# Package org.apache.sis.metadata.iso.acquisition

package org.apache.sis.metadata.iso.acquisition
Information about the measuring instruments, the platform carrying them, and the mission to which the data contributes. An explanation for this package is provided in the OpenGIS® javadoc. The remaining discussion on this page is specific to the SIS implementation.

## Overview

For a global overview of metadata in SIS, see the `org​.apache​.sis​.metadata` package javadoc.

Package overview
Class hierarchy | Aggregation hierarchy
--- | ---
ISO 19115 metadata `├─` Acquisition information `├─` Objective `├─` PlatformPass `├─` Event `├─` Requirement `├─` Requested date `├─` Plan `├─` Operation `├─` Platform `├─` Instrument `└─` Environmental record Code list `├─` Objective type `├─` Trigger `├─` Context `├─` Sequence `├─` Priority `├─` Geometry type `└─` Operation type | Acquisition information `├─` Requirement `│ ├─` Requested date `│ └─` Priority «code list» `├─` Objective `│ ├─` Objective type «code list» `│ └─` Platform pass `│ └─` Event `│ ├─` Trigger «code list» `│ ├─` Context «code list» `│ └─` Sequence «code list» `├─` Plan `│ ├─` Geometry type «code list» `│ └─` Operation `│ ├─` Operation type «code list» `│ └─` Platform `│ └─` Instrument `└─` Environmental record

## Null values, nil objects and collections

All constructors and setter methods accept `null` arguments. A null argument value means that the metadata element cannot be provided, and the reason for that is unspecified. Alternatively, users can specify why a metadata element is missing by providing a value created by `NilReason​.createNilObject(Class)`.

Unless otherwise noted in the Javadoc, all getter methods may return an empty collection, an empty array or `null` if the type is neither a collection or an array. Note that non-null values may be `NilObject`s.

Unless the metadata object has been marked as unmodifiable and unless otherwise noted in the Javadoc, all collections returned by getter methods are live: adding new elements in the collection modify directly the underlying metadata object.

Since:
  0.3

- Related Packages
  Package
  Description
  org.apache.sis.metadata.iso
  Root package for ISO 19115 metadata about resources (data or services).
- Classes
  Class
  Description
  DefaultAcquisitionInformation
  Designations for the measuring instruments, the platform carrying them, and the mission to which the data contributes.
  DefaultEnvironmentalRecord
  Information about the environmental conditions during the acquisition.
  DefaultEvent
  Identification of a significant collection point within an operation.
  DefaultInstrument
  Designations for the measuring instruments.
  DefaultObjective
  Describes the characteristics, spatial and temporal extent of the intended object to be observed.
  DefaultOperation
  Designations for the operation used to acquire the dataset.
  DefaultPlan
  Designations for the planning information related to meeting the data acquisition requirements.
  DefaultPlatform
  Designation of the platform used to acquire the dataset.
  DefaultPlatformPass
  Identification of collection coverage.
  DefaultRequestedDate
  Range of date validity.
  DefaultRequirement
  Requirement to be satisfied by the planned data acquisition.