Working with HTTP Web Services
ABC's HTTP Web Services interface is based on sending and receiving data from remote servers using the operations of HTTP directly. Pure HTTP web service is a style, not a standard. However, this style implements popular standards – URL, XML and HTTP.
To get data from the server, a URL containing an HTTP GET request is sent to the server. The response contains an XML message. This XML message can be parsed.
If you have been exposed to thin-client application development (i.e. applications executing within a Browser over the internet) then you have been leveraging several of the core protocols important to ABC's HTTP Web Services implementation. The main advantage of this approach is simplicity.
The core advantages of HTTP web services are:
- Easy to build – no toolkits required. Many development environments (e.g. Java, .Net, C++, etc.) provide support for building software to send and receive HTTP requests over the internet. All major programming languages include HTTP libraries for building applications that can send and receive HTTP.
- Human readable results – the response is structured with XML. The web service response uses markup tags to identify the data. This is much easier to read compared to the typical structured file layout style of moving data between systems. With a structured file layout, the data is organized by start and end positions within the file.
For example, the following layout contains three pieces of information: member number, join date, and last check in date:
2345671203200701052008
The same information in XML could appear like this:
<member number>234567</member number>
<join date>12032007</join date>
<last checkin date>01052008</last checkin date>
- Lightweight – not a lot of extra XML markup. The HTTP GET/POST request and response objects use XML to format the data. SOAP based web services (compared to HTTP) require additional overhead and XML. There are advantages to building SOAP based web services. This document does not present any of those benefits.
- XML parsing - all major programming languages include libraries to support reading and parsing of XML data.
- Easy to consume – because no special software needed. Requesting data through HTTP and consuming the response is accomplished every time you make a request through a Browser over the internet. And more specifically, many current web applications, e.g., book ordering services, online dictionary services, etc. are HTTP-based web services.
- Stateless – do not need to retain any stored context within your client application. Each Web Service request you make is a new request.
The documentation for individual HTTP services describes the formats required and returned by each parameter. For your convenience, you may also want a reference list of all parameters on a single page.
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