WSDL

WSDL
Web Service Description Language (WSDL) is an XML document standard defined to describe a SOAP web service. Specifically, a WSDL defines the message, portType, binding and services of a Web Service. The message is basically the XML schema of the SOAP envelope contents, including message structure and the data types used in the message. The portType describes groups of operations (methods) including input and output messages (parameters). The binding describes the specifics of a portType, including style and soapAction. Finally, the service section describes the location of the Web Service, which is often a URL.

WSDLs are consumed by programs which create proxy classes such as wsdltojava from Apache Axis, which generates Java, or wsdl.exe in .NET, which generates VB, C#, or JS. WSDLs are also consumed by Web Service messaging products such as XML Spy Pro and Microsoft InfoPath.

WSDLs are created from classes by javatowsdl or directly by Web Service servers. IIS automatically produces a WSDL for a .NET Web Service. Axis will produce a WSDL from a jws file, which I will discuss next week.

What this means to the enterprise
Simply wrapping a legacy application in a Web Service is very powerfull. This allows Web Service enabled application, such as Microsoft Office, to talk to the Applications (more easily). The preliminary schema validation of the message occurred client side, with no additional programming. This validation, combined with the definition of a specific message description in the WSDL, including readable legacy field names with some meaning, enabled a user, to build an application that consumed this web service.

References

• http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnwebsrv/html/understandwsdl.asp
• http://radio.weblogs.com/0101679/stories/2002/02/15/aBusyDevelopersGuideToWsdl11.html
• http://ws.apache.org/axis/java/integration-guide.html

UDDI

UDDI
Universal Discovery Description and Integration (UDDI) is a protocol standard for Web Services repository. Specifically UDDI allows for storage and searching of web service WSDL files and associated information, like web service descriptions, provider information, and categories. Currently UDDI V3 is in beta implementation at the IBM, Microsoft, and SAP sites listed below. You can register and search for Web Services at these sites. The standard describes Web Services for publishing and searching for Web Services.

Support
Microsoft provides UDDI support in Visual Studio and Office for locating and consuming web services, addition to an SDK to publish and search. Also, UDDI services are delivered with Windows 2003 Server.

Also, there is a java UDDI server available on sourceforge and there are java APIs for accessing UDDI, including uddi4j and JAXR. However, using the Web Services described at the sites below is most likely a preferred method to search a UDDI registry.

UBR
Universal Business Registry (UBR) is a specific implementation of the UDDI V2 standard for search for businesses and business web services.

What this means to the enterprise
When an enterprise supports SOAP Web Services for data access, form definitions, and db actions, these Web Services could be published in a local directory at a clients sight. A design tool could search UDDI like the way it searches for web pages today through a search engine. These local UDDI searches could be combined with searches to multiple local servers and Internet based UDDI servers. Since Web Services are the end result of any UDDI search, this would be most appropriate for a developer in a forms designer scenario.

References

• http://www.uddi.org/
• http://uddi.microsoft.com/
• http://uddi.ibm.com/
• http://uddi.sap.com/
• http://soapuddi.sourceforge.net/

SQLXML

SQL XML
SQLXML is a really interesting feature of Microsoft SQL Server 2000. It allows you to send SQL statements or XML queries to the server and get XML back. For instance you can send a SELECT statement to get back a list of currency codes. This would be very useful in an SEA style web applications. It also has support for SOAP Web Services, XPath queries, and SQL templates for other operations, like UPDATE and INSERT.

Since SQLXML is accepting SQL and making the database queries through native drivers, it should perform and scale significantly better than DME.

Authentication and Security
Authentication is managed by IIS virtual directory permissions. Since this utility is native to SQL Server database, security would be limited to the table and column security managed directly by the database. Lawson currently has a utility to dump SQL statements from LAUA data, bldibmsec for db2, to a script file. This script is executed on the database and applies grant/revoke privileges to table and column entities. This native database security is used to secure direct database access with ODBC, OleDB etc and would apply to SQLXML access.

What this means to the enterprise
I believe that it would be possible use to SQLXML to access enterprise Database Information. This would provide direct URL based XML data access without the need to go through a custom DB layer. The drawbacks include lack of support for metadata and custom security. Also, Oracle and DB2 support for an SQLXML standard is not clear. Giving SQL database access to application developers provides more flexibility and also opens the door for problems like database tuning, index design, and SQL syntax issues between db vendors.

More Information
http://www.sqlxml.org/
http://msdn.microsoft.com/library/default.asp?url=/nhp/Default.asp?contentid=28001300