Noob here and I'm trying to have the Arduino parse an XML file and save the results to variables that I can later pass onto an LCD screen as well as to pumps for use. My project is a "mixing machine" for virgin drinks. I've tried several different XML Parsers however I can't seem to get the results to be stored as strings or character arrays so that I can use them elsewhere in the program. I just can't seem to get the darn thing working. I can get the variables saved in the function and used there, however anytime I try and display them on the Serial in the main loop I get nothing. 
Here is the contents of my XML file:
<instructions>
<name>Kirk Holmes</name>
<flavor_name>Root Beer Float</flavor_name>
<mix_volume>15</mix_volume>
<pump_instructions>
<pump1>1</pump1>
<pump2>2</pump2>
<pump3>3</pump3>
<pump4>4</pump4>
<pump5>5</pump5>
</pump_instructions>
<date_time_submitted>
<month>6</month>
<day>20</day>
<year>2013</year>
<hour>12</hour>
<minute>01</minute>
<second>00</second>
</date_time_submitted>
</instructions>
Here is my code:
//////////////////////////////////////////////
// Get XML formatted data from the web.
// 1/6/08 Bob S. - Created
//
// Assumptions: single XML line looks like:
// <tag>data</tag> or <tag>data
//
// Get current weather observation for Raleigh from weather.gov in XML format
//
//////////////////////////////////////////////
// Include description files for other libraries used (if any)
#include <string.h>
#include <Ethernet.h>
#include <SPI.h>;
// Define Constants
// Max string length may have to be adjusted depending on data to be extracted
#define MAX_STRING_LEN 20
// Setup vars
char tagStr[MAX_STRING_LEN] = "";
char dataStr[MAX_STRING_LEN] = "";
char tmpStr[MAX_STRING_LEN] = "";
char endTag[3] = {'<', '/', '\0'};
int len;
// DECLARED VARIABLES HERE FOR GLOBAL USE
char* name;
char* flavor_name;
char* mix_volume;
// Flags to differentiate XML tags from document elements (ie. data)
boolean tagFlag = false;
boolean dataFlag = false;
// Ethernet vars
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192, 168, 1, 177 };
byte server[] = { 192, 168, 1, 110 }; // My server at home
// Start ethernet client
EthernetClient client;
void setup()
{
Serial.begin(9600);
Serial.println("Starting WebWx");
Serial.println("connecting...");
Ethernet.begin(mac, ip);
delay(1000);
if (client.connect(server, 80)) {
Serial.println("connected");
client.println("GET /instructions.xml HTTP/1.0");
client.println();
delay(2000);
} else {
Serial.println("connection failed");
}
}
void loop() {
// Read serial data in from web:
while (client.available()) {
serialEvent();
}
if (!client.connected()) {
//Serial.println();
//Serial.println("Disconnected");
client.stop();
// Time until next update
//Serial.println("Waiting");
for (int t = 1; t <= 15; t++) {
delay(60000); // 1 minute
}
if (client.connect(server, 80)) {
//Serial.println("Reconnected");
client.println("GET /instructions.xml HTTP/1.0");
client.println();
delay(2000);
} else {
Serial.println("Reconnect failed");
}
}
}
// Process each char from web
void serialEvent() {
// Read a char
char inChar = client.read();
//Serial.print(".");
if (inChar == '<') {
addChar(inChar, tmpStr);
tagFlag = true;
dataFlag = false;
} else if (inChar == '>') {
addChar(inChar, tmpStr);
if (tagFlag) {
strncpy(tagStr, tmpStr, strlen(tmpStr)+1);
}
// Clear tmp
clearStr(tmpStr);
tagFlag = false;
dataFlag = true;
} else if (inChar != 10) {
if (tagFlag) {
// Add tag char to string
addChar(inChar, tmpStr);
// Check for </XML> end tag, ignore it
if ( tagFlag && strcmp(tmpStr, endTag) == 0 ) {
clearStr(tmpStr);
tagFlag = false;
dataFlag = false;
}
}
if (dataFlag) {
// Add data char to string
addChar(inChar, dataStr);
}
}
// If a LF, process the line
if (inChar == 10 ) {
/*
Serial.print("tagStr: ");
Serial.println(tagStr);
Serial.print("dataStr: ");
Serial.println(dataStr);
*/
// Find specific tags and print data
if (matchTag("<name>")) {
Serial.println("Name: ");
name = dataStr;
Serial.print(name);
}
if (matchTag("<flavor_name>")) {
Serial.print(" Flavor Name: ");
flavor_name = dataStr;
Serial.print(flavor_name);
}
if (matchTag("<mix_volume>")) {
Serial.print(" Volume to Mix: ");
mix_volume = dataStr;
Serial.print(mix_volume);
Serial.print(" ");
}
// Clear all strings
clearStr(tmpStr);
clearStr(tagStr);
clearStr(dataStr);
// Clear Flags
tagFlag = false;
dataFlag = false;
}
}
/////////////////////
// Other Functions //
/////////////////////
// Function to clear a string
void clearStr (char* str) {
int len = strlen(str);
for (int c = 0; c < len; c++) {
str[c] = 0;
}
}
//Function to add a char to a string and check its length
void addChar (char ch, char* str) {
char *tagMsg = "<TRUNCATED_TAG>";
char *dataMsg = "-TRUNCATED_DATA-";
// Check the max size of the string to make sure it doesn't grow too
// big. If string is beyond MAX_STRING_LEN assume it is unimportant
// and replace it with a warning message.
if (strlen(str) > MAX_STRING_LEN - 2) {
if (tagFlag) {
clearStr(tagStr);
strcpy(tagStr,tagMsg);
}
if (dataFlag) {
clearStr(dataStr);
strcpy(dataStr,dataMsg);
}
// Clear the temp buffer and flags to stop current processing
clearStr(tmpStr);
tagFlag = false;
dataFlag = false;
} else {
// Add char to string
str[strlen(str)] = ch;
}
}
// Function to check the current tag for a specific string
boolean matchTag (char* searchTag) {
if ( strcmp(tagStr, searchTag) == 0 ) {
return true;
} else {
return false;
}
}
