Add comprehensive link handling and serializer documentation

Co-authored-by: bastianeicher <414366+bastianeicher@users.noreply.github.com>

Author: Copilot

docs/endpoints/index.md

@@ -31,3 +31,19 @@ TypedRest provides a number of endpoint types modelling common REST patterns. Mo
 - [Streaming Collection endpoint](reactive/streaming-collection.md) - collection of entities observable as append-only stream
 
 The constructors of all endpoints except entry endpoints take a `referrer` parameter. This is uses to inherit relative URI bases and configuration such as [error handling](../error-handling/index.md) and [link handling](../link-handling/index.md).
+
+## Navigating Between Endpoints
+
+When creating child endpoints from a parent endpoint, the `referrer` parameter ensures that configuration is inherited, including serializers, error handlers, and authentication settings. This makes it easy to build endpoint hierarchies with consistent behavior.
+
+TypedRest supports multiple ways to link endpoints together:
+
+- **[Relative URIs](../link-handling/relative-uris.md)**: Hard-code the path to child resources using relative URIs. This is the simplest approach and works well for APIs with stable, predictable structures.
+
+- **[URI Templates](../link-handling/uri-templates.md)**: Use parameterized URI patterns that can be resolved with specific values. This is useful for dynamic navigation where paths depend on runtime data.
+
+- **[Link Headers](../link-handling/link-header.md)**: Extract links from HTTP Link headers provided by the server. This allows the server to guide navigation without embedding links in response bodies.
+
+- **[HAL Links](../link-handling/hal.md)**: Use links embedded in HAL-formatted JSON responses. This is a standard hypermedia format that combines data and navigation in a single response.
+
+For more details on link handling, see the [link handling documentation](../link-handling/index.md).

docs/link-handling/.pages

@@ -0,0 +1,7 @@
+nav:
+  - index.md
+  - relative-uris.md
+  - uri-templates.md
+  - link-header.md
+  - hal.md
+  - serializers.md

docs/link-handling/hal.md

@@ -0,0 +1,173 @@
+# HAL (Hypertext Application Language)
+
+TypedRest supports links encoded in resources using the HAL format. HAL provides a standard way to embed links and related resources directly in JSON responses.
+
+For details on the HAL specification, see the [HAL draft specification](https://datatracker.ietf.org/doc/html/draft-kelly-json-hal). TypedRest focuses on making HAL links easy to consume within your endpoint hierarchy.
+
+## HAL Content Type
+
+HAL uses the content type `application/hal+json` to indicate HAL-formatted responses. TypedRest automatically detects this content type and extracts links accordingly.
+
+A typical HAL response looks like:
+
+```json
+{
+  "_links": {
+    "self": {
+      "href": "/contacts/1337"
+    },
+    "edit": {
+      "href": "/contacts/1337/edit"
+    },
+    "next": {
+      "href": "/contacts/1338"
+    }
+  },
+  "name": "John Smith",
+  "email": "john@example.com"
+}
+```
+
+## Using HAL Links
+
+HAL links are accessed using the same `Link()` and `GetLinks()` methods as HTTP Link headers:
+
+=== "C#"
+
+    ```csharp
+    var contact = new ElementEndpoint<Contact>(client, relativeUri: "./contacts/1337");
+    var contactData = await contact.ReadAsync();
+    
+    // Retrieve a link from the HAL response
+    var editUri = contact.Link("edit");
+    if (editUri != null)
+    {
+        var editEndpoint = new Endpoint(contact, editUri);
+    }
+    ```
+
+=== "TypeScript"
+
+    ```typescript
+    const contact = new ElementEndpoint<Contact>(client, "./contacts/1337");
+    const contactData = await contact.read();
+    
+    // Retrieve a link from the HAL response
+    const editUri = contact.link("edit");
+    if (editUri) {
+        const editEndpoint = new Endpoint(contact, editUri);
+    }
+    ```
+
+## Multiple Links
+
+HAL supports multiple links with the same relation type. Use `GetLinks()` to retrieve all of them:
+
+=== "C#"
+
+    ```csharp
+    var resource = new ElementEndpoint<Resource>(client, relativeUri: "./resource");
+    await resource.ReadAsync();
+    
+    // Get all "alternate" links
+    var alternates = resource.GetLinks("alternate");
+    foreach (var alternate in alternates)
+    {
+        Console.WriteLine($"Alternate: {alternate}");
+    }
+    ```
+
+=== "TypeScript"
+
+    ```typescript
+    const resource = new ElementEndpoint<Resource>(client, "./resource");
+    await resource.read();
+    
+    // Get all "alternate" links
+    const alternates = resource.getLinks("alternate");
+    for (const alternate of alternates) {
+        console.log(`Alternate: ${alternate}`);
+    }
+    ```
+
+In HAL, multiple links are represented as an array:
+
+```json
+{
+  "_links": {
+    "alternate": [
+      {"href": "/resource.xml"},
+      {"href": "/resource.pdf"}
+    ]
+  }
+}
+```
+
+## Templated Links
+
+HAL supports templated links using URI Templates ([RFC 6570](https://tools.ietf.org/html/rfc6570)):
+
+```json
+{
+  "_links": {
+    "search": {
+      "href": "/contacts{?name,email}",
+      "templated": true
+    }
+  }
+}
+```
+
+Use `LinkTemplate()` to resolve templated links:
+
+=== "C#"
+
+    ```csharp
+    var contacts = new CollectionEndpoint<Contact>(client, relativeUri: "./contacts");
+    await contacts.ReadAllAsync();
+    
+    // Resolve the templated link
+    var searchUri = contacts.LinkTemplate("search", new {name = "Smith"});
+    ```
+
+=== "TypeScript"
+
+    ```typescript
+    const contacts = new CollectionEndpoint<Contact>(client, "./contacts");
+    await contacts.readAll();
+    
+    // Resolve the templated link
+    const searchUri = contacts.linkTemplate("search", {name: "Smith"});
+    ```
+
+## Combining with Link Headers
+
+TypedRest can extract links from both HTTP Link headers and HAL `_links` objects simultaneously. By default, both sources are checked, with header links taking precedence over HAL links when both provide a link with the same relation type.
+
+If you need more control over link extraction priority or want to use only specific sources, you can configure the link extraction behavior:
+
+=== "C#"
+
+    ```csharp
+    var endpoint = new Endpoint(new Uri("http://example.com/resource"));
+    
+    // Use AggregateLinkExtractor to combine multiple extractors
+    endpoint.LinkExtractor = new AggregateLinkExtractor(
+        new HeaderLinkExtractor(),
+        new HalLinkExtractor()
+    );
+    ```
+
+=== "TypeScript"
+
+    ```typescript
+    const endpoint = new Endpoint(new URL("http://example.com/resource"));
+    
+    // Use AggregateLinkExtractor to combine multiple extractors
+    endpoint.linkExtractor = new AggregateLinkExtractor(
+        new HeaderLinkExtractor(),
+        new HalLinkExtractor()
+    );
+    ```
+
+The `AggregateLinkExtractor` queries each extractor in order and returns the first match found, allowing you to control precedence by ordering the extractors.

