Skip to content
Projects
Groups
Snippets
Help
Loading...
Help
Support
Keyboard shortcuts
?
Submit feedback
Contribute to GitLab
Sign in / Register
Toggle navigation
A
Actor Framework
Project overview
Project overview
Details
Activity
Releases
Repository
Repository
Files
Commits
Branches
Tags
Contributors
Graph
Compare
Issues
0
Issues
0
List
Boards
Labels
Milestones
Merge Requests
0
Merge Requests
0
CI / CD
CI / CD
Pipelines
Jobs
Schedules
Operations
Operations
Metrics
Environments
Analytics
Analytics
CI / CD
Repository
Value Stream
Wiki
Wiki
Snippets
Snippets
Members
Members
Collapse sidebar
Close sidebar
Activity
Graph
Create a new issue
Jobs
Commits
Issue Boards
Open sidebar
cpp-libs
Actor Framework
Commits
d9255378
Commit
d9255378
authored
Mar 21, 2023
by
Dominik Charousset
Browse files
Options
Browse Files
Download
Email Patches
Plain Diff
Document the protocol layering API
parent
09e62f81
Changes
2
Expand all
Hide whitespace changes
Inline
Side-by-side
Showing
2 changed files
with
73 additions
and
276 deletions
+73
-276
libcaf_net/ProtocolLayering.rst
libcaf_net/ProtocolLayering.rst
+0
-253
manual/net/Overview.rst
manual/net/Overview.rst
+73
-23
No files found.
libcaf_net/ProtocolLayering.rst
deleted
100644 → 0
View file @
09e62f81
This diff is collapsed.
Click to expand it.
manual/net/Overview.rst
View file @
d9255378
...
@@ -21,10 +21,6 @@ bottom up, usually starting at the actor system. For example:
...
@@ -21,10 +21,6 @@ bottom up, usually starting at the actor system. For example:
namespace ws = caf::net::web_socket;
namespace ws = caf::net::web_socket;
auto conn = ws::with(sys)
auto conn = ws::with(sys)
.connect("localhost", 8080)
.connect("localhost", 8080)
.do_on_error([](const caf::error& err) {
std::cerr << "*** failed to connect: " << to_string(err)
<< std::endl;
})
.start([&sys](auto pull, auto push) {
.start([&sys](auto pull, auto push) {
sys.spawn(my_actor, pull, push);
sys.spawn(my_actor, pull, push);
});
});
...
@@ -46,19 +42,13 @@ back to the sender could look like this:
...
@@ -46,19 +42,13 @@ back to the sender could look like this:
self->make_observable().from_resource(pull).subscribe(push);
self->make_observable().from_resource(pull).subscribe(push);
}
}
In general,
connecting
to a server follows the pattern:
In general,
starting a client that connects
to a server follows the pattern:
.. code-block:: C++
.. code-block:: C++
PROTOCOL::with(CONTEXT).connect(WHERE).start(ON_CONNECT);
PROTOCOL::with(CONTEXT).connect(WHERE).start(ON_CONNECT);
To establish the connection asynchronously:
Starting a server uses ``accept`` instead:
.. code-block:: C++
PROTOCOL::with(CONTEXT).async_connect(WHERE).start(ON_CONNECT);
And for accepting incoming connections:
.. code-block:: C++
.. code-block:: C++
...
@@ -72,17 +62,77 @@ the background such as a Prometheus endpoint. These services take no callback in
...
@@ -72,17 +62,77 @@ the background such as a Prometheus endpoint. These services take no callback in
prometheus::with(sys).accept(8008).start();
prometheus::with(sys).accept(8008).start();
In all cases, CAF returns a ``disposable`` that allows users to cancel the
In all cases, CAF returns ``expected<disposable>``. The ``disposble`` allows
activity at any time. Note: when canceling a server, it only disposes the accept
users to cancel the activity at any time. Note: when canceling a server, it only
socket itself. Previously established connections remain unaffected.
disposes the accept socket itself. Previously established connections remain
unaffected.
For error reporting, most factories allow setting a callback with
For error reporting, most factories also allow setting a callback with
``do_on_error``.
``do_on_error``. This can be useful for ignoring the result value but still
reporting errors.
Many protocols also accept additional configuration parameters. For example, the
Many protocols also accept additional configuration parameters. For example, the
factory for establishing WebSocket connections allows users to tweak parameters
``connect`` API also allows to configure multiple connection attempts.
for the handshake such as protocols or extensions fields. These options are
listed at the documentation for the individual protocols.
Protocol Layering
-----------------
Layering
--------
Layering plays an important role in the design of the ``caf.net`` module. When
implementing a new protocol for ``caf.net``, this protocol should integrate
naturally with any number of other protocols. To enable this key property,
``caf.net`` establishes a set of conventions and abstract interfaces.
Please note that the protocol layering is meant for adding new networking
capabilities to CAF, but we do not recommend using the protocol stacks directly
in application code. The protocol stacks are meant as building blocks for
higher-level the declarative, high-level APIs.
A *protocol layer* is a class that implements a single processing step in a
communication pipeline. Multiple layers are organized in a *protocol stack*.
Each layer may only communicate with its direct predecessor or successor in the
stack.
At the bottom of the protocol stack is usually a *transport layer*. For example,
an ``octet_stream::transport`` that manages a stream socket and provides access
to input and output buffers to the upper layer.
At the top of the protocol is an *application* that utilizes the lower layers
for communication via the network. Applications should only rely on the
*abstract interface type* when communicating with their lower layer. For
example, an application that processes a data stream should not implement
against a TCP socket interface directly. By programming against the abstract
interface types of ``caf.net``, users can instantiate an application with any
compatible protocol stack of their choosing. For example, a user may add extra
security by using application-level data encryption or combine a custom datagram
transport with protocol layers that establish ordering and reliability to
emulate a stream.
By default, ``caf.net`` distinguishes between these abstract interface types:
* *datagram*: A datagram interface provides access to some basic transfer units
that may arrive out of order or not at all.
* *stream*: An octet stream interface represents a sequence of Bytes,
transmitted reliable and in order.
* *message*: A message interface provides access to high-level, structured data.
Messages usually consist of a header and a payload. A single message may span
multiple datagrams.
Note that each interface type also depends on the *direction*, i.e., whether
talking to the upper or lower level. Incoming data always travels the protocol
stack *up*. Outgoing data always travels the protocol stack *down*.
A protocol stack always lives in a ``socket_manager``. The deepest layer in the
stack is always a ``socket_event_layer`` that simply turns events on sockets
(e.g., ready-to-read) into function calls. Only transport layers will implement
this layer.
A transport layer then responds to socket events by reading and writing to the
socket. The transport acts as the lower layer for the next layer in the
processing chain. For example, the ``octet_stream::transport`` is an
``octet_stream::lower_layer``. To interface with an octet stream, user-defined
classes implement ``octet_stream::upper_layer``.
When instantiating a protocol stack, each layer is represented by a concrete
object and we build the pipeline from top to bottom, i.e., we create the highest
layer first and then pass the last layer to the next lower layer until arriving
at the socket manager.
Write
Preview
Markdown
is supported
0%
Try again
or
attach a new file
Attach a file
Cancel
You are about to add
0
people
to the discussion. Proceed with caution.
Finish editing this message first!
Cancel
Please
register
or
sign in
to comment