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* #296 renamed configuration.json to ocelot.json in preparation * removed things we dont need for tests * another file we dont need * removed some async we dont need * refactoring to consolidate configuration code * removed another pointless abstraction * #296 started writing merge code * #296 coming up with ideas for this config merging * #296 still hacking this idea around * #296 will now do a crappy merge on the configuration * #296 change so tests pass on windows
80 lines
3.2 KiB
ReStructuredText
80 lines
3.2 KiB
ReStructuredText
Delegating Handers
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==================
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Ocelot allows the user to add delegating handlers to the HttpClient transport. This feature was requested `GitHub #208 <https://github.com/TomPallister/Ocelot/issues/208>`_
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and I decided that it was going to be useful in various ways. Since then we extended it in `GitHub #264 <https://github.com/TomPallister/Ocelot/issues/264>`_.
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Usage
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^^^^^
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In order to add delegating handlers to the HttpClient transport you need to do two main things.
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First in order to create a class that can be used a delegating handler it must look as follows. We are going to register these handlers in the
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asp.net core container so you can inject any other services you have registered into the constructor of your handler.
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.. code-block:: csharp
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public class FakeHandler : DelegatingHandler
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{
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protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
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{
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//do stuff and optionally call the base handler..
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return await base.SendAsync(request, cancellationToken);
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}
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}
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Next you must add the handlers to Ocelot's container either as singleton like follows..
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.. code-block:: csharp
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services.AddOcelot()
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.AddSingletonDelegatingHandler<FakeHandler>()
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.AddSingletonDelegatingHandler<FakeHandlerTwo>()
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Or transient as below...
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.. code-block:: csharp
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services.AddOcelot()
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.AddTransientDelegatingHandler<FakeHandler>()
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.AddTransientDelegatingHandler<FakeHandlerTwo>()
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Both of these Add methods have a default parameter called global which is set to false. If it is false then the intent of
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the DelegatingHandler is to be applied to specific ReRoutes via ocelot.json (more on that later). If it is set to true
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then it becomes a global handler and will be applied to all ReRoutes.
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e.g.
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.. code-block:: csharp
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services.AddOcelot()
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.AddSingletonDelegatingHandler<FakeHandler>(true)
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Or transient as below...
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.. code-block:: csharp
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services.AddOcelot()
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.AddTransientDelegatingHandler<FakeHandler>(true)
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Finally if you want ReRoute specific DelegatingHandlers or to order your specific and / or global (more on this later) DelegatingHandlers
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then you must add the following json to the specific ReRoute in ocelot.json. The names in the array must match the class names of your
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DelegatingHandlers for Ocelot to match them together.
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.. code-block:: json
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"DelegatingHandlers": [
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"FakeHandlerTwo",
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"FakeHandler"
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]
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You can have as many DelegatingHandlers as you want and they are run in the following order:
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1. Any globals that are left in the order they were added to services and are not in the DelegatingHandlers array from ocelot.json.
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2. Any non global DelegatingHandlers plus any globals that were in the DelegatingHandlers array from ocelot.json ordered as they are in the DelegatingHandlers array.
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3. Tracing DelegatingHandler if enabled (see tracing docs).
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4. QoS DelegatingHandler if enabled (see QoS docs).
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5. The HttpClient sends the HttpRequestMessage.
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Hopefully other people will find this feature useful!
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