- Navigation links to switch between the main View Messages tab and the Documentation tab.
- A status-summary for Clients that MQ Light knows about. Disconnected Clients are those that at one point were connected, then went away. Using “Clear History” will clear out the Disconnected count (among other things).
- The View Messages tab gives a live view of what’s connected to, and flowing through MQ Light. It also retains some historic data whilst left open, such as delivered Messages, disconnected Clients, and counts of messages sent/received. This historic data can be cleared at any time with the “Clear History” link. A timer is also provided, to give context to the sent/received counts.
- Username/password security can be set when you start MQ Light for the first time (and settings can be changed later via the
mqlight-configcommand). The icon in this screenshot (an open padlock) shows that security is disabled.
- The Sending section contains information about Clients sending messages via MQ Light. Note that the same Client could appear as both Sending and Receiving, if it’s performing both actions! In this screenshot, there are six Clients that have sent messages.
- Front and centre in this panel are the messages themselves. Each message appears by default, with the time it was sent, a preview of its content, and an overview of its status.
Opening up the Details section for a message displays further information such as the Topic it was sent on (Topic is compared against a Destination’s Topic Pattern, and if they match, the message is delivered – as such, Topics control who gets what messages). You will also see a list of the Destinations – if there was an error, you can identify which Destination failed to get the message.
In this screenshot, filters have been applied to the Messages panel, and therefore there is a cross icon here used to remove the filters.
- Every message has a Topic, which controls who it is received by, by matching against a Topic Pattern. Use this filter to control the content of the Messages panel by Topic Pattern.
- The Receiving section shows Destinations that have received messages through MQ Light. Note that the same Client could appear as both Sending and Receiving if it’s performing both actions! Some Destinations are individual Clients, and others are Shares. In a Share, messages could be delivered to any of the member Clients – they are a good way of achieving the worker offload pattern. Each Destination has a Topic Pattern, which defines the type of messages it is interested in.
The screenshot shows a mixture of Private and Shared Destinations.
- Clicking Sender tiles like these, or the equivalent Receiver tiles will filter the messages displayed in the central panel. For example, clicking a sender would filter the messages to show only those sent by that particular client. The speech bubble icon on each sending Client labels the count of messages that the Client has sent.
- These buttons toggle the behaviour options of the Messages panel. The left button switches between showing (default) or hiding delivered messages (useful if you want to concentrate just on the messages that have not yet been fully delivered). In the screenshot, delivered messages are shown. The play/pause button switches between automatically loading in all new messages (default) and batching them up to be loaded in to the UI when you want (useful if you want to look at a specific message without it scrolling down the view). In the screenshot, new messages are automatically loaded.
- This icon labels a summary of how many Destinations have successfully received the message.
- Receiving Destinations display a count of messages they’ve received next to this speech bubble icon. Also shown is the Topic Pattern for this Destination. This Destination in the screenshot is highlighted because it has been clicked to filter the messages in the centre (to only show ones that this Destination has received).
- This is a Share, so additional information is available – this icon indicates the number of members (Clients) in the Share. Also shown is the share name and the status of each of the member Clients. Similar to Private Destinations, Shares display their Topic Pattern and number of messages received.
The following icons are used on the MQ Light User Interface, to represent different objects, such as sending and receiving clients, message delivery status, and security settings. MQ Light alters the icons slightly to indicate the status of the objects, for example, connected or disconnected: