From ebb9bd69a97516763d5d9203245ded592b825a86 Mon Sep 17 00:00:00 2001 From: jobol Date: Thu, 26 May 2016 18:12:12 +0200 Subject: [PATCH] update documentation Signed-off-by: jobol --- doc/FAQ.html | 5 +- doc/FAQ.md | 2 +- doc/README.html | 9 +- doc/afb-daemon-vocabulary.html | 41 ++-- doc/afb-daemon-vocabulary.md | 2 +- doc/doc.css | 7 + doc/updt.sh | 40 ++-- doc/writing-afb-plugins.html | 459 ++++++++++++++++++++++++++++++++++------- doc/writing-afb-plugins.md | 288 ++++++++++++++++++++++---- 9 files changed, 687 insertions(+), 166 deletions(-) diff --git a/doc/FAQ.html b/doc/FAQ.html index 4ebefaa3..2bd963bb 100644 --- a/doc/FAQ.html +++ b/doc/FAQ.html @@ -4,11 +4,10 @@ - -

Frequently Asked Question about AFB-DAEMON

version: 1
-Date:    24 mai 2016
+Date:    25 May 2016
 Author:  JosÃ© Bollo

diff --git a/doc/FAQ.md b/doc/FAQ.md index 32ef2789..76957c1f 100644 --- a/doc/FAQ.md +++ b/doc/FAQ.md @@ -1,7 +1,7 @@ Frequently Asked Question about AFB-DAEMON ========================================== version: 1 - Date: 24 mai 2016 + Date: 25 May 2016 Author: JosÃ© Bollo TABLE-OF-CONTENT-HERE diff --git a/doc/README.html b/doc/README.html index 0a7dffa8..04d68bf1 100644 --- a/doc/README.html +++ b/doc/README.html @@ -4,18 +4,15 @@ - -

Inititial Build

mkdir build cd build cmake ..

- -

Netbeans

- -

Copy nbprojet at project base

cp -r doc/nbproject.template ./nbproject

diff --git a/doc/afb-daemon-vocabulary.html b/doc/afb-daemon-vocabulary.html index b398aa33..4416db81 100644 --- a/doc/afb-daemon-vocabulary.html +++ b/doc/afb-daemon-vocabulary.html @@ -4,11 +4,10 @@ - -

Vocabulary for AFB-DAEMON

version: 1
-Date:    24 mai 2016
+Date:    25 May 2016
 Author:  JosÃ© Bollo

@@ -31,47 +30,35 @@ Author: JosÃ© Bollo

- -

Authentification

- -

Context

- -

Level of authorisation (LOA)

- -

Plugin

- -

Request

- -

Reply/Response

- -

Service

- -

Session

A session records data as

- -

Token

- -

UUID

It stand for Universal Unic IDentifier.

Its is designed to create identifier in a way that avoid has much as possible conflicts. It means that if two differents instance create a UUID, the probability that they create the same UUID is very low, near to zero.

