Certain requirements may drive IS departments to add graphical user interface (GUI), workstation, local area network (LAN) and/or wide area network (WAN) access to legacy systems. But time frames may preclude redesign of host based systems in favor of an interim solution. Interim solutions may include linking workstations to host systems or data stores via technology call "middleware". Middleware delivers remote access to end users through advanced GUI technology via a mainframe communication link.
The Comsys-TIM Middleware Enabling task defines techniques and related technology to establish these host based links. This task may be applied either standalone or through one of the Comsys-TIM client/server scenarios. It resides within the Comsys-TIM Positioning stage because these techniques do not affect the basic architecture of core systems. It is only the way information is accessed that is affected.
Specific objectives of the Middleware Enabling task include:
· Facilitate workstation links via graphical user interface (GUI) to host applications
· Replace or supplement host transaction inputs with GUI presentation capabilities
· Add user friendly GUI front-end to host based systems with minimal disruption to host environment
· Support phased migration to client/server by migrating edit/validation logic to GUI based front-end
· Establish direct access to mainframe data through workstation interfaces
· Access cross functional, disparate legacy data stores via workstation/host links
· When used in conjunction with re-aggregation task, facilitate phased application rehosting to client/server environment
Entrance criteria for the Middleware Enabling task are highly scenario or project dependent as outlined below:
· Defined requirement to establish data or transaction link to host environment
· Understanding of overall client/server migration goals including:
- Is this a first step in migration source from the host
- Will a new design eventually be incorporated under this GUI front-end
- Should edit and validation be moved to client/server environment during this task
- What data migration strategies should accompany this effort
· Completion of GUI front-end created during Presentation Analysis task or similar effort
Note: In some cases, based on the situation, GUI development and middleware enabling can be approached as concurrent efforts.
· Defined client/server and server to host architectural requirements
Note: This task can assist with design finalization by offering insight into how middleware can be implemented - see step entitled "finalize middleware tool requirements".
· Finalization of workstation to host (or other links as required by technical architecture) communications protocol
Note: Following is optional and based on last step to create a direct link to relational data stores on host or server platforms.
· Generated SQL to access various related databases on target host or server platforms
The personnel and skill requirements necessary to meet the middleware enabling task objectives are identified below.
· Middleware Expert
- Knowledge of overall middleware design requirements and prior project experience required to manage and implement middleware solutions
· Telecommunications Specialist
- Knowledge of communication links (i.e., LU6.2, other) and TP monitors (i.e., CICS, IMS, etc.) on workstation and/or host environments
· Data Definition Analyst
- Knowledge of remote or local data structures being accessed via transaction facility or server based GUI
· Current Systems Expert
- Subject matter expert with knowledge of existing system functional and technical environment targeted for middleware linkage
· User Requirements Analyst
- Ability to specify and interactively respond to data or transaction links to host environment
The system components and related inputs required to initiate and complete the middleware enabling task are listed below.
· Defined GUI design and related development tool to serve as front-end link to middleware transaction software
· Client/server hardware and operating systems to support implementation effort
· Defined client/server to host and other communication environments that the middleware function under
· Initial client/server design
Technologies supporting the middleware enabling task are primarily transaction simulation facilities. These tools are used to represent information as required by this task.
Transaction simulation facility
Captures, packages, transmits and receives host based transactions to and from client/server environment using transaction simulation software. Interfaces with GUI front-end tools to package, compress and transmit host data to and from workstation environments. Features may include:
Note: It is difficult to state what is mandatory versus what is optional in a software product since a given project tends to drive this.
· Ability to interface with defined GUI client/server tools
· Generation, and optional customization, of necessary communication code
· Packing or compression and conversion of capture data
· Transparent procedure calls across network protocols to capture and return host transaction images, such as CICS or IMS TP, to legacy applications
· Ability to send and receive direct SQL commands to and from relational, SQL accessible data stores resident on host or server environment
· Optional ability to automatically design communication requirements using bundled design software
· Fault tolerance, security and backup abilities
The middleware enabling task is comprised of the following task steps:
