# Interface IWorkflowExternalParametersProvider

OptimaJet.Workflow.Core.Runtime.IWorkflowExternalParametersProvider

Provides access to workflow external parameters for a specific process instance.

Namespace: [OptimaJet.Workflow.Core.Runtime](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Runtime/)

```csharp
public interface IWorkflowExternalParametersProvider
```

## Type Hierarchy

-   IWorkflowExternalParametersProvider Current type
    -   Implementing types
        -   [AggregatingExternalParametersProvider](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Runtime/AggregatingExternalParametersProvider/)
        -   [EmptyWorkflowExternalParametersProvider](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Runtime/EmptyWorkflowExternalParametersProvider/)

## Methods

`Task<object> GetExternalParameterAsync(string parameterName, ProcessInstance processInstance)` 

Gets the value of the named external parameter asynchronously.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameterName` | `String` | The external parameter name. |
| `processInstance` | `ProcessInstance` | The workflow process instance for which the parameter is requested. |

### Returns

| Type | Description |
| --- | --- |
| `Task<Object>` | The asynchronous result containing the external parameter value. |

### Remarks

The runtime calls this method when [IWorkflowExternalParametersProvider.IsGetExternalParameterAsync(string, string, ProcessInstance)](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Runtime/IWorkflowExternalParametersProvider/) is [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) for the same parameter and scheme combination.

`object GetExternalParameter(string parameterName, ProcessInstance processInstance)` 

Gets the value of the named external parameter synchronously.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameterName` | `String` | The external parameter name. |
| `processInstance` | `ProcessInstance` | The workflow process instance for which the parameter is requested. |

### Returns

| Type | Description |
| --- | --- |
| `Object` | The external parameter value. |

### Remarks

The runtime calls this method when [IWorkflowExternalParametersProvider.IsGetExternalParameterAsync(string, string, ProcessInstance)](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Runtime/IWorkflowExternalParametersProvider/) is [false](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) for the same parameter and scheme combination.

`Task SetExternalParameterAsync(string parameterName, object parameterValue, ProcessInstance processInstance)` 

Writes the named external parameter value asynchronously.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameterName` | `String` | The external parameter name. |
| `parameterValue` | `Object` | The value to write. |
| `processInstance` | `ProcessInstance` | The workflow process instance for which the parameter is updated. |

### Returns

| Type | Description |
| --- | --- |
| `Task` | A task that completes when the parameter value is written. |

### Remarks

The runtime calls this method when [IWorkflowExternalParametersProvider.IsSetExternalParameterAsync(string, string, ProcessInstance)](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Runtime/IWorkflowExternalParametersProvider/) is [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) for the same parameter and scheme combination.

`void SetExternalParameter(string parameterName, object parameterValue, ProcessInstance processInstance)` 

Writes the named external parameter value synchronously.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameterName` | `String` | The external parameter name. |
| `parameterValue` | `Object` | The value to write. |
| `processInstance` | `ProcessInstance` | The workflow process instance for which the parameter is updated. |

### Remarks

The runtime calls this method when [IWorkflowExternalParametersProvider.IsSetExternalParameterAsync(string, string, ProcessInstance)](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Runtime/IWorkflowExternalParametersProvider/) is [false](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) for the same parameter and scheme combination.

`bool IsGetExternalParameterAsync(string parameterName, string schemeCode, ProcessInstance processInstance)` 

Checks whether asynchronous external-parameter reads are supported for the named parameter.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameterName` | `String` | The external parameter name. |
| `schemeCode` | `String` | The scheme code for provider selection. |
| `processInstance` | `ProcessInstance` | The workflow process instance used for context checks. |

### Returns

| Type | Description |
| --- | --- |
| `Boolean` | [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) if [IWorkflowExternalParametersProvider.GetExternalParameterAsync(string, ProcessInstance)](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Runtime/IWorkflowExternalParametersProvider/) is supported. |

`bool IsSetExternalParameterAsync(string parameterName, string schemeCode, ProcessInstance processInstance)` 

Checks whether asynchronous external-parameter writes are supported for the named parameter.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameterName` | `String` | The external parameter name. |
| `schemeCode` | `String` | The scheme code for provider selection. |
| `processInstance` | `ProcessInstance` | The workflow process instance used for context checks. |

### Returns

| Type | Description |
| --- | --- |
| `Boolean` | [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) if [IWorkflowExternalParametersProvider.SetExternalParameterAsync(string, object, ProcessInstance)](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Runtime/IWorkflowExternalParametersProvider/) is supported. |

`bool HasExternalParameter(string parameterName, string schemeCode, ProcessInstance processInstance)` 

Checks whether the named external parameter exists in this provider for the scheme and process context.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameterName` | `String` | The external parameter name. |
| `schemeCode` | `String` | The scheme code for provider selection. |
| `processInstance` | `ProcessInstance` | The workflow process instance used for context checks. |

### Returns

| Type | Description |
| --- | --- |
| `Boolean` | [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) if the parameter is recognized by the provider. |

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