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NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
">Object IdentifiersThe basic YAZ representation of an OID is an array of integers, terminated with the value -1. The ODR module provides two utility-functions to create and copy this type of data elements:
Creates an OID based on a string-based representation using dots (.) to separate elements in the OID.
Creates a copy of the OID referenced by the o parameter. Both functions take an ODR stream as parameter. This stream is used to allocate memory for the data elements, which is released on a subsequent call to odr_reset() on that stream. The OID module provides a higher-level representation of the family of object identifiers which describe the Z39.50 protocol and its related objects. The definition of the module interface is given in the oid.h file. The interface is mainly based on the oident structure. The definition of this structure looks like this:
The proto field takes one of the values
If you don't care about talking to SR-based implementations (few exist, and they may become fewer still if and when the ISO SR and ANSI Z39.50 documents are merged into a single standard), you can ignore this field on incoming packages, and always set it to PROTO_Z3950 for outgoing packages. The oclass field takes one of the values
corresponding to the OID classes defined by the Z39.50 standard. Finally, the value field takes one of the values
again, corresponding to the specific OIDs defined by the standard. The desc field contains a brief, mnemonic name for the OID in question. The function
takes as argument an OID, and returns a pointer to a static area containing an oident structure. You typically use this function when you receive a PDU containing an OID, and you wish to branch out depending on the specific OID value. The function
Takes as argument an oident structure - in which the proto, oclass/, and value fields are assumed to be set correctly - and returns a pointer to a the buffer as given by dst containing the base representation of the corresponding OID. The function returns NULL and the array dst is unchanged if a mapping couldn't place. The array dst should be at least of size OID_SIZE. The oid_ent_to_oid() function can be used whenever you need to prepare a PDU containing one or more OIDs. The separation of the protocol element from the remainder of the OID-description makes it simple to write applications that can communicate with either Z39.50 or OSI SR-based applications. The function
takes as argument a mnemonic OID name, and returns the /value field of the first entry in the database that contains the given name in its desc field. Finally, the module provides the following utility functions, whose meaning should be obvious:
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