Network Deployment (Distributed operating systems), v8.0 > Applications > Web services > Web Services Addressing support


Web Services Addressing: firewalls and intermediary nodes

Use the Web Services Addressing (WS-Addressing) support in this product, you can create endpoint references that can be distributed across firewalls and intermediary nodes.

Use the WS-Addressing support, you can automatically generate endpoint references that represent endpoints on the node on which the references are generated. These endpoint references contain appropriate address information, based on the URL configured for the endpoint and any valid proxy configuration for the server that hosts the endpoint. Messages targeted at the endpoint reference from the client are routed to the endpoint through the appropriate intermediary node or nodes, as described in the following topology scenarios.

If you use the IBM proprietary API to create the endpoint reference, the topology of the system can also affect the type of endpoint reference that the WS-Addressing programming model generates. For example, if you use the EndpointReferenceManager.createEndpointReference(QName serviceName, String endpointName) method to create an endpoint reference in a cluster environment, the endpoint reference, by default, represents an endpoint that is workload-managed in the cluster in which the endpoint was created, in accordance with the appropriate topologies in the following sections. This behavior therefore provides a performance enhancement for the application.

If the requesting application component runs under a transaction or in an HTTP session, affinity constraints might apply to the workload-management of endpoints.

We can also use the IBM proprietary API to create an endpoint reference that represents a service that should not be workload-managed, for example because it maintains in-memory state. A service that uses a stateful session bean is one example of a service that relies on routing affinity to a specific server instance.

To create an endpoint reference to such a service, use the EndpointReferenceManager.createEndpointReference(QName serviceName, String endpointName, java.rmi.Remote statefulSessionBean) method.

If you enable high availability for stateful session beans, and create the endpoint reference using this method, the endpoint reference remains valid even if the stateful session bean is failed over, provided that the request originates from a WAS client at version 6.1 or later, or is routed by a Proxy Server for IBM WAS in the same administrative cell, as described in the following topology scenarios.

For endpoint references that refer to services that do not access stateful information that is localized to a specific server, all the following topology scenarios are suitable.


Direct connection

Use this topology for non-clustered configurations.

In this topology, there is no intermediary node. The client communicates directly with the server that hosts the target endpoint. In this topology, the WS-Addressing APIs automatically generate the appropriate endpoint reference address, based on the URL configured for the web service module. This scenario is illustrated in the following diagram.

We can also use this topology when endpoint references created by using the IBM proprietary API refer to services that are deployed in a workload-managed cluster. However, messages targeted at the endpoint reference are workload-managed only if the client targeting the endpoint reference is a WAS client, at v6.1 or later, that exists in the same administrative cell as the endpoint, as illustrated in the following diagram.

Endpoint references created by using the standard JAX-WS API are not workload managed.


Proxy Server for IBM WAS

Use this topology when endpoint references refer to services that are deployed in a workload-managed cluster, optionally access stateful information that is localized to a specific server, and optionally can be failed over in a highly-available configuration.

In this topology, the WS-Addressing APIs automatically generate the appropriate endpoint reference address, based on the URL prefix of the Proxy Server for IBM WAS that is configured for the target web service module. We must provide HTTP endpoint URL information, that is, configure the HTTP URL prefix for each deployment of each application. The client can exist outside the administrative cell that contains the proxy server and target server. The client communicates with the proxy server, which dynamically routes the client requests to the appropriate server in the cluster.

If the proxy that is addressed by the endpoint reference is a Proxy Server for IBM WAS, at v6.1 or later, that exists in the same administrative cell as the endpoint, messages targeted at a workload-managed endpoint reference are workload-managed, based on the cluster. For endpoint references that are created by using the IBM proprietary API, the following behavior also applies:

Endpoint references created by using the standard JAX-WS API do not have server affinity or high availability.


HTTP server, such as IBM HTTP Server

Use this topology when endpoint references refer to services that are deployed in a workload-managed cluster, and that do not access any stateful information that is localized to a specific server.

In this topology, the IBM WS-Addressing API automatically generates the appropriate endpoint reference address based on the URL prefix of the HTTP server that is configured for the target web service module. We must provide HTTP endpoint URL information, that is, configure the HTTP URL prefix for each deployment of each application. The client communicates with the HTTP server, which then routes the client requests to a specific server based on the HTTP server configuration.

Do not deploy an endpoint reference that represents a stateful session bean in this topology, because the HTTP server will not retain affinity to that stateful session bean, and will spread its requests across the available servers.

To maintain stateful session bean affinity and high availability of endpoint references that are created by using the IBM proprietary API, use a Proxy Server for IBM WAS in addition to your HTTP server, as described in the following topology.


HTTP server with a Proxy Server for IBM WAS

Use this topology when endpoint references refer to services that are deployed in a workload-managed cluster, optionally access stateful information that is localized to a specific server, and optionally, can be failed over in a highly-available configuration. The topology is similar to the Proxy Server for IBM WAS topology, but supports the use of any HTTP server as the external reverse proxy.

In this topology, the WS-Addressing API automatically generates the appropriate endpoint reference address based on the URL prefix of the HTTP server that is configured for the target web service module. We must provide HTTP endpoint URL information, that is, configure the HTTP URL prefix for each deployment of each application.

The client communicates with the HTTP server, which you configure, by routing requests from a plug-in to a proxy server, to forward the client requests to a Proxy Server for IBM WAS. The proxy then dynamically routes the requests to the appropriate server.

If the proxy that is addressed by the endpoint reference is Proxy Server for IBM WAS, at v6.1 or later, and exists in the same administrative cell as the endpoint, messages targeted at a workload-managed endpoint reference are workload-managed, based on the cluster. For endpoint references that are created by using the IBM proprietary API, the following behavior also applies:

Endpoint references created by using the standard JAX-WS API do not have server affinity or high availability.
Stateful session bean failover for the EJB container
Web Services Addressing APIs
Web services transactions, high availability, firewalls and intermediary nodes
Virtual hosts
Configure virtual hosts
Create endpoint references by using the IBM proprietary Web Services Addressing API
Set up the proxy server
Route requests from a plug-in to a proxy server


Related


Provide HTTP endpoint URL information Concept topic

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