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add java tabs 

Signed-off-by: Hannah Hunter <hannahhunter@microsoft.com>
This commit is contained in:
Hannah Hunter 2023-08-02 15:09:07 -04:00
parent 0211dfef6e
commit 3fdf6d598b
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5
daprdocs/content/en/developing-applications/building-blocks/workflow/workflow-architecture.md
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@ -189,4 +189,7 @@ See the [Reminder usage and execution guarantees section]({{< ref "workflow-arch
- [Workflow overview]({{< ref workflow-overview.md >}})
- [Workflow API reference]({{< ref workflow_api.md >}})
- [Try out the Workflow quickstart]({{< ref workflow-quickstart.md >}})
- [Try out the .NET example](https://github.com/dapr/dotnet-sdk/tree/master/examples/Workflow)
- Try out the following examples:
- [Python](https://github.com/dapr/python-sdk/tree/master/examples/demo_workflow)
- [.NET](https://github.com/dapr/dotnet-sdk/tree/master/examples/Workflow)
- [Java](todo)

376
daprdocs/content/en/developing-applications/building-blocks/workflow/workflow-patterns.md
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@ -25,42 +25,7 @@ While the pattern is simple, there are many complexities hidden in the implement
Dapr Workflow solves these complexities by allowing you to implement the task chaining pattern concisely as a simple function in the programming language of your choice, as shown in the following example.
{{< tabs ".NET" Python >}}
{{% codetab %}}
<!--dotnet-->
```csharp
// Expotential backoff retry policy that survives long outages
var retryOptions = new WorkflowTaskOptions
{
RetryPolicy = new WorkflowRetryPolicy(
firstRetryInterval: TimeSpan.FromMinutes(1),
backoffCoefficient: 2.0,
maxRetryInterval: TimeSpan.FromHours(1),
maxNumberOfAttempts: 10),
};
try
{
var result1 = await context.CallActivityAsync<string>("Step1", wfInput, retryOptions);
var result2 = await context.CallActivityAsync<byte[]>("Step2", result1, retryOptions);
var result3 = await context.CallActivityAsync<long[]>("Step3", result2, retryOptions);
return string.Join(", ", result4);
}
catch (TaskFailedException) // Task failures are surfaced as TaskFailedException
{
// Retries expired - apply custom compensation logic
await context.CallActivityAsync<long[]>("MyCompensation", options: retryOptions);
throw;
}
```
{{% alert title="Note" color="primary" %}}
In the example above, `"Step1"`, `"Step2"`, `"Step3"`, and `"MyCompensation"` represent workflow activities, which are functions in your code that actually implement the steps of the workflow. For brevity, these activity implementations are left out of this example.
{{% /alert %}}
{{% /codetab %}}
{{< tabs Python ".NET" Java >}}
{{% codetab %}}
<!--python-->
@ -103,9 +68,49 @@ def error_handler(ctx, error):
# Do some compensating work
```
{{% alert title="Note" color="primary" %}}
Workflow retry policies will be available in a future version of the Python SDK.
{{% /alert %}}
> **Note** Workflow retry policies will be available in a future version of the Python SDK.
{{% /codetab %}}
{{% codetab %}}
<!--dotnet-->
```csharp
// Expotential backoff retry policy that survives long outages
var retryOptions = new WorkflowTaskOptions
{
RetryPolicy = new WorkflowRetryPolicy(
firstRetryInterval: TimeSpan.FromMinutes(1),
backoffCoefficient: 2.0,
maxRetryInterval: TimeSpan.FromHours(1),
maxNumberOfAttempts: 10),
};
try
{
var result1 = await context.CallActivityAsync<string>("Step1", wfInput, retryOptions);
var result2 = await context.CallActivityAsync<byte[]>("Step2", result1, retryOptions);
var result3 = await context.CallActivityAsync<long[]>("Step3", result2, retryOptions);
return string.Join(", ", result4);
}
catch (TaskFailedException) // Task failures are surfaced as TaskFailedException
{
// Retries expired - apply custom compensation logic
await context.CallActivityAsync<long[]>("MyCompensation", options: retryOptions);
throw;
}
```
> **Note** In the example above, `"Step1"`, `"Step2"`, `"Step3"`, and `"MyCompensation"` represent workflow activities, which are functions in your code that actually implement the steps of the workflow. For brevity, these activity implementations are left out of this example.
