Recently I have done POC for measuring perofrmence of various java web service frameworks axis2, jaxws, apache cxf with their supported XML data binding framework. I used top-down approach for web service development. After doing load test using SOAP UI (burst test, 600 seconds, 20 thread) I found Apache Axis2 + JiBX out performs other web service stacks, I also had custom implementation of processing message payload by using XPath and Stax. As per load test results I can rank them as axis2+jibx, axis2+abd+stax, axis2+xmlbeans, jaxws + jaxb, axis2 + adb, axis2+adb+XPath.
I recommend JiBX and Stax for performance reason, where JiBX is the XML binding framework and Stax is PULL parser. JiBX manipulates the byte code to weave its XML binding at compile time and most of the other frameworks are using JAVA reflection at runtime - makes them slow.
If you are writing or reading XML using java parser then go for Stax (part of JDK 6.. for other JDK download the Stax distribution). If you are looking for performance with XML binding framework then go for JiBX.
See the XML schema support before going for any of these XML data binding frameworks and also check your XML Schema design.
In this blog I am going explain how to design, create and deploy JAXWS based web service. I am going to create a simple User Management web service which would have create, select, update and delete for User. you can find the source code for this blog in my google code repositoty. Soon I will provide source code location.
I would be using JAVA 6, Eclipse - Galileo JEE (with Maven plugin & Embed Jetty plugin) & Fedora 11 OS for development and soapui for testing.
JAXWS is the XML based web service release over the traditional RPC based JAX-RPC web service model. JAXWS only supports JAXB as a data binding framework. JAXWS has been released officially with JDK 1.6. You can also download its reference implementation from java.net
There are two methods for web service development top-down and bottom-up.
top-down
In this approch we have to design WSDL and XML Schema first and using Java Web Service framework provided tool generate server side service classes. So in short we would call it as "WSDL first approach". With this approach you can use any web service framework since it is driven by WSDL and XSD. Using these two inputs you can generate server artifacts easily.
bottom-up
In this approach we have to write code first and using framework provided tool generate the WSDL and data binding XML code. In short we would call it "Code first approach". In the bottom-up approach web service design is tightly coupled with the web service framework, since we are writing code first and then generating server artifacts from it.
Service Oriented Architecture (SOA), an architecture which has one or more services defined and exposed by service provider to the service consumer. There are various forms in which you can expose a service to consumer. In JAVA world it can be web service, HTTP remoting, messaging, EJB, RMI etc.; if we see all these are various technologies, API or frameworks using which one can expose its core service to outer world.
Now when we think of service then it must cover other aspects which makes it a complete service like transaction, security, portability, interoperability, scalability and maintainability. Ideally it can be the POJO later on which can be exposed as service using java web service, remoting, rmi, EJB or messaging.
SAO is not just a web services many people think SOA means just a web service. When we thinking about writing a services; to fit it in SAO it must follow certain design principals and patterns soapatterns.
In general it is a messaging between two components, communication using request and response. Request and response defines a contract between provider and consumer of the service. To accomplish particular business function which has been wrapped in service, in nature it required certain type of input to produce expected type of output to fulfill certain business requirement. I am sure you must have come across terms like stub-skeleton, marshalling-un-marshalling these are the general terms we used while defining request and response for inter communication of components.
Request & response carries message payload no matter where the consumer resides; means a consumer either locally sitting in same runtime environment or different. Let’s say I have exposed a service using EJB in this case I have an option to consume it locally or remotely and the message payload over the network would be binary. Point I want to make here to process request and response you need JAVA on either end. So our exposed service can only be consumed by JAVA consumer – this is limiting our service interoperability and again the format of request and response not based on open standards. Other than JAVA no else can crack it. So we need to design request and response in such a way it must be transparent to the request and response processors. Answer to this is XML – this has been widely accepted. A well formed document which can easily wire over the network and processed using available XML parser.
We can define a XSD which acts as a blue print for the request & response XML. XSD defines elements, attributes, child elements, order of child elements, types of elements & attributes, default and fixed value for the element & attribute and many more. You can find more about XSD.
There are many ways to process the request & response XML message payload. We can use Java XML API like DOM, SAX, Stax, XSLT and also XPATH to parse and create a XML.
DOM
Memory foot prints depends on size of XML it dealing with, loads XML fully in memory, it can traverse in any direction and it can parse and create XML document.
SAX
Event based push parser. It sends an event out for XML entity. It has low memory foot prints compare to DOM, It can only traverse forward only direction. It can only parse XML and cannot crate document.
StAX
Event based pull parser. It has very low memory foot prints compare to DOM & SAX parsers. It sends an event out for XML entity but on demand. It can only traverse forward only direction and it can parse and create XML document.
XPath
This requires XML document loaded in memory. We can create XPpath expressions to retrieve value from the XML.
XSLT
It requires XSL and XML which produces desire output - XML is the one of the output format.
All above requires manual hand written code for parsing and creating XML. Alternative for this is XML data binding framework which gives you generated JAVA classes using which you can create and parse the XML document easily. Apache XMLBeans, JAXB, JiBX are some of them. Create the XSD and pass it to framework it will generate JAVA classes for you to deals with. No need to know any parser API. Use setter and getter to create and parse XML.
Apache XMLBeans
Apache XMLBean is the open source project. It claims 100% schema compatibility. It prefers array for collections and enumeration of value for the XSD choice.
JAXB
Comes with JDK, Prefers List for collection unlike apache XMLBean array. No enumarion support for XSD choice.
JiBX
Is the open source XML data binding framework. Performance wise JiBX out performs XMLBean & JAXB. Generating bindings out of it is little bit tedious job, but once done it gives you its real value. It weaves its biding code at the time of binding generation and not run time by using JAVA reflection.
Satx out performs other JAVA XML pareses and JiBX ranked number one in XML data binding frameworks. But before going for any of these parsers or XML data binding framework - “review the XML & XSD design and data binding framework schema compatibility”.
