Add a new name resolution method: structuredformat doc

daprdocs/content/en/reference/components-reference/supported-name-resolution/nr-structuredformat.md

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+---
+type: docs
+title: "StructuredFormat"
+linkTitle: "StructuredFormat"
+description: Detailed information on the StructuredFormat name resolution component
+---
+
+
+The **Structured Format** name resolver enables you to explicitly define service instances using structured configuration in **JSON or YAML**, either as inline strings or external files. It is designed for scenarios where service topology is **static and known in advance**, such as:
+
+- Local development and testing
+- Integration or end-to-end test environments
+- Edge deployments
+
+## Configuration format
+
+Name resolution is configured via the [Dapr Configuration]({{< ref configuration-overview.md >}}).
+
+```yaml
+apiVersion: dapr.io/v1alpha1
+kind: Configuration
+metadata:
+  name: appconfig
+spec:
+  nameResolution:
+    component: "structuredformat"
+    configuration:
+      structuredType: "json"  # or "yaml", "jsonFile", "yamlFile"
+      stringValue: '{"appInstances":{"myapp":[{"ipv4":"127.0.0.1","port":4433}]}}'
+```
+
+## Spec configuration fields
+
+| Field            | Required? | Description                                                                 | Example |
+|------------------|-----------|-----------------------------------------------------------------------------|---------|
+| `structuredType` | Yes       | Format and source type. Must be one of: `json`, `yaml`, `jsonFile`, `yamlFile` | `json` |
+| `stringValue`    | Conditional | Required when `structuredType` is `json` or `yaml`                         | `{"appInstances":{"myapp":[{"ipv4":"127.0.0.1","port":4433}]}}` |
+| `filePath`       | Conditional | Required when `structuredType` is `jsonFile` or `yamlFile`                 | `/etc/dapr/services.yaml` |
+
+> **Important**: Only one of `stringValue` or `filePath` should be provided, based on `structuredType`.
+
+## `appInstances` Schema
+
+The configuration must contain a top-level `appInstances` object that maps **service IDs** to **lists of address instances**.
+
+### Supported Address Fields
+
+| Field    | Type   | Required? | Description |
+|----------|--------|-----------|-------------|
+| `domain` | string | No        | Hostname or FQDN (e.g., `"api.example.com"`). Highest priority. |
+| `ipv4`   | string | No        | IPv4 address in dotted-decimal format (e.g., `"192.168.1.10"`). |
+| `ipv6`   | string | No        | Unbracketed IPv6 address (e.g., `"::1"`, `"2001:db8::1"`). |
+| `port`   | int    | **Yes**   | TCP port number (**must be 1–65535**). |
+
+> **Notes**:
+> - Service IDs must be non-empty strings.
+> - **At least one** of `domain`, `ipv4`, or `ipv6` must be non-empty per instance.
+> - Invalid or missing ports will cause initialization to fail.
+
+## Address Selection Logic
+
+For each instance, the resolver selects the **first non-empty address** in this priority order:
+
+1. `domain` → e.g., `github.com`  
+2. `ipv4` → e.g., `192.168.1.10`  
+3. `ipv6` → e.g., `::1`
+
+The final target address is formatted as:
+
+- `host:port` for domain/IPv4  
+- `[ipv6]:port` for IPv6 (automatically bracketed)
+
+If a service has **multiple instances**, one is selected **uniformly at random** on each call.
+
+## Examples
+
+### Inline JSON
+```yaml
+configuration:
+  structuredType: "json"
+  stringValue: '{"appInstances":{"myapp":[{"ipv4":"127.0.0.1","port":4433}]}}'
+```
+→ Resolves `"myapp"` to `127.0.0.1:4433`
+
+### Inline YAML (multi-line)
+```yaml
+configuration:
+  structuredType: "yaml"
+  stringValue: |
+    appInstances:
+      myapp:
+        - domain: "example.com"
+          port: 80
+        - ipv6: "::1"
+          port: 8080
+```
+→ Possible results: `example.com:80` or `[::1]:8080` (chosen randomly)
+
+### From External File
+```yaml
+configuration:
+  structuredType: "yamlFile"
+  filePath: "/etc/dapr/services.yaml"
+```
+
+With `/etc/dapr/services.yaml`:
+```yaml
+appInstances:
+  backend:
+    - ipv4: "10.0.0.5"
+      port: 3000
+```
+→ Resolves `"backend"` to `10.0.0.5:3000`