Bruno Pereira

Publiquei hoje um artigo bem detalhado sobre web services REST.

Para os interessados, o artigo está aqui.

Deixei os comentários habilitados em todas as páginas, para que todos possam fazer críticas, sugestões de conteúdo, postar dúvidas, entre outras coisas.

Pretendo publicar aqui vários outros artigos técnicos sobre web services, integração, SOA e tópicos relacionados. Caso vocês tenham sugestões ou idéias interessantes para discutir, já sabem onde me encontrar

Li hoje um post do Dare Obasanjo que me chamou a atenção por mostrar como a web é mesmo um quintal aberto, onde nossas informações pessoais ficam cada vez mais expostas a qualquer um que queira mesmo procurar.

Recentemente a senha do e-mail pessoal de Sarah Palin no Yahoo foi roubada, e o suposto responsável mandou e-mails para algumas listas, dizendo como conseguiu fazer isso com facilidade. Sarah Palin é a atual governadora do Alaska, e candidata a vice-presidente dos Estados Unidos, na chapa de John McCain.

Segundo o hacker, no processo de recuperação de senha do Yahoo foram feitas algumas perguntas pessoais da governadora, mas o hacker foi capaz de obter TODAS as informações solicitadas com alguma facilidade na internet, em diferentes locais.

Isso mostrou que a funcionalidade de recuperação de senha da maioria dos sites é inadequada, por ser insuficientemente segura. Dare Obasanjo sugeriu uma alternativa simples - que provavelmente muitos de nós já havia pensado - que é permitir ao usuário que cadastre sua própria pergunta secreta, em vez de utilizar uma das poucas perguntas oferecidas pelos sites.

Bom, felizmente meu time é responsável pelo cadastro de usuários na Globo.com e muito em breve faremos uma nova Central de Relacionamento. Dentro das modificações a serem feitas está um novo processo de recuperação de senha, no qual certamente faremos algo melhor do que há hoje.  Atualmente também utilizamos um conjunto limitado de perguntas pré-cadastradas, mas vou fazer todo o possível para convencer nosso PO de que precisamos de algo melhor que isso

Yesterday the JSR-311 (Java API for RESTFul Web Services - JAX-RS) was finally approved!

I’m using Jersey (the JSR’s reference implementation) for more than 6 months and I was anxious to have the specification approved.

In my team we’re currently using Jersey 0.7 in production, and were waiting for the JSR to be approved to analyse the final version of its implementations. Now we’ll wait for both Jersey and JBoss RESTEasy to release their final versions and we’ll analyse both to see which one we’ll use in our RESTFul services.

If anyone wants to give me good reasons to use either one of the implementations, now it’s the perfect time! I’m hearing…

After some extra effort today, I did manage to get WSO2 Registry working in JBoss 4.0.5

The huge amount of jdbc error messages in the server logs were not actually errors. JBoss datasources have a configuration element called <track-statements>. When this option is turned on, JBoss logs massively when there are Statements or ResultSets that are left open. The application server closes the Statements and the ResultSets, and shows many many logs indicating this. The log messages I was seeing were not errors in the Registry, they were only JBoss warnings.

All our datasources in my team have this option turned on, and we always take care to close the ResultSets and Statements in all our applications. But since the server closes the ResultSets and Statements, I can live with the way the Registry does

I had to do some things to get the Registry working in JBoss. First, I had to remove the log4j the Registry had packed inside its war file. Our JBoss servers use the Unified Classloader, for several years already. This setup was there before I even joined the company, and it’d complicated to change this now, because it’d make us modify several applications. Not being able to change the Classloader, the log4j packed inside the Registry (1.2.13) would conflict with the one present in JBoss itself (1.2.8), so I had to remove it from the Registry’s war. The application worked just fine using log4j 1.2.8, so it’s ok to do this.

