I've read the DMR description here (https://docs.solace.com/Features/Dynamic-Msg-Routing.htm). I'm finding a bit of trouble finding clear pros/cons between the use of internal links and external links. For my use case I have multiple remote appliances, so when I first heard of DMR I thought I would cluster some of those appliances up with internal links and then connect the clusters with external links. Playing around with it in my dev environment, and further reading reveals that I can't mix and match link types. Is the best practice in this case just creating one cluster and adding all of the routers to it, or creating multiple single node clusters and connecting them with external links?
Mixing internal links and external links will be supported in a future release, which would resolve the main issue I was having.
Related
Exam Question: You're using an external API, where the URL changes frequently. Which architecture is suited the best to solve this problem, without ever-changing the code for the program again?
I recently took an exam and there was this task to which i still cannot figure out the appropriate answer.The architectures mentioned in the lecture were P2P, C/S and SOA.
If anyone has a clue... Thanks!
I think the answer is p2p. In a Peer-to-peer network, computers advertise their services capabilities on the network. A changing URL would not be a problem, as the new URL is published to the network automatically and picked up by the consumers of the API.
In SOA and Client/Server the consumers of the API have no means to know about a change in the API URL.
I was browsing the wikipedia page on TIPC (http://en.wikipedia.org/wiki/TIPC) and noticed that the addressing scheme used is similar to Distributed Erlang's pid addresses, when you display it on a different node. Just wondering, since both efforts were developed at Ericsson. There is also some form of periodic ping (heartbeat) mechanism to tell whether the other process is up or not, similar to TIPC.
There is no direct relation, -at least no such relation was ever brought to my attention by the Erlang developers.
But knowing that they were once sitting at an adjacent floor to me in the same building, and there was some information sharing between us, I would be surprised if this is purely coincidental ;) Just for the record, the TIPC addressing scheme is several years older than Distributed Erlang.
I am planning to create a library related desktop application using Delphi 5, for which there would be a single database kept at one place and this application would be installed at different places more over in different cities.
Here, my doubt is Using Delphi 5, is it possible for all the instances of this application which are installed at different cities could access one centralized database? If yes then how?
If anybody is having any other ideas kindly feel free to share it. Because I have familiar to only desktop application development, that is the reason I am asking how these different instances of an application could access only one centralized database ?
So, all the screens and coding would be done using Delphi 5, moreover it would be a desktop application only the difference would be database access would be from different places.
That depends upon back-end database technology. By "desktop application development" u probably mean ISAM databases like Paradox, DBF-family, etc.
If so, then you should quickly learn about SQL, its concepts, ACID principles, etc.
I believe there is a lot of good books in English about SQL in general and SQL with Delphi link in particular. For staring u may try something like http://www.firebirdsql.org/en/books/, but basically you would have to cover three areas:
SQL in general, principles, patterns, etc
Details about Delphi wrt SQL designs.
Details about chosen database server, including components to connect it to Delphi, bugs, gotchas, etc
I think you'd hardly find all that in one book and would have to get two or three.
Then you would have make a network connection between clients and server.
That splits to two questions.
How to find server
How to connect to it
VPN are reliable solution, you may try Windows built-in methods, or simplier methods like TeamViewer, Comodo, Hamachi, etc
But that can make you whole server computer exposed to your clients.
You'd better find not whole-featured network, but a tunnel that would connect clients for database server and nothing else. In russian comunity classic solution to Firebird/Interbase family is http://sf.net/projects/zebedee for Windows. For Linux SSH is usually used.
You probably can find a lot of FAQ in English if you google for "tunneling" and you database server of Choice.
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 Program my local schools program launcher which allows students to get on the internet with an randomly generated key provided by a teacher. This is done by changing the proxy in Internet explorer to the one needed for the internet and the wb filter.
With the schools website and learning resources gradually moving to offsite hosting the internet key is needed for the students to access them. What the school would like is a way to enable these websites without unblocking the rest of the internet unless the internet key is given to the student.
The two ways ive come up with doing this by googleing is to block all websites in IE content adviser exept those that are allowed wthout the key. Or to create anouther proxy in delphi which the program can make ie point to and will only allow certain websites through to the real proxy.
I am reasonble fluent in simple delphi functions with an a level in computing but dont have a clue where to start with this and would appreciate any help.
Don't go through the DIY path - use a proxy with blacklist/whitelist functionalities, you can also set up a "transparent proxy" through which all internet traffic is routed and doesn't require to setup the proxy in browsers. You can also use proxy authentication to setup who can access what.
In Delphi you will end up to write a proxy with the same functionalities. If you don't have a very good rason to write your own proxy, it's far better to go through an already existing solutions, which also is already tested by a lot of users. There are commercial and opensource/free ones.
If you really like to write a proxy in Delphi:
A good knowledge of how TCP, HTTP(S), and a proxy works is required.
The application needs to be a service, and should be robust or accessing the Internet may be become impossible.
The application will have to serve concurrent requests, thereby it needs to be multithreaded (Indy offers a basic HTTP proxy component - how well it scales I do not know, and it implements basic features only).
If you need authentication, knowledge of authentication methods and if integrated authentication is needed, how Windows auhtentication works.
It should be tested with all the browser type used.
Although a very interesting app to write from scratch if you liked to learn about that all, if you have a "business need" it's better to use an already existing one.
+1 and the proxy may cache some of the Internet resources, so the whole Internet experience will be smoother with such a tool.
I'll recommend using a linux box (some old PC can be revamped into this) with Squid, just to separate your students network to the Internet. There is a lot of info on the Internet about that, and also dedicated linux distributions: a lot of schools around the world had the same problem!
OpenDNS is the best place to start. Put that up, set all PCs to use it, and that'll take care of most of your problems.