# Review of Web Mapping: Eras, Trends and Directions
## 3 Web Mapping Eras of Development
### Web Mapping Eras
#### 3.2.3 Services Web Mapping Era  
The development of many maps generated by map servers and a range of mapping options for users to view maps online, came with the need to package and standardize the interface to these web map servers. The purpose is to provide mapping information directly, not just to users, but also to other software programs that can consume and produce information. In the services web mapping era, component-based technologies such as Java Applets, CORBA, Microsoft.NET, etc. were used to create replaceable components with well-defined interfaces to facilitate a flexible and interoperable environment [9]. These components are assembled as web services within a service-oriented architecture (SOA), which can be published, invoked and discovered on the web. A web service receives requests, provides the data manipulation and functionality to service the request, and responds via its defined interface. Web clients can interact with the service via programs and browsers directly or indirectly with users. This paved the way for open-service application programming interfaces (APIs) which could be accessed allowing user choices or even combined with user-contributed data in the generation of mashups. An API [33; 34] provides a software-to-software interface beyond the user-to-software interface, thereby making the software accessible by a whole range of software applications. It makes it possible to combine layers from different services creating a commonly-defined and easily shareable \"front end\". API interfaces unlock online data servers and provide easier access to store, retrieve and link multiple online data repositories. They empower developers to customize and personalize web maps beyond those made available (and often limited) by vendor solutions. APIs designed specifically for making web maps include Openlayers [35], Leaflet [36], D3 [37], Google Maps API [38], Microsoft's Bing Maps [39] and ArcGIS APIs such as the ArcGIS API for JavaScript [40], which is the richest and most fully-fledged among the ESRI family. Many APIs are currently based on JavaScript and HTML. Most of them provide connections to data services but there are also examples that allow interfaces to processing services, e.g., ArcGIS APIs, taking advantage of the functionalities of the ArcToolbox, or OpenGeoSuite [41]. An early example of a web mapping service involves the United States census data, represented as TIGER files, which was released via an online web map server in 1995; this also marks the approximate commencement of this era. Through this service, users could query and map the demographic data of the United States [42]. This service was subsequently retired in May 2010 and replaced by the TIGERweb, which incorporates web mapping and streaming services [43]. In 1996, MapQuest released an address matching and traffic routing web mapping service to find business locations, optimum routes to a location, and plan trips [44]. In fact, this was one of the first examples of where web services began to provide GIS functionality, in this case geocoding and routing functions. [PERSON] developed GRASSLinks in 1995 for her PhD, which exposed GRASS desktop GIS tools to a web browser via a web server [45]. This provided the opportunity for users to access GIS functions directly from the web, paving the way for the development of Web GIS. The European Union (EU) GeoPortal was developed for the discovery, evaluation and use of existing geospatial datasets [46]. It was designed to provide, beside catalogue services, gazetteer, thesaurus, feature, portrayal (e.g., cartographic representation) and some processing services (e.g., coordinate transformation and generalization). An important contribution to web mapping services was the development of standards and specifications by the Open Geospatial Consortium (OGC).