Lab 3 - Thrift

Lab tasks

The tasks for today are:

• Use Apache Thrift in a simple example
  • install Thrift
  • download the example code
  • compile and run the example program
• Lab activity
  • modify the example program
  • connect to our server and make a remote procedure call
  • send the response by e-mail, to be counted as lab activity
• Read the homework assignment

Apache Thrift

Apache Thrift is a cross-platorfm cross-language RPC library.

• Home page: https://thrift.apache.org
  • C++ Tutorial
  • Java Tutorial
  • Python Tutorial
  • Node Tutorial
  • Node Tutorial
• Installation instructions
• Example from lectures: https://github.com/d-iii-s/teaching-middleware/tree/master/src/thrift-basic-server

Example Source

Download the source code. Unzip the code and explore the sources in the Example-XXX directories.

C++

• Example.thrift - describes an interface of a remote service using Thrift IDL. This file is used by Thrift compiler to generate code for any programming language supported by Thrift
• client.cpp - a simple program which connects to a server and calls a remote procedure.
  • Connects to localhost:5000.
  • Uses a multiplexed binary protocol. Multiplexing allows providing multiple services on a single port.
• server.cpp - a simple server providing an implementation of Example.
  • Listens on localhost:5000.
  • Uses TThreadedServer to serve clients in multiple threads.
  • Uses TProcessorFactory to create a processor and handler for each client connection. This allows the handler to keep state associated with the client.
• Makefile - runs the Thrift compiler and C++ compiler
  • Adds generated header files on the include path.
  • Compiles server.cpp and client.cpp and the generated source files.
• gen-cpp - a directory created after running the Thrift compiler.
  • Contains generated .h and .cpp files
  • Example.h - defines ExampleIf, an abstract base class for the service handler
  • Example_server.skeleton.cpp - not used in compilation, but contains skeleton code for implementation of the server

Java

• src/main/java/ExampleClient.java - a simple program which connects to a server and calls a remote procedure.
• pom.xml - Maven build file
  • runs the Thrift compiler
  • ensures Thrift libraries on the classpath
• target/generated-sources/thrift - a directory created after running the Thrift compiler from Maven.
  • Contains generated .java files

Node

• index.js - a simple program which connects to a server and calls a remote procedure.
• package.json - npm package file
  • specifies dependency on thrift
  • defines a command to run the Thrift compiler
• gen-nodejs - a directory created after running the Thrift compiler.
  • Contains generated .js files

Python

• client.py - a simple program which connects to a server and calls a remote procedure.
• generate.sh - runs the Thrift compiler
• run.sh - runs the client with the generated files on PYTHONPATH
• gen-py - a directory created after running the Thrift compiler.
  • Contains generated .py files

Running the example

C++

1. Compile the programs
   • make
2. Run the server
   • ./server
3. Run the client
   • ./client

Setting up Thrift directories

If you have installed thrift manually to your home directory (for example if using lab computers), you might have to set up directory paths, so that the compiler and the linker can find the necessary files.

• Edit the Makefile:
  • Add -I$(HOME)/thrift/include to the g++ commands (2 places)
  • Add -L$(HOME)/thrift/lib to the g++ commands (2 places)
• Before running make, set up path to thrift binary:
  • export PATH="$PATH:$HOME/thrift/bin"
• Before running the programs, set up path to thrift libraries:
  • export LD_LIBRARY_PATH="$HOME/thrift/lib"

Java

1. Compile the client
   • mvn compile
2. Run the C++ server
3. Run the client
   • mvn exec:java

Node

1. Install required packages
   • npm install
2. Generate code
   • npm run generate
3. Run the C++ server
4. Run the client node .

Python

1. Generate code
   • bash generate.sh
2. Run the C++ server
3. Run the client
   • bash run.sh

Lab activity task

With a client in any language, connect to our server at lab.d3s.mff.cuni.cz:5000, and call the method with your own unique string. The server will respond with a text containing an integer key. Send this by e-mail to the lab teacher.

Note: if you do not receive an integer key on the first try, then follow the instructions you received.

Homework task

• Read the homework assignment.
• Explore the provided application.
  • items.hpp defines library items
    • Classes Book, CD and Magazine extending a common base Item.
    • Have fields name, length and available of different types.
  • database.hpp generates a database of random items an allows performing simple queries, retrieving items in batches of chosen size.
  • summary.hpp builds a summary from given items.
  • string_conversions.hpp contains helper function for converting between vectors, sets and strings.
  • main.cpp shows how to create a database, do a simple query, and generate a summary.

Running the example

1. Compile the program
   • make
2. Run the program
   • ./main