- -

x-afb-token

- -

x-afb-uuid

diff --git a/doc/afb-daemon-vocabulary.md b/doc/afb-daemon-vocabulary.md index 7a4b6537..2531c81a 100644 --- a/doc/afb-daemon-vocabulary.md +++ b/doc/afb-daemon-vocabulary.md @@ -1,7 +1,7 @@ Vocabulary for AFB-DAEMON ========================= version: 1 - Date: 24 mai 2016 + Date: 25 May 2016 Author: JosÃ© Bollo TABLE-OF-CONTENT-HERE diff --git a/doc/doc.css b/doc/doc.css index a5c5be5c..d100bd1c 100644 --- a/doc/doc.css +++ b/doc/doc.css @@ -19,4 +19,11 @@ pre { outline: #555; } +pre:first-of-type { width: 20em; } +blockquote { + border-left: solid thick black; + background-color: #ff8; + font: bolder; + padding: 0.7em 1.5em; +} diff --git a/doc/updt.sh b/doc/updt.sh index cd978e22..af64e31e 100755 --- a/doc/updt.sh +++ b/doc/updt.sh @@ -1,9 +1,6 @@ -#!/bin/sh - -subst() { - awk -v pat="$1" -v rep="$(sed 's:\\:\\\\:g' $2)" '{gsub(pat,rep);gsub(pat,"\\&");print}' -} +#!/bin/bash +# the HTML template main=' @@ -14,18 +11,37 @@ GENERATED-MARKDOWN-HERE ' -for x in *.md; do - t=$(git log -n 1 --format=%ct $x) +# substitute the pattern $1 by the content of the file $2 +subst() { + awk -v pat="$1" -v rep="$(sed 's:\\:\\\\:g' $2)" '{gsub(pat,rep);gsub(pat,"\\&");print}' +} + +# update the date field of file $1 +updadate() { + local x=$1 + local t=$(git log -n 1 --format=%ct $x) [[ -n "$t" ]] || t=$(stat -c %Y $x) - d=$(LANG= date -d @$t +"%d %B %Y") + local d=$(LANG= date -d @$t +"%d %B %Y") sed -i "s/^$ Date: *$.*/\1$d/" $x - h=${x%%.md}.html - markdown -f toc,autolink $x > $h.toc.no - markdown -Tf toc,autolink $x > $h.toc.yes +} + +# make the html file for $1 +mkhtml() { + local x=$1 + local h=${x%%.md}.html + expand -i $x | sed 's: : :' > $h.pre + markdown -f toc,autolink $h.pre > $h.toc.no + markdown -Tf toc,autolink $h.pre > $h.toc.yes head --bytes=-$(stat -c %s $h.toc.no) $h.toc.yes > $h.toc echo "$main" | subst GENERATED-MARKDOWN-HERE $h.toc.no | subst TABLE-OF-CONTENT-HERE $h.toc > $h -# rm $h.toc* + rm $h.* +} + +# apply +for x in *.md; do + updadate $x + mkhtml $x done diff --git a/doc/writing-afb-plugins.html b/doc/writing-afb-plugins.html index 5aeca0a5..712d30ee 100644 --- a/doc/writing-afb-plugins.html +++ b/doc/writing-afb-plugins.html @@ -4,11 +4,10 @@ - -

HOWTO WRITE a PLUGIN for AFB-DAEMON

version: 1
-Date:    24 mai 2016
+Date:    25 May 2016
 Author:  JosÃ© Bollo

@@ -18,6 +17,12 @@ Author: JosÃ© Bollo

Summary

Nature of a plugin
Kinds of plugins +
- Application plugins
- Service plugins
+
Live cycle of a plugin within afb-daemon
Content of a plugin
- Writing a synchronous verb implementation
- Getting argument of invocation
- Getting argument of invocation +
  +
- Sending messages to the log system
- How to build a plugin

- -

Summary

The binder afb-daemon serves files through the HTTP protocol and offers access to API’s through @@ -69,8 +80,7 @@ by developpers.

Before going into details, through a tiny example, a short overview plugins basis is needed.

- -

Nature of a plugin

A plugin is a separate piece of code made of a shared library. The plugin is loaded and activated by afb-daemon when afb-daemon @@ -78,8 +88,33 @@ starts.

Technically, a plugin is not linked to any library of afb-daemon.

- -

Live cycle of a plugin within afb-daemon

Kinds of plugins

+ +

There is two kinds of plugins: application plugins and service +plugins.

+ +

Application plugins

+ +

Application plugins are intended to be instanciated for each +application: when an application using that plugin is started, +its binder starts a new instance of the plugin.

+ +

It means that the application plugins mainly have only one +context to manage for one client.

+ +

Service plugins

+ +

Service plugins are intended to be instanciated only one time +only and connected to many clients.

+ +

So either it does not manage context at all or otherwise, +if it manages context, it should be able to manage one context +per client.

+ +

In details, it may be useful to have service plugins at a user +level.

+ +

Live cycle of a plugin within afb-daemon

The plugins are loaded and activated when afb-daemon starts.

@@ -97,8 +132,7 @@ Consequently, developpers of plugins should use ‘atexit’ or ‘on_exit’ during initialisation if they need to perform specific actions when stopping.

- -

Content of a plugin

For afb-daemon, a plugin contains 2 different things: names and functions.

@@ -124,8 +158,7 @@ and upper case when searching for a method. Thus, The names TicTacToe/Board and tictactoe/borad are equals.

- -

The name of the plugin

The name of the plugin is also known as the name of the API that defines the plugin.

