Initial checkin.

diff --git a/examples/AddPerson.java b/examples/AddPerson.java
new file mode 100644
index 0000000..4917684
--- /dev/null
+++ b/examples/AddPerson.java
@@ -0,0 +1,89 @@
+// See README.txt for information and build instructions.
+
+import com.example.tutorial.AddressBookProtos.AddressBook;
+import com.example.tutorial.AddressBookProtos.Person;
+import java.io.BufferedReader;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.InputStreamReader;
+import java.io.IOException;
+import java.io.PrintStream;
+
+class AddPerson {
+  // This function fills in a Person message based on user input.
+  static Person PromptForAddress(BufferedReader stdin,
+                                 PrintStream stdout) throws IOException {
+    Person.Builder person = Person.newBuilder();
+
+    stdout.print("Enter person ID: ");
+    person.setId(Integer.valueOf(stdin.readLine()));
+
+    stdout.print("Enter name: ");
+    person.setName(stdin.readLine());
+
+    stdout.print("Enter email address (blank for none): ");
+    String email = stdin.readLine();
+    if (email.length() > 0) {
+      person.setEmail(email);
+    }
+
+    while (true) {
+      stdout.print("Enter a phone number (or leave blank to finish): ");
+      String number = stdin.readLine();
+      if (number.length() == 0) {
+        break;
+      }
+
+      Person.PhoneNumber.Builder phoneNumber =
+        Person.PhoneNumber.newBuilder().setNumber(number);
+
+      stdout.print("Is this a mobile, home, or work phone? ");
+      String type = stdin.readLine();
+      if (type.equals("mobile")) {
+        phoneNumber.setType(Person.PhoneType.MOBILE);
+      } else if (type.equals("home")) {
+        phoneNumber.setType(Person.PhoneType.HOME);
+      } else if (type.equals("work")) {
+        phoneNumber.setType(Person.PhoneType.WORK);
+      } else {
+        stdout.println("Unknown phone type.  Using default.");
+      }
+
+      person.addPhone(phoneNumber);
+    }
+
+    return person.build();
+  }
+
+  // Main function:  Reads the entire address book from a file,
+  //   adds one person based on user input, then writes it back out to the same
+  //   file.
+  public static void main(String[] args) throws Exception {
+    if (args.length != 1) {
+      System.err.println("Usage:  AddPerson ADDRESS_BOOK_FILE");
+      System.exit(-1);
+    }
+
+    AddressBook.Builder addressBook = AddressBook.newBuilder();
+
+    // Read the existing address book.
+    try {
+      FileInputStream input = new FileInputStream(args[0]);
+      addressBook.mergeFrom(input);
+      input.close();
+    } catch (FileNotFoundException e) {
+      System.out.println(args[0] + ": File not found.  Creating a new file.");
+    }
+
+    // Add an address.
+    addressBook.addPerson(
+      PromptForAddress(new BufferedReader(new InputStreamReader(System.in)),
+                       System.out));
+
+    // Write the new address book back to disk.
+    FileOutputStream output = new FileOutputStream(args[0]);
+    addressBook.build().writeTo(output);
+    output.close();
+  }
+}
diff --git a/examples/ListPeople.java b/examples/ListPeople.java
new file mode 100644
index 0000000..b2f153a
--- /dev/null
+++ b/examples/ListPeople.java
@@ -0,0 +1,50 @@
+// See README.txt for information and build instructions.
+
+import com.example.tutorial.AddressBookProtos.AddressBook;
+import com.example.tutorial.AddressBookProtos.Person;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.PrintStream;
+
+class ListPeople {
+  // Iterates though all people in the AddressBook and prints info about them.
+  static void Print(AddressBook addressBook) {
+    for (Person person: addressBook.getPersonList()) {
+      System.out.println("Person ID: " + person.getId());
+      System.out.println("  Name: " + person.getName());
+      if (person.hasEmail()) {
+        System.out.println("  E-mail address: " + person.getEmail());
+      }
+
+      for (Person.PhoneNumber phoneNumber : person.getPhoneList()) {
+        switch (phoneNumber.getType()) {
+          case MOBILE:
+            System.out.print("  Mobile phone #: ");
+            break;
+          case HOME:
+            System.out.print("  Home phone #: ");
+            break;
+          case WORK:
+            System.out.print("  Work phone #: ");
+            break;
+        }
+        System.out.println(phoneNumber.getNumber());
+      }
+    }
+  }
+
+  // Main function:  Reads the entire address book from a file and prints all
+  //   the information inside.
+  public static void main(String[] args) throws Exception {
+    if (args.length != 1) {
+      System.err.println("Usage:  ListPeople ADDRESS_BOOK_FILE");
+      System.exit(-1);
+    }
+
+    // Read the existing address book.
+    AddressBook addressBook =
+      AddressBook.parseFrom(new FileInputStream(args[0]));
+
+    Print(addressBook);
+  }
+}
diff --git a/examples/Makefile b/examples/Makefile
new file mode 100644
index 0000000..999ee94
--- /dev/null
+++ b/examples/Makefile
@@ -0,0 +1,56 @@
+# See README.txt.
+
+.PHONY: all cpp java python clean
+
+all: cpp java python
+
+cpp:    add_person_cpp    list_people_cpp
+java:   add_person_java   list_people_java
+python: add_person_python list_people_python
+
+clean:
+	rm -f add_person_cpp list_people_cpp add_person_java list_people_java add_person_python list_people_python
+	rm -f javac_middleman AddPerson*.class ListPeople*.class com/example/tutorial/*.class
+	rm -f protoc_middleman addressbook.pb.cc addressbook.pb.h addressbook_pb2.py com/example/tutorial/AddressBookProtos.java
+	rm -f *.pyc
+	rmdir com/example/tutorial 2>/dev/null || true
+	rmdir com/example 2>/dev/null || true
+	rmdir com 2>/dev/null || true
+
+protoc_middleman: addressbook.proto
+	protoc --cpp_out=. --java_out=. --python_out=. addressbook.proto
+	@touch protoc_middleman
+
+add_person_cpp: add_person.cc protoc_middleman
+	c++ add_person.cc addressbook.pb.cc -lprotobuf -o add_person_cpp
+
+list_people_cpp: list_people.cc protoc_middleman
+	c++ list_people.cc addressbook.pb.cc -lprotobuf -o list_people_cpp
+
+javac_middleman: AddPerson.java ListPeople.java protoc_middleman
+	javac AddPerson.java ListPeople.java com/example/tutorial/AddressBookProtos.java
+	@touch javac_middleman
+
+add_person_java: javac_middleman
+	@echo "Writing shortcut script add_person_java..."
+	@echo '#! /bin/sh' > add_person_java
+	@echo 'java -classpath .:$$CLASSPATH AddPerson "$$@"' >> add_person_java
+	@chmod +x add_person_java
+
+list_people_java: javac_middleman
+	@echo "Writing shortcut script list_people_java..."
+	@echo '#! /bin/sh' > list_people_java
+	@echo 'java -classpath .:$$CLASSPATH ListPeople "$$@"' >> list_people_java
+	@chmod +x list_people_java
+
+add_person_python: add_person.py protoc_middleman
+	@echo "Writing shortcut script add_person_python..."
+	@echo '#! /bin/sh' > add_person_python
+	@echo './add_person.py "$$@"' >> add_person_python
+	@chmod +x add_person_python
+
+list_people_python: list_people.py protoc_middleman
+	@echo "Writing shortcut script list_people_python..."
+	@echo '#! /bin/sh' > list_people_python
+	@echo './list_people.py "$$@"' >> list_people_python
+	@chmod +x list_people_python
diff --git a/examples/README.txt b/examples/README.txt
new file mode 100644
index 0000000..b0d1a0c
--- /dev/null
+++ b/examples/README.txt
@@ -0,0 +1,25 @@
+This directory contains example code that uses Protocol Buffers to manage an
+address book.  Two programs are provided, each with three different
+implementations, one written in each of C++, Java, and Python.  The add_person
+example adds a new person to an address book, prompting the user to input
+the person's information.  The list_people example lists people already in the
+address book.  The examples use the exact same format in all three languages,
+so you can, for example, use add_person_java to create an address book and then
+use list_people_python to read it.
+
+You must install the protobuf package before you can build these.
+
+To build all the examples (on a unix-like system), simply run "make".  This
+creates the following executable files in the current directory:
+  add_person_cpp     list_people_cpp
+  add_person_java    list_people_java
+  add_person_python  list_people_python
+
+If you only want to compile examples in one language, use "make cpp",
+"make java", or "make python".
+
+All of these programs simply take an address book file as their parameter.
+The add_person programs will create the file if it doesn't already exist.
+
+These examples are part of the Protocol Buffers tutorial, located at:
+  http://code.google.com/apis/protocolbuffers/docs/tutorials.html
diff --git a/examples/add_person.cc b/examples/add_person.cc
new file mode 100644
index 0000000..2aca216
--- /dev/null
+++ b/examples/add_person.cc
@@ -0,0 +1,92 @@
+// See README.txt for information and build instructions.
+
+#include <iostream>
+#include <fstream>
+#include <string>
+#include "addressbook.pb.h"
+using namespace std;
+
+// This function fills in a Person message based on user input.
