Francois Berder
Server that executes RPC commands through HTTP.
Dependencies: EthernetInterface mbed-rpc mbed-rtos mbed
Import programHTTP-Server
Server that executes RPC commands through HTTP.
Last commit 18 Jul 2013 by 
Francois Berder
Overview
This program is a small HTTP Server that can execute RPC commands sent through HTTP and sends back a reply. This reply can be either a line of text or an HTML page.
HTTP Request
The server will only read the first line of the HTTP header. It does not check that the header is correct and it does not attempt to read the body. Hence, the server is only interested in the type of the request and the path. Instead of requesting a file, the path contains the RPC command.
RPC command encoding
Information
The RPC command must be encoded in a special way because no spaces are allowed in the path.
Thus, the RPC command is encoded in this way :
/<obj name or type>/<func name>?arg1_name=arg1_val&arg2_name=arg2_val
or, if the RPC command does not have any arguments :
/<obj name or type>/<func name>
So, a complete URL might be :
http://10.2.200.116/led2/write?val=1
The name of the arguments does not appear in the final RPC command. So these 3 urls will do exactly the same thing :
http://10.2.200.116/led2/write?val=1 http://10.2.200.116/led2/write?test=1 http://10.2.200.116/led2/write?blabla=1
Also, the order of the arguments are preserved.
Request handlers
To process requests, the server relies on RequestHandler. Each RequestHandler is assigned to a request type. Each type of request is assigned to a certain role :
- PUT requests to create new objects
- DELETE requests to delete objects
- GET requests to call a function of an object
However, there is a RequestHandler that accepts only GET requests but it can create/delete/call a function. This was necessary to provide an interactive web page that allows creation and deletion of objects.
Reply
The reply depends on the formatter. Currently, three formatters are available :
- The most basic one does not modify the RPC reply. Hence, if you consider sending request from python scripts, this formatter is the most appropriate one.
- A simple HTML formatter will allow the user to view the RPC reply and a list of RPC objects currently alive from a browser.
- Finally, a more complex HTML formatter creates an entire web page where the user can create and delete an object as well as calling functions on these objects.
Configure the server
The configuration of the server consists on choosing the formatter and adding one or more request handlers to the server. The main function initializes the server in order to produce HTML code and to receive data only using GET requests. If you want to use a simpler and different version of the server you can change the content of the main function (located in main.cpp) by this code :
main
RPCType::instance().register_types();
EthernetInterface eth;
eth.init();
eth.connect();
printf("IP Address is %s\n", eth.getIPAddress());
HTTPServer srv = create_simple_server();
if(!srv.init(SERVER_PORT))
{
printf("Error while initializing the server\n");
eth.disconnect();
return -1;
}
srv.run();
return 0;
However, this configuration will not work with the following examples.
Examples
I assume that the server is using the InteractiveHTMLFormatter (which should be the case if you did not make any changes).
Using a browser
Here is a quick guide how to run this program :
- Compiles this program and copies it to the mbed
- Open TeraTerm (install it if you don't have it), select serial and choose the port named "mbed Serial Port"
- Reset your mbed
- The IP address should appear in teraterm. In this example, I will use 10.2.200.116.
- Open your browser and go to http://10.2.200.116/.
- If everything is ok, you should see a webpage.
Now, let's switch on a led. First, we need to create an object to control a led :
Then, let's write an RPC command to switch on led :
Using python
This program creates and switches on led2.
Sending RPC commands over HTTP with Python
import httplib
SERVER_ADDRESS = '10.2.200.38'
h = httplib.HTTPConnection(SERVER_ADDRESS)
h.request("GET", "/DigitalOut/new?arg=LED2&name=led2")
r = h.getresponse()
print r.read()
h.request("GET", "/led2/write?arg=1")
r = h.getresponse()
print r.read()
h.close()
Of course, you might have to change the server address in order to make it work.
