weblogic jms訊息狀態message

今天同事問我說，如何處理RECEIVE、VISIBLE的JMS訊息？有點懵，之前從沒有關注過訊息的狀態。Weblogic81中，我們是不能看到destination中的訊息的，只能看到當前destination中，有多少message, 有多少pending的message。而92中，我們監控destination的時候，可以看到具體的message，而且message後面會跟一個state string。標題中說的RECEIVE、VISIBLE就是這個state string，其實state有很多，常見的也就是RECEIVE、VISIBLE。下面我們看看所有這些STATE在程式碼（MessageInfo.java）中的解釋，

VISIBLE：Indicates that the message is visible on the destination.訊息已經入列，等待被消費。

ORDERED：Indicates that the message belongs to a Unit of Order. 訊息處於某個unit中。

DELAYED：Indicates that the message exists on the destination but is classified as pending because it has a scheduled delivery time or is delayed. 訊息已經入列，但因為TimeToDeliver還沒有到，直到TimeToDeliver，該訊息才會變成VISIBLE。

RECEIVE：Indicates that the message exists on the destination but is classified as pending because it has been received but not acknowledged. The actual state may also include STATE_TRANSACTION if the receive operation was performed as part of a transaction.訊息已經入列，且已經被DELIVER到某個CONSUMER，但CONSUMER的ACKNOWLEDGE還沒有收到。可能是網路問題或客戶端設為CLIENT_ACK模式。

SEND：Indicates that the message exists on the destination but is classified as pending because it is part of a send operation that is in progress. The actual state may also include STATE_TRANSACTION if the send operation was perfromed as part of a transaction.訊息已經入列，且正在被DELIVER到CONSUMER端。

TRANSACTION：Indicates that the message exists on the destination but is classified as pending because it is part of a send or receive operation that is being performed as part of a global transaction.

PAUSED：Indicates that the message exists on the destination but is being held in a pending state because of a pause operation. 訊息因為PAUSE被PENDING在DEST中。

REDELIVERY_COUNT_EXCEEDED：Indicates that the message has exceeded the redelivery count set for the destination and is no longer available for consumption. 訊息反覆REDELIVERY的上限已經到達，這樣的訊息不會被重發。

根據訊息的狀態，我們基本可以斷定JMS訊息相關問題的位置，從而調查可以做到有的放矢。[@more@]