Help rqd with OrbixWeb and OrbCurrent please

3 Message(s) by 2 Author(s) originally posted in java corba

From: apm35

Date: Monday, August 20, 2007

I am working on a JAVA rewrite of a C++

<language> One of the most used {object-oriented} languages, a
	superset of {C} developed primarily by {Bjarne Stroustrup}
	<bs@alice.att.com> at {AT&T} {Bell Laboratories} in 1986.

	In C++ a {class} is a user-defined {type}, syntactically a
	{struct} with {member functions}.  {Constructors} and
	{destructors} are member functions called to create or destroy
	{instances}.  A {friend} is a nonmember function that is
	allowed to access the private portion of a class.  C++ allows
	{implicit type conversion}, {function inlining}, {overloading}
	of operators and function names, and {default function
	arguments}.  It has {streams} for I/O and {references}.

	C++ 2.0 (May 1989) introduced {multiple inheritance},
	{type-safe linkage}, pointers to members, and {abstract
	classes}.

	C++ 2.1 was introduced in ["Annotated C++ Reference Manual",
	B. Stroustrup et al, A-W 1990].

	{MS-DOS
	(ftp://grape.ecs.clarkson.edu/pub/msdos/djgpp/djgpp.zip)},
	{Unix ANSI C++
	(ftp://gnu.org/pub/gnu/g++-1.39.0.tar.Z)} - X3J16
	committee. (They're workin' on it).

	See also {cfront}, {LEDA}, {uC++}.

	{Usenet} newsgroup: {news:comp.lang.c++}.

	["The C++ Programming Language", Bjarne Stroustrup, A-W,
	1986].

	(1996-06-06)

CORBA

<standard, programming> (CORBA) An {Object Management Group}
	specification which provides a standard messaging interface
	between distributed {objects}.

	The original CORBA specification (1.1) has been revised
	through version 2 (CORBA 2) with the latest specification
	being version 3 (CORBA 3).  In its most basic form CORBA
	consists of the {Interface Definition Language} (IDL) and the
	Dynamic Invocation Interface (DII).

	The IDL definition is complied into a Stub (client) and
	Skeleton (server) component that communicate through an
	{Object Request Broker} (ORB).  When an ORB determines that a
	request is to a remote object, it may execute the request by
	communicating with the remote ORB.

	The Corba IDL can be mapped to a number of languages including
	{C}, {C++}, {Java}, {COBOL}, {Smalltalk}, {Ada}, {Lisp},
	{Python}, and {IDLscript}.  CORBA ORBs are widely available
	for a number of platforms.  The OMG standard for inter-ORB
	communication is {IIOP}, this ensures that all CORBA 2
	compliant ORBS are able to interoperate.

	See also {COSS}, {Component Object Model}, {RMI}.

	{OMG CORBA site (http://www.corba.org/)}.

	(2003-11-21)

server

1. A program which provides some service to other ({client})
	programs.  The connection between client and server is
	normally by means of {message passing}, often over a
	{network}, and uses some {protocol} to encode the client's
	requests and the server's responses.  The server may run
	continuously (as a {daemon}), waiting for requests to arrive
	or it may be invoked by some higher level daemon which
	controls a number of specific servers ({inetd} on {Unix}).

	There are many servers associated with the {Internet}, such as
	those for {HTTP}, {Network File System}, {Network Information
	Service} (NIS), {Domain Name System} (DNS), {FTP}, {news},
	{finger}, {Network Time Protocol}.  On Unix, a long list can
	be found in /etc/services or in the {NIS} database "services".
	See {client-server}.

	2. A computer which provides some service for other computers
	connected to it via a network.  The most common example is a
	{file server} which has a local disk and services requests
	from remote clients to read and write files on that disk,
	often using {Sun}'s {Network File System} (NFS) {protocol} or
	{Novell Netware} on {PCs}.  Another common example is a {web
	server}.