@@ -140,8 +173,7 @@ extracts the prefix foo and the suffix bar. foo is the API name and must match a plugin name, the plugin that implements the verb bar.

- -

Names of verbs

Each plugin exposes a set of verbs that can be called by client of afb-daemon.

@@ -154,8 +186,7 @@ when clients emit requests for that verb.

For example, when a client of afb-daemon calls a method named foo/bar.

- -

The initialisation function

The initialisation function serves several purposes.

@@ -171,8 +202,7 @@ requirements and implmentations of the verbs that it exposes.

- -

Functions implementing verbs

When a method is called, afb-daemon constructs a request object and pass it to the implementation function for verb @@ -198,8 +228,7 @@ returning are named asynchronous implementations.

asynchronous action and record to send the reply on completion of this action.

- -

The Tic-Tac-Toe example

This part explains how to write an afb-plugin. For the sake of being practical we will use many @@ -208,8 +237,7 @@ This plugin example is in plugins/samples/tic-tac-toe.c.

This plugin is named tictactoe.

- -

Choosing names

The designer of a plugin must defines names for its plugin (or its API) and for the verbs of its API. He also @@ -221,8 +249,7 @@ the names easy to use across plaforms.

The names and strings used ALL are UTF-8 encoded.

- -

Names for API (plugin)

The names of the API are checked. All characters are authorised except:

@@ -241,8 +268,7 @@ All characters are authorised except:

Afb-daemon make no distinction between lower case and upper case when searching for an API by its name.

- -

Names for verbs

The names of the verbs are not checked.

@@ -253,8 +279,7 @@ is forbidden.

Afb-daemon make no distinction between lower case and upper case when searching for an API by its name.

- -

Names for arguments

The names for arguments are not restricted and can be anything.

@@ -263,8 +288,7 @@ anything.

string comparison. Thus the names “index” and “Index” are not the same.

- -

Forging names widely available

The key names of javascript object can be almost anything using the arrayed notation:

@@ -287,8 +311,7 @@ valid javascript identifier.

rely on the case sensitivity and to avoid the use of names different only by the case.

- -

Options to set when compiling plugins

Afb-daemon provides a configuration file for pkg-config. Typing the command

@@ -313,8 +336,7 @@ This is done through the Requires keyword of pkg-config.

If this behaviour is a problem, let us know.

- -

Header files to include

The plugin tictactoe has the following lines for its includes:

@@ -341,8 +363,7 @@ if it needs it:

When including afb/afb-plugin.h, the macro _GNU_SOURCE must be defined.

- -

Writing a synchronous verb implementation

The verb tictactoe/board is a synchronous implementation. Here is its listing:

@@ -352,33 +373,61 @@ Here is its listing:

*/ static void board(struct afb_req req) { - struct board *board; - struct json_object *description; + struct board *board; + struct json_object *description; - /* retrieves the context for the session */ - board = board_of_req(req); - INFO(afbitf, "method 'board' called for boardid %d", board->id); + /* retrieves the context for the session */ + board = board_of_req(req); + INFO(afbitf, "method 'board' called for boardid %d", board->id); - /* describe the board */ - description = describe(board); + /* describe the board */ + description = describe(board); - /* send the board's description */ - afb_req_success(req, description, NULL); + /* send the board's description */ + afb_req_success(req, description, NULL); }

This examples show many aspects of writing a synchronous -verb implementation.

+verb implementation. Let summarize it:

- -

The incoming request

The function board_of_req retrieves the context stored +for the plugin: the board.
The macro INFO sends a message of kind INFO +to the logging system. The global variable named afbitf +used represents the interface to afb-daemon.
The function describe creates a json_object representing +the board.
The function afb_req_success sends the reply, attaching to +it the object description.

+ + +

The incoming request

For any implementation, the request is received by a structure of type +

For any implementation, the request is received by a structure of type struct afb_req.

Important: note that this is a PLAIN structure, not a pointer to a structure.

Note that this is a PLAIN structure, not a pointer to a structure.

+ +

The definition of struct afb_req is:

+ +

/*
+ * Describes the request by plugins from afb-daemon
+ */
+struct afb_req {
+        const struct afb_req_itf *itf;  /* the interfacing functions */
+        void *closure;          /* the closure for functions */
+};
+

+ +

It contains two pointers: one, itf, points to the functions needed +to handle the internal request represented by the second pointer, closure.

