Os web services WS-* possuem o WSDL (Web Services Description Language), um artefato amplamente aceito que descreve de forma padrão os serviços da aplicação. Ao especificar no WSDL quais são os schemas XML dos documentos que serão trocados e a cardinalidade precisa de cada elemento, conseguimos garantir que qualquer cliente que entenda o padrão estabelecido será capaz de interpretar os documentos e comunicar-se corretamente com os serviços. Além disto, a maturidade deste padrão traz a vantagem de que já existem geradores de clientes em várias linguagens a partir de um documento WSDL.

Entretanto, WSDL (bem como muita coisa em WS-*) é complexo. Um ser humano que tenha que analisar um WSDL grande perderá um bom tempo para entender o que está descrito no documento. Já REST não tem uma forma padrão de especificar os contratos dos serviços.

Embora a versão 2.0 da especificação WSDL permita descrever web services REST, os principais projetos open source da área como o Apache Abdera, Google Data API, Jersey e o Mule não utilizam esta forma de publicação. Não tenho conhecimento de nenhum projeto publicamente divulgado que faça uso do WSDL 2.0 para descrever serviços REST, e a adoção desta capacidade é baixíssima (se é que existe).

O projeto Jersey oferece opcionalmente o WADL, que é uma forma de descrever serviços REST. Confesso que ainda não olhei o WADL para ver se seria interessante usá-lo. Pelo que sei, entretanto, a adoção dele também é muito baixa.

Existe também o documento de serviços do AtomPub, que é bem interessante. Ele é um documento simples que lista quais são as coleções disponíveis e a localização das mesmas. O documento informa também quais são os MIME types aceitos em cada coleção.

Eu considero interessante que a aplicação ofereça uma interface simples de consulta dos serviços disponíveis. Não é obrigatório, mas quando a aplicação tem uma certa quantidade de clientes é bem legal ter isso para facilitar.

Em dois projetos que eu trabalhei, eu implementei um Servlet simples que listava todas as URIs disponíveis na aplicação, quais métodos HTTP são aceitos em cada uma das URIs e além disso um exemplo de XML manipulado em cada uma das URIs. Isso foi algo que eu achei bom o suficiente, e não tão custoso. Normalmente a documentação de verdade dos serviços fica em algum lugar como uma Wiki, ou uma página qualquer com a descrição detalhada de como interagir com os serviços.

A questão principal é que quando você segue as boas práticas de desenvolvimento REST, os seus serviços ficam muito mais claros para quem precisa se integrar. Por exemplo, eu trabalhei em um projeto crítico de integração com o Google esse ano. Tive que usar várias funcionalidades da Google Data API. A API deles é REST, e encapsula os dados com o formato Atom. Eles não oferecem nenhuma interface semelhante ao WSDL, eles simplesmente têm uma página com a documentação dos serviços.

Como eles seguiram as boas práticas de implementação REST, eu rapidamente aprendi a utilizar a API deles. Os protocolos de comunicação REST são bem semelhantes, e mais simples de entender do que qualquer coisa com WS-*. Pouco mais de 1 hora depois de olhar a documentação deles, eu já estava conseguindo me integrar com eles, com os primeiros exemplos.

O Guilherme fez uma observação interessante durante a discussão disso na minha apresentação no Tech Talk. Quando você segue as boas práticas e implementa um protocolo conciso e claro, de certa forma podemos dizer que a implementação se "auto-documenta". É algo que podemos traçar um paralelo ao que acontece ao utilizarmos Domain Driven Design. Aproximando a linguagem do código do domínio de negócio, facilitamos a compreensão da aplicação por pessoas que nunca a tinham visto antes. Uma boa arquitetura de web services declarativos (REST) fica muito mais clara do que uma arquitetura de web services imperativos (WS-*). Isto acontece porque com REST o que fica em destaque são os Recursos (que representam conceitos claros do domínio), em vez de Operações.

É claro que as pessoas ainda terão que ler um pouco da documentação, mas como os conceitos em sua maioria já estarão "no sangue", as dificuldades iniciais são menores do que com WS-*.

