Java Web Services Developer Pack (Java WSDP) 1.5

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January 25, 2005
Guests: Ramesh Mandava, Manveen Kaur, Vishal Mahajan, Neeraj Bajaj, and Venu Gopal
Moderator: Edward Ort (MDR-EdO)

This is a moderated forum.

MDR-EdO: Welcome to today's chat on the Java Web Services Developer Pack (Java WSDP) 1.5. Our guests today are five key members of the Java WSDP 1.5 engineering team: Ramesh Mandava, Manveen Kaur, Vishal Mahajan, Neeraj Bajaj, and Venu Gopal. Ramesh is the Technical Lead, Manveen and Vishal are responsible for the XML web services Security feature in Java WSDP 1.5, and Venu and Neeraj are responsible for the Sun Java Streaming XML (StAX) Parser. They're ready to answer your questions about Java WSDP 1.5. So let's start with a level-set. Ramesh, Manveen, Vishal, Neeraj, and Venu, can you give us a brief summary of what's new and significant in the Java WSDP 1.5 package?

Neeraj Bajaj: Java WSDP 1.5 for the first time has an Early Access release of a Sun StAX (JSR 173) implementation called Sun Java Streaming XML Parser (SJSXP)

Ramesh Mandava: Java WSDP 1.5 contains the new Sun Java XML Streaming Parser, an implementation of the Streaming API for XML, an FCS version of XML, and web services security, apart from bug fixes in other web services technologies. As you may be aware, Java WSDP 1.5 also supports 3 containers.

Manveen Kaur: Hi everybody! There are a lot of exciting web services security features in Java WSDP 1.5. This release includes support for securing JAX-RPC applications, security operations can now be configured either at the level of a WSDL service, port, or operation. The release also includes WSS interop scenarios and samples that make use of the enhanced configuration schema, along with ease of use command line tools specific to xwss, including pkcs12import and keyexport.

Venu Gopal: SJSXP is based on the xerces2 codebase and is a non-validating parser. It is XML1.0 and namespace 1.0 compliant.

Webster: What's the roadmap for the StAX parser? When will a release-level version be available?

Neeraj Bajaj: This is planned for sometime in March.

Neeraj Bajaj: SJSXP details can be found here. StAX brings an entirely new way of parsing XML, in pull style, giving more control to the application.

Vishal Mahajan: In addition to what Manveen has mentioned, this (FCS) release of xws-security allows a service (or a message receiver) to declaratively specify that it requires the incoming messages to be signed or encrypted.

Tom: Hello, I'm particularly interested in the development of applications using web services. What does Java WSDP offer to developers of applications using web services? Are there any tools simplifying this work?

Ramesh Mandava: Java WSDP contains all the technologies needed for implementing web services. You can use JAX-RPC for developing web services endpoints and web services clients to talk to any SOAP-based web services. JAXP provides XML parsing and transformation capability. SAAJ is the API used by JAX-RPC for constructing SOAP messages. XWS-Security would provide functionality to secure JAX-RPC applications. SJSXP provides pull parser functionality XML processing. You can get more details about the technologies in Java WSDP here. Also, NetBeans 4.1 is providing tool support for many of the Java WSDP technologies for developing web services.

Webster: Are there any performance improvements in this package?

Neeraj Bajaj: Java WSDP 1.5 has a StAX implementation, the Sun Java Streaming XML Parser. Our internal results shows that this is significantly faster than the SAX implementation that is part of JAXP

Webster: Is the XWS security implementation interoperable with other vendors' (for example, Microsoft) implementations?

Manveen Kaur: The XWSS implementation shipped as part of Java WSDP 1.5 is fully interoperable with other vendors. We have successfully participated in interop events for web services security (WSS) hosted by OASIS.

Webster: What's the schedule for incorporating the new technologies in Java WSDP 1.5 into J2EE?

Ramesh Mandava: Actually, some of Java WSDP 1.5 technologies are already part of J2EE 1.4, like JAX-RPC, SAAJ, and JAXP. In addition, the specific versions of the implementations in Java WSDP 1.5 are part of Sun Java System AppServer 8.1. SJSAS 8.1 also contains a JAXB implementation, as JAXB is used by JAXR. JAXB is not part of the J2EE 1.4 platform though. But JAXR is part of J2EE 1.4 platform.

Jerry: Does the StAX parser implement both the cursor and event writer APIs of StAX?

Venu Gopal: Yes SJSXP has implementations for both the Cursor and Event Writer APIs of STAX. In addition, you could also take a look at the Writer samples provide with SJSXP.

Webster: What are the performance considerations regarding pull versus push parsers? In what situations will a StAX parser be faster than a SAX parser?