This structure, here named req, is used

The structure must never be used directly. +Insted, use the intended functions provided +by afb-daemon and described here.

req is used to get arguments of the request, to send answer, to store session data.

@@ -394,8 +443,7 @@ the session of the request.

The second time, it is used to send the reply: an object that describes the current board.

- -

Associating an object to the session for the plugin

Associating a context to the session

When the plugin tic-tac-toe receives a request, it musts regain the board that describes the game associated to the session.

@@ -430,14 +478,14 @@ its context: the board. This function is board_of_req:

*/ static inline struct board *board_of_req(struct afb_req req) { - return afb_req_context(req, (void*)get_new_board, (void*)release_board); + return afb_req_context(req, (void*)get_new_board, (void*)release_board); } -

This function is very simple because it merely wraps -a call to the function afb_req_context, providing -all needed arguments. -The casts are required to avoid a warning when compiling.

The function afb_req_context ensure an existing context +for the session of the request. +Its two last arguments are functions. Here, the casts are required +to avoid a warning when compiling.

Here is the definition of the function afb_req_context

@@ -450,33 +498,286 @@ The casts are required to avoid a warning when compiling.

*/ static inline void *afb_req_context(struct afb_req req, void *(*create_context)(), void (*free_context)(void*)) { - void *result = afb_req_context_get(req); - if (result == NULL) { - result = create_context(); - afb_req_context_set(req, result, free_context); - } - return result; + void *result = afb_req_context_get(req); + if (result == NULL) { + result = create_context(); + afb_req_context_set(req, result, free_context); + } + return result; } -

This powerful function ensures that the context exists and is -stored for the session.

- -

The function get_new_board creates a new board and set its +

The second argument if the function that creates the context. +For the plugin tic-tac-toe it is the function get_new_board. +The function get_new_board creates a new board and set its count of use to 1. The boards are counting their count of use to free there ressources when no more used.

The function release_board

The third argument if the function that frees the context. +For the plugin tic-tac-toe it is the function release_board. +The function release_board decrease the the count of use of +the board given as argument. If the use count decrease to zero, +the board data are freed.

+ +

The definition of the other functions for dealing with contexts are:

+ +

/*
+ * Gets the pointer stored by the plugin for the session of 'req'.
+ * When the plugin has not yet recorded a pointer, NULL is returned.
+ */
+void *afb_req_context_get(struct afb_req req);
+
+/*
+ * Stores for the plugin the pointer 'context' to the session of 'req'.
+ * The function 'free_context' will be called when the session is closed
+ * or if plugin stores an other pointer.
+ */
+void afb_req_context_set(struct afb_req req, void *context, void (*free_context)(void*));
+
+/*
+ * Frees the pointer stored by the plugin for the session of 'req'
+ * and sets it to NULL.
+ *
+ * Shortcut for: afb_req_context_set(req, NULL, NULL)
+ */
+static inline void afb_req_context_clear(struct afb_req req)
+{
+        afb_req_context_set(req, NULL, NULL);
+}
+

+ +

Sending the reply to a request

+ +

Two kinds of replies can be made: successful replies and +failure replies.

+ +

Sending a reply to a request must be done at most one time.

+ +

The two functions to send a reply of kind “success” are +afb_req_success and afb_req_success_f.

+ +

/*
+ * Sends a reply of kind success to the request 'req'.
+ * The status of the reply is automatically set to "success".
+ * Its send the object 'obj' (can be NULL) with an
+ * informationnal comment 'info (can also be NULL).
+ */
+void afb_req_success(struct afb_req req, struct json_object *obj, const char *info);
+
+/*
+ * Same as 'afb_req_success' but the 'info' is a formatting
+ * string followed by arguments.
+ */
+void afb_req_success_f(struct afb_req req, struct json_object *obj, const char *info, ...);
+

+ +

The two functions to send a reply of kind “failure” are +afb_req_fail and afb_req_fail_f.

