MEAN stack and IOT are the current trending hot topics. Can these two be used together? If yes then in what way?
How can these technologies be used together?
Sweta.
By saying MEAN.js you are including things that are not strictly in the IoT terrain. Angular for example has little to do with anything.
On the web front end you need to implement a javascript library like Paho.js that will use the MQTT protocol to connect to a broker and start aggregating messages from connected devices.
Express has little to do as well as you are not exposing a Restful interface but connecting low level through a broker. A good solution in Node.js is Mosca.
Mongo is good for dumping data from devices.
I have written a tutorial using Node.js and iOS so have a look and you might find it interesting.
Mean stack is the combination of the frontent web frameworks like angularjs,emberjs,knockoutjs,backbonejs , javascript's backend server called nodejs and using the mongodb at top. so using these frameworks and library will make a mean stack developer.
IoT pronounced as Internet of things. iot is recently used for connected electronics devices .basically it is a form of running your program inside the electronic chip and mostly trying to connect the devices.making control on devices using the programmed chip. there are separate IDE's are avaialble for developing and testing the programme on embeded chip.
you can use angularjs as a frontend(making your GUI) for your IoT'S application.
Yes, you can.
As a fact is has been done before. And in other frontend frameworks too. Here there is an example for home automation.
You can find even a yeoman generator for such projects here.
[Disclaimer: I work here] Netbeast started managing devices and creating a system of plugins on top
of a MEAN app and RESTful communications. (Now we use a MERN
stack, with react and MQTT over websockets to control networks and
update values in real time.)
To mention other places where you can find examples of current projects using MEAN to run IoT networks I encourage you to join angular, arduino and raspberry communities, as well as taking a tour over producthunt.com, hackster.io and other maker sites such as the previously mentioned Netbeast forum.
Yes you can make an IoT platform with the MEAN stack. Typically the sensors are low cost sensors and are constantly transmitting small amounts of data in MQTT or TCP protocols. With Node.js you can write, servers for such applications very easily.
Mongo is useful if you have unstructured data, which could happen if you work with multiple sensors. If you don't need unstructured data structures, SQL is sufficient.
All the data that you get from devices, finally needs to be consumed via applications. Express and Angular are great platforms to manage web applications.
You can read a little more about IoT platforms in MEAN at http://blog.yatis.io/scalable-iot-platform-mean-stack/
Related
I have been reading the abstracts on the website http://www.rikulo.org but all those cryptic vague statements do not help me. The examples are all about visuals.
I do not understand what this framework is capeable of doing. The big picture is missing.
What kind of apps can i build with rikulo?
Is there any access to the hardware?
Can is use the smartphones sensordata and send e.g. coordinates from my smartphone to a web service?
What are the limitations?
As described in this blog, Rikulo is aimed to provide a structured UI model for Web and mobile programming. We are the same team who developed ZK. With Rikulo, we'd like to take a step further since many things have been changed since we developed ZK in 2005. Also, both Dart and HTML 5 are young. It is an excellent moment to explore the best possible UI architecture for both Web and mobile programming.
For example, we use absolute positioning to give programmers 100% control the layout of UI rather than spending hours to figure out why it fails in certain combination. Another example is "recursive layered structure", such as layout manager and visual effect handling -- rather than ad hoc features targeting specific problems individually.
On the other hand, we don't have many widgets yet. It might be the reason that confused you. As a Apache licensed project, we hope we can have an active community for building widgets and addons, as long as we can really provide a solid and elegant architecture -- it is what we focus now and keep refining.
To access the hardware, you can use Rikulo Gap which is based on Cordova/PhoneGap. To communicate back the server, you can use Web socket or HttpRequest. We will have more advanced support for jsonizing, caching and communicating Dart objects between client and server, but it is not ready yet.
Technically, there is no limitation. Of course, the current number of widgets is definitely not enough, but it will get more in the near future. Furthermore, you always can create them with HTML 5 (and contribute back). However, for mobile applications, one thing you have to keep in mind: the performance won't be as good as the apps written in Objective C. The good is Rikulo is cross platform and your app can be accessed with Web browsers and as a native app.
I want to know what is the difference between these two implementations of neo4j. Of-course names of both techniques is self-explanatory,but still what are the main differences?
What factors should be considered in deciding which technique to use in the project?
Pros and cons.
P.S. Sorry if it is a repeat question but I searched and was not able to find any ques which answers my question.
