Web GIS was not based on web services; instead, it consisted mostly of stand-alone websites where GIS data and functions were available only to their own clients and couldn’t be reused in other systems. This situation greatly limited the reusability of Web GIS resources. As a result, the level of effort to create Web GIS apps was high. In the later 1990s, web services technology was conceived. A web service is essentially a program that runs on a web server and exposes programing interfaces for clients to consume over the web. Web services have many advantages, especially their flexibility in being reused and remixed in many web apps.
Over the years, the main web services interface style has evolved from Simple Object Access Protocol (SOAP) to Representational State Transfer (REST). REST is considered “the command line of the web,” and relies on URLs to send requests and pass parameters. REST became the preferred web service interface type because of its simplicity and efficiency for the web environment. With REST, every resource has a URL, also called endpoint, and can be accessed via this URL. Therefore, you can add ArcGIS web services to the ArcGIS Online map viewer via their URLs. You will learn more about REST in other chapters later in this book.
The GIS industry quickly adopted web services technology and reformed Web GIS products based on web services architecture in the early 2000s. Today’s Web GIS products are designed to support the publication, discovery, and use of GIS web services. A GIS service represents a GIS resource—such as a map, locator, or toolbox—that is located on the server and is made available to client applications. For example, ArcGIS Online provides collections of ready-to-use GIS services. ArcGIS Online and ArcGIS Enterprise allow publishers to publish many types of GIS services. ArcGIS Online and Portal for ArcGIS allow users to discover and use GIS services in web maps, web apps, and mobile apps. This chapter focuses on feature services or feature layers. You will learn about other types of services in other chapters of this book.
Feature services and hosted feature layer
Feature services and hosted feature layers are the most commonly used layer type for operational layers. A feature service in ArcGIS often refers to a feature service published to ArcGIS for Server. A hosted feature layer refers to a feature service published to ArcGIS Online or Portal for ArcGIS. “Layer” here refers to a content item in ArcGIS Online and Portal for ArcGIS. “Hosted” refers to the fact that they are hosted in the ArcGIS Online cloud or the underlying data is stored in the ArcGIS Data Store. Feature services and hosted feature layers can support read and/or write data access. This chapter will focus on the read-only hosted feature layers. You will learn about the writable feature layers in the mobile GIS chapter.
You can publish hosted feature layers to ArcGIS Online or Portal for ArcGIS from ArcGIS Pro, or simply a web browser.
Create a feature layer from your own data (for example, CSV, shapefiles, GeoJSON, and file geodatabase): Go to ArcGIS Online or Portal for ArcGIS Content > My Content page, click Add Item (see section 2.1).
Duplicate an existing feature layer without needing your own data: This process will create a new empty layer of the same schema, in other words, containing the same attribute fields as the “mother” layer. This approach is useful if you can find a “mother” layer that matches your needs or if you want to use the “mother” feature layer again and again. You can go to ArcGIS Online or Portal for ArcGIS Content > My Content page, click Create > Feature Layer, and choose From Template, From Existing Layer, or From URL.
Create an empty feature layer and define your own fields interactively: You will go to the ArcGIS for Developers site (http://developers.arcgis.com), log in with your ArcGIS Online account, click the plus button at the top, and select New Layer. The website will walk you through the steps to create a new feature layer. You will have the chance to specify the layer title, feature type (points, lines, or polygons), extent, attribute fields, and its default symbols.
Create an empty feature layer and define your own fields interactively using ArcGIS for Developers site.
Living Atlas of the World
Traditionally, you had to collect or prepare all or most of the data for your application and analysis. Today, you can find rich content from the ArcGIS Online catalog. You can use Living Atlas contents as your operational and, occasionally, basemap layers.
Living Atlas of the World is a curated subset of ArcGIS Online information items contributed to and maintained by Esri and the ArcGIS user community. The Living Atlas has thousands of layers covering many topics.
Living Atlas is a dynamic collection of thousands of maps, data, imagery, tools, and apps produced by ArcGIS users worldwide and by Esri and its partners. Living Atlas is the foremost collection of authoritative, ready-to-use global geographic information ever assembled. You can combine content from this repository with your own data to create powerful new maps and apps. You can use these maps and apps when you perform diverse analyses in ArcGIS Online, without having to collect the data yourself.
Living Atlas provides the following content categories:
Basemaps: Reference maps for the world and the foundation for GIS apps.
Imagery: Recent high-resolution imagery for the world, daily multispectral imagery, and near real-time imagery for major events, such as natural disasters.
Demographics and lifestyles: Maps and data for the United States and more than 120 other countries reveal insights about populations and their behaviors.
Boundaries and places: Boundaries help define where people live and work, and these layers span a variety of scales, from neighborhood to continental extents.
Landscape: Data reflect both the natural environment and man-made influences to support land-use planning and management.
Transportation: The collection of maps and layers reveals how people move between places.
Oceans: Data on sea surface and floor temperature, distance to shore, ecological marine units, floor geomorphology, and various chemical concentration maps.
Urban systems: More than half of the world’s population now lives in cities, and these layers allow analysis of how population impacts the world.
Earth observations: These observations depict our planet’s extreme events and conditions, from severe weather to earthquakes and fires.
Historical maps: These maps reflect the changing physical, political, and cultural aspects of our world over time.
The word “living” in the name Living Atlas indicates that content is continuously updated in minutes or hours (for example, live traffic and real-time earthquakes), days or weeks (for example, remote sensing imageries), and regularly as new content becomes available from the contributing community. For more information on the Living Atlas, go to http://doc.arcgis.com/en/living-atlas/about.
Layer configuration
Smart mapping
Your layers must be displayed in appropriate styles for you and your end users to discover the hidden patterns and deliver the intended messages. If your layers do not come with styles or you do not like their existing styles, you can change styles (although