+ +

/*
+ * Sends a reply of kind failure to the request 'req'.
+ * The status of the reply is set to 'status' and an
+ * informationnal comment 'info' (can also be NULL) can be added.
+ *
+ * Note that calling afb_req_fail("success", info) is equivalent
+ * to call afb_req_success(NULL, info). Thus even if possible it
+ * is strongly recommanded to NEVER use "success" for status.
+ */
+void afb_req_fail(struct afb_req req, const char *status, const char *info);
+
+/*
+ * Same as 'afb_req_fail' but the 'info' is a formatting
+ * string followed by arguments.
+ */
+void afb_req_fail_f(struct afb_req req, const char *status, const char *info, ...);
+

+ +

Getting argument of invocation

+ +

Many verbs expect arguments. Afb-daemon let plugins +retrieve their arguments by name not by position.

+ +

Arguments are given by the requests either through HTTP +or through WebSockets.

+ +

For example, the verb join of the plugin tic-tac-toe +expects one argument: the boardid to join. Here is an extract:

+ +

/*
+ * Join a board
+ */
+static void join(struct afb_req req)
+{
+        struct board *board, *new_board;
+        const char *id;
+
+        /* retrieves the context for the session */
+        board = board_of_req(req);
+        INFO(afbitf, "method 'join' called for boardid %d", board->id);
+
+        /* retrieves the argument */
+        id = afb_req_value(req, "boardid");
+        if (id == NULL)
+                goto bad_request;
+        ...
+

+ +

The function afb_req_value search in the request req +for an argument whose name is given. When no argument of the +given name was passed, afb_req_value returns NULL.

+ +

The search is case sensitive. So the name boardid is not the +same name than BoardId. But this must not be assumed so two +expected names of argument should not differ only by case.

+ +

Basic functions for querying arguments

+ +

The function afb_req_value is defined as below:

+ +

/*
+ * Gets from the request 'req' the string value of the argument of 'name'.
+ * Returns NULL if when there is no argument of 'name'.
+ * Returns the value of the argument of 'name' otherwise.
+ *
+ * Shortcut for: afb_req_get(req, name).value
+ */
+static inline const char *afb_req_value(struct afb_req req, const char *name)
+{
+        return afb_req_get(req, name).value;
+}
+

+ +

It is defined as a shortcut to call the function afb_req_get. +That function is defined as below:

+ +

/*
+ * Gets from the request 'req' the argument of 'name'.
+ * Returns a PLAIN structure of type 'struct afb_arg'.
+ * When the argument of 'name' is not found, all fields of result are set to NULL.
+ * When the argument of 'name' is found, the fields are filled,
+ * in particular, the field 'result.name' is set to 'name'.
+ *
+ * There is a special name value: the empty string.
+ * The argument of name "" is defined only if the request was made using
+ * an HTTP POST of Content-Type "application/json". In that case, the
+ * argument of name "" receives the value of the body of the HTTP request.
+ */
+struct afb_arg afb_req_get(struct afb_req req, const char *name);
+

+ +

That function takes 2 parameters: the request and the name +of the argument to retrieve. It returns a PLAIN structure of +type struct afb_arg.

+ +

There is a special name that is defined when the request is +of type HTTP/POST with a Content-Type being application/json. +This name is “” (the empty string). In that case, the value +of this argument of empty name is the string received as a body +of the post and is supposed to be a JSON string.

+ +

The definition of struct afb_arg is:

+ +

/*
+ * Describes an argument (or parameter) of a request
+ */
+struct afb_arg {
+        const char *name;   /* name of the argument or NULL if invalid */
+        const char *value;  /* string representation of the value of the argument */
+                                /* original filename of the argument if path != NULL */
+        const char *path;   /* if not NULL, path of the received file for the argument */
+                                /* when the request is finalized this file is removed */
+};
+

+ +

The structure returns the data arguments that are known for the +request. This data include a field named path. This path +can be accessed using the function afb_req_path defined as +below:

+ +

/*
+ * Gets from the request 'req' the path for file attached to the argument of 'name'.
+ * Returns NULL if when there is no argument of 'name' or when there is no file.
+ * Returns the path of the argument of 'name' otherwise.
+ *
+ * Shortcut for: afb_req_get(req, name).path
+ */
+static inline const char *afb_req_path(struct afb_req req, const char *name)
+{
+        return afb_req_get(req, name).path;
+}
+

+ +

The path is only defined for HTTP/POST requests that send file.