Neeraj Bajaj: The StAX cursor API (XMLStreamReader) is a very efficient way to parse XML. StAX and SAX both parse XML in a streaming fashion in a very efficient way and consume much less memory. StAX is better than SAX in many ways, as these APIs provide more control over the data that needs to be read. StAX provides the natural advantage of skipping data that is not desirable, in SAX all data is pushed. Using StAX, one can parse multiple documents at the same time because the application drives the parsing and has full control over the parser. One needs to do nothing to stop parsing when using StAX, by comparison, SAX throws an exception to stop the parsing which is a costly affair. StAX allows the implementation to compute the values lazily, but with SAX, data needs to be computed before it is pushed to the application. A SJSXP performance comparison report against different parsers can be seen here.

ordinateur: An annoyance I have with the Xerces parser built into JDK 1.5 is that its error message for -DentityExpansionLimit='set too low' is more obfuscated than the adequately clear message in JDK 1.4. Any suggestions to remedy this? Would replacing or upgrading the xerces.jar with one from Apache cause problems?

Neeraj Bajaj: It is set to 10,000. It can be changed via the command line: java -DentityExpansionLimit=500,000.

ordinateur: You misunderstood the question. The Xerces parser bundled with JDK 1.5 gives cryptic error messages, which lead you down the wrong debugging path. I'm trying to mitigate this.

Neeraj Bajaj: I can look into this offline. Can you post this question to the Java & XML forum?

Webster: How (or where) do I get the Java WSDP 1.5 plug-in?

Manveen Kaur: The Java WSDP 1.5 plugin is not available yet. It will be available through Sun's products, such as Sun Java Systems Application Server and Web Server.

Tom: Assume I have developed a web service and registered in UDDI. What actions would you recommend I take in order to target the developer community (potential users of my service, facilitating the development of applications using my service)? Perhaps my question is too broad, but I would be very interested in hearing your opinion.

Ramesh Mandava: If your service is published into the public UDDI registry, then anybody in the world can potentially discover and can bind/use the service (at least in theory :) ). One thing you can do is to publish the service description including the URL where it can be accessed in WSDL. But right now, most of the registry (UDDI & ebXML) usage is in the intranet environment, because some of the web services related technologies are not yet mature.

ordinateur: I'd like to refer customers to recommended interoperable products, or at least steer them away from known problems. For example, I've found that passing arrays of complex structures are poorly interoperable. Where can I find comparisons of web standards conformance quality, and what to avoid?

Manveen Kaur: WS-I Web-Services Interoperability organization's (ws-i.org) Basic Profile attempts to enhance interoperability between different vendors. It has come up with a set of requirements. You can get the latest version of BP1.0 and 1.1 from ws-i.org. Java WSDP 1.5 includes a BP-compliant implementation of JAX-RPC, and a sample app, which have been tested for interoperability and serve as guidelines.

HankRatz: Can you recommend a good read/explanation of designing, what I think are called 'document based' services? Let me use an example because I don't know if I have the right terms. For example, Axis web services return every element in their own namespace, everything is a multiRef, even if they are different internally. I want my service to deliver/accept a document in the proper namespace that is and can be validated against its schema file. I want to design web services that support very hierarchical documents that are aggregates of many schemas. For example, a service that accepts an xpath statement and returns a document fragment. Thank you.

Ramesh Mandava: Doc literal based services are becoming more and more important. Starting with Java WSDP 1.4, you can use the JAX-RPC implementation to do doc-literal based SOAP messaging. JAXM was supposed to solve the document-based messaging problems which you were referring to. But JAXM didn't get much support. Now JAX-RPC is getting expanded to support document based messages. But as a user you would be still responsible for putting some application logic to do the aggregation and validation against different schema. We can provide more info to you regarding this later.

Webster: Where can I find a good tutorial on using the StAX API? I don't see anything about it in the Java web services tutorial on java.sun.com.

Neeraj Bajaj: There isn't any tutorial yet. But there is going to be a presentation on StAX very soon at JavaOneOnline which explains about using StAX and also compares StAX with SAX. SJSXP also has samples showing the usage of different APIs as part of distribution. I would also like to mention that there is a StAX-utils project on java.net which provides a set of utility classes that make it easy for developers to integrate StAX into their existing XML processing applications. The list of utilities can be found here

Webster: Will java.net projects be opened for JAX* technologies in addition to JAXB and JAX-RPC?

Manveen Kaur: JAXP 1.3 is already on java.net and so are fast web services and Fast Infoset.

Webster: What's the status of JSR 106, XML Digital Encryption APIs? When do you foresee this being incorporated into Java WSDP?

Venu Gopal: JSR 106 should be out for community review soon. We have plans to support JSR 106 in Java WSDP some time after the JSR 106 Spec is public.

Tom: Assume that I'm a developer of an application using a web service. What would be the most convenient and effective way for me to start using a web service? Would using Java WSDP and the wsdl-files suffice? I know there are loads of books on this, but I'm striving for your personal opinions on best practice? Again, maybe off topic, but your answer is greatly appreciated :-D

Ramesh Mandava: First, I would take the liberty of recommending the following two books for learning more about web services:

• Designing Web Services with the J2EE 1.4 Platform : JAX-RPC, SOAP, and XML Technologies
• J2EE Platform Web Services published by Sun Microsystems press.

