PropelZ™ enables bidirectional mainframe file system integration — read data from VSAM and sequential files, transform it through any processing pipeline, then write it back to new mainframe datasets with comprehensive allocation and management capabilities. The output side closes the loop, returning data to native z/OS structures.
PropelZ excels at reading data from mainframe file systems — VSAM files, sequential datasets, tape archives, and GDGs. Customers use these capabilities to migrate data to cloud platforms, feed analytics systems, and integrate with modern applications.
But what happens when you need to go the other direction?
Consider this scenario: You’ve used PropelZ to migrate critical data from your mainframe to a cloud analytics platform. Your team has processed that data, applied business rules, and generated insights. Now you need to bring the results back to z/OS for comparison with original data or for use by existing mainframe applications.
That reverse journey traditionally required separate tools, custom processes, or complex workarounds. PropelZ’s VSAM and Sequential File Output connectors change that equation entirely.
From One-Way Migration to Bidirectional Integration
Traditional mainframe integration tools treat data movement as a one-way street: read from the mainframe, send to modern platforms, and never look back. This approach works for pure migration projects but falls short when enterprises need true bidirectional integration.
The PropelZ output connectors enable scenarios that were previously complex or impossible:
- Round-trip Analytics: Query databases, apply transformations, then write results to VSAM files for mainframe application processing.
- Cloud Processing with Mainframe Results: Process data in cloud environments, then return the enhanced datasets to z/OS in native file formats.
- Data Validation and Comparison: Migrate data for modernization projects, then bring processed results back to mainframe formats for validation against original systems.
- Hybrid Application Support: Enable modern applications to generate data that mainframe systems can consume directly, without format conversion or intermediate steps.
Solving the Allocation Complexity Challenge
Creating mainframe datasets isn’t just about writing records to files. VSAM files require precise specifications for key structures, indexing strategies, buffer allocation, and performance optimization. Sequential files need proper disposition handling, GDG management, and tape volume coordination.
The complexity is real: allocating a VSAM file can involve hundreds of possible parameters. How big are the keys, where do they sit in the record, how large should the index be relative to the data, how much buffer space is needed — the list of options is extensive, and getting them wrong can affect both functionality and performance.
Writing the records themselves is the easy part. The heavy lifting is the allocation. Rather than forcing customers to become experts in mainframe file allocation, PropelZ leverages IBM’s own utilities to do that work.
The PropelZ connector begins with disposition: is this a brand-new file to create, an existing file to overwrite, or an existing file to append new records to? From there, the process splits along two paths:
- For VSAM files, customers provide the control statements they would normally give to IBM’s IDCAMS utility — define a keyed VSAM file with a given key length and the full range of syntax that utility supports. PropelZ runs the IBM utility under the covers to create exactly the file specified, then begins writing data records to it.
- For sequential files, GDGs, and tapes, the process uses IBM’s standard file allocation syntax — the familiar, highly standardized command-line approach for allocating new datasets on z/OS. Customers specify disposition, space, and other attributes using parameters they already know, and PropelZ handles the allocation before writing data. Tape brings its own considerations — which volume to use, whether it’s a scratch tape, whether you’re writing a new file onto an existing tape — and the connector handles that subset of complexity the same way.
Beyond File Creation: Format Intelligence
Writing data to mainframe files involves more than allocation. Different platforms handle text encoding, record structures, and data types differently. The PropelZ output connectors include intelligent format handling that bridges these differences automatically.
A concrete example: text data arriving from a distributed platform often comes as variable-length strings, where a new line separates one record from the next. VSAM files, by contrast, typically use fixed-length records. Writing that text data into a VSAM file requires padding and structural adjustment so each record fits the target format correctly. The connector handles this transformation automatically.
Binary data, numeric formats, and character encoding all receive similar treatment. The goal is making cross-platform integration seamless without requiring customers to understand the low-level differences between mainframe and distributed data representations.
Closing Integration Loops
These output capabilities address real customer requirements. A representative case: an enterprise used PropelZ to migrate a large volume of data for processing in modern environments, then needed to bring the processed results back to z/OS to compare them against original systems. The output connectors provide a native way to return data in the form of VSAM and sequential files, rather than relying on custom solutions or accepting one-way data movement.
Other organizations want to leverage cloud processing power while maintaining mainframe applications that expect data in traditional formats. In both situations, PropelZ supports the complete round trip within a single integration platform.
Architectural Integration
The output connectors integrate seamlessly with PropelZ’s existing transformation pipeline. Any data source that PropelZ can read — databases, cloud storage, APIs, other mainframe files — can now feed mainframe file creation processes.
This means complex transformation workflows can culminate in mainframe dataset creation. Start with a JDBC query against a cloud database, apply business rules through PropelZ transformations, then write the results to a new VSAM file for mainframe application consumption.
The same integration patterns that make PropelZ effective for reading mainframe data now work in reverse, enabling truly bidirectional mainframe integration. The input and output connectors are mirror images of one another, working from opposite ends of the same pipeline.
A z/OS-Native Capability
Because VSAM exists only on z/OS and constructs like GDGs are likewise specific to the platform, the PropelZ output connector is a z/OS capability. Creating native mainframe file structures is inherently tied to the mainframe environment, and the connector is built to operate there.
Enterprise Integration Maturity
The addition of comprehensive output capabilities represents a maturation of enterprise integration thinking. Early cloud migration projects often focused on one-way data movement: get data off the mainframe and into modern systems as quickly as possible.
As those migrations mature, organizations discover they need more nuanced approaches. Some data needs to flow both directions. Some applications require hybrid processing where modern tools enhance data that mainframe systems then consume. Some validation scenarios require round-trip processing to verify modernization approaches.
The PropelZ output connectors enable these sophisticated integration patterns without requiring customers to manage multiple tools or develop custom solutions for each scenario.
Beyond Migration: Integration Strategy
With comprehensive input and output capabilities, PropelZ transforms from a migration tool into a true integration platform. Organizations can design data architectures that leverage the strengths of both mainframe and distributed systems without being constrained by platform boundaries.
Modern analytics platforms excel at processing large datasets and applying advanced techniques. Mainframe systems provide unmatched reliability and transaction processing capabilities. Instead of choosing between these strengths, enterprises can now design hybrid approaches that combine them strategically.
The result is integration architecture that adapts to business requirements rather than forcing business processes to adapt to platform limitations. Data flows where it provides the most value, processed by systems optimized for specific tasks, then shared seamlessly across the enterprise.
This represents the true promise of hybrid computing: leveraging the best capabilities of every platform while maintaining the integration flexibility to evolve as requirements change.
Next Steps
- Schedule a PropelZ briefing.
- Watch a demo of PropelZ.
- Try PropelZ.
Learn More
- Visit our Customer Briefing Center.
- Review all VirtualZ Use Cases, Thought Leadership papers, and Solution Briefs.
- Explore our YouTube channel, podcasts, and blog.
- Still have questions? Contact us.