+ +

Arguments for received files

+ +

As it is explained just above, clients can send files using +HTTP/POST requests.

+ +

Received files are attached to a arguments. For example, the +following HTTP fragment (from test/sample-post.html) +will send an HTTP/POST request to the method +post/upload-image with 2 arguments named file and +hidden.

+ +

<h2>Sample Post File</h2>
+<form enctype="multipart/form-data">
+    <input type="file" name="file" />
+    <input type="hidden" name="hidden" value="bollobollo" />
+    <br>
+    <button formmethod="POST" formaction="api/post/upload-image">Post File</button>
+</form>
+

+ +

In that case, the argument named file has its value and its +path defined and not NULL.

+ +

The value is the name of the file as it was +set by the HTTP client and is generally the filename on the +client side.

+ +

The path is the path of the file saved on the temporary local storage +area of the application. This is a randomly generated and unic filename +not linked in any way with the original filename on the client.

+ +

The plugin can use the file at the given path the way that it wants: +read, write, remove, copy, rename… +But when the reply is sent and the query is terminated, the file at +this path is destroyed if it still exist.

+ +

Arguments as a JSON object

+ +

Plugins can get all the arguments as one single object. +This feature is provided by the function afb_req_json +that is defined as below:

+ +

/*
+ * Gets from the request 'req' the json object hashing the arguments.
+ * The returned object must not be released using 'json_object_put'.
+ */
+struct json_object *afb_req_json(struct afb_req req);
+

+ +

It returns a json object. This object depends on how the request was +made:

+ +

For HTTP requests, this is an object whose keys are the names of the +arguments and whose values are either a string for common arguments or +an object like { “file”: “…”, “path”: “…” }
For WebSockets requests, the returned object is the object +given by the client transparently transported.

+ - -

Sending the reply to a request

In fact, for Websockets requests, the function afb_req_value +can be seen as a shortcut to +json_object_get_string(json_object_object_get(afb_req_json(req), name))

- -

Getting argument of invocation

Sending messages to the log system

- -

How to build a plugin

Afb-daemon provides a The packaging of afb-daemon

Afb-daemon provides a pkg-config configuration file.