docs/link-handling/index.md

@@ -1,8 +1,37 @@
 # Link handling
 
-TypedRest supports a variety of different links:
+TypedRest provides multiple ways to navigate between endpoints, ranging from simple hard-coded URIs to dynamic links provided by the server. This flexibility allows you to build clients that work with varying levels of API hypermedia support.
 
-- Hard-coded relative URIs between [endpoints](../endpoints/index.md)
-- Links transmitted via the HTTP Link Header
-- Links encoded in resources via HAL
-- URI templates
+## Link Resolution Methods
+
+TypedRest endpoints provide several methods for resolving links:
+
+- **`Link(rel)`**: Retrieves a link with the specified relation type from HTTP Link headers or HAL `_links`
+- **`GetLinks(rel)`**: Retrieves all links with the specified relation type (useful when multiple links share the same relation)
+- **`LinkTemplate(rel, variables)`**: Resolves a URI template with the specified relation type and variables
+
+These methods work consistently across all link sources, allowing your code to remain the same regardless of whether links come from headers, HAL, or default configurations.
+
+## Link Sources
+
+TypedRest supports multiple sources for link information:
+
+### [Relative URIs](relative-uris.md)
+
+Hard-coded relative URIs between [endpoints](../endpoints/index.md) are the simplest way to navigate. You specify the path when creating child endpoints, and TypedRest handles URI resolution. The non-standard `./` prefix pattern ensures proper path appending.
+
+### [URI Templates](uri-templates.md)
+
+URI Templates ([RFC 6570](https://tools.ietf.org/html/rfc6570)) allow parameterized URIs. Servers can provide templates that clients resolve with specific values, enabling flexible navigation without hard-coding every possible path.
+
+### [Link Headers](link-header.md)
+
+Links transmitted via the HTTP Link Header ([RFC 8288](https://tools.ietf.org/html/rfc8288)) provide navigation information without requiring specific response body formats. TypedRest also supports a non-standard `templated=true` extension for URI templates in headers.
+
+### [HAL](hal.md)
+
+Links encoded in resources via HAL (Hypertext Application Language) embed navigation directly in JSON responses using the `application/hal+json` content type and `_links` objects.
+
+## Serializers
+
+The [serializers](serializers.md) page documents how TypedRest handles different content formats (JSON, XML, BSON) and how serializer configuration is inherited between endpoints.

