[occi-wg] (industry noise on CC protocols) cross post from a cloud group

Thu May 14 08:55:07 CDT 2009

I thought this might be of interest --

---------- Forwarded message ----------
From: Gervas Douglas <gervas.douglas at gmail.com>
Date: Thu, May 14, 2009 at 12:13 AM
Subject: [cloudcomputing-tech] Brogden on protocols for CC services
To: cloudcomputing-tech at yahoogroups.com

<<Call it grid computing, cloud computing or software as a service,
distributed computing is on a lot of developers minds recently. There
are so many different ways in which people can use the "cloud" that
there would appear to be no possibility of a single "framework" for
cloud based services. This has not prevented a lot of developer
discussion and fear that the "cloud" will somehow become a closed
realm of proprietary protocols as opposed to an open-source utopia.
(See for example the open cloud manifesto.) It seems to me that a
discussion of the wide range of protocols and architecture in
grid/cloud/distributed computing is in order. I am going to discuss
some of them in order of increasing complexity.

Bandwidth and storage with REST
Little change in architecture is required when an enterprise uses
cloud facillities to supplement owned server bandwidth to handle
unusual demands. As I discussed in this article, making use of cloud
bandwidth simply requires redirecting requests to a cloud URL. This
follows the REST principle that when you want the current state of a
resource, the internal details of how you get it are unimportant. No
special software beyond a HTTP server is required on the cloud server
side. The high bandwidth and storage capacities combined with low cost
and simple application make this the simplest way to take advantage of
the cloud.

Remote Procedure Calls with XML-RPC and SOAP
The concept of a Remote Procedure Call has been around for years and
forms the basic technology for much network computing. The architecure
gives the programmer an interface which lets you program as if the
method will actually be executed on your computer but will actually
run elsewhere.

The technology known as XML-RPC was the pioneer for the idea of
formatting Remote Procedure Calls in XML messages. This simple yet
powerful concept for supplying variables to call a method on a remote
computer is still in use. However, some developers wanted more, so we
got SOAP. Originally SOAP stood for Simple Object Access Protocol but
it certainly is not simple and has little requirement to use objects.
The inescapable disadvantage of XML encoded messages is that they are
very inefficient in terms of actual data transmission and CPU time
required to parse the message.

On the plus side, by using text XML documents, developers can paper
over the incompatibilities between different hardware and software in
distributed systems. Furthermore everything that is transmitted is
human readable and it is easy to create or read messages with a
variety of techniques. As the evolution of SOAP shows, it is easy to
add capabilities to XML formatted messages without seriously impacting
existing applications.

Your SOAP or XML-RPC server on the cloud side will require custom
programming but it will be a familiar environment, typically JAVA with
an SQL server and huge huge disk capacity. Cloud vendors such as
Amazon are rushing such capabilities into service.

RPC between objects with CORBA
The Common Object Requesting Broker Architecture or CORBA is an early
effort at a standard to enable object interactions within a network.
It uses an interface definition language (IDL) to define the face
these objects present and an object request broker (ORB) to negotiate
the exchange of information about objects. CORBA makes a major effort
to ensure that the IDL can be supported in many languages and
operating systems. The Internet Inter-Orb Protocol (IIOP) is the
protocol by which ORBs communicate between heterogeneous mixes of
computer systems using TCP/IP. It should not surprise you that object
oriented languages like Java are easy to map to IDL. Support for IIOP
has been part of the Java standard library since 1998.

In spite of the fact that there have been many cycles of popular
"latest thing" buzz-words since CORBA was introduced, it continues to
be used in network computing with strong and mature industry support.
The Object Management Group is the non-profit industry consortium
responsible for maintaining the standard. Version 1.0 was released in
1991 and we are currently at version 3.1 released in 2004 so you can
see that this is a refined and mature standard. You can get quite an
argument among developers as to whether CORBA and/or SOAP is too
complex for the future of cloud computing and SOA.

Application specific protocols
A recent news article indicated that Microsoft's "cloud services
operating system" called Azure, will eventually allow the use of the
"Tabular Data Streams" protocol in communicating with SQL Data
Services, the cloud version of SQL. It appears that customers really
wanted to enable cloud relational database operations similar to
existing in-house applications rather than translating requests to
REST style. I think it is likely we will see a lot more cloud services
that use application specific protocols.

Resources
REST versus SOAP - the REST story
REST versus SOAP - the SOAP story
Home page for the "open cloud manifesto"
Wikipedia history of Tabular Data Streams protocol>>

You can find this at:
http://searchsoa.techtarget.com/tip/0,289483,sid26_gci1355134_mem1,00.html?track=NL-130&ad=703436&Offer=SOAunsc513pcc&asrc=EM_USC_6900715&uid=5532089

Gervas

 1
New Members

Visit Your Group
Give Back

Yahoo! for Good

Get inspired

by a good cause.

Y! Toolbar

Get it Free!

easy 1-click access

to your groups.

Yahoo! Groups

Start a group

in 3 easy steps.

Connect with others.

.
__,_._,___