/
HelloSaga.java
332 lines (289 loc) · 12.5 KB
/
HelloSaga.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
/*
* Copyright (c) 2020 Temporal Technologies, Inc. All Rights Reserved
*
* Copyright 2012-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Modifications copyright (C) 2017 Uber Technologies, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"). You may not
* use this file except in compliance with the License. A copy of the License is
* located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
package io.temporal.samples.hello;
import io.temporal.activity.ActivityInterface;
import io.temporal.activity.ActivityMethod;
import io.temporal.activity.ActivityOptions;
import io.temporal.client.WorkflowClient;
import io.temporal.client.WorkflowOptions;
import io.temporal.serviceclient.WorkflowServiceStubs;
import io.temporal.worker.Worker;
import io.temporal.worker.WorkerFactory;
import io.temporal.workflow.Async;
import io.temporal.workflow.Promise;
import io.temporal.workflow.Saga;
import io.temporal.workflow.Workflow;
import io.temporal.workflow.WorkflowInterface;
import io.temporal.workflow.WorkflowMethod;
import java.time.Duration;
/**
* Sample Temporal workflow that demonstrates the workflow compensation capability.
*
* <p>Compensation deals with undoing or reversing work which has already successfully completed.
* (also called SAGA). Temporal includes very powerful support for compensation which is showedcased
* in this example.
*
* @see io.temporal.samples.bookingsaga.TripBookingSaga for another SAGA example.
*/
public class HelloSaga {
// Define the task queue name
static final String TASK_QUEUE = "HelloSagaTaskQueue";
// Define the workflow unique id
static final String WORKFLOW_ID = "HelloSagaTaskWorkflow";
/**
* Define the child workflow interface. It must contain one method annotated with @WorkflowMethod
*
* @see io.temporal.workflow.WorkflowInterface
* @see io.temporal.workflow.WorkflowMethod
*/
@WorkflowInterface
public interface ChildWorkflowOperation {
/**
* Define the child workflow method. This method is executed when the child workflow is started.
* The child workflow completes when the workflow method finishes execution.
*/
@WorkflowMethod
void execute(int amount);
}
// Define the child workflow implementation. It implements the execute workflow method
public static class ChildWorkflowOperationImpl implements ChildWorkflowOperation {
/*
* Define the ActivityOperation stub. Activity stubs are proxies for activity invocations that
* are executed outside of the workflow thread on the activity worker, that can be on a
* different host. Temporal is going to dispatch the activity results back to the workflow and
* unblock the stub as soon as activity is completed on the activity worker.
*
* <p>In the {@link ActivityOptions} definition the "setStartToCloseTimeout" option sets the
* maximum time of a single Activity execution attempt. For this example it is set to 10
* seconds.
*/
ActivityOperation activity =
Workflow.newActivityStub(
ActivityOperation.class,
ActivityOptions.newBuilder().setStartToCloseTimeout(Duration.ofSeconds(10)).build());
@Override
public void execute(int amount) {
activity.execute(amount);
}
}
/**
* Define the child workflow compensation interface. It must contain one method annotated
* with @WorkflowMethod
*
* @see io.temporal.workflow.WorkflowInterface
* @see io.temporal.workflow.WorkflowMethod
*/
@WorkflowInterface
public interface ChildWorkflowCompensation {
/**
* Define the child workflow compensation method. This method is executed when the child
* workflow is started. The child workflow completes when the workflow method finishes
* execution.
*/
@WorkflowMethod
void compensate(int amount);
}
// Define the child workflow compensation implementation. It implements the compensate child
// workflow method
public static class ChildWorkflowCompensationImpl implements ChildWorkflowCompensation {
/*
* Define the ActivityOperation stub. Activity stubs are proxies for activity invocations that
* are executed outside of the workflow thread on the activity worker, that can be on a
* different host. Temporal is going to dispatch activity results back to the workflow and
* unblock the stub as soon as activity is completed on the activity worker.
*
* <p>In the {@link ActivityOptions} definition the"setStartToCloseTimeout" option sets the
* maximum time of a single Activity execution attempt. For this example it is set to 10
* seconds.
*/
ActivityOperation activity =
Workflow.newActivityStub(
ActivityOperation.class,
ActivityOptions.newBuilder().setStartToCloseTimeout(Duration.ofSeconds(10)).build());
@Override
public void compensate(int amount) {
activity.compensate(amount);
}
}
/**
* This is the Activity Definition's Interface. Activities are building blocks of any Temporal
* Workflow and contain any business logic that could perform long running computation, network
* calls, etc.
*
* <p>Annotating Activity Definition methods with @ActivityMethod is optional.
*
* @see io.temporal.activity.ActivityInterface
* @see io.temporal.activity.ActivityMethod
*/
@ActivityInterface
public interface ActivityOperation {
@ActivityMethod
void execute(int amount);
@ActivityMethod
void compensate(int amount);
}
/**
* Implementation of the workflow activity interface. It overwrites the defined execute and
* compensate activity methods.