docs/link-handling/link-header.md

@@ -0,0 +1,126 @@
+# Link Header
+
+TypedRest can extract links from HTTP Link headers as specified in [RFC 8288](https://tools.ietf.org/html/rfc8288). This allows servers to provide navigation information without embedding it in response bodies.
+
+For details on the Link header format and semantics, see [RFC 8288](https://tools.ietf.org/html/rfc8288).
+
+## Link Header Format
+
+Link headers follow this basic format:
+
+```http
+Link: <https://example.com/page/2>; rel="next",
+      <https://example.com/page/1>; rel="prev"
+```
+
+Each link consists of:
+
+- A URI reference in angle brackets (`<URI>`)
+- One or more parameters, most importantly `rel` for the link relation type
+- Optional additional parameters like `title`
+
+## Extracting Links
+
+TypedRest automatically extracts links from HTTP responses. Use the `Link()` method to retrieve a specific link by its relation type:
+
+=== "C#"
+
+    ```csharp
+    var contacts = new CollectionEndpoint<Contact>(client, relativeUri: "./contacts");
+    await contacts.ReadAllAsync(); // This performs a GET request
+    
+    // Retrieve a link from the response headers
+    var nextPageUri = contacts.Link("next");
+    if (nextPageUri != null)
+    {
+        // Navigate to the next page
+        var nextPage = new CollectionEndpoint<Contact>(contacts, nextPageUri);
+    }
+    ```
+
+=== "TypeScript"
+
+    ```typescript
+    const contacts = new CollectionEndpoint<Contact>(client, "./contacts");
+    await contacts.readAll(); // This performs a GET request
+    
+    // Retrieve a link from the response headers
+    const nextPageUri = contacts.link("next");
+    if (nextPageUri) {
+        // Navigate to the next page
+        const nextPage = new CollectionEndpoint<Contact>(contacts, nextPageUri);
+    }
+    ```
+
+## Getting All Links
+
+Use `GetLinks()` to retrieve all links with a specific relation type (useful when multiple links share the same relation):
+
+=== "C#"
+
+    ```csharp
+    var endpoint = new Endpoint(new Uri("http://example.com/resource"));
+    await endpoint.ReadMetaAsync(); // HEAD request to fetch headers
+    
+    // Get all links with the "alternate" relation
+    var alternateLinks = endpoint.GetLinks("alternate");
+    foreach (var link in alternateLinks)
+    {
+        Console.WriteLine($"Alternate format: {link}");
+    }
+    ```
+
+=== "TypeScript"
+
+    ```typescript
+    const endpoint = new Endpoint(new URL("http://example.com/resource"));
+    await endpoint.readMeta(); // HEAD request to fetch headers
+    
+    // Get all links with the "alternate" relation
+    const alternateLinks = endpoint.getLinks("alternate");
+    for (const link of alternateLinks) {
+        console.log(`Alternate format: ${link}`);
+    }
+    ```
+
+## Templated Links in Headers
+
+TypedRest implements a non-standard extension: `templated=true` parameter for URI templates in Link headers.
+
+```http
+Link: </contacts{?name,email}>; rel="search"; templated=true
+```
+
+This combines the Link header mechanism with URI template support. While not part of RFC 8288, this extension provides a convenient way to express templated links without requiring HAL or another hypermedia format.
+
+When `templated=true` is present, use `LinkTemplate()` instead of `Link()`:
+
+=== "C#"
+
+    ```csharp
+    var contacts = new CollectionEndpoint<Contact>(client, relativeUri: "./contacts");
+    await contacts.ReadAllAsync();
+    
+    // Resolve the templated link
+    var searchUri = contacts.LinkTemplate("search", new {name = "Smith"});
+    ```
+
+=== "TypeScript"
+
+    ```typescript
+    const contacts = new CollectionEndpoint<Contact>(client, "./contacts");
+    await contacts.readAll();
+    
+    // Resolve the templated link
+    const searchUri = contacts.linkTemplate("search", {name: "Smith"});
+    ```
+
+## Supported Link Header Attributes
+
+TypedRest recognizes the following Link header parameters:
+
+- **`rel`**: The link relation type (required)
+- **`title`**: A human-readable title for the link (optional, currently extracted but not exposed)
+- **`templated`**: Non-standard extension indicating the URI is a template (optional)
+
+Other parameters defined in RFC 8288 may be present in headers but are not currently processed by TypedRest.