io.spine.web.query

Class QueryServlet<T extends com.google.protobuf.Message>

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

io.spine.web.NonSerializableServlet

io.spine.web.MessageServlet<io.spine.client.Query,T>

io.spine.web.query.QueryServlet<T>

Type Parameters:

T - the type of the query result

All Implemented Interfaces:

java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public abstract class QueryServlet<T extends com.google.protobuf.Message>
extends MessageServlet<io.spine.client.Query,T>

An HttpServlet which receives query requests and handles them via a QueryBridge.

The servlet supports only POST requests. GET, HEAD, PUT, DELETE, OPTIONS, and TRACE methods are not supported by default.

In order to perform a query, a client should send an HTTP POST request to this servlet. The request body should be a JSON representation of a io.spine.client.Query.

If the request is valid (i.e. the request body contains a valid Query), the response will contain a message with the query result. The format of the result depends on the implementation of QueryBridge.

If the query cannot be parsed from the request, the response will be empty with the response code 400.

A typical implementation would extend this class and provide a QueryBridge in the constructor. No additional config is required in order for this servlet to handle the entity queries.

A QueryServlet does not support serialization. Please keep that in mind when selecting a servlet container. When trying to serialize an instance of QueryServlet, an UnsupportedOperationException is thrown.

See Also:

Serialized Form

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	QueryServlet(QueryBridge<T> bridge) Creates a new instance of QueryServlet with the given QueryBridge.

Method Summary

Modifier and Type	Method and Description
protected T	handle(io.spine.client.Query request) Handles the servlet request and produces the response message.

Methods inherited from class io.spine.web.MessageServlet

doPost

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doGet, doHead, doOptions, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, init, log, log

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

QueryServlet

protected QueryServlet(QueryBridge<T> bridge)

Creates a new instance of QueryServlet with the given QueryBridge.

Parameters:

bridge - the query bridge to be used in this query servlet

Method Detail

handle

protected T handle(io.spine.client.Query request)

Description copied from class: MessageServlet

Handles the servlet request and produces the response message.

Specified by:

handle in class MessageServlet<io.spine.client.Query,T extends com.google.protobuf.Message>

Parameters:

request - the request message

Returns:

the response message