The next generation enterprise applications are being built using SOA (Service Oriented Architecture). This is partly driven by requirements such as supporting multiple operating systems, multiple data bases, multiple programming languages and even SAAS applications.

VisualSchema.com provided the ability to visualize XML Schemas. Now, a new website, VisualWebservice.com provides the ability to visualize web service documents (WSDL files). Unlike VisualSchema which only shows a pre generated visual schemas, Visual Web Service allows the ability to provide a WSDL url or upload a WSDL file and interactively obtain the Visual representation of the WSDL.

When working with XML and XML Schemas, Namespaces makes it a bit difficult. The main issue with Namespaces in my opinion is the difficulty in dealing with the prefix to the namespace uri mapping. The software used to generate Visual Schemas has been tested with several different standards (as can be seen from this blog history), yet, very rarely some issues are identified in the software. As part of generating the Visual Schemas for Election Markup Language (EML), two additional issues were uncovered. One was an issue where the name of the element instead of the qname was used and it’s a outright implementation bug. However, the other one was more interesting.

EML schemas include additional schemas (core and external) and these included schemas include a few more schemas that have their own namespaces. The current Visual Schema software implementation computed the namespace prefix to uri mapping based only on the outer most schema. So far, all the other standards worked with this approach (either because they didn’t have multiple namespaces or they included all their namespaces in the outer schema). However, this didn’t work with EML since additional namespaces were defined in the included files. This makes it a bit complicated to deal with because usually developers doesn’t care about explicitly loading the included documents and just rely on the XML Schema parsing API to do it for them. So, there are two approaches to deal this issue

1) Recursively navigate through the XML Schema DOM and get all the included schemas and gather the namespaces defined in them. Ofcourse, this has the issue of making sure that the relative paths are properly converted to absolute paths.
2) Implement a custom Input Resolver and on the fly as the XML Schema parser is fetching the included schemas, gather the namespaces.

I am yet to decide on the approach I want to take, mostly will go with the approach 2. However, to deal with EML, the included namespaces are hard-coded for EML schemas.

My recommendation for anyone creating XML Schemas is perhaps to redefine all the namespaces from the included schemas (recursively) in the outer schema. Otherwise, developers working with the schemas might face challenges depending on the sophistication of the tools they are using.

Right now I am watching Senator Barack Obama speaking in Minnesota on his successful winning of the required number of delegates for the nominations. Well, that has nothing to do with this post. But yes, the fact that this year the US Presidential Elections are going to happen has prompted me to look for XML Schema specifications related to Elections and found them on the oasis-open.org website.

VisualSchema.com is pleased to offer the Visual Schemas for Election Markup Language (EML) XML Schemas.

While creating the visual schemas for EML, a few issues were encountered. They will be listed in the next post.

HR-XML 3.0 is still a draft and continuously evolving. The last time Visual Schemas were created for HR-XML, there were 10 nouns. Now it has grown to 31. The latest Visual Schemas for HR-XML 3.0 Draft specifications are now available. The Visual Schemas are also regenerated with inline annotations to make it even more easy to study them. Annotating XML Schemas is like commenting code and good code is always accompanied with comments.

VisualSchema.com is pleased to announce the availability of Visual Schemas For Amazon Fulfillment Web Service (Amazon FWS). Amazon FWS allows merchants to outsource their order fulfillment process to Amazon by storing their inventory in Amazon’s Fulfillment centers. This allows merchants to focus on their website and online marketing. When an order is placed, using Amazon FWS, it’s possible to pick, pack and ship it from Amazon Fulfillment center all from the comfort of a mouse click (assuming you have the necessary software that allows you to review the customer order, verify the payment details and then interact with the Amazon FWS to initiate the order fulfillment).

The Amazon Associate Web Serivces Visual Schema has been updated to reflect the latest version of the Amazon Associate Web Services. The key change is the inclusion of the RelatedItems element to the Item definition.

Maintaining any good website requires some resources and that requires some money. Visual Schema chose to depend less on advertising revenue so that the website is less cluttered. As a result, an affiliate store has been added to Visual Schema, called Visual Store. This store is created using Amazon Associates Web Services (A2S or formerly known as Amazon ECS).

Just like well commented code makes it easy to understand, XML Schemas can be augmented with comments as well. This is done using the documentation element within the annotation element. Annotation element can be part of many of the XML Schema constructs.

Visual Schema provided a way to visualize the XML Schema definitions. Now, Visual Schemas can display the annotations as inline tooltips so that the schemas can be studied along with their comments. opentravel visual schemas are the first to get this functionality on our website.

Recently we announced Update to opentravel 2007b. Based on a review of the corresponding visual schemas by the opentravel team, an issue has been identified. This has been fixed and the visual schemas for opentravel schemas has been updated.

The issue identified is an interesting one. At issue is whether using NMTOKENS type as the base type for creating an enumerated restriction simpleType is correct or not. While the XML Schema specification does not explicitly prevent this, it certainly does not seem to be the right thing. Visual Schema code has been fixed to allow this type of schema definition.

VisualSchemas for opentravel have been updated to the latest version of opentravel, 2007B released in December 2007. The latest Visual XML Schemas for opentravel are now available.