X-Git-Url: https://gerrit.automotivelinux.org/gerrit/gitweb?a=blobdiff_plain;f=doc%2Fafb-application-writing.html;h=12a2f13feca66c95b3e9a859a6b82983fcccce6b;hb=540ece2baf7de59565b42d427e206769ec4da56a;hp=7c0278da7fb1eb0aa7a1c360df5c81c3476ca9eb;hpb=0156b1645a201e44d5285c96d32cbfa5a9eb6814;p=src%2Fapp-framework-binder.git diff --git a/doc/afb-application-writing.html b/doc/afb-application-writing.html index 7c0278da..12a2f13f 100644 --- a/doc/afb-application-writing.html +++ b/doc/afb-application-writing.html @@ -1,106 +1,232 @@ + - - + + + + + + HOWTO WRITE an APPLICATION above AGL FRAMEWORK + + + + - -

HOWTO WRITE an APPLICATION above AGL FRAMEWORK

- -
version: 1
-Date:    30 mai 2016
-Author:  José Bollo
-
- -

- - -

Writing an HTML5 application

- -

Developpers of HTML5 applications (client side) can easyly create -applications for AGL framework using their prefered -HTML framework.

- -

Developpers can also create powerful server side plugins to improve -their application. This server side plugin should return the mime-type -application/json and can be accessed either by HTTP or by Websockets.

- -

In a near future, the JSON-RPC protocol will be available together -with the current x-afb-json1 protocol.

- +
+

HOWTO WRITE an APPLICATION above AGL FRAMEWORK

+

José Bollo

+

Fulup Ar Foll

+

24 juin 2016

+
+ +

HOWTO WRITE an APPLICATION above AGL FRAMEWORK

+

Programmation Languages for Applications

+

Writing an HTML5 application

+

Developers of HTML5 applications (client side) can easily create applications for AGL framework using their preferred HTML5 framework.

+

Developers may also take advantage of powerful server side plugins to improve application behavior. Server side plugins return an application/json mine-type and can be accessed though either HTTP or Websockets.

+

In a near future, JSON-RPC protocol should be added to complete current x-afb-json1 protocol.

Two examples of HTML5 applications are given:

- - - - -

Writing a Qt application

- -

Writing Qt applications is also possible because Qt offers APIs to -make HTTP queries and to connect using WebSockets.

- -

It is even possible to write a QML application. -It is demontrated by the sample application token-websock:

- +

Writing a Qt application

+

Writing Qt applications is also supported. Qt offers standard API to send request through HTTP or WebSockets.

+

It is also possible to write QML applications. A sample QML application [token-websock] is avaliable..

- - - -

Writing a C application

- -

C applications can use the binder afb-daemon through a websocket connection.

- -

The library libafbwsc is made for C clients that want -to connect to the afb-daemon binder.

- -

The program afb-client-demo is the C program that use -the provided library libafbwsc. -Its source code is here -src/afb-client-demo.c.

- -

The current implementation use libsystemd and file descriptors. -This may be changed in the future to also support secure sockets -and being less dependant of libsystemd.

- - -

Handling sessions within applications

- - -

Exchanging tokens

- -

Applications are communicating with their binder afb-daemon using -a network connection or a kind of network connection (unix domain -socket isn’t currently implemented but could be used in near future). -Also, HTTP protocol is not a connected protocol. It means that -the socket connection can not be used to authenticate a client.

- -

For this reason, the binder should authenticate the application -by using a commonly shared secret named token.

- -

At start, the framework communicate a common secret to both the binder -and its client: the application. When the application

- - -

Handling sessions

+

Writing "C" application

+

C applications can use afb-daemon binder through a websocket connection.

+

The library libafbwsc is provided for C clients that need to connect with an afb-daemon binder.

+

The program afb-client-demo is the C example that use libafbwsc library. Source code is available here src/afb-client-demo.c.

+

Current implementation relies on libsystemd and file descriptors. This model might be review in the future to support secure sockets and free the dependency with libsystemd.

+

Handling sessions within applications

+

Applications should understand sessions and tokens management when interacting with afb-daemon binder.