diff --git a/doc/writing-afb-plugins.md b/doc/writing-afb-plugins.md index ba2e676a..7611600f 100644 --- a/doc/writing-afb-plugins.md +++ b/doc/writing-afb-plugins.md @@ -28,6 +28,32 @@ The plugin is loaded and activated by afb-daemon when afb-daemon starts. Technically, a plugin is not linked to any library of afb-daemon. + +### Kinds of plugins + +There is two kinds of plugins: application plugins and service +plugins. + +#### Application plugins + +Application plugins are intended to be instanciated for each +application: when an application using that plugin is started, +its binder starts a new instance of the plugin. + +It means that the application plugins mainly have only one +context to manage for one client. + +#### Service plugins + +Service plugins are intended to be instanciated only one time +only and connected to many clients. + +So either it does not manage context at all or otherwise, +if it manages context, it should be able to manage one context +per client. + +In details, it may be useful to have service plugins at a user +level. ### Live cycle of a plugin within afb-daemon @@ -312,12 +338,27 @@ it the object *description*. ### The incoming request -For any implementation, the request is received by a structure of type +For any implementation, the request is received by a structure of type **struct afb_req**. -***Important: note that this is a PLAIN structure, not a pointer to a structure.*** +> Note that this is a PLAIN structure, not a pointer to a structure. + +The definition of **struct afb_req** is: + + /* + * Describes the request by plugins from afb-daemon + */ + struct afb_req { + const struct afb_req_itf *itf; /* the interfacing functions */ + void *closure; /* the closure for functions */ + }; + +It contains two pointers: one, *itf*, points to the functions needed +to handle the internal request represented by the second pointer, *closure*. -This structure, here named *req*, is used +> The structure must never be used directly. +> Insted, use the intended functions provided +> by afb-daemon and described here. *req* is used to get arguments of the request, to send answer, to store session data. @@ -333,7 +374,7 @@ the session of the request. The second time, it is used to send the reply: an object that describes the current board. -### Associating an object to the session for the plugin +### Associating a context to the session When the plugin *tic-tac-toe* receives a request, it musts regain the board that describes the game associated to the session. @@ -407,14 +448,41 @@ The function **release_board** decrease the the count of use of the board given as argument. If the use count decrease to zero, the board data are freed. -### Sending the reply to a request +The definition of the other functions for dealing with contexts are: + + /* + * Gets the pointer stored by the plugin for the session of 'req'. + * When the plugin has not yet recorded a pointer, NULL is returned. + */ + void *afb_req_context_get(struct afb_req req); -Sending a reply to a request must be done at most one time. + /* + * Stores for the plugin the pointer 'context' to the session of 'req'. + * The function 'free_context' will be called when the session is closed + * or if plugin stores an other pointer. + */ + void afb_req_context_set(struct afb_req req, void *context, void (*free_context)(void*)); + + /* + * Frees the pointer stored by the plugin for the session of 'req' + * and sets it to NULL. + * + * Shortcut for: afb_req_context_set(req, NULL, NULL) + */ + static inline void afb_req_context_clear(struct afb_req req) + { + afb_req_context_set(req, NULL, NULL); + } + +### Sending the reply to a request Two kinds of replies can be made: successful replies and failure replies. -The functions to send replies are defined as below: +> Sending a reply to a request must be done at most one time. + +The two functions to send a reply of kind "success" are +**afb_req_success** and **afb_req_success_f**. /* * Sends a reply of kind success to the request 'req'. @@ -422,26 +490,16 @@ The functions to send replies are defined as below: * Its send the object 'obj' (can be NULL) with an * informationnal comment 'info (can also be NULL). */ - static inline void afb_req_success(struct afb_req req, struct json_object *obj, const char *info) - { - req.itf->success(req.closure, obj, info); - } + void afb_req_success(struct afb_req req, struct json_object *obj, const char *info); /* * Same as 'afb_req_success' but the 'info' is a formatting * string followed by arguments. */ - static inline void afb_req_success_f(struct afb_req req, struct json_object *obj, const char *info, ...) - { - char *message; - va_list args; - va_start(args, info); - if (info == NULL || vasprintf(&message, info, args) < 0) - message = NULL; - va_end(args); - afb_req_success(req, obj, message); - free(message); - } + void afb_req_success_f(struct afb_req req, struct json_object *obj, const char *info, ...); + +The two functions to send a reply of kind "failure" are +**afb_req_fail** and **afb_req_fail_f**. /* * Sends a reply of kind failure to the request 'req'. @@ -452,31 +510,187 @@ The functions to send replies are defined as below: * to call afb_req_success(NULL, info). Thus even if possible it * is strongly recommanded to NEVER use "success" for status. */ - static inline void afb_req_fail(struct afb_req req, const char *status, const char *info) - { - req.itf->fail(req.closure, status, info); - } + void afb_req_fail(struct afb_req req, const char *status, const char *info); /* * Same as 'afb_req_fail' but the 'info' is a formatting * string followed by arguments. */ - static inline void afb_req_fail_f(struct afb_req req, const char *status, const char *info, ...) + void afb_req_fail_f(struct afb_req req, const char *status, const char *info, ...); + +Getting argument of invocation +------------------------------ + +Many verbs expect arguments. Afb-daemon let plugins +retrieve their arguments by name not by position. + +Arguments are given by the requests either through HTTP +or through WebSockets. + +For example, the verb **join** of the plugin **tic-tac-toe** +expects one argument: the *boardid* to join. Here is an extract: + + /* + * Join a board + */ + static void join(struct afb_req req) { - char *message; - va_list args; - va_start(args, info); - if (info == NULL || vasprintf(&message, info, args) < 0) - message = NULL; - va_end(args); - afb_req_fail(req, status, message); - free(message); + struct board *board, *new_board; + const char *id; + + /* retrieves the context for the session */ + board = board_of_req(req); + INFO(afbitf, "method 'join' called for boardid %d", board->id); + + /* retrieves the argument */ + id = afb_req_value(req, "boardid"); + if (id == NULL) + goto bad_request; + ... + +The function **afb_req_value** search in the request *req* +for an argument whose name is given. When no argument of the +given name was passed, **afb_req_value** returns NULL. + +> The search is case sensitive. So the name *boardid* is not the +> same name than *BoardId*. But this must not be assumed so two +> expected names of argument should not differ only by case. + +### Basic functions for querying arguments + +The function **afb_req_value** is defined as below: + + /* + * Gets from the request 'req' the string value of the argument of 'name'. + * Returns NULL if when there is no argument of 'name'. + * Returns the value of the argument of 'name' otherwise. + * + * Shortcut for: afb_req_get(req, name).value + */ + static inline const char *afb_req_value(struct afb_req req, const char *name) + { + return afb_req_get(req, name).value; } +It is defined as a shortcut to call the function **afb_req_get**. +That function is defined as below: + /* + * Gets from the request 'req' the argument of 'name'. + * Returns a PLAIN structure of type 'struct afb_arg'. + * When the argument of 'name' is not found, all fields of result are set to NULL. + * When the argument of 'name' is found, the fields are filled, + * in particular, the field 'result.name' is set to 'name'. + * + * There is a special name value: the empty string. + * The argument of name "" is defined only if the request was made using + * an HTTP POST of Content-Type "application/json". In that case, the + * argument of name "" receives the value of the body of the HTTP request. + */ + struct afb_arg afb_req_get(struct afb_req req, const char *name); -Getting argument of invocation ------------------------------- +That function takes 2 parameters: the request and the name +of the argument to retrieve. It returns a PLAIN structure of +type **struct afb_arg**. + +There is a special name that is defined when the request is +of type HTTP/POST with a Content-Type being application/json. +This name is **""** (the empty string). In that case, the value +of this argument of empty name is the string received as a body +of the post and is supposed to be a JSON string. + +The definition of **struct afb_arg** is: + + /* + * Describes an argument (or parameter) of a request + */ + struct afb_arg { + const char *name; /* name of the argument or NULL if invalid */ + const char *value; /* string representation of the value of the argument */ + /* original filename of the argument if path != NULL */ + const char *path; /* if not NULL, path of the received file for the argument */ + /* when the request is finalized this file is removed */ + }; + +The structure returns the data arguments that are known for the +request. This data include a field named **path**. This **path** +can be accessed using the function **afb_req_path** defined as +below: + + /* + * Gets from the request 'req' the path for file attached to the argument of 'name'. + * Returns NULL if when there is no argument of 'name' or when there is no file. + * Returns the path of the argument of 'name' otherwise. + * + * Shortcut for: afb_req_get(req, name).path + */ + static inline const char *afb_req_path(struct afb_req req, const char *name) + { + return afb_req_get(req, name).path; + } + +The path is only defined for HTTP/POST requests that send file. + +### Arguments for received files + +As it is explained just above, clients can send files using +HTTP/POST requests. + +Received files are attached to a arguments. For example, the +following HTTP fragment (from test/sample-post.html) +will send an HTTP/POST request to the method +**post/upload-image** with 2 arguments named *file* and +*hidden*. + +

