# &adminguide;

## Overview

This module is an implementation of a cache system designed to work with a Couchbase server. It uses the libcouchbase client library to connect to the server instance, It uses the Key-Value interface exported from the core.

## Advantages

- memory costs are no longer on the server

- many servers can be used inside a cluster, so the memory is virtually unlimited

- the cache is 100% persistent. A restart of OpenSIPS server will not affect the DB. The CouchBase DB is also persistent so it can also be restarted without loss of information.

- CouchBase is an open-source project so it can be used to exchange data with various other applications

- By creating a CouchBase Cluster, multiple OpenSIPS instances can easily share key-value information

## Limitations

- keys (in key:value pairs) may not contain spaces or control characters

## Dependencies

### &osips; Modules

None.

### External Libraries or Applications

The following libraries or applications must be installed before running &osips; with this module loaded:

- libcouchbase >= 2.0:

  libcoucbase can be downloaded from http://www.couchbase.com/develop/c/current

## Exported Parameters

### `cachedb_url` (string)

The urls of the server groups that OpenSIPS will connect to in order to use the from script cache_store,cache_fetch, etc operations. It can be set more than one time. The prefix part of the URL will be the identifier that will be used from the script. The format of the URL is couchbase[:identifier]://[username:password@]IP:Port/bucket_name

#### Set `cachedb_url` parameter

    ...
    modparam("cachedb_couchbase", "cachedb_url","couchbase:group1://localhost:6379/default");
    modparam("cachedb_couchbase", "cachedb_url","couchbase:cluster1://random_url:8888/my_bucket");
    #Multiple hosts
    modparam("cachedb_couchbase", "cachedb_url","couchbase:cluster1://random_url1:8888;random_url2:8888;random_url3:8888/my_bucket");
    ...

### `timeout` (int)

The max duration in microseconds that a couchbase op is expected to last. Default is 3000000 ( 3 seconds )

#### Set `timeout` parameter

    ...
    modparam("cachedb_couchbase", "timeout",5000000);
    ...

### `exec_threshold` (int)

The maximum number of microseconds that a couchbase query can last. Anything above the threshold will trigger a warning message to the log

Default value is 0 ( unlimited - no warnings ).

#### Set `exec_threshold` parameter

    ...
    modparam("cachedb_couchbase", "exec_threshold", 100000)
    ...

### `lazy_connect` (int)

Delay connecting to a bucket until the first time it is used. Connecting to many buckets at startup can be time consuming. This option allows for faster startup by delaying connections until they are needed. This option can be dangerous for untested bucket configurations/settings. Always test first without lazy_connect. This option will show errors in the log during the first access made to a bucket. Default is 0 ( Connect to all buckets on startup )

#### Set `lazy_connect` parameter

    ...
    modparam("cachedb_couchbase", "lazy_connect", 1);
    ...

### Use CouchBase servers

    ...
    cache_store("couchbase:group1","key","$ru value");
    cache_fetch("couchbase:cluster1","key",$avp(10));
    cache_remove("couchbase:cluster1","key");
    ...

### Exported Functions

The module does not export functions to be used in configuration script.