O Felipe Gaúcho comentou no CEJUG sobre a capacidade de gerar clientes automatizados com WSDL. Embora isso seja verdade, no meu ponto de vista isso é meio que um mito. Não conheço ninguém que faça integrações automatizadas sem depender de seres humanos. A motivação disso é clara. Integrações envolvem regras de negócio, e ninguém que eu conheço faz negócios automáticos, sem definir as regras :)

Existia o mito de que as aplicações "descobririam" serviços automaticamente com UDDI e se virariam para fazer as integrações, gerando os clientes automaticamente. Embora isso seja tecnicamente possível, na prática isso pra mim é uma viagem que serviria mais para desenvolvimento de inteligência artificial do que para web services propriamente :)

Embora esta precisão do WSDL seja um ponto positivo, eu tenho a convicção de que a clareza que temos ao usar REST supera e muito as vantagens de termos geradores de clientes automatizados. Quanto a WS-* x REST de uma maneira mais geral, tem uma frase que eu gosto de utilizar. WS-* é apenas overhead a não ser que você tenha informações relevantes nos seus cabeçalhos SOAP. Se você nunca se preocupou MUITO (veja bem, MUITO) com o que está indo nos seu cabeçalhos SOAP, provavelmente um protocolo REST seria mais interessante.

Tem uma opinião a respeito disso? Estou ansioso para conhecê-la! :)

Amazon's business model is different than a traditional software company that often spends 18-24 months convincing customers to adopt new hardware/software or services. Amazon is leveraging a different computing model based on providing customers will a set of predefined services that can be bought without making a long term commitment. In a sense, Amazon has had the luxury (or good sense) to roll out service after service and see what sticks. As Jeff sees it, "people's brains light up. They can build their business and applications in a positive way without having to worry about bandwidth, power and cooling." His perception is that customers don't think about whether the cloud provided by Amazon will support their needs. Clearly, he is able to talk this way because Amazon has made the investment in a scalable architecture to support an infrastructure that is designed for massive scalability. The other issue is that having built this architecture for its own retail requirements, Amazon had the foresight to exploit the technology to create a new line of business -- in essence, a compute cloud based on providing a set of tools and product offerings to the market. The message to the market is straight forward, use these services so that you can innovate quickly without having to build from scratch. In taking this approach, Amazon creates both a test bed that allows the company to collaborate on new functionality with partners. In addition, and perhaps most importantly, it allows customers to buy incremental capability so they can scale up and down when they need to. According to Jeff one of the benefits of the cloud is that it isn't dominated by the needs of one customer. In other words, one customer may have a spike in demand while another has less need at that point in time. Over the years, Amazon is able to understand usage patterns that are predictable.

Amazon's business model follow this approach. A customer creates an account with Amazon that in essence gives them a charge account with Amazon. Customers get access to all of the Web services APIs. Their usage is tracked and they are billed for what they use. The business model is quite straight forward. Amazon charges 15 cents per gigabyte per month -- not a lot of money even when you scale. What is interesting to me is there is no contracts to negotiate -- everyone understands the rules. I asked Jeff if customers ever ask to buy a "private cloud". While Amazon has been asked by customers, Jeff felt that because of the amount of experience that Amazon has with its hosted services discourages customers from explaining, "This is a business we want to be in. We have a lot of experience in our organization. We build highly cost effective data centers and sophisticated monitoring and operations." He contends that Amazon has the expertise based on its 13 years in the business is enough to keep customers from walking away from its cloud. If you do the math, it would be difficult to argue. For example, if a customer needed 500GB of storage for two years, the cost would be $1800. In addition, it avoids the requirements for managing that environment.

Jeff makes a good point. If a customer needs to scale from 10GB to 100 TB in a month it might be hard to pull off. "This is routine for us," Jeff claims. From his vantage point, the cloud changes the relationship between the customer and their hardware vendors. In effect, customers are sharing hardware resources with lots of other customers. So, the question becomes, who is your partner? It is no longer the provider of the hardware or the operating system. You probably still have a relationship with your software provider.

So, Amazon's view of the cloud is pretty straight forward -- it is a way to get value out of virtualization. Jeff points out that if developers uses Amazon's elastic cloud service, for example, they pay to access servers on an hourly basis. Amazon allocates server to that account, provides a copy of the operating system they need to get started. That process takes a few seconds.

