AppFabric and BizTalk

"BizTalk is Dead and Out", on overhearing such a statement I was intrigued to know who the slayer was when a new name surfaced "AppFabric". The ensuing discussion was deadlocked but generated a curiosity in me as to what was the fuss all about. Reading through articles from the BizTalk Gurus I summarize the following:

What is AppFabric?
The simplest way of visualizing AppFabric is that it is an extension of Windows Application Server capabilities supporting the developer in implementing most of the non-functional requirements. Application development is not about just writing code but has certain associated quality of service parameters like scalability, availability, performance etc. In some cases the applications are also required to be transactional with a certain degree of administrative capabilities. Traditionally developers have spent substantial efforts in implementing even one of the above parameters whilst or post application development. What we really need is something out of the box addressing or supporting such QoS requirements on the existing infrastructure.
Look no further as AppFabric provides all of the above and more. And the best part is that it is available on the windows server platform installed on most of the development machines.
Windows Server AppFabric is an extension of IIS (Internet Information Services), WAS (Windows Process Activation Service) and .NET Framework 4.0 providing enhanced hosting, caching and service management facilities.

Does AppFabric replace BizTalk?
Finally I cut back to the discussion which actually triggered off my curiosity. Does Windows Server AppFabric replace BizTalk Server, Microsoft’s widely used application integration tool? Instead of trying to answer the question directly, we shall compare both the products on certain parameters and then try to draw a conclusion. Any form of working experience on BizTalk server would be beneficial in understanding the below table:

Features	BizTalk Server	AppFabric
Server type	* BizTalk is an application integration Server * XLANG based workflow engine	* AppFabric is an extension to windows application server * WF based workflow engine
Purpose	Enterprise level integration mediating various transport and message formats across heterogeneous systems	Extend IIS/ WAS providing advanced hosting capabilities for WCF (+WWF ) services
Architecture	Messaging based system with support for services i.e. schema based system	Services oriented system i.e. uses code contracts
Persistence	* Supports Message Persistence and Instance Persistence with suspend/ resume functionality using SQL server * Use of SQL Server introduces higher latency but advantages of disk persistence	* Supports Instance Persistence with suspend/ resume functionality using SQL server or AppFabric in-memory caching services * Use of in-memory AppFabric caching ensures low latency and improved throughput at the cost of risking disk persistence
Rules Engine	* Business Rules Engine (BRE) providing support for dynamic complex business rules * Rules Composer provides a visual representation of the rules for Business Workers	* Very little support via WF Rules for simple business rules * No visibility to Business Workers as rules are modelled In C#
Adapters	Multiple third party adapters available out of the box supporting heterogeneous system integration	AppFabric Connect allows leveraging BTS adapters but does not have a out of box adapter collection
Publish/ Subscribe	* Workflow engine along with the Message Box provides a publish-subscribe model which auto manages multiple concurrent workflow threads for processing messages * BizTalk host provides auto throttling ensuring load balancing	* With the absence of a message box, AppFabric does not provide a publish-subscribe multi threaded model * However there are WF constructs available for parallel execution which has to be managed by the developer
Monitoring and Recoverability	* BizTalk Admin Hub Page provides an overall view of the system health * Health Activity Tracking (HAT) can be used for viewing and resuming suspended resumable instances	Dashboard provides a view to the overall health of services configured to utilize persistence and event collection
Tracking, Archiving and Purging	* Business Activity Monitoring (BAM) provides a rich set of tools for tracking message data and flow through the engine * Dedicated tracking host for moving tracking data to BAM * SQL Server Agent jobs can be configured for purging and archiving tracking data from time to time	* Provides a set of tools which allows selection of a tracking profile to configure message logging and tracing features * Windows Powershell cmdlets are provided for purging and archiving tracking data from time to time
License Cost	Yes, has to be bought independently from Microsoft	No, Currently free and is already licensed with windows server 2008, Windows 7 and Windows Vista (SP2)

What the comparison brings forth is that AppFabric is best suited for low latency, high performant application server services providing non-functional features of service level tracing, monitoring, distributed caching, hosting capabilities etc. out of the box. Such solution architects might have previously considered BizTalk as an option as most of the mentioned features are in-line with the tools and services it readily provides.
However Windows Server AppFabric still has to reach the comprehensive collection of tools and features that BizTalk provides as an integration server. As highlighted in the above table, BizTalk still has a very unique publish/ subscribe model, strong rules engine, a mix of third party adapters to name a few which are missing in AppFabric and which makes BizTalk server a strong integration tool. All these features at an extra license cost obviously means that solution architects will consider AppFabric as an option before recommending any technology to the client which would fulfill their requirements.
To summarize AppFabric instead of replacing BizTalk server complements it well, each leveraging the features of the other. Future developments in each of the areas will try to bring both the products closer making it seamless and easier to use and configure. As put by the Microsoft pundits “Biztalk vNext will transition to be AppFabric based”.

Would be more than happy to get any suggestions/ corrections/ feedback on the above post @ virus.vinay@gmail.com