Sample Post File

+ + +In that case, the argument named **file** has its value and its +path defined and not NULL. + +The value is the name of the file as it was +set by the HTTP client and is generally the filename on the +client side. + +The path is the path of the file saved on the temporary local storage +area of the application. This is a randomly generated and unic filename +not linked in any way with the original filename on the client. + +The plugin can use the file at the given path the way that it wants: +read, write, remove, copy, rename... +But when the reply is sent and the query is terminated, the file at +this path is destroyed if it still exist. + +### Arguments as a JSON object + +Plugins can get all the arguments as one single object. +This feature is provided by the function **afb_req_json** +that is defined as below: + + /* + * Gets from the request 'req' the json object hashing the arguments. + * The returned object must not be released using 'json_object_put'. + */ + struct json_object *afb_req_json(struct afb_req req); + +It returns a json object. This object depends on how the request was +made: + +- For HTTP requests, this is an object whose keys are the names of the +arguments and whose values are either a string for common arguments or +an object like { "file": "...", "path": "..." } + +- For WebSockets requests, the returned object is the object +given by the client transparently transported. + +> In fact, for Websockets requests, the function **afb_req_value** +> can be seen as a shortcut to +> *json_object_get_string(json_object_object_get(afb_req_json(req), name))* Sending messages to the log system ---------------------------------- -- 2.16.6