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diff --git a/docs/afb-overview.md b/docs/afb-overview.md new file mode 100644 index 00000000..67e5b0d1 --- /dev/null +++ b/docs/afb-overview.md @@ -0,0 +1,98 @@ + +Overview of the binder +====================== + +The ***binder*** provides the way to connect applications to +the services that it needs. It provides a fast way +to securely offer APIs to applications written in +any language and running almost anywhere. + +The ***binder*** is developped for AGL. + +The ***binder*** is the usual name. +The binary is named **afb-daemon**. + +The name **afb-daemon** stands for ***Application +Framework Binder Daemon***. The word *daemon*, here, +denote the fact that the ***binder*** makes witchcraft to +connect applications to their expected services (note that usually +the term of daemon denotes background process but not here). + +Each ***binder*** **afb-daemon** is in charge to bind +one instance of an application or service to the rest +of the system, applications and services. +Within AGL, the connexion between services and/or +applications is tuned by the AGL framework and +the AGL system. + +The basis of the binder +======================= + +The following figure shows main concepts linked to the ***binder***. + +<a id="fig-binder-basis"></a> + + +The shown elements are: + +* The SECURITY CONTEXT + + The primary intend of any ***binder*** is to provide + a secured environment for any application. On AGL, the + **security context** is ensured by [Smack][Smack] a security context, + the security context of the application or service. + +* The BINDER + + This is the central element. It makes possible to run HTML5 + applications and provides the unified access to APIs provided + by the ***bindings***. + + Running a pure HTML5 application doesn't require any ***binding***. + in that case , the ***binder*** acts as a simple HTTP server for + the web runtime. + +* The BINDINGs + + A ***binding*** adds one **API** to the ***binder***. + + An **API** is a set of **verbs** that can be called + using either REST over HTTP or a kind of JSON RPC. + + ***bindings*** are either: + + - dynamically loaded libraries in the ***binder*** process + - remote service running on the same host + - remote service running on other hosts + + When acting as an HTTP server, the binder treats the language + settings of the HTTP resquests to provide internationalized + content as specified by + [widget specifications](https://www.w3.org/TR/widgets/#internationalization-and-localization). + +* The APPLICATION + + An ***application*** connects to the binder to get access to + the **API** that it provides or to get its HTTP services to access + resources. + +Interconnection of binders +========================== + +The AGL framework interprets the **widget/application** manifests +to setup the ***bindings*** configuration of the ***binders***. + +The figure below shows that ***binders*** are interconnected. + +<a id="fig-binder-interconnection"></a> + + +The figure shows 4 several **application/service**: **A**, **B**, +**C** and **D**. + +The application **A** might use an **API** that is shown as a +local ***binbing*** but that in reality runs within the context +of **D**. + +The framework AGL takes care of making the plumbing working. + |