Redis

Readme

This plugin allows you to connect to a redis server. If you don't know what redis is, I'd suggest reading up here in detail: redis.io.Key features:

• This plugin supports almost all commands
• Including pubsub with script callbacks. You can use this to connect external services, even websites, to your nwserver in a non-blocking way.
• Also great for linking servers.
• Redis makes for a very good and fast key-value store, with some advanced data structures available. You can even use it as a queue if so desired.

TODO:

• SCO/RCO, so resman can automatically load resources from redis without user intervention. This requires a more generic interface/hook in core.

Hints

• There are two includes, nwnx_redis and nwnx_redis_short. They do the same, but _short is not prefixed with NWNX_Redis.
• nwnx_redis_ps.nss and on_pubsub.nss are not needed if PubSub functionality is not being used.

Setup

• Set up redis-server. Start it. This should be as simple as apt-get install redis. There's also a docker image.
• Configure NWNX_REDIS_HOST and NWNX_REDIS_PORT for nwnx. NWNX_REDIS_PORT is not necessary if the default redis port is used.
• Include the .nss files in NWScript/ into your module.

Accessing Redis from nwscript

To use Redis commands in nwscript include nwnx_redis and nwnx_redis_lib. The nwnx_redis include contains the redis commands like, for example, int NWNX_Redis_GET(string key). All of the nwnx redis comands return an int which is the resultId. The nwnx_redis_lib include contains functions to get the data (and type) you can work with for this resultId. Three of these functions are:

• int NWNX_Redis_GetResultAsInt(int resultId)
• string NWNX_Redis_GetResultAsString(int resultId)
• float NWNX_Redis_GetResultAsFloat(int resultId)

There are also functions to work with result arrays and one to get the type of a result. You can look those up in nwnx_redis_lib.nss.

NWNX_Redis_GetResultAs<Type> has to be called on all the commands that return a resultId even if the actual value is an int as well. The following is an example to set, check for existance of and get a key.

#include "nwnx_redis"
#include "nwnx_redis_lib"
 
NWNX_Redis_SET("examples:examplekey", "testvalue");
if (NWNX_Redis_GetResultAsInt(NWNX_Redis_EXISTS("examples:examplekey")))
{
  string sValue = NWNX_Redis_GetResultAsString(NWNX_Redis_GET("examples:examplekey"));
  WriteTimestampedLogEntry("Value of redis key 'examples:examplekey': " + sValue);
}

Getting started with PubSub

• Create a script called "on_pubsub" (or rename it through NWNX_REDIS_PUBSUB_SCRIPT). An example is included in NWScript/.
• Configure NWNX_REDIS_PUBSUB_CHANNELS to be "test".
• Hint: Subscriptions support wildcards.
• Start your module.
• Use redis-cli to connect to your running redis server and type PUBLISH test hi there.
• Hint: redis-cli monitor in a separate shell is a great way to figure out what's going on.
• Your script should trigger with the payload available through NWNX_Redis_GetPubSubMessageData().

Moving on

• Now think of a good naming scheme for your various pubsub channels. Keep traffic as low as feasible, since each incoming message will trigger a script run. There is no batching yet.
• Hint: By convention, a good namespace separator for channels is "."; for keys ":".
• Example: NWNX_Redis_PUBLISH("nwserver.players.join", GetPCPlayerName(..));
• Hint: A good pattern is to store data in a redis key named after the channel and object identifier (i.e. HSET nwserver:players:PlayerName:.lastSeen 1234) and then trigger a PubSub message with the same subject (PUBLISH nwserver.players.joins PlayerName). This cuts down on wire overhead.

Environment Variables

Variable Name	Type	Default Value
NWNX_REDIS_HOST	string	(none)
NWNX_REDIS_PORT	int16	6379
NWNX_REDIS_PUBSUB_SCRIPT	string	on_pubsub
NWNX_REDIS_PUBSUB_CHANNELS	comma-separated strings	""

Files
file	nwnx_redis.nss
	Autogenerated redis commands for NWNX usage. Autogenerated on: 2019-10-01 20:51:53 -0400.
file	nwnx_redis_lib.nss
	Allows connection and interfacing with a redis server.
file	nwnx_redis_ps.nss
	Interface to Redis PUBSUB.
file	on_pubsub.nss
	Script to handle PubSub event.