Because the standalone server is built on the embedded server, the general rule of thumb is that the embedded server is more capable and has (obviously) lower latency. Either can operate in High-Availability mode, allow monitoring, and even accept connections from the neo4j-shell. With the server though, you get more functionality out-of-the-box, like remoting, basic visualization, monitoring interface, etc.
The differences are otherwise the practical ones you'd imagine. Choosing a deployment approach is influenced by two things:
Language - embedded mode requires that you're implementing your application with a JVM compatible language. The server supports any language/framework that can send HTTP requests.
Hardware - sharing physical resources between your application and Neo4j can be demanding. Scaling may argue for a dedicated machine to split out the persistence layer. The server obviously has a remote API to support segmenting your application.
It's otherwise difficult to give guidance without a specific usage scenario. Deploying into an existing Service Oriented Architecture? Probably server. Running on an copier machine? Go embedded. From scratch web application? What's the rest of your stack?
I am currently learning Erlang
Can SO users give interesting examples of any of their Erlang application deployments?
I want to gain some insight into common Erlang uses past telecomms, and any problems or unexpected benefits Erlang brought during development/deployment.
I hope this will give some broader context and whet the whistle for myself and anyone else jumping into Erlang!
Thanks in advance!
Who uses Erlang for product development:
Bluetail/Alteon/Nortel (distributed,
fault tolerant email system, SSL
accelerator)
Cellpoint (Location-based Mobile
Services)
Corelatus (SS7 monitoring).
dqdp.net (in Latvian) (Web Services).
Facebook (Facebook chat backend)
Finnish Meteorological Institute
(Data acquisition and real-time
monitoring)
IDT corp. (Real-time least-cost
routing expert systems)
Klarna (Electronic payment systems)
Mobilearts (GSM and UMTS services)
Netkit Solutions (Network Equipment
Monitoring and Operations Support
Systems)
Process-one (Jabber Messaging)
Schlund + Partner (Messaging and
Interactive Voice Response services)
Quviq (Software Test Tool)
RabbitMQ (AMQP Enterprise Messaging)
T-Mobile (previously one2one)
(advanced call control services)
Telia (a telecomms operator)
Vail Systems (Interactive Voice
Response systems)
Wavenet (SS7 and IVR applications)
Our first application was a web/sms social network and I wrote a long paper on the subject which can be read here.
We've built a web app based on an Erlang backend.
Erlang is in charge of the business logic, the security and data store.
The browser communicates exclusively through JSON services with it and do the rendering.
It will be in beta soon, and to give you an idea of the app there is a video here
There are as well some resources here and here about what we learned along the way.
Get to know the the release tools erlang/OTP already provides.
Erlang bootscripts are wonderful for ensuring that all the running applications needed are present and of the correct version. Working within the OTP framework for releases will be much easier than trying to invent your own. Erlang has lots of tools for making sure deployments can be done both live and without breaking running services. The language and runtime are designed for this so they've done a lot of the heavy lifting for you. I've found the tools useful even for small "non-enterprise" apps and deployments.
Of course there's always applications like wings3D which is for 3D modelling. It's not exactly a "deployment", because these sorts of programs are used anywhere from individuals to teams of artists in their pipeline. There are other projects for things like simulation, but I'm not sure how many companies are publicly stating that they use Erlang. As for me, I'm planning to adopt it for my company for industrial automation.
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I would like to know a list of the most common application/websites/solutions where Erlang is used, successfully or not.
Explaining why it is used into a specific solution instead of others programming languages would be very much appreciated, too.
Listing BAD Erlang case studies (cases in which Erlang is misused) it would be interesting, as well.
From Programming Erlang:
(source: google.com)
Many companies are using Erlang in their production systems:
• Amazon uses Erlang to implement SimpleDB, providing database services as a part
of the Amazon Elastic Compute Cloud (EC2).
• Yahoo! uses it in its social bookmarking service, Delicious, which has more than
5 million users and 150 million bookmarked URLs.
• Facebook uses Erlang to power the backend of its chat service, handling more than
100 million active users.
• WhatsApp uses Erlang to run messaging servers, achieving up to 2 million connected users per server.
• T-Mobile uses Erlang in its SMS and authentication systems.
• Motorola is using Erlang in call processing products in the public-safety industry.
• Ericsson uses Erlang in its support nodes, used in GPRS and 3G mobile networks
worldwide.
The most popular open source Erlang applications include the following:
• The 3D subdivision modeler Wings 3D, used to model and texture polygon
meshes.
• The Ejabberd system, which provides an Extensible Messaging and Presence Protocol
(XMPP) based instant messaging (IM) application server.