+

Applications are communicating with their private binder(afb-daemon) using a network connection or potentially any other connection channel. While current version does not yet implement unix domain this feature might be added in a near future. Developers need to be warn that HTTP protocol is a none connected protocol. This prevents from using HTTP socket connection to authenticate clients.

+

For this reason, the binder should authenticate the application by using a shared secret. The secret is named "token" and the identification of client is named "session".

+

The examples token-websock.qml and afb-client are demonstrating how authentication and sessions are managed.

+

Handling sessions

+

Plugins and other binder feature need to keep track of client instances. This is especially important for plugins running as services as they may typically have to keep each client's data separated.

+

For HTML5 applications, the web runtime handles the cookie of session that the binder afb-daemon automatically sets.

+

Session identifier can be set using the parameter uuid or x-afb-uuid in URI requests. Within current version of the framework session UUID is supported by both HTTP requests and websocket negotiation.

+

Exchanging tokens

+

At application start, AGL framework communicates a shared secret to both binder and client application. This initial secret is called the "initial token".

+

For each of its client application, the binder manages a current active token for session management. This authentication token can be use to restrict access to some plugin's methods.

+

The token must be included in URI request on HTTP or during websockets connection using parameter token or x-afb-token.

+

To ensure security, tokens must be refreshed periodically.

+

Example of session management

+

In following examples, we suppose that afb-daemon is launched with something equivalent to:

+
$ afb-daemon --port=1234 --token=123456 [...]
+

making the expectation that AuthLogin plugin is requested as default.

+

Using curl

+

First, connects with the initial token, 123456:

+
$ curl http://localhost:1234/api/auth/connect?token=123456
+{
+  "jtype": "afb-reply",
+  "request": {
+     "status": "success",
+     "token": "0aef6841-2ddd-436d-b961-ae78da3b5c5f",
+     "uuid": "850c4594-1be1-4e9b-9fcc-38cc3e6ff015"
+  },
+  "response": {"token": "A New Token and Session Context Was Created"}
+}
+

It returns an answer containing session UUID, 850c4594-1be1-4e9b-9fcc-38cc3e6ff015, and a refreshed token, 850c4594-1be1-4e9b-9fcc-38cc3e6ff015.

+

Check if session and token is valid:

+
$ curl http://localhost:1234/api/auth/check?token=0aef6841-2ddd-436d-b961-ae78da3b5c5f\&uuid=850c4594-1be1-4e9b-9fcc-38cc3e6ff015
+{
+  "jtype": "afb-reply",
+  "request": {"status":"success"},
+  "response": {"isvalid":true}
+}
+

Refresh the token:

+
$ curl http://localhost:1234/api/auth/refresh?token=0aef6841-2ddd-436d-b961-ae78da3b5c5f\&uuid=850c4594-1be1-4e9b-9fcc-38cc3e6ff015
+{
+  "jtype": "afb-reply",
+  "request": {
+     "status":"success",
+     "token":"b8ec3ec3-6ffe-448c-9a6c-efda69ad7bd9"
+  },
+  "response": {"token":"Token was refreshed"}
+}
+

Close the session:

+
curl http://localhost:1234/api/auth/logout?token=b8ec3ec3-6ffe-448c-9a6c-efda69ad7bd9\&uuid=850c4594-1be1-4e9b-9fcc-38cc3e6ff015
+{
+  "jtype": "afb-reply",
+  "request": {"status": "success"},
+  "response": {"info":"Token and all resources are released"}
+}
+

Checking on closed session for uuid should be refused:

+
curl http://localhost:1234/api/auth/check?token=b8ec3ec3-6ffe-448c-9a6c-efda69ad7bd9\&uuid=850c4594-1be1-4e9b-9fcc-38cc3e6ff015
+{
+  "jtype": "afb-reply",
+  "request": {
+     "status": "failed",
+     "info": "invalid token's identity"
+  }
+}
+

Using afb-client-demo

+
+

The program is packaged within AGL in the rpm libafbwsc-dev

+
+

Here is an example of exchange using afb-client-demo:

