-
-Overview of the bindings
-========================
+# Overview of the bindings
The ***binder*** serves files through HTTP protocol and offers to
developers the capability to offer application API methods through HTTP or
WebSocket protocol.
-The ***bindings*** are used to add **API** to ***binders***.
+The ***bindings*** are used to add **API** to ***binders***.
This part describes how to write a ***binding*** for ***binder***
or in other words how to add a new **API** to the system.
using the C programming language.
It is convenient to install the ***binder*** on the
-desktop used for writing the binding. It allows easy
-debug and test.
+desktop used for writing the binding.
+It allows easy debug and test.
## Nature of a binding
A ***binding*** is an independent piece of software compiled as a shared
-library and dynamically loaded by a ***binder***.
+library and dynamically loaded by a ***binder***.
It is intended to provide one **API** (**A**pplication **P**rogramming
**I**nterface).
-The **API** is designated and accessed through its name.
+The **API** is designated and accessed through its name.
It contains several **verbs** that implement the ***binding***
-functionalities. Each of these **verbs** is a **method** that
+functionalities.
+Each of these **verbs** is a **method** that
processes requests of applications and sends result.
The ***binding***'s methods are invoked by HTTP or websocket
The **methods** of the ***bindings*** are noted **api/verb**
where **api** is the **API** name of the binding and **verb** is
-the **method**'s name within the **API**.
+the **method**'s name within the **API**.
This notation comes from HTTP invocations that rely on URL path terminated
with **api/verb**.
The name of an **API** can be made of any characters except:
- - the control characters (\u0000 .. \u001f)
- - the characters of the set { ' ', '"', '#', '%', '&',
+- the control characters (\u0000 .. \u001f)
+- the characters of the set { ' ', '"', '#', '%', '&',
'\'', '/', '?', '`', '\x7f' }
-The names if the **verbs** can be any character.
+The names of the **verbs** can be any character.
The binder makes no distinctions between upper case and lower case
-latin letters. So **API/VERB** matches **Api/Verb** or **api/verb**.
+latin letters.
+So **API/VERB** matches **Api/Verb** or **api/verb**.
Actually it exists 2 ways of writing ***bindings***.
You can either write:
- - a binding version 1 (not recommended);
- - a binding version 2 (RECOMMENDED).
+- a binding version 1 (not recommended);
+- a binding version 2 (RECOMMENDED).
-A ***binder*** loads and runs any of these version in any combination.
+A ***binder*** loads and runs any of these version in any combination.
This document explain how to write bindings version 2.
<!-- pagebreak -->
-Sample binding: tuto-1
-======================
+## Sample binding: tuto-1
This is the code of the binding **tuto-1.c**:
Compiling:
```bash
-$ gcc -fPIC -shared tuto-1.c -o tuto-1.so $(pkg-config --cflags-only-I afb-daemon)
+gcc -fPIC -shared tuto-1.c -o tuto-1.so $(pkg-config --cflags-only-I afb-daemon)
```
Running:
```bash
-$ afb-daemon --binding tuto-1.so --port 3333 --token ''
+afb-daemon --binding tuto-1.so --port 3333 --token ''
```
Testing using **curl**:
This shows basic things:
- - The include to get for creating a binding
- - How to declare the API offered by the binding
- - How to handle request made to the binding
-
+- The include to get for creating a binding
+- How to declare the API offered by the binding
+- How to handle request made to the binding
### Getting declarations for the binding
2 #include <afb/afb-binding.h>
```
-You must define the version of ***binding*** that you are using.
+You must define the version of ***binding*** that you are using.
This is done line 1 where we define that this is the version 2.
If you don't define it, a warning message is prompted by the compiler
-and the version is switched to version 1. This behaviour is
-temporarily and enables to continue to use previously written
+and the version is switched to version 1.
+This behaviour is temporarily and enables to continue to use previously written
***binding*** without change but it will change in some future when
***bindings*** V1 will become obsoletes.
Setting the include path is easy using **pkg-config**:
```bash
-$ pkg-config --cflags-only-I afb-daemon
+pkg-config --cflags-only-I afb-daemon
```
-Note for **C++** developers: The ***binder*** currently expose
-only **C** language **API**. The file **afb/afb-binding.h**
-isn't **C++** ready. You should use the construct **extern "C"**
-as below:
+Note for **C++** developers:
+
+- The ***binder*** currently expose only **C** language **API**.
+ The file **afb/afb-binding.h** isn't **C++** ready.
+
+You should use the construct **extern "C"** as below:
```C
#define AFB_BINDING_VERSION 2
```
Future version of the ***binder*** will include a **C++**
-interface. Until it is available, please, use the above
-construct.
+interface.
+Until it is available, please, use the above construct.
### Declaring the API of the binding
The structure **afbBindingV2** actually tells that:
- - the exported **API** name is **tuto-1** (line 16)
- - the array of verbs is the above defined one
+- the exported **API** name is **tuto-1** (line 16)
+- the array of verbs is the above defined one
The exported list of verb is specified by an array of structures,
each describing a verb, ended with a verb NULL (line 12).
should at the end emit a reply for the request.
Here, the callback for **tuto-1/hello** replies a successful answer
-(line 7) to the request **req**. The second parameter (here NULL)
-is a json object that is sent to the client with the reply.
+(line 7) to the request **req**.
+The second parameter (here NULL) is a json object that is sent to the client with the reply.
The third parameter is also sent with the reply and is a string
called info that can be used as some meta data.
<!-- pagebreak -->
-Sample binding: tuto-2
-======================
+## Sample binding: tuto-2
The second tutorial shows many important feature that can
-commonly be used when writing a ***binding***: initialization,
-getting arguments, sending replies, pushing events.
+commonly be used when writing a ***binding***:
+
+- initialization, getting arguments, sending replies, pushing events.
This is the code of the binding **tuto-2.c**:
Compiling:
```bash
-$ gcc -fPIC -shared tuto-2.c -o tuto-2.so $(pkg-config --cflags --libs afb-daemon)
+gcc -fPIC -shared tuto-2.c -o tuto-2.so $(pkg-config --cflags --libs afb-daemon)
```
Running:
```bash
-$ afb-daemon --binding tuto-2.so --port 3333 --token ''
+afb-daemon --binding tuto-2.so --port 3333 --token ''
```
Testing:
"jtype":"afb-event"
}
```
-
Code Review / src / app-framework-binder.git / blobdiff