Awesome
MemGator
A Memento Aggregator CLI and Server in Go.
Features
- The binary (available for various platforms) can be used as the CLI or run as a Web Service
- Results available in three formats - Link/JSON/CDXJ
- TimeMap, TimeGate, and Memento (redirect or description) endpoints
- Optional streaming of benchmarks over Server-Sent Events (SSE) for realtime visualization and monitoring
- Good API parity with the main Memento Aggregator service
- Concurrent - Splits every session in subtasks for parallel execution
- Parallel - Utilizes all the available CPUs
- Custom archive list (a local JSON file or a remote URL) - A sample JSON is included in the repository
- Probability based archive prioritization and limit
- Configurable automated temporary exclusion of malfunctioning upstream archives
- Three levels of customizable timeouts for greater control over remote requests
- Customizable logging and profiling in CDXJ format
- Customizable endpoint URLs - Helpful in load-balancing
- Customizable User-Agent to be sent to each archive and User-Agent spoofing
- Configurable archive failure detection and automatic hibernation
- CORS support to make it easy to use it from JavaScript clients
- Memento count exposed in the header that can be retrieved via
HEAD
request - Docker friendly - An image available as oduwsdl/memgator
- Sensible defaults - Batteries included, but replaceable
Usage
CLI
Command line interface of MemGator allows retrieval of the TimeMap and the description of the closest Memento (equivalent to the TimeGate) over STDOUT
in all supported formats. Logs and benchmarks (in verbose mode) and Error output are available on STDERR
unless appropriate files are configured. For further details, see the full usage.
$ memgator [options] {URI-R} # TimeMap from CLI
$ memgator [options] {URI-R} {YYYY[MM[DD[hh[mm[ss]]]]]} # Description of the closest Memento from CLI
Server
When run as a Web Service, MemGator exposes following customizable endpoints:
$ memgator [options] server
TimeMap: http://localhost:1208/timemap/{FORMAT}/{URI-R}
TimeGate: http://localhost:1208/timegate/{URI-R} [Accept-Datetime]
Memento: http://localhost:1208/memento[/{FORMAT}|proxy]/{DATETIME}/{URI-R}
About: http://localhost:1208/about
Monitor: http://localhost:1208/monitor - (Over SSE, if enabled)
{FORMAT} => link|json|cdxj
{DATETIME} => YYYY[MM[DD[hh[mm[ss]]]]]
[Accept-Datetime] => Header in RFC1123 format
TimeMap
endpoint serves an aggregated TimeMap for a given URI-R in accordance with the Memento RFC. Additionally, it makes sure that the Mementos are chronologically ordered. It also provides the TimeMap data serialized in additional experimental formats.TimeGate
endpoint allows datetime negotiation via theAccept-Datetime
header in accordance with the Memento RFC. A successful response redirects to the closes Memento (to the given datetime) using theLocation
header. The default datetime is the current time. A successful response also includes aLink
header which provides links to the first, last, next, and previous Mementos.Memento
endpoint allows datetime negotiation in the request URL itself for clients that cannot easily send custom request headers (as opposed to theTimeGate
which requires theAccept-Datetime
header). This endpoint behaves differently based on whether theformat
was specified in the request. It essentially splits the functionality of theTimeGate
endpoint as follows:- If a format is specified, it returns the description of the closest Memento (to the given datetime) in the specified format. It is essentially the same data that is available in the
Link
header of theTimeGate
response, but as the payload in the format requested by the client. - If a format is not specified, it redirects to the closest Memento (to the given datetime) using the
Location
header. - If the term
proxy
is used instead of a format then it acts like a proxy for the closest original unmodified Memento with added CORS headers.
- If a format is specified, it returns the description of the closest Memento (to the given datetime) in the specified format. It is essentially the same data that is available in the
About
endpoint reports the list of upstream archives, their status, and values of various configurations of the server.Monitor
is an optional endpoint that can be enabled by the--monitor
flag when the server is started. If enabled, it provides a stream of the benchmark log over SSE for realtime visualization and monitoring.
NOTE: A fallback endpoint /api
is added for compatibility with Time Travel APIs to allow drop-in replacement in existing tools. This endpoint is an alias to the /memento
endpoint that returns the description of a Memento.
Download and Install
Depending on the machine and operating system download appropriate binary from the releases page. Change the mode of the file to executable chmod +x MemGator-BINARY
. Run from the current location of the downloaded binary or rename it to memgator
and move it into a directory that is in the PATH
(such as /usr/local/bin/
) to make it available as a command.