	[{Jargon File}]

	(2003-12-29)

using Orbix. I am
using OrbixWeb. Clients have the ability to register

1. One of a small number of high-speed memory locations in a
	computer's {CPU}.  Registers differ from ordinary
	{random access memory} in several respects:

	There are only a small number of registers (the "register
	set"), typically 32 in a modern processor though some,
	e.g. {SPARC}, have as many as 144.  A register may be directly
	addressed with a few bits.  In contrast, there are usually
	millions of words of main memory (RAM), requiring at least
	twenty bits to specify a memory location.  Main memory
	locations are often specified indirectly, using an {indirect
	addressing} mode where the actual memory address is held in a
	register.

	Registers are fast; typically, two registers can be read and a
	third written -- all in a single cycle.  Memory is slower; a
	single access can require several cycles.

	The limited size and high speed of the register set makes it
	one of the critical resources in most computer architectures.
	{Register allocation}, typically one phase of the {back-end},
	controls the use of registers by a compiled program.

	See also {accumulator}, {FUBAR}, {orthogonal}, {register
	dancing}, {register allocation}, {register spilling}.

	2. An addressable location in a {memory-mapped} peripheral
	device.  E.g. the transmit data register in a {UART}.

and deregister
themselves but not using the kind of IDL

<language>

	1. {Interactive Data analysis Language} ({Xerox}).

	2. {Interface Description Language} (Snodgrass, UNC, Arizona).

	3. {Interface Definition Language} ({SunSoft}, {OMG}).

	4. {Interactive Data Language} ({Research Systems}).

	(2004-05-07)

interface

<jargon> A boundary across which two systems communicate.  An
	interface might be a hardware connector used to link to other
	devices, or it might be a convention used to allow
	communication between two software systems.  Often there is
	some intermediate component between the two systems which
	connects their interfaces together.  For example, two {EIA-232}
	interfaces connected via a serial cable.

	See also {graphical user interface}, {Application Program
	Interface}.

	(1996-05-22)

you'd expect.
The IDL is legacy and cannot be changed. Instead of the register
method returning a token

1. <grammar> A basic, grammatically indivisible unit of a
	language such as a {keyword}, operator or identifier.
	Compare: {lexeme}.

	2. <convention> (Or "{pumpkin}") An abstact concept passed
	between cooperating agents to ensure synchronised access to a
	shared resource.  Such a token is never duplicated or
	destroyed (unless the resource is) and whoever has the token
	has exclusive access to the resource it controls.  See for
	example {token ring}.

	If several programmers are working on a program, one
	programmer will "have the token" at any time, meaning that
	only he can change the program whereas others can only read
	it.  If someone else wants to modify it he must first obtain
	the token.

	(1999-02-23)

that is used in the deregister, a proprietary
extension of Orbix is used to identify the client

<programming> A computer system or process that requests a
	service of another computer system or process (a "{server}")
	using some kind of {protocol} and accepts the server's
	responses.  A client is part of a {client-server} software
	architecture.

	For example, a {workstation} requesting the contents of a file
	from a {file server} is a client of the file server.

	(1997-10-27)

. In the C++ version
of Orbix you can get the file

<file system> An element of data storage in a {file system}.

	The history of computing is rich in varied kinds of files and
	{file systems}, whether ornate (e.g., {Macintosh file system}
	for a well-known case) or deficient (e.g., many simple
	pre-1980s file systems don't allow {directories}).

	However, the prototypical file has these characteristics:

	* It is a single sequence of bytes (but consider {Macintosh}
	{resource forks}).

	* It has a finite length, unlike, e.g. a {Unix} {device}.

	* It is stored in a {non-volatile storage} medium (but see
	{ramdrive}).

	* It exists (nominally) in a {directory}.

	* It has a name that it can be referred to by in file
	operations, possibly in combination with its {path}.

	Additionally, a file system may associate other information
	with a file, such as {permission} bits or other {file
	attributes}; timestamps for file creation, last revision, and
	last access; revision numbers (a` la VMS), and other kinds of
	{magic}.

