Activity - dataStore

Activity Type: Miscellaneous

Description

An activity that acts as a cache of data from which other activities can retrieve blocks at their own convenience. These activities must belong to the same request and the cached data does not persist after the request has completed. There are 2 different modes of operation:

1. Input from another activity - the activity reads all the data from an input as soon as possible. Other activities can then read this data from the output.
2. In-line input - data is hard-coded in blocks into the activity element. Other activities can read this data from the output.

This activity is particularly useful for requests containing a database query connected to an asynchronous delivery activity. Under normal circumstances the database query will not be evaluated until the consumer of the asynchronous delivery begins consumption. The dataStore activity can be connected between the database query and asynchrnonous delivery activity to ensure that the database query is evaluated immediately, rather than waiting until the consumer of the asynchronous delivery begins consumption.

Examples

<dataStore name="parameters">
  <item>100</item>
  <item>200</item>
  <itemCursor name="parametersOutput"/>
</dataStore>

<dataStore name="parameters">
  <input from="someInput"/>
  <itemCursor name="parametersOutput"/>
</dataStore>

Specification

Element dataStore:

• Attribute name - unique name for the activity within the scope of a request.
• One of the following types of element specifying the data to be cached:
  • Element item (one or more) - ontains cached data e.g. the first example above.
  • input (required) - data to be cached.
    • Attribute from - input stream providing the data to be cached e.g. the second example above.
• itemCursor (required) - output stream for the cached data.
  • Attribute name - name of this output stream.

Input and Output Types

• Input: input - any Java object.
• Outputs: none

Data Resource Accessor

This activity can operate with any data resource accessor.

XML Schema

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

Class

uk.org.ogsadai.activity.misc.DataStoreActivity

Client Toolkit Class

uk.org.ogsadai.client.toolkit.activity.misc.DataStore