How to build an open source WebGIS System

How can we build our own WebGIS system? Do you need to spend a lot of money to buy other people's money or do it yourself? I think this should be taken into consideration based on your actual situation. If you are rich and willing to spend money, I can't help it. But if you want me to be the same, have no money, but have a deep passion for GIS, then do your open source WebGIS system.

spatial database : PostgreSQL/postgis is used. Use PostgreSQL 8.0 Win32 on Windows platform, which can be obtained from www.postgresql.org. This version already contains postgis. You must select the postgis option during installation. Postgis implements the OpenGIS Simple Feature Specification and provides spatial indexes. Postgis official site: http://postgis.refractions.net /.
GIS middleware : geotools is a mature open-source GIS middleware with a history of nearly 10 years, there is also an official OpenGIS background. You can obtain it from www.geotools.org. Geotools is implemented in Java with excellent architecture and easy extension. Geotools uses another famous open-source software JTs (Java topology suite ). JTs encapsulates common geo algorithms , implements simple feature specifications of OpenGIS, and provides memory-based spatial indexes.
Web Map server : geoserver is used. Download from http://geoserver.sourceforge.net. Geoserver implements the OpenGIS WMS specification and WFS specification. Or deegree. The entire deegree system is fully based on OGC specifications and concepts. It provides OGC services such as WMS and WFS. Deegree official website address: http://deegree.sourceforge.net/
GIS Editor : using another famous GIS Open Source Software jump. Download from http://www.jump-project.org. Based on Java, jump adopts plug-in mechanism and is easy to expand. Another website http://jump-pilot.sourceforge.net/has jumpplug.
browser client : it can be implemented using JavaScript, Flash, or Java applet.