• The CouchDB “schema-less” document-oriented database, providing scalability
across multicore and multiserver clusters.
• The MochiWeb library that provides support for building lightweight HTTP servers.
It is used to power services such as MochiBot and MochiAds, which serve
dynamically generated content to millions of viewers daily.
• RabbitMQ, an AMQP messaging protocol implementation. AMQP is an emerging
standard for high-performance enterprise messaging.
ejabberd is one of the most well know erlang application and the one I learnt erlang with.
I think it's the one of most interesting project for learning erlang because it is really building on erlang's strength. (However some will argue that it's not OTP, but don't worry there's still a trove of great code inside...)
Why ?
An XMPP server (like ejabberd) can be seen as a high level router, routing messages between end users. Of course there are other features, but this is the most important aspect of an instant messaging server. It has to route many messages simultaneously, and handle many a lot of TCP/IP connections.
So we have 2 features:
handle many connections
route messages given some aspects of the message
These are examples where erlang shines.
handle many connections
It is very easy to build scalable non-blocking TCP/IP servers with erlang. In fact, it was designed to solve this problem.
And given it can spawn hundreds of thousand of processes (and not threads, it's a share-nothing approach, which is simpler to design), ejabberd is designed as a set of erlang processes (which can be distributed over several servers) :
client connection process
router process
chatroom process
server to server processes
All of them exchanging messages.
route messages given some aspects of the message
Another very lovable feature of erlang is pattern matching.
It is used throughout the language.
For instance, in the following :
access(moderator, _Config)-> rw;
access(participant, _Config)-> rw;
access(visitor, #config{type="public"})-> r;
access(visitor, #config{type="public_rw"})-> rw;
access(_User,_Config)-> none.
That's 5 different versions of the access function.
Erlang will select the most appropriate version given the arguments received. (Config is a structure of type #config which has a type attribute).
That means it is very easy and much clearer than chaining if/else or switch/case to make business rules.
To wrap up
Writing scalable servers, that's the whole point of erlang. Everything is designed it making this easy. On the two previous features, I'd add :
hot code upgrade
mnesia, distributed relational database (included in the base distribution)
mochiweb, on which most http erlang servers are built on
binary support (decoding and encoding binary protocol easy as ever)
a great community with great open source projects (ejabberd, couchdb but also webmachine, riak and a slew of library very easy to embed)
Fewer LOCs
There is also this article from Richard Jones. He rewrote an application from C++ to erlang: 75% fewer lines in erlang.
The list of most common applications for Erlang as been covered (CouchDb, ejabberd, RabbitMQ etc) but I would like to contribute the following.
The reason why it is used in these applications comes from the core strength of Erlang: managing application availability.
Erlang was built from ground up for the telco environment requiring that systems meet at least 5x9's availability (99.999% yearly up-time). This figure doesn't leave much room for downtime during a year! For this reason primarily, Erlang comes loaded with the following features (non-exhaustive):
Horizontal scalability (ability to distribute jobs across machine boundaries easily through seamless intra & inter machine communications). The built-in database (Mnesia) is also distributed by nature.
Vertical scalability (ability to distribute jobs across processing resources on the same machine): SMP is handled natively.
Code Hot-Swapping: the ability to update/upgrade code live during operations
Asynchronous: the real world is async so Erlang was built to account for this basic nature. One feature that contributes to this requirement: Erlang's "free" processes (>32000 can run concurrently).
Supervision: many different strategies for process supervision with restart strategies, thresholds etc. Helps recover from corner-cases/overloading more easily whilst still maintaining traces of the problems for later trouble-shooting, post-mortem analysis etc.
Resource Management: scheduling strategies, resource monitoring etc. Note that the default process scheduler operates with O(1) scaling.
Live debugging: the ability to "log" into live nodes at will helps trouble-shooting activities. Debugging can be undertaken live with full access to any process' running state. Also the built-in error reporting tools are very useful (but sometimes somewhat awkward to use).
Of course I could talk about its functional roots but this aspect is somewhat orthogonal to the main goal (high availability). The main component of the functional nature which contributes generously to the target goal is, IMO: "share nothing". This characteristic helps contain "side effects" and reduce the need for costly synchronization mechanisms.
I guess all these characteristics help extending a case for using Erlang in business critical applications.
One thing Erlang isn't really good at: processing big blocks of data.
