A distributed object is an object which is resident on one computer and for which methods can be invoked associated with code resident on other computers. (Ince, 2002, p.84). A good distributed objects technology should totally hide the underlying communication details from the programmer.

CORBA, which is a multi-language technology, and RMI, which is a Java-based technology.

Distributed objects technology works by intercepting calls to distributed objects and executing system code which carries out the process of locating objects and sending data and execution instructions.

The architecture of a distributed objects system:

The main advantage of using a distributed objects scheme lies in the fact that it has a 100 per cent fit with object-oriented technology: that classes identified during the analysis and design phases can be immediately implemented in terms of classes in some programming language, deposited on some remote computer which forms a component of a distributed system and reused without any modification.

The main disadvantage with distributed objects currently being experienced by developers is that their performance, certainly compared with message passing tech- nologies, is inferior.

The mechanisms for developing distributed objects are straightforward and involve either processing source code or an intermediate language.  (Ince, 2002, p0.85-86)

Ince, D. (2002). Developing Distributed and E-commerce Applications (2nd ed.).

What is Serialisation?

In computer science, in the context of data storage and transmission, serialisation is the process of converting an object into a sequence of bits so that it can be stored on a storage medium (such as a file, or a memory buffer) or transmitted across a network connection lnk. When the resulting series of bits is reread according to the serialization format, it can b used to create a semantically identical clone of the original object. For many complex objects, such as those that make extensive use of references, this process is not straightforward.

Advantages of Serialisation

• A method of persisting objects which is more convenient than writing their properties to a text file on disk, and re-assembling them by reading this backin.
• A method of issuing remote procedure calls such as SOAP
• A method for distributing objects, especially in software componentry such as COM, CORBA etc
• A method for detecting changes in time-varying data.

Serializable Object:

To serialize an object means to convert its state to a bite stream so way that the byte stream can be reverted back into a copy of the object. A Java object is serializable if its class or any of its superclasses implements eithe the java.io.Serializable interface or its subinterface, java.io.Externalizable.

When an object is serialized, information that identifies its class is recorded in the serialized stream. However the class’s definition (“class file”) itself is not recorded. It is the responsibility of the system that is deserializing the object to determine how to locate and load necessary class files. For example, a Java application might include in its classpath a JAR file that contains the class files of the serialized object(s) or load the class definitions by using information stored in the directory, as explained later in this lesson.

The following example invokes Context.bind() to bind an AWT button to the name "cn=Button". To associate attributes with the new binding, you use DirContext.bind() . To overwrite an existing binding, use Context.rebind() and DirContext.rebind() .

// Create the object to be bound
Button b = new Button("Push me");
 
// Perform the bind
ctx.bind("cn=Button", b);
You can then read the object back using Context.lookup() , as follows.
// Check that it is bound
Button b2 = (Button)ctx.lookup("cn=Button");
System.out.println(b2);
Running this example produces the following output.
# java SerObj
java.awt.Button[button0,0,0,0x0,invalid,label=Push me]

When a serialized object is bound in the directory as shown in the previous example, applications that read the serialized object from the directory must have access to the class definitions necessary to deserialize the object. Alternatively, you can record a codebase with the serialized object in the directory, either when you bind the object or subsequently by adding an attribute by using DirContext.modifyAttributes() . You can use any attribute to record this codebase and have your application read that attribute from the directory and use it appropriately. Or you can use the "javaCodebase" attribute specified in RFC 2713. In the latter case, Sun’s LDAP service provider will automatically use the attribute to load the class definitions as needed. "javaCodebase" should contain the URL of a codebase directory or a JAR file. (Note that JAR files work only with the Java 2 platform). If the codebase contains more than one URL, then each URL must be separated by a space character. (“Serializable Object”, n.d.)

Reference:

Wikipedia. (2008). Serialization. Retrieved June 07, 2009, from http://en.wikipedia.org/wiki/Serialization

Serializable. (n.d.). Retrieved June 07, 2009, from http://java.sun.com/products/jndi/tutorial/objects/storing/serial.html

1. Serialisation is the process whereby objects are turned into raw data so that they can be sent over a transmission medium.

2. Java distributed technologies such as RMI distributed object technology need to send such objects over a network and hence they need to be able to converted into their raw data.

3. In Java this is done very simply by specifying that a class implements the Serializable Interface

(Ince, 2002, p.83)

Reference:

Ince, D. (2002). Developing Distributed and E-commerce Applications (2nd ed.).

