提交: a9e469879f744abd94629bafa82ac94557f8bb55 - MESS (hg)

Commit MetaInfo

• 修订版: a9e469879f744abd94629bafa82ac94557f8bb55 (tree)
• 时间: 2020-03-26 20:17:31
• 作者: Albert Mietus < albert AT mietus DOT nl >
• Commiter: Albert Mietus < albert AT mietus DOT nl >

Log Message

PubSub: finisched practice (final draft)

更改概述

• modified: SoftwareCompetence/DesignWorkShops/PubSub/practice/index.rst

差异

diff -r 79d39aa88931 -r a9e469879f74 SoftwareCompetence/DesignWorkShops/PubSub/practice/index.rst
--- a/SoftwareCompetence/DesignWorkShops/PubSub/practice/index.rst	Thu Mar 26 11:05:57 2020 +0100
+++ b/SoftwareCompetence/DesignWorkShops/PubSub/practice/index.rst	Thu Mar 26 12:17:31 2020 +0100
@@ -4,11 +4,14 @@
 Practice
 ========
 
+This last section of this :ref:`PubSub` workshop is short. It only contain some practice (ideas). Two are on practicing
+your design skills, the other two are more coding-oriented.
 
-Design Analye
+
+Design Analyse
 ==============
 
-Given the python implementation, including the shown “Use-Cases”: Analyse the design in detail
+Given the python implementation, including the shown “Use-Cases”: Analyse the design in detail:
 
 1. Make a (quick) static design-analyse.
 
@@ -19,18 +22,66 @@
    At least a sequence-diagram for each of the “use-cases”
 
 Port to C/C++
-=============
+--------------
 
 3. Can you port (or re-implement) the python examples to C/C++?
 
-   Surely, you have to change some details; as a generic data-type (“value”) is not available.
-
-   It is fine, to use a *string-type*. And just “print” it in the demo-callbacks (like we do)
+   Surely, you have to change some details; as a generic data-type (“value”) is not available. It is fine, to use a
+   *string-type*. And just “print” it in the demo-callbacks (like I did).
 
 Design a cached, distributed one
 ================================
 
+The shown (conceptional) implementation works for a single process; optional with threads. In this exercise, you are
+going to extent that for “network use”; although it will be a simple, conceptional one. Many existing protocols and
+frameworks do exist already! The goal is *not* to challenge them, nor to *use* them.
 
-.. todo:: Complete this section
+The goal is to practice your design skills!
+|BR|
+So, this is a (fun) design-exercise. You should be able to make a (full, conceptional) design in about an hour. That does
+imply many fancy options should be left-out:-)
 
-   * Design a cached, distributed one
+4. Extent the current interface to allow pub/sub between multiple processes; optionally running on multiple computers
+   (on the same network).
+
+   * The current API (:class:`~pubsub.Topic`, :meth:`~pubsub.Topic.publish` & :meth:`~pubsub.Topic.subscribe`) are not
+     allowed to change. Adding parameters to the class initiation (“the constructor” in C++) is allowed. Adding extra
+     methods is also allowed (but see below!).
+
+   * All existing Use-Cases **should** keep working (both the shown one, as many others).
+
+     * The main methods (:meth:`~pubsub.Topic.publish` & :meth:`~pubsub.Topic.subscribe`) should remain exactly the
+       same. No more parameters!
+
+     * The default behavior should be “local” (not distributed).
+
+   * There is no requirement for performance. But it is expected that a second “network-get” will be resolved
+     locally. So, use a cache to minimize networking
+
+   * The networking should use standard TCP/IP networking (“sockets”). No other network libraries/frameworks are
+     allowed.
+
+     * A simple “serialise” will do. Assume, all computers/processes use the same endianness and other encodings.
+       |BR|
+       Again, use “strings” (only); then this part is easy.
+
+.. hint:: `Deamon <https://en.wikipedia.org/wiki/Daemon_(computing)>`_ &  `lib <https://en.wikipedia.org/wiki/Library_(computing)>`_
+
+   An easy way to design this is to foresee *one* processes handle all the administration (the core of
+   :class:`~pubsub.Topic`); including “calling” all the callbacks.
+   |BR|
+   This is typically called a **daemon**, or *services* on Windows.
+
+   To hide all the networking stuff, arrange a (small) library, that acts as `facade <https://en.wikipedia.org/wiki/Facade_pattern>`_
+   and provides the (extended) :ref:`PubSub_API`.
+
+
+Implement it
+------------
+
+5. To check your design above is great, now implement it.
+
+   Or better: implement the design of you co-trainee, and ask him to implement yours!
+
+Remember, a design is a communication-tool: A great design contains exactly those details that your coworker needs to
+implement is as it is meant to be, but no more. (S)He should have some freedom to optimize implementation-details.