HONEYCOMB-10: JVpp documentation

Change-Id: Ibca8fc8c1962ca36d91898c1523afb2df6dfdc49
Signed-off-by: Maros Marsalek <mmarsale@cisco.com>

2 files changed, 214 insertions, 0 deletions

diff --git a/vpp-api/java/jvpp/Readme.txt b/vpp-api/java/jvpp/Readme.txt
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+= JVpp
+
+JVpp is JNI based Java API for VPP.
+
+== Features
+It is:
+
+* Asynchronous
+* Fully generated
+* Lightweight
+
+== Architecture
+JVpp and JNI
+
+
+ JVpp Java
+
+  /----------\             /--------\          /------------\    /------\
+  | VppConn* |             |  JVpp  |          |  Callbacks |    | DTOs |
+  \----+-----/             \----+---/          \------+-----/    \------/
+       ^                        ^                     ^
+       | implements             | implements          | implements
+  /----+---------\         /----+-------\      /------+-----------\
+  | VppConnImpl* +<--------+  JVppImpl  |      |  GlobalCallback  |
+  \--------------/   uses  \---+--------/      \-------+----------/
+                               |                       ^
+                               | uses                  | calls back
+                               |                       |
+-------------------------------|-----------------------|---------------------
+                               |                       |
+                               |       +---------------+
+ C JNI                         |       |
+                               v       |              /------------\
+                           /---+-------+--\     +---->+   jvpp.h*  |
+                           |              +-----+     \------------/
+                           |    jvpp.c*   |
+                           |              +-----+     /------------\
+                           \--------------/     +---->+ jvpp_gen.h |
+                                                      \------------/
+
+* Components marked with an asterisk contain manually crafted Java code, which in addition
+to generated classes form jvpp. Exception applies to Callbacks and DTOs, since there are
+manually crafted marker interfaces in callback and dto package (dto/JVppRequest, dto/JVppReply,
+dto/JVppDump, dto/JVppReplyDump, callback/JVppCallback)
+
+Note: jvpp.c calls back the GlobalCallback instance with every response. An instance of the
+GlobalCallback is provided to jvpp.c by VppConnImpl while connecting to VPP.
+
+Part of the JVpp is also Future facade. It is asynchronous API returning Future objects
+on top of low level JVpp.
+
+
+Future facade
+
+        /-------------\           /--------------------\
+        | FutureJVpp* |       +-->+ FutureJVppRegistry |
+        \-----+-------/       |   \----------+---------/
+              ^               |              ^
+              | implements    | uses         | uses
+              |               |              |
+     /--------+----------\    |   /----------+---------\
+     | FutureJVppFacade* +----+   | FutureJVppCallback |
+     \---------+---------/        \----------+---------/
+               |                             |
+---------------|-----------------------------|-------------------------------
+               | uses                        | implements
+JVpp Java      |                             |
+               |                             |
+ /---------\   |                             |
+ |   JVpp  +<--+                             |
+ \----+----/                                 |
+      ^                                      |
+      | implements                           v
+ /----+-------\                   /----------+-------\
+ |  JVppImpl  |                   |  GlobalCallback  |
+ \------------/                   \------------------/
+
+
+
+Another useful utility of the JVpp is Callback facade. It is asynchronous API
+capable of calling specific callback instance (provided when performing a call)
+per call.
+
+
+Callback facade
+
+        /--------------\            /----------------------\
+        | CallbackJVpp |        +-->+ CallbackJVppRegistry |
+        \-----+--------/        |   \----------+-----------/
+              ^                 |              ^
+              | implements      | uses         | uses
+              |                 |              |
+     /--------+-----------\     |   /----------+-----------\
+     | CallbackJVppFacade +-----+   | CallbackJVppCallback |
+     \---------+----------/         \----------+-----------/
+               |                             |
+---------------|-----------------------------|-------------------------------
+               | uses                        | implements
+JVpp Java      |                             |