	Compare: {document}.

	(1997-04-08)

descriptor

<operating system> An integer, string or other small data
	value which refers to one of several objects allocated to a
	program by the {operating system}, usually the {kernel}.  A
	common example is a {Unix} {file descriptor} which is a small
	integer that identifies an I/O channel.  Another example is a
	reference to an area of memory (e.g. {shared memory}).

	Compare {capability}.

	(1998-02-06)

for the underlying connection
to the client. In OrbixWeb you cannot (please correct me if I am wrong
about this). I tried to use the socket

<networking> The {Berkeley Unix} mechansim for creating a
	virtual connection between processes.  Sockets interface
	{Unix}'s {standard I/O} with its {network} communication
	facilities.  They can be of two types, stream (bi-directional)
	or {datagram} (fixed length destination-addressed messages).
	The socket library function socket() creates a communications
	end-point or socket and returns a {file descriptor} with which
	to access that socket.  The socket has associated with it a
	socket address, consisting of a {port} number and the local
	host's network address.

	{Unix manual page}: socket(2).

	(1995-01-31)

object

<object-oriented> In {object-oriented programming}, an
	instance of the data structure and behaviour defined by the
	object's {class}.  Each object has its own values for the
	{instance variables} of its class and can respond to the
	{methods} defined by its class.

	For example, an object of the "Point" class might have
	instance variables "x" and "y" and might respond to the "plot"
	method by drawing a dot on the screen at those coordinates.

	(2004-01-26)

instead with the code

<software> Instructions for a computer in some programming
	language, often {machine language}.  The word "code" is often
	used to distinguish instructions from {data} (e.g. "The code
	is marked 'read-only'") whereas "{software}" is used in
	contrast with "{hardware}" and may consist of more than just
	code.

	(2000-04-08)

below:

OrbCurrent orbCurrent = _OrbixWeb.Current();
Object socketRef = orbCurrent.get_socket();
Socket socket = (Socket)socketRef;

I then get the IP Address and port

1. <networking> A logical channel or channel endpoint in a
	communications system.  The {Transmission Control Protocol}
	and {User Datagram Protocol} {transport layer} protocols used
	on {Ethernet} use port numbers to distinguish between
	(demultiplex) different logical channels on the same {network
	interface} on a computer.

	Each {application program} has a unique port number associated
	with it, defined in /etc/services or the {Network Information
	Service} "services" database.  Some {protocols}, e.g. {telnet}
	and {HTTP} (which is actually a special form of telnet) have
	default ports specified as above but can use other ports as
	well.

	Some port numbers are defined in {RFC 3232} (which replaces
	RFC 1700).  Ports are now divided into: "Well Known" or
	"Privileged", and "Ephemeral" or "Unprivileged" (comprising
	"Registered", "Dynamic", "Private").

	(2004-12-30)

	2. <operating system, programming> To translate or modify
	{software} to run on a different {platform}, or the results of
	doing so.  The {portability} of the software determines how
	easy it is to port.

	3. <language> An {imperative} language descended from {Zed}
	from {Waterloo Microsystems} (now {Hayes} Canada) ca. 1979.

	["Port Language" document in the Waterloo Port Development
	System].

	(2002-06-19)

number from the socket and use
these as a form of client id. The trouble is, this doesn't always
work. Sometimes during testing

<testing> The process of exercising a product to identify
	differences between expected and actual behaviour.  Typically
	testing is bottom-up: {unit testing} and {integration testing}
	by developers, {system testing} by testers, and {user
	acceptance testing} by users.

	{Test coverage} attempts to assess how complete a test has
	been.

	2. The second stage in a {generate and test} search
	{algorithm}.

	[{Jargon File}]

	(2003-09-24)

when I have two clients I seem to get
getting the Socket object for the wrong client. It is as if
OrbixWeb.Current() sometimes returns the wrong value. Can anybody help
please?