+void PromptForAddress(tutorial::Person* person) {
+  cout << "Enter person ID number: ";
+  int id;
+  cin >> id;
+  person->set_id(id);
+  cin.ignore(256, '\n');
+
+  cout << "Enter name: ";
+  getline(cin, *person->mutable_name());
+
+  cout << "Enter email address (blank for none): ";
+  string email;
+  getline(cin, email);
+  if (!email.empty()) {
+    person->set_email(email);
+  }
+
+  while (true) {
+    cout << "Enter a phone number (or leave blank to finish): ";
+    string number;
+    getline(cin, number);
+    if (number.empty()) {
+      break;
+    }
+
+    tutorial::Person::PhoneNumber* phone_number = person->add_phone();
+    phone_number->set_number(number);
+
+    cout << "Is this a mobile, home, or work phone? ";
+    string type;
+    getline(cin, type);
+    if (type == "mobile") {
+      phone_number->set_type(tutorial::Person::MOBILE);
+    } else if (type == "home") {
+      phone_number->set_type(tutorial::Person::HOME);
+    } else if (type == "work") {
+      phone_number->set_type(tutorial::Person::WORK);
+    } else {
+      cout << "Unknown phone type.  Using default." << endl;
+    }
+  }
+}
+
+// Main function:  Reads the entire address book from a file,
+//   adds one person based on user input, then writes it back out to the same
+//   file.
+int main(int argc, char* argv[]) {
+  // Verify that the version of the library that we linked against is
+  // compatible with the version of the headers we compiled against.
+  GOOGLE_PROTOBUF_VERIFY_VERSION;
+
+  if (argc != 2) {
+    cerr << "Usage:  " << argv[0] << " ADDRESS_BOOK_FILE" << endl;
+    return -1;
+  }
+
+  tutorial::AddressBook address_book;
+
+  {
+    // Read the existing address book.
+    fstream input(argv[1], ios::in | ios::binary);
+    if (!input) {
+      cout << argv[1] << ": File not found.  Creating a new file." << endl;
+    } else if (!address_book.ParseFromIstream(&input)) {
+      cerr << "Failed to parse address book." << endl;
+      return -1;
+    }
+  }
+
+  // Add an address.
+  PromptForAddress(address_book.add_person());
+
+  {
+    // Write the new address book back to disk.
+    fstream output(argv[1], ios::out | ios::trunc | ios::binary);
+    if (!address_book.SerializeToOstream(&output)) {
+      cerr << "Failed to write address book." << endl;
+      return -1;
+    }
+  }
+
+  return 0;
+}
diff --git a/examples/add_person.py b/examples/add_person.py
new file mode 100755
index 0000000..78e5696
--- /dev/null
+++ b/examples/add_person.py
@@ -0,0 +1,58 @@
+#! /usr/bin/python
+
+# See README.txt for information and build instructions.
+
+import addressbook_pb2
+import sys
+
+# This function fills in a Person message based on user input.
+def PromptForAddress(person):
+  person.id = int(raw_input("Enter person ID number: "))
+  person.name = raw_input("Enter name: ")
+
+  email = raw_input("Enter email address (blank for none): ")
+  if email != "":
+    person.email = email
+
+  while True:
+    number = raw_input("Enter a phone number (or leave blank to finish): ")
+    if number == "":
+      break
+
+    phone_number = person.phone.add()
+    phone_number.number = number
+
+    type = raw_input("Is this a mobile, home, or work phone? ")
+    if type == "mobile":
+      phone_number.type = addressbook_pb2.Person.MOBILE
+    elif type == "home":
+      phone_number.type = addressbook_pb2.Person.HOME
+    elif type == "work":
+      phone_number.type = addressbook_pb2.Person.WORK
+    else:
+      print "Unknown phone type; leaving as default value."
+
+# Main procedure:  Reads the entire address book from a file,
+#   adds one person based on user input, then writes it back out to the same
+#   file.
+if len(sys.argv) != 2:
+  print "Usage:", sys.argv[0], "ADDRESS_BOOK_FILE"
+  sys.exit(-1)
+
+address_book = addressbook_pb2.AddressBook()
+
+# Read the existing address book.
+try:
+  f = open(sys.argv[1], "rb")
+  address_book.ParseFromString(f.read())
+  f.close()
+except IOError:
+  print sys.argv[1] + ": File not found.  Creating a new file."
+
+# Add an address.
+PromptForAddress(address_book.person.add())
+
+# Write the new address book back to disk.
