JSAMP is a Java-based implementation of the Simple Application Messaging Protocol (SAMP), an official standard managed by the International Virtual Observatory Alliance (IVOA). It serves as the middleware layer that enables disparate desktop and web-based astronomy tools to communicate, exchange data, and share control in real time.
Rather than bundling massive, redundant capabilities into a single software application, JSAMP allows astronomers to link highly specialized tools into a single, cohesive workflow. Core Architecture & How it Works
The JSAMP ecosystem operates on a Hub-and-Spoke network topology:
The Hub: A central broker application (frequently provided directly by JSAMP). It manages registrations, tracks active applications, and routes messages.
The Clients: Individual astronomical tools (e.g., Aladin, TOPCAT, DS9) that register with the Hub to listen for or broadcast specific data types.
The Profiles: Underlying transport protocols. While desktop tools use the Standard Profile (XML-RPC over TCP/IP), JSAMP also provides a Web Profile. This allows web browsers to securely pass data straight to desktop tools. Typical Connected Tools in an Ecosystem
A standard tutorial or workflow leveraging JSAMP typically links these popular Virtual Observatory (VO) applications:
TOPCAT: Used for analyzing, filtering, and manipulating large tables and catalogs of stellar objects.
Aladin Lite / Aladin Desktop: An interactive sky atlas utilized for visual mapping and overlaying images.
SAO DS9: A specialized data visualization application tailored for viewing FITS images and x-ray/infrared arrays. Step-by-Step Practical Workflow Tutorial
This baseline guide illustrates how JSAMP connects multiple tools to analyze an astronomical target seamlessly: 1. Initialize the Hub
Launch the JSAMP Hub. In many setups, starting TOPCAT automatically triggers a background SAMP hub. Alternatively, you can spin it up via the command line or embed it in Astropy Python workflows: java -jar jsamp.jar hub Use code with caution. 2. Establish Tool Registration
Open your preferred desktop applications (e.g., Aladin and DS9). Upon opening, these programs automatically seek out the active JSAMP Hub and register as listening clients. You will visually see their respective icons connect inside the Hub interface. 3. Broadcast Data Interactively
Table Broadcast: Within TOPCAT, load a large catalog table of stars. Click the SAMP Broadcast button to instantly replicate that table across to Aladin.
Visual Synchronization: Select or click a specific star row inside your TOPCAT table. Through JSAMP, a precise highlight event is triggered, causing Aladin’s sky camera view to automatically center on that exact target’s celestial coordinates (
FITS Transmission: Trigger an image load command from a browser archive or TOPCAT. JSAMP pipes the raw FITS data file directly into SAO DS9 for physical pixels and histogram analysis. Common Messaging Types (MTypes)
JSAMP relies on pre-defined message templates called MTypes so disparate programs know how to process incoming files. The foundational types include:
table.load.votable: Delivers a Virtual Observatory XML table file.
image.load.fits: Transmits a Flexible Image Transport System image layer.
coord.point.at: Prompts sky viewers to automatically center coordinates on a targeted object.
client.highlight.row: Highlights an exact row or data point matching an event triggered in another client tool.
samp to send an image directly to DS9? Alternatively, I can help you troubleshoot connection errors between your desktop tools. SAMP (Simple Application Messaging Protocol) (astropy.samp)
Leave a Reply