We built a betting exchange (aka prediction market) using Erlang. We chose Erlang over some of the more traditional financial languages (C++, Java etc) because of the built-in concurrency. Markets function very similarly to telephony exchanges. Our CTO gave a talk on our use of Erlang at CTO talk.
We also use CouchDB and RabbitMQ as part of our stack.
Erlang comes from Ericsson, and is used within some of their telecoms systems.
Outside telecoms, CouchDb (a document-oriented database) is possibly the best known Erlang application so far.
Why Erlang ? From the overview (worth reading in full):
The document, view, security and
replication models, the special
purpose query language, the efficient
and robust disk layout and the
concurrent and reliable nature of the
Erlang platform are all carefully
integrated for a reliable and
efficient system.
I came across this is in the process of writing up a report: Erlang in Acoustic Ray Tracing.
It's an experience report on a research group's attempt to use Erlang for Acoustic Ray Tracing. They found that while it was easier to write the program, less buggy, etc. It scaled worse, and performed 10x slower than a comparable C program. So one spot where it may not be well suited is CPU intensive scenarios.
Do note though, that the people wrote the paper were in the stages of first learning Erlang, and may not have known the proper development procedures for CPU intensive Erlang.
Apparently, Yahoo used Erlang to make something it calls Harvester. Article about it here: http://www.ddj.com/architect/220600332
What is erlang good for?
http://beebole.com/en/blog/erlang/why-erlang/
http://www.aquabu.com/2008/2/15/erlang-pragmatic-studio-day-3-notes
http://www.reddit.com/r/programming/comments/9q0lr/erlang_and_highfrequency_trading/
(jerf's answer)
It's important to realize that Erlang's 4 parts: the language itself, the VMs(BEAM, hipe) standard libs (plus modules on github, CEAN, etc.) and development environment are being steadily updated / expanded/improved. For example, i remember reading that the floating point performance improved when Wings3d's author realized it needed to improve (I can't find a source for this). And this guy just wrote about it:
http://marian-dan.com/wordpress/?p=324
A couple years ago, Tim Bray's Wide Finder publicity and all the folks starting to do web app frameworks and HTTP servers lead (at least in part) to improved regex and binaries handling. And there's all the work integrating HiPE and SMP, the dialyzer project, multiple unit testing and build libs springing up, ..
So its sweet spot is expanding, The difficult thing is that the official docs can't keep up very well, and the mailing list and erlang blogosphere volume are growing quickly
We are using Erlang to provide the back-end muscle power for our really real-time browser-based multi-player game Pixza. We don't use Flash or any other third-party plugins, though the game is real-time multi-player. We use pure JS and COMET techniques instead. And Erlang supports the "really realtimeliness" of Pixza.
I'm working for wooga, a social game company and we use Erlang for some of our game backends (basically http apis for millions of daily users) and auxiliary services like ios push notification provider, payment etc.
I think it really shines in network related tasks and it makes it kind of straight forward to structure and implement simple and complex network services alike in it. Distribution, fault tolerance and performance are easy to achieve because Erlang already has some of the key ingredients built in and they are being used for a long time in critical production infrastructure. So its not like "the new hip technology thing 0.0.2 alpha".
I know that other game companies use Erlang as well. You should be able to find presentations on slideshare about that.
Erlang draws its strength from being a functional language with no shared memory. Hence IMO, Erlang won't be suitable for applications that require in place memory manipulations. Image editing for example.
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I was recently approached by a network-engineer, co-worker who would like to offload his minor network admin duties to a junior-level helpdesk tech. The specific location in need of management acts as an ISP for tenants on its single-site property, so there's a lot of small adjustments being made on a daily basis.
I am thinking it would be helpful to write him a winform app to manage the 32 Cisco devices, on-site. I'd like to initially provide functionality which could modify access control lists, port VLAN assignments, and bandwidth limitations per VLAN... adding more to the list as its deemed valuable.
My initial thought was to emulate a telnet session with the network device; utilizing my network-engineer's familiarity with the command-line / IOS interaction. Minimal time would be required to learn Cisco IOS conventions, myself.
Though while searching for solutions, it appears that most people favor SNMP. That, or, their specific circumstances pushed them in the direction of SNMP.
I wanted to know if I've overlooked an obvious benefit of SNMP. Should I be using SNMP? Why or why not?
SNMP is great for getting information out of a Cisco device, but is not very useful controlling the device. (although technically, you can push a new config to a Cisco IOS device using a combination of SNMP and TFTP. But sending a whole new config is a pretty blunt instrument for controlling your router or switch).
