SUMMARY OF INTER-PROCESS COMMUNICATION Chenguang Kong

Outline  Introduction  Message Passing Communication  Request/Reply Communication  Transaction Communication  Name and Directory Services  Investigation on Future Work

Introduction  A set of methods for the exchange of data among multiple processes or computers  Divided into different methods based on the bandwidth and latency of communication between the processes, and the type of data being communicated  Message Passing Communication  Request/Reply Communication  Transaction Communication

Message Passing  A specification allowing computers communicate with each other  Lowest level of inter-process communicate  Two message passing primitives  Send(destination,message)  Receive(source,message)  Two types: pipe and socket`

Message Passing  Pipe  Unidirectional communication  Implemented with finite size, FIFO byte stream buffer maintained by the kernel  One process writes data into tail end of pipe while another process reads from head end of the pipe.

Message Passing  Socket  A communication end point of a communication link managed by the transport services  The most popular message passing API  The goal of secure socket layer: Privacy by using symmetric cryptographic data encryption Integrity by using message integrity check Authenticity by using asymmetric public key cryptography

Request/Reply Communication  Technique for one application to request the services of another  The layer upper message passing  Remote Procedure Calls  Most widely used model  Communication transparency  A central component in most distributed system

Request/Reply Communication  Operations involving remote procedure call  Parameter Passing and Data Conversion What types of data can be passed How is it represented  Binding How does a client locate server and a server register  Compilation Where do the stub procedures come from How are they linked

Request/Reply Communication  Operations involving remote procedure call  Exception and Failure Handling How are errors reported and dealt  Security

Transaction Communication  The basic unit of client-server process interaction in a database system  Every transaction is ACID compliant in accordance with concurrency control and transparency in the DS

Transaction Communication  ACID  Atomicity ALL or NO operations in a transaction are performed  Consistency Consistent state is maintained before a transaction starts and after it concludes  Isolation Concurrent transactions DO NOT interfere with each other  Durability transactions results are locked/ permanent after being committed

Transaction Communication  Two Phase Commit Protocol  A type of atomic commitment protocol (ACP)  A distributed algorithm that coordinates all the processes that participate in a distributed atomic transaction on whether to commit or abort the transaction  Assures that ACID properties are achieved

Transaction Communication  Two Phase Commit Protocol

Transaction Communication  X / O PEN XA  Standard specification for distributed transaction processing (DTP) by The Open Group  describes the interface between the global transaction manager and the local resource manager  Two Phase Commit is used

Name and Directory Service  Inter-process communication in distributed systems relies on the support of a name service  A generic way of describing how a named object can be addressed and subsequently located by using its address  Enable user to reference network resources with short names instead of real addresses

Name and Directory Service  Naming structure Service/Object Attributes Name structuresAttribute partitioning Flat structure Hierarchical structure name- based resolution (white pages) Structure-free attribute- based resolution (yellow pages) Physical Organizational Functional

Name and Directory Service  Directory Service  The namespace for the network  Used to hold one or more objects as named entries  The directory design process normally has a set of rules that determine how network resources are named and identified

Name and Directory Service  Implementations of directory service  X.500 a series of computer networking standards covering electronic directory services developed by ITU-T and ISO DAP (Directory Access Protocol) DSP (Directory System Protocol) DISP (Directory Information Shadowing Protocol) DOP (Directory Operational Bindings Management Protocol)

Name and Directory Service  Implementations of directory service  Domain Name System: (DNS)  Windows NT Directory Services (NTDS)  Sun Java System Directory Server  Apache Directory Server  OpenDS  …

Potential future work  Virtualization in Cloud Computing  Every custom is arranged a virtual machine to serve them  Inter-process communication among the virtual machines is a non-trivial problem E.g. name service, network routing, directory service

Potential future work  Mixed network  Cellular network  Sensor network  Cyber physical network  Next generation network structure  Current TCP/IP structure has many open challenges  Some researchers propose to construct next generation network structure  Many topics involving inter-process communication

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