70 lines
3.2 KiB
ReStructuredText
70 lines
3.2 KiB
ReStructuredText
.. _http-javadsl-migration-guide:
|
||
|
||
Migration Guide from "old" HTTP JavaDSL
|
||
=======================================
|
||
|
||
The so-called "old" JavaDSL for Akka HTTP was initially developed during the project's experimental phase,
|
||
and thanks to multiple user comments and contributions we were able to come up with a more Java 8 "feel",
|
||
which at the same time is also closer to the existing ScalaDSL.
|
||
|
||
The previous DSL has been entirely removed and replaced with the the so-called "new" one.
|
||
Upgrading to the new DSL is **highly encouraged** since the old one not only was rather hard to work with,
|
||
it actually was not possible to express many typical use-cases using it.
|
||
|
||
The most major changes include:
|
||
|
||
|
||
HttpApp is gone
|
||
---------------
|
||
``HttpApp`` (a helper class containing a ``main()`` implementation) is gone, as we would like to encourage understanding
|
||
how the various elements of the API fit together.
|
||
|
||
Instead developers should start applications "manually", by converting a ``Route`` to a ``Flow<HttpRequest, HttpResponse, ?>``
|
||
using the ``Route.flow`` method. For examples of full apps refer to :ref:`http-testkit-java`.
|
||
|
||
``RequestVal`` is gone
|
||
----------------------
|
||
The old API heavily relied on the concept of "request values" which could be used to extract a value from a request context.
|
||
|
||
Based on community feedback and our own experience we found them too hard to work with in more complex settings.
|
||
The concept of a request value has been completely removed, and replaced with proper "directives", exacly like in the ScalaDSL.
|
||
|
||
**Previously**::
|
||
|
||
RequestVal<Host> host = Headers.byClass(Host.class).instance();
|
||
|
||
final Route route =
|
||
route(
|
||
handleWith1(host, (ctx, h) ->
|
||
ctx.complete(String.format("Host header was: %s", h.host()))
|
||
)
|
||
);
|
||
|
||
|
||
**Now**::
|
||
|
||
final Route route =
|
||
headerValueByType(Host.class, host -> complete("Host was: " + host));
|
||
|
||
All of ScalaDSL routing has corresponding JavaDSL
|
||
-------------------------------------------------
|
||
Both ``Route``, ``RouteResult`` and other important core concepts such as ``Rejections`` are now modeled 1:1 with Scala,
|
||
making is much simpler to understand one API based on the other one – tremendously useful when learning about some nice
|
||
pattern from blogs which used Scala, yet need to apply it in Java and the other way around.
|
||
|
||
It is now possible to implement marshallers using Java. Refer to :ref:`marshalling-java` for details.
|
||
|
||
Some complete* overloads changed to completeOK*
|
||
-----------------------------------------------
|
||
In JavaDSL when complete is called with only an entity, the ``OK`` response code is *assumed*,
|
||
to make this more explicit these methods contain the word ``OK`` in them.
|
||
|
||
This has been made more consistent than previously, across all overloads and Future-versions of these APIs.
|
||
|
||
Migration help
|
||
--------------
|
||
As always, feel free to reach out via the `akka-user <https://groups.google.com/forum/#!searchin/akka-user/>`_ mailing list or gitter channels,
|
||
to seek help or guidance when migrating from the old APIs.
|
||
|
||
For Lightbend subscription owners it is possible to reach out to the core team for help in the migration by asking specific
|
||
questions via the `Lightbend customer portal <https://portal.lightbend.com/>`_.
|