After fixing this, I had to enable Java 1.5 code in the jsps. JBoss by default does not allow Java 1.5 code in the jsps, and to modify this, I had to uncomment the code below inside JBOSS_HOME/server/default/deploy/jbossweb-tomcat55.sar/conf/web.xml:

<init-param>
<param-name>compilerSourceVM</param-name>
<param-value>1.5</param-value>
</init-param>

This init-param belongs to <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>, and solves the jsp compilation problem.

Well, that’s what I had to do to make WSO2 Registry work in JBoss. Most of the problems I faced were not Registry’s fault, so I’m sorry for having a wrong impression after some setup problems this week.

I’m currently integrating WSO2 Registry in our architecture and once I finish, I’ll document our architecture here, so that other people can see what uses we’re making of the product.

Well, as I said recently, we want to use a registry to keep URIs of our services and also some configurations that are currently in properties files.

After looking better at WSO2 Registry, I figured out how to do what I need with the product. I had a very short time to evaluate properly WSO2 Registry and Mule Galaxy before my last post, but after another evaluation of them, I concluded I can use them in this case.

Last week I developed a Java client to consume my publications from WSO2 Registry. It wasn’t much fun to develop, because I had to make it compatible with JDK 1.4. This prevented me from using their client API, which runs only on JDK 1.5 and above.

Since I had to use JDK 1.4, I used XStream for my Java <-> XML mappings. Not being able to use the Registry’s Java client, I also had to consume data from their AtomPub API. I used Apache Abdera 0.3 for this task, which was their last version supporting JDK 1.4 (through retroweaver).

So far so good. Last week I had a prototype client consuming stuff from the Registry, so I moved on to some other tasks. Well, today I started integrating the Registry in my application. That meant moving from Tomcat 6 to JBoss 4.0.5. And that’s when I got in trouble.

Unfortunately I hadn’t seen this page before. It turns out that the only application server they have tested enough is Tomcat. And not any Tomcat, only Tomcat 6. Since their distribution format is a .war file, I never would think they support only Tomcat. In their download page it says: “This distribution includes the Webapp module with relevant JAR files and other resources to be deployed in the servlet container, providing a Web UI and an APP interface.”

Well, I’m probably just dumb. They didn’t say “a servlet container“. They said “the servlet container“. This certainly means “the servlet container we support, which is Tomcat 6″. But this is not written there, so dumb people like me will be subject to mistakes.

“Heck, this is open source, I’m gonna make it work on JBoss!”. This was my first thought. And then I started setting up the Registry in JBoss, right after lunch today.

The first thing I noticed is that the Registry packs a newer version (1.2.13) of log4j than the one present in JBoss (1.2.8). This shouldn’t be a problem, but anyone who has experienced some of the JBoss Classloader Hell knows that it’s not a wise decision to bring a newer version of log4j inside your application if you’re going to run on JBoss. This is not a Registry fault, so I gladly fixed the problem by removing the log4j they had packed inside the .war file.

After fixing this, I was gettings errors trying to open the Registry’s index page on JBoss. I quickly found out that their jsps had scriptlets using JDK 1.5 code, and JBoss was not able to compile the jsps. This was easy to fix by uncommenting a init-param in the web.xml in the Tomcat module inside JBoss. However, the amount of scriplets inside their pages was the first symptom that something didn’t smell right.

After fixing the jsp problem, I configured the Registry to connect to MySql through a JBoss datasource. I then could open their index page and even use some features. However, when I started checking the server logs I was shocked. A huge amount of errors in jdbc operations. I had no clue of what was going wrong, because the UI was apparently working normally and the database was being manipulated.

Well, since it’s an open source product, I promptly checked out their code and started looking for problems. Most errors occured in simple jdbc operations like the creation of a prepared statement. The application logs were not very helpful, and I couldn’t figure out where the problem was.

