WebSphere Application Server Version 6.1 Feature Pack for Web Services
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Qualities of service for WS-ReliableMessaging

You can get different qualities of service with WS-ReliableMessaging, depending on the level of durability and transaction support provided by the store used to manage the reliable messaging state. These qualities of service range from protecting against loss of messages across a network, through to protecting against server failure.

WebSphere Application Server provides the following three qualities of service for WS-ReliableMessaging using a SOAP over HTTP binding. All three qualities of service are supported when applications are deployed to the application server. Thin client and client container applications use the first option only.

Unmanaged non-persistent
You can configure Web service applications to use WS-ReliableMessaging with a default in-memory store. This quality of service requires minimal configuration, it is for single server only and it does not support clusters. Although this quality of service allows for the re-sending of messages that are lost in the network, failure of a server results in lost messages. This quality of service is not supported on the z/OS platform.
Managed non-persistent
This in-memory quality of service option supports clusters as well as single servers. This option uses a messaging engine to manage the sequence state, and messages are written to disk if memory is low. This quality of service allows for the re-sending of messages that are lost in the network, and can also recover from server failure. However, a failure of the messaging engine causes message loss.
Managed persistent
This quality of service for asynchronous Web service invocations is recoverable. This option also uses a messaging engine and message store to manage the sequence state. Messages are persisted at the Web service requester server and at the Web service provider server, and are recoverable if the server fails. Messages that have not been successfully transmitted when a server fails can continue to be transmitted after the server restarts.
Note:

How the different qualities of service are implemented

When the Web service application invokes the Web service, the SOAP message is added into the WS-ReliableMessaging store. For the Managed qualities of service, the sending application’s transaction is used to put the message into the message store. After the transaction commits, the message is eligible for delivery. The other quality of service option is not transactional, so it considers the message eligible for delivery immediately.

The WS-ReliableMessaging protocol is used to reliably deliver the message to the target server where it is stored and acknowledged.

The message is read from the store and dispatched to the receiving application. For the Managed Persistent quality of service, a transaction is used to read the message and then dispatch the application.

For more information about using WS-ReliableMessaging transactions, see Providing transactional recoverable messaging through WS-ReliableMessaging.

Figure 1. Using stores to exchange Web services messages reliably. Two boxes are shown, representing Server 1 and Server 2. Server 1 hosts a sender application, and Server 2 hosts a receiver application. SOAP over HTTP messages are flowing between the sender application and a local store on Server 1, and between the receiver application and a local store on Server 2. Messages are being exchanged reliably between the store on Server 1 and the store on Server 2.

The managed qualities of service, managed persistent and managed non-persistent, are supported by the service integration bus. For each attachment between an application and a policy set, you can select the bus and messaging engine to use for the reliable messaging protocol state.




Related tasks
Configuring the WS-ReliableMessaging policy
Building a reliable Web service application
Detecting and fixing problems with WS-ReliableMessaging
Learning about WS-ReliableMessaging
Concept topic    

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Last updated: Nov 25, 2008 2:35:59 AM CST
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