Another dimension of Amazon's business revolves around the companies that actually build applications that sit on its infrastructure. Amazon has built a bunch of its own applications that it offers as services. In addition, there are a number of application companies that are building applications on top of the Amazon platform. One that Jeff mentioned to me is called RightScale, an automated cloud computing management system intended to help customers of Amazon's Elastic Compute Cloud with issues such as load balancing. In addition to this type of company there is a community of 370,000 developers. Because Amazon sets the barrier to use so low, it is easy for a developer to try a service without making a long term commitment.

The more I think about Amazon's platform and business model, the more sense it makes to me. I believe that Amazon and others such as Google, Salesforce.com, and eBay are a peak into the future of the new generation computing. In a sense, this model breaks every rule that the traditional computing industry has been built on. This movement towards enterprise software as a service and utility computing is beginning to redefine hardware, software, management and services. I predict that this new business model is going to slowly but surely turn the industry upside down. It isn't only that the business model is different. The underlying technology platform based on standards and a service oriented architecture is propelling this change. The only thing that will slow this transformation is fear of change. But what else is new.

The NNDB Mapper is a visual tool for tracking the connections of more than 32,000 famous people- linking them together through family relations, corporate boards, tv shows, political alliances and shadowy conspiracy groups.

Creating a map with the NNDB Mapper tells a story about the world through connecting the lives of billionaire executives, scientists and inventors, politicians and activists, writers and musicians, and even Hollywood stars.

These stories are shared by saving the maps for others to explore- from San Francisco's political landscape, to Hollywood sex charts, to who rocks more: Ozzy vs Slayer?

Technical Book
Almost Finish Reading
Web Services : Author by Gustavo Alonso, Fabio Casati, Harumi Kuno, and Vijay Machiraju.

Comment : This book is really good for people who are new to web services and references as well. It explain the history of System architecture to current web services. Since this book is kind like a bit extreme technical like RFC specification and no practical solution at all. It introduce SOAP, WSDL, UDDI, 1 to N tier architecture, web service compsition, BPEL, WS-Security, WS-transaction, WS-routing, and more ws-*.

The first 1-4 chapters were about the enterprise system era before web services was introduced. You can got a big picture why integration and interoperability was so hard at that era.
Chapter 5-6, slowly walk through the needs of web services and chapter 7-9 were mainly about web service composition and BPEL was introduced.

Although i finish reading this book, i only get half of its content because this book was too technical for beginner. You had to understand each design behind the system before proceed to the next chapters. If you want to learn web services and don't know where to start, then this book might help you.

By Web Services India

• 1) English version:

In Greece very few companies are active in Semantic Web technologies. Some Greek university research has started, of course, part of which is regularly being reported and explained in non-technical terms through the blog of Greek university professor Gregory Mentzas (highly recommended).

However, on the whole, Greek Semantic Web activity is more-or-less negligible or -even- non-existent, at the moment. In contrast, another Balkan country, traditionally very skilled in mathematics and computer science, is plunging ahead much faster into the Semantic Web: Bulgaria!

"OntoText" is a Bulgarian software house, founded by "Sirma Group" in Sofia. It has another department based in Canada. OntoText is "focused on research and core technology development for knowledge discovery, management, and engineering, Semantic Web and Web Services".

"Sirma Group" is led by the following people (of typically Bulgarian names):

Board of Directors
Georgi Marinov – Chairman
Chavdar Dimitrov - Vice chairman
Tsvetan Alexiev - CEO
Atanas Kiryakov
Vesselin Kirov
Yavor Djonev
Krasismir Bojkov

Executive Team
Tsvetan Alexiev - Executive Director
Anatoly Apostolov - Director, Finance
Chavdar Dimitrov - Director, Admin. & HR
Anton Gavrailov - Director, Business Dev.
Vesselin Kirov - Director, R&D
Vladimir Alexiev - Director, Technology

• 2) in Greek / ΕΛΛΗΝΙΚΑ:
  

Στην Ελλάδα πολύ λίγες εταιρείες έχουν αναπτύξει δραστηριότητα στις Τεχνολογίες του Σημασιολογικού Ιστού. Κάποια Ελληνική πανεπιστημιακή έρευνα έχει ξεκινήσει βέβαια, ένα μέρος της οποίας εκλαϊκεύεται μέσα από το blog του καθηγητή κ. Γρηγόρη Μέντζα (που το προτείνω ανεπιφύλακτα).

