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The cell phone companies have not been standing by watching this trend emerge; they have begun to lead the way. At JavaOne, Nokia announced that they are building a service-oriented architecture framework on smart mobile phones that could make Web services more of household word since they will be running on our phones.
This is a bit different than more traditional SOAP interfaces between desktop/server applications and telecomm hosted servers, such as MMS message servers, location servers (see below), and presence servers. We know those approaches work, but the core shift here is a move from simple information sharing to full blown deliver of application services/behavior down to mobile devices. Thus, this is not only new, but useful. Nokia is proposing the integration of mobile clients directly into SOAs using asynchronous Web services.
Truth-be-told, mixing Web services with mobile devices is not a new concept. For instance, the .Net Compact Framework has been supporting Web services for a while now. On the Java side of things, kSOAP is a J2ME based SOAP parser and the JSR 172 provides a standards set of XML and SOAP APIs on J2ME devices.
The issue with the existing approaches is the assumption that the device interacts with one service at a time, using synchronous mechanisms (much like traditional RPCs). As you may know, synchronous and mobile devices are not terms that go well together, so many developers opted for more customized types of approaches rather than leveraging these standards.
Web services, in the context of mobile computing, is all about the notion of devices that can move in and out of service areas, and at the same time find and leverage Web services as needed, and with the right validation. This should be a bidirectional mechanism where mobile devices can both consume and provide services; in essence the mobile device becomes a peer.
There never is just one standard, is there? In the mobile Web services world you also have to consider the Open Mobile Alliance (OMA) and their OMA Web services 1.0 specification. On June 15 the OMA announced the public availability of new and "up-leveled" mobile specifications which are built by OMA member companies, defining how wireless data services may be shared across operators, terminals and geographies. There are 350 member companies in the OMA.
This standard, like the Nokia announcement, defines how Web services may be exposed, discovered, and consumed using standard Web services technologies. The OMA Mobile Locations Protocol defines a core set of operations that the location server is able to perform, and the OMA Online Certificate Status Protocol defines a protocol for trusted certificate validation.
The goal of this specification is to provide guidelines for Web services implementations within the OMA architecture, and how to leverage SOA in the world of mobile devices. Moreover, the specification ensures interoperability across servers and terminals supporting Web services protocols.
Moreover, this specification defines security threats and services, privacy and identity management, messaging and transaction, as well as policy and system management. Also, it defines the ability to deploy OMA Web services such that the processing associated with common, cross-enabler capabilities may be factored out of individual Service Enablers and delegated to other entities. Finally, the specification defines the ability to automate the discovery and use of policy information that governs Web services interactions.
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