Changeset 547 in ntrip for trunk

Timestamp:

Oct 23, 2007, 12:54:01 PM (17 years ago)

Author:

stuerze

Message:

source table filter description added

File:

• trunk/ntripclient/README (modified) (3 diffs)

trunk/ntripclient/README

@@ -33 +33 @@
 of RTCM via Internet Protocol' (Ntrip). This is an application-level 
 protocol streaming Global Navigation Satellite System (GNSS) data over 
-the Internet. Ntrip is a generic, stateless protocol based on the 
-Hypertext Transfer Protocol HTTP/1.1. The HTTP objects are enhanced 
-to GNSS data streams.
+the Internet. Ntrip Version 1.0 is a generic, stateless protocol based 
+on the Hypertext Transfer Protocol HTTP/1.1. The HTTP objects are 
+enhanced to GNSS data streams.
+
+The primary motivation for Ntrip Version 2.0 is to develop a fully 
+HTTP-compatible Internet protocol standard that would work with proxy 
+servers and to add an optional data transport via UDP. Hence, one 
+Ntrip Version 2.0 transport approach is still based on HTTP1.1 on top 
+of TCP. The second Ntrip Version 2.0 transport approach is based on 
+both, the Internet Standard Protocol RTSP (Real Time Streaming Protocol) 
+for stream control on top of TCP and the Internet Standard Protocol RTP 
+(Real Time Transport Protocol) for data transport on top of 
+connectionless UDP.
 
 Ntrip is designed for disseminating differential correction data 
@@ -62 +72 @@
 
 ntripclient -s server -u user ...
- -d --data      the requested data set
+ -d --data      the requested data set or criteria for sourcetable filtering
  -s --server    the server name or address
  -p --password  the login password
@@ -83 +93 @@
 The argument '-h' will cause a HELP on the screen.
 Without any argument ntripclient will provide the a table of
-available resources (source table).
+available resources (sourcetable).
+
+Sourcetable filtering
+----------------------
+A missing argument '-d' leads to the output of the complete broadcaster
+sourcetable. This may comprise hundreds of lines in case of large 
+networks. To limit the output, the sourcetable contents can be filtered 
+through entering the argument '-d' followed by a sequence of query strings,
+one for each sourcetable data field. Only those sourcetable lines are
+returned from the broadcaster whoes data fields match the corresponding
+query strings. A sequence of query strings has to be initiated by a '?'
+and a semicolon is acting as query string delimiter in analogy to the
+sourcetable data field delimiter.
+
+Note that for fully understanding the sourcetable filtering option
+you have to make yourself familiar with the details of the sourcetable
+contents. In general, search criterias can be applied on each sourcetable 
+data field.
+
+The following query string operators are available for integer and
+floating-point numbers in the sourcetable lines:
+
+- Equation operators: <, >, >=, <=, =, != (not equal)
+- Approximation operator: ~n (find value with minimal distance to n)
+
+The following query string operators are available for alphanumeric
+strings in the sourcetable lines:
+
+- Wildcard operator: '*' means any number of characters
+- Alternation operator: expression|expression
+- Grouping operator: (expression)
+- Any character matching for strings (case insensitivity)
+
+The following operators are available for both text as well as integer
+and floating-point numbers in the sourcetable lines:
+
+- Logical operators: ! (NOT), & (AND), | (OR)
+- Grouping operator: [!] (Expression)
+
+Examples:
+
+- Searching in a sourcetable for streams in Germany would require
+  entering the '-d' argument followed by
+  the query string:
+  ?STR;;;;;;DEU
+
+- Searching in a sourcetable for free streams fom the EUREF network and
+  coming from the Frankfurt area would require entering the '-d' argument
+  followed by the query string:
+  ?STR;;;;;;;EUREF;;=>50&<=51;=>8.1&<8.6;;;;;N
 
 Compilation/Installation