*/
public static class ActivityOperationImpl implements ActivityOperation {
@Override
public void execute(int amount) {
System.out.println("ActivityOperationImpl.execute() is called with amount " + amount);
}
@Override
public void compensate(int amount) {
System.out.println("ActivityCompensationImpl.compensate() is called with amount " + amount);
}
}
/**
* Define the main workflow interface. It must contain one method annotated with @WorkflowMethod
*
* @see io.temporal.workflow.WorkflowInterface
* @see io.temporal.workflow.WorkflowMethod
*/
@WorkflowInterface
public interface SagaWorkflow {
/**
* This is the method that is executed when the Workflow Execution is started. The Workflow
* Execution completes when this method finishes execution.
*/
@WorkflowMethod
void execute();
}
// Define the main workflow implementation. It implements the execute workflow method
public static class SagaWorkflowImpl implements SagaWorkflow {
/*
* Define the ActivityOperation stub. Activity stubs are proxies for activity invocations that
* are executed outside of the workflow thread on the activity worker, that can be on a
* different host. Temporal is going to dispatch activity results back to the workflow and
* unblock the stub as soon as activity is completed on the activity worker.
*
* <p>In the {@link ActivityOptions} definition the "setStartToCloseTimeout" option sets the
* maximum time of a single Activity execution attempt. For this example it is set to 2 seconds.
*/
ActivityOperation activity =
Workflow.newActivityStub(
ActivityOperation.class,
ActivityOptions.newBuilder().setStartToCloseTimeout(Duration.ofSeconds(2)).build());
@Override
public void execute() {
// {@link io.temporal.workflow.Saga} implements the logic to perform compensation operations
Saga saga = new Saga(new Saga.Options.Builder().setParallelCompensation(false).build());
try {
/*
* First we show how to compensate sync child workflow invocations. We first create a child
* workflow stub and execute its "execute" method. Then we create a stub of the child
* compensation workflow and register it with Saga. At this point this compensation workflow
* is not invoked. It is invoked explicitly when we actually want to invoke compensation
* (via saga.compensate()).
*/
ChildWorkflowOperation op1 = Workflow.newChildWorkflowStub(ChildWorkflowOperation.class);
op1.execute(10);
ChildWorkflowCompensation c1 =
Workflow.newChildWorkflowStub(ChildWorkflowCompensation.class);
saga.addCompensation(c1::compensate, -10);
/*
* Now we show compensation of workflow activities which are invoked asynchronously. We
* invoke the activity "execute" method async. Then we register its "compensate" method as
* the compensation method for it.
*
* <p>Again note that the compensation of this activity again is only explicitly invoked
* (via saga.compensate()).
*/
Promise<Void> result = Async.procedure(activity::execute, 20);
saga.addCompensation(activity::compensate, -20);
// get the result of the activity (blocking)
result.get();
/*
* You can also supply an arbitrary lambda expression as a saga
* compensation function.
* Note that this compensation function is not associated with a child workflow
* method or an activity method. It is associated with the currently executing
* workflow method.
*
* Also note that here in this example we use System.out in the main workflow logic.
* In production make sure to use Workflow.getLogger to log messages from workflow code.
*/
saga.addCompensation(
() -> System.out.println("Other compensation logic in main workflow."));
/*
* Here we throw a runtime exception on purpose to showcase
* how to trigger compensation in case of an exception.
* Note that compensation can be also triggered
* without a specific exception being thrown. You can built in
* compensation to be part of your core workflow business requirements,
* meaning it can be triggered as part of your business logic.
*/
throw new RuntimeException("some error");
} catch (Exception e) {
// we catch our exception and trigger workflow compensation
saga.compensate();
}
}
}
/**
* With our Workflow and Activities defined, we can now start execution. The main method starts
* the worker and then the workflow.
*/
public static void main(String[] args) {
// Define the workflow service.
WorkflowServiceStubs service = WorkflowServiceStubs.newLocalServiceStubs();
/*
* Get a Workflow service client which can be used to start, Signal, and Query Workflow Executions.
*/
WorkflowClient client = WorkflowClient.newInstance(service);
/*
* Define the workflow factory. It is used to create workflow workers for a specific task queue.
*/
WorkerFactory factory = WorkerFactory.newInstance(client);
/*
* Define the workflow worker. Workflow workers listen to a defined task queue and process
* workflows and activities.
*/
Worker worker = factory.newWorker(TASK_QUEUE);
/*
* Register our workflow implementations with the worker. Since workflows are stateful in nature,
* we need to register our workflow types.
*/
worker.registerWorkflowImplementationTypes(
HelloSaga.SagaWorkflowImpl.class,
HelloSaga.ChildWorkflowOperationImpl.class,
HelloSaga.ChildWorkflowCompensationImpl.class);
/*
* Register our Activity Types with the Worker. Since Activities are stateless and thread-safe,
* the Activity Type is a shared instance.
*/
worker.registerActivitiesImplementations(new ActivityOperationImpl());
/*
* Start all the workers registered for a specific task queue.
* The started workers then start polling for workflows and activities.
*/
factory.start();
// Create our workflow options
WorkflowOptions workflowOptions =
WorkflowOptions.newBuilder().setWorkflowId(WORKFLOW_ID).setTaskQueue(TASK_QUEUE).build();
// Create the workflow client stub. It is used to start our workflow execution.
HelloSaga.SagaWorkflow workflow =
client.newWorkflowStub(HelloSaga.SagaWorkflow.class, workflowOptions);
// Execute our workflow
workflow.execute();
System.exit(0);
}
}