Running as a Docker Container
Build a Docker image locally from the source.
$ git clone https://github.com/oduwsdl/MemGator.git
$ cd MemGator
$ docker image build -t oduwsdl/memgator .
Alternatively, pull a published image from one of the two Docker image registries below:
$ docker image pull docker.pkg.github.com/oduwsdl/memgator/memgator
$ docker image pull oduwsdl/memgator
Run MemGator with various options inside a Docker container.
$ docker container run -it --rm oduwsdl/memgator -h
$ docker container run -it --rm oduwsdl/memgator [options] {URI-R}
$ docker container run -it --rm oduwsdl/memgator [options] {URI-R} {YYYY[MM[DD[hh[mm[ss]]]]]}
$ docker container run -d --name=memgator-server -p 1208:1208 oduwsdl/memgator [options] server
$ curl -i http://localhost:1208/about
$ docker container rm -f memgator-server
Full Usage
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/ \ _____ _____ / _____/______/ |___________
/ Y Y \/ __ \/ \/ \ ___\__ \ _/ _ \_ _ \
/ | | \ ___/ Y Y \ \_\ \/ __ | | |_| | | \/
\__/___\__/\____\__|_|__/\_______/_____|__|\___/|__|
# MemGator ({Version})
A Memento Aggregator CLI and Server in Go
Usage:
memgator [options] {URI-R} # TimeMap from CLI
memgator [options] {URI-R} {YYYY[MM[DD[hh[mm[ss]]]]]} # Description of the closest Memento from CLI
memgator [options] server # Run as a Web Service
Options:
-A, --agent=MemGator/{Version} <{CONTACT}> User-agent string sent to archives
-a, --arcs=https://git.io/archives Local/remote JSON file path/URL for list of archives
-b, --benchmark= Benchmark file location - defaults to Logfile
-c, --contact=https://git.io/MemGator Comment/Email/URL/Handle - used in the user-agent
-D, --static= Directory path to serve static assets from
-d, --dormant=15m0s Dormant period after consecutive failures
-F, --tolerance=-1 Failure tolerance limit for each archive
-f, --format=Link Output format - Link/JSON/CDXJ
-H, --host=localhost Host name - only used in web service mode
-k, --topk=-1 Aggregate only top k archives based on probability
-l, --log= Log file location - defaults to STDERR
-m, --monitor=false Benchmark monitoring via SSE
-P, --proxy=http://{HOST}[:{PORT}]{ROOT} Proxy URL - defaults to host, port, and root
-p, --port=1208 Port number - only used in web service mode
-R, --root=/ Service root path prefix
-r, --restimeout=1m0s Response timeout for each archive
-S, --spoof=false Spoof each request with a random user-agent
-T, --hdrtimeout=30s Header timeout for each archive
-t, --contimeout=5s Connection timeout for each archive
-V, --verbose=false Show Info and Profiling messages on STDERR
-v, --version=false Show name and version
Build
Assuming that Git and Go (version >= 1.14) are installed. Cloning, running, building, and installing the code can be done using following commands:
$ git clone https://github.com/oduwsdl/MemGator.git
$ cd MemGator
$ go run main.go
$ go build
$ go install
$ memgator --help
$ memgator http://example.com/
To compile cross-platform binaries run the crossbuild.sh
script:
$ ./crossbuild.sh
This will generate binaries for various OSes and Architectures in /tmp/mgbins
directory.
Citing Project
A publication related to this project appeared in the proceedings of JCDL 2016 (Read the PDF). Please cite it as below:
Sawood Alam and Michael L. Nelson. MemGator - A Portable Concurrent Memento Aggregator: Cross-Platform CLI and Server Binaries in Go. In Proceedings of the 16th ACM/IEEE-CS on Joint Conference on Digital Libraries, JCDL 2016, pp. 243-244, Newark, New Jersey, USA, June 2016.
@inproceedings{jcdl-2016:alam:memgator,
author = {Sawood Alam and
Michael L. Nelson},
title = {{MemGator - A Portable Concurrent Memento Aggregator}},
booktitle = {Proceedings of the 16th ACM/IEEE-CS Joint Conference on Digital Libraries},
series = {JCDL '16},
year = {2016},
month = {jun},
location = {Newark, New Jersey, USA},
pages = {243--244},
numpages = {2},
url = {http://dx.doi.org/10.1145/2910896.2925452},
doi = {10.1145/2910896.2925452},
isbn = {978-1-4503-4229-2},
publisher = {ACM},
address = {New York, NY, USA}
}