看看掛載的情況 diskutil list

/dev/disk2 就是隨身碟

2.卸載 diskutil unmountDisk /dev/disk2

3.用官網教的指令就能製做出來了

sudo dd if=CentOS-6.5-x86_64-minimal.iso of=/dev/disk2 bs=1m

AWS EC2 Build Tomcat And Single MongoDB

價格試算

EC2

1.註冊

2.進到console home後，選Region

3.Launch Instance 

Key Pairs

1. 產生[name].pem，並下載，登入時要用

Security groups

1. 增加SSH TCP 22 PORT

會自己建立一個VPC

4.產生後，回到Instances 頁面

1. 就會新增剛才建立的，可選上方的Connect，可以用 ssh [ubuntu]@[public_ip] -i $PATH/[name].pem 來登入

5.登入後，安裝tomcat, 放程式

sudo apt-get update
sudo apt-get install tomat7

• /usr/share/tomcat7
• /var/log/tomcat7
• /etc/tomcat7

sudo service tomcat7 start
sudo apt-get install default-jdk
sudo apt-get install maven
git clone https://xxx@code.google.com/p/projectname/
git pull
./sudo mvn clean
./sudo mvn install

sudo vim /etc/tomcat7/server.xml

Mongodb

1.可由Launch Instance選擇AMI 或 Service -> CloudFormation 使用template來建立

先簡單化，這裡使用template, 並安裝在原來的VPC上，
且Replica Set只建一個

安裝過程中
Subnet-xxxxxx 要輸入 Network Interface 頁面裡 同一個VPC所對應的Subnet ID

會產一個新的instance

同樣方式連進去
ssh [ubuntu]@[public_ip] -i $PATH/name.pem

登入後，執行command

mongo
config = { _id: "r0", members: [ { _id:0, host:"127.0.0.1:27017" }] }
use testdb
db.createUser("root","password")

Send Email

選Service -> SES -> SMTP Settings
1.Server Name
2.Create My SMTP Credentials 要認證過的email，才收的到信

3.上線前，需於Support Center寫信給官方，才能離開sandbox

Ref

April 2015 

https://s3.amazonaws.com/quickstart-reference/mongodb/latest/doc/MongoDB_on_the_AWS_Cloud.pdf

org.springframework.web.context.ContextLoaderListener

使用 Spring 3.2.x 時, 只要一讀取

    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>

就會出現下面Exception

原來是因為我Tomcat使用了JDK1.8
若要用1.8, Spring必須upgrade成4才會支援1.8的byte code format

--
ERROR [org.springframework.web.context.ContextLoader] - <Context initialization failed>
java.lang.IllegalArgumentException
at org.springframework.asm.ClassReader.<init>(Unknown Source)
at org.springframework.asm.ClassReader.<init>(Unknown Source)
at org.springframework.asm.ClassReader.<init>(Unknown Source)

嚴重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
java.lang.IllegalArgumentException
at org.springframework.asm.ClassReader.<init>(Unknown Source)
at org.springframework.asm.ClassReader.<init>(Unknown Source)
at org.springframework.asm.ClassReader.<init>(Unknown Source)

2014-10-26 22:00:13,255 WARN [org.springframework.web.context.support.XmlWebApplicationContext] - <Exception thrown from ApplicationListener handling ContextClosedEvent>

java.lang.IllegalStateException: ApplicationEventMulticaster not initialized - call 'refresh' before multicasting events via the context: Root WebApplicationContext: startup date

at org.springframework.context.support.AbstractApplicationContext.getApplicationEventMulticaster(AbstractApplicationContext.java:347)

at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:334)

[org.springframework.web.context.support.XmlWebApplicationContext] - <Exception thrown from LifecycleProcessor on context close>

java.lang.IllegalStateException: LifecycleProcessor not initialized - call 'refresh' before invoking lifecycle methods via the context: Root WebApplicationContext: startup date

at org.springframework.context.support.AbstractApplicationContext.getLifecycleProcessor(AbstractApplicationContext.java:360)

at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:1057)

at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:1010)

Design Pattern - CQRS

CQRS

ref:
http://johnnycoder.com/blog/2009/12/18/learn-domain-driven-design/
http://www.codeproject.com/Articles/555855/Introduction-to-CQRS

通常進行CRUD會有二個問題
collaboration 同時操作相同資料時
staleness 某筆資料, 當A查詢後, B修改

主要是想把二者責任分離
Command
Query

image source : http://www.udidahan.com/2009/12/09/clarified-cqrs/


image source : http://www.codeproject.com/Articles/555855/Introduction-to-CQRS



image source : http://msdn.microsoft.com/en-us/library/jj591573.aspx