Functions
int	NWNX_Redis_GetResultType (int resultId)
	Returns the result type as a int. More...
int	NWNX_Redis_GetArrayLength (int resultId)
	Gets the length of the given result. More...
int	NWNX_Redis_GetArrayElement (int resultId, int idx)
	Gets a list entry as a string. More...
float	NWNX_Redis_GetResultAsFloat (int resultId)
	Gets the given result as a float. More...
int	NWNX_Redis_GetResultAsInt (int resultId)
	Gets the given result as an integer. More...
string	NWNX_Redis_GetResultAsString (int resultId)
	Gets the given result as a string. More...

Function Documentation

NWNX_Redis_GetResultType()

int NWNX_Redis_GetResultType

(

int

resultId

)

Returns the result type as a int.

Definition at line 65 of file nwnx_redis_lib.nss.

NWNX_Redis_GetArrayLength()

int NWNX_Redis_GetArrayLength

(

int

resultId

)

Gets the length of the given result.

Parameters

resultId

The result id.

Returns

The length or 0 if the given result wasn't a list type.

Definition at line 72 of file nwnx_redis_lib.nss.

NWNX_Redis_GetArrayElement()

int NWNX_Redis_GetArrayElement	(	int	resultId,
		int	idx
	)

Gets a list entry as a string.

Parameters

resultId	The result id.
idx	The index in the list.

Returns

The list entry, will return "" if the given result is not a list, or if the requested index is out of bounds.

Definition at line 80 of file nwnx_redis_lib.nss.

NWNX_Redis_GetResultAsFloat()

float NWNX_Redis_GetResultAsFloat

(

int

resultId

)

Gets the given result as a float.

Parameters

resultId

The result id.

Returns

The result as a float.

Definition at line 88 of file nwnx_redis_lib.nss.

NWNX_Redis_GetResultAsInt()

int NWNX_Redis_GetResultAsInt

(

int

resultId

)

Gets the given result as an integer.

Parameters

resultId

The result id.

Returns

The result as an integer.

Definition at line 95 of file nwnx_redis_lib.nss.

NWNX_Redis_GetResultAsString()

string NWNX_Redis_GetResultAsString

(

int

resultId

)

Gets the given result as a string.

Parameters

resultId

The result id.

Returns

The result as a string.

Definition at line 102 of file nwnx_redis_lib.nss.

Variable Documentation

NWNX_REDIS_RESULT_ARRAY

const int NWNX_REDIS_RESULT_ARRAY = 1

Array result.

Definition at line 12 of file nwnx_redis_lib.nss.

NWNX_REDIS_RESULT_ERROR

const int NWNX_REDIS_RESULT_ERROR = 3

Error result.

This never appears: it is rewritten into STRING for simplicity reasons. const int NWNX_REDIS_RESULT_BULK_STRING = 2;

Note

You can retrieve errors as strings.

Definition at line 19 of file nwnx_redis_lib.nss.

NWNX_REDIS_RESULT_INTEGER

const int NWNX_REDIS_RESULT_INTEGER = 4

Integer result.

Warning

This cannot represent integers above 32bit.

Remarks

Use NWNX_Redis_GetResultAsString() if you need the string representation.

Definition at line 24 of file nwnx_redis_lib.nss.

NWNX_REDIS_RESULT_STRING

const int NWNX_REDIS_RESULT_STRING = 5

String result.

Definition at line 27 of file nwnx_redis_lib.nss.

NWNX_REDIS_RESULT_NULL

const int NWNX_REDIS_RESULT_NULL = 6

Null result.

Definition at line 30 of file nwnx_redis_lib.nss.