In this readme you will find more information about the network service. It explains how the communication between the client and service works and how the program itself works.
The program is written in QT Creator, and the flowcharts are made on the website miro.com
in this project there are three applications: the client, benternet and the service.
Below you can read how they communicate with each other. All communication is done with TCP protocol.
The client is what you operate as a user, in the client you can give your commands. These commands will be sent to benternet. The client sends to benternet on port 24041.
When benternet gets the command from the client it will sent it to all services that are connected on it on port 24042. Only the service that is listening to shop! will accept the command.
When the service has done his job, and has a command that need to be send back to the client, it sends the command to benternet also on port 24041.
When benternet get this command, it will also send it to all services that are connected to it on port 24042. Only the service that is listening to shop?(+shopID) will accept the command.
The messages that the client send is build up with 4 parts:
-
pushSubject: The pushSubject is pre coded, and its equal to shop!.
-
shopID: The shopID is a string that will be random generated by the client application. This shopID will be used so that the service knows from what client he receive the messages.
-
command: The command is used so the service know what he has to do. The user need to type the command by itself.
- add
- get
- del
- cut
-
product: After the command the user need to type the product he wants to add or del. It's not allowed to use a space between the command and the product.
-
example:
- shop!AGHIKLBDYaddpizza
- shop!HKJDKHUIEGHFaddwater
- shop!DMLJFKLDget
- ...
The messages that the client send is build up with 3 parts. Sometimes there is also a 4 part:
- pushSubject: Als here the pushSubject is pre coded and is equal to shop?
- shopID: The shopID it the ID that the service get from the client.
- product: The product is the product the service worked with.
- additional text: In some cases there is additional text so the user knows what happend.
- example:
- shop?AGHIKLBDYaddpizza has been added to basket!
- shop?LKJDFJLUdelmilk is removed!
- ...
Like you can see, both client and service application has a push and receive function. When you start up the client, it will first push a command and then start listening to receive command. While the service will firts lissen and then push when you start it.
Also the client and service need to listen at different subjects. Otherwise they will also get their own command when benternet is sending on port 24042.
In this part the code from both application will be explained.
First the code will generate his own shopID.
int size = (rand() % 5) +5;
for(int i=0; i<size; i++)
{
shopID = shopID + char('A' + rand() % 26);
}
cout << shopID << endl;The application wil first ask to type your command and product. Afhter this it will add all strings together to one string.
When the string is created, the whole string will be send with ventilator.send(...).
cout << "Enter the command: "; //Print out the text
cin >> sendString; //Let the user type in a command
sendString = pushSubject + shopID + sendString;
ventilator.send(sendString.c_str(), sendString.size()); //Send the stringWhen the client has send his messages, it will start lissening to incoming messages. Once it has received a messages, it will rebuild this messages to a string.
Then the first five characters of the string will be removed (shop?).
The client application will keep lissening until it received the messages end. When it received the messages end, the code will go back to "send messages" part.
do{
subscriber.recv(msg); //Receive the message
receivedString = string( (char*) msg->data(), msg->size() ); //Convert the received message to a string
receivedString.erase(0, 5); //Remove the first 5 characters of the string (sub topic)
if(receivedString != "end") //If not end
{
receivedString = delUppChar(receivedString);
cout << " -> " << receivedString << endl; //Print out the text
}
}while(receivedString != "end"); //As long as the end command is not receivedThe first thing that the service will do is lissening to incoming messages. Once it has received a messages, it will rebuild this messages to a string.
Also here the first 5 characters will be removed from the string (shop!).
The next step is to separate the string in different parts. The first part is the shopID, with the function delLowChar we can remove the lowercase chars from the string.
The second part are all the lowercase chars. By using the function delUppChar we can remove all the uppercase chars from the string.
At the end we will create the firstThree sting by remving all the chars afther the first three chars, and the theProduct string by removing the first three chars.