{{% /codetab %}}
{{% codetab %}}
<!--java-->
```java
todo
```
{{% /codetab %}}
@ -135,32 +140,7 @@ In addition to the challenges mentioned in [the previous pattern]({{< ref "workf
Dapr Workflows provides a way to express the fan-out/fan-in pattern as a simple function, as shown in the following example:
{{< tabs ".NET" Python >}}
{{% codetab %}}
<!--dotnet-->
```csharp
// Get a list of N work items to process in parallel.
object[] workBatch = await context.CallActivityAsync<object[]>("GetWorkBatch", null);
// Schedule the parallel tasks, but don't wait for them to complete yet.
var parallelTasks = new List<Task<int>>(workBatch.Length);
for (int i = 0; i < workBatch.Length; i++)
{
Task<int> task = context.CallActivityAsync<int>("ProcessWorkItem", workBatch[i]);
parallelTasks.Add(task);
}
// Everything is scheduled. Wait here until all parallel tasks have completed.
await Task.WhenAll(parallelTasks);
// Aggregate all N outputs and publish the result.
int sum = parallelTasks.Sum(t => t.Result);
await context.CallActivityAsync("PostResults", sum);
```
{{% /codetab %}}
{{< tabs Python ".NET" Java >}}
{{% codetab %}}
<!--python-->
@ -202,6 +182,40 @@ def process_results(ctx, final_result: int):
{{% /codetab %}}
{{% codetab %}}
<!--dotnet-->
```csharp
// Get a list of N work items to process in parallel.
object[] workBatch = await context.CallActivityAsync<object[]>("GetWorkBatch", null);
// Schedule the parallel tasks, but don't wait for them to complete yet.
var parallelTasks = new List<Task<int>>(workBatch.Length);
for (int i = 0; i < workBatch.Length; i++)
{
Task<int> task = context.CallActivityAsync<int>("ProcessWorkItem", workBatch[i]);
parallelTasks.Add(task);
}
// Everything is scheduled. Wait here until all parallel tasks have completed.
await Task.WhenAll(parallelTasks);
// Aggregate all N outputs and publish the result.
int sum = parallelTasks.Sum(t => t.Result);
await context.CallActivityAsync("PostResults", sum);
```
{{% /codetab %}}
{{% codetab %}}
<!--java-->
```java
todo
```
{{% /codetab %}}
{{< /tabs >}}
The key takeaways from this example are:
@ -302,48 +316,7 @@ Depending on the business needs, there may be a single monitor or there may be m
Dapr Workflow supports this pattern natively by allowing you to implement _eternal workflows_. Rather than writing infinite while-loops ([which is an anti-pattern]({{< ref "workflow-features-concepts.md#infinite-loops-and-eternal-workflows" >}})), Dapr Workflow exposes a _continue-as-new_ API that workflow authors can use to restart a workflow function from the beginning with a new input.
{{< tabs ".NET" Python >}}
{{% codetab %}}
<!--dotnet-->
```csharp
public override async Task<object> RunAsync(WorkflowContext context, MyEntityState myEntityState)
{
TimeSpan nextSleepInterval;
var status = await context.CallActivityAsync<string>("GetStatus");
if (status == "healthy")
{
myEntityState.IsHealthy = true;
// Check less frequently when in a healthy state
nextSleepInterval = TimeSpan.FromMinutes(60);
}
else
{
if (myEntityState.IsHealthy)
{
myEntityState.IsHealthy = false;
await context.CallActivityAsync("SendAlert", myEntityState);
}
// Check more frequently when in an unhealthy state
nextSleepInterval = TimeSpan.FromMinutes(5);
}
// Put the workflow to sleep until the determined time
await context.CreateTimer(nextSleepInterval);
// Restart from the beginning with the updated state
context.ContinueAsNew(myEntityState);
return null;
}
```
> This example assumes you have a predefined `MyEntityState` class with a boolean `IsHealthy` property.
{{% /codetab %}}
{{< tabs Python ".NET" Java >}}
{{% codetab %}}
<!--python-->
@ -392,6 +365,56 @@ def send_alert(ctx, message: str):
{{% /codetab %}}
{{% codetab %}}
<!--dotnet-->
```csharp
public override async Task<object> RunAsync(WorkflowContext context, MyEntityState myEntityState)
{
TimeSpan nextSleepInterval;
var status = await context.CallActivityAsync<string>("GetStatus");
if (status == "healthy")
{
myEntityState.IsHealthy = true;
// Check less frequently when in a healthy state
nextSleepInterval = TimeSpan.FromMinutes(60);
}
else
{
if (myEntityState.IsHealthy)
{
myEntityState.IsHealthy = false;
await context.CallActivityAsync("SendAlert", myEntityState);
}
// Check more frequently when in an unhealthy state
nextSleepInterval = TimeSpan.FromMinutes(5);
}
// Put the workflow to sleep until the determined time
await context.CreateTimer(nextSleepInterval);
// Restart from the beginning with the updated state
context.ContinueAsNew(myEntityState);
return null;
}
```
> This example assumes you have a predefined `MyEntityState` class with a boolean `IsHealthy` property.
{{% /codetab %}}
{{% codetab %}}
<!--java-->
```java
todo
```
{{% /codetab %}}
{{< /tabs >}}
A workflow implementing the monitor pattern can loop forever or it can terminate itself gracefully by not calling _continue-as-new_.
@ -420,53 +443,7 @@ The following diagram illustrates this flow.
The following example code shows how this pattern can be implemented using Dapr Workflow.
{{< tabs ".NET" Python >}}
{{% codetab %}}
<!--dotnet-->
```csharp
public override async Task<OrderResult> RunAsync(WorkflowContext context, OrderPayload order)
{
// ...(other steps)...
