Package org.chenile.cloudedgeswitch.interceptor

Class CloudEdgeSwitch

java.lang.Object

org.chenile.core.interceptors.BaseChenileInterceptor

org.chenile.cloudedgeswitch.interceptor.CloudEdgeSwitch

All Implemented Interfaces:

Command<ChenileExchange>

public class CloudEdgeSwitch
extends BaseChenileInterceptor

This interceptor, if configured, acts like an edge switch for a service i.e. it turns a service from a cloud service into an edge service.

This switch looks for a property called remoteUrl. If the remote Url is not configured then it assumes that the service is running in the cloud. For the cloud it merely passes control to the service and publishes a message upon successful execution so that all edges can update themselves

If the remoteUrl is configured then it switches the functionality to the "edge" mode.

The edge service logic is as follows:
* If the cloud service is detected and can be successfully invoked synchronously via HTTP, then the edge service is a "forward only" service. Else it is a "store and forward service"

The local service call is bypassed completely at the edge. The Switch attempts to call the same service but hosted in the cloud. The remote url is the cloud location of the service. If the cloud call is successful, then this effectively acts as if the edge service is a traffic cop merely directing all the incoming traffic to the cloud and returning the result of the cloud service call. This is the 'forward only' functionality

If the call fails due to a problem with the connection (we check this explicitly) then the "store and forward" part of the logic kicks in. In this case the local service is called. If successful, the result of the local service call is returned with a warning stating that the transaction succeeded but it is done locally due to network failure.

Then a message is forwarded to the cloud via MQ-TT. This message, when received, will cause the cloud service to update itself and also notify all the edges (except the edge that notified the cloud in the first place)

Field Summary

Fields

Modifier and Type	Field	Description
private String	cloudClientID
private HeaderCopier	headerCopier
(package private) org.slf4j.Logger	logger
private MqttPublisher	mqttPublisher
(package private) ObjectWriter	objectWriter
private ProxyBuilder	proxyBuilder
private String	remoteUrl

Constructor Summary

Constructors

Constructor	Description
CloudEdgeSwitch()

Method Summary

Modifier and Type	Method	Description
private Map<String,Object>	addMqttTargetHeaderIfRequired(ChenileExchange exchange)	If this message came from MQTT then the original source must not be receiving this message since that would create duplicates.
protected boolean	bypassInterception(ChenileExchange exchange)	Over-ride this to bypass interception in special circumstances
private boolean	callCloud(ChenileExchange exchange)	Switch to cloud proxy and invoke it via http
private boolean	callEdge(ChenileExchange exchange, Object serviceReference, ChainContext.SavePoint savePoint)
private void	enhanceWarnings(ErrorNumException exception, ChenileExchange exchange)
void	execute(ChenileExchange exchange)	If this method is over-ridden, make sure that you call doContinue unless you want to end the chain here! This is very important.
private Object	getRemoteProxy(ChenileExchange exchange)
private void	handleCloud(ChenileExchange exchange)	In the cloud, execute the actual service Upon successful return, send a message to MQTT topic
private void	handleEdge(ChenileExchange exchange)	In the edge, we will delegate the control to the cloud.
private void	handleHttp(ChenileExchange exchange)
private void	handleMqtt(ChenileExchange exchange)	In MQTT, if the message comes to the edge, call the service as usual If it is the cloud, handle it like you do HTTP messages
private void	publishMessage(ChenileExchange exchange, Map<String,Object> headers)
void	setCloudClientId(String cloudClientID)
void	setRemoteUrl(String remoteUrl)
private void	switchServiceReference(Object ref, ChenileExchange exchange)
private String	toJson(Object payload)

Methods inherited from class org.chenile.core.interceptors.BaseChenileInterceptor

doContinue, doPostProcessing, doPreProcessing, getExtensionByAnnotation, getExtensionByAnnotation, resumeFromSavedPoint, savePoint

Methods inherited from class java.lang.Object

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

Field Details

logger

org.slf4j.Logger logger

remoteUrl

private String remoteUrl

cloudClientID

private String cloudClientID

mqttPublisher

@Autowired
private MqttPublisher mqttPublisher

proxyBuilder

@Autowired
private ProxyBuilder proxyBuilder

headerCopier

@Autowired
@Qualifier("populateContextContainer")
private HeaderCopier headerCopier

objectWriter

ObjectWriter objectWriter

Constructor Details

CloudEdgeSwitch

public CloudEdgeSwitch()

Method Details

setRemoteUrl

public void setRemoteUrl(String remoteUrl)

setCloudClientId

public void setCloudClientId(String cloudClientID)

execute

public void execute(ChenileExchange exchange)
             throws Exception

Description copied from class: BaseChenileInterceptor

If this method is over-ridden, make sure that you call doContinue unless you want to end the chain here! This is very important. Also, if there is an exception downstream it needs to be handled here after a call to BaseChenileInterceptor.doContinue(ChenileExchange) In most cases, you will do fine overriding BaseChenileInterceptor.doPreProcessing(ChenileExchange) and BaseChenileInterceptor.doPostProcessing(ChenileExchange)

Specified by:

execute in interface Command<ChenileExchange>

Overrides:

execute in class BaseChenileInterceptor

Throws:

Exception

handleMqtt

private void handleMqtt(ChenileExchange exchange)
                 throws Exception

In MQTT, if the message comes to the edge, call the service as usual If it is the cloud, handle it like you do HTTP messages

Parameters:

exchange - the chenile exchange

Throws:

Exception - in case of any problem downstream

handleHttp

private void handleHttp(ChenileExchange exchange)
                 throws Exception

Throws:

Exception

handleEdge

private void handleEdge(ChenileExchange exchange)
                 throws Exception

In the edge, we will delegate the control to the cloud.

Parameters:

exchange - the chenile exchange

Throws:

Exception

callEdge

private boolean callEdge(ChenileExchange exchange,
 Object serviceReference,
 ChainContext.SavePoint savePoint)

callCloud

private boolean callCloud(ChenileExchange exchange)

Switch to cloud proxy and invoke it via http

Parameters:

exchange - - the chenile exchange

Returns:

true if cloud invocation could be done. false if connectivity is a problem

handleCloud

private void handleCloud(ChenileExchange exchange)
                  throws Exception

In the cloud, execute the actual service Upon successful return, send a message to MQTT topic

Parameters:

exchange - the Chenile exchange

Throws:

Exception

addMqttTargetHeaderIfRequired

private Map<String,Object> addMqttTargetHeaderIfRequired(ChenileExchange exchange)

If this message came from MQTT then the original source must not be receiving this message since that would create duplicates. Hence, we will create a target header telling the original source to not update itself again.

Parameters:

exchange - the chenile exchange

Returns:

the headers map

publishMessage

private void publishMessage(ChenileExchange exchange,
 Map<String,Object> headers)

toJson

private String toJson(Object payload)
               throws Exception

Throws:

Exception

enhanceWarnings

private void enhanceWarnings(ErrorNumException exception,
 ChenileExchange exchange)

switchServiceReference

private void switchServiceReference(Object ref,
 ChenileExchange exchange)

getRemoteProxy

private Object getRemoteProxy(ChenileExchange exchange)

bypassInterception

protected boolean bypassInterception(ChenileExchange exchange)

Description copied from class: BaseChenileInterceptor

Over-ride this to bypass interception in special circumstances

Overrides:

bypassInterception in class BaseChenileInterceptor

Returns: