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Session Presented at 5th IndicThreads.com Conference On Java held on 10-11 December 2010 in Pune, India WEB: http://J10.IndicThreads.com ------------
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ThriftScalable Cross Language Services Implementation
Sanjoy Singh Senior Team Lead
Talentica S/W (I) Pvt Ltd
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Scalability ??
Design/Program is said to scale …
- if it is suitably efficient and practical when applied to large situations
Measures
Load Functional
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Agenda Key Components/Challenges for Cross
Language Interactions Various System for Cross Language
Interactions Dive Into Apache Thrift
Principle Of Operation Example Thrift Stack Versioning
Why to use Thrift. Limitations? Quick Code Walkthrough
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LAMP + Services
High-Level Goal: Enable transparent interaction between these.
…and some others too.
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High Level Goals !
Transparent Interaction between multiple programming languages.
Maintain Right balance between Performance Ease and speed of development Availability of existing libraries. etc
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Simple Distributed Architecture
Communication protocol, Data format
Sending requests,
getting results
Sending requests,
getting results
Waiting for requests
(known location,
known port)
Waiting for requests
(known location,
known port)
Basic questions are:Basic questions are:
What kind of protocol to use, and what What kind of protocol to use, and what data to transmitdata to transmit
What to do with requests on the server What to do with requests on the server sideside
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Key Components/Challenges !
Type system Transport system Protocol system Versioning Processor Performance
No problem can stand the assault of sustained thinking.
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Hasn’t this been done before? (yes.)
SOAP
CORBA
COM
Pillar
Protocol Buffers etc
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Should we pick up one of those? (not sure)
SOAP XML, XML, and more XML
CORBA Over designed and Heavyweight
COM Embraced mainly in Windows Client Software
Pillar Slick! But no versioning/abstraction.
Protocol Buffers etc Closed source Google deliciousness
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As a developer, what are you looking for?
Be Patient, I have something for you in the subsequent slides !!
Decision Time !
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Solution
Apache Thrift
Software framework for scalable cross-language services development.
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Apache Thrift - Introduction
Originally developed at Facebook Open sourced in April 2007 Easy exchange of data Cross language serialization with
minimal overhead . Thrift tools can generate code for
C++, Java, Python, PHP, Ruby, Erlang, Perl, Haskell, C#, Cocoa, Smalltalk and OCaml
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Lets Dive It..
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Principle Of Operation
Thrift Code Generator Tool(written in C++)
Create a thrift fileeg demo.thrift
Define Data types and Service
interfaces
Build Thrift platform files
Demo.php Demo.javaDemo.pyDemo.cpp
Create Server/Client AppRun the Server
Server implements Services and Client calls
them
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Thrift Cares About Type Definitions Service Definitions
Thrift Doesn’t Care About Wire Protocol (internal XML...) Transport (HTTP? Sockets? Whatevz!) Programming Languages
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Enough Banter. Show Us the Goodz.// Include other thrift files
include "shared.thrift“
namespace java calculator
enum Operation { // define enums
ADD = 1,
SUBTRACT = 2,
MULTIPLY = 3,
DIVIDE = 4
}
struct Work {// complex data structures
1: i32 num1 = 0,
2: i32 num2,
3: Operation op,
4: optional string comment,
}
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Enough Banter. Show Us the Goodz.
// Exception
exception InvalidOperation {
1: i32 what,
2: string why
}
// Service
service Calculator extends shared.SharedService {
void ping(),
i32 add(1:i32 num1, 2:i32 num2),
i32 calculate(1:i32 logid, 2:Work w) throws (1:InvalidOperation ouch),
oneway void zip()
}
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Enough Banter. Show Us the Goodz.// Include other thrift files
include "shared.thrift“
namespace java calculator
enum Operation { // define enums
ADD = 1,
SUBTRACT = 2,
MULTIPLY = 3,
DIVIDE = 4
}
struct Work {// complex data structures
1: i32 num1 = 0,
2: i32 num2,
3: Operation op,
4: optional string comment,
}
// Exception
exception InvalidOperation {
1: i32 what,
2: string why
}
// Service
service Calculator extends shared.SharedService {
void ping(),
i32 add(1:i32 num1, 2:i32 num2),
i32 calculate(1:i32 logid, 2:Work w) throws (1:InvalidOperation ouch),
oneway void zip()
}
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What DOES that do?