Fixed Protocol: Vocabulary is fixed: it is embedded in the client and server’s code and data does not change.

Example:

1. The protocol describe simple naming service.

2. A banking application might require the balance of an account to be returned for either the name of an account holder or the unique integer key which identifies the account.

Adaptive Protocol: Protocol Changes.

When a client and a server have to negotiate some subset of a protocol which they both understand.

Example:

The Client may only understand an early subset of a protocol while the server understands the full up-to-date version of the protocol. This type of negotiation occurs in client-server systems which form part of multimedia application.

(Ince, 2002, pp.82-83)

Reference: 

 Ince, D. (2002). Developing Distributed and E-commerce Applications (2nd ed.). 

Such a service is a type of very flexible, naming service which contains data about the resources and users of a distributed system. (Inc, 2002, p.82)

For Example:

If you want to write a program which discovers what the fastest printer is in a distributed system then the program will consult a directory service.

Reference:

Ince, D. (2002). Developing Distributed and E-commerce Applications (2nd ed.).

1. Message passing is the simplest form of development paradigm

2. Message passing is based on the idea of a protocol: a language which embodies the functions required by one entity in a distributed system (usually a client) which another entity provides (usually a server).

(Ince, 2002, p.80)

3. Central idea behind the message passing paradigm is: it involves an architecture in which clients and servers comunicate using communication lines

4. In general message passing is used in applications which satisfy one or more of a number of criteria:

• High performance is required; message passing is a much more client mechanism. However programming is complex.
• Rapid implementation is required, for example an e-commerce application mybe required quickly in order to react to a competitor’s new website; if here is no time to carry out sophisticated design and you are prepared to countenance the inevitable errors that this brings, then a message passing solution might be chosen.
• The system uses a technology that no existing protocols will communicate with.  (Ince, 2002, pp.83-84)

Reference:

Ince, D. (2002). Developing Distributed and E-commerce Applications (2nd ed.).

Synchronous message passing: Involes one entity (usually a client) in the message passing process sending a message and a second entity (usually a server) receiving it, carrying out some processing and then sending back some reponse which the first entity processes in some way. While the second entity is carrying out the processing the first entity pauses waiting for the response. (Ince, 2002, p.83)

Asyncronous Message Passing: Each entity in the process does not have to wai for the next part of the dialogue they are engaged in and can carry out some other task. For Example: the server could be carrying out some processor-intensive task for another service which it provides. This form of message passing, where there is no close coordination between message passing entities. (Ince, 2002, p.83)

Reference:

Ince, D. (2002). Developing Distributed and E-commerce Applications (2nd ed.).

1. University Enrolment: look at our school enrolment website. There are few security features:
a. Students user name and password for login
b. Every 3 months need to change the password
c. Login attempts limitation

2. Online Shopping:
The credit card security system.

SmartAsset ODC wins Microsoft OBA Solution of the Year 2008 Award.

The Online Workshop is delighted to announce that its SmartAsset Office Deployment Capability has won the inaugural world-wide Office Business Applications Solution of the Year Contest. The objective of the contest was to recognize excellence in Office Business Applications solutions developed by Microsoft partners. Round 1 of the contest was based on hits to the solution web-site. Thanks to those of you who voted for us in this manner. Round 2 was based on the evaluation criteria including:

• Use of Microsoft Office 2007 products
• Completeness of OBA Central solution description
• Uniqueness of solution in the marketplace
• Innovation exhibited in this solution
• Potential business impact of this solution

Full solution details for SmartAsset ODC as provided to OBACentral can be viewed at http://www.obacentral.com/en/solutions/pages/solutiondetails.aspx?solutionid=5471

The winner was announced at the Microsoft Office Developer抯 Conference 2008 which was held at the San Jose Conference Center in California. The Online Workshop also exhibited SmartAsset at this conference. Click here to review a comprehensive trip report.

SmartAsset ODC enables deployment of comprehensive asset management functionality within the Office 2007 suite of products. Activities such as asset navigation, maintenance planning, task assignment, job execution and feedback, parts utilisation, time recording and presentation of analytical data can be performed using tools such as Outlook, Projects, Excel and Word. The underlying asset data can be sourced from a self-contained SmartAsset SQL Server database or from the asset management modules of other products, including ERPs such as SAP.