Παρόλ' αυτά και παρά τις επιδοτήσεις της Ε.Ε. που συνήθως... πάνε στράφι όταν δεν... τρώγονται - (ΔΕΝ το μετάφρασα αυτό στα αγγλικά :) ) η Ελληνική Δραστηριότητα στον Σημασιολογικό Ιστό είναι (λίγο-πολύ) αμελητέα, σχεδόν ανύπαρκτη αυτή τη στιγμή! (ΦΤΟΥ σας μ......! - ΟΥΤΕ αυτό δεν το μετάφρασα).

Αντίθετα, μία άλλη Βαλκανική χώρα, παραδοσιακά με πολύ ισχυρά ταλέντα μαθηματικών και πληροφορικής, προχωράει με πολύ πιο γρήγορα άλματα στον Σημασιολογικό Ιστό: - Η Βουλγαρία!

Η εταιρεία "OntoText" είναι Βουλγαρικό software house που ιδρύθηκε από τη "Sirma Group" στη Σόφια. Έχει ένα άλλο παράρτημα που εδρεύει στον Καναδά. Η OntoText "επικεντρώνεται σε έρευνα και ανάπτυξη βασικής τεχνολογίας για την (αυτοματοποιημένη) Ανακάλυψη Γνώσης, το management και τη Μηχανική, στον Σημασιολογικό Ιστό και τις (σχετικές) υπηρεσίες Web ".

(λίστα ηγετικών στελεχών της εταιρείας δόθηκε στα Αγγλικά).

.

By Web Services India

By Web Services India

It's proven that websites designed using Flash technologies are much more attractive than static HTML websites. And an eye-catching website is always more profitable than one that is not. As long as your website is developed by a professional graphic design company, you can rest assured that it will be a success. Log team comprises professional graphic designers and trained web developers with the necessary skills to understand your and your target's needs.

By Web Services India

It's proven that websites designed using Flash technologies are much more attractive than static HTML websites. And an eye-catching website is always more profitable than one that is not. As long as your website is developed by a professional graphic design company, you can rest assured that it will be a success. Log team comprises professional graphic designers and trained web developers with the necessary skills to understand your and your target's needs.

By Web Services India

It's proven that websites designed using Flash technologies are much more attractive than static HTML websites. And an eye-catching website is always more profitable than one that is not. As long as your website is developed by a professional graphic design company, you can rest assured that it will be a success. Log team comprises professional graphic designers and trained web developers with the necessary skills to understand your and your target's needs.

By Web Services India

Hewlett-Packard has struck a $13.25 billion deal for Electronic Data Systems Inc. And — shocker! — neither Goldman Sachs or Morgan Stanley is on the deal.

Instead, Citigroup and Evercore Partners advised Electronic Data on the deal, while J.P. Morgan Chase and Lehman Brothers advised Hewlett-Packard.

And, since there hasn’t been a really juicy technology deal in quite a while — read all the details about this one here — Deal Journal is mentioning the bankers by name. Evercore’s Roger Altman, William O. Hiltz and Naveen Nataraj worked with Citigroup’s Ray McGuire, Ben Druskin, Michael Tedesco, Ed Wehle, Brian Mass and Melissa Knox. (Deal Journal Trivia: Druskin was just promoted last week to co-head Citigroup’s global technology, media and telecom advisory group.) J.P. Morgan’s team included Doug Braunstein, Karl Will, Will Thiessen, Mark Zanoli and Curt Sigfstead. At Cleary Gottlieb Steen & Hamilton, Hewlett-Packard’s legal adviser, the lead partners were Christopher Austin, Benet O’Reilly and Victor Lewkow.

