Frequently asked questions

General

What is UNICORE?

UNICORE is a Grid middleware, enabling secure access to distributed resources such as compute servers or file storages. For a general overview, please visit the UNICORE.eu website

What is UNICORE/X?

UNICORE/X is the central server of a UNICORE 6 site. It consists of a web service engine, a WSRF hosting environment and an execution management system (XNJS) offering access to physical target systems.

Which services are provided by UNICORE/X?

All the UNICORE 6 atomic services (TargetSystemFactory, TargetSystem, JobManagement, StorageManagement, FileTransfer), and a Registry services are a core part of UNICORE/X. Additionally, the OGSA-BES service is available, that provides a job submission interface as s tandardised by the Open Grid Forum

What about workflow?

A UNICORE workflow system is available, that offers enhanced flexibility, by using runtime resource brokering and allocation. This is based on work done in the Chemomentum project. Please see the download area for more information.

Security

What kind of security measures does UNICORE/X provide?

The simplest security measure in UNICORE/X is client authenticated SSL. This means all communication partners need X.509 certificates issued by a trusted certification authority.

UNICORE/X offers access control to its services. The user id to be used on the underlying target system and other user attributes can be retrieved from a user database (UUDB). Access control policies are expressed using the XACML 1.0 standard.

Alternative or additional security mechanisms can be plugged in. These plug-in points include the authorisation component and the XACML policy decision points. Furthermore, additional security handlers can be plugged into the web service engine.

Data transfer

What data transfer mechanisms are supported?

In the default configuration, UNICORE/X offers data transfer using OGSA ByteIO and the UNICORE 6 "baseline" transfer, which transfers files using HTTP.

An add-on module is under development that leverages the high-performance UDT protocol for filetransfers.

For data-staging, GridFTP is supported, but needs additional configuration, see the Proxy guide for details.

What data transfer mechanism should I choose?

For best performance, BFT should be used.

Using the default ByteIO transfer passes the data through the full UNICORE stack; thus, security is maximal, extra configuration is minimal, but unfortunately the performance is limited to around 500kB/sec. Using baseline transfer (BFT) offers a much better performance of several MB/sec.