// Require orders over a certain threshold to be approved
if (order.TotalCost > OrderApprovalThreshold)
{
try
{
// Request human approval for this order
await context.CallActivityAsync(nameof(RequestApprovalActivity), order);
// Pause and wait for a human to approve the order
ApprovalResult approvalResult = await context.WaitForExternalEventAsync<ApprovalResult>(
eventName: "ManagerApproval",
timeout: TimeSpan.FromDays(3));
if (approvalResult == ApprovalResult.Rejected)
{
// The order was rejected, end the workflow here
return new OrderResult(Processed: false);
}
}
catch (TaskCanceledException)
{
// An approval timeout results in automatic order cancellation
return new OrderResult(Processed: false);
}
}
// ...(other steps)...
// End the workflow with a success result
return new OrderResult(Processed: true);
}
```
{{% alert title="Note" color="primary" %}}
In the example above, `RequestApprovalActivity` is the name of a workflow activity to invoke and `ApprovalResult` is an enumeration defined by the workflow app. For brevity, these definitions were left out of the example code.
{{% /alert %}}
{{% /codetab %}}
{{< tabs Python ".NET" Java >}}
{{% codetab %}}
<!--python-->
@ -527,26 +504,65 @@ def place_order(_, order: Order) -> None:
{{% /codetab %}}
{{< /tabs >}}
The code that delivers the event to resume the workflow execution is external to the workflow. Workflow events can be delivered to a waiting workflow instance using the [raise event]({{< ref "howto-manage-workflow.md#raise-an-event" >}}) workflow management API, as shown in the following example:
{{< tabs ".NET" Python >}}
{{% codetab %}}
<!--dotnet-->
```csharp
// Raise the workflow event to the waiting workflow
await daprClient.RaiseWorkflowEventAsync(
instanceId: orderId,
workflowComponent: "dapr",
eventName: "ManagerApproval",
eventData: ApprovalResult.Approved);
public override async Task<OrderResult> RunAsync(WorkflowContext context, OrderPayload order)
{
// ...(other steps)...
// Require orders over a certain threshold to be approved
if (order.TotalCost > OrderApprovalThreshold)
{
try
{
// Request human approval for this order
await context.CallActivityAsync(nameof(RequestApprovalActivity), order);
// Pause and wait for a human to approve the order
ApprovalResult approvalResult = await context.WaitForExternalEventAsync<ApprovalResult>(
eventName: "ManagerApproval",
timeout: TimeSpan.FromDays(3));
if (approvalResult == ApprovalResult.Rejected)
{
// The order was rejected, end the workflow here
return new OrderResult(Processed: false);
}
}
catch (TaskCanceledException)
{
// An approval timeout results in automatic order cancellation
return new OrderResult(Processed: false);
}
}
// ...(other steps)...
// End the workflow with a success result
return new OrderResult(Processed: true);
}
```
> **Note** In the example above, `RequestApprovalActivity` is the name of a workflow activity to invoke and `ApprovalResult` is an enumeration defined by the workflow app. For brevity, these definitions were left out of the example code.
{{% /codetab %}}
{{% codetab %}}
<!--java-->
```java
todo
```
{{% /codetab %}}
{{< /tabs >}}
The code that delivers the event to resume the workflow execution is external to the workflow. Workflow events can be delivered to a waiting workflow instance using the [raise event]({{< ref "howto-manage-workflow.md#raise-an-event" >}}) workflow management API, as shown in the following example:
{{< tabs Python ".NET" Java >}}
{{% codetab %}}
<!--python-->
@ -564,6 +580,29 @@ with DaprClient() as d:
{{% /codetab %}}
{{% codetab %}}
<!--dotnet-->
```csharp
// Raise the workflow event to the waiting workflow
await daprClient.RaiseWorkflowEventAsync(
instanceId: orderId,
workflowComponent: "dapr",
eventName: "ManagerApproval",
eventData: ApprovalResult.Approved);
```
{{% /codetab %}}
{{% codetab %}}
<!--java-->
```java
todo
```
{{% /codetab %}}
{{< /tabs >}}
External events don't have to be directly triggered by humans. They can also be triggered by other systems. For example, a workflow may need to pause and wait for a payment to be received. In this case, a payment system might publish an event to a pub/sub topic on receipt of a payment, and a listener on that topic can raise an event to the workflow using the raise event workflow API.
@ -577,4 +616,7 @@ External events don't have to be directly triggered by humans. They can also be
- [Try out Dapr Workflows using the quickstart]({{< ref workflow-quickstart.md >}})
- [Workflow overview]({{< ref workflow-overview.md >}})
- [Workflow API reference]({{< ref workflow_api.md >}})
- [Try out the .NET example](https://github.com/dapr/dotnet-sdk/tree/master/examples/Workflow)
- Try out the following examples:
- [Python](https://github.com/dapr/python-sdk/tree/master/examples/demo_workflow)
- [.NET](https://github.com/dapr/dotnet-sdk/tree/master/examples/Workflow)
- [Java](todo)