RE: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"

One could call it maturity model just as an OSI stack show maturity of the network infrastructure with the simplest being a single layer 2 subnet. However, as Joe pointed out, it is meant more to promote interoperability. The idea is to allow for

Each layer of SOA can develop and scale independently.

For example, you could have a very large Layer-1 SOA Fabric (or ESB or Information space) that could scale within and outside the enterprise. Layer-2 can adopt the domains (namespaces) to partition this information space.

The interfaces as one traverse vertically across layers are independent of interfaces that one uses to communicate across horizontally.

For example Layer 1 to Layer 2 is independent of Layer 1 to Layer 1 of different SOA nodes. Further Layer 1’s data is Layer 2’s payload i.e. metadata of higher layers applies to data of lower layers. This means that the data model does not need to be communicated vertically across layers but only horizontally across nodes.

Programming model only needs to be defined for the highest layer not every layer in SOA. This is critical if we want scalability

The process layer is the new platform for application development. All other layers become part of the infrastructure and should get supporting diagnostic and test suites not IDEs.

Interoperability testing is simplified significantly. Customers can mandate that all Layer 1 equipment be interoperable instead of saying Vendor A’s SOA should be interoperable with Vendor’s B which is almost impossible to test.

For example, Layer 1 interoperability can be boiled down to testing if a message can get from one transport endpoint to another across multiple vendor’s Layer 1 infrastructure. Kind of like the way we test extreme L2 switch with Cisco L2 switch.

Vikas

From: Christopher Bashioum [mailto:cbashioum@mitre.org]
Sent: Monday, May 23, 2005 12:06 PM
To: soa-rm@lists.oasis-open.org
Subject: RE: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"

I like it too, but i think it is more of an SOA maturity model than a RM. Each layer is a higher level of SOA maturity, with initial SOA beginning in layer 2 (I think)

From: Chiusano Joseph [mailto:chiusano_joseph@bah.com]
Sent: Monday, May 23, 2005 1:42 PM
To: soa-rm@lists.oasis-open.org
Subject: RE: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"

Wow that's a very interesting way of looking at this. So starting with Layer 1, the RM would add the concept of a service, and discovery of service endpoints, to traverse to Layer 2. Similarly, to traverse from Layer 2 to Layer 3 the RM would add the concept of a session, then for Level 4 the notion of a choreography or orchestration.

I like the sound of that - it seems very valueable for interoperability.

Joe

Joseph Chiusano

Booz Allen Hamilton

Visit us online@ http://www.boozallen.com

From: Vikas Deolaliker [mailto:vikas@sonoasystems.com]
Sent: Monday, May 23, 2005 1:32 PM
To: Chiusano Joseph; soa-rm@lists.oasis-open.org
Subject: RE: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"

One could potentially map the SOA levels discussed in this blog to layers in a SOA-RM.

Layer 1: Messaging/Queing with routing and transformation of messages. The endpoints for this layer are transport endpoints.

Layer 2: Mediation Layer or Brokering Layer. The endpoints to this layer are the service endpoints. Endpoints are discovered using a discovery protocol (like DNS).

Layer 3: Session Layer. The endpoints to this are session endpoints. Session endpoints can be all on one service endpoint or multiple.

Layer 4: Process Layer. This is the choreography/orchestration layer at which new services can be developed.

The RM then would need to define the notion of protocol data unit that traverses up/down and in between two of these stacks. (analogous to OSI).

Thanks

Vikas

From: Chiusano Joseph [mailto:chiusano_joseph@bah.com]
Sent: Monday, May 23, 2005 4:19 AM
To: soa-rm@lists.oasis-open.org
Subject: [soa-rm] David Linthicum Says: "ESB versus Fabric.Stop It!"

Forwarding a very interesting and pertinent piece[1] from David Linthicum's (CTO of Grand Central) blog, titled "ESB versus Fabric…Stop It!". David also discusses 6 different "levels" of SOA, ranging from simple single point-to-point SOAP messages (Level 0) to SOA that incorporates orchestration (Level 5).

Joe

[1] http://www.webservices.org/index.php/ws/content/view/full/63539

Joseph Chiusano

Booz Allen Hamilton

Visit us online@ http://www.boozallen.com

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