Read Full News

Resources for

Bad Boys Computers

Web start-up unveils semantic Wikipedia search tool

SAN FRANCISCO (Reuters) - Powerset on Sunday unveiled tools for searching Wikipedia that use conversational phrasing instead of keywords, marking the first step of its challenge to established Web search services such as Google.

Powerset's technology breaks down the meaning of words and sentences into related concepts, freeing users from always needing to type the exact words they want to find.

The closely watched Silicon Valley start-up is offering a way of searching millions of entries in Wikipedia's online encyclopedia, helping users find detailed answers to questions rather than isolated links that require further research.

Read Full News

Resources for

Bad Boys Computers

By Web Services India

2. When dealing w e-commerce

3. Decreasing costs

4. Increase profits

5. Understanding that profits is not the same as sales

6. Expands the size of the market from regional to national or national to international

7. Contract the market

8. Reach a narrow market

9. Target market segmentation allows you to focus on a more select group of customers

10. And therefore have a competitive advantages in satisfying them

By Web Services India

2. When dealing w e-commerce

3. Decreasing costs

4. Increase profits

5. Understanding that profits is not the same as sales

6. Expands the size of the market from regional to national or national to international

7. Contract the market

8. Reach a narrow market

9. Target market segmentation allows you to focus on a more select group of customers

10. And therefore have a competitive advantages in satisfying them

By Web Services India

By Web Services India

By Web Services India

2. When dealing w e-commerce

3. Decreasing costs

4. Increase profits

5. Understanding that profits is not the same as sales

6. Expands the size of the market from regional to national or national to international

7. Contract the market

8. Reach a narrow market

9. Target market segmentation allows you to focus on a more select group of customers

10. And therefore have a competitive advantages in satisfying them

By Web Services India

Book review: Keeping door open for Internet innovation

If asked to pick a favorite piece of consumer technology, who wouldn't choose an iPod over a personal computer?

It does the thing it is designed to do -- play digital music -- very well. It's not like the PC, which may be endlessly adaptable but is not optimized for any single use, is difficult for the nontechnical person to control, and may be exposed to spam, viruses and cyber-criminals.

That choice, according to Jonathan Zittrain, professor of Internet governance and regulation at Oxford University, could be fateful for the future of the Internet and, ultimately, the open society it helps sustain.

Our iPods -- and other devices such as PlayStations, BlackBerrys and TiVo digital video recorders -- are all well and good, but if that were all we had to connect to the Internet, the world would be a poorer place.

In "The Future of the Internet -- and How to Stop It," that is precisely the future that Zittrain sees, although he prescribes a set of somewhat idealistic-sounding remedies to prevent it from coming to pass.

Read Full News

Resources for

Bad Boys Computers

Even though everything seemed to fit, we got an error message back from the service:

After digging around on a number of blogs, forums and Information Centers, we found the issue: The WS-Addressing namespace. WSE 3.0 sets the WSA-ns to:
http://schemas.xmlsoap.org/ws/2004/08/addressing

while WMB 6.1 uses:
http://www.w3.org/2005/08/addressing

Since the WS-Addressing feature cannot be configured we decided to contact the developer of the web service to see if he can change the namespace (or perhaps remove WSA altogether). As a last resort we'd probably have to download Axis (which is used by WMB when communicating with web services) and change the namespace constant. An update is soon to come..

Yet the information and communications technology industry - or ICT - is responsible for the same amount of carbon dioxide emissions as those from planes.

Each year, both sectors emit 2% of total CO2 emissions, though there are signs that the ICT industry is changing.

"In fact, there has been a radical shift in the industry," insists Randy Allen, a vice-president at computer chip firm AMD.

Read Full News

Resources for

Bad Boys Computers

The intent of web design is to create a web site (a collection of electronic files residing on one or more web servers) that presents content (including interactive features or interfaces) to the end user in the form of web pages once requested. Such elements as text, forms, and bit-mapped images (GIFs, JPEGs, PNGs) can be placed on the page using HTML, XHTML, or XML tags. Displaying more complex media (vector graphics, animations, videos, sounds) requires plug-ins such as Flash, QuickTime, Java run-time environment, etc. Plug-ins are also embedded into web pages by using HTML or XHTML tags.

By Web Services India