Generates definitions for all the types in each language
Generates Client and Server interfaces for each language
What DOESNT that do? Anything to do with sockets Anything to do with serialization
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Magically Generated Files
gen-java/calculatordemo
Calculator.java
InvalidOperation.java
Operation.java
Work.java
gen-php/
Calculator.php
calculator_types
gen-py/
ttypes.py
Calculator.py
Calculator-remote
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Thrift Philosophy
Create a system that is abstracted in a systematic way, such that developers can easily extend it to suit their needs and function in custom environments.
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Structs don’t have any code to do with serialization or sockets, etc.
But they know how to read and write themselves… How does that work?
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The Thrift Stack The Thrift stack is a common class hierarchy implemented in each language
that abstracts out the tricky details of protocol encoding and network communication.
It provides a simple interface for generated code to use.
There are two key interfaces:
TTransport
De-coupled the transport layer from Code Generation Layer. Provides read() and write(), with a set of other helpers like open(), close(),
etc. Implementation - TSocket, TFileTransport, TBufferedTransport,
TFramedTransport, TMemoryBuffer. TProtocol
Separate Data Structure from Transport representation. Provides the ability to read and write various types of data, i.e. readI32(),
writeString(), etc. Supports Bi-directional sequenced messaging and encoding of base types,
container and struts.
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The Thrift Stack
Objectwrite()
TTransport
TProtocol TTransport TProtocol
Objectread()
Information Flow!
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Versioning (applications change a lot, not protocols!) What happens when definitions change?
Struct needs a new member Function needs a new argument
No Problem! We’ve got Field Identifiers!
Example:
struct Work {
1: i32 num1 = 0,
2: i32 num2,
3: Operation op,
4: optional string comment,
}
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Versioning - Case AnalysisAdd a Field
New Client, Old ServerServer sees a field id that it doesn’t recognize, and safely
ignores it.
Old Client, New ServerServer doesn’t see the field id it expects. Leaves it unset in
object, server implementation can properly handle
Remove a Field New Client, Old Server
Server doesn’t see field it expects. Analogous to above. Old Client, New Server
Old client sends deprecated field. Server politely ignore it. Analogous to the top case.
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Why to use Thrift … Less time wasted by individual developers
No duplicated networking and protocol code less time dealing with boilerplate stuff Write your client and server in about 5 minutes
Less maintenance One networking code base that needs maintenance Fix bugs once, rather than repeatedly in every server
Division of labour Work on high-performance servers separate from
applications Common toolkit
Code reuse and shared tools
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Why to use Thrift … Cross-language serialization with lower overhead
than alternatives such as SOAP due to use of binary format
A lean and clean library. No framework to code to. No XML configuration files.
The language bindings feel natural. For example Java uses ArrayList<String>. C++ uses std::vector<std::string>.
The application-level wire format and the serialization-level wire format are cleanly separated. They can be modified independently.
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Why to use Thrift …
The predefined serialization styles include: binary, HTTP-friendly and compact binary.
Soft versioning of the protocol.
No build dependencies or non-standard software. No mix of incompatible software licenses.
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Limitations / Non-Features
Is struct inheritance/polymorphism supported?
No, it isn’t Can I overload service methods?
Nope. Method names must be unique. Heterogeneous containers Not supported
Is there any enough documentation on Thrift development?
I think this is one weak area.
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Steps/Code Walkthrough(Lets build the example described earlier)
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Some Real Time Example
Facebook Search Service
AdServer, Blogfeeds, CSSParser, Memcached, Network Selector, News Feed, Scribe etc
PHP based Web App
Thrift PHP Lib Search Service(implemented in C++
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Why Should I not try this?
Guess the answer?
Answer: Please do let me know at [email protected]
Skpe_id/Gtalk_id : sanjoy_17 /sanjoy17
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References
http://incubator.apache.org/thrift/http://incubator.apache.org/thrift/stat
ic/thrift-20070401.pdf
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Thanks !!!