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Dyalog File Server
For sharing data
The Dyalog File Server (DFS) allows users to share data using a centralised server, rather than sharing files over a LAN. The DFS is able to serve both Dyalog Component Files (DCF) and native operating system files, removing the requirement for clients to have network access to file storage. This is a storage mechanism for APL arrays. The DFS offers users a variety of advantages within the realms of security, performance, operations, and recovery.
What is the Dyalog File Server?
All versions of Dyalog include a built-in “array store” called the Component File system (DCF), where APL arrays are stored in numbered components. Because arrays are stored in the internal form used by the interpreter, component files are a highly efficient mechanism. Dyalog users have used the flexibility of component files to create a wide variety of data storage mechanisms.
The Dyalog File Server (DFS) is a client/server implementation of DCF. Internally, the DFS manages the same component files that you would otherwise access over the network. This means that migration to the DFS does not require any file conversions: simply remove the file shares that currently give access to the files and start a DFS server that is able to see the files and provide secure access to them.
Particularly in multi-user situations, DFS provides a number of advantages over the DCF including:
Security
When normal DCF files are shared on a network drive, any program running on the client can access the file. For example, a DCF file can be opened with a text editor, without regard to component file access settings. Damage to the binary structure of the file can easily result. The DFS removes all direct client access to the files it manages; only processes on the server side can access the files. File access matrices set by the application are strictly enforced and cannot be circumvented by the client. In addition, secure sockets can be used between the client and server processes.
Performance
Any one DFS file is handled by a single process. This allows that process to exclusively open the file and cache index blocks and other frequently used data. No file locking is required, resulting in significantly higher throughput, especially for files that are shared by several users. Component file holds are managed by a separate process that implements a fair queue, unlike the mechanism used for files shared on a network drive.
Operations
DFS is managed using a web-based console which provides real-time performance reporting. A command-line API enables integration of the starting and stopping of the DFS into other management systems.
Recovery
DFS recovers automatically from network problems and server restarts. File ties are preserved, and application execution can continue as soon as the server becomes available.
Dyalog File Server
DFS Features
DFS supports all the component file and native file functions in Dyalog. In addition, a number of features of the mainframe “SHAREFILE/AP” system have been added, such as FHIST, FWHOIS and FUSERNO. Additional utility functions for creating, deleting and removing folders and manipulating attributes of native files are also included.
Watch a Demonstration
Morten Kromberg introduces the Dyalog File Server
Licensing
Dyalog File Server FAQ
What is the Dyalog File Server (DFS)?
The Dyalog File Server is a client/server implementation of the Dyalog Component File (DCF) system. It allows multiple users to access and share APL arrays via a secure server, instead of relying on direct file access over a local network.
Why would I use DFS instead of regular DCF files?
DFS provides better security, performance, and reliability in multi-user environments. It prevents direct access to component files, improves throughput by avoiding file locking, and automatically recovers from network or server issues.
How is DFS managed?
DFS includes a web-based management console that provides real-time reporting and operational oversight, making it easier to monitor usage and system health.
Can DFS be used with both component and native files?
DFS supports all standard component file and native file functions in Dyalog, along with additional utility functions and features inspired by SHAREFILE/AP.