+               |                             |
+ /---------\   |                             |
+ |   JVpp  +<--+                             |
+ \----+----/                                 |
+      ^                                      |
+      | implements                           v
+ /----+-------\                   /----------+-------\
+ |  JVppImpl  |                   |  GlobalCallback  |
+ \------------/                   \------------------/
+
+
+
+== Package structure
+
+* *org.openvpp.jvpp* - top level package for generated JVpp interface+ implementation and hand-crafted
+VppConnection interface + implementation
+
+** *dto* - package for DTOs generated from VPP API structures + base/marker hand-crafted interfaces
+** *callback* - package for low-level JVpp callbacks and a global callback interface implementing each of the low-level JVppcallbacks
+** *future* - package for future based facade on top of JVpp and callbacks
+** *callfacade* - package for callback based facade on top of JVpp and callbacks. Allowing
+users to provide callback per request
+** *test* - package for JVpp standalone tests. Can also serve as samples for JVpp.
+
+C code is structured into 3 files:
+
+* *jvpp.c* - includes jvpp.h and jvpp_gen.h + contains hand crafted code for:
+
+** VPP connection open/close
+** Rx thread to java thread attach
+** Callback instance store
+* *jvpp.h* - contains hand-crafted macros and structures used by jvpp.c
+* *jvpp_gen.h* - contains JNI compatible handlers for each VPP request and reply
+
+== Code generators
+All of the required code except the base/marker interfaces is generated using
+simple python2 code generators. The generators use __defs_vpp_papi.py__ input
+file produced by __vppapigen__ from vpe.api file.
+
+=== JNI compatible C code
+Produces __jvpp_gen.h__ file containing JNI compatible handlers for each VPP
+request and reply.
+
+[NOTE]
+====
+Source: jvpp_c_gen.py
+====
+
+=== Request/Reply DTOs
+For all the structures in __defs_vpp_papi.py__ a POJO DTO is produced. Logically,
+there are 4 types of DTOs:
+
+* Request - requests that can be sent to VPP and only a single response is expected
+* DumpRequest - requests that can be sent to VPP and a stream of responses is expected
+* Reply - reply to a simple request or a single response from dump triggered response stream
+* ReplyDump - collection of replies from a single dump request
+* Notifications/Events - Not implemented yet
+
+[NOTE]
+====
+Source: dto_gen.py
+====
+
+=== JVpp
+Produces __JVpp.java__ and __JVppImpl.java__. This is the layer right above JNI compatible C
+code.
+
+[NOTE]
+====
+Source: jvpp_impl_gen.py
+====
+
+=== Callbacks
+Produces callback interface for each VPP reply + a global callback interface called
+__JVppGlobalCallback.java__ aggregating all of the callback interfaces. The JNI
+compatible C code expects only a single instance of this global callback and calls
+it with every reply.
+
+[NOTE]
+====
+Source: callback_gen.py
+====
+
+=== Future facade
+Produces an asynchronous facade on top of JVpp and callbacks, which returns a Future that provides
+matching reply once VPP invocation finishes. Sources produced:
+__FutureJVpp.java, FutureJVppFacade.java and FutureJVppCallback.java__
+
+[NOTE]
+====
+Source: jvpp_future_facade_gen.py
+====
+
+=== Callback facade
+Similar to future facade, only this facade takes callback objects as part of the invocation
+and the callback is called with result once VPP invocation finishes. Sources produced:
+__CallbackJVpp.java, CallbackJVppFacade.java and CallbackJVppCallback.java__
+
+[NOTE]
+====
+Source: jvpp_callback_facade_gen.py
+====
diff --git a/vpp-api/java/jvpp/org/openvpp/jvpp/test/Readme.txt b/vpp-api/java/jvpp/org/openvpp/jvpp/test/Readme.txt
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+This package contains basic tests for jvpp. To run the tests:
+
+- Make sure VPP is running
+- From VPP's build-root/ folder execute:
+  - sudo java -cp .:build-vpp-native/vpp-api/java/jvpp-1.0.0.jar org.openvpp.jvpp.test.ControlPingTest
+  - sudo java -cp .:build-vpp-native/vpp-api/java/jvpp-1.0.0.jar org.openvpp.jvpp.test.FutureApiTest
+  - sudo java -cp .:build-vpp-native/vpp-api/java/jvpp-1.0.0.jar org.openvpp.jvpp.test.CallbackApiTest
+
+Available tests:
+ControlPingTest - Simple test executing a single control ping using low level JVpp APIs
+CallbackApiTest - Similar to ControlPingTest, invokes more complex calls (e.g. interface dump) using low level JVpp APIs
+FutureApiTest - Execution of more complex calls using Future based JVpp facade
+CallbackJVppFacadeTest - Execution of more complex calls using Callback based JVpp facade
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