+f = open(sys.argv[1], "wb")
+f.write(address_book.SerializeToString())
+f.close()
diff --git a/examples/addressbook.proto b/examples/addressbook.proto
new file mode 100644
index 0000000..b14829e
--- /dev/null
+++ b/examples/addressbook.proto
@@ -0,0 +1,30 @@
+// See README.txt for information and build instructions.
+
+package tutorial;
+
+option java_package = "com.example.tutorial";
+option java_outer_classname = "AddressBookProtos";
+
+message Person {
+  required string name = 1;
+  required int32 id = 2;        // Unique ID number for this person.
+  optional string email = 3;
+
+  enum PhoneType {
+    MOBILE = 0;
+    HOME = 1;
+    WORK = 2;
+  }
+
+  message PhoneNumber {
+    required string number = 1;
+    optional PhoneType type = 2 [default = HOME];
+  }
+
+  repeated PhoneNumber phone = 4;
+}
+
+// Our address book file is just one of these.
+message AddressBook {
+  repeated Person person = 1;
+}
diff --git a/examples/list_people.cc b/examples/list_people.cc
new file mode 100644
index 0000000..bd9a583
--- /dev/null
+++ b/examples/list_people.cc
@@ -0,0 +1,65 @@
+// See README.txt for information and build instructions.
+
+#include <iostream>
+#include <fstream>
+#include <string>
+#include "addressbook.pb.h"
+using namespace std;
+
+// Iterates though all people in the AddressBook and prints info about them.
+void ListPeople(const tutorial::AddressBook& address_book) {
+  for (int i = 0; i < address_book.person_size(); i++) {
+    const tutorial::Person& person = address_book.person(i);
+
+    cout << "Person ID: " << person.id() << endl;
+    cout << "  Name: " << person.name() << endl;
+    if (person.has_email()) {
+      cout << "  E-mail address: " << person.email() << endl;
+    }
+
+    for (int j = 0; j < person.phone_size(); j++) {
+      const tutorial::Person::PhoneNumber& phone_number = person.phone(j);
+
+      switch (phone_number.type()) {
+        case tutorial::Person::MOBILE:
+          cout << "  Mobile phone #: ";
+          break;
+        case tutorial::Person::HOME:
+          cout << "  Home phone #: ";
+          break;
+        case tutorial::Person::WORK:
+          cout << "  Work phone #: ";
+          break;
+      }
+      cout << phone_number.number() << endl;
+    }
+  }
+}
+
+// Main function:  Reads the entire address book from a file and prints all
+//   the information inside.
+int main(int argc, char* argv[]) {
+  // Verify that the version of the library that we linked against is
+  // compatible with the version of the headers we compiled against.
+  GOOGLE_PROTOBUF_VERIFY_VERSION;
+
+  if (argc != 2) {
+    cerr << "Usage:  " << argv[0] << " ADDRESS_BOOK_FILE" << endl;
+    return -1;
+  }
+
+  tutorial::AddressBook address_book;
+
+  {
+    // Read the existing address book.
+    fstream input(argv[1], ios::in | ios::binary);
+    if (!address_book.ParseFromIstream(&input)) {
+      cerr << "Failed to parse address book." << endl;
+      return -1;
+    }
+  }
+
+  ListPeople(address_book);
+
+  return 0;
+}
diff --git a/examples/list_people.py b/examples/list_people.py
new file mode 100755
index 0000000..76f4bf1
--- /dev/null
+++ b/examples/list_people.py
@@ -0,0 +1,38 @@
+#! /usr/bin/python
+
+# See README.txt for information and build instructions.
+
+import addressbook_pb2
+import sys
+
+# Iterates though all people in the AddressBook and prints info about them.
+def ListPeople(address_book):
+  for person in address_book.person:
+    print "Person ID:", person.id
+    print "  Name:", person.name
+    if person.HasField('email'):
+      print "  E-mail address:", person.email
+
+    for phone_number in person.phone:
+      if phone_number.type == addressbook_pb2.Person.MOBILE:
+        print "  Mobile phone #: ",
+      elif phone_number.type == addressbook_pb2.Person.HOME:
+        print "  Home phone #: ",
+      elif phone_number.type == addressbook_pb2.Person.WORK:
+        print "  Work phone #: ",
+      print phone_number.number
+
+# Main procedure:  Reads the entire address book from a file and prints all
+#   the information inside.
+if len(sys.argv) != 2:
+  print "Usage:", sys.argv[0], "ADDRESS_BOOK_FILE"
+  sys.exit(-1)
+
+address_book = addressbook_pb2.AddressBook()
+
+# Read the existing address book.
+f = open(sys.argv[1], "rb")
+address_book.ParseFromString(f.read())
+f.close()
+
+ListPeople(address_book)