nsq-topics

Nsq helper to poll a nsqlookupd service for all it's topics and mirror it locally.

INFO: all examples are written in coffee-script

Install

  npm install nsq-topics

Initialize

new NsqTopics( config );

Example:

var NsqTopics = require( "nsq-topics" )

var topics = new NsqTopics({
    // Listen to two local nsq lookupservers
    "lookupdHTTPAddresses": [ "127.0.0.1:4161", "127.0.0.1:4163" ]
});

// get the current list of topics
topics.list( function( err, topics ){
    if( err ){
        // handle the error
    }
    console.log( topics ) // -> an array of topics. E.g.: ( )`users`, `logins`, ... )


    // listen for new topics
    topics.on( "add", function( topic ){
        // called until a new topic arrived
    });

    // listen for removed topics
    topics.on( "remove", function( topic ){
        // called until a topic was removed
    });

    // listen for topic list changes
    topics.on( "change", function( topicList ){
        // beside the `add` and `remove` events a single "change" event will be emitted
    });

    // setting a filter to only listen to specific topics
    topics.filter( [ "user", "logins", "posts" ] );

    // listen for errors
    topics.on( "error", function( err ){
        // E.g. called if a invalid filter was used or no lookup server is available
    });

});

Config

• lookupdHTTPAddresses : ( String|String[] required ) A single or multiple nsqlookupd hosts. This is also a configuration of 'nsqjs'
• lookupdPollInterval : ( Number optional: default = 60 ) Time in seconds to poll the nsqlookupd servers to sync the available topics. This is also a configuration of 'nsqjs'
• topicFilter : ( Null|String|Array|RegExp|Function optional: default = null ) A filter to reduce the returned topics
• active : ( Boolean optional: default = true ) Configuration to (de)activate the nsq topics on startup

Methods

.activate()

Activate the module

Return

( Boolean ): true if it is now activated. false if it was already active

.deactivate()

Deactivate the module

Return

( Boolean ): true if it is now deactivated. false if it was already inactive

.active()

Test if the module is currently active

Return

( Boolean ): Is active?

.list( cb )

Get a list of the current topics

• cb : ( Function optional ): Callback to get the list of topics

Return

( Self ): The instance itself for chaining.

Example:

topics.list( function( err, topics ){
    if( err ){
        // handle the error
    }
    console.log( topics ) // -> an array of topics. E.g.: ( )`users`, `logins`, ... )
});

Events

add

A new topic was added

Arguments

• topic : ( String ) The new topic

Example:

topics.on( "add", function( topic ){
    // called until a new topic arrived
});

remove

A existing topic was removed

Arguments

• topic : ( String ) The removed topic

Example:

topics.on( "remove", function( topic ){
    // called until a topic was removed
});

change

The list of topics changed

Arguments

• topics : ( String[] ) A list of current topics

Example:

topics.on( "change", function( topicList ){
    // beside the `add` and `remove` events a single "change" event will be emitted
});

error

An error occurred. E.g. called if a invalid filter was used or no lookup server is available

Arguments

• err : ( Error ) The error object.

Example:

topics.on( "error", function( err ){
    // handle the error
});

ready

Emitted once the list of topics where received the first time. This is just an internal helper. The Method list will also wait for the first response. The events add, remove and change are active after this first response. Example:

topics.on( "ready", function( err ){
    // handle the error
});

Release History

Version	Date	Description
1.1.0	2019-01-25	now able to handle the formats of nsq < and > 1.x
1.0.0	2019-01-25	updated topic response handler to match nsq >= 1.x format
0.0.6	2018-11-17	Updated dependencies
0.0.5	2016-07-18	Updated dependencies and removed generated code docs from repo
0.0.4	2016-05-09	Updated dependencies. Especially lodash to 4.x
0.0.3	2016-02-19	Fixed default configuration
0.0.2	2015-11-30	Bugfixes; Tests; Docs
0.0.1	2015-11-27	Initial commit

Initially Generated with generator-mpnodemodule

Other projects

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nsq-nodes	Nsq helper to poll a nsqlookupd service for all it's nodes and mirror it locally.
nsq-watch	Watch one or many topics for unprocessed messages.
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The MIT License (MIT)

Copyright © 2015 M. Peter, http://www.tcs.de

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.