Use client libraries to execute a workflow. Polls the workflow's execution using exponential backoff until the execution terminates and then prints the results.
Explore further
For detailed documentation that includes this code sample, see the following:
Code sample
Java
Before trying this sample, follow the Java setup instructions in the Workflows quickstart using client libraries . For more information, see the Workflows Java API reference documentation .
To authenticate to Workflows, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .
// Imports the Google Cloud client library
import
com.google.cloud.workflows.executions.v1. CreateExecutionRequest
;
import
com.google.cloud.workflows.executions.v1. Execution
;
import
com.google.cloud.workflows.executions.v1. ExecutionsClient
;
import
com.google.cloud.workflows.executions.v1. WorkflowName
;
import
java.io.IOException
;
import
java.util.concurrent.ExecutionException
;
public
class
WorkflowsQuickstart
{
private
static
final
String
PROJECT
=
System
.
getenv
(
"GOOGLE_CLOUD_PROJECT"
);
private
static
final
String
LOCATION
=
System
.
getenv
().
getOrDefault
(
"LOCATION"
,
"us-central1"
);
private
static
final
String
WORKFLOW
=
System
.
getenv
().
getOrDefault
(
"WORKFLOW"
,
"myFirstWorkflow"
);
public
static
void
main
(
String
...
args
)
throws
IOException
,
InterruptedException
,
ExecutionException
{
if
(
PROJECT
==
null
)
{
throw
new
IllegalArgumentException
(
"Environment variable 'GOOGLE_CLOUD_PROJECT' is required to run this quickstart."
);
}
workflowsQuickstart
(
PROJECT
,
LOCATION
,
WORKFLOW
);
}
private
static
volatile
boolean
finished
;
public
static
void
workflowsQuickstart
(
String
projectId
,
String
location
,
String
workflow
)
throws
IOException
,
InterruptedException
,
ExecutionException
{
// Initialize client that will be used to send requests. This client only needs
// to be created once, and can be reused for multiple requests. After completing all of your
// requests, call the "close" method on the client to safely clean up any remaining background
// resources.
try
(
ExecutionsClient
executionsClient
=
ExecutionsClient
.
create
())
{
// Construct the fully qualified location path.
WorkflowName
parent
=
WorkflowName
.
of
(
projectId
,
location
,
workflow
);
// Creates the execution object.
CreateExecutionRequest
request
=
CreateExecutionRequest
.
newBuilder
()
.
setParent
(
parent
.
toString
())
.
setExecution
(
Execution
.
newBuilder
().
build
())
.
build
();
Execution
response
=
executionsClient
.
createExecution
(
request
);
String
executionName
=
response
.
getName
();
System
.
out
.
printf
(
"Created execution: %s%n"
,
executionName
);
long
backoffTime
=
0
;
long
backoffDelay
=
1_000
;
// Start wait with delay of 1,000 ms
final
long
backoffTimeout
=
10
*
60
*
1_000
;
// Time out at 10 minutes
System
.
out
.
println
(
"Poll for results..."
);
// Wait for execution to finish, then print results.
while
(
!
finished
&&
backoffTime
<
backoffTimeout
)
{
Execution
execution
=
executionsClient
.
getExecution
(
executionName
);
finished
=
execution
.
getState
()
!=
Execution
.
State
.
ACTIVE
;
// If we haven't seen the results yet, wait.
if
(
!
finished
)
{
System
.
out
.
println
(
"- Waiting for results"
);
Thread
.
sleep
(
backoffDelay
);
backoffTime
+=
backoffDelay
;
backoffDelay
*=
2
;
// Double the delay to provide exponential backoff.
}
else
{
System
.
out
.
println
(
"Execution finished with state: "
+
execution
.
getState
().
name
());
System
.
out
.
println
(
"Execution results: "
+
execution
.
getResult
());
}
}
}
}
}
Node.js
Before trying this sample, follow the Node.js setup instructions in the Workflows quickstart using client libraries . For more information, see the Workflows Node.js API reference documentation .
To authenticate to Workflows, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .
const
{
ExecutionsClient
}
=
require
(
'@google-cloud/workflows'
);
const
client
=
new
ExecutionsClient
();
/**
* TODO(developer): Uncomment these variables before running the sample.
*/
//
const
projectId
=
'my-project'
;
//
const
location
=
'us-central1'
;
//
const
workflow
=
'myFirstWorkflow'
;
//
const
searchTerm
=
''
;
/**
* Executes a Workflow and waits for the results with exponential backoff.
* @param {string} projectId The Google Cloud Project containing the workflow
* @param {string} location The workflow location
* @param {string} workflow The workflow name
* @param {string} searchTerm Optional search term to pass to the Workflow as a runtime argument
*/
async
function
executeWorkflow
(
projectId
,
location
,
workflow
,
searchTerm
)
{
/**
* Sleeps the process N number of milliseconds.
* @param {Number} ms The number of milliseconds to sleep.
*/
function
sleep
(
ms
)
{
return
new
Promise
(
resolve
=
>
{
setTimeout
(
resolve
,
ms
);
}
);
}
const
runtimeArgs
=
searchTerm
?
{
searchTerm
:
searchTerm
}
:
{}
;
//
Execute
workflow
try
{
const
createExecutionRes
=
await
client
.
createExecution
(
{
parent
:
client
.
workflowPath
(
projectId
,
location
,
workflow
),
execution
:
{
//
Runtime
arguments
can
be
passed
as
a
JSON
string
argument
:
JSON
.
stringify
(
runtimeArgs
),
}
,
}
);
const
executionName
=
createExecutionRes
[
0
]
.
name
;
console
.
log
(
`
Created
execution
:
${
executionName
}`
);
//
Wait
for
execution
to
finish
,
then
print
results
.
let
executionFinished
=
false
;
let
backoffDelay
=
1000
;
//
Start
wait
with
delay
of
1
,
000
ms
console
.
log
(
'Poll every second for result...'
);
while
(
!
executionFinished
)
{
const
[
execution
]
=
await
client
.
getExecution
(
{
name
:
executionName
,
}
);
executionFinished
=
execution
.
state
!==
'ACTIVE'
;
//
If
we
haven
't seen the result yet, wait a second.
if (!executionFinished) {
console.log('
-
Waiting
for
results
...
'
);
await
sleep
(
backoffDelay
);
backoffDelay
*=
2
;
//
Double
the
delay
to
provide
exponential
backoff
.
}
else
{
console
.
log
(
`
Execution
finished
with
state
:
${
execution
.
state
}`
);
console
.
log
(
execution
.
result
);
return
execution
.
result
;
}
}
}
catch
(
e
)
{
console
.
error
(
`
Error
executing
workflow
:
${
e
}`
);
}
}
executeWorkflow
(
projectId
,
location
,
workflowName
,
searchTerm
).
catch
(
err
=
>
{
console
.
error
(
err
.
message
);
process
.
exitCode
=
1
;
}
);
Node.js
Before trying this sample, follow the Node.js setup instructions in the Workflows quickstart using client libraries . For more information, see the Workflows Node.js API reference documentation .
To authenticate to Workflows, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .
import
{
ExecutionsClient
}
from
'@google-cloud/workflows'
;
const
client
:
ExecutionsClient
=
new
ExecutionsClient
();
/**
*
TODO
(
developer
):
Uncomment
these
variables
before
running
the
sample
.
*/
//
const
projectId
=
'my-project'
;
//
const
location
=
'us-central1'
;
//
const
workflow
=
'myFirstWorkflow'
;
//
const
searchTerm
=
''
;
/**
*
Executes
a
Workflow
and
waits
for
the
results
with
exponential
backoff
.
*
@param
{
string
}
projectId
The
Google
Cloud
Project
containing
the
workflow
*
@param
{
string
}
location
The
workflow
location
*
@param
{
string
}
workflow
The
workflow
name
*
@param
{
string
}
searchTerm
Optional
search
term
to
pass
to
the
Workflow
as
a
runtime
argument
*/
async
function
executeWorkflow
(
projectId
:
string
,
location
:
string
,
workflow
:
string
,
searchTerm
:
string
)
{
/**
*
Sleeps
the
process
N
number
of
milliseconds
.
*
@param
{
Number
}
ms
The
number
of
milliseconds
to
sleep
.
*/
function
sleep
(
ms
:
number
):
Promise<unknown>
{
return
new
Promise
(
resolve
=
> {
setTimeout
(
resolve
,
ms
);
});
}
const
runtimeArgs
=
searchTerm
?
{
searchTerm
:
searchTerm
}
:
{};
//
Execute
workflow
try
{
const
createExecutionRes
=
await
client
.
createExecution
({
parent
:
client
.
workflowPath
(
projectId
,
location
,
workflow
),
execution
:
{
//
Runtime
arguments
can
be
passed
as
a
JSON
string
argument
:
JSON
.
stringify
(
runtimeArgs
),
},
});
const
executionName
=
createExecutionRes
[
0
]
.
name
;
console
.
log
(
`
Created
execution
:
$
{
executionName
}
`
);
//
Wait
for
execution
to
finish
,
then
print
results
.
let
executionFinished
=
false
;
let
backoffDelay
=
1000
;
//
Start
wait
with
delay
of
1
,
000
ms
console
.
log
(
'Poll every second for result...'
);
while
(
!
executionFinished
)
{
const
[
execution
]
=
await
client
.
getExecution
({
name
:
executionName
,
});
executionFinished
=
execution
.
state
!==
'ACTIVE'
;
//
If
we
haven
't seen the result yet, wait a second.
if
(
!
executionFinished
)
{
console
.
log
(
'- Waiting for results...'
);
await
sleep
(
backoffDelay
);
backoffDelay
*=
2
;
//
Double
the
delay
to
provide
exponential
backoff
.
}
else
{
console
.
log
(
`
Execution
finished
with
state
:
$
{
execution
.
state
}
`
);
console
.
log
(
execution
.
result
);
return
execution
.
result
;
}
}
}
catch
(
e
)
{
console
.
error
(
`
Error
executing
workflow
:
$
{
e
}
`
);
}
}
executeWorkflow
(
projectId
,
location
,
workflowName
,
searchTerm
)
.
catch
(
(
err
:
Error
)
=
> {
console
.
error
(
err
.
message
);
process
.
exitCode
=
1
;
}
);
Python
Before trying this sample, follow the Python setup instructions in the Workflows quickstart using client libraries . For more information, see the Workflows Python API reference documentation .
To authenticate to Workflows, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .
import
time
from
google.cloud
import
workflows
_v1 from
google.cloud.workflows
import
executions_v1
from
google.cloud.workflows.executions_v1.types
import
executions
# TODO(developer): Update and uncomment the following lines.
# project_id = "MY_PROJECT_ID"
# location = "MY_LOCATION" # For example: us-central1
# workflow_id = "MY_WORKFLOW_ID" # For example: myFirstWorkflow
# Initialize API clients.
execution_client
=
executions_v1
.
ExecutionsClient
()
workflows_client
=
workflows_v1
.
WorkflowsClient
()
# Construct the fully qualified location path.
parent
=
workflows_client
.
workflow_path
(
project_id
,
location
,
workflow_id
)
# Execute the workflow.
response
=
execution_client
.
create_execution
(
request
=
{
"parent"
:
parent
})
print
(
f
"Created execution:
{
response
.
name
}
"
)
# Wait for execution to finish, then print results.
execution_finished
=
False
backoff_delay
=
1
# Start wait with delay of 1 second.
print
(
"Poll for result..."
)
while
not
execution_finished
:
execution
=
execution_client
.
get_execution
(
request
=
{
"name"
:
response
.
name
}
)
execution_finished
=
execution
.
state
!=
executions
.
Execution
.
State
.
ACTIVE
# If we haven't seen the result yet, keep waiting.
if
not
execution_finished
:
print
(
"- Waiting for results..."
)
time
.
sleep
(
backoff_delay
)
# Double the delay to provide exponential backoff.
backoff_delay
*=
2
else
:
print
(
f
"Execution finished with state:
{
execution
.
state
.
name
}
"
)
print
(
f
"Execution results:
{
execution
.
result
}
"
)
What's next
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