Some (incomplete) ramblings about netsnmp_containers...
 
Some (incomplete) ramblings about netsnmp_containers...
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==Inroduction==
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==Introduction==
 
Containers are a generic data interface,
 
Containers are a generic data interface,
 
similar to a database. Like a database, you use an index (aka key) to access
 
similar to a database. Like a database, you use an index (aka key) to access
 
determine the sort order. The function is called with a pointer to two data
 
determine the sort order. The function is called with a pointer to two data
 
itmes, and must return a value indicating which of the two has the lesser index
 
itmes, and must return a value indicating which of the two has the lesser index
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value. So, by providing a second compare function allows the user to access the
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value.  
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data in a different order.
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==Types of Containers==
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There are several base types of containers:
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*sorted_singly_linked_list
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*unsorted_singly_linked_list
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*lifo (a last in, first out stack)
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*fifo (a first in, first out stack)
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*binary_array
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*null (for testing)
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Some of these have aliases:
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*table_container (binary_array)
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*linked_list (sorted_singly_linked_list)
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*ssll_container (sorted_singly_linked_list)
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Some types also come with a comparison routine other than the usual OID index:
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*string or string:binary_array (binary_array with a string comparison function)
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Developer Tip:
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  New types are registered via netsnmp_container_register() and netsnmp_container_register_with_compare().
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==MIB indexes vs Conainer indexes==
 
SNMP tables have indexes. A table index may have multiple components which,
 
SNMP tables have indexes. A table index may have multiple components which,
 
taken together, uniquely identify a row.
 
taken together, uniquely identify a row.
 
The default compare routine for containers assumes that the data record's first
 
The default compare routine for containers assumes that the data record's first
 
component is a netsnmp_index, so when using an OID as a key, you don't need to provide a comparison
 
component is a netsnmp_index, so when using an OID as a key, you don't need to provide a comparison
Exception encountered, of type "Error"