AbstractClient.h

00001 /*
00002  * AbstractClient.h
00003  *
00004  * Created on: Nov 1, 2013
00005  * * Authors: Vincent Wochnik <v.wochnik@gmail.com>
00006  *
00007  * Copyright (c) 2013 Cumulocity GmbH
00008  *
00009  * Permission is hereby granted, free of charge, to any person obtaining
00010  * a copy of this software and associated documentation files (the
00011  * "Software"), to deal in the Software without restriction, including
00012  * without limitation the rights to use, copy, modify, merge, publish,
00013  * distribute, sublicense, and/or sell copies of the Software, and to
00014  * permit persons to whom the Software is furnished to do so, subject to
00015  * the following conditions:
00016  *
00017  * The above copyright notice and this permission notice shall be
00018  * included in all copies or substantial portions of the Software.
00019  *
00020  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
00021  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00022  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00023  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
00024  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
00025  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
00026  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00027  */
00028 
00029 /**
00030  * @file AbstractClient.h
00031  * An abstraction layer for the SmartREST http client.
00032  */
00033 
00034 #ifndef ABSTRACTCLIENT_H
00035 #define ABSTRACTCLIENT_H
00036 
00037 #ifdef HAVE_CONFIG_H
00038 #include <config.h>
00039 #endif
00040 
00041 #include "DataGenerator.h"
00042 #include "AbstractDataSource.h"
00043 #include "AbstractDataSink.h"
00044 
00045 /** Return value indicating that the operation has been successful. */
00046 #define CLIENT_OK 0
00047 /** Return value indicating that there has been a connection error. */
00048 #define CLIENT_CONNECTION_ERROR 1
00049 /** Return value indicating that an internal error occurred. */
00050 #define CLIENT_INTERNAL_ERROR 2
00051 
00052 /*
00053  * An abstraction layer for the SmartREST http client.
00054  * 
00055  * All methods have to be called in the following order:
00056  * - beginRequest()
00057  * - sendIdentifier() (optional)
00058  * - sendData() (optional)
00059  * - endRequest()
00060  * - awaitResponse()
00061  * - receiveData() (optional)
00062  * - stop()
00063  * 
00064  * Additionally, stop() can be called at any time to reset the state of
00065  * this instance.
00066  */
00067 class AbstractClient
00068 {
00069 public:
00070     virtual ~AbstractClient() { };
00071 
00072     /**
00073      * Begins a new request. This method has to be the first call for
00074      * any request. A connection to the server will be established
00075      * and the start of a HTTP post request will be sent over the
00076      * connection including Host and Authorization headers.
00077      */
00078     virtual uint8_t beginRequest() = 0;
00079 
00080     /**
00081      * Sends the X-Id device identifier header.
00082      * @param identifier the identifier to be sent. The value has to remain
00083      *                   valid for the entire request.
00084      */
00085     virtual uint8_t sendIdentifier(const char*) = 0;
00086 
00087     /**
00088      * Sends POST data over the connection. Before the data is sent,
00089      * a Content-Length header is also sent over the connection. if the
00090      * estimated length does not match the actual conten length,
00091      * unexpected behavior will occur.
00092      * @param generator the data generator for the data to be sent
00093      */
00094     virtual uint8_t sendData(DataGenerator& generator) = 0;
00095 
00096     /**
00097      * Finishes the request. In case no data has been sent over the
00098      * connection, this method will send twice carriage-return new-line.
00099      */
00100     virtual uint8_t endRequest() = 0;
00101 
00102     /**
00103      * Blocks until the start of a response has been received.
00104      */
00105     virtual uint8_t awaitResponse() = 0;
00106 
00107     /**
00108      * Returns a data source for reading data.
00109      * When no data can be read for whatever reason,
00110      * a data source with an error state may be returned.
00111      * @return the data source to read from
00112      */
00113     virtual AbstractDataSource& receiveData() = 0;
00114 
00115     /**
00116      * Resets the connection. This method can be called at any time
00117      * and resets the state of this instance.
00118      */
00119     virtual void stop() = 0;
00120 };
00121 
00122 #endif