Communication Concepts

Your application, a client in this case, sends a request to the ISBNdb.com server asking to return some data. The request is self consistent and does not rely on any previous history, it includes everything required for the server to produce a response. After the server processes the request and sends out a response the session ends -- in fact the next response may be handled by a different server behind the scenes (as a side note, technically, your application can use keep-alive mechanism to keep the communication channel up between sessions -- but each message exchange in such channel is nonetheless completely independent).

Each request sent to the server includes a couple of variables that you set to various values depending on the task at hand. Variables can be classified into three major groups:

1. Identification variables -- these identify your account and/or application to the server. The server implies some limits on how much requests a given account or application can send. Typically, this sets a daily limit on the number of requests that gets reset every night (although custom agreements can override such limits or impose their own).

2. Data set definition variables -- these specify to the server what data elements your application is interested in. These can include keywords, collection names, IDs, relations between data, etc. The end result could be one of more books satisfying some given criteria.

3. Response formatting variables -- these define what parts of the data should be delivered in the response. For instance, for a book this can specify whether your application is interested in price history, library data, subject IDs, similar books, etc.

Access Protocol Specifics

Web request protocol

In this protocol you specify your request by fetching a document from a specific URL and provide variable as a standard CGI parameters. Here is what the URL usually looks like:

http://isbndb.com/api/books.xml?access_key=12345678&index1=isbn&value1=0596002068

The response is an XML formatted message similar in essense to this example:

<?xml version="1.0" encoding="UTF-8"?>
<ISBNdb server_time="2005-02-25T23:03:41">
 <BookList total_results="1" page_size="10" page_number="1" shown_results="1">
  <BookData book_id="somebook" isbn="0123456789">
   <Title>Interesting Book</Title>
   <TitleLong>Interesting Book: Read it or else..</TitleLong>
   <AuthorsText>John Doe</AuthorsText>
   <PublisherText>Acme Publishing</PublisherText>
  </BookData>
 </BookList>
</ISBNdb>

Unless otherwise mentioned, examples and descriptions below are using this access protocol as the only one publically available at the moment.

XML-RPC

Not yet implemented, see below if you are interested in having this protocol available.

Formal web services with SOAP and WSDL

Not yet implemented, see below if you are interested in having this protocol available.

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