Revision 5:8ab27ca793cd, committed 2013-07-17
- Comitter:
- feb11
- Date:
- Wed Jul 17 15:01:05 2013 +0000
- Parent:
- 4:624527ebc0fa
- Child:
- 6:d03e189ebbfe
- Commit message:
- Fixed bug in InteractiveHTMLFormatter
Changed in this revision
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/Formatter.h Wed Jul 17 15:01:05 2013 +0000
@@ -0,0 +1,48 @@
+#ifndef FORMATTER
+#define FORMATTER
+
+
+class Formatter
+{
+ public :
+
+ Formatter(int nbChunk = 1);
+
+ char* get_page(char *reply);
+
+ protected :
+
+ virtual void get_chunk(const int c, char *reply);
+
+ private :
+
+ int currentChunk;
+ int nbChunk;
+};
+
+class SimpleHTMLFormatter : public Formatter
+{
+ public :
+
+ SimpleHTMLFormatter();
+
+ protected :
+
+ virtual void get_chunk(const int c, char *reply);
+
+};
+
+class InteractiveHTMLFormatter : public Formatter
+{
+ public :
+
+ InteractiveHTMLFormatter();
+
+ protected :
+
+ virtual void get_chunk(const int c, char *reply);
+};
+
+
+#endif
+
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/HTTPServer.h Wed Jul 17 15:01:05 2013 +0000
@@ -0,0 +1,39 @@
+#ifndef HTTP_SERVER
+#define HTTP_SERVER
+
+#include <map>
+
+#include "mbed.h"
+#include "mbed_rpc.h"
+#include "RequestHandler.h"
+#include "Formatter.h"
+#include "EthernetInterface.h"
+#include "RPCCommand.h"
+
+
+class HTTPServer
+{
+ public :
+
+ HTTPServer(Formatter *f = new Formatter());
+ virtual ~HTTPServer();
+
+ bool init(int port);
+
+ void run();
+
+ void add_request_handler(char *name, RequestHandler* handler);
+
+ private :
+
+ void handle_request(char *buffer);
+
+ TCPSocketServer socket;
+ std::map<char*, RequestHandler*, bool(*)(char*, char*)> handlers;
+ Formatter *formatter;
+ char reply[RPC_MAX_STRING];
+ RPCCommand command;
+};
+
+#endif
+
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/RPCCommand.cpp Wed Jul 17 15:01:05 2013 +0000
@@ -0,0 +1,130 @@
+#include "RPCCommand.h"
+#include "mbed.h"
+#include "RPCType.h"
+
+
+RPCCommand::RPCCommand():
+cmd(),
+obj_name(NULL),
+func_name(NULL)
+{
+
+}
+
+bool RPCCommand::decode(char *buffer)
+{
+ if(buffer == NULL)
+ return false;
+ if(buffer[0] != '/')
+ return false;
+
+ ++buffer;
+ char *tmp = strchr(buffer ,'/');
+
+ if(tmp == NULL)
+ return false;
+ if(tmp == buffer)
+ return false;
+
+ tmp[0] = '\0';
+ obj_name = buffer;
+
+ buffer = tmp+1;
+
+ if(buffer[0] == '\0' || buffer[0] == '?')
+ return false;
+
+ func_name = buffer;
+
+ tmp = strchr(buffer, '?');
+ if(tmp != NULL)
+ {
+ if(tmp[1] == '\0')
+ return false;
+ tmp[0] = '\0';
+ }
+
+ cmd[0] = '\0';
+ strcat(cmd, "/");
+ strcat(cmd, obj_name);
+ strcat(cmd, "/");
+ strcat(cmd, func_name);
+
+ if(tmp == NULL)
+ return true;
+
+ buffer = tmp+1;
+ do
+ {
+ tmp = strchr(buffer, '&');
+
+ if(tmp != NULL)
+ {
+ if(tmp[1] == '\0' || buffer == tmp)
+ return false;
+ tmp[0] = '\0';
+ }
+
+ char *sep = strchr(buffer, '=');
+ if(sep == NULL)
+ return false;
+ if(sep == buffer)
+ return false;
+ if(sep[1] == '\0' || sep[1] == '&')
+ return false;
+
+ strcat(cmd, " ");
+ strcat(cmd, sep+1);
+
+ if(tmp != NULL)
+ buffer = tmp+1;
+ else
+ buffer = NULL;
+ }while(buffer);
+
+ return true;
+}
+
+
+
+char* RPCCommand::get_cmd() const
+{
+ return (char*)cmd;
+}
+
+RPC_COMMAND_TYPE RPCCommand::get_type() const
+{
+ if(!strcmp(func_name, "new") && RPCType::instance().is_supported_type(obj_name))
+ return CREATE;
+
+ RPC* r = RPC::lookup(obj_name);
+ if(r == NULL)
+ return INVALID;
+
+ if(!strcmp(func_name, "delete"))
+ return DELETE;
+
+ const struct rpc_method *methods = r->get_rpc_methods();
+ int i = 0;
+ while(methods[i].name != NULL)
+ {
+ if(!strcmp(func_name, methods[i].name))
+ {
+ return FUNCTION_CALL;
+ }
+ ++i;
+ }
+
+ return INVALID;
+}
+
+char* RPCCommand::get_obj_name() const
