- A Globus Primer
- Globus Is Modular!
- Installing GT
- Platform Notes
- GT Developer's Guide
- GT User's Guide
- Migrating Guides
- GSI C
- GSI Java
- Java WS A&A
- C WS A&A (coming soon)
- Delegation Service
- Bloom filter
Compression scheme used by the Replica Location Service (RLS) that is intended to reduce the size of soft state updates between Local Replica Catalogs (LRCs) and Replica Location Index (RLI) servers. A Bloom filter is a bit map that summarizes the contents of a Local Replica Catalog (LRC). An LRC constructs the bit map by applying a series of hash functions to each logical name registered in the LRC and setting the corresponding bits.
- Certificate Authority ( CA )
An entity that issues certificates. [fixme - flesh out]
A public key plus information about the certificate owner bound together by the digital signature of a CA. In the case of a CA certificate, the certificate is self signed, i.e. it was signed using its own private key.
A process that sends commands and receives responses. Note that in GridFTP, the client may or may not take part in the actual movement of data.
A job scheduler mechanism supported by GRAM. See http://www.cs.wisc.edu/condor/ for more information.
- extended block mode (MODE E)
MODE E is a critical GridFTP components because it allows for out of order reception of data. This in turn, means we can send the data down multiple paths and do not need to worry if one of the paths is slower than the others and the data arrives out of order. This enables parallelism and striping within GridFTP. In MODE E, a series of “blocks” are sent over the data channel. Each block consists of:
- an 8 bit flag field,
- a 64 bit field indicating the offset in the transfer,
- and a 64 bit field indicating the length of the payload,
- followed by length bytes of payload.
Note that since the offset and length are included in the block, out of order reception is possible, as long as the receiving side can handle it, either via something like a seek on a file, or via some application level buffering and ordering logic that will wait for the out of order blocks.
- grid map file
A file containing entries mapping certificate subjects to local user names. This file can also serve as a access control list for GSI enabled services and is typically found in
/etc/grid-security/grid-mapfile. For more information see the Gridmap section here.
- job description
Term used to describe a GRAM4 job for GT4.
- job scheduler
See the term scheduler.
- Local Replica Catalog (LRC)
Stores mappings between logical names for data items and the target names (often the physical locations) of replicas of those items. Clients query the LRC to discover replicas associated with a logical name. Also may associate attributes with logical or target names. Each LRC periodically sends information about its logical name mappings to one or more RLIs.
See also RLI.
- logical file name
A unique identifier for the contents of a file.
A job scheduler mechanism supported by GRAM.
For more information, see http://www.platform.com/Products/Platform.LSF.Family/Platform.LSF/.
A job that is itself composed of several executable jobs; these are processed by the MMJS subjob.
See also MMJS subjob.
- Portable Batch System (PBS)
A job scheduler mechanism supported by GRAM. For more information, see http://www.openpbs.org.
- physical file name
The address or the location of a copy of a file on a storage system.
- proxy certificate
A short lived certificate issued using a EEC. A proxy certificate typically has the same effective subject as the EEC that issued it and can thus be used in its place. GSI uses proxy certificates for single sign on and delegation of rights to other entities.
For more information about types of proxy certificates and their compatibility in different versions of GT, see http://dev.globus.org/wiki/Security/ProxyCertTypes.
- Replica Location Index (RLI)
Collects information about the logical name mappings stored in one or more Local Replica Catalogs (LRCs) and answers queries about those mappings. Each RLI periodically receives updates from one or more LRCs that summarize their contents.
- Resource Specification Language (RSL)
Term used to describe a GRAM job for GT2 and GT3. (Note: This is not the same as RLS - the Replica Location Service)
- RLS attribute
Descriptive information that may be associated with a logical or target name mapping registered in a Local Replica Catalog (LRC). Clients can query the LRC to discover logical names or target names that have specified RLS attributes.
A process that receives commands and sends responses to those commands. Since it is a server or service, and it receives commands, it must be listening on a port somewhere to receive the commands. Both FTP and GridFTP have IANA registered ports. For FTP it is port 21, for GridFTP it is port 2811. This is normally handled via inetd or xinetd on Unix variants. However, it is also possible to implement a daemon that listens on the specified port. This is described more fully in in the Architecture section of the GridFTP Developer's Guide.
SOAP provides a standard, extensible, composable framework for packaging and exchanging XML messages between a service provider and a service requester. SOAP is independent of the underlying transport protocol, but is most commonly carried on HTTP. See the SOAP specifications for details.
- stream mode (MODE S)
The only mode normally implemented for FTP is MODE S. This is simply sending each byte, one after another over the socket in order, with no application level framing of any kind. This is the default and is what a standard FTP server will use. This is also the default for GridFTP.
- third party transfers
In the simplest terms, a third party transfer moves a file between two GridFTP servers.
The following is a more detailed, programmatic description.
In a third party transfer, there are three entities involved. The client, who will only orchestrate, but not actually take place in the data transfer, and two servers one of which will be sending data to the other. This scenario is common in Grid applications where you may wish to stage data from a data store somewhere to a supercomputer you have reserved. The commands are quite similar to the client/server transfer. However, now the client must establish two control channels, one to each server. He will then choose one to listen, and send it the PASV command. When it responds with the IP/port it is listening on, the client will send that IP/port as part of the PORT command to the other server. This will cause the second server to connect to the first server, rather than the client. To initiate the actual movement of the data, the client then sends the RETR “filename” command to the server that will read from disk and write to the network (the “sending” server) and will send the STOR “filename” command to the other server which will read from the network and write to the disk (the “receiving” server).
See Also client/server transfer.
- transport-level security
Uses transport-level security (TLS) mechanisms.
- Web Services Addressing (WSA)
The WS-Addressing specification defines transport-neutral mechanisms to address web services and messages. Specifically, it defines XML elements to identify web service endpoints and to secure end-to-end endpoint identification in messages. See the W3C WS Addressing Working Group for details.
- Web Services Description Language (WSDL)
WSDL is an XML document for describing Web services. Standardized binding conventions define how to use WSDL in conjunction with SOAP and other messaging substrates. WSDL interfaces can be compiled to generate proxy code that constructs messages and manages communications on behalf of the client application. The proxy automatically maps the XML message structures into native language objects that can be directly manipulated by the application. The proxy frees the developer from having to understand and manipulate XML. See the WSDL 1.1 specification for details.
- Web Services Resource Framework (WSRF)
Web Services Resource Framework (WSRF) is a specification that extends web services for grid applications by giving them the ability to retain state information while at the same time retaining statelessness (using resources). The combination of a web service and a resource is referred to as a WS-Resource. WSRF is a collection of different specifications that manage WS-Resources.
This framework comprises mechanisms to describe views on the state (WS-ResourceProperties), to support management of the state through properties associated with the Web service (WS-ResourceLifetime), to describe how these mechanisms are extensible to groups of Web services (WS-ServiceGroup), and to deal with faults (WS-BaseFaults).
Extensible Markup Language (XML) is standard, flexible, and extensible data format used for web services. See the W3C XML site for details.