Webster: Are there any other StAX or JSR 173 implementations?

Neeraj Bajaj: Yes. The StAX-utils page mentions all the StAX implementations available to date. The latest NetBeans release 4.1 EA has really good support for Web Services.

HankRatz: About distributed processing. Do you have any publications that describe possible architectures for distributing web services? I am only familiar with "hardware" proxies that round-robin one public host to several internal. I understand EJBs, but I am not sure if that is the best solution because I think most of the processing has already happened by the time the service call is evaluated. Thanks.

Manveen Kaur: Sun's Blueprints program effort works on providing guidelines for designing enterprise applications. There is also the book Designing Enterprise Applications with the J2EE Platform (2nd edition) that you can refer to.

ordinateur: Are there any plans to integrate annotations into web services? I believe that Apache Maven/XDoclet was starting in that direction.

Ramesh Mandava: The 2.0 versions of JAX-RPC and JAXB are going to be using annotations heavily. This will improve ease of development. Also there are a couple of new JSRs (JSR 250: Common annotations for the Java Platform & JSR 181: Web Services Metadata for Java Platform) that will be taking advantage of annotations and metadata. The J2EE 5.0 platform may contain these technologies and the implementations would be available in future Sun products also.

ordinateur: Any practices that you would recommend as being deprecated?

Venu Gopal: Any specific area you are looking for?

Vijay: When will Java WSDP be JAXB 2.0 compliant?

Ramesh Mandava: JAXB 2.0 will be part of Java WSDP 2.0. Also, the EA implementation of JAXB 2.0 will be available at java.net in next couple of months before becoming part of Java WSDP 2.0.

ordinateur: Does Microsoft's 'dot net remoting' offer sufficient openness or interest for Sun or Java 3rd parties to pursue interoperability?

Manveen Kaur: There have been successful attempts at interoperability between Microsoft's WSE 2.0 and Sun's Java WSDP 1.5.

jerry: Does SJSXP support DTD?

Venu Gopal: Yes it supports DTD but it does not support DTD validation. SJSXP is a non validating XML 1.0 and Namespace 1.0-complaint processor. If DTD is present and appropriate properties are set on XMLInputfactory, then default attribute values are reported if not specified in the instance document. If entity references are present, then based on the properties set, they are either resolved and reported as character events or entity reference events.

Webster: I'm not sure I understand what determines which web services technologies (or even what level of these technologies) get incorporated into a particular release of the Java WSDP. What criteria do you use in making those decisions?

Ramesh Mandava: We would apply the following criteria before making a technology part of Java WSDP:

1. We would go though the available WS* standards and see if any of those WS* standards are important for users
2. We need to have a way for the technology to be part of a Sun product, that is, we don't include any evaluation technologies as part of Java WSDP. Once users adopt the technologies that are part of Java WSDP, they can be sure that they will get support in some product
3. Of course, resource constraints would play a role.

Vijay: Is it possible to have a common jaxb.properties and bgm.ser for multiple jaxb contexts? Right now there are multiple instances of them spread into multiple packages and it is difficult to manage.

Manveen Kaur: No. But in the upcoming JAXB RI 2.0, we won't have any of those files.

Vijay: That would be very cool!

Vijay: To what extent does the -extension switch support JAXB2.0 features?

Manveen Kaur: It covers features that are also covered by JAXB 2.0, but they are not directly related to each other. The input we received from the users who tried the -extension switch was used as the input for JAXB 2.0.

MDR-EdO: Well we've quickly come to the end of our session. I want to thank everyone who participated today. I thought we had a very nice range of questions. And of course, I'd like to thank our guests for their answers.

Venu Gopal: Thanks all. It was nice chatting. If you have any questions regarding SJSXP or JAXP please mail them to us at users@jwsdp.dev.java.net.

Manveen Kaur: Thanks everybody for some great questions!

Neeraj Bajaj: Thanks Everyone. I would also like everyone to check out the JAXP 1.3 RI Project on java.net. JAXP 1.3 has some cool new features like the new Schema Validation Framework which can improve the performance of Schema validation multifold times. There are new XPath 1.0 APIs and new datatypes which map to XML Schema datatypes, thus bringing richer XML schema support directly into the Java platform. Goodbye, nice talking to you.

Ramesh Mandava: Thank you for all the good questions. If you need more information about Java WSDP technologies, then please visit the Java Technology and Web Services page, and we invite you to participate in Java WSDP community at java.net. Also please send your feedback messages to users@jwsdp.dev.java.net, users@jax-rpc.dev.java.net, and users@jaxb.dev.java.net.

MDR-EdO: Moderator signing off. The forum is now unmoderated.