The ICT Sector

The Australian information and communications technology (ICT) sector is a dynamic industry spanning a diverse array of businesses in areas from computer hardware and software, networking and communications to the Internet, telecommunications, multimedia and more.

As technology becomes ever more entrenched in our modern lifestyle, enabling every aspect of commerce, government, education, communications and entertainment, the ICT sector is playing an increasing role in driving economic growth and prosperity, accounting for 4.6% of GDP and 13.8% of total investment in Australia.

According to the Australian Bureau of Statistics (ABS), ICT makes a greater contribution to the economy than agriculture, forestry and fishing, defence and education.

ICT Driving Productivity

A report released in March 2006 by the Department of Communications, Information Technology and the Arts (DCITA) also highlighted the importance of ICT as the main technological driver of productivity growth.

The report, entitled Forecasting productivity growth: 2004 to 2024, forecast that Australia will continue to benefit from the strong technological momentum in ICT and its many applications for the next two decades. Growth is particularly expected in areas that are already heavy users of technology, such as finance, manufacturing, telecommunications and trade.

The ICT Landscape

In 2002-03, the Australian ICT sector comprised around 24,000 companies which together achieved revenues of almost $80 billion, according to the ABS. Computer services businesses dominate the industry at 77 per cent, followed by whole trade companies (8 per cent). A significant percentage of these revenues related to imported products, with locally produced goods and services valued at $49.1 billion during the same period.

The vast majority (over 95 per cent) of ICT businesses are small, employing fewer than 20 people. Around 68 per cent of ICT workers are male, with men dominating technical and professional roles (79 per cent). A range of initiatives have been developed to encourage more women into the ICT workforce, including a number spearheaded by the ACS.

Foreign ownership is high, with multinational companies accounting for 43 per cent of all employment in 2001, and earning 60 per cent of industry income.

Geographically, NSW and Victoria are the main focus for ICT business, employing roughly three-quarters of Australian ICT specialists, however the ACT, Queensland and WA have each achieved substantial growth in recent years.

Imports and Exports

Australia imports ICT goods primarily from Asia and Europe, with the main sources for 2004-05 being China ($4.2 billion), Malaysia ($1.7 billion), Republic of Korea ($1.25b), Singapore ($1.1b), Taiwan ($1b), Japan ($1b), Thailand ($361 million), Hong Kong ($321m), Germany ($308m) and the UK ($258m).

Australia’s largest export market continues to be New Zealand ($648 million), followed by the United States ($262m), Singapore ($125m), Hong Kong ($85m), the UK ($80m), Germany ($79m), India ($67m) and China ($57m).

Employment

In terms of employment, there were 274,132 people employed by Australia’s ICT industries at the end of June 2005, according to the ABS.   ICT specialist  business accounted for 89.1 per cent of this employment.  The business groupings employment the most people were computer services (41.1 per cent), telecommunications services (27.1 per cent), and wholesale trade (24.6 per cent).

Across the wider economy,  the ABS  Labour Force Survey  recorded 371,150 people employed in ICT related positions in August 2006. This consisted of 253,850 people in direct ICT roles (including IT managers, computing professionals and computing support technicans) and 117,300 in  ”engineering and trades” occupations.   91.8 per cent fo these people were employed full-time.

Of these ICT employees, 84.5 per cent were male and people under 30 years of age make up 27.7 per cent.

Raising Professional Standards

The ACS is the recognised professional association for the Australian ICT sector, representing the views of technologists to government, industry and the community.

The ACS believes that Australia’s future prosperity is totally dependent on ICT professionalism. True professionalism, and its underlying commitment to a Code of Ethics and Code of Professional Conduct and Practice, continuing knowledge and skills development, demands a level of excellence, rigour, integrity and honesty that must represent a key competitive advantage.

In mid-2006, the ACS initiated the Technologists in the Public Interest (TIPI) program, which is designed to build public trust and business confidence in the ICT profession. Through TIPI, the ACS seeks to create a stronger identity for ICT professionals and to introduce recognised minimum standards and certifications for those working in safety-critical or high risk areas such as security.

While it is unusual for an industry to seek self-regulation for itself, the ICT profession believes this is the best way to raise professional standards and ultimately to boost confidence in ICT.

In the absence of a nationally-recognised certification, the ACS believes that choosing security professionals who are members of a professional association – and bound by a code of ethics and conduct as well as being committed to their own professional development – is a legitimate risk mitigation strategy.