However, something scared me a lot. Between the zillions of jdbc errors, I saw JBoss screaming for help, saying that the PreparedStatements were left open. I went to look at their jdbc code, and it definitely needs care. There were a LOT of jdbc operations inside try/catch blocks, where they treated SQLExceptions. I didn’t see the finally blocks closing the PreparedStatements and the ResultSets. This explains JBoss’s complaints about the PreparedStatements.

After several hours trying to use WSO2 Registry inside JBoss and looking at their code, I must say I am VERY discouraged to put anything in production right now using the product.

I just downloaded Mule Galaxy and now I’m gonna try to integrate it in my application. A very good sign is that they say I can use it with ANY servlet container, including Tomcat and Jetty. I think it’ll be a successful effort, but it’s hard to say anything after my problems with WSO2 Registry today.

But knowing Dan Diephouse’s work for several years, I’m pretty confident in this new attempt. I’ll post the results later this week.

Foram publicados os vídeos da minha palestra de REST no aniversário do CEJUG, no dia 16/09/2008. Eu os coloquei embutidos abaixo para facilitar a visualização por parte dos interessados.

Deixo enormes agradecimentos ao René por ter filmado e pelo esforço heróico de publicar todos esses vídeos no Youtube, para que todos tivessem acesso.

Como ainda sou um palestrante amador, todo feedback será bem-vindo, para me ajudar a progredir aos poucos.

Como eu havia falado, esta terça-feira eu me apresentei no evento do aniversário do CEJUG.

Foi uma ocasião muito legal. Além de conhecer a rapaziada do grupo, eu também conheci a cidade de Fortaleza e já voltei para casa querendo retornar mais vezes ao Ceará. Do CEJUG eu conheci o Rafael Carneiro, Silveira,  Milfont, Tarso, Rafael “Foquinha” Ponte, Handerson, Igo, René, Paulo, Tales, Marum e mais alguns que eu esqueci o nome

Como eu já esperava o pessoal me recebeu muito bem e foi muito bacana conhecê-los pessoalmente. Além disso, já sou agora conhecedor de uma vasta gama de termos genuinamente cearenses :)  Diabéisso maxo!

Além de conhecer o pessoal do CEJUG, também tive a oportunidade de conhecer o Maurício Leal e o Kohsuke, ambos da Sun. Ambos são muito simpáticos e me passaram uma idéia legal de bastante coisa que está rolando na Sun.

O Kohsuke é também provavelmente o cara de mais prestígio técnico que já conheci, pois é nada menos que o criador do Hudson e um dos principais responsáveis pelo JAXB e pelo Glassfish v3. Inclusive uma das coisas mais marcantes da participação dele no evento foi trazer a todos o desejo de conhecer melhor o Glassfish e acompanhar as grandes novidades prometidas para esta nova versão. Uma das coisas que mais me interessou é a arquitetura modular com o Osgi. Eles estão apostando no Osgi junto com o Eclipse, e isto me trouxe a curiosidade de conhecer mais detalhes da tecnologia.

Bom, para destacar ainda mais a hospitalidade do pessoal, eles ainda me deram uma cesta recheada de ítens característicos cearenses. Gostei bastante dos presentes e quem quiser degustar a mais pura Ypioca aqui no Rio é só falar comigo

O evento em si foi bem legal e ainda teve uma banda animando o intervalo. Os coitados deram o azar de tocar logo na hora que o povo foi correndo comer, mas quem ficou assistindo curtiu bastante

Depois das palestras, bastante gente foi na confraternização e a bagunça lá foi até depois de meia-noite.

Para finalizar, eu gostaria de agradecer a todo o pessoal da organização lá em Fortaleza e também ao Gaúcho e ao Hildeberto por fazerem um evento tão legal e continuamente levar o CEJUG às cabeças. Esse tipo de comunidade traz uma enorme força ao mercado de software nacional e seria excelente que tivéssemos outros grupos com tanta energia como o do Ceará. Agradeço muito pela oportunidade e deixo meus parabéns à comunidade de software cearense!