The JSON archive proxy for Control System Studio is a simple tool that can be used in combination with any archive reader for CSS in order to simplify the archive configuration.
The archive proxy consists of two components: The JSON archive server can expose any archive reader via a simple protocol based on HTTP and JSON. The JSON archive reader in turn connects to an instance of the JSON archive server and makes its archives available in CSS.
The JSON archive proxy offers two advantages over a direct use of an archive reader in CSS. First, the reader is light-weight and does not depend on the structure of the database actually storing the data. Thus the archive implementation can be upgraded (including changes in the database structure) without having to update all instances of CSS that access the archive. It is sufficient to update the archive reader plugins installed in the JSON archive server. Second, the JSON archive proxy can be used in environments where the database servers are behind a firewall and direct access to the databases is not desired for security considerations. With the JSON archive proxy, the JSON archive server is installed in the same network that is accomodating the database servers (the archive server can even run on the same machine as the database server) and only a single port has to be opened for allowing the communication between archive server and reader. As the protocol is based on HTTP, a HTTP reverse proxy can be used for adding extra security layers (e.g. SSL).
Since version 3.x, the JSON Archive Proxy components are distributed through a P2 repository (Eclipse update site). You can find the URL of the P2 repository for the respective version in the Download section.
Please refer to the documentation of the respective release for detailed installation instructions.
Using the JSON archive proxy is very simple. It is enough to copy the JSON archive reader plugin to the CSS distribution's plugins directory and copying the plugins of the underlying archive reader (e.g. for the Cassandra Archiver or RDB Archiver) to the plugins directory of the JSON archive server.
More detailed instructions can be found in the README.txt file in the binary distribution of the JSON archive proxy.
This program and the accompanying materials are made available under the terms of the Eclipse Public License v1.0. By downloading the software you agree to be bound the the terms of this license. In particular, you have to agree to sections five (“NO WARRANTY”) and six (“DISCLAIMER OF LIABILITY”) before downloading the software.
Some files in the binary distribution have different copyrights and licenses. Refer to the information provided in the package for details about those copyrights and licenses.
Release 3.0.0 (March 28th, 2017):
This release of the JSON Archive proxy adds compatibility with CSS 4.3 and 4.4. It is not compatible with older versions of CSS. The protocol has not changed, so this release is still compatible with all earlier versions.
Starting with this release, there is no archive download any longer. Instead, the software is provided through a P2 repository (Eclipse update site).
Release 2.0.3 (July 25th, 2016):
This release of the JSON archive proxy fixes a problem that caused the precision information of samples to be lost, resulting in only in the integer part of floating-point samples being shown. correctly in the CSS Data Browser. This release should be compatible with CSS 3.2, 4.0, and 4.1. It does not make any changes to the server component and thus the server version contained in the archive remains at version 2.0.1. The protocol has not changed, so this release is still compatible with all earlier versions.
Release 2.0.2 (June 2nd, 2016):
This release of the JSON archive proxy fixes a problem that caused samples with statistics information (minimum and maximum value) not to be displayed correctly in the CSS Data Browser. This issue was caused by the samples not implementing an interface that was expected by the Data Browser code. This release should be compatible with CSS 3.2, 4.0, and 4.1. It does not make any changes to the server component and thus the server version contained in the archive remains at version 2.0.1. The protocol has not changed, so this release is still compatible with all earlier versions.
Release 2.0.1 (August 27th, 2015):
This release of the JSON archive proxy fixes compatibility issues with CSS 4.1. It should be compatible with CSS 3.2, 4.0, and 4.1. It also fixes a bug in the server component that caused most requests for samples to fail. The reader component was not affected by this bug. The protocol has not changed, so it is still compatible with versions 1.0.0 and 2.0.0.
Release 2.0.0 (July 14th, 2014):
This release of the JSON archive proxy uses the new PVManager API introduced with CSS 3.2 instead of the old PV abstraction layer. The JSON protocol is the same as for version 1.0 of the JSON archive proxy, thus a 2.0 client (archive-reader plugin) can connect to a 1.0 server and vice-versa. This way, old archive-reader plugins can be used with new versions of CSS and old versions of CSS can use new archive-reader plugins.
Release 1.0.0 (Feburary 23rd, 2013):
This is the first release of the JSON archive proxy. This release is designed to work with CSS 3.1. For CSS 3.2 you have to use version 2.0.
You can contact the author of this software, Sebastian Marsching, at json-archive-proxy-maintainer<at> oss <dot> aquenos <dot> com.
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