The good news about WOA is you probably have many of the technologies and infrastructure components, and know enough about the standards and technologies to get a WOA up and running fairly quickly. If you are an enterprise architect, you may not like the approach or may want to combine it with SOA, big, complex EA and any number of other things, but try to keep an open mind and keep things simple.
To keep things simple, define a small set of standards and technologies that will be used in your WOA. To get started, you will need a basic set of standards/technologies. For example, a good starting point would be:
- JSON (and/or others)
Looking at the above list you have fundamental distributed service architecture capabilities:
- HTTP/HTTPS - provides messaging and methods
- URI - provides the resource identification (endpoint addressability)
- JSON - provides a simple data representation
- REST - provides the resource (instance, service) model
You'll also need to consider security. There are several options such as TLS (SSL), OAuth, OpenID, OpenLDAP, encryption, etc.; there are open source and commercial options...but essentially, you need authentication and authorization at a minimum, and you may want more such as accounting, auditing, encryption, etc.
The heart of a SOA is the Enterprise Service Bus (ESB). If you consider a SOA model, the ESB "sits in the middle" processing all (most/many...some subset if not all) message requests and responses; it may transform, parse, enrich, strip, burst, etc. processing the message. If you are using WSDL and the plethora of web standards that can be added to WSDL, you'll have a fairly large envelope to process which will take even more time. To process these messages (maintaining SLAs and QoS) would require significant infrastructure, that is scalable and fault tolerant and the end result is likely expensive. If you are using a commercial ESB...even more costs. Complexity and cost, what are the benefits, when will the benefits be realized?
The heart of a WOA is the web server. There are many options here, and you probably already have your own favorite set of web server technologies. That said, this may be a good time to have a look at more modern web servers (e.g., nginx). At the simplest level, a web server processes requests, ideally quickly and efficiently and can scale to a large number of users. In a WOA, requests can be processed locally (by / on the web server) or remotely, by another web tier that hosts/exposes REST endpoints. The REST service implementation is up to you, what it does and how it does it, is also up to you. That's really it.
In SOA, a collection of web services isn't sufficient as you need service infrastructure too. In a WOA, having a web server and REST services is about it. If you want SLA, QoS or other analytics, you can add those to your web server or your current infrastructure if you don't have them. SOA builds on the basic web infrastructure (adds more infrastructure); WOA is the basic web infrastructure. WOA is used by the Internet, it should meet your needs as well.