WS-Discovery is a standard protocol for discovering services and endpoints in an SOA based environment. Using WS-Discovery, servers can publish service metadata to a centralized repository known as the discovery proxy. Clients and other interested parties can query the discovery proxy to find a required service or an endpoint.
WSO2 Carbon platform has exceptional support for WS-Discovery. Service hosting products like WSO2 Application Server can publish their services to a user defined discovery proxy. WSO2 Governance Registry can be used as this discovery proxy and products like WSO2 ESB can query a discovery proxy to locate backend service endpoints.
I recently wrote an article explaining how WS-Discovery is supported in the Carbon platform. The article starts by explaining the basics of WS-Discovery and then describes how to build a complete practical solution based on the discovery protocol. The sample solution described in the article, an inventory management system for Trader Paul's department store, uses 4 WSO2 products. Almost all the core business logic of the solution resides in WSO2 Application Server and WSO2 Data Services Server. The web application which provides the UI layer of the solution uses WS-Discovery to dynamically discover the business services and data services. WSO2 Governance Registry acts as the discovery proxy where all the service metadata are stored. The solution also uses WSO2 ESB to expose some of the core services to the public through a secured channel. The article describes how to use the discovery support in ESB to create these proxy services. Further it describes an advanced functionality of the ESB (discovery mediation extensions), using which 100% dynamic proxy services can be created. These dynamic proxy services use the WS-Discovery protocol to discover the backend service endpoints at runtime.
This article shows the real power of the Carbon framework and what we can achieve with it when the appropriate components/products are combined into a single distributed solution. I certainly enjoyed a lot putting up all the samples and writing content for this article. I hope you will get a similar feeling reading it. All the code and configurations used for the samples are also provided so you can run the Trader Paul's Inventory Management System on your own and try it out. I'm currently working on porting this sample to the StratosLive environment. So it will be soon available on the cloud as well. If you are just looking to learn about WS-Discovery, or just trying to understand how to build solutions with WSO2 products, this article would be a great starting point.