BizTalk is well suited as middleware. Where you wish to translate an input file into an output file and send it to some endpoint. In our case, we used it to convert and send files to SAP. In many ways, it very flexible, and you can do almost anything you want with it. In many ways, it's a better solution than your SAP XI or PI as middleware, since it's much less expensive, and allows you do interface with non-SAP systems.
JBoss EAP is subscription based/open source platform. It's very reliable and great for deploying high transaction Java based enterprise applications. It integrates well with third party components like mod_cluster and supports popular Java EE web-based frameworks such as Spring, Angular JS, jQuery Mobile, and Google Web Toolkit.
It is very user friendly. Users can change rules during run time and change workflow.
Huge capacity for queueing messages. It supports all types of adapters like Oracle, Salesforce, SMTP, FTP, etc. Also users can built custom adaptors.
If users want to dynamically deploy their solution without any downtime, this is a perfect solution. BizTalk will be a good fit, especially for public-facing websites.
Well-proven in the market. I used it when developing a website for Virgin Trains, catering more than 800K user requests per day.
MOD_CLUSTER integration. JBoss EAP integrates pretty well with mod_cluster. This is an intelligent load balancer especially useful in highly clustered environments.
Supports enterprise-grade features such as high availability clustering, distributed caching, messaging etc.
Supports deployment in on-premise, virtual and hybrid cloud environments.
JBoss EAP is lightweight and doesn't really consumes much physical resources. It's high performing and suites well for high transaction Java enterprise applications. The out of box performance settings are not really great and you will have to configure the settings to suite your environment to leverage it's full benefits.
BizTalk Server has been supported for more than 15 years. It is well proven in the market. Microsoft has provided excellent support with technical issues.
BizTalk was selected here mainly because it is easy to integrate to a .NET application (most of them are Web Service, WCF SOAP, WCF REST and Web API) and many backend databases are Microsoft SQL Server. Another benefit is that the monitoring job is easy to set up and centralize with other .NET application monitoring jobs.
A positive impact has been the quicker turnaround time of a part request and that part showing up in SAP using Biztalk as middleware.
A somewhat negative impact has been the somewhat insufficient error logging/message capture settings that Biztalk provide. This has caused occasional delays when attempted to create parts for the business.
A somewhat negative impact has been the need to have a specialized developer who understands Biztalk to troubleshoot issues with the Biztalk and SAP interaction when creating parts, and when adding new fields to the parts.
Jboss EAP is easy to deploy and configure. This lead to lower cost and faster delivery.
Even though we have large number of machines running JBoss, we have only two Jboss Administrators. It doesn't requires too much administration and maintenance on daily basis and reduces number of administrators required for large implementations.