One of the other commenters mentioned the Cisco IOS XR XML API. It's important to note that the IOS XR XML API is only available on devices that run IOS XR. IOS XR is only used on a few of Cisco's high end carrier class devices, so for 99% of all Cisco routers and switches the IOS XR XML API is not an option.
Other possibilities are SSH or HTTP (many Cisco routers, switches, AP, etc. have an optional web interface). But I'd recommend against either of those. To my knowledge, the web interface isn't very consistent across devices, and a rather surprising number of Cisco devices don't support SSH, or at least don't support it in the base license.
Telnet is really the only way to go, unless you're only targeting a small range of device models. To give you something to compare against, Cisco's own CiscoWorks network management software uses Telnet to connect to managed devices.
I wouldn't use SNMP, instead look at a little language called 'expect'. it makes for a very nice expect/response processor for these routers.
I have done a reasonable amount of real world SNMP programming with Cisco switches and find Python on top of Net-SNMP to be quite reasonable. Here is an example, via Google books, of uploading a new Cisco configuration via Net-SNMP and Python: Cisco Switch Upload via Net-SNMP and Python. I should disclose I was the co-author of the book referenced in the link.
Everyone's milage may vary, but I personally do not like using expect, and prefer to use SNMP because it was actually designed to be a "Simple Network Management Protocol". In a pinch, expect is ok, but it would not be my first choice. One of the reasons some companies use expect is that a developer just gets used to using expect. I wouldn't necessarily chock up bypassing SNMP just because there is an example of someone automating telnet or ssh. Try it out for self first.
There can be some truly horrible things that happen with expect, that may not be obvious as well. Because expect waits for input, under the right conditions there be very subtle problems that are difficult to debug. This doesn't mean a very experienced developer can't develop reliable code with expect, but it something to be aware of as well.
One of the other things you may want to look at is an example of using the multiprocessing module to write non-blocking SNMP code. Because this is my first post to stackoverflow I cannot post more then one link, but if you google for it you can find it, or another one on using IPython and Net-SNMP.
One thing to keep in mind when writing SNMP code is that it involves reading a lot of documentation and doing trial and error. In the case of Cisco, the documentation is quite good though.
SNMP isn't bad but it may not be able to do everything you need it to do. Depending on the library you use and how it hides the details of interacting with SNMP you may have a hard time finding the correct parts of the MIB to change and even knowing what or how to change them to do what you want.
One reason not to use SNMP is that you can do all the configuration you need using the IOS XR XML API. It could be a lot easier to bundle up the commands you want to send to the devices using that than to interact with SNMP.
I've found SNMP to be a pain for management. If you just need to grab a little data it's great; if you need to change things or use if heavily it can be very time consuming. In my case I'm comfortable with the CLI so a Telnet approach works well. I've written some Python scripts to perform administrative tasks on various pieces of network gear using Telnetlib
SNMP has quite a significant CPU hit on the devices in question compared to telnet; I'd recommend telnet wherever possible. (As stated in a previous answer, the IOS XR XML API would be nice, but as far as I know IOS XR is only deployed on high-end carrier grade routers).
In terms of existing configuration management systems, two commercial players are HP Opsware, and EMC Voyence. Both will probably do what you need. I'm not aware of many open source solutions that actually support deploying changes. (RANCID, for example, only does configuration monitoring, not pre-staging and deploying config changes).
If you are going to roll your own solution, one thing I would recommend is sitting down with your network admin and coming up with a best-practice deployment model for the service he's providing (e.g. standardised ACL, QoS queue, and VLAN names; similar entries in ACLs that have the same function for different customers, etc.). Ensure that all the existing deployed config complies with this BP before you start your design, it will make the problem much more manageable. Best of luck.
Sidenote: before you reinvent the wheel writing another service provisioning system/network management system, try looking for existing ones. I know quite a lot of commercial solutions of various degrees of flexibility/functionality, but I am sure there are quite a lot opensource ones.
Cisco has included menu options for helpdesk applications. Basically you telnet to the box and it presents a nice clean menu (press 1, 2, 3). For more info check this link:
http://www.cisco.com/en/US/docs/ios/12_2/configfun/command/reference/frf001.html#wp1050026
Another vote for expect.
Also, you don't want to allow configuration of your firewalls via either telnet or SNMP - ssh is the only way to go. The reason is that ssh encrypts its payload, and will not expose the privileged management credentials to potential interception.
If for some reason you cannot use ssh directly, consider connecting up an ssh-enabled serial console server to the firewall's console port and configuring it that way.