28 April 2014
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In ColdFusion 11, the WebSocket feature is enhanced further by making it more secure and highly scalable. This article aims to get you familiar with all the new features added to ColdFusion WebSocket to make it an enterprise-ready solution for real-time messaging.
The WebSocket enhancements in ColdFusion 11 can be grouped in three areas. Each area is meant to improve either the security or the scalability of WebSocket.
Here are the three areas of WebSocket enhancements:
ColdFusion uses a dedicated port (8575) to start its internal WebSocket Server and listens to a new client request on it. Earlier, in absence of proxy support, this port was required to be always accessible from outside. This set-up is perfectly fine and works well for intranet application. But for a public facing external application, it’s never advisable to keep a port open and let it be accessible from outside. An unprotected port with no firewall placed between server and the internet, puts the whole server at risk and can easily be attacked. Now, with proxy support added in ColdFusion 11, the WebSocket port is no longer required to be exposed to outside world and rather can be configured safely by hiding it behind the firewall.
In ColdFusion 11, with proxy configured, a client does not require to connect the server directly and rather it can connect to the proxy instead. The proxy will act as an intermediary and receive the WebSocket request from the client on the server behalf and then redirect it to the server. The best part of this proxy framework is that the same connector, which you generally use for serving HTTP request (a CFM template), is extended to accept the WebSocket request too. You just need to configure the connector to handle WebSocket request. The connector can be configured by following a few steps described in this article.
Before we go and configure the proxy, let’s take a look at the following diagram. It shows two strategies of deploying WebSocket Server.
Any one of the following external servers mentioned can be configured as a proxy with the ColdFusion server for WebSocket request.
You can configure an IIS or Apache Server as proxy by performing the following steps.
First step is to enable Websocket protocol to your external server. you need to configure the proxy server as:
IIS server: Please, check this document.
Apache Server: No configuration required.
Perform the following steps:
The external Web Server, usually also called a connector, needs to be attached with the ColdFusion Server using the wsconfig tool. Perform the following steps:
Once the WebSocket Proxy is successfully configured, verify that the required proxy files are created at <CF_INSTALL_HOME>/config/wsproxy/1 and a file called config.ini is present there.
You can manually modify the setting if required. Also, ensure that a new application, cfws, is created under the application root of the external server.
The Set-up is now complete and your proxy is ready to receive and serve WebSocket request at port 80 (or 443 for SSL).
For higher scalability and better performance, it is always advisible to tune the proxy config properties. These properties can be found in config.ini file and are:
Logging needs to be enabled only for debugging purpose. To enable logging at proxy module, open the config.ini and change the EnableLogging to true. And to enable logging at ColdFusion server side change the logging value from warning to debug.
In ColdFusion 11, WebSocket feature is enhanced to support SSL. SSL, as you might know, is a security protocol to help a client to communicate to the server over a secure channel and vice-varsa. Here, a message is first encrypted and then send to the other end for decryption before it can be meaningfully read. SSL provides a mechanism wherein only a client can decrypt the server data and otherway around. A hacker in no way can read or tamper the data being passed and hence minimizes the security risk while transfering the data.
For an enterprise deployment, SSL plays a very important role and become must to have in case you need to host a sensitive application. In ColdFusion 11, a new attribute secure is added to CFWEBSOCKET tag which, if set to true, initiates all the server communications, for this particular client, over a secure socket (SSL). However, before you start using secure attribute, you need to configure various properties like: SSL port, ceritificates, and keystore to ColdFusion Administrator.
You first need to set up the SSL properties in ColdFusion Administrator. The WebSocket admin page (Administrator console > Server Setting > WebSocket) has been enhanced to configure following perperties:
Enable SSL: A checkbox to enable Secure Socket Layer (SSL) for running WebSocket over SSL.
SSL Port: A numeric value for SSL port. WebSocket will listen on this port for any incoming request. Default value is 8543 which can be changed if required.
KeyStore File Location: The location of the keystore in server’s file system. This keystore contains private keys, and the certificates with their corresponding public keys. For instance, the keystore file location is, C:\openSSL\bin\keystore.jks
KeyStore passward: Password to operate the keyStore defined above.
Once the SSL is configured, use the secure attribute of cfwebsocket tag as:
<cfwebsocket name='webSocketObj'onMessage='messageHandler' secure=true />
The secure attribute tells the server to start the WebSocket-client communication in the SSL mode. If the SSL is not enabled in ColdFusion Adminstrator, as shown above, an error will be shown to you to start the SSL first before using secure attribute.
In ColdFusion 11, Cluster support, an another enterprise feature, is added to WebSocket. In multi-instance deployement, where your application runs on various nodes, you would definitely want to keep a client message in sync and get it broadcasted on all the nodes. For instance, when a message is published, rather than just publishing it to the subscribers of that particular node, it should ideally be published to all the subscriber, across the nodes, of the cluster.
For example, Node1 has two clients (C1 and C2) subscribed to the “chat” channel. Similarly Node2 has two clients (C3, C4) and Node3 has two clients (C5, C6) also subscribed to the “chat” channel. Now, when client C1 tries to publish a message on the “chat” channel, rather than just sending this message to C1 and C2 only, the clients from other nodes C3, C4, C5, and C6 must also receive this message.
You first need to enable the WebSocket cluster in ColdFusion Administrator. Under the WebSocket page in the Administrator, look for “Enable WebSocket Cluster” option (see below figure) and check this checkbox if not already checked.
Once the WebSocker cluster is enabled, make sure that the “Multicast Port” is also defined. It mostly comes configured as 45566 and you don’t need to change it unless this port is not free and being used by some other system. The port is used to broadcast node up/down events. When a node comes up, it needs to intimate its peer about its coming live and joining the cluster. Similarly, when a node is going down, it will first notify its peers about the same before it really become unaccessible.
It is important to note that the cluster feature is avaible only in the Enterprise edition of ColdFusion 11. If you are having a standard edition and want to use Cluster then you have to first upgrade your ColdFusion server before you can avail the Cluster functionality.
ColdFusion also provides some in-built function to broadcast a WebSocket message to its subscriber. The following functions are enhanced to auto-support cluster functionality.
wsPublish(“channel name”, messageBody [, cluster]) wsGetSubscriber(“channel name” [, cluster] ) wsGetAllChannels(“channel name”[, cluster]);
The goal of this article is to provide a general overview of various WebSocket enterprise features added to the latest version of ColdFusion and thus helping you to use IIS or Apache as proxy to safeguard and protect your underlying WebSocket Server from external attack. It will be nice if you try configuring an IIS or Apache Server at your end to get better understanding on how a WebSocket proxy works. Same is true for SSL and Cluster support also. A basic article on WebSocket is available here. See the ColdFusion 11 documentation for more details on the latest WebSocket features.