Activity - deliverFromGDT

Activity Type: Delivery

Description

Retrieve data from another OGSA-DAI service which implements the OGSA-DAI data transport operations via invocation of its GetFully, GetNBlocks or GetBlock operations.

This activity inputs data from a corresponding outputStream activity in the other service.

Connecting deliverFromGDT and outputStream activities

Example

<deliverFromGDT name="retrieve">
  <fromGDT streamId="sessionID:outputStreamID" resourceName="MySQLResource"
    mode="full">
    http://host:port/path/DataService
  </fromGDT>
  <toLocal name="dataSink"/>
</deliverFromGDT>

<deliverFromGDT name="retrieve">
  <fromGDT streamId="sessionID:outputStreamID" resourceName="MySQLResource"
    mode="block" numberOfBlocks="25">
    http://host:port/path/DataService
  </fromGDT>
  <toLocal name="dataSink"/>
</deliverFromGDT>

Specification

Element deliverFromGDT:

• Attribute name - unique name for the activity within the scope of a request.
• Element fromGDT (required) - the URL of an OGSA-DAI service which implements OGSA-DAI data transport operations and from which the data is to be retrieved.
  • Attribute serviceType (optional) - type of the target service.
    • wsi - the target service is OGSA-DAI WSI compliant.
    • wsrf - the target service is OGSA-DAI WSRF compliant.
    • unknown - the type of the target service is unknown. When the activity is run it will contact the service to get its WSDL and so determine the type of the service from that.
    • If omitted the value defaults to unknown.
  • Attribute resourceName - name of a data service resource exposed by the data service and from which the data originates.
  • Attribute streamId (required) - a session ID and the name of an outputStream activity running under that session on this other service.
    • The session name and stream name are expected to be conjoined with a colon (:).
  • Attribute mode (required) - the data transfer mode. One of:
    • block - the data is transferred in blocks.
    • full - all the data is transferred in one go.
  • Attribute numberOfBlocks (optional - use with mode="block" only) - the number of blocks to transfer in one go. Using this setting can improve performance of the data transfer, as a SOAP message does not have to be generated for every single block. The multiple blocks will be amalgamated into a single block before transport.
• Element toLocal (required) - output stream.
  • Attribute name - the activity's output stream.

Specifying message level security (WSRF version only)

Message level security can be used to secure the communcation between the two OGSA-DAI servers. To specify that message level security is to be used an additional GSISecureConversation element should be included in the activity specification. For example:

<deliverFromGDT name="retrieve">
  <fromGDT streamId="sessionID:outputStreamID" resourceName="MySQLResource"
    mode="full">
    http://host:port/path/DataService
  </fromGDT>
  <toLocal name="dataSink"/>
  <GSISecureConversation
    protectionLevel="integrity" 
    authorization="host" />
</deliverFromGDT>

The protectionLevel attribute specifies the GSI protection level to be used. It can take the following values:

• privacy - Use GSI Secure Conversation with message privacy . Third-parties will be unable to read or alter the data.
• integrity - Use GSI Secure Conversation with message integrity. Third-parties will be able to read the data but be unable to alter the data

The authorization attribute specifies the type of authorization the activity should peform on the remote service. It can take the following values:

• host - host authorization.
• self - self authorization.
• none - no authorization.
• Any other string - identity authorization will be used. This will require the remote server's identity to be identical to that specified in this attribute

When using message level security the client's credential will be used when the activity accesses the remote OGSA-DAI service. It is therefore essential that the client's credential is delegated to the activity. A delegation value of 'limited' or 'full' must threfore be specified in the client's security descriptor.

Input and Output Types

• Inputs: none
• Output: toLocal - any Java object received from the remote service via its data transport operations. It can be confirmed that objects of the following types delivered via data transport operations will be output from this activity:
  • java.lang.String, or
  • byte[].
  • Other Java objects are treated as java.lang.Strings

Data Resource Accessor

This activity can operate with any data resource accessor.

XML Schema

OGSA-DAI/schema/ogsadai/xsd/activities/deliver_from_gdt.xsd

Class

uk.org.ogsadai.activity.delivery.wsrf.DeliverFromGDTActivity

Client Toolkit Class

uk.org.ogsadai.client.toolkit.activity.delivery.DeliverFromDT