Afhter all these steps we have 3 strings to work with:
- shopID
- firsthree
- theProduct
subscriber.recv(msg); //Receive the message
receivedString = string((char*) msg->data(), msg->size()); //Convert the received message to a string
receivedString.erase(0,5); //Remove the first 5 characters of the string (sub topic)
shopID = delLowChar(receivedString);
firstThree = delUppChar(receivedString); //Set firstThree equal to receivedString
theProduct = delUppChar(receivedString); //Set theProduct equal to receivedString
firstThree.erase(3,firstThree.size()); //Remove everything after the first 3 characters
theProduct.erase(0, 3); //Remove the first 3 charactersWhen you start the program, the shopIDvector will be empty. So the first time the programming runs, the shopID will be add to the vector.
Every other time the program will first check if the shopID is already add into the shopIDvector. If the ID is in the vector, the function readTXTfile will read out the txt file and push_back everyting in to a vector.
Else the shopID will be add to the shopIDvector.
if(shopIDvector.size()==0)
{
shopIDvector.push_back(shopID);
cout << "new customer by " << shopID << endl;
}
else
{
for(int k=0; k<shopIDvector.size(); k++)
{
if(shopID == shopIDvector.at(k))
{
shopBag = readTXTfile(shopID);
break;
}
else
{
shopIDvector.push_back(shopID);
cout << "new customer by " << shopID << endl;
}
}
}In the add function, the product will be add to the shopBag vector. The function will also send a message back to the client, and the end message.
vector <string> add(string product, vector <string> bag, string push, string id)
{
zmq::context_t context(1);
zmq::socket_t ventilator( context, ZMQ_PUSH ); //Service push
ventilator.connect( "tcp://benternet.pxl-ea-ict.be:24041" ); //Service push
string sendString = "";
cout << "add " << product << " by " << id << endl; //Print out the text
bag.push_back(product); //Add the product to the shopBag
sendString = push + id + product + " has been added to your basket!"; //Create the string that will be send back
ventilator.send(sendString.c_str(), sendString.size()); //Send the string
sendString = push + id + "end";
ventilator.send(sendString.c_str(), sendString.size()); //Forward that client may stop listening
return bag;
}With the get function the service will send each element of the shopBag vector to the client. At the end it will also send the end message.
void get(string product, vector <string> bag, string push, string id)
{
zmq::context_t context(1);
zmq::socket_t ventilator( context, ZMQ_PUSH ); //Service push
ventilator.connect( "tcp://benternet.pxl-ea-ict.be:24041" ); //Service push
string sendString = "";
cout << "get shopBag by " << id << endl; //Print out the text
for(int j=0; bag.size()>j; j++) //Do this as many times as the vector is large
{
product = bag.at(j); //Take the element from the vector and copy it into theProduct
sendString = push + id + product; //Create the string that will be send back
ventilator.send(sendString.c_str(), sendString.size()); //Send the string
}
sendString = push + id + "end";
ventilator.send(sendString.c_str(), sendString.size()); //Forward that client may stop listening
}The del function will delete the product out of the shopBag vector. Also here will the end message be send to the client.
vector <string> del(string product, vector <string> bag, string push, string id)
{
zmq::context_t context(1);
zmq::socket_t ventilator( context, ZMQ_PUSH ); //Service push
ventilator.connect( "tcp://benternet.pxl-ea-ict.be:24041" ); //Service push
string sendString = "";
int i = 0;
cout << "del " << product << " by " << id << endl; //Print out the text
while(product != bag.at(i)){i++;} //Look at which positions the element is in the vector
bag.erase(bag.begin()+i); //Remove the element at position i in the vector
sendString = push + id + product + " is removed"; //Create the string that will be send back
ventilator.send(sendString.c_str(), sendString.size()); //Send the string
sendString = push + id + "end";
ventilator.send(sendString.c_str(), sendString.size()); //Forward that client may stop listening
return bag;
}When the product are add or delete out of the shopBag vector. the function writeTXTfile will overwrite the txt file with the right shopID.
vector <string> bag;
ifstream txtFile("../txt_files/" + id + ".txt");
string prouct;
while(getline(txtFile, prouct)){bag.push_back(prouct);}
txtFile.close();
return bag;At the end the shopBag will be cleared so its ready to use again.
shopBag.clear();There are also a few Python codes to check out.