+{
+ return obj_name;
+}
+
+char* RPCCommand::get_func_name() const
+{
+ return func_name;
+}
+
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/RPCCommand.h Wed Jul 17 15:01:05 2013 +0000
@@ -0,0 +1,36 @@
+#ifndef RPCCOMMAND
+#define RPCCOMMAND
+
+#include <list>
+#include "mbed_rpc.h"
+
+enum RPC_COMMAND_TYPE { INVALID, CREATE, DELETE, FUNCTION_CALL };
+
+struct rpc_arg
+{
+ char *name;
+ char *val;
+};
+
+class RPCCommand
+{
+ public :
+
+ RPCCommand();
+
+ bool decode(char *buffer);
+
+ char* get_cmd() const;
+ RPC_COMMAND_TYPE get_type() const;
+ char* get_obj_name() const;
+ char* get_func_name() const;
+
+ private :
+
+ char cmd[RPC_MAX_STRING];
+ char* obj_name;
+ char* func_name;
+};
+
+#endif
+
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/RPCObjectManager.cpp Wed Jul 17 15:01:05 2013 +0000
@@ -0,0 +1,68 @@
+#include "RPCObjectManager.h"
+#include "mbed.h"
+
+RPCObjectManager& RPCObjectManager::instance()
+{
+ static RPCObjectManager om;
+ return om;
+}
+
+RPCObjectManager::RPCObjectManager():
+objects()
+{
+}
+
+RPCObjectManager::~RPCObjectManager()
+{
+ for(std::list<char*>::iterator itor = objects.begin();
+ itor != objects.end();
+ ++itor)
+ delete *itor;
+}
+
+void RPCObjectManager::store_object(char *obj_name)
+{
+ char *obj = new char[strlen(obj_name)+1];
+ strcpy(obj, obj_name);
+ obj[strlen(obj_name)] = '\0';
+ objects.push_back(obj);
+}
+
+void RPCObjectManager::remove_object(char *obj_name)
+{
+ for(std::list<char*>::iterator itor = objects.begin();
+ itor != objects.end();
+ ++itor)
+ if(!strcmp(obj_name, *itor))
+ {
+ delete *itor;
+ objects.erase(itor);
+ break;
+ }
+}
+
+bool RPCObjectManager::lookup_object(char *obj_name)
+{
+ for(std::list<char*>::iterator itor = objects.begin();
+ itor != objects.end();
+ ++itor)
+ if(!strcmp(obj_name, *itor))
+ return true;
+ return false;
+}
+
+bool RPCObjectManager::is_empty()
+{
+ return objects.empty();
+}
+
+std::list<char*>::iterator RPCObjectManager::begin()
+{
+ return objects.begin();
+}
+
+std::list<char*>::iterator RPCObjectManager::end()
+{
+ return objects.end();
+}
+
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/RPCObjectManager.h Wed Jul 17 15:01:05 2013 +0000
@@ -0,0 +1,29 @@
+#ifndef RPCOBJECTMANAGER
+#define RPCOBJECTMANAGER
+
+#include <list>
+
+class RPCObjectManager
+{
+ public :
+
+ static RPCObjectManager& instance();
+
+ void store_object(char *obj_name);
+ void remove_object(char *obj_name);
+ bool lookup_object(char *obj_name);
+
+ std::list<char*>::iterator begin();
+ std::list<char*>::iterator end();
+
+ bool is_empty();
+
+ private :
+
+ RPCObjectManager();
+ ~RPCObjectManager();
+
+ std::list<char*> objects;
+};
+#endif
+
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/RPCType.cpp Wed Jul 17 15:01:05 2013 +0000
@@ -0,0 +1,55 @@
+#include "mbed.h"
+#include "mbed_rpc.h"
+#include "RPCType.h"
+
+
+RPCType::RPCType():
+supported_types()
+{
+}
+
+RPCType& RPCType::instance()
+{
+ static RPCType t;
+ return t;
+}
+
+void RPCType::register_types()
+{
+ RPCType &t = instance();
+
+ RPC::add_rpc_class<RpcDigitalOut>();
+ t.supported_types.push_back("DigitalOut");
+ RPC::add_rpc_class<RpcDigitalIn>();
+ t.supported_types.push_back("DigitalIn");
+ RPC::add_rpc_class<RpcDigitalInOut>();
+ t.supported_types.push_back("DigitalInOut");
+
+ #if DEVICE_PWMOUT
+ RPC::add_rpc_class<RpcPwmOut>();
+ t.supported_types.push_back("PwmOut");
+ #endif
+ #if DEVICE_SPI
+ t.supported_types.push_back("SPI");
+ RPC::add_rpc_class<RpcSPI>();
+ #endif
+ #if DEVICE_SERIAL
+ t.supported_types.push_back("Serial");
+ RPC::add_rpc_class<RpcSerial>();
+ #endif
+ RPC::add_rpc_class<RpcTimer>();
+ t.supported_types.push_back("Timer");
+}
+
+bool RPCType::is_supported_type(char *type)