Regards,

Andrew Marlow

From: Mark Woyna

Date: Monday, August 20, 2007

wrote in message:

I am working on a JAVA rewrite of a C++ CORBA server using Orbix. I am
using OrbixWeb. Clients have the ability to register and deregister
themselves but not using the kind of IDL interface you'd expect.
The IDL is legacy and cannot be changed. Instead of the register
method returning a token that is used in the deregister, a proprietary
extension of Orbix is used to identify the client. In the C++ version
of Orbix you can get the file descriptor for the underlying connection
to the client. In OrbixWeb you cannot (please correct me if I am wrong
about this). I tried to use the socket object instead with the code
below:
OrbCurrent orbCurrent = _OrbixWeb.Current();
Object socketRef = orbCurrent.get_socket();
Socket socket = (Socket)socketRef;
I then get the IP Address and port number from the socket and use
these as a form of client id. The trouble is, this doesn't always
work. Sometimes during testing when I have two clients I seem to get
getting the Socket object for the wrong client. It is as if
OrbixWeb.Current() sometimes returns the wrong value. Can anybody help
please?
Regards,
Andrew Marlow

Since you're rewriting the application

1. {application program}.

	2. {function application}.

in JAVA, do you've to stick
with OrbixWeb? You'd probably get a lot more help/support if you used
JacORB, which has a much larger active community than OrbixWeb.

Can you post the IDL?

Mark

From: apm35

Date: Tuesday, August 21, 2007

wrote in message:
wrote in message:

I found out what was wrong. The code below:

> OrbCurrent orbCurrent = _OrbixWeb.Current();
> Object socketRef = orbCurrent.get_socket();
> Socket socket = (Socket)socketRef;

only works if you say:

JAVA.util.Properties props = new JAVA.util.Properties();
props.setProperty("OrbixWeb.IT_MULTI_THREADED_SERVER",
"true");

ORB

<programming> (ORB) Part of the {OMG} {CORBA} specification,
	an ORB's basic function is to pass {method} invocation
	requests to the correct {objects} and return the results to
	the caller.

	To achieve this the ORB must be able must be able to identify
	and locate objects, handle connections from invoker and the
	data returned from methods.  Communication between the ORB and
	applications are achieved through {IDL} stubs and skeletons
	whilst the OMG has specified {IIOP} as the protocol through
	which ORBs may communicate with each other.  Using IIOP, an
	ORB may request method invocations from a remote object.

	(2003-11-21)

orb = _OrbixWeb.ORB(ORB.init(args, props));

when you initialise

<programming> To give a {variable} its first value.  This may
	be done automatically by some languages or it may require
	explicit code by the programmer.  Some languages allow
	initialisation to be combined with variable definition,
	e.g. in {C}:

		int i = 0;

	Failing to initialise a variable before using it is a common
	programming error, but one which compilers and automatic
	checkers like {lint} can easily detect.

	(1997-06-08)

the ORB.

> I then get the IP Address and port number from the socket and use
> these as a form of client id. The trouble is, this doesn't always
> work. Sometimes during testing when I have two clients I seem to get
> getting the Socket object for the wrong client. It is as if
> OrbixWeb.Current() sometimes returns the wrong value.

It was returning the wrong value due to a race condition. The ORB init
code code above has to be used according to the IONA KnowledgeBase
article at https://www.iona.com/support/kb/entry!default.jspa?categoryID=3&externalID=1933.942&fromSearchPage=true

Since you're rewriting the application in JAVA, do you've to stick
with OrbixWeb?

Yes. I wish it wasn't so.

You'd probably get a lot more help/support if you used
JacORB, which has a much larger active community than OrbixWeb.

Agreed. That is why when I first started the development

The process of analysis, design, coding and testing software.

I did use
JacORB. It enabled me to get most of the development done without
having to worry about setting up a commercial installation, checking
that I had got licences, putting in a purchase order then waiting
three months etc etc.

Regards,

Andrew Marlow

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