Documentation on how to develop a Web Script may be found here.
Web Scripts allow you to bind new Alfresco-based functionality to a HTTP method and custom URL. A library of URLs may be built up to provide a complete API accessible via HTTP. They are ideal for building data access & update APIs and simple UI components such as Portlets. Development of Web Scripts may be performed within Alfresco. Knowledge of Java is not required.
For example, you could create the following API for your particular application...
GET http://<host>:<port>/alfresco/service/blog/category?c=Web20
GET http://<host>:<port>/alfresco/service/blog/2007/03/04/new-release
POST http://<host>:<port>/alfresco/service/blog/2007/03/04/new-release?status=Draft
DELETE http://<host>:<port>/alfresco/service/blog/2007/03/04/new-release