+{
+ for(std::list<char*>::iterator itor = instance().supported_types.begin();
+ itor != instance().supported_types.end();
+ ++itor)
+ if(!strcmp(*itor,type))
+ return true;
+
+ return false;
+}
+
+
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/RPCType.h Wed Jul 17 15:01:05 2013 +0000
@@ -0,0 +1,23 @@
+#ifndef RPCTYPE_H
+#define RPCTYPE_H
+
+#include <list>
+
+class RPCType
+{
+ public :
+
+ static RPCType& instance();
+
+ void register_types();
+
+ bool is_supported_type(char *type);
+
+ private :
+
+ RPCType();
+ std::list<char*> supported_types;
+};
+
+#endif
+
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/RequestHandler.cpp Wed Jul 17 15:01:05 2013 +0000
@@ -0,0 +1,91 @@
+#include "RequestHandler.h"
+#include "mbed_rpc.h"
+#include "RPCObjectManager.h"
+#include "RPCCommand.h"
+
+void GetRequestHandler::handle(const RPCCommand& cmd, char *reply)
+{
+ switch(cmd.get_type())
+ {
+ case DELETE:
+ strcat(reply, "You must send a DELETE request to remove an object ");
+ break;
+ case FUNCTION_CALL:
+ RPC::call(cmd.get_cmd(), reply);
+ break;
+ case CREATE:
+ strcat(reply, "You must send a PUT request to call a function");
+ break;
+ default:
+ strcat(reply, "Invalid RPC command");
+ break;
+ }
+}
+
+void PutRequestHandler::handle(const RPCCommand& cmd, char *reply)
+{
+ switch(cmd.get_type())
+ {
+ case DELETE:
+ strcat(reply, "You must send a DELETE request to remove an object ");
+ break;
+ case FUNCTION_CALL:
+ strcat(reply, "You must send a GET request to call a function");
+ break;
+ case CREATE:
+ RPC::call(cmd.get_cmd(), reply);
+ if(strlen(reply) > 0)
+ {
+ RPCObjectManager::instance().store_object(reply);
+ strcat(reply, " has been created");
+ }
+ else
+ strcat(reply, "Error while creating object.");
+ break;
+ default:
+ strcat(reply, "Invalid RPC command");
+ break;
+ }
+}
+
+void DeleteRequestHandler::handle(const RPCCommand& cmd, char *reply)
+{
+ switch(cmd.get_type())
+ {
+ case CREATE:
+ strcat(reply, "You must send a PUT request to remove an object ");
+ break;
+ case FUNCTION_CALL:
+ strcat(reply, "You must send a GET request to call a function");
+ break;
+ case DELETE:
+ RPC::call(cmd.get_cmd(), reply);
+ RPCObjectManager::instance().remove_object(cmd.get_obj_name());
+ strcat(reply, "Deleted object ");
+ strcat(reply, cmd.get_obj_name());
+ break;
+ default:
+ strcat(reply, "Invalid RPC command");
+ break;
+ }
+}
+
+void ComplexRequestHandler::handle(const RPCCommand& cmd, char *reply)
+{
+ switch(cmd.get_type())
+ {
+ case CREATE :
+ putHandler.handle(cmd, reply);
+ break;
+ case DELETE :
+ deleteHandler.handle(cmd, reply);
+ break;
+ case FUNCTION_CALL :
+ getHandler.handle(cmd, reply);
+ break;
+ default :
+ strcat(reply, "Invalid RPC command");
+ break;
+ }
+}
+
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/RequestHandler.h Wed Jul 17 15:01:05 2013 +0000
@@ -0,0 +1,51 @@
+#ifndef REQUEST_HANDLER
+#define REQUEST_HANDLER
+
+#include "RPCCommand.h"
+
+class RequestHandler
+{
+ public :
+
+ virtual void handle(const RPCCommand& cmd, char* reply) = 0;
+};
+
+class GetRequestHandler : public RequestHandler
+{
+ public :
+
+ virtual void handle(const RPCCommand& cmd, char* reply);
+};
+
+class PutRequestHandler : public RequestHandler
+{
+ public :
+
+ virtual void handle(const RPCCommand& cmd, char* reply);
+
+};
+
+
+class DeleteRequestHandler : public RequestHandler
+{
+ public :
+
+ virtual void handle(const RPCCommand& cmd, char* reply);
+
+};
+
+class ComplexRequestHandler : public RequestHandler
+{
+ public :
+
+ virtual void handle(const RPCCommand& cmd, char* reply);
+
+ private :
+
+ GetRequestHandler getHandler;
+ PutRequestHandler putHandler;
+ DeleteRequestHandler deleteHandler;
+};
+
+#endif
+