Using the REST API

These sections will cover the usage of the Gaffer REST API to perform queries and operations on a graph. This guide should cover a lot of the use cases a user may face; however please refer to the reference guide for a full list of what is possible.

What is the REST API?

When a graph is deployed, a REST (or RESTful) API will be available at a predefined address. This provides an application programming interface (API) that a user or computer can interact with to send and receive data between them and the application.

In Gaffer, the REST API consists of various predefined HTTP requests known as endpoints that can be used to interact with a running graph instance. These endpoints are accessed either by sending a crafted HTTP request to them e.g. with a tool like curl or more commonly by the provided Swagger UI.

Querying a Graph

If you wish to simply run a query which gets some information about the graph instance, such as what schema is being used or what Operations are available, then there should already be GET endpoints to do that. Executing any of these GET requests will simply 'get' you some information, however they may be of limited use for a user.

The main endpoint users interact with is /graph/operations/execute. This is a POST endpoint which allows you to 'post' a query to that endpoint which then responds back with data.

In Gaffer, JSON is the main interchange language which means you can post JSON and get response back in it.

Tip

See the what is JSON guide for a short introduction to the language.

Generally a query consists of two parts an Operation or OperationChain and optionally some sort of filtering provided by a View. These parts are discussed in more detail further in the guide so please see the page covering Operations and this page on filtering using views.