+
$ afb-client-demo ws://localhost:1234/api?token=123456
+auth connect
+ON-REPLY 1:auth/connect: {"jtype":"afb-reply","request":{"status":"success",
+   "token":"63f71a29-8b52-4f9b-829f-b3028ba46b68","uuid":"5fcc3f3d-4b84-4fc7-ba66-2d8bd34ae7d1"},
+   "response":{"token":"A New Token and Session Context Was Created"}}
+auth check
+ON-REPLY 2:auth/check: {"jtype":"afb-reply","request":{"status":"success"},"response":{"isvalid":true}}
+auth refresh
+ON-REPLY 4:auth/refresh: {"jtype":"afb-reply","request":{"status":"success",
+   "token":"8b8ba8f4-1b0c-48fa-962d-4a00a8c9157e"},"response":{"token":"Token was refreshed"}}
+auth check
+ON-REPLY 5:auth/check: {"jtype":"afb-reply","request":{"status":"success"},"response":{"isvalid":true}}
+auth refresh
+ON-REPLY 6:auth/refresh: {"jtype":"afb-reply","request":{"status":"success",
+   "token":"e83b36f8-d945-463d-b983-5d8ed73ba529"},"response":{"token":"Token was refreshed"}}
+

After closing connection, reconnect as here after:

+
$ afb-client-demo ws://localhost:1234/api?token=e83b36f8-d945-463d-b983-5d8ed73ba529\&uuid=5fcc3f3d-4b84-4fc7-ba66-2d8bd34ae7d1 auth check
+ON-REPLY 1:auth/check: {"jtype":"afb-reply","request":{"status":"success"},"response":{"isvalid":true}}
+

Same connection check using curl:

+
$ curl http://localhost:1234/api/auth/check?token=e83b36f8-d945-463d-b983-5d8ed73ba529\&uuid=5fcc3f3d-4b84-4fc7-ba66-2d8bd34ae7d1
+{"jtype":"afb-reply","request":{"status":"success"},"response":{"isvalid":true}}
+

Format of replies

+

Replies use javascript object returned as serialized JSON.

+

This object contains at least 2 mandatory fields of name jtype and request and one optional field of name response.

+

Template

+

This is a template of replies:

+
{
+   "jtype": "afb-reply",
+   "request": {
+      "status": "success",
+      "info": "informationnal text",
+      "token": "e83b36f8-d945-463d-b983-5d8ed73ba52",
+      "uuid": "5fcc3f3d-4b84-4fc7-ba66-2d8bd34ae7d1",
+      "reqid": "application-generated-id-23456"
+   },
+   "response": ....any response object....
+}
+

Field jtype

+

The field jtype must have a value of type string equal to "afb-reply".

+

Field request

+

The field request must have a value of type object. This request object has at least one field named status and four optional fields named info, token, uuid, reqid.

+

Subfield request.status

+

status must have a value of type string. This string is equal to "success" only in case of success.

+

Subfield request.info

+

info is of type string and represent optional information added to the reply.

+

Subfield request.token

+

token is of type string. It is sent either at session creation or when the token is refreshed.

+

Subfield request.uuid

+

uuid is of type string. It is sent at session creation.

+

Subfield request.reqid

+

reqid is of type string. It is sent in response to HTTP requests that added a parameter of name reqid or x-afb-reqid at request time. Value returns in the reply has the exact same value as the one received in the request.

+

Field response

+

This field response optionally contains an object returned when request succeeded.

+

Format of events

+

Events are javascript object serialized as JSON.

+

This object contains at least 2 mandatory fields of name jtype and event and one optional field of name data.

+

Template

+

Here is a template of event:

+
{
+   "jtype": "afb-event",
+   "event": "sample_api_name/sample_event_name",
+   "data": ...any event data...
+}
+

Field jtype

+

The field jtype must have a value of type string equal to "afb-event".

+

Field event

+

The field event carries the event's name.

+

The name of the event is made of two parts separated by a slash: the name of the name of the API that generated the event and the name of event within the API.

+

Field data

+

This field data if present holds the data carried by the event.