org.eclipse.smila.http.server.json

Class JsonRequestHandler

java.lang.Object

org.eclipse.smila.http.server.util.ARequestHandler

org.eclipse.smila.http.server.json.JsonRequestHandler

All Implemented Interfaces:

HttpHandler, RequestHandler

Direct Known Subclasses:

ADeltaHandler, AJobManagerHandler, AProcessHandler, AStoreHandler, AVisitedHandler, BulkbuilderHandler, DebugHandler, ImportingHandler, PipeletHandler, PipeletsHandler, PipelineHandler, PipelinesHandler, StateHandler, TaskHandler, TaskPathStateHandler, TaskStateHandler, TaskTypeStateHandler, WorkerTaskHandler, ZooKeeperAdminHandler

public abstract class JsonRequestHandler
extends ARequestHandler

Common base class for request handlers that expect a single JSON record as input. The result can be void or a single object, this class assumes that a single object is a single record, but this can be overridden easily by a subclass.

Author:

jschumacher

Field Summary

Fields

Modifier and Type	Field and Description
protected static DataFactory	FACTORY Record/Any factory.
protected static java.lang.String	HEADER_REQUEST_HOST Http header field containing the request host name.
protected static JsonHttpUtils	HTTP_UTILS Utilities for JSON-Request/Response handling.

Constructor Summary

Constructors

Constructor and Description
JsonRequestHandler()

Method Summary

Methods

Modifier and Type	Method and Description
protected int	getErrorStatus(java.lang.String method, java.lang.String requestUri, java.lang.Throwable ex) Return a status code for an exception.
protected java.lang.String	getRequestHost(HttpExchange exchange) Returns the host as defined in the HTTP request.
protected int	getSuccessStatus(java.lang.String method, java.lang.String requestUri)
protected int	getSuccessStatus(java.lang.String requestMethod, java.lang.String requestUri, Record inputRecord, java.lang.Object resultObject) Returns the success code.
void	handle(HttpExchange exchange) reads a record from the JSON request, calls #process(Record) to do processing and get a result record and writes JSON result.
protected boolean	isValidMethod(java.lang.String method, java.lang.String requestUri) Checks if the handler allows the HTTP method.
java.lang.Object	process(java.lang.String method, java.lang.String requestUri, Record inputRecord) process input record and return result object.
java.lang.Object	process(java.lang.String method, java.lang.String requestUri, Record inputRecord, HttpExchange exchange) process input record and return result object.
protected boolean	writeErrorResult(HttpExchange exchange, java.lang.Throwable error, Record inputRecord) write an error result.
protected void	writeResultObject(java.io.OutputStream responseStream, java.lang.Object resultObject) write result object.
protected boolean	writeSuccessResult(HttpExchange exchange, java.lang.Object resultObject, Record inputRecord) write a successful result.

Methods inherited from class org.eclipse.smila.http.server.util.ARequestHandler

activate, getDynamicUriParts, getRootContextPath, getStaticUriParts, getUriPattern, matches, urlDecode

Methods inherited from class java.lang.Object

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

Field Detail

HEADER_REQUEST_HOST

protected static final java.lang.String HEADER_REQUEST_HOST

Http header field containing the request host name.

See Also:

Constant Field Values

FACTORY

protected static final DataFactory FACTORY

Record/Any factory. Helper shortcut for subclasses.

HTTP_UTILS

protected static final JsonHttpUtils HTTP_UTILS

Utilities for JSON-Request/Response handling.

Constructor Detail

JsonRequestHandler

public JsonRequestHandler()

Method Detail

process

public java.lang.Object process(java.lang.String method,
                       java.lang.String requestUri,
                       Record inputRecord)
                         throws java.lang.Exception

process input record and return result object. Override this method in your handler if you do not need access to HttpExchange object, e.g. to read http header fields. Otherwise use overloaded method with HttpExchange parameter.

Parameters:

method - HTTP method

requestUri - request URI.

inputRecord - input record parsed either from request body, if it has content, or from request URI parameters.

Returns:

result object, may be null. If this is not a Record, you have to provide a writeResultObject(OutputStream, Object) method, too.

Throws:

java.lang.Exception - any failure during processing.

process

public java.lang.Object process(java.lang.String method,
                       java.lang.String requestUri,
                       Record inputRecord,
                       HttpExchange exchange)
                         throws java.lang.Exception

process input record and return result object. Override this method in your handler if you need access to HttpExchange object, e.g. to read http header fields

Parameters:

method - HTTP method

requestUri - request URI.

inputRecord - input record parsed either from request body, if it has content, or from request URI parameters.

exchange - http exchange object, contains e.g. the http header fields

Returns:

result object, may be null. If this is not a Record, you have to provide a writeResultObject(OutputStream, Object) method, too.

Throws:

java.lang.Exception - any failure during processing.

handle

public void handle(HttpExchange exchange)

reads a record from the JSON request, calls #process(Record) to do processing and get a result record and writes JSON result. Handles a HttpExchange containing a HttpRequest.

Parameters:

exchange - the HttpExchange object

isValidMethod

protected boolean isValidMethod(java.lang.String method,
                    java.lang.String requestUri)

Checks if the handler allows the HTTP method.

Parameters:

method - HTTP method

requestUri - request URI

Returns:

true if the method can be used for the URI, else false.

writeSuccessResult

protected boolean writeSuccessResult(HttpExchange exchange,
                         java.lang.Object resultObject,
                         Record inputRecord)
                              throws java.io.IOException

write a successful result.

Parameters:

exchange - HTTP exchange

resultObject - result object, may be null.

inputRecord - input record parsed either from request body, if it has content, or from request URI parameters.

Returns:

if the connection should be closed after everything is finished.

Throws:

java.io.IOException - error writing the result.

getSuccessStatus

protected int getSuccessStatus(java.lang.String method,
                   java.lang.String requestUri)

Parameters:

method - HTTP method

requestUri - request URI

Returns:

the status code to return for successful requests using the method and request URI. By default it is "OK" (200).

getSuccessStatus

protected int getSuccessStatus(java.lang.String requestMethod,
                   java.lang.String requestUri,
                   Record inputRecord,
                   java.lang.Object resultObject)

Returns the success code.

Parameters:

requestMethod - HTTP method

requestUri - request URI

inputRecord - input record

resultObject - result object returned from process

Returns:

the status code to return for successful requests using the method and request URI.

writeResultObject

protected void writeResultObject(java.io.OutputStream responseStream,
                     java.lang.Object resultObject)
                          throws java.io.IOException

write result object. The default implementation writes back single Record results. Subclasses that produce different result types must override this method.

Parameters:

responseStream - response stream

resultObject - result object.

Throws:

java.io.IOException - error writing result

writeErrorResult

protected boolean writeErrorResult(HttpExchange exchange,
                       java.lang.Throwable error,
                       Record inputRecord)
                            throws java.io.IOException

write an error result.

Parameters:

exchange - HTTP exchange

error - the exception causing the error.

inputRecord - the input record.

Returns:

if the connection should be closed after everything is finished.

Throws:

java.io.IOException - error writing the result.

getErrorStatus

protected int getErrorStatus(java.lang.String method,
                 java.lang.String requestUri,
                 java.lang.Throwable ex)

Return a status code for an exception.

See Also:

HTTP_UTILS#getErrorStatus(String, String, Throwable)

getRequestHost

protected java.lang.String getRequestHost(HttpExchange exchange)

Returns the host as defined in the HTTP request.

Parameters:

exchange - http exchange object, contains the request host in the http header

Returns:

the host from the request.