Wednesday, January 14, 2004

Features of a Service Oriented Language

Service Oriented, Protocol Connected, Message Based
Here are some casual thoughts on what I would like to see in a service oriented language. This is my first attempt at this... I'm sure I'll get some feedback ;-) and will update it.

- The service is a first order concept, both sending and receiving
- Support for the strong interface (think WSDL)
- Mandatory support for Long Running Transactions
- Faults and Compensation are first order
- Protocols for transport and fulfillment of NFR are intentionally left out of scope

- Message is a first order concept
- Message is defined using a platform independent markup
- Support for message correlation properties; helpers for distributed state mgmt.
- Universal addressing scheme (assumes router)

Types / Vars
- Typing & vars are consistent with message system
- Remote variables (think REST)

Functional Containment
- The 'service' is a container (and managed)
- The 'object' continues to live. Objects are contained in services.

Invocation and Service Hosting
- WSDL's can be imported directly into the runtime. Operations and messages become first order citizens.
- Access & manipulation of binding / listener is first class.
- Language assumes that all systems are peer (both client and server)

Schema Manipulation
- DDL: Import / export / create / modify (consistent with type system)

Data Manipulation
- DML: transform (consistent with type system)

Flow Control
- Usual branching & looping
- Parallel execution; parallel joins (first order)
- Forced sequential processing

Event Based
- Events are a first order concept
- Time & activity based events

Metadata Ready
- Declarative metadata becomes a first order item (see jdk1.5)
- Service oriented loading / unloading of metadata / models / gen’d code at runtime
- Reflective knowledge of declarative non-functional polices (think ws-policy access)

Base Service & Extensions
- Concept of an extendable base service
- Service may have multiple interfaces
- Aspects may easily be applied to service
- Language is extended via ‘more services’ not ‘more syntax’

Service Network Awareness
- Service is aware of the network that it lives in (topology, routers, etc.)
- Service is aware of service-enabled remedies to non functional requirements (Virtualization, etc.)
- Service has the ability to modify the service network at runtime

OK. So a good question is, "which of these are part of the 'language', which are 'service libraries' or other?" I'm in favor of the *least* amount of required syntax possible. But, I like the idea of having *mandatory* service library extensions.

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