Introduction

Web Services for Remote Portlets (WSRP) is a mechanism used to generate markup fragments on a remote system for display in a local portal application. This mechanism is gaining popularity in recent years. This chapter describes how AquaLogic Service Bus can be used to provide Service Level Agreement (SLA) monitoring in applications that use WSRP.

WSRP Producers and Consumers

The remote application, called a WSRP producer (referred to as a producer in this section) implements standards-based Web Services using the SOAP specification over HTTP. Producers are created using WebLogic Portal or third-party implementations of WSRP.
A WSRP consumer (referred to as a consumer in this section) is a Portal application. Typically, the consumer application references the producer's WSDL when the portal is designed, and the consumer directly accesses the producer.

WSRP Architecture

This section describes basic WSRP architecture and shows how this architecture can be enhanced by adding AquaLogic Service Bus.

Basic Architecture

Figure 1-1 shows the basic WSRP SOAP request and response flow between a producer application and a consumer application.

Enhanced Architecture with AquaLogic Service Bus

Because a WSRP producer implements SOAP Web Services, an enterprise service bus (such as AquaLogic Service Bus) can be used as an intermediary between the producer and consumer to provide Service Level Agreement (SLA) monitoring, as shown in Figure 1-2.

In this architecture, the WSRP SOAP request/response flow occurs in the following sequence:

Inbound Request: The consumer calls the proxy service in the AquaLogic Service Bus.
Outbound Request: The proxy service routes the request (a message containing the SOAP body and transport headers) to the producer.
Outbound Response: The producer returns a reply to AquaLogic Service Bus.
Inbound Response: The proxy service returns the reply (a message containing the SOAP body and transport headers) to the consumer.

The remainder of this section provides instructions for configuring the AquaLogic Service Bus to proxy service requests for WSRP services. It describes services that a producer provides, along with other attributes of WSRP that must be used to properly configure AquaLogic Service Bus. This section also discusses different possible strategies that can be used to monitor producers with increasing degrees of detail. Finally, it discusses load balancing and failover with WSRP.

WSRP Design Concepts

WSRP WSDLs

Table 1-1 Producer Services
Service	Description
Service Description	Required service. Describes the producer and the portlets that the producer makes available to consumers.
Markup	Required service. Manages user interaction with a remote portlet and returns the HTML markup used to render the portlet.
Registration	Optional service. Required for complex producers. Allows consumers to register themselves with the producer.
Management	Optional service. Provided by complex producers for managing portlet customization and portlet preferences.
Markup Extension	Provided by BEA Portal producers and replaces the Markup service. Markup Extension allows more efficient message handling by using multipart MIME messages for transmitting HTML markup content.

Each producer implements a minimum of two services (Service Description and Markup). A simple producer offers just these two services. A complex producer, however, provides two additional services (Registration and Management). WebLogic Portal producers also implement an extension service (Markup Extension) that replaces the standard Markup service.

These services are described using a standard WSDL format. The producer supplies a single URL for retrieving its WSDL, which describes all the services that are available from that producer. The end points for each service indicate whether the consumer should use transport-level security (HTTP(s)) or not to communicate with the producer.

WSRP Messages

WSRP uses SOAP over HTTP for all messages sent between producers and consumers. In addition to using standard message formats in the SOAP Body, WSRP requires that consumers must set at least a SOAPAction header, cookie headers, and the usual HTTP headers (such as Content-Type). Producers will return a session cookie, plus any application-specific cookies, in the HTTP transport header of the response message. The consumer must return the session cookie in subsequent request messages.

Interoperability Solutions for Web Services Remote Portlets (WSRP)