Select a Pattern Agnostic Capability Agnostic Context Agnostic Sub-Controller Asynchronous Queuing Atomic Service Transaction Brokered Authentication Canonical Expression Canonical Protocol Canonical Resources Canonical Schema Canonical Schema Bus Canonical Versioning Capability Composition Capability Recomposition Compatible Change Compensating Service Transaction Composition Autonomy Concurrent Contracts Contract Centralization Contract Denormalization Cross-Domain Utility Layer Data Confidentiality Data Format Transformation Data Model Transformation Data Origin Authentication Decomposed Capability Decoupled Contract Direct Authentication Distributed Capability Domain Inventory Dual Protocols Enterprise Inventory Enterprise Service Bus Entity Abstraction Event-Driven Messaging Exception Shielding Federated Endpoint Layer File Gateway Functional Decomposition Intermediate Routing Inventory Endpoint Legacy Wrapper Logic Centralization Message Screening Messaging Metadata Metadata Centralization Multi-Channel Endpoint Non-Agnostic Context Official Endpoint Orchestration Partial State Deferral Partial Validation Policy Centralization Process Abstraction Process Centralization Protocol Bridging Proxy Capability Redundant Implementation Reliable Messaging Rules Centralization Schema Centralization Service Agent Service Broker Service Callback Service Data Replication Service Decomposition Service Encapsulation Service Facade Service Grid Service Instance Routing Service Layers Service Messaging Service Normalization Service Perimeter Guard Service Refactoring State Messaging State Repository Stateful Services Termination Notification Three-Layer Inventory Trusted Subsystem UI Mediator Utility Abstraction Validation Abstraction Version Identification Overview     History     Acknowledgements     Podcasts     Notification Form     Feedback Form     Press Release #1     Press Release #2     Press Release #3 Master SOA Design Pattern Catalog     Master Pattern List (alphabetical)     Master Pattern List (by category)     Master Pattern List with Page Numbers (PDF)     Master Pattern List (Text)     Pattern Notation     Pattern Profiles     Symbol Legend     Pattern Contribution Form SOA Candidate Patterns     SOA Patterns Review Committee     Candidate Patterns Overview     Candidate Patterns List     Candidate Pattern Contribution Form     Candidate Pattern Feedback Form     SOA Pattern Template Design Pattern Basics     What's a Design Pattern?     What's a Design Pattern Language?     What's a Compound Pattern? Supplemental     SOA Patterns and Application Technologies     SOA Design Patterns Historical Influences     SOA Design Patterns and Design Principles     SOA Design Patterns and Design Granularity     Legal Resources     Design Patterns Publications     Reference Posters     SOAPrinciples.com     WhatIsSOA.com     SOA Visio Stencil File Gateway (Roy) Home > Legacy Encapsulation Patterns > File Gateway How can service logic interact with legacy systems that can only share information by exchanging files?   Problem Data records contained in flat files produced by a legacy system need to be processed individually by service logic, but legacy systems are not capable of directly invoking services. Conversely, service logic may need to produce information for the legacy system, but building file creation and transfer functionality into the service can result in an inflexible design. Solution Intermediary two-way file processing logic is positioned between the legacy system and the service. Application For inbound data the file gateway processing logic can detect file drops and leverage available broker features to perform Data Model Transformation and Data Format Transformation. On the outbound side, this logic intercepts information produced by services and packages them (with possible transformation) into new or existing files for consumption by the legacy system. Impacts The type of logic provided by this pattern is unsuitable when immediate replies are required by either service or legacy system. Deployment and governance of two-way file processing logic can further add to operational complexity and may require specialized administration skills. Principles Service Loose Coupling Architecture Service File gateway logic acts as a mediator between a service and a flat-file-based legacy system. Related Patterns in This Catalog Data Format Transformation (Erl), Data Model Transformation (Erl), Event-Driven Messaging (Little, Rischbeck, Simon), Legacy Wrapper (Erl, Roy), Protocol Bridging (Little, Rischbeck, Simon), Service Agent (Erl), Service Callback (Karmarkar) Related Patterns in Other Catalogs File Transfer (Hohpe, Woolfe) Related Service-Oriented Computing Goals Increased Vendor Diversification Options, Reduced IT Burden This page contains excerpts from: SOA Design Patterns by Thomas Erl Foreword by Grady Booch With contributions from David Chappell, Jason Hogg, Anish Karmarkar, Mark Little, David Orchard, Satadru Roy, Thomas Rischbeck, Arnaud Simon, Clemens Utschig, Dennis Wisnosky, and others. (ISBN: 0136135161, Hardcover, Full-Color, 400+ Illustrations, 865 pages) For more information about this book, visit www.soabooks.com.

Home    SOA Books    SOA Magazine    What is SOA?    SOA Principles    SOASchool.com    SOA Glossary	Copyright © 2007-2009 SOA Systems Inc.